A series of electronically active viologen dications (RV) with tunable substituent groups were utilized to hybridize with [Ge4S10]4– (T2 cluster) to form the hybrids of T2@RV. These hybrids exhibited variable supermolecular assembly formation, tunable optical absorption properties, and different photoelectric response under the influence of different RV dications. Raman testing and time-dependent photocurrent response indicated that the photosensitivity and photostability of T2@RV could be integrated while choosing suitable RV dications. Current research provides a general method to build a tunable hybrid system based on crystalline metal chalcogenide compounds through the replacement of photoinactive cationic organic templates with photoactive ones with different substituent groups.

Developing the structural diversity of microporous zeolitic frameworks with integrated semiconducting properties is promising but remains a challenge. Reported here are two unique crystalline semiconductor zeolite analogues constructed from two kinds of indium selenide clusters with augmented ctn and zeolite-type sod networks. The intrinsic semiconducting nature in these In–Se domains gives rise to pore-size-dependent and visible-light-driven photocatalytic activity for organic dye degradation.

Reported here is a new open-framework metal chalcogenide containing extra-large 36-ring channels. This compound has a 3-connected etc topology by regarding supertetrahedral T2 clusters as the structural nodes. It has a very low framework density (3.4 tetrahedra per 1000 Å3) with each framework cation participating in three 3-rings. The organic cations within its intersecting channels can be partially exchanged out by Cs+ ions with the preservation of its framework structure.

•Two isostructrual compounds featuring a 1-D anionic chain of [Cu2MSe5]4- (M=Ge, Sn) displays photocurrent response in the visible light and near-IR range, respectively.•Compound 1–2 show a wide range of optical absorption covering visible and near-infrared range. Compared with 1 (M=Ge), crystalline sample of 2 (M=Sn) shows the red shift in the optical band gap.•Compound 2 displays a good photocurrent response when a three-electrode photoelectric cell coupled with 780 nm optical filter, which make it potential semiconductor sensor used in photoelectric devices.Reported here are two solvothermally synthesized metal selenides, namely [Cu2MSe5][Mn(H+-en)2(en)] (M = Ge (1) and Sn (2), and en=ethanediamine). The two isostructural compounds feature a 1-D anionic chain of [Cu2MSe5]4- with the existence of strong Cu∙∙∙Cu interaction. The estimated optical band gap was determined to be 1.69 eV for 1 and 1.49 eV for 2, indicating their semiconducting nature. Interestingly, 2 exhibits NIR-triggered photoelectric response, which make it potential semiconductor sensor used in photoelectric devices.Two isostructural compounds feature a 1-D anionic chain of [Cu2MSe5]4- (M=Ge, Sn) with the existence of strong Cu···Cu interaction. [Cu2GeSe5]·[Mn(H+-en)2(en)] displays a slight photocurrent under the irradiation of visible light, and [Cu2SnSe5]·[Mn(H+-en)2(en)] shows good photocurrent response in near-IR range.Download high-res image (220KB)Download full-size image

A new host–guest hybrid system with MnS clusters confined in a chalcogenide-based semiconductor zeolite was for the first time constructed and its photoluminescence (PL) properties were also investigated. The existence of MnS clusters in the nanopores of the semiconductor zeolite was revealed by UV-Vis absorption spectroscopy, steady-state fluorescence analysis, Raman as well as Fourier transform infrared (FTIR) spectroscopy. The aggregation state of the entrapped MnS clusters at different measurement temperatures was probed by electron paramagnetic resonance (EPR) spectroscopy. Of significant importance is the fact that the entrapped MnS clusters displayed dual emissions at 518 nm (2.39 eV) and 746 nm (1.66 eV), respectively, and the long-wavelength emission has never been observed in other MnS-confined host–guest systems. These two emission peaks displayed tunable PL intensity affected by the loading level and measurement temperature. This can be explained by the different morphologies of MnS clusters with different aggregation states at the corresponding loading level or measurement temperature. The current study opens a new avenue to construct inorganic chalcogenide cluster involved host–guest systems with a semiconductor zeolite as the host matrix.

