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Sluggish charge transfer is the major problem which restricts the development of metal–organic framework (MOF)-based photocatalysts. Recently, facet-engineering has been proven to be an effective method for solving this issue. However, due to difficulties in regulating the exposed facets of MOFs, there are few reports about the facet-engineering of MOF-based photocatalysts. Here, we firstly report facet-engineering for promoting the photocatalytic activity of NH2-UiO-66 crystals. In this study, by regulating the influence of kinetics and thermodynamics, cubic, tetra-decahedral, and octahedral forms of NH2-UiO-66 are synthesized. The photocatalytic hydrogen evolution rate of tetra-decahedral NH2-UiO-66 with co-exposed (100) and (111) crystal facets reaches 64.06 μmol g−1 h−1, which is approximately 2 and 1.5 times greater than that of the cubic and octahedral forms of NH2-UiO-66, respectively. The density functional theory (DFT) calculation and ultrafast spectroscopy results indicate that a slight staggering exists in the band structure of (100) and (111) facets, causing the facets junction to appear. The facet junction promotes the charge separation efficiency and prolongs the lifetime of the charge carriers, thereby giving tetra-decahedral NH2-UiO-66 optimal photocatalytic performance. This study demonstrates the feasibility and potential of facet-engineering for photocatalytic applications of MOFs. [ABSTRACT FROM AUTHOR]

ZCS-C (ZnCdS/CdS) QDs were synthesized via low-temperature vulcanization using zeolitic imidazolate framework-8 (ZIF-8) nanoparticles as a precursor, cation exchange, and heterojunction construction. Without any precious metal as a cocatalyst, the photocatalytic hydrogen production rate of ZCS-C-3 QDs reached 2.7 mmol g−1 h−1 under visible light irradiation. The optimized sample exhibited an outstanding chemical stability and recyclability, which is superior to most of the reported Zn1−xCdxS-based photocatalysts. [ABSTRACT FROM AUTHOR]

Two luminescent coordination polymers (CPs), {[Cd2L2(H2O)4]·H2O}n (1) and {[Zn2L2(H2O)4]·H2O}n (2) (H2L = 5-(1H-1,2,4-triazol-1-yl)isophthalic acid) are reported herein. The CPs reveal readily dispersible two-dimensional (2D) layer structures with considerable stability in aqueous media within a wide pH range (pH = 2–12). Sensing experiments indicate that they can serve as highly selective and sensitive fluorescent probes toward CrVI-anions (CrO42− and Cr2O72−). [ABSTRACT FROM AUTHOR]

Three isostructural coordination polymers of the formula [MCl2(DMSO)2(pz)]n (pz = pyrazine, DMSO = dimethyl sulfoxide, M = Mn, Fe and Co for 1–3) were synthesized through the solvothermal reaction of MCl2, DMSO and pz. By introducing DMSO and chloride as electron donor ligands and pz as an accepter, a donor–metal–accepter (D–M–A) system was constructed. Radicals generated by photoinduced electron transfer (PET) from a donor to an accepter result in a dramatic change of vibronic absorption spectra in UV regions and remarkable enhancement of magnetic susceptibility. The mechanism of PET was also determined by PXRD, IR, EPR and XPS measurements. This is the first example of bridging pz complexes which exhibit both photochromism and photomagnetism in a PET process. [ABSTRACT FROM AUTHOR]

The construction of specific structures and heteroatom-doped nanomaterials is essential for enhancing the electrochemical performance of lithium-ion batteries (LIBs). Herein, three structures of cobalt nanoparticle embedded N,S-codoped carbon (CNSCo-x) nanocomposites are obtained by pyrolysis of different amounts of thioacetamide (TAA) sulfuretted zeolitic imidazolate frameworks (ZIF-67) under an Ar/H2 atmosphere. With the addition of 0.5 mmol of TAA, CNSCo-0.5 with an orderly and porous nanoplate structure is obtained. The CNSCo-0.5 exhibits the best rate behavior and cycling stability with an initial discharge capacity of 1355 mA h g−1 at 200 mA g−1, and high discharge capacities of 1360.4 mA h g−1 at the 200th cycle at 200 mA g−1, and 647.9 mA h·g−1 at the 400th cycle at 1000 mA g−1. This facile synthetic strategy could be extended to other MOFs and is significant for developing new materials for LIBs. [ABSTRACT FROM AUTHOR]

