A microporous metal–organic framework [Cu2L(H2O)2]·(DMF)0.5·(H2O)7, (ZJU-195, H4TTCA-NH2 = 5-amino-3,3,5,5-tetracarboxylic acid, DMF = N,N-dimethylformamide) has been designed, synthesized, structurally characterized, and examined for its gas storage and separation. The activated ZJU-195a has achieved high C2H2 storages of 275.6 cm3·g–1 at 273 K and 214.2 cm3·g–1 at 298 K under 1.0 bar. Furthermore, ZJU-195a selectively adsorbs C2H2 over CO2 and CH4, exhibiting moderately high C2H2/CH4 and C2H2/CO2 separations at ambient conditions with an ideal adsorbed solution theory selectivity of 43.4–64.6 and 4.7–12.4, respectively.

•A thermostable Eu/Tb-codoped MOF exhibiting strong luminescent at elevated temperature is reported.•The high-temperature operating range of Eu0.37Tb0.63-BTC-a is 313–473 K.•The mechanism of Eu0.37Tb0.63-BTC-a used as thermometers are also discussed.Temperature measurements and thermal mapping using luminescent MOF operating in the high-temperature range are of great interest in the micro-electronic diagnosis. In this paper, we report a thermostable Eu/Tb-mixed MOF Eu0.37Tb0.63-BTC-a exhibiting strong luminescence at elevated temperature, which can serve as a ratiometric luminescent thermometer for high-temperature range. The high-temperature operating range (313–473 K), high relative sensitivity and accurate temperature resolution, make such a Eu/Tb-mixed MOF useful for micro-electronic diagnosis.A thermostable Eu/Tb-mixed MOF Eu0.37Tb0.63-BTC-a was developed as a ratiometric luminescent thermometers in the high-temperature range of 313–473 K.

•A water-stable metal-organic framework (MOF) EuNDC was synthesized.•The highly selective detection of picric acid with a detection limit of 37.6 ppb was realized.•The detection mechanism were also presented and discussed.A water-stable metal-organic framework (MOF) EuNDC has been synthesized for selective detection of the well-known contaminant and toxicant picric acid (PA) in aqueous solution. Due to the photo-induced electron transfer and self-absorption mechanism, EuNDC displayed rapid, selective and sensitive detection of PA with a detection limit of 37.6 ppb. Recyclability experiments revealed that EuNDC retains its initial luminescent intensity and same quenching efficiency in each cycle, suggesting high photostability and reusability for long-term sensing applications. The excellent detection performance of EuNDC makes it a promising PA sensing material for practical applications.A water-stable europium-based metal-organic framework has been reported for highly selective sensing of picric acid (PA) with a detection limit of 37.6 ppb in aqueous solution.

We report a cerium metal–organic framework (ZJU-136-Ce) for the turn-on fluorescence sensing of AA. The fluorescence enhancement is attributed to the specific redox reaction between AA and Ce4+. The detection limit of AA reaches 7 nM, showing its potential for AA detection in the environmental industry and clinical medicine.

The precise and real-time monitoring of localized pH changes is of great importance in many engineering and environmental fields, especially for monitoring small pH changes in biological environments and living cells. Metal–organic frameworks (MOFs) with their nanoscale processability show very promising applications in bioimaging and biomonitoring, but the fabrication of nanoscale MOFs is still a challenge. In this study, we synthesized a nanoscale mixed-lanthanide metal–organic framework by a microemulsion method. The morphology and size of the NMOF can be simply adjusted by the addition of different amounts of the CTAB surfactant. This NMOF exhibits significant pH-dependent luminescence emission, which can act as a self-referenced pH sensor based on two emissions of Tb3+ at 545 nm and Eu3+ at 618 nm in the pH range from 3.00 to 7.00. The MTT assay and optical microscopy assay demonstrate the low cytotoxicity and good biocompatibility of the nanosensor.

A tetracarboxylic acid ligand containing a highly polarized benzothiadiazole moiety was designed and used to construct the luminescent porous MOF ZJU-21, which can efficiently absorb the luminescent dye 4-[p-(dimethylamino)styryl]-1-methylpyridinium (DMASM) into the pores as well as sensitize it, yielding a dual-emitting MOF⊃dye composite ZJU-21⊃DMASM. The emission color of the resulting composite can be modulated by controlling the amount of dyes, and the intensity ratio of the two emissions can be used as a ratiometric thermometric parameter for temperature measurement. ZJU-21⊃DMASM also exhibits excellent temperature-dependent photoluminescence properties in the physiological temperature range, which, as well as the temperature and sensitivity ranges, can be tuned by controlling the concentration of DMASM in the pores of the host framework. Moreover, the proposed scheme can be readily applied to other luminescent porous MOFs and organic dyes, thereby providing a new perspective for the design of MOF⊃dye ratiometric temperature sensors.

A MOF thermometer, Dycpia, utilizing thermally coupled energy levels (TCELs) has been realized. Based on two emissions originating from two TCELs, Dycpia enables self-referenced temperature sensing in the range from 298 to 473 K with a high resolution of 0.05 K.

•A triazole-based UiO-66-PSM is synthesized by the CuAAC click reaction.•The triazole unit can act as the metal binding sites to coordinate with Hg2+.•It is capable of detecting Hg2+ in environmental water samples.A novel metal-organic framework (MOF) fluorescent probe UiO-66-PSM is obtained by the copper-catalyzed azide-alkyne click (CuAAC) reaction of UiO-66-N3 with phenylacetylene. The click-generated triazole unit can act as the metal binding site to coordinate with Hg2+, which exhibits the most pronounced fluorescence response (rapid response, excellent selectivity, and high sensitivity) over other metal ions. Moreover, it is capable of detecting Hg2+ in environmental water samples without any structural disintegration of the framework, indicating its high potential in practical applications.A novel metal-organic framework (MOF) UiO-66-PSM is obtained by the copper-catalyzed azide-alkyne click (CuAAC) reaction of UiO-66-N3 with phenylacetylene. This MOF exhibits the high potential in detecting Hg2+ in environmental water samples.Download high-res image (152KB)Download full-size image

•We designed a new metal-organic framework UiO-66-CH=CH2 for biological H2S sensing.•The responsive time was 10 s and the detection limit was 6.46 μM.•This probe has anti-interference especially from cysteine and glutathione.•This biological H2S probe features low cytotoxicity, water-stability and nanoscale.Hydrogen sulfide (H2S) has been commonly viewed as a gas signaling molecule in various physiological and pathological processes. However, the highly efficient H2S detection still remains challenging. Herein, we designed a new robust nano metal-organic framework (MOF) UiO-66-CH=CH2 as a fluorescent probe for rapid, sensitive and selective detection of biological H2S. UiO-66-CH=CH2 was prepared by heating ZrCl4 and 2-vinylterephthalic acid via a simple method. UiO-66-CH=CH2 displayed fluorescence quenching to H2S and kept excellent selectivity in the presence of biological relevant analytes especially the cysteine and glutathione. This MOF-based probe also exhibited fast response (10 s) and high sensitivity with a detection limit of 6.46 μM which was within the concentration range of biological H2S in living system. Moreover, this constructed MOF featured water-stability, nanoscale (20–30 nm) and low toxicity, which made it a promising candidate for biological H2S sensing.A nanoscale Zr-based fluorescent metal-organic framework was synthesized for selective and sensitive biological detection of hydrogen sulfide.Download high-res image (179KB)Download full-size image

•ZJU-197 has been structurally characterized as a novel MOF.•ZJU-197a exhibits excellent gas separation.•The gas separation is mainly attributed to the relatively narrow channels and open metal sites.Efficient separation of the small gas molecules especially the hydrocarbons is essential to social economy. The microporous metal-organic frameworks (MOFs) are taking precedence in this respect by virtue of their irreplaceable advantages. Herein, the new organic linker 5-(5-carboxypyridin-3-yl)isophthalic acid simplified as H3L-N has been excavated to construct successfully the novel Zn-based heterocycle metal-organic framework ZnL·(DMF)1.5·(H2O)6.0 (ZJU-197, ZJU = Zhejiang University, DMF = N,N-dimethylformamide). ZJU-197 has been structurally characterized and explored in details for gas separation. It is commendable that the activated ZJU-197a has exhibited excellent C2H2/C2H4, CO2/CH4 and CO2/N2 separations simultaneously with IAST selectivity of 137.8, 53.0 and 514.1 respectively at ambient conditions.Download high-res image (168KB)Download full-size image

•A novel MOF film was fabricated on porous α-Al2O3 ceramic plate.•The europium functionalized MIL-1244@Eu3+ exhibited excellent ammonia sensitivity.•MIL-1244@Eu3+ sensor showed good long-term stability and repeatability.•The mechanism of the ammonia sensing property was explored by FT-IR spectrum.A novel metal-organic framework film MIL-124 film was prepared on porous α-Al2O3 ceramic plate by in situ synthesizing. After introducing Eu3+ ions to the free -COOH sites of the MIL-124 ligand channels, a luminescent MOF film MIL-124@Eu3+ was obtained. Based on the chemical reaction between NH3 and the -COOH, the formation of -COONH4 which was demonstrated by FT-IR spectrum, affected the energy transfer between Eu3+ ions and ligand, quenching the characteristic emission of MIL-124@Eu3+ film. The limit of detection to ammonia was calculated as 26.2 ppm in ambient air. The XRD results demonstrated the long-term stability of this ammonia sensor. The excellent performance and economical synthesizing strategy of the MIL-124@Eu3+ film exhibited potential application of this sensor for detecting ammonia gas.Download high-res image (243KB)Download full-size image

•A porous Zn-based metal-organic framework (MOF) Zn-TBDA was prepared exhibiting negligible cytotoxicity.•Zn-TBDA showed desirable drug Methotrexate loading.•Zn-TBDA showed sensitive pH and temperature dual-responsive controlled release of Methotrexate.A porous metal-organic framework Zn-TBDA (TBDA = 4′-(1H-tetrazol-5-yl) -[1,1′-biphenyl]-3,5-dicarboxylic acid) with one-dimensional channels has been synthesized from zinc ions and bifunctional ligands. The negligible cytotoxicity of Zn-TBDA is confirmed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay and microscopy observation. The anticancer drug methotrexate (MTX) is loaded into Zn-TBDA successfully via in-situ encapsulation and the loading capability reaches about 12.59 wt% in resulting composite MTX-encapsulated Zn-TBDA. Under different physiological microenvironments, MTX-encapsulated Zn-TBDA exhibits sensitive pH and temperature dual-responsive release manners, revealing its practical value as a smart drug carrier with controlled release in certain site and improved therapeutic efficacy without any additional external fields.A porous metal-organic framework (MOF) Zn-TBDA has been synthesized. The negligible cytotoxicity, desirable drug loading capability and controlled release manners of Zn-TBDA shows it can be used as a drug vehicle. Especially, the pH and temperature dual-responsive drug release of material confirms the potential applications of Zn-TBDA as a smart drug carrier.Download high-res image (208KB)Download full-size image

Due to the periodically physical/chemical environment and high-efficient confinement effect of the metal-organic framework (MOF) only possessing 1D channels, the authors realize periodically and highly aligned dye molecule integration within the MOF hybrid material ZJU-68⊃DMASM. Such molecule integration can provide an opportunity to directly determine 4-[p-(dimethylamino)styryl]-1-methylpyridinium (DMASM) molecules in the MOF channels by electron density mapping using X-ray diffraction data. Furthermore, combining the anisotropic emission property of such molecule integration and the perfect crystal morphology of ZJU-68 serving as the natural resonant cavity, the authors obtain a single-mode linearly polarized laser excited by light ranging from visible to near-infrared.

The efficient separation of C2H2 versus C2H4 and CH4 to obtain high-purity C2H2 and C2H4 is of significance for making full, economic use of these raw chemicals. Herein, an amino-coordination microporous metal–organic framework ZJU-198, ZnL·DMF (ZJU = Zhejiang University, L = (2E,2E′)-3,3′-(5-amino-1,3-phenylene)diacrylic acid, DMF = N,N′-dimethylformamide), has been demonstrated as a valuable adsorbent for C2H2/C2H4 and C2H2/CH4 separations. The activated ZJU-198a exhibits moderate C2H2 uptakes (99.4 cm3 cm−3 for 273 K and 98.4 cm3 cm−3 for 298 K under 1.0 bar) and moderately high C2H2/C2H4 selectivity (5.8 to 7.7 at 273 K and 4.8 to 7.2 at 298 K). Specifically, the C2H2/CH4 selectivity of ZJU-198a reaches up to 497.9 and 391.1 at 273 K and 298 K, respectively. To the best of our knowledge, the C2H2/CH4 selectivity coefficients of ZJU-198a at both 298 K and 273 K are the highest values among the reported metal–organic frameworks, meaning that there is bright potential for ZJU-198a in hydrocarbon storage and separation.