We investigated the amine-induced structure transformation of four selenidostannates, i.e. [Sn3Se7Fe(TEPA)]n (1), {[Sn2Se6]·4(H+-PR)} (2), {[Sn2Se6]·2[Fe(en)3]} (3), and {[Sn3Se7]n·2n(H+-DBN)} (4) (TEPA = tetraethylenepentamine, PR = piperidine, en = ethylenediamine, DBN = 1,5-diazabicyclo[4.3.0]non-5-ene), which were characterized by single-crystal X-ray diffraction and UV-vis spectroscopy. The TEPA-induced 1D chain structure of [Sn3Se7Fe(TEPA)]n in 1 can undergo cleavage of Se–Fe and Se–Sn bonds to form a 0D dimer unit of [Sn2Se6]2− observed in 2 and 3, induced by PR and en, respectively. More interestingly, under the induction of en and DBN templates, such a 1D chain can counterintuitively fuse into a 2D layered structure of [Sn3Se7]n2n− through the removal of [Fe(TEPA)] species and reformation of Sn–Se bonds. Moreover, these selenidostannates with different structural dimensionalities display photocurrent responses, which make them hold some promise as a potential semiconducting material applied in photoelectric devices.

We demonstrated here the first case of a vertex–edge connection mode in a three-dimensional open-framework chalcogenide built from the largest known T5 cluster. Such connection relies on a tri-coordinated edge sulfur atom, which serves as the linkage to bridge two adjacent T5 clusters. The architecture of the resulting structure can be classified as the infinite order of super-supertetrahedral T5 clusters (T5, ∞).

We report four new copper-rich open-framework chalcogenides (COCs) with the formulas [Cu8Ge6Se19](C5H12N)6 (1a), [Cu8Sn6Se19](C6H12N2)4(H2O)13 (1b), [Cu16Ge12S36][Ni(en)3]4(en)xCl1.5 (1c), and [Cu7Ge4Se13](C6H21N4) (2). Single-crystal X-ray diffraction analyses suggest that all of these compounds with pcu-type topology are completely built on icosahedral clusters. Of particular interest, the connection units linking the icosahedral clusters in 1a–1c are pure dimeric units in three axial directions. Such a case is unprecedented among previously reported COCs and pushes up the length limit of the connection mode, thereby resulting in the largest solvent-accessible space in COCs. Compound 2 is built on an intriguing and unprecedented mixed-metal Cu7GeSe13 cluster. The copper-rich nature of these compounds gives rise to a narrow band gap in the near-infrared range, making them hold promise for photoelectric applications.

A deep understanding of distinct functional differences of various defects in semiconductor materials is conducive to effectively control and rationally tune defect-induced functionalities. However, such research goals remain a substantial challenge due to great difficulties in identifying the defect types and distinguishing their own roles, especially when various defects coexist in bulk or nanoscale material. Hereby, we subtly selected a molecular-type semiconductor material as structural mode composed of supertetrahedral chalcogenide Cd–In–S nanoclusters (NCs) with intrinsic vacancy point defect at the core site and antisite point defects at the surface of supertetrahedron and successfully established the correlation of those point defects with their own electrochemiluminescence (ECL) behaviors. The multichannel ECL properties were recorded, and the corresponding reaction mechanisms were also proposed. The predominant radiation recombination path of ECL emission peak at 585 nm was significantly distinguished from asymmetrically broad PL emission with a peak at 490 nm. In addition, the ECL performance of the coreless supertetrahedral chalcogenide nanocluster can be modulated by atomically precise doping of monomanganese ion at the core vacant site. A relatively high ECL efficiency of 2.1% was also gained. Actually, this is the first investigation of ECL behavior of semiconductor materials based on supertetrahedral chalcogenide nanocluster in aqueous solution. Current research may open up a new avenue to probe the roles of various different defects with defined composition and position in the NC. The versatile and bright ECL properties of Cd–In–S NC combined with tunable ECL potential and ECL peak suggest that the new kind of NC-based ECL material may hold great promising for its potential applications in electrochemical analysis, sensing, and imaging.

We demonstrated a unique copper-rich open-framework chalcogenide constructed from icosahedral Cu8Se13 and octahedral Cu4Se6 nanoclusters connected to each other through a SnSe3(Se2) bridging unit. The specific copper-rich composition gives rise to a narrow band gap and photoelectrical responsive properties in the infrared range.