Developing high-performance electrode materials to replace a traditional graphite electrode is critical for the commercialization of lithium ion batteries, which however still remains a great challenge. Herein, we report a suitable method to synthesize a series of well-dispersed nanostructured Co3O4–CoFe2O4 composites (CCFs) from bimetallic metal–organic frameworks (BiMOFs) with varied Fe3+/Co2+ molar ratios. When used as anodes for lithium ion batteries, the CCF-12 composite exhibits a maximum initial discharge capacity of 1328 mA h g−1, a reversible capacity of 940 mA h g−1 at 100 mA g−1 after 80 cycles, and a better rate capability in comparison with those of pure Co3O4 and other CCF composites. The well-dispersed structure and small particle size are believed to mainly contribute to the outstanding electrochemical performance of CCF-12 electrodes. [ABSTRACT FROM AUTHOR]

By means of a mixed-ligand strategy, a novel bi-functional metal–organic framework, [H2N(CH3)2]·Zn(NDC)(atz)·H2O (NDC = 2,6-naphthalenedicarboxylic acid, Hatz = 1H-tetrazol-5-amine), was synthesized, which displays a three-dimensional two-fold interpenetrated framework. Owing to the introduction of two different functional organic ligands, this complex exhibits bi-functional properties, i.e., selective gas adsorption of CO2 over CH4 and fluorescence sensing response for nitrobenzene. [ABSTRACT FROM AUTHOR]

Based on the same in situ formed ligand, two new MOFs, namely {[Zn2(HL)2]·0.5DMF·H2O}n (1) and {[Cd2(HL)2]·1.5H2O}n (2) (H3L = 5-[(2H-tetrazol-5-yl)amino]isophthalic acid), have been solvothermally synthesized and structurally characterized by elemental analysis, IR, PXRD, and single-crystal X-ray diffraction. During the self-assembly process, the original ligand H2ATBDC (5-(5-amino-1H-tetrazol-1-yl)-1,3-benzenedicarboxylic acid) undergoes the Dimroth rearrangement to form a new ligand H3L, consequently contributing to the construction of the two new MOFs. Structural analysis reveals that both 1 and 2 possess a three-directional intersecting channel system and pts topology. The major structural difference between them is the metal coordination, which displays four- and six-coordinated modes in 1 and 2, respectively, and results in diverse channels and different stabilities. Moreover, the adsorption properties of 1a (i.e., the desolvated 1) have been studied, and the results show that 1a possesses moderate capability of gas sorption for N2, CO2, and CH4 gases, along with high selectivity ratios of 102 and 20 for CO2/N2 (15 : 85) and CO2/CH4 (50 : 50) at 273 K, respectively. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

