Dynamic metal–organic frameworks (MOFs) that respond to external stimuli have recently attracted great attention. However, the subtle control of dynamic processes as well as the illustration of the underlying mechanism, which is crucial for the targeted construction and modulation purpose, is extremely challenging. Herein, we report the achievement of simultaneous kinetic and thermodynamic modulation of the structure transformation processes of a family of cobalt(II)–organic frameworks, through the rational combination of coligand replacement, solvent molecule substitution, and ligand-based solid solution strategies. On the basis of the systematic investigation of the structural transformation behaviors, the underlying response mechanism and principles for modulation were illustrated. It is expected that this work can provide valuable hints for the study and further development of dynamic materials.Keywords: dynamic materials; kinetic control; metal−organic frameworks; sensing; structure transformation; thermodynamic control;

Aiming at the targeted construction of coordination polymer luminophores, the engineering of host–guest architectures with charge transfer based emissions is performed by utilizing the interactions between the electron-deficient 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) and electron-rich polycyclic aromatic hydrocarbons (PAHs) motifs as acceptors and donors, respectively. Through guest modulation of a prototype coordination polymer [Cd(tpt)(1,4-pda)(H2O)2]·(tpt)·(H2O)2 (1) (1,4-H2pda = 1,4-phenylenediacetic acid), a series of coordination polymers with different PAHs as guests, [Cd2(tpt)2(1,4-pda)2]·guest (2–5) (guest = triphenylene for 2, pyrene for 3, coronene for 4, and perylene for 5), are successfully fabricated. Distinct from 1, coordination polymers 2–5 reveal unique bilayer structures with PAHs interlayer and good stability, owing to the enhanced stacking interactions between tpt motifs and PAH guests. Moreover, their emissions cover a wide range of wavelength due to the effective guest to host charge transfer interactions between donor and acceptor motifs. Their readily tunable host–guest charge transfer based emissions make them good candidates as potential luminophores.Keywords: charge transfer emissions; coordination polymer; directed assembly; host−guest engineering; luminophore;

A new two dimensional (2D) Eu3+ coordination polymer, named [Eu(BTB)(H2O)2·solvent]n (1) (H3BTB = 4,4′,4′′-benzene-1,3,5-triyl-tribenzoic acid) has been constructed and investigated for sensing properties. Complex 1 shows structural flexibility originating from the 2D layer architecture, which could be triggered by the removal/restore of coordinated and guest solvent molecules. Benefiting from the high stability and intensive Eu3+ based emission of 1, it could be used as an effective fluorescence sensor for acetone with remarkable anti-interference and recyclability. In addition, the impact of structural features on the sensing performance of the complex was investigated, and enhanced sensing sensitivity was achieved with the desolvated complex.

By inserting a ligand into a reported metal–organic framework (Co-MOF1), the reformed aggregation of triangle grids (Co-MOF1-tpt) shows enhanced stability. In addition, owing to its structural characteristic, the Co-MOF1-tpt also reveals a certain CO2 storage ability and CO2/CH4 adsorption selectivity as expected.

Two GdIII coordination polymers with the formula [Gd(cit)(H2O)]∞ (1) and [Gd(nta)(H2O)2]∞ (2) (H4cit = citric acid, H3nta = nitrilotriacetic acid) have been successfully prepared under hydrothermal conditions. Complex 1 exhibits a three-dimensional (3D) structure based on carboxylate-bridged layers, while complex 2 is a double-layer structure containing eight-coordinated GdIII. Magnetic investigations reveal that weak antiferromagnetic couplings between adjacent GdIII ions in both 1 and 2 with different Weiss values result in large cryogenic magnetocaloric effects. It is notable that the maximum entropy changes (−ΔSmaxm) of 1 and 2 reach 31.3 J kg−1 K−1 and 32.2 J kg−1 K−1 at 2 K for a moderate field change (ΔH = 3 T), and a remarkable −ΔSmaxm (41.5 J kg−1 K−1 for 1 and 42.0 J kg−1 K−1 for 2) could be obtained for ΔH = 7 T.