Two cuprous iodide pseudopolymorphs, formulated as [(Cu4I4)(MBI)2]∞ (MBI = 1,1′-methylene-bis(imidazole)) with an irregular cubane-like Cu4I4 cluster as tetrahedrally coordinated secondary building unit and imidazole derivative as bridging ligand, have been synthesized and characterized by single-crystal X-ray diffraction analysis. Both of two compounds only exhibited a single broad low-energy cluster-centered (3CC) triplet emission band between room temperature and 77 K. Of particular interest, these two Cu4I4-imidazole pseudopolymorphs still displayed thermochromic luminescence originating from a red shift of such tunable single cluster-centered triplet emission, being different from that observed in the previously reported Cu4I4-pyridine system by balancing temperature-dependent multiple emissions (high-energy and low-energy) derived from their energetically distinct triplet states.

Luminescent lanthanide MOF materials are good sensors for analyzing some specific gas or volatile small molecules. However, some potential interference factors coming from the material itself, such as bridging ligands or guest solvent molecules entrapped in the channel of a MOF, were usually ignored during the sensing process. Here, two Tb:Eu-codoped indium-based MOFs with different bridging ligands were obtained for exploring the effects of ligand and guest solvent molecules on their luminescence properties. The current studies demonstrated that a ligand in the triplet state located between the excited states of Tb and Eu and polar guest solvent molecules encapsulated in the lanthanide MOF with such a type of ligand as the linker can interfere with the sensing process since they can substantially facilitate the energy transfer between Tb and Eu.

The safe use of nuclear energy requires the development of advanced adsorbent technology to address environment damage from nuclear waste or accidental release of radionuclides. Recently developed amine-directed chalcogenide frameworks have intrinsic advantages as ion-exchange materials to capture radionuclides, because their exceptionally negative framework charge can lead to high cation-uptake capacity and their 3-D multidimensional intersecting channel promotes rapid ion diffusion and offer a unique kinetic advantage. Prior to this work, however, such advantages could not be realized because organic cations in the as-synthesized materials are sluggish during ion exchange. Here we report an ingenious approach on the activation of amine-directed zeolitic chalcogenides through a stepwise ion-exchange strategy and their use in cesium adsorption. The activated porous chalcogenide exhibits highly enhanced cesium uptake compared to the pristine form and is comparable to the best metal chalcogenide sorbents so far. Further ion-exchange experiments in the presence of competing ions confirm the high selectivity for cesium ions. Excellent removal performance has also been observed in real water samples, highlighting the importance of stepwise ion exchange strategy to activate amine-directed chalcogenide framework for 137Cs+ removal.

Solid-state red phosphors of Mn2+-doped nanocrystals usually suffer from poor intensity. While the d–d emission of Mn2+ in yellow window has been extensively studied, shift toward lower energy remains challenging. Typically, intrinsic surface defects and self-purification of dopants are two obstacles for enhancing the intensity of red emission. Moreover, for red phosphors Mn2+ ions also need an appropriate host matrix and environment. Through an in situ doping strategy and optimization of the Mn2+ doping level, intense red-emitting Mn2+ dopant emission is reported here for MnCdInS@InS host. The doping strategy allows doping of Mn2+ at the core and/or surface sites of supertetrahedral “core–shell” nanocluster (Mn@MnCdInS@InS), leading to the red emission (at 643 nm) with over 40% quantum yield. Moreover, systematic control of doping level results in a series of crystalline Mn2+-doped materials with tunable photoluminescence quantum yield. In addition to the synthesis of an important class of red-emitting materials rarely obtained from Mn2+ doping, details of the physical chemistry associated with the doping process are probed with the new fundamental findings reported here.

We herein present the first case of energy transfer process in an inorganic chalcogenide-based semiconductor zeolite material (coded as RWY) serving as UV–vis light-harvesting host. A multistep vectorial energy transfer assay was fabricated by encapsulating acridine orange (AO) molecules into the RWY porous framework and further covering the formed capsules with rhodamine B (RhB) molecules. The UV high-energy excitations absorbed by RWY host were channeled to AO molecules and then onto RhB molecules to give rise to visible-light emission. The steady-state fluorescence and confocal microscope as well as fluorescent dynamics of emission reveal successfully the process of multistep vectorial energy transfer. This inorganic-host-involved energy transfer process has never been observed in an insulating oxide-based zeolite host system. Therefore, chalcogenide-based semiconductor zeolites could be a class of promising host materials to be further explored in the field of energy transfer and electron transfer between inorganic host and organic guest.