A methoxy-decorated novel metal–organic framework (MOF), Cu2(DTPD) (ZJU-12, H4DTPD = 5,5′-(2,6-dimethoxynaphthalene-1,5-diyl)diisophthalic acid) with optimized pore space and open metal sites, was solvothermally synthesized and structurally characterized. The activated ZJU-12a displays a moderately high BET (Brunauer–Emmett–Teller) surface area of 2316 m2 g−1. Due to the pore size of the crystal being consistent with the molecular size and kinetic diameters of C2H2 and CO2, ZJU-12a exhibits a high C2H2 storage capacity of 244 cm3 g−1 and CO2 capture capacity of 134 cm3 g−1 at room temperature.

A novel fluorescent probe was synthesized and explored to detect cadmium ions (Cd2+) based on an imine functionalized metal–organic framework (MOF). The nanoscale MOF probe (∼100 nm) displayed a turn-on fluorescence in aqueous environments with the addition of Cd2+ which could be ascribed to the interaction between the CN group and specific metal ions, presenting a low-toxicity, highly selective and sensitive detection method for Cd2+ with a detection limit of 0.336 μM (37.8 ppb) and a broad linear range of 0–500 μM, which is promising for application in intracellular sensing and imaging of Cd2+. The probing mechanism was studied and discussed in detail.

Discoveries of novel functional materials have played very important roles to the development of science and technologies and thus to benefit our daily life. Among the diverse materials, metal–organic framework (MOF) materials are rapidly emerging as a unique type of porous and organic/inorganic hybrid materials which can be simply self-assembled from their corresponding inorganic metal ions/clusters with organic linkers, and can be straightforwardly characterized by various analytical methods. In terms of porosity, they are superior to other well-known porous materials such as zeolites and carbon materials; exhibiting extremely high porosity with surface area up to 7000 m2/g, tunable pore sizes, and metrics through the interplay of both organic and inorganic components with the pore sizes ranging from 3 to 100 Å, and lowest framework density down to 0.13 g/cm3. Such unique features have enabled metal–organic frameworks to exhibit great potentials for a broad range of applications in gas storage, gas separations, enantioselective separations, heterogeneous catalysis, chemical sensing and drug delivery. On the other hand, metal–organic frameworks can be also considered as organic/inorganic self-assembled hybrid materials, we can take advantages of the physical and chemical properties of both organic and inorganic components to develop their functional optical, photonic, and magnetic materials. Furthermore, the pores within MOFs can also be utilized to encapsulate a large number of different species of diverse functions, so a variety of functional MOF/composite materials can be readily synthesized.In this Account, we describe our recent research progress on pore and function engineering to develop functional MOF materials. We have been able to tune and optimize pore spaces, immobilize specific functional groups, and introduce chiral pore environments to target MOF materials for methane storage, light hydrocarbon separations, enantioselective recognitions, carbon dioxide capture, and separations. The intrinsic optical and photonic properties of metal ions and organic ligands, and guest molecules and/or ions can be collaboratively assembled and/or encapsulated into their frameworks, so we have realized a series of novel MOF materials as ratiometric luminescent thermometers, O2 sensors, white-light-emitting materials, nonlinear optical materials, two-photon pumped lasing materials, and two-photon responsive materials for 3D patterning and data storage.Thanks to the interplay of the dual functionalities of metal–organic frameworks (the inherent porosity, and the intrinsic physical and chemical properties of inorganic and organic building blocks and encapsulated guest species), our research efforts have led to the development of functional MOF materials beyond our initial imaginations.

The first luminescent two-dimensional MOF nanosheets NTU-9-NS Ti2(HDOBDC)2(H2DOBDC) (H2DOBDC = 2,5-dihydroxyterephthalic acid) fabricated via top-down delamination have been realized for the highly sensitive sensing of Fe3+ with a fast response. The highly dispersive nature and highly accessible active sites on the surface of the 2D NTU-9-NS nanosheets enable them to have close contact with targeted metal ions, which leads to the highly sensitive sensing of Fe3+ ions, with a fast response time within seconds and the best detection limit performance of 0.45 μM among MOF materials. The fast response and highly sensitive Fe3+ sensing based on the NTU-9-NS nanosheets sensor material highlights the promise of the two-dimensional MOF nanosheet approach for luminescent sensing applications. This work contributes to the development of research on two-dimensional MOF nanosheets materials with targeted and specific recognition for the application of biological and environmental luminescent sensors.

A near-infrared luminescent metal–organic framework Nd0.866Yb0.134BTB was developed as a self-calibrated thermometer in the physiological range. Its features include high sensitivity and resolution, and good biocompatibility, making such a material useful for biomedical applications.

A novel metal–organic framework (MOF), [Cu2L(H2O)2]·7DMF·4H2O [ZJU-40; H4L = 5,5′-(pyrazine-2,5-diyl)diisophthalic acid], with Lewis basic nitrogen sites has been constructed and structurally characterized. Owing to the combined features of high porosity, moderate pore sizes, and immobilized Lewis basic nitrogen sites, the activated ZJU-40a exhibits the second-highest gravimetric C2H2 uptake of 216 cm3 g–1 (at 298 K and 1 bar) among all of the reported MOFs so far. This value is not only much higher than that of the isoreticular NOTT-101a (184 cm3 g–1), but also superior to those of two very promising MOFs, known as HKUST-1 (201 cm3 g–1) and Co-MOF-74 (197 cm3 g–1). Interestingly, the immobilized nitrogen sites in ZJU-40a have nearly no effect on the CO2 uptake, so ZJU-40a adsorbs a similar amount of CO2 (87 cm3 g–1) compared with NOTT-101a (84 cm3 g–1) at 298 K and 1 bar. As a result, ZJU-40a shows significantly enhanced adsorption selectivity for C2H2/CO2 separation (17–11.5) at ambient temperature compared to that of NOTT-101a (8–9), leading to a superior MOF material for highly selective C2H2/CO2 separation.

A nanoscale cationic porous drug carrier ZJU-101 (ZJU = Zhejiang University), synthesized by the solvothermal method to get the crystal size of ∼300 nm, was used to load diclofenac sodium, an anionic drug. This positively charged host materials showed a large loading capacity of diclofenac sodium (∼0.546 g/g) through ion exchange and penetration procedures. The drug delivery in the inflamed tissues (pH = 5.4) exhibited a more effective release in comparison with that in the normal tissues (pH = 7.4), demonstrating a physiological pH responsive drug release. This discriminating drug release process was controlled by anion exchange between anions in phosphate buttered saline (PBS) and coordinated/free diclofenac anions.

Metal–organic frameworks (MOFs), self-assembled from metal ions with organic ligands, are well known for their intriguing framework topology, permanent porosity, and tunable optical properties and have shown great promise for a good number of applications. Over the past few years, luminescent MOFs have attracted growing attention, especially for developing various luminescent sensors, by virtue of their excellent selectivity and high sensitivity. In this feature article, we highlight some of the recent significant progress in this active research field, and provide a comprehensive review on luminescent MOFs as sensory materials for diverse sensing applications including for metal ions, anions, small molecules and gases, nitroaromatics and explosives, temperature, as well as other aspects.

Two series of cationic dyes, named DM-n and DP-n, were encapsulated in three anionic isostructural MOFs with a 1D channel. Ordered arrangement of the dyes in the channel was investigated by using the microscope polarized absorption spectra of different dye and MOF composites. Furthermore, the tunable second order nonlinear optical properties of these MOF⊃dye materials were observed.

•A novel 3D NbO-type microporous metal-organic framework ZJU-10 was solvothermally synthesized and structurally characterized.•ZJU-10a exhibits high BET surface area of 2392 m2/g.•ZJU-10a shows a moderately high C2H2 gravimetric (volumetric) uptake capacity of 174 (132) cm3/g at 298 K and 1 bar.•ZJU-10a can separate acetylene from methane and carbon dioxide gas mixtures at room temperature.A novel 3D microporous metal-organic framework with NbO topology, [Cu2(L)(H2O)2]∙(DMF)6·(H2O)2 (ZJU-10, ZJU = Zhejiang University; H4L =2′-hydroxy-[1,1′:4′,1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid; DMF =N,N-dimethylformamide), has been synthesized and structurally characterized. With suitable pore sizes and open Cu2+ sites, ZJU-10a exhibits high BET surface area of 2392 m2/g, as well as moderately high C2H2 volumetric uptake capacity of 132 cm3/cm3. Meanwhile, ZJU-10a is a promising porous material for separation of acetylene from methane and carbon dioxide gas mixtures at room temperature.A new NbO-type microporous metal-organic framework ZJU-10 with suitable pore size and open Cu2+ sites was synthesized to realize the strong interaction with acetylene molecules, which can separate the acetylene from methane and carbon dioxane gas mixtures at room temperature.

•A ratiometric near infrared luminescent MOFs thermometer (Nd0.676Yb0.324BTC) was prepared via a simple solvothermal method.•The maximum relative sensitivity of Nd0.676Yb0.324BTC is determined to be 1.187% K−1 at 323 K.•Nd0.676Yb0.324BTC showed excellent repeatability in the physiological temperature range (288–323 K).A near infrared luminescent MOFs thermometer (Nd0.676Yb0.324BTC) was prepared via a simple solvothermal method using Ln3+ (Ln=Nd, Yb) ions and 1, 3, 5-benznenetricarboxylic acid (H3BTC), and characterized by PXRD, TGA, ICP, and photoluminescence (PL) spectrum. These results indicate that the Nd0.676Yb0.324BTC displays high relative sensitivity and excellent repeatability in the physiological temperature range (288–323 K), and the maximum relative sensitivity is determined to be 1.187% K−1 at 323 K. These NIR luminescent MOFs may have potential applications in physiological temperature sensing.A near infrared luminescent MOFs thermometer (Nd0.054Yb0.946BTC ) displays high relative sensitivity and excellent repeatability in the physiological temperature range (288–323 K).

•A new anionic MOF ZJU-71 was synthesized and structurally characterized.•ZJU-71 has one-dimensional channels along a axis and a scu type topology.•ZJU-71 can quickly and effectively remove the trace amounts of methylene blue.A novel 3D anionic microporous metal-organic framework, Cu2(H4DCPPA) (ZJU-71, H4DCPPA=[1,1′:2′,1′′-terphenyl]-4,4′,4′′,5′-tetracarboxylic acid, ZJU=Zhejiang University), has been synthesized and structurally characterized. ZJU-71 possesses one-dimensional channels along a axis and a scu type topology. The negative electricity of the framework makes ZJU-71 an candidate for effective elimination of cationic contaminants.A new three-dimensional anionic metal organic frameworks has been achieved and can effectively remove the trace amounts of methylene blue from aqueous solution and testified the anionic framework has strong interactions with the methylene blue.

A doubly interpenetrated metal–organic framework [Cu2L(DMF)(H2O)]·DMF·H2O (ZJU-199, ZJU = Zhejiang University; H3BTTA = benzene-1,3,5-triacrytic acid; DMF = N,N-dimethylformamide) has been successfully synthesized. The resulting ZJU-199 exhibits moderate C2H2 uptake of 128.0 cm3·g–1 and high selectivity for separation of C2H2/CH4 (27.3 to 33.5) and C2H2/CO2 (4.0 to 5.8) at room temperature.

The sensing of hydrogen sulfide (H2S) has become a long-time challenging task. In this work, we developed a general strategy for sensing of H2S utilizing postsynthetic modification of a nano metal–organic frameworks (MOF) UiO-66-(COOH)2 with Eu3+ and Cu2+ ions. The nano MOF Eu3+/Cu2+@UiO-66-(COOH)2 displays the characteristic Eu3+ sharp emissions and the broad ligand-centered (LC) emission simultaneously. Because H2S can strongly increase the fluorescence of Eu3+ and quench the broad LC emission through its superior affinity for Cu2+ ions, the MOF Eu3+/Cu2+@UiO-66-(COOH)2 exhibits highly sensitive turn-on sensing of H2S over other environmentally and biologically relevant species under physiological conditions. Furthermore, this approach for fluorescent turn-on sensing of H2S is expected to extend to other water-stable MOFs containing uncoordinated −COOH.Keywords: fluorescent probes; hydrogen sulfide; metal−organic frameworks; ratiometric sensing; turn-on;

Two-photon processing presents a facile means to tailor the properties of materials in three-dimensions. A two-photon responsive metal–organic framework (MOF) has been realized through the incorporation of a photoactive linker into a MOF via a multivariate strategy. The resulting MOF exhibits a significant one-photon and two-photon excited fluorescence change in response to UV light and infrared femtosecond laser, enabling spatial modulation of the fluorescence property of the MOF. It thus demonstrates the capacity of two-photon patterning and imaging inside the crystal, and the formation of three-dimensional two-photon excited fluorescent structure in a high resolution.

A cationic robust Zr-cluster-based metal–organic framework has been developed for the efficient removal of Cr2O72− from aqueous solutions.