A polydentate pyridyl derivative, 2,3,6,7,10,11-hexa(2-pyridyl)-dipyrazino [2,3-f:2′,3′-h]quinoxaline (HPDQ), exhibits a high-performance fluorescence response to La3+ with an ∼65 nm redshifted emission wavelength and 38 fold enhanced intensity, in contrast to its weakened emission for other lanthanide ions. The final La3+ coordination complex in solution has a stoichiometric ratio of 1 : 3 of ligand-to-metal, as testified by the Job's plot and single crystal structure analyses. The red shift of the luminescence emission as well as UV-vis absorption was rationalized in terms of the change of the electron structure as indicated by nuclear magnetic titration, electrochemical experiment and density functional theoretical calculation, while the significant enhancement of emission was attributed to the enhanced π conjugated extent of HPDQ caused by La3+ coordination. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work, the construction of Co3O4 two dimensional (2D) nano-assemblies utilizing infinite coordination polymers (ICPs) as precursors was investigated, aiming at the morphology targeted fabrication and utilization of 2D materials. Based on the successful modulation of morphology, a rose-like Co based ICP precursor was obtained, which was further transformed into porous Co3O4 nanoflake assemblies with a well-preserved 2D morphology and a large surface area. The mechanism of the morphology modulation was illustrated by systematic investigation, which demonstrated the crucial role of a modulating agent in the formation of 2D nano-assemblies. In addition, the cobalt oxide 2D nano-assemblies are fabricated into a lithium anode combined with graphene, and the remarkable capacity and stability (900 mA h g−1 after 50 cycles) of the resulting Co3O4/G nanocomposite indicates its potential in lithium battery applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Low-temperature hydrothermal reactions of copper salts with NaN3 and structurally related pyridine-based ligands, 1-(4-pyridyl)pyridinium, 3-chloromethylpyridine, 4-benzylpyridine, and quinoline (L4), respectively, led to the formation of four new magnetic complexes, [Cu3(L1)2(N3)6]n (1), [Cu3(L2)2(N3)6]n (2), [Cu(L3)2(N3)2] (3), and [Cu(L4)(N3)2]n (4). In these complexes, L1, L2, and L3 are pyridine, 3-azidomethylpyridine, and 4-benzoylpyridine, being generated in situ by the decomposition, azido substitution, and oxidation reaction of the 1-(4-pyridyl)pyridinium, 3-chloromethylpyridine, and 4-benzylpyridine, respectively. 1 and 2 have similar structures being composed of double end-on azido-bridging planar [Cu3(L)2(N3)6] trinuclear units, which are further linked into a two-dimensional layer by the end-to-end azido bridges of themselves, along with their weak end-on coordination. It is interesting that the only slight differences of geometrical parameters in 1 and 2 have led to distinct magnetic interactions between the trinuclear units, where the former is antiferromagnetic but the latter is ferromagnetic, whereas 3 has a mono-nuclear core structure, which is further extended to a one-dimensional (1D) chain by weakly coordinated end-on azido bridges. 4 consists of unique 1D chains with double end-on azido bridge bonding distorted five-coordinated Cu(ii) centers, and exhibits ferromagnetic intrachain interactions. In the structures of these complexes there also exist weak inter-layer or inter-chain hydrogen bonds, which should also be responsible for some magnetic behavior at low temperature. In addition, primary structural and magnetic comparisons and discussions have also been performed by combining other reported azido-Cu(ii) systems with related pyridyl-based co-ligands. These results show that the selection of synthesis conditions and slight decoration of co-ligands (or geometric differences of them) have important influences on the structures and magnetic properties of resulting metal azido complexes. [ABSTRACT FROM AUTHOR]

A new luminescent lanthanide metal–organic framework was synthesized under hydrothermal conditions by introducing the tetracarboxylic acid ligand (H4bptc) as a chromophore to sensitize the luminescence of the Tb3+ ion. Interestingly, despite the achiral nature of H4bptc, the resulting framework exhibited rare chiral helical channels. The luminescence studies revealed that this material showed a highly selective fluorescence quenching response to Fe3+ ions in liquid suspension, which can be conveniently observed by the naked eye under UV light. Thus, this material can be potentially used as a chemosensor for sensing Fe3+ ions and its selective luminescence quenching response can be explained in terms of the competitive absorption mechanism. [ABSTRACT FROM AUTHOR]

Upon solvothermal reactions between Cd(ii) salt and 5-pyridyl-tetrazolate (4-Ptz) under different reaction conditions, three new Cd(ii) metal–organic frameworks (MOFs), namely [Cd3(4-Ptz)5(H2O)2(μ3-OH)·3DMA·5H2O·CH3OH]n (1), [Cd5(4-Ptz)8(CH3OH)2(μ3-OH)2·2DMA·4H2O·3CH3OH]n (2) and [{Cd9(4-Ptz)14(AC)2(μ3-OH)2(H2O)4}·8DMA·H2O·3CH3OH]n (3), were synthesized based on different highly connected secondary building units (SBUs). In the presence of triethylamine, 1 was constructed based on an 8-connected triangular trinuclear Cd3 SBU and exhibits a three-dimensional framework, while 2 was generated upon the addition of HCl, assembled through a close packing of the octahedron cages consisting of unprecedented 12-connected 4-Ptz bridged Cd5 SBUs and thus showing high thermal and chemical stability. For generating 3, two different kinds of Cd3 SBUs, including an 8-connected triangular SBU and a 10-connected linear SBU, were constructed and further integrated into a distorted octahedron-based net under the addition of both triethylamine and NaCl. In addition to the structural analysis, we also focused on the investigation of gas adsorption and solid-state fluorescence properties of 2. [ABSTRACT FROM AUTHOR]

