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Metal organophosphonates have been explored in energy-related fields due to their high chemical and thermal stability as a type of uniformly precursor, but only few of pristine metal organophosphonate are directly used for oxygen evolution reaction (OER) catalysts. Here, a mixed-valence iron phosphonate (Fe3-ppat) has been constructed and applied to OER catalysis considered the potential active sites in pillars FeII(H2O)4(COO)2 and inorganic layers FeIII(μ2–OH)PO3. Specifically, isostructural trimetallic framework Fe1.7Co0.3Ni1.0-ppat possesses a minimum overpotential (291 mV), small Tafel slope (91.65 mV dec−1), and high stability up to 83 h. The enhanced catalytic performance could be mainly ascribed to the synergistic effect of NiII equivalent occupancy in pillars and Co/FeIII in layers.

Titanium-oxide or polyoxotitanate clusters are a new type of inorganic host materials that can encapsulate inorganic molecules or ions. We report herein a (NH4)4(enH2)[Ti18O27(PhCOO)24(en)9] molecular cage (Ti18) that encapsulates an entire organic ethylenediamine (en) ion. A thorough investigation has revealed the extraordinary versatility of en. Besides being a guest cation, it also functions as chelating and bridging ligand. It balances the charge of the negative Ti18 cage and facilitates the deprotonation of benzoic acid at the early stage of the reaction as well. DFT calculation and a derivative of Ti18 with open sites at its equatorial position shed further light on the formation mechanism. Ti18 strongly absorbs visible light as a result of en coordination, and it exhibits superior photocatalytic activity compared to anatase TiO2.

The design and utilization of dual sites for synergistic catalysts has been recognised as an efficient method towards high-efficiency catalysis in the cyanosilylation of aldehydes, which gives key intermediates for the synthesis of a number of valuable natural and pharmaceutical compounds. However, most of the reported dual-site catalysts for this reaction were homogeneous, accompanied by potential deactivation through internal complexation of the dual sites. Herein, by the rational selection of an uncoordinated tertiary nitrogen based tricarboxylic ligand (tris[(4-carboxyl)-phenylduryl]amine, H3TCBPA), a new three-dimensional calcium-based metal-organic framework (MOF), Ca3(TCBPA)2(DMA)2(H2O)2 (1, where TCBPA = ionized tris[(4-carboxyl)-phenylduryl]amine and DMA = N,N-dimethylacetamide), possessing accessible dual catalytic sites, Lewis-basic N and Lewis-acidic Ca, has been designed and constructed by a one-pot solvothermal reaction. As expected, 1 is capable of dually and heterogeneously catalysing the cyanosilylation of aldehydes at room temperature, and can be reused for at least 6 runs with a maximum turnover number (TON) of 1301, which is superior to most reported cases. Additionally, 1 shows CO2 adsorption ability and conversion with epoxides, which is beneficial for the establishment of a sustainable society.

Discrete supertetrahedral clusters of metal chalcogenides are rare because of the difficulty involved in meeting global charge matching between the negative charge of the skeleton and counterion. We present herein the third type of a discrete chalcogenide cluster with a double T3 structure in the compound (HDBN)6[In20S33(DBN)6] (DBN = 1,5-diazabicyclo [4.3.0]-5-nonene), the anion of which features quasi-D3 symmetrical double-T3 In20S33 supertetrahedra with six cornered indium atoms coordinated by DBN molecules. DFT theory calculations of the interaction between host and guest show that this compound may have high kinetic stability and low photoelectric reactivity.

Exploring efficient and stable oxygen evolution reaction (OER) catalysts with earth-abundant elements has been an urgent task in water splitting. Metal-organic frameworks (MOFs), possessing abundant active metal sites and tunable porous crystalline structures, are promising as OER catalysts. In this paper, a MOF based on benzotriazole-5-carboxylate (Co3-btca) that contains unsaturated coordinated metal centers and a 1D channel was selected to act as an OER catalyst. To optimize the OER performance, isostructural bimetallic and trimetallic frameworks were obtained by doping with Fe and/or Ni ions. The optimized Co2.36Fe0.19Ni0.45-btca possesses the lowest overpotential of 292 mV at 10 mA cm-2 and a small Tafel slope of 72.6 mV dec-1. The enhanced catalytic performance could be attributed to the synergistic effect between the unsaturated coordinated Co, Fe and Ni sites, which are beneficial for the nucleophilic attack of OH- forming adsorption intermediates.