Metal–organic frameworks (MOFs) hold great promise for developing various types of luminescent sensors due to their remarkable structural diversity and tunable luminescence properties. In the last few years, utilizing luminescent MOFs to explore temperature sensing has gained intense attention. In this feature article, after the general description of luminescence thermometry, we have summarized the recent progress made in luminescent MOF thermometers, with particular emphasis on the dual-emitting MOFs that effectively illustrate the self-referencing temperature measurement based on the intensity ratios of two separate transitions.

A near infrared pumped luminescent metal–organic framework thermometer Nd0.577Yb0.423BDC-F4, with near infrared fluorescence and excellent sensitivity in the physiological temperature range (293–313 K), has been first realized, and might be potentially applied for biomedical systems.

The mixed-metal–organic framework approach and a representative zirconium–metalloporphyrin framework (MOF-525) have been developed to create novel sulfur hosts and Li–S batteries. The different local environments at the centers of the porphyrin moieties in a series of MMOFs—MOF-525(2H), MOF-525(FeCl), and MOF-525(Cu)—have led to their different behaviors for the confinement of sulfur and thus Li–S batteries. The unique structure of MOF-525(Cu) has enabled each Cu2+ site to offer two Lewis acidic sites, featuring it as a very powerful MOF host for the inclusion of sulfur and polysulfides. The S@MOF-525(Cu) cathode has demonstrated the best performance among all reported sulfur/MOFs composite cathode materials, with a reversible capacity of about 700 mAh/g at 0.5 C after 200 cycles.Keywords: Lewis acidic sites; lithium−sulfur battery; metalloporphyrin ligand; metal−organic framework; sulfur confinement

An important result of research on mixed-lanthanide metal–organic frameworks (M′LnMOFs) is the realization of highly sensitive ratiometric luminescent thermometers. Here, we report the design and synthesis of the new M′LnMOF Tb0.80Eu0.20BPDA with high relative sensitivity in the physiological temperature regime (298–318 K). The emission intensity and luminescence lifetime were investigated and compared to those of existing materials. It was found that the temperature-dependent luminescence properties of Tb0.80Eu0.20BPDA are strongly associated with the distribution of the energy levels of the ligand. Such a property can be useful in the design of highly sensitive M′LnMOF thermometers.

A new organic hexacarboxylic acid, 5,5′,5″-(9H-carbazole-3,6,9-triyl)triisophthalic acid (H6CTIA), was developed to construct its first microporous metal–organic framework (MOF), Cu6(CTIA)2 (ZJU-70). With open metal sites and suitable pore sizes, this MOF exhibits high acetylene and methane storage capacities at room temperature.

•Pyrromethene dyes doped elastic films as active layers of organic VCSELs.•Mechanically tunable single mode laser emission from 590 to 690 nm.•High slope efficiencies with low laser threshold and wide tuning range.•Under somewhat tough pumping, laser output kept almost unchanged after 1 × 105 pulses.•Fast self-recovery on laser output depending on the dye molecular structure.In this work, various pyrromethene dyes were doped into elastic films of polydimethylsiloxane (PDMS) as active layers of organic VCSELs and the laser properties of such PDMS-based VCSELs were systematically investigated. Mechanically tunable laser emission with high slope efficiencies, low threshold and wide tuning range were obtained. By uploading various stress or changing distributed-Bragg reflector (DBR) mirrors, single mode laser emission could be tuned from ∼590 to 690 nm, indicating their potential applications as cost-effective coherent sources on bio-chips. Under the pump energy 10 times higher than the threshold, the laser emission of organic VCSELs remained at its initial level after 1.2 × 105 pulses and a fast self-recovery process on the laser output energy with the elapse of aging time was observed. The differences between the self-recovery rates of various pyrromethene dyes were also discussed.

A novel noninterpenetrated metal–organic framework [Cu2L(H2O)2]f·(DMA)18·(H2O)19 (ZJU-31, ZJU = ZheJiang University; H4L = 5′,5′′′′-(2,5-dimethoxy-1,4-phenylene)bis[1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic acid; DMA = N,N-dimethylacetamide) has been synthesized and structurally characterized from an expanded organic linker. Interestingly, although the new linker is larger than the developed one for the construction of ZJU-30 with a doubly interpenetrated structure, the incorporation of a 1,4-dimethoxyphenyl group into the new linker enforces the formation of noninterpenetrated ZJU-31. Accordingly, the activated ZJU-31a shows a much higher porosity with a BET surface area of 1115 m2/g than ZJU-30a of 228 m2/g. ZJU-31a exhibits highly selective separation of C2 hydrocarbons over C1 methane at room temperature.

SnO2 nanoparticles have been immobilized inside MIL-101(Cr) crystals achieving the novel SnO2@MIL-101(Cr) anode material with a multiple-core/shell structure. Under the protection of MIL-101(Cr) shell, the pulverization and aggregation of SnO2 during cycling have been diminished. Both good cyclability and rate capability with a reversible capacity of ∼510 mA h g−1 at 0.1C after 100 cycles have revealed.

•Novel porous Cr2O3@TiO2 yolk/shell structure constructed from MIL-101(Cr).•Multiple-core structure with small core size and moderate BET surface area.•Exhibiting improved lithium storage performance compared with bare Cr2O3 due to the yolk/shell structure.To make use of a metal–organic framework MIL-101(Cr3+) as template and core generator, we report synthesis of a novel nanoscale yolk/shell octahedron of Cr2O3@TiO2 and its high performance as the anode material for lithium ion battery. Nanoscale MIL-101(Cr3+) was coated with amorphous TiO2 shell and calcinated under Ar and then in air atmospheres to form nanoscale Cr2O3@TiO2. After heat treatment, the amorphous TiO2 coated MIL-101(Cr) was transformed into nanosized Cr2O3 crystals with crystalline TiO2 cover, forming multicore yolk/shell octahedrons, as demonstrated from their SEM and TEM morphologies. The resulting Cr2O3@TiO2 has moderate porosity with the BET surface area of 146 m2 g−1, and the diameter of its Cr2O3 cores is 10–40 nm. It has demonstrated a reversible capacity of 510 mA h g−1 after 500 cycles at 0.5 C charge/discharge rate, which is much better than the bare nano Cr2O3 without TiO2 shell, and is one of the best-performed Cr2O3 anode materials. The improved electrochemical performance of Cr2O3@TiO2 is attributed to its small particle size with moderate porosity for the infiltration of electrolyte and the fast diffusion of Li+ ions, its void space within yolk/shell structure to buffer volumetric variation of Cr2O3 and its TiO2 shell to restrain pulverized inner particles.

•Two microporous metal-organic frameworks have been synthesized and characterized.•The metal-organic frameworks exhibit high acetylene storage capacity.•The metal-organic frameworks exhibit high selectivities of C2H2/CH4 and C2H2/CO2.Two isostructural metal-organic frameworks (MOFs) Cu2TPTC-Me and Cu2TPTC-OMe have been synthesized and characterized. The as-synthesized MOFs show good thermal stability and hydrothermal stability. With open metal sites, suitable pore spaces and functional groups to confine acetylene molecules in frameworks, both MOFs exhibit high gravimetric acetylene storage capacities: Cu2TPTC-Me has a gravimetric capacity of 203 cm3 g−1 at 298 K and 1 bar, and Cu2TPTC-OMe has the highest gravimetric acetylene storage capacity ever reported with the capacity of 204 cm3 g−1 under the same conditions. Furthermore, Cu2TPTC-Me possesses both high separation selectivities of C2H2/CH4 and C2H2/CO2 with the Henry law's selectivity of 60 and 12.7 at room temperature, respectively.

A new NbO type metal–organic framework [Cu2(NPA)(H2O)2](DMF)5.5(H2O)0.5 (ZJU-9, H4NPA = 1,5-naphthalene-m-phthalic acid) with moderately high permanent porosity, open metal sites and appropriate pore sizes was designed and synthesized, exhibiting high storage capacities for both acetylene and methane at room temperature.

A novel amino-decorated NbO-type metal–organic framework [Cu2(C22H11NO8)(H2O)2]·(DMF)6·(H2O), (ZJU-8, ZJU = Zhejiang University; DMF = N,N-dimethylformamide) has been synthesized and structurally characterized. The activated ZJU-8a exhibits both a high C2H2 uptake capacity (195 cm3 g−1 at 1 bar) and a moderately high adsorption selectivity for CO2 over N2 (12.27) and CH4 (7.38) at room temperature.

Luminescent metal–organic framework films, CPM-5⊃Tb3+ and MIL-100(In)⊃Tb3+, have been constructed by postfunctionalization of two porous indium–organic frameworks with different structures, respectively. The MIL-100(In)⊃Tb3+ film shows high oxygen sensitivity (KSV = 7.59) and short response/recovery time (6 s/53 s).

•Luminescent behaviors of lanthanide MOFs are described.•Lanthanide MOFs for luminescence sensing and light-emitting are summarized.•Controllable syntheses of nano-MOFs for sensors are discussed.Metal-organic frameworks (MOFs) have been emerging as very important multifunctional hybrid materials due to their inherent advantages of organic linkers and inorganic metal ions, tunable porosity and diverse functionality. The combination of the intrinsic luminescent features of lanthanide ions together with the unique characteristics of MOFs provides a fascinating opportunity for designing novel luminescent MOF materials. In this review, we summarize our research progress on the design and construction of luminescent lanthanide MOFs, as well as their potential functions and applications on luminescent sensing and light-emitting.

Porous anatase TiO2 has been prepared, for the first time, through the calcination of a metal–organic framework (MOF) precursor under an air atmosphere at 380 °C. The resulting TiO2 has shown moderate porosity with a BET surface area of 220 m2 g−1 attributed to the highly porous structure of the MIL-125(Ti) precursor. The porous anatase TiO2 was examined as a lithium-ion battery anode, exhibiting high capacity retention and good rate capability. The porous structure of anatase TiO2 enforces Li+ diffusion and helps to buffer the volumetric variation. It has shown reversible capacities of 166, 106 and 71 mA h g−1 at 1 C, 5 C and 10 C charge/discharge rates, respectively, after 500 cycles.

By calcination of MOF-74(Ni) under reducing environments, nanosized Ni particles (5–10 nm) in carbon matrices were obtained, which were converted into NiS through an in situ reaction. Featuring small particle sizes (∼50 nm), uniform distribution and porosity, C ⊃ NiS was preliminarily studied as lithium-ion cathode material, which has shown electrochemical performance superior to that of bare NiS.

A new three-dimensional microporous metal–organic framework, Cu2(MFDI) (ZJU-60, H4MFDI = 5,5′-(9,9-dimethyl-9H-fluorene-2,7-diyl)diisophthalic acid), was solvothermally synthesized. ZJU-60 features a three-dimensional structure with a rare sty-a type topology and has two different types of pore apertures. With open metal sites and suitable pore spaces, ZJU-60 can readily separate methane in nearly pure form from CO2 and C2-hydrocarbon quaternary gas mixtures at room temperature with high separation capacity and moderate selectivity. The separation feasibility has been further established by simulated breakthrough and pulse chromatographic experiments.

A novel NbO type microporous metal–organic framework Cu2L (ZJU-32; H4L = 5′-((3,5-dicarboxyphenyl)ethynyl)-[1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylic acid) constructed from an elaborately designed tetratopic ligand was solvothermally synthesized and structurally characterized. The activated ZJU-32a exhibits high permanent porosity with the Brunauer–Emmett–Teller (BET) surface area of 3831 m2 g−1 and the pore volume of 1.482 cm3 g−1, enabling it to be a promising material for both methane storage and carbon dioxide capture at room temperature.

A lanthanide coordination polymer Tb0.957Eu0.043cpda was synthesized as a ratiometric and colorimetric luminescent thermometer. The high triplet excited state energy of a linker enables Tb0.957Eu0.043cpda to detect and visualize temperature over a wide range from cryogenic to room temperature (40–300 K).

A new metal–organic framework with –COOH groups has been realized and demonstrates strong interactions with methylene blue and thus the complete removal of methylene blue from aqueous solution.

A new fluorescent probe, (E)-3-(3-(4-([2,2′:6′,2′′-terpyridin]-4′-yl)phenyl)acryloyl)-7-(diethylamino)-2H-chromen-2-one (ZC-F4), composed of coumarin as the fluorophore and terpyridine as the receptor was designed and synthesized. This probe showed good selectivity and sensitivity towards Zn2+ even at the ppb level with significant variation of emission wavelength (more than 100 nm shifts) after combination with Zn2+. One can observe that the emission colour changed from green to red. A Job's plot test suggested a 1:1 stoichiometry between ZC-F4 and Zn2+, and the theoretical calculation based on density functional theory has been carried out to gain an insight into the sensing mechanism. Furthermore, imaging of Zn2+ in cells was also performed to test its feasibility in biology. This fluorescence probe should be a promising candidate for applications in cell-imaging, environment protection, water treatment and safety inspection.