The assembly of distinct 3d metal ions with triangular 1,3,5-benzenetricarboxylic acid (H3BTC) generates three new metal–organic frameworks, namely {[Co3Na(BTC)2(μ3-OH)(H2O)3(DMAc)]·H2O·0.5DMAc}n (1), {[Ni3(BTC)2(μ3-OH)(H2O)3]·2H2O·DMAc}n (2) and {[NH2(CH3)2]2[Mn3(BTC)2(CH3COO)2]·DMAc}n (3) (DMAc = N,N′-dimethylacetamide). Complexes 1 and 2 show Co3/Ni3 cluster based three-dimensional (3D) frameworks with (3,7)-connected new topology and (3,6)-connected sit topology, respectively, while complex 3 reveals a 3D framework composed of one-dimensional rod-shaped sinusoidal-like MnII-chains. Magnetic investigation shows that 1–3 display antiferromagnetic behaviors although they feature different spin carriers and linkage modes of spin carriers.

Originated from the pore space segmentation modification of a reported metal–organic framework (MOF) (NOTT-125), a new porous MOF ZnX was obtained and characterized by single-crystal X-ray diffraction, elemental analysis, X-ray powder diffraction and TGA. The ZnX exhibits remarkable selective CO2 adsorption property compared with that of the NOTT-125, which should be attributed to the enhanced gas-framework interactions induced by the fragmented pore space in ZnX.基于对一例已报道的金属-有机框架材料(NOTT-125)的孔道空间分割修饰,本文获得了一例新的多孔金属有机框架ZnX,并利用单晶X射线衍射,元素分析,X射线粉末衍射和热重对其进行了表征研究。性质研究表明,孔道分割修饰增强了ZnX中气体与框架间的相互作用,使得其相比于NOTT-125展现出更好的CO2选择性吸附性质。

A novel “cage-in-cage” metal–organic framework based on nested cages originated from two-fold interpenetrated networks was reported, which indicates the potential of interpenetration in structure modulation of cage-based MOFs.

A triphenylene-based conjugated microporous polymer (TP-CMP) has been synthesized and shows high surface area (SBET = 1104 m2 g−1) and remarkable uptakes of H2 (7.08 mmol g−1 at 77 K and 900 mmHg) and CO2 (3.37 mmol g−1 at 273 K and 900 mmHg). In addition, it could be utilized to detect nitrobenzene selectively via fluorescence quenching.

A new three-dimensional porous metal–organic framework, {[NH2(CH3)2][Zn(atz)(ox)]·H2O}n (1) (Hatz = 5-amino-1H-tetrazole, H2ox = oxalic acid), has been solvothermally synthesized and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction analysis. Complex 1 exhibits an anionic framework that can be simplified as a rarely reported 4-connected lon network. Complex 1 could be utilized as a platform for emission tuning by doping different lanthanide ions. In addition, gas adsorption studies reveal that 1 has a high isosteric heat of CO2 and good adsorption selectivity for CO2 over CH4 and N2.

A 3D metal–organic framework, [NH2(CH3)2]2[Cd17(L)12(μ3-H2O)4(DMF)2(H2O)2]·solvent (1), has been constructed with a π-electron rich aromatic ligand 2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene (H3L) and d10 configuration metal ion Cd2+ under solvothermal conditions. The crystal structure reveals that complex 1 consists of hexanuclear and trinuclear cadmium building units, which are further bridged by the multicarboxylate ligands to give a (3, 6, 12)-connected topological net. This complex exhibits strong ligand originated photoluminescence emission, which is selectively sensitive to electron-deficient nitroaromatic explosives (nitrobenzene, 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene). This property makes complex 1 a potential fluorescence sensor for these chemicals.