Reactions of CuCl2, K2[Ni(CN)4]/K3[Co(CN)6], and 5-amino-1H-tetrazole led to cyanide-bridged mixed-valence Cu(II/I) complexes, [Cu(H2O)3Cu3(CN)5] (1) and [Cu(H2O)4][Cu4(CN)6] (2).The uncommon semi-closed {Cu2(CN)3} dimmers in 1 are bridged by μ3-C,C,N cyanide ligands to afford rare 1D centipedal-like chain motifs, which are further bridged by μ2-C,N and metalloligand “CN–Cu(4)–CN” to finish sophisticated zeolite-like 3-D structure. Topologically, 1 is the first example of uninodal 7-connected sev-like cyanide-bridged network. Compound 2 consists of two-dimensional honeycomb-related anionic layers [Cu4(CN)6]2 −, within which the [Cu(H2O)4]2 + cations are intercalated into alternate interlamellar space. Compound 1 shows antiferromagnetic couple arising from pure ground-state configuration of Cu(II) mediated by diamagnetic bridges –CN–CuI–CN −. The inclusion compound 2 shows blue photoluminescence originated from Cu(I) center to the unoccupied π* orbital of the cyanide ligand (MLCT) charge transfer.

Solvothermal reactions of metal salts, 3-amino-1,2,4-triazole-5-carboxylic acid (H2atzc) and ammonium oxalate in different temperature produced two metal azolate frameworks, namely, [Cu3(atzc)2(atz)(ox)]·1.5H2O (1) and [Co5(atz)4(ox)3(HCOO)2]·DMF (2) (H2atzc=3-amino-1,2,4-triazole-5-carboxylic acid, Hatz=3-amino-1,2,4-triazole, and ox=oxalate), in which the atzc precusor was in situ decarboxylated. Structural determination reveals that 1 contains [Cu3(atzc)2(atz)]2− layers of mixed μ4-atzc and μ3-atz ligands, which are pillared by ox2− groups to form a 3D porous framework. Compound 2 contains 2D layers with basic spindle-shaped decanuclear units, which extended by ox2− and formates to form 3D porous framework. Gas adsorption investigation revealed that two kinds of frameworks exhibited selective CO2 over N2 sorption. Moreover, activated 2 shows H2 storage capacity. Additionally, magnetic properties of both the compounds have been investigated.

Although a variety of functional metal-organic frameworks (MOFs) have been synthesized, post-modified, and applied in various areas, there is little knowledge about how molecular cluster building units are stepwise evolved into MOFs via intermediates. Coordination bonds are generally stronger than hydrogen bonds, and thus equivalent replacement of X-H···Y hydrogen bonds by X-M-Y coordination bonds can transform hydrogen bond networks into MOFs. In this work, solvothermal in situ reduction reactions of CuBr2 and 1,4-diazoniabicyclo[2,2,2]octane (DABCO) generated a myriad of tunable photoluminescent cuprous body-centered cubic bromide cluster-based networks with the general formula [Cu4+xH4-xBr6(DABCO)4](HCO2)2·S (x = 0, 0.56, 0.81, 1.27, 1.39, 2.56, 2.78, and 4 for compounds 1-8, respectively). All of these compounds crystallize in the cubic space group with the largest volume difference being only 5.2%, but they belong to three remarkably different kinds of crystals. Complex 1 is a molecular crystal and consists of tetrahedral [Cu4Br6(HDABCO)4](2+) clusters with monodentate HDABCO groups that are supported via N-H···Br synthons in the hydrogen bond network. Compound 8 is a [Cu8Br6](2+) cube cluster-based MOF with bridged DABCO ligands. Complexes 2-7 are seemingly impossible Cu/H-substituted solid solutions of 1 and 8. The CuBr framework components in 1-8 are Cu4Br6, Cu4.56Br6, Cu4.81Br6, Cu5.27Br6, Cu5.39Br6, Cu6.56Br6, Cu6.78Br6, and Cu8Br6, respectively. Crystallization kinetics studies revealed that the [Cu4Br6(HDABCO)4](2+) cluster-based hydrogen bond network (1) was initially formed such that N-H···Br hydrogen bonds could be stepwise replaced by N-Cu-Br coordination bonds to form the [Cu8Br6](2+) cube cluster-based MOF (8) via solid solutions. These observations directly reveal the equivalence and transformation between the N-H···Br hydrogen bond and the N-Cu-Br coordination bond and the evolutionary mechanism of a molecular crystal to a MOF via solid solutions, which is of fundamental importance in materials but has never before been revealed. DFT calculations suggest that equivalent replacement of a N-H···Br hydrogen bond by a N-Cu-Br coordination bond is exothermic and exergonic, which also supports the transformation from molecule 1 to MOF 8.