Hydrocarbons and carbon dioxide are very important raw materials for industrial products and fine chemicals. The microporous metal–organic framework ZJU-25 with high density of open metal sites, has significantly better separation potential than other MOFs, ZIFs or zeolites. It can fractionate a 5-component CH4/C2H2/C2H4/C2H6/CO2 mixture to yield individual pure components as established by the sorption isotherms and simulated breakthrough and pulse chromatographic experiments. Such separations are likely to have a significant industrial impact, resulting in significant energy savings when compared to current technologies that rely on cryogenic distillation.

•A new Li–S cathode using MOFs as host material.•Effective elimination of dissolution problem with high reversible capacity.•Very small charge-transfer resistance using binders with excellent electrical conductivity.Through the melt-diffusion method, S@ZIF-8, a sulfur and metal–organic framework (MOFs) ZIF-8 composite material has been synthesized and utilized as cathode for lithium sulfur battery. Encapsulated into the matrix of ZIF-8, sulfur molecules are restricted in the cages with small apertures and the dissolution problem during the charge/discharge process has been alleviated. Owing to the strong confinement of ZIF-8 matrix to the sulfur molecules inside, the Li–S@ZIF-8 battery shows a reverse capacity of ∼510 mAh/g after 100 cycles at a 0.1 C charge/discharge rate, enabling the S@MOFs materials promising candidates for novel lithium–sulfur battery cathodes.Graphical abstract

A novel NbO type microporous metal–organic framework [Cu2(C26H12O8)(H2O)2]·(DMF)2·(MeCN)3·(H2O)4, (ZJU-7, ZJU = Zhejiang University; H4L = 5,5′-(naphthalene-1,4-diyl)diisophthalic acid; DMF = N,N-dimethylformamide; MeCN = acetonitrile) has been synthesized and structurally characterized. With open metal sites, suitable pore spaces and moderately high permanent porosity, the activated ZJU-7a exhibits moderately high CH4 storage of 160 cm3(STP) per cm3 at 35 bar and 298 K. Meanwhile, ZJU-7a also displays moderate C2H2 gravimetric storage of 180 cm3 g−1 at 1 atm and 298 K.

A new microporous metal–organic framework Cu6(DDCBA)3 (ZJU-72, H5DDCBA = 3,5-di(3′,5′-dicarboxylpheny)-benozoic acid) with open metal sites and exposed carboxylate groups is rationally designed and synthesized, exhibiting a low binding energy of 9.7 kJ mol−1 for C2H2 and 15.1 kJ mol−1 for CO2 and a high separation selectivity of 39.7 for C2H2/CH4 at 298 K and 8.2 for CO2/CH4 at 273 K.

A new mixed lanthanide metal–organic framework thermometer Tb0.9Eu0.1PIA with the significantly high sensitivity of 3.53% per K has been realized by making use of an organic ligand, 5-(pyridin-4-yl)isophthalate, with higher triplet state energy.

A new three-dimensional cationic metal–organic framework Zn8O(EDDA)4(ad)4·(HEDDA)2·6DMF·27H2O (ZJU-48; H2EDDA = (E)-4,4′-(ethene-1,2-diyl)dibenzoic acid; ad = adenine) was solvothermally synthesized and structurally characterized. ZJU-48 features a three-dimensional structure with a cationic skeleton and has one-dimensional pores along the c axis of about 9.1 × 9.1 Å2. The activated ZJU-48a exhibits a BET surface area of 1450 m2 g−1. The structural features of the charged skeleton of ZJU-48a have enabled its stronger charge-induced interaction with C2 hydrocarbons than with C1 methane, resulting in highly selective gas sorption of C2 hydrocarbons over CH4 with the adsorption selectivity over 6 at 298 K. The separation feasibility has been further established by the simulated breakthrough and pulse chromatographic experiments, thus methane can be readily separated from their quaternary mixtures at room temperature.

To immobilize both open metal and Lewis basic pyridyl sites into a microporous metal–organic framework, Cu6(PDC)6·2.6H2O (UTSA-50) was solvothermally synthesized and characterized. The combination of open metal sites and Lewis basic pyridyl functional sites leads to a high acetylene adsorption enthalpy of 39.4 kJ mol−1. As a result, UTSA-50 is a very promising MOF material for the highly selective separation of C2H2/CH4 and C2H2/CO2 at room temperature with the highest C2H2/CH4 separation selectivity of 68 ever reported and moderately high acetylene uptake of 91 cm−1 g−1.

Disposable and miniaturized organic photodiodes with spectral-resolving capabilities are fabricated based on polymeric conductive films doped with cyanine dyes by a drop-on-demand (DoD) inkjet method. The sensitivity and spectral resolution of the photodiodes at the J-aggregate absorption peaks of the corresponding cyanine dyes are improved by at least 800 times after the sequential in situ stacking of inkjet printed functional layers and optimization of the architecture, including the layer thickness and J-aggregate formation. The photodiodes are integratable onto the flowcytometry chips with waveguide laser arrays, demonstrating a spectral-resolving capability of ∼0.1 nm.

A rare sty type microporous metal–organic framework, Cu2(FDDI) (ZJU-25; H4FDDI = tetramethyl 5,5′-(9H-fluorene-2,7-diyl)diisophthalate acid), was solvothermally synthesized and structurally characterized. With open metal sites and suitable pore space for their interactions with methane molecules, ZJU-25a exhibits absolute methane storage of 180 cm3(STP) cm−3 at room temperature and 35 bar, enabling it to be one of the very few porous MOFs whose methane storage capacities have met and/or approached the DOE target of 180 cm3(STP) cm−3 for material-based methane storage.

A new microporous metal–organic framework, Cu2(PDDI) (ZJU-5; H4PDDI = 5,5′-(pyridine-2,5-diyl)diisophthalic acid), was solvothermally synthesized and structurally characterized. With open metal sites, Lewis basic pyridyl sites and suitable pore space, the acetylene uptake in ZJU-5a reaches the highest value of 290 cm3 g−1 at 273 K and 1 bar. Furthermore, ZJU-5a exhibits high absolute methane storage of 190 cm3 (STP) cm−3 at 35 bar and 224 cm3 (STP) cm−3 at 60 bar at room temperature.

Three novel organic dyes containing 2,6-dicarbonyl-pyridine as the central electron acceptor with different end-caped amino groups as donors in the D-π-A-π-D arrangement are designed and synthesized. All three molecules exhibit large TPA cross-sections (δ > 1000 GM). The cooperative effects of donor strength, conjugation length and solvent polarity on the TPA activity are studied. The conjugated system plays an important role on the enhancement of δ in the highly polar solvent, while donor strength has more impact on TPA properties. The influence of the solvent polarity on TPA properties is studied by two-photon excited fluorescence (TPEF) measurement. The result shows a nonmonotonic relationship between the TPA cross-section and the solvent, and the maximum of δ is found in solvents with moderate polarity. The δ of molecules with stronger donor reaches the maximum in more polar solvents. The highest δ is found to be 5250 GM in CHCl3. All compounds exhibit large Stokes shifts due to the strong intramolecular charge transfer (ICT) effect.Highlights► Large TPA cross-section was obtained on three small molecules. ► Strengthened acceptor consisting two strong electron-withdrawing groups. ► Nonmonotonic but regular TPA response towards the variation of solvent polarity. ► Red emission was observed in one of the three molecules.

The lithium–sulfur battery has a very high theoretical capacity and specific energy density, yet its applications have been obstructed by fast capacity fading and low Coulombic efficiency due to the dissolution of polysulfides. Herein we utilize HKUST-1 as the host material to trap sulfur and thus to diminish the dissolution problem. A large amount of sulfur (40 wt %) has been incorporated in HKUST-1 pore metrics to achieve HKUST-1⊃S composite whose structure has been established by both single and powder X-ray diffraction studies. The strong confinement of HKUST-1 for sulfur attributed to the suitable pore spaces and open Cu2+ sites has enabled the resulting Li–S⊂HKSUT-1 battery to show excellent performance with a capacity of about 500 mAh/g after 170 cycles.

A new fluorescence probe for distinguishing Zn2+ and Cd2+ is designed and synthesized. For the first time to our knowledge, this probe can recognize similar metal ions by coherently utilizing intramolecular charge transfer (ICT) and different electronic affinities of various metal ions, instead of by selective coordination alone, which may be interfered with and lose its selectivity easily in a complicated environment, providing a distinct recognition even by the naked eye for Zn2+ and Cd2+ with the sensitivity at the ppb level. This design strategy may initiate a straightforward approach for the selective detection of various metal ions with similar chemical properties in extensive applications such as environmental, industrial, and bio-science.

Various dyes mixtures consisting of perylene red (P-red), pyrromethene 567 (PM567) and coumarin dyes are incorporated into vinyltriethoxysilane (VTES)-derived gel glasses, respectively. Energy transfer processes among dyes are investigated by measuring the time-resolved and steady-state emission spectra, and fluorescence lifetime of each dye. The energy transfer mechanisms are discussed with 4 categories of dye pairs and extended fluorescence lifetime of PM567 and P-red are observed. The radiative and non-radiative nature of the energy transfer processes and their dependence on the donor dye concentration are estimated, paving the way for highly efficient, stable and broadly tunable solid-state dye laser materials.Highlights► Extended fluorescence lifetimes of PM567 and P-red in the presence of donor dyes. ► The energy transfer mechanisms involved can be categorized as 3 kinds. ► The radiative and non-radiative nature of energy transfer varies with PM567 concentrations. ► A multi-photon quenching of triplet PM567 and P-red by coumarin dyes is proposed.

•Two new phenyltetraene-based chromophores with alkylthio group were synthesized.•Inorganic–organic hybrid films are prepared through sol–gel process.•Incorporation of alkylthio group effectively improves the nonlinear optical property.Two new chromophores, CLDS1 and CLDS2, based on a similar D–π–A structure as the phenyltetraene chromophore CLD, but with an alkylthio group perpendicular to the direction of the long molecular axis as isolation spacer were synthesized. Through a urethane forming reaction between 3-isocyanatopropyltriethoxysilane (ICTES) and chromophores, the alkoxysilane dyes were synthesized. Subsequently, a series of transparent and homogeneous inorganic-organic hybrid films were prepared via a sol–gel process of the alkoxysilane dye with triethoxyvinylsilane. The molecular structures of the resultants were confirmed by 1H NMR, FTIR and UV–visible spectra. After electric poling, the nonlinear optical coefficients (d33) of the hybrid films F-CLDS1 and F-CLDS2 were determined to be 104.54 and 98.17 pm V−1, respectively, which are almost 3 times the d33 value of hybrid film containing CLD (37.78 pm V−1), indicating that the incorporation of alkylthio group can efficiently improve the macroscopic optical nonlinearities of hybrid materials.

•A new fluorescent and colorimetric probe with strong ICT effect.•Significant fluorescence enhancement and changes in color toward hydrazine.•High sensitivity at ppb level with a detection limit lower than that regulated by EPA.•Wide range detection resulted from large conjugated system.A new fluorescent and colorimetric probe based on the reaction and intramolecular charge transfer (ICT) effect is designed and synthesized. The probe responds rapidly toward hydrazine and exhibits distinct color changes from yellow to colorless, indicating its use as a color indicator for hydrazine. Moreover, the probe also shows a significant broad band fluorescence (410–700 nm) enhancement by ∼120-fold after the addition of hydrazine. With a detection limit as low as 0.11 ppb, the probe can detect hydrazine in a wide concentration range because of the blunted sensing functional group. The contrast test shows almost no interruption from common elements in water, suggesting the high selectivity of this probe toward hydrazine. The theoretical calculation based on density functional theory (DFT) is also performed and two different ICT modes are found. This hydrazine probe would be a promising candidate applicable in environment protection, water treatment and safety inspection.

•A new metal–organic framework (ZJU-26) was synthesized.•ZJU-26 displays large adsorption enthalpies of 32.7 kJ/mol for C2H2.•ZJU-26 exhibited high separation selectivity for C2H2/CH4 and C2H2/CO2.A new three-dimensional micro-porous metal–organic framework Cu2(ADDI) (ZJU-26; H4ADDI = 5,5′-(anthracene-2,6-diyl) diisophthalic acid) with open metal sites and suitable pore space for their interactions with acetylene molecules was solvothermally synthesized and structurally characterized. ZJU-26 reveals a three-dimensional structure having hexagonal pores of about 5.0 Å along the c axis and irregular pores of about 3.4 × 8.5 Å2 along the a or b axis. Due to the introduction of anthracene ring do significantly enlarge pore size along a/b axis and enhance the interaction between MOF and acetylene, ZJU-26 indicates large adsorption enthalpies of 32.7 kJ/mol for C2H2 and moderately high acetylene uptake of 84 cm−1/g, highlighting ZJU-26 as the highly selective microporous metal organic framework for the C2H2/CH4 and C2H2/CO2 gas separation with separation selectivity of 45.9 and 12.5 at room temperature.