A new lanthanide metal–organic framework was constructed using a tripodal flexible zwitterion ligand (H3LBr3) which takes a chair-shaped configuration. The luminescence of the compound displays highly selective sensing of the Fe3+ ion and nitrobenzene. [ABSTRACT FROM AUTHOR]

The structure and magnetism of three cobalt(ii)–azide complexes, [Co(N3)2(bepy)2]n (1), [Co2(N3)4(vipy)4]n (2), and [Co(N3)2(bipy)]n (3) were tuned by three structurally related 4-substituent pyridines, 4-benzylpyridine (bepy), 4-vinyl pyridine (vipy), and 4,4′-bipyridine (bipy) as co-ligands in solvothermal reactions. With flexible benzyl as a substituent group of the pyridine co-ligand, a one-dimensional (1D) complex 1 with double end-to-end (EE) azide-bridging Co(ii) chain is formed. While using a rigid but small vinyl group as the substituent, a distinct Co(ii)–azide chain with alternate double end-on (EO) and double EE azide bridges was obtained. Finally, when another pyridine group was used instead of the substituent incapable of coordinating in 1 and 2, a bipyridine, it gave rise to a chiral complex 3 with a three-dimensional (3D) diamondoid Co(ii)–azide framework further reinforced by the bipy ligand. Magnetic studies indicate antiferromagnetic interactions between the Co(ii) ions in the three complexes, but interestingly, weak antiferromagnetism origin of spin canting exists in 3 at low temperatures. [ABSTRACT FROM AUTHOR]

Two MII tetranuclear complexes bridged only by azido, Mn4(N3)7.3Cl0.7L4 (1) and Co4(N3)8L4 (2) in which the four MII ions are precisely coplanar bridged only by six azido anions, were obtained by using 4,5-diazafluoren-9-one (L) as a corner ligand. Magnetic studies indicate that ferromagnetic coupling was conducted by the azido anions between MII ions. At low temperature, 1 exhibits a large magnetocaloric effect and 2 shows field-induced multiple magnetic relaxations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new coordination polymer of polyoxomolybdate, {[Cu4(bbp)5Mo6O22]·(H2O)4}∞(bbp = 1,4-bis(benzoimidazol-1-yl)phenyl), has been synthesized under solvothermal reaction, which represents a double-bridging interpenetrating α-Po network based on the bimetallic cluster {Cu4Mo6}. The thermogravimetric and electrochemical behaviors have also been studied. [ABSTRACT FROM AUTHOR]

The hydrothermal reaction of Ni(NO3)2·6H2O, NaN3phenanthroline and nicotinic acid yielded a one-dimensional (1D) complex, [Ni1.5(N3)2(phen)(nic)]n(1) (phen = phenanthroline, nic = nicotinate), which is a new example of the named orbital countercomplementarity-like complex. In 1, the nicotinate shows μ3-nic-N,O,Ocoordination mode, and the azide groups adopt μ1,1bridging mode linking NiIIions to form a rare trinuclear NiIIunit bridged by a double μ1,1azido. [ABSTRACT FROM AUTHOR]

A new 3D MnIIcoordination polymer, [Mn2(HCO2)(L)2(N3)·MeOH]∞(1) (L= nicotinate N-oxide), was synthesized by a solvothermal reaction and characterized magnetically. Complex 1is a typical antiferromagnet with alternating azide/azide/formate/formate bridges, exhibiting a new –J1J1J2J2– coupling sequence. This is the first complex to contain an azide, formate and another type of carboxylate ligand. [ABSTRACT FROM AUTHOR]