Two luminescent coordination polymers were constructed with a fluorescent ligand. The emissions of these compounds could be effectively and selectively quenched by acetone, showing their potential as acetone sensors. The formation of a coordination polymer structure is proven to be responsible for their strong emission and sensing properties.

With a flexible aromatic ligand, bis-(3,5-dicarboxy-phenyl)terephthalamide (H4L), two metal–organic frameworks, Cd(L)·(HDMA)2(DMF)(H2O)3 (1) and Zn(L)·(HDMA)2(DMF)(H2O)6 (2), were synthesized using a solvothermal method. Both 1 and 2 possess a 3D open framework. These two compounds exhibit strong photoluminescence in suspensions, and their luminescence could be efficiently and selectively quenched by a series of nitroaromatics. Thus, 1 and 2 could be used as excellent luminescent probes for nitroaromatic explosives. Additionally, 1 and 2 could also be utilized as the sensing platforms for DNA strands, which is attributed to their different affinities for single- and double-stranded DNAs. With this method, 0.05 nM of target DNA could be detected, and the selectivity could be down to a single nucleotide mismatch. This work shows the potential of MOFs for the sensing of versatile chemicals.

Two new zinc MOFs with similar “pillar-layered” framework structures based on 1,1′-biphenyl-2,2′,6,6′-tetracarboxylic acid (H4bpta) and two different bipyridine pillar ligands, namely {[Zn4(bpta)2(4-pna)2(H2O)2]·4DMF·3H2O}n (1) and {[Zn2(bpta)(bpy-ea)(H2O)]·2DMF·H2O}n (2) (4-pna = N-(4-pyridyl)isonicotinamide and bpy-ea = 1,2-bis(4-pyridyl)ethane), have been synthesized and investigated with their CO2 adsorption properties. By analysis of the structure properties and the CO2 adsorption performances of these two MOFs, it was found that the introduction of polar acylamide groups via 4-pna resulted in 1 with enhanced CO2 capacity and CO2/CH4 selectivity at low pressure. In contrast, the framework of 2 shows flexible properties originating from the flexibility of the ethanediylidene group in the bpy-ea ligand, which benefits the sieve effect of pores to give higher CO2/CH4 selectivity at a relatively high pressure range.

Two new porous coordination polymers (PCPs) based on different nanosized C3 symmetry ligands and Zn(II)-benzotriazolate clusters have been synthesized solvothermally. Both of the desolvated complexes show selective uptake of CO2 over CH4 and N2 at ambient temperature.

A series of porous pillar-layer frameworks have been prepared with 1,3,5-tris(p-imidazolylphenyl)benzene (tipb) as the main ligand and dicarboxylic acids as coligands. Our studies have demonstrated that tipb is prone to form a 63 layer with targeted metal ions, which could be utilized to construct pillar-layer frameworks. The structure and porous properties of the resulting metal–organic frameworks could be tuned by modifying the size, geometry, and functional groups of the coligands (pillars). Moreover, gas adsorption measurements revealed that both complexes 1 and 2 exhibit selective adsorption of H2 over N2 for the pore-size effect.

One Fe6 wheel and two Fe10 clusters were obtained with a step-by-step strategy. The wheel and cluster complexes were synthesized by reacting Fe3O precursors with triethanolamine. A magnetic investigation indicates that the Fe6 wheel shows strong antiferromagnetic behavior.

In this work, three polyimides (PIs) are successfully synthesized by the condensation reaction of an aromatic triamine with three difunctional aromatic dianhydrides. These materials show electrochemical lithium ion storage properties as cathodes for lithium-ion batteries. The aromatic dianhydride monomers are found to have significant effects on their performances. In addition, the polymer PI-1 shows narrow micropore size distributions and selective adsorption of CO2 over CH4 and N2. Furthermore, PI-1 exhibits a high Qst value (11.7 kJ mol−1) for H2 adsorption.