•Continuous In-BTC films were prepared using in situ solvothermal synthesis method.•The Pt nanoparticles improve the heterogeneous nucleation and growth of In-BTC films.•Luminescent films were achieved by post-functionalizing In-BTC with lanthanide ions.•Luminescent films show good performance in fast detection of thiol vapors.Continuous and well-attached thin films of indium trimesate metal–organic framework (MOF) were prepared rapidly by in situ solvothermal synthesis method on silicon wafer modified with platinum nanoparticles. The film growth process and possible mechanism were studied in detail. Luminescent metal–organic framework thin films, In-BTC⊃Ln, were achieved by the post-functionalization of the resulted MOF film In-BTC with lanthanide ions (Eu3+, Tb3+, Dy3+ or Sm3+). The structure and morphology of the films were investigated by XRD and SEM. The luminescent properties of the In-BTC⊃Ln films indicate that lanthanide ions are sensitized by organic linker via the metal carboxylates in the pores. More interestingly, the luminescent In-BTC⊃Ln films show good performance in fast detection of volatile thiols such as 1,2-ethanedithiol and 1-butanethiol.Continuous luminescent MOF films, In-BTC⊃Ln were achieved by the post-functionalization of In-BTC films with lanthanide ions. And luminescent films show good performance in fast detection of vaporous thiols.

A BA-derived fluorescent pH sensor for use under strongly acidic conditions based on the ICT effect was realized to exhibit high stability, sensitivity and selectivity. This probe can be used to detect acidity within the pH range 0.5–2.5. The design strategy may help to develop probes for targets at high concentrations.

•A new chemosensor based on the ortho-methylation of boron-dipyrromethene.•Fluorescent “turn-on” detection for HTM ions with high sensitivity and selectivity.•The detection upper limit for Ag+ is as low as 1.2 ppm.•The ortho-methyl group enhances the quantum efficiency and detection sensitivity.A fluorescent chemosensor, ortho-methylated boron-dipyrromethene (o-MBDP) has been synthesized and characterized. It featured excellent selectivity and sensitivity for Ag+ and Hg2+ ions, which could enhance the weak fluorescence of o-MBDP drastically by several hundred times through coordination and as a result, behave as an efficient “turn-on” fluorescent probe. The detection upper limit for Ag+ ion could be decreased by at least one order of magnitude with the introduction of the ortho-methyl group, in comparison with analogous boron-dipyrromethene (BDP) sensors, indicating the feasibility in extensive application areas as chemosensors.

In this work, the laser dye PM567 was incorporated into various organically modified silicate gel glasses (ORMOSILs) derived by methyltriethoxysilane (MTES) and vinyltriethoxysilane (VTES) precursors mixed in various ratios. The laser performances of PM567 doped into MTES–VTES-derived ORMOSILs including the laser slope efficiency, threshold and lifetime together with the spectroscopic properties were investigated. Blue-shifts of fluorescent peaks, extended fluorescent lifetime, improved laser efficiency and lifetime of PM567 doped into ORMOSILs derived by mixed precursors of MTES and VTES have been observed, which might related to the microstructures and micro-chemical environment of the dye in ORMOSILs.

•Inorganic-organic hybrid films are prepared via sol-gel process of alkoxysilane dyes•Nonlinear optical properties of hybrid films are investigated•Fluorinated benzene group effectively improves the nonlinear optical propertyTwo azo chromophores containing fluorinated benzene and alkyl chain as isolation group were designed and synthesized, respectively, and the corresponding alkoxysilane dyes were obtained by coupling 3-isocyanatopropyltriethoxysilane with the chromophores. The molecular structures were verified by elemental analysis, hydrogen nuclear magnetic resonance, and Fourier transform infrared spectrum. Followed by a sol–gel process of the alkoxysilane dyes, inorganic–organic hybrid films were prepared by spin-coating. After electric poling, these hybrid films show the higher nonlinear optical (NLO) response than their analog containing chromophore DR1. Furthermore, the fluorinated benzene group exhibits better enhanced effect than the flexible alkyl group. The highest NLO coefficients (d33) of the hybrid film containing fluorinated benzene group was determined to be 140.5 pm V− 1 at the chromophore concentration of 40%.

•Continuous indium metal-organic framework thin films are prepared.•The growth process and the possible growth mechanism of thin films are investigated.•Indium tin oxide glass promotes the homogeneous nucleation of thin films.Continuous indium metal-organic framework thin films of In12O(OH)12[(OH)4·(H2O)5)][BTC]6 (MIL-96(In)) (BTC = 1,3,5-benzenetricarboxylate) were prepared on indium tin oxide glass by in situ solvothermal growth method. The structure of the films was confirmed by X-ray diffraction. The growth process and the possible growth mechanism of MIL-96(In) films were investigated by a scanning electron microscopy. Furthermore, the influence of the reaction conditions on the morphology and thickness of films was studied. The best crack-free, continuous film with thickness of approximate 6 μm was obtained at the proper concentrations of InCl3 and H3BTC of 25.0 mmol·l− 1 at 100 °C for 12 h.

A luminescent mixed lanthanide metal–organic framework approach has been realized to explore luminescent thermometers. The targeted self-referencing luminescent thermometer Eu0.0069Tb0.9931-DMBDC (DMBDC = 2, 5-dimethoxy-1, 4-benzenedicarboxylate) based on two emissions of Tb3+ at 545 nm and Eu3+ at 613 nm is not only more robust, reliable, and instantaneous but also has higher sensitivity than the parent MOF Tb-DMBDC based on one emission at a wide range from 10 to 300 K.

Three new six-branched chromophores with different isolation groups were designed and synthesized by incorporating azo chromophores onto phenyl glycerol ester via an esterification reaction. The chemical structures were confirmed by 1H NMR, 13C NMR, FT-IR spectroscopy, mass spectrometry, element analysis and UV-visible absorption spectra. The six-branched dendritic chromophores can form thin films directly without adding any polymer matrix and show a quite high chromophore loading density. After electric poling, the nonlinear optical coefficients (d33) of the dendrimer films were determined to be around 113, 142 and 136 pm V−1, which are almost 3 times the maximum d33 value of the azo-chromophore doped polymer films. The further improvement in optical nonlinearity was successfully realized by mixing the six-branched chromophores containing different isolation groups.

A microporous metal–organic framework MOF 1 [Zn(L)2(methanol)2] (H2L = (1R,3S)-1,2,2-trimethyl-3-(pyridin-4-ylcarbamoyl)cyclopentanecarboxylic acid) constructed from a flexible Zn2+ node and a flexible organic linker L was obtained by solvothermal reaction of diamond topology, and exhibits highly selective sorption of methanol over ethanol and water.

We have realized a rational design strategy to construct isostructural Tb3+ and Eu3+ doped lanthanide metal–organic framework materials whose colors can be easily tuned by the different combination of the doped Tb3+ and Eu3+ concentrations, generating white light emitting materials.

A nanoscale MOF material NMOF 1 with controllable morphologies is realized whose morphology control has been simulated based on the BFDH method. The targeted NMOF 1 exhibits highly sensitive, selective and instant “turn-on” sensing of bacterial endospores.

The reaction between polyoxometalate (POM) [TBA]12[WZn{Zn(H2O)}2(ZnW9O34)2] (TBA = tetrabutyl ammonium) and lanthanide (Ln) nitrate (Ln = La, Eu and Tb) in a mixed solvent of CH3CN and DMF yielded three noncentrosymmetric diamondoid Ln–POM solid materials, {[Ln2(DMF)8(H2O)6][ZnW12O40]}·4DMF (Ln–POM; Ln = La, Eu and Tb). In these compounds, the {ZnW12O40} unit, transferred from the metastable [WZn{Zn(H2O)}2(ZnW9O34)2] cluster, acts as a tetradentate ligand to connect with four Ln nodes, while the Ln ion links up two {ZnW12O40} units. These compounds generated interesting luminescence emissions that are dependent on the Ln ions and their ratios. White light emission was obtained by a doped approach with a rational ratio of the Eu3+ and Tb3+ ions.

A new six-branched chromophore GGQ1 is designed and synthesized via the incorporation of an FTC-type chromophore 1 with phenyl glycerol ester. The six-branched chromophore GGQ1 shows a large molecular weight of 3834 Daltons and can directly form thin films with quite high active chromophore loading density. For comparison, guest–host doped polymer films are fabricated by doping chromophore 1 and BF1 into poly(4-vinylphenol). All of these doped films show a saturated trend in second harmonic generation coefficient (d33) and a maximum d33 value between 50–70 pm V−1 around the doping concentration of 25 wt%, due to the strong interchromophore electrostatic interactions. In contrast, GGQ1 films display a d33 value of 192 pm V−1. The results indicate that the six-branched chromophore could efficiently reduce the interchromophore electrostatic interactions and enhance the macroscopic optical nonlinearity, showing promise for applications in nonlinear optical (NLO) materials.

A doubly interpenetrated semiconducting MOF Zn4O(2,6-NDC)3(DMF)1.5(H2O)0.5·4DMF·7.5H2O (UTSA-38) of a cubic net has been constructed, which exhibits photocatalytic activity for the degradation of methyl orange in aqueous solution.

The first nanoscale luminescent metal–organic framework has been realized for the straightforward and highly sensitive sensing of nitroaromatic explosives in enthanol solution.

A novel fluorescence chemosensor based on 2,6-dicarbonylpyridine was designed and synthesized and its photophysical properties were characterized. Upon coordination of Co2+ by the central 2,6-dicarbonylpyridinyl functional group, the chemosensor 2,6-bis(4-diphenylamino-styrylcarbonyl)pyridine (PhPy) showed nearly complete fluorescence quenching, while no fluorescence response was seen towards other competing cations. The experimental results show the chemosensor is highly selective and sensitive towards Co2+ in the presence of competing ions, even in the ppb range. Job plot analysis was carried out and the results suggested that the binding of PhPy and Co2+ was probably a 2:1 stoichiometry.

A new nonlinear optical (NLO) chromophore 4-dicyanomethylene-2-methyl-6- {4-[4-(N-ethyl-N-hydroxyethylamino)phenylazo]}styryl-4H-pyran (AZP), which features extended conjugated chain based on DCM laser dye, was synthesized and functionalized with alkoxysilane for materials processing. Hybrid films containing chromophore AZP and DCM were prepared via a sol–gel processing. The d33 values of films containing AZP are 39-48 pm/V varying with concentration of chromophores, which is similar to that containing DCM. By tuning the organic content, the thermal stability of d33 values can be significantly improved by about 30 °C, about 15 °C higher than those containing DCM. The residual rotational stress, along with cavity between chromophores and matrix, is proposed to contribute to the stability of NLO activity of hybrid films.

A thiophene-vinyl conjugated FTC-type chromophore was synthesized and reacted with 3-isocyanatopropyltriethoxysilane to form alkoxysilane dye. The structure of alkoxysilane dye was confirmed via elemental analysis, FTIR and 1H NMR. Stable and transparent hybrid films were fabricated following sol–gel process of alkoxysilane dye and tetraethoxysilane. The second harmonic generation coefficients (d33) of the hybrid films were measured via in situ second harmonic generation measurement. The d33 value of hybrid films was calculated to be 43 pm V−1 when the chromophore loading density was 20 mol%. Furthermore, the thermal stability of optical nonlinearity was also investigated through a depoling experiment, showing a half decay temperature of 165 °C.

Molecular recognition, an important process in biological and chemical systems, governs the diverse functions of a variety of enzymes and unique properties of some synthetic receptors. Because molecular recognition is based on weak interactions between receptors and substrates, the design and assembly of synthetic receptors to mimic biological systems and the development of novel materials to discriminate different substrates for selective recognition of specific molecules has proved challenging. The extensive research on synthetic receptors for molecular recognition, particularly on noncovalent complexes self-assembled by hydrogen bonding and metal−organic coordination, has revealed some underlying principles. In particular, these studies have demonstrated that the shapes of the supramolecular receptors play significant roles in their specific and selective recognition of substrates: receptors can offer concave surfaces that complement their convex targets. This Account describes our research to develop a synthetic molecular recognition platform using porous metal−organic frameworks (MOFs). These materials contain functional pores to direct their specific and unique recognition of small molecules through several types of interactions: van der Waals interactions of the framework surface with the substrate, metal−substrate interactions, and hydrogen bonding of the framework surface with the substrate. These materials have potential applications for gas storage, separation, and sensing. We demonstrate a simple strategy to construct a primitive cubic net of interpenetrated microporous MOFs from the self-assembly of the paddle-wheel clusters M2(CO2)4 (M = Cu2+, Zn2+, and Co2+) with two types of organic dicarboxylic acid and pillar bidentate linkers. This efficient method allows us to rationally tune the micropores to size-exclusively sort different small gas molecules, leading to the highly selective separation and purification of gases. By optimizing the strong interactions between open metal sites within porous MOFs and gas molecules such as hydrogen and acetylene, we have developed several MOF materials with extraordinary acetylene storage capacity at room temperature. We have also immobilized Lewis acidic and basic sites into luminescent porous MOFs to recognize and sense neutral and ionic species. Using the strategy to systematically immobilize different open metal sites within porous MOFs from the metalloligand precursors, we have developed the first microporous mixed-metal−organic framework (M′MOF) with enhanced affinity for hydrogen molecules, which successfully separated D2 from H2 using kinetic isotope quantum molecular sieving. Because we can functionalize the pores to direct their specific recognition of small molecules, the emerging porous MOFs serve as novel functional materials for gas storage, separation, heterogeneous catalysis, and sensing.