We report a new multi-step energy transfer process in a host–guest antenna system based on a chalcogenide semiconductor zeolite (coded as RWY). The multi-step vectorial energy transfer assay was fabricated by encapsulating both proflavine ions (PFH+) and pyronine ions (Py+) into the RWY porous framework, serving as a UV-vis light-harvesting host. The ultraviolet high-energy excitation absorbed by the RWY host was channeled to the PFH+ ions and then onto the Py+ ions to give rise to visible-light emission. The steady-state fluorescence and fluorescent dynamics of emission revealed successfully the process of multi-step vectorial energy transfer occurring in the RWY⊃(PFH+&Py+) host–guest antenna system. Moreover, the post treatment of guest ions, such as further acidification of the PFH+ ions and solvation of the guests, was also investigated to tune energy transfer efficiency in such host–guest antenna systems. The current study shows that deep protonation of PFH+ as well as solvation of guest ions can dramatically enhance energy transfer efficiency between the RWY host and PFH+, and even between PFH+ and Py+, much higher than that in an untreated host–guest antenna system.

We report a simple and yet effective method to introduce Mn2+ ions into semiconducting nanoclusters with atomically precise control. Our method utilizes one type of micrometer-sized crystals, composed of well-defined isolated supertetrahedral chalcogenide nanoclusters (∼2 nm, [Cd6In28S52(SH)4]) whose core metal site is unoccupied in as-synthesized pristine form. This unique model structure with vacant core site makes it possible to achieve ordered distribution of Mn2+ dopants, and at the same time effectively preclude the formation of Mn2+ clusters in the host matrix. A two-step synthesis strategy is applied to realize an atomically precise doping of Mn2+ ion into the core site of the nanoclusters, and to achieve uniform distribution of Mn2+ dopants in the crystal lattice. The PL, X-ray photoelectron (XPS), as well as the electron paramagnetic resonance (EPR) spectra reveal the successful incorporation of Mn2+ ion into the core site of the nanocluster. Different from the pristine host material with weak green emission (∼490 nm), the Mn2+-doped material shows a strong red emission (630 nm at room temperature and 654 nm at 30 K), which is significantly red-shifted relative to the orange emission (∼585 nm) observed in traditional Mn2+-doped II–VI semiconductors. Various experiments including extensive synthetic variations and PL dynamics have been performed to probe the mechanistic aspects of synthesis process and resultant unusual structural and PL properties. The quaternary semiconductor material reported here extends the emission window of Mn2+-doped II–VI semiconductor from yellow-orange to red, opening up new opportunities in applications involving photonic devices and bioimaging.

We apply a two-step strategy to realize ordered distribution of multiple components in one nanocluster (NC) with a crystallographically ordered core/shell structure. A coreless supertetrahedral chalcogenide Cd-In-S cluster is prepared, and then a copper ion is inserted at its void core site through a diffusion process to form a Cu-Cd-In-S quaternary NC. This intriguing molecular cluster with mono-copper core and Cd-In shell exhibits enhanced visible-light-responsive optical and photoelectric properties compared to the parent NC.

Chemically co-doping a micron-sized semiconductor single crystal while simultaneously segregating different dopant types uniformly on a nanoscale is synthetically challenging, but often essential for preventing unwanted dopant-related interference that may hamper optic and magnetic applications. Here by starting from a unique molecular crystal composed of well-defined discrete supertetrahedral chalcogenide nanoclusters (NCs), we successfully realized highly effective nanosegregation of dual dopants (Cu and Mn) in Cd–In–S semiconductor crystals. Our method takes advantage of the intrinsic single vacancy at the core of NC that permits the trapping of only one dopant ion. Such single-ion trapping effectively precludes two dopant ions from residing in the same NC, allowing us to target single-crystal white-light emitter by eliminating possible interference between dopants. This new method for controlling the distribution of multiple dopants on a nanoscale provides a promising route to modify and tune optical and magnetic properties of large-sized semiconductor single crystals for use in integrated multifunctional devices.