•One Co-based MOF prepared by O-donor bridging and N-donor chelating mixed-ligands•The MOF constructed by infinite sinusoidal-like rod-shaped Co–{Co3}-chains as SBUs•The MOF displays canted antiferromagnetic behavior.A novel Co-based metal–organic framework {[Co4(1,3-bdc)3(bta)2(CH3CH2OH)2]·CH3OH·H2O}n (1) (H2bdc = 1,3-benzenedicarboxylate, Hbta = benzotriazolate), has been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction analysis. Compound 1 represents a new structural topology constructed by infinite sinusoidal-like rod-shaped Co–{Co3}-chains as secondary building units. Moreover, the magnetic properties of 1 have been well investigated.A novel Co-based MOF has been synthesized and characterized by various state-of-the-art methods. The MOF represents a new structural topology constructed by infinite sinusoidal-like rod-shaped Co–{Co3}-chains as SBUs. Moreover, the MOF 1 displays canted antiferromagnetic behavior.

•Two unique complexes based on Mg(II) ions and flexible carboxylate ligands have been synthesized and investigated.•Two analogue ligands were investigated to clarify the effect of the flexible arms on the structure of the complexes.•Complex 1 exhibits extensive solid photoluminescence emission and a high adsorption heat (Qst) for CO2.Two new Mg(II)-based coordination polymers, {[Mg3(tci)2(DMAC)4]·2DMF}n (1) and [Mg(bci)(H2O)2]n (2) (H3tci = tris(2-carboxyethyl) isocyanurate, H2bci = bis(2-carboxyethyl) isocyanurate, DMAC = N,N′-dimethylacetamide, DMF = N,N′-dimethylformamide), were synthesized by using two similar flexible ligands with different number of arms, and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis, X-ray powder diffraction and TGA. Complexes 1 and 2 exhibit a structure progression from a rare two-dimensional (2D) kgd sheet to a three-dimensional pillar-layer structure involving the layer of Mg(II)–carboxylate connected by bci2 − ligands. The structure dissimilarity between them was dependent on the different number of arms of the two ligands. In addition, the solid state luminescent property and CO2 adsorption of complex 1 were also investigated.Two Mg(II) coordination polymers with different dimensions have been successfully synthesized by selecting the ligands with different number of arms. Complex 1 is a two-dimensional layer which can be represented as a (3,6)-connected 2-nodal net with a kgd topology, while complex 2 exhibits a three-dimensional pillar-layer structure. In addition, complex 1 exhibits extensive solid photoluminescence emission and a high adsorption heat (Qst) for CO2.

•A sensor (1) with quadrapyridyl type receptor and large chromophore was obtained.•1 exhibit sensitive off-on fluorescent response to Cd2+ in aqueous media.•The response of 1 to Cd2+ is immune to the interference of other metal cations.•1 is highly biocompatible and was used to the in vivo Cd2+ imaging in living cells.By retaining the quadrapyridyl receptor of polypyridylhexaazatriphenylene (a Cd2+ sensor reported by us) and extending its chromophoric group with pyrene, a chemical sensor (1) was designed and synthesized in this work. This sensor exhibit selective off-on fluorescence response to Cd2+ over other metal ions, and the detection limit is as low as 0.02 μM. The Cd2+ sensing of 1 has high water toleration and can be carried out in the media with the water content up to 70%. Additionally, 1 was successfully applied to the in vivo imaging of intracellular Cd2+ in living HaLa cells, and showed low cytotoxicity and cell membrane permeability in these experiments. These results suggest that 1 has potential application in the Cd2+ analysis of environmental and biological samples.A polypyridyl-pyrene based chemical sensor showed selective off-on fluorescence response to Cd2+ in aqueous media and was successfully applied to the in vivo imaging of Cd2+ in living cells.