A microporous MOF [Zn4(OH)2(1,2,4-BTC)2] (1,2,4-BTC = Benzene-1,2,4-tricarboxylate) with two immobilized open metal Zn2+ sites was obtained by solvothermal reaction, which exhibits highly selective guest sorption and sensing of nitrobenzene.

A luminescent metal–organic framework with small micropores for the enhanced recognition of Cu2+ exhibits highly sensitive and selective sensing of Cu2+ in aqueous solution.

A rare uninodal 9-connected metal−organic framework (Zn3(TAA)3(H2O)3·(1,4-dioxane) (MOF 1) (TAA = 1-H-tetrazole-5-acetate) was synthesized, structurally characterized, and topologically rationalized as a vnd net, exhibiting permanent porosity, and solvent-dependent luminescence properties.

Two new chiral two-dimensional coordination networks, ZnL2(H2O)2 (1) and CdL2(H2O)2 (2) [L = 1,2,2-trimethyl-3-(pyridin-4-ylcarbamoyl)cyclopentanecarboxylic acid], have been synthesized and structurally characterized by single X-ray structure analysis, featuring very unusual interwoven (4,4) square grids of double helices. The frameworks exhibit high thermal stability as confirmed by thermogravimetric analysis and powder X-ray diffraction studies. The unique chiral networks attributed to the chiral organic linker have led to their nonlinear optical properties.

The structure of a novel bichromophore that comprised a readily hyperpolarisable chromophore with 3-phenoxypropane-1, 2-diol via esterification, was confirmed by elemental analysis, UV–visible absorption spectra and 1H NMR. Nonlinear optical polymer films were fabricated by doping the bichromophore and the corresponding monochromophore into poly(4-vinylphenol). In situ second harmonic generation measurements revealed that the bichromophore imparted a 2.2-fold enhancement in the second harmonic generation coefficients of the films, indicating that the novel 3-phenoxypropane-1, 2-diol derivative could be used in the design and synthesis of multi-chromophoric dendrimers with large macroscopic optical nonlinearity.

An azo-chromophore containing 2-methylidene-3-(dicyano-methylidene)-1-indanone as electronic acceptor group was synthesized via the Knoevenagel condensation between an aldehyde and indanedione derivative, followed by reaction with 3-isocyanatopropyltriethoxysilane. The structures of the chromophore and the synthesized alkoxysilane dye were confirmed by means of elemental analysis, NMR and FTIR analyses. Thermal analysis revealed that both had distinct melting points and thermal stability up to 240 °C. The chromophore and alkoxysilane dye are readily soluble in common solvents such as DMF, THF and DMSO. Compared with the traditional dye C.I. Disperse Red 1, the indanone-based chromophore exhibited larger molecular hyperpolarizability owing to its stronger electron-withdrawing ability.

An alkoxysilane precursor based on imidazole chromophore, namely 2-((4-(ethyl(2-hydroxyethyl)amino)phenyl)diazenyl)-4,5-dicyano-1H-imidazole (IZ), has been successfully synthesized through a urethane forming reaction. Following a sol–gel process of the resultant precursor, inorganic–organic hybrid films were obtained by spin-coating. Their structures were verified by 1H NMR, FT-IR, UV–vis spectra and elemental analysis. After corona poling, the electro-optic (EO) properties of the hybrid films were characterized by a simple reflection technique, and the EO coefficient (r33) of a sample was determined to be 1.6 pm/V at a wavelength of 1310 nm.

Two azole heterocycle-contained chromophores, named EBTC and EBOC respectively, were synthesized and then reacted with 3-isocyannatopropyltriethoxysilane (ICTES) to form functionalized alkoxysilane dyes (ASDs) which were named as ASD-EBTC and ASD-EBOC, respectively. Sol solutions were obtained after co-hydrolysis/condensation of ASD and tetraethoxysilane (TEOS). Second-order nonlinear optical (NLO) inorganic–organic hybrid films were successfully prepared via sol–gel process. The second harmonic coefficients (d33) of poled hybrid films were measured by a Maker fringe technique. The d33 values obtained for the EBTC and EBOC films are 23.7 and 9.3 pm/V, respectively. The hybrid film containing benzothiazole exhibited better NLO properties than its analogue containing benzoxazole.

A family of second-order nonlinear optical sol–gel films with a pendent thiophene chromophore has been developed. The key step in preparation these hybrids was the syntheses of alkoxysilane dye containing thiophene ring, which was accomplished by utilizing the urethane forming reaction. Molecular structural characterization for the resultant was achieved by FTIR, 1H NMR and UV–Visible spectra. The microscopic optical nonlinearity of the thiophene chromophore was evaluated to be 7646 × 10− 30 esu D by solvatochromic method and second harmonic coefficients (d33) of the hybrid film was also calculated to be 41.2 pm/V by second harmonic generation (SHG) measurements, respectively. Furthermore, the stability of optical nonlinearity in poled film was also investigated through a depoling experiment.

A new hetero-trichromophore (HT-1) was designed and synthesized by linking neutral-ground-state (NGS) chromophore 1 with zwitterionic (ZWI) chromophore 2, and their molecular structures were confirmed by elemental analysis, UV−vis absorption spectra, 1H NMR, etc. Theoretical calculations show that there is a decrease of molecular dipole moments in gas phase when chromophores 1 and 2 are linked together. The polymer films were fabricated by doping trichromophore HT-1, NGS chromophore 1, and ZWI chromophore 2 into poly(4-vinylphenol) (PVPh). The second harmonic generation coefficients (d33) of the films and the thermal stability of optical nonlinearities were measured by in situ second harmonic generation (SHG) measurement. The results show that almost a 5-fold enhancement in second harmonic coefficients (d33) is realized as the combination of NGS chromophore and ZWI chromophore. The results indicate that NGS and ZWI chromophore combined hetero-trichromophores can efficiently improve the macroscopic optical nonlinearities in poled polymer materials.

A series of novel inorganic−organic hybrid materials with benzimidazole chromophores covalently bonded into the inorganic silica network as pendants has been designed and synthesized via the wet chemistry routes. The measurement results of solvatochromic method and UV−vis spectra indicate that these benzimidazole chromophores exhibit higher microscopic optical nonlinearity compared with their analogues with benzene ring and without undesirable red-shift of the absorption band. After corona poling, the macroscopic nonlinear optical activity and poling alignment stability of the hybrid films were investigated by in situ second harmonic generation measurement. These hybrid films exhibit enhanced nonlinear optical coefficient from 25 to 54 pm/V with chromophore concentration varied, improved optical transparency (λmax < 470 nm), as well as excellent polar orientation stability at 160 °C.

A DCM derivative, namely 4-Dicyanomethylene-2-methyl-6-{[4′-(N-hydroxyethyl-N-methyl)amino]styryl}-4H-pyran (DCMH), has been synthesized and covalently incorporated into the inorganic silica network as pendants via a sol–gel process. Molecular structures of the resultants are confirmed by elemental analysis, 1H NMR, DSC, TGA, FTIR and UV–Vis spectroscopy. Photoluminescence (PL) spectra shows that the emission of DCMH peaked at 625 nm is almost completely quenched in DMF solution with a concentration of 1 × 10−4 mol/L, however, in hybrid films, the PL intensity enhances obviously with increasing DCMH concentration even at the high loading content of 40 mol%. All the hybrid films exhibit PL emission around 646–650 nm and the peak position reveal little dependence on the concentration of dye, suggesting they can be used as red emissive materials in light-emitting diodes. The relationship between fluorescence lifetime and dye concentration is also investigated by time-resolved PL measurements.

The sol–gel technique has been used to prepare a thin film for second-order nonlinear optics (NLO). An azo-dye molecule 2,5-dimethyl-4-(4′-nitrophenylazo)phenol (DMNPAP) was covalently bonded to the silicon oxide network through hydrolysis and co-condensation between the alkoxysilane dye and tetraethyl silicate (TEOS) in relatively high loading densities (43 wt%). The resulting film showed a thermal stability up to 302 °C in thermogravimetric analysis (TGA) thermograms and a flat surface morphology in atomic force microscope (AFM) image. The orientation behavior of the poled film was studied by UV–visible spectroscopy. The NLO activity (d33), which was estimated to be 6.5 pm/v at 1064 nm by in situ second harmonic generation (SHG) measurement, the thermal stability of the second-order nonlinearity was also reported.

Laser dyes such as pyrromethene 567 (PM567), perylene red (P-red) and coumarin 540A (C540A) were doped into zirconia-organically modified silicate (ORMOSIL) materials prepared by low temperature sol–gel technique. Narrow line-width distributed feedback (DFB) laser actions were induced in the PM567 and/or P-red doped sol–gel planar waveguide. Tuning of the output wavelength was achieved by varying the period of the gain modulation generated by a nanosecond Nd:YAG laser at 532 nm. Compared with those of PM567 and P-red solely doped thin films, tuning range of C540A, PM567 and P-red co-doped sol–gel planar waveguide was greatly extended, from 564.5 nm to 635.1 nm.

A nonlinear optical (NLO) chromophore (2-(3-cyano-4-(4-((2-hydroxyethyl)(methyl)amino) styryl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile, abbr. FS) and a hole-transporting molecular ((4-(diphenylamino)phenyl)methanol, abbr. TPA) were synthesized and reacted with (3-isocyannatopropyl) triethoxysilane (ICTES) to form two functionalized silicon alkoxide precursors (named ICTES-FS and ICTES-TPA, respectively). Sol solutions were obtained after co-hydrolysis/condensation of tetraethoxysilane, ICTES-FS and ICTES-TPA. Transparent films were only fabricated with the sol containing ICTES-TPA. Thermal stabilities and aggregation behaviors of the NLO chromophores in hybrid films were studied by ultraviolet–visible spectra. ICTES-TPA units with triphenylamine groups at high concentration were found useful to abate dipolar chromophore interactions and consequent aggregation problems. Second-order NLO properties and temporal stabilities of sol–gel films were also investigated by virtue of in-situ second harmonic generation.

In this paper, second-order NLO chromophores containing two reactive sites have been synthesized and characterized by 1H NMR, FTIR and elemental analysis. The transparent films have silica network of matrix and covalently bonded chromophore of NLO segment were then fabricated via sol–gel process. The SHG coefficients (d33) of the poled films were calculated to be around 50 pm/V by in situ second harmonic generation (SHG) measurement. The thermal stability of the NLO coefficient was investigated by the depoling experiment and temporal decay test, showing that the cross-linked films had a good thermal stability up to 160 °C.

A series of organically modified sol–gel films with various acceptor groups were prepared and characterized. All the chromophores exhibit much larger microscopic optical nonlinearity compared with the classical chromophore DR1 in solvatochromic measurement. Using in situ second harmonic generation (SHG) technique, the optimal poling temperatures (Topt) for sol–gel films were obtained. The second harmonic coefficients (d33) of hybrid films at the wavelength of 1,064 nm were in the range of 50.1–70.3 pm/V after corona poling under their Topt. The NLO stabilities of these poled films were also investigated by tracing the d33 value as a function of temperature and time. One of the hybrid films, which was prepared from chromophore 2,4-dinitro-4′-(N,N-dihydroxyethyl) aminoazobenzene exhibited a combination of large optical nonlinearity and high NLO stability. Furthermore, the effects of molecular structure on the NLO property and thermal stability of the hybrid films were also discussed.

Organic–inorganic hybrid films containing nonlinear optical (NLO) active chromophores were prepared through the polyaddition of methacrylate and hydrolytic polycondensation of sila-functional alkoxy groups of 3-(trimethoxysilyl)propyl methacrylate (TSPM) which is capable of forming carbon–carbon and siloxane chains, respectively. The NLO-active chromophores are designed and synthesized to be covalently grafted to the carbon–carbon or the siloxane chains. The comparative study of the two different incorporation methods reveals that the poled hybrid film with NLO-active chromophores bonded to siloxane chains would possess a more stable dipolar orientation.

Near infrared dye, IR26, was doped into zirconia-organically modified silicate (ORMOSILs) waveguides by sol–gel technique. Amplified spontaneous emission (ASE) centered at 1.14 μm was observed from the solid films and their spectroscopic characteristics were studied. The dependence of ASE on the preparation details was discussed. The threshold and full widths at half maximum (FWHM) of ASE were 8.6 mJ/cm2 and ∼15 nm, respectively. The output intensity dropped to 50% of its initial value after 1,200 pulses at a repetition rate of 10 Hz and pump intensity of higher than 50 mJ/cm2. These materials are promising for the distributed feedback (DFB) lasers tunable in infrared.