We report four new copper-rich open-framework chalcogenides (COCs) with the formulas [Cu8Ge6Se19](C5H12N)6 (1a), [Cu8Sn6Se19](C6H12N2)4(H2O)13 (1b), [Cu16Ge12S36][Ni(en)3]4(en)xCl1.5 (1c), and [Cu7Ge4Se13](C6H21N4) (2). Single-crystal X-ray diffraction analyses suggest that all of these compounds with pcu-type topology are completely built on icosahedral clusters. Of particular interest, the connection units linking the icosahedral clusters in 1a–1c are pure dimeric units in three axial directions. Such a case is unprecedented among previously reported COCs and pushes up the length limit of the connection mode, thereby resulting in the largest solvent-accessible space in COCs. Compound 2 is built on an intriguing and unprecedented mixed-metal Cu7GeSe13 cluster. The copper-rich nature of these compounds gives rise to a narrow band gap in the near-infrared range, making them hold promise for photoelectric applications.

Luminescent lanthanide MOF materials are good sensors for analyzing some specific gas or volatile small molecules. However, some potential interference factors coming from the material itself, such as bridging ligands or guest solvent molecules entrapped in the channel of a MOF, were usually ignored during the sensing process. Here, two Tb:Eu-codoped indium-based MOFs with different bridging ligands were obtained for exploring the effects of ligand and guest solvent molecules on their luminescence properties. The current studies demonstrated that a ligand in the triplet state located between the excited states of Tb and Eu and polar guest solvent molecules encapsulated in the lanthanide MOF with such a type of ligand as the linker can interfere with the sensing process since they can substantially facilitate the energy transfer between Tb and Eu.

We report a new multi-step energy transfer process in a host–guest antenna system based on a chalcogenide semiconductor zeolite (coded as RWY). The multi-step vectorial energy transfer assay was fabricated by encapsulating both proflavine ions (PFH+) and pyronine ions (Py+) into the RWY porous framework, serving as a UV-vis light-harvesting host. The ultraviolet high-energy excitation absorbed by the RWY host was channeled to the PFH+ ions and then onto the Py+ ions to give rise to visible-light emission. The steady-state fluorescence and fluorescent dynamics of emission revealed successfully the process of multi-step vectorial energy transfer occurring in the RWY⊃(PFH+&Py+) host–guest antenna system. Moreover, the post treatment of guest ions, such as further acidification of the PFH+ ions and solvation of the guests, was also investigated to tune energy transfer efficiency in such host–guest antenna systems. The current study shows that deep protonation of PFH+ as well as solvation of guest ions can dramatically enhance energy transfer efficiency between the RWY host and PFH+, and even between PFH+ and Py+, much higher than that in an untreated host–guest antenna system.

We demonstrated a unique copper-rich open-framework chalcogenide constructed from icosahedral Cu8Se13 and octahedral Cu4Se6 nanoclusters connected to each other through a SnSe3(Se2) bridging unit. The specific copper-rich composition gives rise to a narrow band gap and photoelectrical responsive properties in the infrared range.

We investigated the amine-induced structure transformation of four selenidostannates, i.e. [Sn3Se7Fe(TEPA)]n (1), {[Sn2Se6]·4(H+-PR)} (2), {[Sn2Se6]·2[Fe(en)3]} (3), and {[Sn3Se7]n·2n(H+-DBN)} (4) (TEPA = tetraethylenepentamine, PR = piperidine, en = ethylenediamine, DBN = 1,5-diazabicyclo[4.3.0]non-5-ene), which were characterized by single-crystal X-ray diffraction and UV-vis spectroscopy. The TEPA-induced 1D chain structure of [Sn3Se7Fe(TEPA)]n in 1 can undergo cleavage of Se–Fe and Se–Sn bonds to form a 0D dimer unit of [Sn2Se6]2− observed in 2 and 3, induced by PR and en, respectively. More interestingly, under the induction of en and DBN templates, such a 1D chain can counterintuitively fuse into a 2D layered structure of [Sn3Se7]n2n− through the removal of [Fe(TEPA)] species and reformation of Sn–Se bonds. Moreover, these selenidostannates with different structural dimensionalities display photocurrent responses, which make them hold some promise as a potential semiconducting material applied in photoelectric devices.