Two complexes {[Mn3(btcit)2(H2O)2(DMF)2]·2DMF}∞ (1) and {[Mn3(btcit)2(bib)2]·2DMF}∞ (2) (H3btcit = 4,4′,4′′-[1,3,5-benzenetriyltris(carbonylimino)]trisbenzoic acid, bib = 1,4-bis(imidazol-1-yl)benzene) were obtained under the same reaction condition. Complex 1 is a two dimensional (4,4) network constructed from linear Mn3 units and btcit ligands. Complex 2, which presents an interesting two-fold interpenetrating three dimensional framework with fsf topology, was obtained by modifying complex 1 with a “pillaring” approach. Moreover, the magnetic properties of 1 and 2 have been investigated and both of them show antiferromagnetic behaviour.

The synthesis, characterization and ion binding properties of a new ditopic ratiometric receptor (1), based on 2-(4,5-dihydro-1H-imidazol-2-yl)phenol and crown ether moieties, have been described. The ditopic ratiometric receptor has been studied in sensing both F− and Zn2+ ions, exhibiting different fluorescent colour changes from cyan green to blue/black observable by the naked eye under UV-light. The addition of Zn2+ to the solution of 1 induced the formation of a 2:2 ligand–metal complex 1–Zn2+, which displays a remarkable blue shift of the emission maxima of 1 from 455 nm to 400 nm due to the inhibition of excited-state intramolecular proton transfer (ESIPT) mechanism. The sensing processes were monitored by fluorescence/absorption titrations, and further confirmed by Job's plot and 1H NMR titrations. The crystal structure of 1–Zn2+ reveals that 1 binds Zn2+ in four-coordinated modes. Furthermore, 1 is cell permeable and may be applied to detect trace Zn2+ and F− during the development of a living organism.

A luminescent two-dimensional (2D) coordination polymer is demonstrated to be a selective sensing material for the straightforward detection of nitrobenzene via a redox fluorescence quenching mechanism.

•A new Al3 + sensor has been synthesized and characterized.•It can serve as a selective ratiometric and colorimetric chemosensor for Al3 + based on internal charge transfer (ICT).•The sensor is effective in presence of other ions like Fe2 +, Zn2 +and Cu2 +.A new receptor based on a dibenzo-18-crown-6 derivative is successfully synthesized and characterized. This receptor reveals selective recognition toward Al3 + ion, along with colorimetric and fluorometric dual-signaling responses based on internal charge transfer (ICT). Also, it can serve as a highly selective chemodosimeter for Al3 + with naked-eye detection.A new chemosensor based on 18-crown-6 derivative has been synthesized and characterized, which could serve as a ratiometric and colorimetric sensor for Al3 + based on internal charge transfer (ICT).

A new metal–organic framework (MOF) based on metal clusters as secondary building units (SBU), has been synthesized and structurally characterized. The reported MOF presents an interesting 8-connected self-penetrating coordination network based on dinuclear cadmium cluster with a 424·5·63 topology. Moreover, the thermal stability and luminescence property of this compound have been investigated.A new metal–organic framework presents an interesting 8-connected self-penetrating coordination network based on dinuclear cadmium cluster with a 424·5·63 topology.

Two new compounds (1 and 2) based on indole were successfully synthesized and characterized. They display highly selective response to F− in aqueous DMSO medium and pure DMSO with remarkable color and fluorescent changes. Therefore, both receptors may serve as colorimetric sensors for F− by visual detection.Two new compounds 1 and 2 based on indole were successfully synthesized and characterized. They display an excellent selectivity toward the detection of F− in aqueous DMSO medium or pure DMSO with clear color changes and remarkable fluorescent changes based on photoinduced electron transfer (PET).

Originated from the pore space segmentation modification of a reported metal–organic framework (MOF) (NOTT-125), a new porous MOF ZnX was obtained and characterized by single-crystal X-ray diffraction, elemental analysis, X-ray powder diffraction and TGA. The ZnX exhibits remarkable selective CO2 adsorption property compared with that of the NOTT-125, which should be attributed to the enhanced gas-framework interactions induced by the fragmented pore space in ZnX.