Rare earth ternary chelates Ln(TFA)3(TPPO)2 (Ln = Eu, Tb and Eu/Tb) were synthesized in gel glasses via in situ technique. Pure Ln(TFA)3(TPPO)2 chelates were also synthesized for a comparative study. Photoluminescence properties of the in situ chelates in gel glasses and the pure chelates were studied. In order to investigate the energy transfer mechanism from Tb3+ ions to Eu3+ ions in Eu/Tb(TFA)3(TPPO)2 chelates, photoluminescence spectra and fluorescence decay curves have been measured at the temperature range from 10 K to 293 K. It is found that the energy transfer rate constants calculated from the fluorescence lifetimes do not vary with temperature, which suggests that Dexter mechanism is responsible for the energy transfer from Tb3+ ions to Eu3+ ions in both pure and in situ Eu/Tb ternary chelate.

We show an inorganic–organic hybrid silica gel glass with remarkable femtosecond optical Kerr effect in the order of the time-resolution of the experiment (∼200 fs) based on doped lead phthalocyanine. In our materials, self-diffraction of the pumping beam by ultrafast transient gratings dominates the Kerr signal, ensuring ultrafast response happens. By the replacement of inorganic or polymeric matrix with inorganic-organic hybrid, many practical advantages can be gained. Our results demonstrate a critical role for the design of novel ultrafast optical Kerr shutters in such low-cost silica based-nanocomposites with great flexibility.Femtosecond optical Kerr effect in lead phthalocyanine doped inorganic–organic hybrid materials has been demonstrated. Time-resolved optical Kerr signal decay experiment shows the ultrafast response process dominating over the decay process and the slow decay process is restrained effectively compared with that for CS2 solution.

Multiphoton-induced two-dimensional periodic microstructures were fabricated in dye-doped bulk transparent materials by four-beam interference of femtosecond pulses at a wavelength of 800 nm. Observations of optical microscopy show that two-dimensional microstructures are realized in the samples through nonresonant absorption process. The photoinduced refractive index modulation, resulted from the multiphoton-induced photodecomposition, is responsible for the periodic microstructures. These results suggest that this method can be applied to a wide variety of transparent materials and that the materials co-doped with different dyes and with photoinduced microstructure may be possible to make the distributed feedback lasers with novel properties.Two-dimensional microstructures of square lattices with a period of 6.4 μm have been induced in dye-doped inorganic-organic hybrid materials by four-beam interference of femtosecond pulses. The formation of the microstructures is due to the multiphoton-induced photodecomposition of the dye molecules. The method may find applications in functional optoelectronic devices.

Hybrid inorganic–organic second-order nonlinear optical (NLO) materials have been obtained through hydrolysis and co-condensation between tetraethyl silicate (TEOS), Vinyltriethoxysilane (VTES) and an alkoxysilane dye (ICTES-DR1). The hybrid materials showed a thermal stability up to 306 °C in thermogravimetric analysis (TGA) thermograms and no visible glass transition temperature (Tg) was observed in the range 50–200 °C in differential scanning calorimetry (DSC) thermograms. The poling profiles of the hybrid films were investigated by using the in situ second harmonic generation (SHG) measurement. The thermal stability of the second order NLO properties of the poled films were also investigated by the in situ SHG intensity probing. It has been shown that the NLO response and its thermal stability were strongly dependent on the thermal pretreatment of the films.

Silver nanoparticles of 20 and 70 nm, respectively, were deposited on the surfaces of submicron silica spheres. Plasma resonances of the submicron silica spheres with dense and uniform silver layer were investigated using UV/vis absorption spectra. It was found that the silver plasma resonance band of the silica–silver core-shell spheres was broadened and shifted to longer wavelength several hundreds nanometers. The dipole–dipole interactions of neighboring silver particles and Mie scattering of silver shell as a whole may serve as the mechanism of such shift and broadening.

Silica layer and silver layer were successively deposited on the surface of submicron silica spheres through electroless plating approach to fabricate multilayer-coated core–shell structural monodisperse spheres, SiO2@Ag@SiO2, for photonic crystals use. High quality silver layer with dense and uniform structure was verified by UV–visible absorption spectra and energy dispersive X-ray microanalysis (EDX). The metal-dielectric spheres SiO2@Ag@SiO2 with 300 nm in diameter crystallize directly into close-packed structure by self-organisation method, and directional photonic band gaps (PBGs) for the photonic crystal were found in optical and near infrared wavelengths.

Dense, uniform and thickness controllable silver layers were successfully coated on the mono-dispersed submicrometer silica spheres to obtain silica–silver core-shell structural spheres. The growth process of nanoscaled silver layer on silica spheres mainly includes two steps, i.e. nanoscaled nuclei formation and controllable layer growth process. The nuclear-growth mechanism is responsible for the deposition processes. The reagent concentrations and reaction time were found to be the key factors for the formation of controllable silver layer. High quality silver layer with dense and uniform structure was verified by transmission electron microscopy, X-ray diffraction and Energy Dispersive X-ray microanalysis.

Near-infrared (NIR) luminescent ternary and hydrated binary neodymium β-diketonates emitting at ca. 1330 nm are presented. The effects of ligand moieties on the photoluminescence properties of Nd3+ ions are discussed. Moreover, the neodymium organic complex neodymium tris(2-theonyltrifluoroacetonate)bis(triphenylphosphine oxide), Nd(TTA)3(TPPO)2, which has the best photoluminescence properties among all investigated neodymium complexes, is incorporated into vinyltriethoxysilane-derived ORMOSIL (organically modified silicate) film by a multistep sol–gel process. The Nd doping concentration was up to 5 mol% related to Si. The spectroscopic results about as-doped ORMOSIL films indicate that the ligands around Nd3+ ions indeed shield effectively Nd3+ ions from luminescence-quenching impurities in the host matrix, such as OH groups.

Vinyltriethoxysilane-derived organically modified silicate (ORMOSIL) films doped with the organic complex neodymium tris(2-theonyltrifluoroacetonate)bis(triphenylphosphine oxide) by a multistep sol–gel process exhibit near-infrared luminescence at ca. 1330 nm (4F3/2→4I13/2). Spectral properties of as-doped films with a series of doping concentration from 1 to 10 mol.% (Nd related to Si) are investigated for the optimum doping concentration. The vinyltriethoxysilane-derived ORMOSIL host matrix is considered to have little effect on spectral properties of Nd3+ ions due to the ligands' protection. The effect of heat-treatment on photoluminescence properties is also revealed.

Laser dyes such as coumarin 440 (C440) and coumarin 500 (C500) were doped into vinyltriethoxysilane (VTES)-derived organically modified silicates (ORMOSILs) by sol–gel process. The fluorescence properties of these two dyes doped in VTES-derived ORMOSILs with various initial dye concentrations were studied. A longitudinal pumped solid-state dye laser was established with a Q-switched Nd:YAG laser source. The laser performances of C440 and C500 dyes doped in VTES-derived ORMOSILs were also measured.

Laser dyes such as rhodamine B, rhodamine 6G, pyrromethene 567, perylene orange and perylene red were doped into GPTMS-, MTES- and VTES-derived organically modified silicates (ORMOSILs) by sol–gel process. A longitudinal pumped solid-state dye laser was established with a Q-switched Nd:YAG laser source. The lifetimes of these dyes in various ORMOSILs were investigated by using such an experimental setup at a pump repetition rate of 2 Hz and pump intensity of 0.1 or 1.4 J/cm2. The lifetime of 60 000 pulses, 50 GJ/mol in normalized photostability, was obtained for the pyrromethene 567 doped in MTES-derived ORMOSIL with the net sample thickness of 4 mm when its output energy declined to 50% of its initial value. The slope efficiencies of pyrromethene 567 and perylene orange in various host media were also measured.

In this work, laser dye pyrromethene 567 (p567) was doped into methyltriethoxysilane (MTES)-derived organically modified silicate (ORMOSIL) monolith with various photo-stable additives including 1,4-diazobicyclo[2,2,2]octane (DABCO), 2,2,6,6-tetramethylpiperdin (TMP) and coumarin 440 (C440). The photostability of p567 was determined under continuous ultraviolet irradiation and its dependence on the concentration of each additive was studied. The results illustrated that the photostability of p567 in ORMOSIL with the optimized concentration of DABCO or TMP was improved by at least 100%. The highest photostability of p567 was obtained with the presence of C440, where at least four times of improvement has been observed. The photo-stable mechanisms of additives have also been discussed.

Azodye-doped vinyl group substituted bulk silica materials were prepared by a sol–gel method. Photoinduced noncentrosymmetry in these initially centrosymmetric rigid matrixes was demonstrated first using nonresonant all-optical poling with a fundamental light at wavelength of 1500 nm and its second-harmonic light. The largest photoinduced second-order nonlinear optical coefficient d33 was estimated to be 8×10−3 pm/V. The characteristic kinetics of decay of the induced second-order susceptibility was measured by second-harmonic generation. Although the signal decay was fast and the coefficient d33 was low, we found that increasing the power of the seeding beams could improve the second-harmonic signal decay process.

Three laser dyes (perylene orange, perylene red and pyrromethene 567) were dispersed in TEOS-, TEOS/GPTMS-, MTES- and VTES-gel glasses, respectively. The surroundings and fluorescence photostability of the dyes in gel glasses were studied. Due to the formation of a hydrogen bond between the dye and the residual Si–OH attached on the surface of the cages and pores, spectral red shifts of perylene orange at 10 K in TEOS- and TEOS/GPTMS-gel glasses with respect to that in MTES- and VTES-gel glasses were observed. Perylene dyes are more likely to trap in the cages of MTES- and VTES-gel glasses and show high-fluorescence photostability, while ionic and polar pyrromethene 567 tend to appear in the polar pores of gel glasses, which leave pyrromethene 567 vulnerable to photochemical reactions with singlet oxygen and low-fluorescence photostability.

The precise and real-time monitoring of localized pH changes is of great importance in many engineering and environmental fields, especially for monitoring small pH changes in biological environments and living cells. Metal–organic frameworks (MOFs) with their nanoscale processability show very promising applications in bioimaging and biomonitoring, but the fabrication of nanoscale MOFs is still a challenge. In this study, we synthesized a nanoscale mixed-lanthanide metal–organic framework by a microemulsion method. The morphology and size of the NMOF can be simply adjusted by the addition of different amounts of the CTAB surfactant. This NMOF exhibits significant pH-dependent luminescence emission, which can act as a self-referenced pH sensor based on two emissions of Tb3+ at 545 nm and Eu3+ at 618 nm in the pH range from 3.00 to 7.00. The MTT assay and optical microscopy assay demonstrate the low cytotoxicity and good biocompatibility of the nanosensor.

A near-infrared luminescent metal–organic framework Nd0.866Yb0.134BTB was developed as a self-calibrated thermometer in the physiological range. Its features include high sensitivity and resolution, and good biocompatibility, making such a material useful for biomedical applications.

A cationic robust Zr-cluster-based metal–organic framework has been developed for the efficient removal of Cr2O72− from aqueous solutions.

A lanthanide coordination polymer Tb0.957Eu0.043cpda was synthesized as a ratiometric and colorimetric luminescent thermometer. The high triplet excited state energy of a linker enables Tb0.957Eu0.043cpda to detect and visualize temperature over a wide range from cryogenic to room temperature (40–300 K).

A near infrared pumped luminescent metal–organic framework thermometer Nd0.577Yb0.423BDC-F4, with near infrared fluorescence and excellent sensitivity in the physiological temperature range (293–313 K), has been first realized, and might be potentially applied for biomedical systems.

A new metal–organic framework with –COOH groups has been realized and demonstrates strong interactions with methylene blue and thus the complete removal of methylene blue from aqueous solution.

A rare sty type microporous metal–organic framework, Cu2(FDDI) (ZJU-25; H4FDDI = tetramethyl 5,5′-(9H-fluorene-2,7-diyl)diisophthalate acid), was solvothermally synthesized and structurally characterized. With open metal sites and suitable pore space for their interactions with methane molecules, ZJU-25a exhibits absolute methane storage of 180 cm3(STP) cm−3 at room temperature and 35 bar, enabling it to be one of the very few porous MOFs whose methane storage capacities have met and/or approached the DOE target of 180 cm3(STP) cm−3 for material-based methane storage.

The first nanoscale luminescent metal–organic framework has been realized for the straightforward and highly sensitive sensing of nitroaromatic explosives in enthanol solution.

A doubly interpenetrated semiconducting MOF Zn4O(2,6-NDC)3(DMF)1.5(H2O)0.5·4DMF·7.5H2O (UTSA-38) of a cubic net has been constructed, which exhibits photocatalytic activity for the degradation of methyl orange in aqueous solution.

A luminescent metal–organic framework with small micropores for the enhanced recognition of Cu2+ exhibits highly sensitive and selective sensing of Cu2+ in aqueous solution.

Two series of cationic dyes, named DM-n and DP-n, were encapsulated in three anionic isostructural MOFs with a 1D channel. Ordered arrangement of the dyes in the channel was investigated by using the microscope polarized absorption spectra of different dye and MOF composites. Furthermore, the tunable second order nonlinear optical properties of these MOF⊃dye materials were observed.