A new host–guest hybrid system with MnS clusters confined in a chalcogenide-based semiconductor zeolite was for the first time constructed and its photoluminescence (PL) properties were also investigated. The existence of MnS clusters in the nanopores of the semiconductor zeolite was revealed by UV-Vis absorption spectroscopy, steady-state fluorescence analysis, Raman as well as Fourier transform infrared (FTIR) spectroscopy. The aggregation state of the entrapped MnS clusters at different measurement temperatures was probed by electron paramagnetic resonance (EPR) spectroscopy. Of significant importance is the fact that the entrapped MnS clusters displayed dual emissions at 518 nm (2.39 eV) and 746 nm (1.66 eV), respectively, and the long-wavelength emission has never been observed in other MnS-confined host–guest systems. These two emission peaks displayed tunable PL intensity affected by the loading level and measurement temperature. This can be explained by the different morphologies of MnS clusters with different aggregation states at the corresponding loading level or measurement temperature. The current study opens a new avenue to construct inorganic chalcogenide cluster involved host–guest systems with a semiconductor zeolite as the host matrix.

Mn2+-Doped semiconductor nanocrystals or quantum dots have been extensively studied as potential yellow/orange/red phosphors due to the stable Mn2+-related emission tuned by its tetrahedral coordination environment in host lattices. However, it is still very difficult to objectively explore the location–performance relationship in conventional Mn2+-doped nanomaterials since the precise location information on Mn2+ dopants is generally unavailable due to their random distribution in host lattices. Herein, we purposely selected a specific supertetrahedral-nanocluster-based molecular crystal (OCF-40-ZnGaSnS, composed of isolated supertetrahedral T4-ZnGaSnS nanoclusters (NCs) with the formula [Zn4Ga14Sn2S35]12−) as a host lattice, and effectively controlled the relatively precise position of Mn2+ dopants in host lattices of T4-ZnGaSnS NCs by in situ substitution of Zn2+ sites by Mn2+ ions, and investigated the Mn2+-location-dependent red emission properties. The current study clearly indicates that a long-lifetime (∼170 μs) red emission centred at 625 nm at room temperature for lightly-doped [Zn3MnGa14Sn2S35]12− NCs with one Mn2+ dopant in its surface centre is very sensitive to temperature and dramatically red-shifts to 645 nm at 33 K upon the excitation of 474 nm. However, heavily-doped OCF-40-MnGaSnS (composed of T4-MnGaSnS NCs with the formula [Mn4Ga14Sn2S35]12−, in which four Mn2+ dopants are accurately located at its core in the form of Mn4S) gives the temperature-insensitive red emission with a longer wavelength (641 nm) and a shorter lifetime (42 μs) at room temperature. This phenomenon is pretty uncommon compared to other heavily Mn2+-doped semiconductors. Such differences in their PL properties are ascribed to Mn2+-location-induced lattice strain to different degrees in two Mn2+-doped supertetrahedral NCs. In addition, the Mn2+-related red emission of both samples can be predominantly induced by the direct excitation of Mn2+ ions and secondarily by indirect excitation through exciton energy transfer from host lattices to Mn2+ dopants. Consistently, the DFT calculations suggest that the emission of NCs originated from the transition from the low spin excited state of Mn2+ (4T1) to its high spin ground state (6A1). The calculation results also revealed that the emission wavelength of lightly-doped [Zn3MnGa14Sn2S35]12− NCs is not obviously affected by the temperature-induced thermal effect, but by temperature-induced structural contraction, while that of heavily-doped [Mn4Ga14Sn2S35]12− NCs is affected by both effects. The total temperature cooling effect on the emission of [Zn3MnGa14Sn2S35]12− NCs is the red-shift, while that on the emission of [Mn4Ga14Sn2S35]12− NCs is negligible, which is akin to the experimental results. This research opens up a new perspective and provides a feasible method to explore the location–performance relationship of other Mn2+-doped NCs.