A four-fold interpenetrated three dimensional (3D) metal–organic framework, [Cd2(tppe)(bpdc)2(H2O)]·solvent (1), was synthesized with a tetraphenylethene (TPE)-based ligand, 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethene (TPPE). This complex exhibits intense blue luminescence and is sensitive to toxic volatile organic compounds (VOCs).

With a flexible aromatic ligand, bis-(3,5-dicarboxy-phenyl)terephthalamide (H4L), two metal–organic frameworks, Cd(L)·(HDMA)2(DMF)(H2O)3 (1) and Zn(L)·(HDMA)2(DMF)(H2O)6 (2), were synthesized using a solvothermal method. Both 1 and 2 possess a 3D open framework. These two compounds exhibit strong photoluminescence in suspensions, and their luminescence could be efficiently and selectively quenched by a series of nitroaromatics. Thus, 1 and 2 could be used as excellent luminescent probes for nitroaromatic explosives. Additionally, 1 and 2 could also be utilized as the sensing platforms for DNA strands, which is attributed to their different affinities for single- and double-stranded DNAs. With this method, 0.05 nM of target DNA could be detected, and the selectivity could be down to a single nucleotide mismatch. This work shows the potential of MOFs for the sensing of versatile chemicals.

By inserting a ligand into a reported metal–organic framework (Co-MOF1), the reformed aggregation of triangle grids (Co-MOF1-tpt) shows enhanced stability. In addition, owing to its structural characteristic, the Co-MOF1-tpt also reveals a certain CO2 storage ability and CO2/CH4 adsorption selectivity as expected.

Two GdIII coordination polymers with the formula [Gd(cit)(H2O)]∞ (1) and [Gd(nta)(H2O)2]∞ (2) (H4cit = citric acid, H3nta = nitrilotriacetic acid) have been successfully prepared under hydrothermal conditions. Complex 1 exhibits a three-dimensional (3D) structure based on carboxylate-bridged layers, while complex 2 is a double-layer structure containing eight-coordinated GdIII. Magnetic investigations reveal that weak antiferromagnetic couplings between adjacent GdIII ions in both 1 and 2 with different Weiss values result in large cryogenic magnetocaloric effects. It is notable that the maximum entropy changes (−ΔSmaxm) of 1 and 2 reach 31.3 J kg−1 K−1 and 32.2 J kg−1 K−1 at 2 K for a moderate field change (ΔH = 3 T), and a remarkable −ΔSmaxm (41.5 J kg−1 K−1 for 1 and 42.0 J kg−1 K−1 for 2) could be obtained for ΔH = 7 T.

A luminescent two-dimensional (2D) coordination polymer is demonstrated to be a selective sensing material for the straightforward detection of nitrobenzene via a redox fluorescence quenching mechanism.

A 3D metal–organic framework, [NH2(CH3)2]2[Cd17(L)12(μ3-H2O)4(DMF)2(H2O)2]·solvent (1), has been constructed with a π-electron rich aromatic ligand 2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene (H3L) and d10 configuration metal ion Cd2+ under solvothermal conditions. The crystal structure reveals that complex 1 consists of hexanuclear and trinuclear cadmium building units, which are further bridged by the multicarboxylate ligands to give a (3, 6, 12)-connected topological net. This complex exhibits strong ligand originated photoluminescence emission, which is selectively sensitive to electron-deficient nitroaromatic explosives (nitrobenzene, 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene). This property makes complex 1 a potential fluorescence sensor for these chemicals.

Two luminescent coordination polymers were constructed with a fluorescent ligand. The emissions of these compounds could be effectively and selectively quenched by acetone, showing their potential as acetone sensors. The formation of a coordination polymer structure is proven to be responsible for their strong emission and sensing properties.