A new fluorescence probe for distinguishing Zn2+ and Cd2+ is designed and synthesized. For the first time to our knowledge, this probe can recognize similar metal ions by coherently utilizing intramolecular charge transfer (ICT) and different electronic affinities of various metal ions, instead of by selective coordination alone, which may be interfered with and lose its selectivity easily in a complicated environment, providing a distinct recognition even by the naked eye for Zn2+ and Cd2+ with the sensitivity at the ppb level. This design strategy may initiate a straightforward approach for the selective detection of various metal ions with similar chemical properties in extensive applications such as environmental, industrial, and bio-science.

The reaction between polyoxometalate (POM) [TBA]12[WZn{Zn(H2O)}2(ZnW9O34)2] (TBA = tetrabutyl ammonium) and lanthanide (Ln) nitrate (Ln = La, Eu and Tb) in a mixed solvent of CH3CN and DMF yielded three noncentrosymmetric diamondoid Ln–POM solid materials, {[Ln2(DMF)8(H2O)6][ZnW12O40]}·4DMF (Ln–POM; Ln = La, Eu and Tb). In these compounds, the {ZnW12O40} unit, transferred from the metastable [WZn{Zn(H2O)}2(ZnW9O34)2] cluster, acts as a tetradentate ligand to connect with four Ln nodes, while the Ln ion links up two {ZnW12O40} units. These compounds generated interesting luminescence emissions that are dependent on the Ln ions and their ratios. White light emission was obtained by a doped approach with a rational ratio of the Eu3+ and Tb3+ ions.

The first luminescent two-dimensional MOF nanosheets NTU-9-NS Ti2(HDOBDC)2(H2DOBDC) (H2DOBDC = 2,5-dihydroxyterephthalic acid) fabricated via top-down delamination have been realized for the highly sensitive sensing of Fe3+ with a fast response. The highly dispersive nature and highly accessible active sites on the surface of the 2D NTU-9-NS nanosheets enable them to have close contact with targeted metal ions, which leads to the highly sensitive sensing of Fe3+ ions, with a fast response time within seconds and the best detection limit performance of 0.45 μM among MOF materials. The fast response and highly sensitive Fe3+ sensing based on the NTU-9-NS nanosheets sensor material highlights the promise of the two-dimensional MOF nanosheet approach for luminescent sensing applications. This work contributes to the development of research on two-dimensional MOF nanosheets materials with targeted and specific recognition for the application of biological and environmental luminescent sensors.

Three new six-branched chromophores with different isolation groups were designed and synthesized by incorporating azo chromophores onto phenyl glycerol ester via an esterification reaction. The chemical structures were confirmed by 1H NMR, 13C NMR, FT-IR spectroscopy, mass spectrometry, element analysis and UV-visible absorption spectra. The six-branched dendritic chromophores can form thin films directly without adding any polymer matrix and show a quite high chromophore loading density. After electric poling, the nonlinear optical coefficients (d33) of the dendrimer films were determined to be around 113, 142 and 136 pm V−1, which are almost 3 times the maximum d33 value of the azo-chromophore doped polymer films. The further improvement in optical nonlinearity was successfully realized by mixing the six-branched chromophores containing different isolation groups.

A microporous metal–organic framework MOF 1 [Zn(L)2(methanol)2] (H2L = (1R,3S)-1,2,2-trimethyl-3-(pyridin-4-ylcarbamoyl)cyclopentanecarboxylic acid) constructed from a flexible Zn2+ node and a flexible organic linker L was obtained by solvothermal reaction of diamond topology, and exhibits highly selective sorption of methanol over ethanol and water.

A new six-branched chromophore GGQ1 is designed and synthesized via the incorporation of an FTC-type chromophore 1 with phenyl glycerol ester. The six-branched chromophore GGQ1 shows a large molecular weight of 3834 Daltons and can directly form thin films with quite high active chromophore loading density. For comparison, guest–host doped polymer films are fabricated by doping chromophore 1 and BF1 into poly(4-vinylphenol). All of these doped films show a saturated trend in second harmonic generation coefficient (d33) and a maximum d33 value between 50–70 pm V−1 around the doping concentration of 25 wt%, due to the strong interchromophore electrostatic interactions. In contrast, GGQ1 films display a d33 value of 192 pm V−1. The results indicate that the six-branched chromophore could efficiently reduce the interchromophore electrostatic interactions and enhance the macroscopic optical nonlinearity, showing promise for applications in nonlinear optical (NLO) materials.

A highly stable amino-coordinated metal–organic framework ZJU-198 has been synthesized and structurally characterized, exhibiting high CO2 uptake of 105.8 cm3 cm−3 while blocking off N2 adsorption at 1.0 bar and 298 K, attributed to the unique pore window sizes.

Disposable and miniaturized organic photodiodes with spectral-resolving capabilities are fabricated based on polymeric conductive films doped with cyanine dyes by a drop-on-demand (DoD) inkjet method. The sensitivity and spectral resolution of the photodiodes at the J-aggregate absorption peaks of the corresponding cyanine dyes are improved by at least 800 times after the sequential in situ stacking of inkjet printed functional layers and optimization of the architecture, including the layer thickness and J-aggregate formation. The photodiodes are integratable onto the flowcytometry chips with waveguide laser arrays, demonstrating a spectral-resolving capability of ∼0.1 nm.

A new three-dimensional cationic metal–organic framework Zn8O(EDDA)4(ad)4·(HEDDA)2·6DMF·27H2O (ZJU-48; H2EDDA = (E)-4,4′-(ethene-1,2-diyl)dibenzoic acid; ad = adenine) was solvothermally synthesized and structurally characterized. ZJU-48 features a three-dimensional structure with a cationic skeleton and has one-dimensional pores along the c axis of about 9.1 × 9.1 Å2. The activated ZJU-48a exhibits a BET surface area of 1450 m2 g−1. The structural features of the charged skeleton of ZJU-48a have enabled its stronger charge-induced interaction with C2 hydrocarbons than with C1 methane, resulting in highly selective gas sorption of C2 hydrocarbons over CH4 with the adsorption selectivity over 6 at 298 K. The separation feasibility has been further established by the simulated breakthrough and pulse chromatographic experiments, thus methane can be readily separated from their quaternary mixtures at room temperature.

To immobilize both open metal and Lewis basic pyridyl sites into a microporous metal–organic framework, Cu6(PDC)6·2.6H2O (UTSA-50) was solvothermally synthesized and characterized. The combination of open metal sites and Lewis basic pyridyl functional sites leads to a high acetylene adsorption enthalpy of 39.4 kJ mol−1. As a result, UTSA-50 is a very promising MOF material for the highly selective separation of C2H2/CH4 and C2H2/CO2 at room temperature with the highest C2H2/CH4 separation selectivity of 68 ever reported and moderately high acetylene uptake of 91 cm−1 g−1.

Porous anatase TiO2 has been prepared, for the first time, through the calcination of a metal–organic framework (MOF) precursor under an air atmosphere at 380 °C. The resulting TiO2 has shown moderate porosity with a BET surface area of 220 m2 g−1 attributed to the highly porous structure of the MIL-125(Ti) precursor. The porous anatase TiO2 was examined as a lithium-ion battery anode, exhibiting high capacity retention and good rate capability. The porous structure of anatase TiO2 enforces Li+ diffusion and helps to buffer the volumetric variation. It has shown reversible capacities of 166, 106 and 71 mA h g−1 at 1 C, 5 C and 10 C charge/discharge rates, respectively, after 500 cycles.

By calcination of MOF-74(Ni) under reducing environments, nanosized Ni particles (5–10 nm) in carbon matrices were obtained, which were converted into NiS through an in situ reaction. Featuring small particle sizes (∼50 nm), uniform distribution and porosity, C ⊃ NiS was preliminarily studied as lithium-ion cathode material, which has shown electrochemical performance superior to that of bare NiS.

A new three-dimensional microporous metal–organic framework, Cu2(MFDI) (ZJU-60, H4MFDI = 5,5′-(9,9-dimethyl-9H-fluorene-2,7-diyl)diisophthalic acid), was solvothermally synthesized. ZJU-60 features a three-dimensional structure with a rare sty-a type topology and has two different types of pore apertures. With open metal sites and suitable pore spaces, ZJU-60 can readily separate methane in nearly pure form from CO2 and C2-hydrocarbon quaternary gas mixtures at room temperature with high separation capacity and moderate selectivity. The separation feasibility has been further established by simulated breakthrough and pulse chromatographic experiments.

A new fluorescent probe, (E)-3-(3-(4-([2,2′:6′,2′′-terpyridin]-4′-yl)phenyl)acryloyl)-7-(diethylamino)-2H-chromen-2-one (ZC-F4), composed of coumarin as the fluorophore and terpyridine as the receptor was designed and synthesized. This probe showed good selectivity and sensitivity towards Zn2+ even at the ppb level with significant variation of emission wavelength (more than 100 nm shifts) after combination with Zn2+. One can observe that the emission colour changed from green to red. A Job's plot test suggested a 1:1 stoichiometry between ZC-F4 and Zn2+, and the theoretical calculation based on density functional theory has been carried out to gain an insight into the sensing mechanism. Furthermore, imaging of Zn2+ in cells was also performed to test its feasibility in biology. This fluorescence probe should be a promising candidate for applications in cell-imaging, environment protection, water treatment and safety inspection.

A microporous MOF [Zn4(OH)2(1,2,4-BTC)2] (1,2,4-BTC = Benzene-1,2,4-tricarboxylate) with two immobilized open metal Zn2+ sites was obtained by solvothermal reaction, which exhibits highly selective guest sorption and sensing of nitrobenzene.

A nanoscale MOF material NMOF 1 with controllable morphologies is realized whose morphology control has been simulated based on the BFDH method. The targeted NMOF 1 exhibits highly sensitive, selective and instant “turn-on” sensing of bacterial endospores.

A new microporous metal–organic framework, Cu2(PDDI) (ZJU-5; H4PDDI = 5,5′-(pyridine-2,5-diyl)diisophthalic acid), was solvothermally synthesized and structurally characterized. With open metal sites, Lewis basic pyridyl sites and suitable pore space, the acetylene uptake in ZJU-5a reaches the highest value of 290 cm3 g−1 at 273 K and 1 bar. Furthermore, ZJU-5a exhibits high absolute methane storage of 190 cm3 (STP) cm−3 at 35 bar and 224 cm3 (STP) cm−3 at 60 bar at room temperature.

Metal–organic frameworks (MOFs) hold great promise for developing various types of luminescent sensors due to their remarkable structural diversity and tunable luminescence properties. In the last few years, utilizing luminescent MOFs to explore temperature sensing has gained intense attention. In this feature article, after the general description of luminescence thermometry, we have summarized the recent progress made in luminescent MOF thermometers, with particular emphasis on the dual-emitting MOFs that effectively illustrate the self-referencing temperature measurement based on the intensity ratios of two separate transitions.

A novel NbO type microporous metal–organic framework Cu2L (ZJU-32; H4L = 5′-((3,5-dicarboxyphenyl)ethynyl)-[1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylic acid) constructed from an elaborately designed tetratopic ligand was solvothermally synthesized and structurally characterized. The activated ZJU-32a exhibits high permanent porosity with the Brunauer–Emmett–Teller (BET) surface area of 3831 m2 g−1 and the pore volume of 1.482 cm3 g−1, enabling it to be a promising material for both methane storage and carbon dioxide capture at room temperature.

A tetracarboxylic acid ligand containing a highly polarized benzothiadiazole moiety was designed and used to construct the luminescent porous MOF ZJU-21, which can efficiently absorb the luminescent dye 4-[p-(dimethylamino)styryl]-1-methylpyridinium (DMASM) into the pores as well as sensitize it, yielding a dual-emitting MOF⊃dye composite ZJU-21⊃DMASM. The emission color of the resulting composite can be modulated by controlling the amount of dyes, and the intensity ratio of the two emissions can be used as a ratiometric thermometric parameter for temperature measurement. ZJU-21⊃DMASM also exhibits excellent temperature-dependent photoluminescence properties in the physiological temperature range, which, as well as the temperature and sensitivity ranges, can be tuned by controlling the concentration of DMASM in the pores of the host framework. Moreover, the proposed scheme can be readily applied to other luminescent porous MOFs and organic dyes, thereby providing a new perspective for the design of MOF⊃dye ratiometric temperature sensors.

A MOF thermometer, Dycpia, utilizing thermally coupled energy levels (TCELs) has been realized. Based on two emissions originating from two TCELs, Dycpia enables self-referenced temperature sensing in the range from 298 to 473 K with a high resolution of 0.05 K.

We have realized a rational design strategy to construct isostructural Tb3+ and Eu3+ doped lanthanide metal–organic framework materials whose colors can be easily tuned by the different combination of the doped Tb3+ and Eu3+ concentrations, generating white light emitting materials.