Two cuprous iodide polymorphs formulated as [N(CH3)4][Cu2I3] α and β were synthesized, in which N(CH3)4+ template that never existed in the reaction materials are in situ generated via cleavage of C N bonds and N-alkylation reactions. Solvothermal reaction of copper source, hexamethylenetetramine and HI in methanol solution at 150 °C led to α and β polymorphs. Two polymorphs have been synthesized via subtle modification of the experimental condition, which indicates that the small force is also sufficient for energy difference for polymorphs. α polymorph contains one-dimensional Cu2I3− chain in which the copper atoms are arranged into a zigzag lattice; β polymorph is composed of novel ladder-like chains which can be considered as being built up by Cu12I18 and Cu2I3 two types of secondary building units. The UV–vis absorption spectra for α and β polymorphs were investigated in reflectance mode in the solid state at room temperature, exhibiting that they belong to potential semiconductors. The excitation and emission in α and β are very distinct, which highlight that the molecular packing in polymorphs is critical to photophysical properties.

Reactions of CuCl2, K3[Fe(CN)6]/K4[Fe(CN)6], and pyrazine (pyz) in water solution at 160 °C/170 °C for 6 days led to two luminescent supramolecular isomers with stoichiometry [Cu2(pyz)(CN)2]·[CuCN] (1 and 2), which show 3D pseudopolyrotaxane structures with 1D [Cu(CN)]∞ chains penetrating 2D [Cu2(pyz)(CN)2] sheets. Isomer 1 contains linear, trigonal, and tetrahedral Cu(I) atoms, which are linked by pyz and cyanide groups into unprecedented (3,4)-connected Shubnikov-type (5,34) sheets, and these sheets are penetrated by [Cu(CN)]∞ chains via unsupported CuI–CuI interactions. In contrast, the [Cu2(pyz)(CN)2] sheets in isomer 2 can be viewed as a classical (6,3)-topological brick wall layer, which are also penetrated by [Cu(CN)]∞ chains in the absence of cuprophilicity. Schematically, the brick wall and Shubnikov-type (5,34) nets can be formed via arrangement of brick rows in ABAB and ABBA modes, respectively. It is worth noting that cyanide sources played a crucial role in the formation of supramolecular iso...

Hydrothermal reaction of copper(II) chloride with 2-hydroxypyrimidine generated double salt of [Cu2Cl(μ4-pymo)] (1) (Hpymo = hydroxylpyrimidine) while hydrothermal treatment of CuCl2, NaN3 and acetonitrile resulted in double salt of [Cu2(mtta)Cl] (2) (Hmtta = 5-methyltetrazole) in which in situ [2 + 3] cycloaddition reactions of acetonitrile with azide formed mtta ligand. X-ray single crystal structural analyses revealed that 1 shows a two-dimensional layer formed by fusion of one-dimensional [ Cu 2 ( opym ) ] n n + and [ Cu 2 Cl ] n n + structural motifs. The two-dimensional layers in 1 are held together by C–H⋯Cl hydrogen bonds to form three-dimensional supramolecular array. Compound 2 has a three-dimensional framework constructed from [ Cu 2 ( mtta ) ] n n + ribbons and [Cu8Cl4]4+ units. Uncommon coordination modes of μ4-1,2κO:3κN:4κN′ pymo and μ4-Cl (Cl at the apex of a Cu4Cl square pyramid) in 1 and μ4-η1:η1:η1:η1 mtta in 2 were also observed. The short Cu(I)⋯Cu(I) distances were found in 1 and 2, indicating the existence of Cu(I)⋯Cu(I) interactions.

Two isostructural mixed-valence vanadium phosphonoacetates H2(DABCO)[VIVO(H2O)VIII(OH)(O3PCH2CO2)2]·2.5H2O (1) and H2(PIP)[VIVO(H2O)VIII(OH)(O3PCH2CO2)2]·2.5H2O (2) have been synthesized. They crystallize in the orthorhombic space group Pnna with a = 7.0479(10) A, b = 15.307(2) A, and c = 17.537(3) A for 1 and a = 7.0465(9) A, b = 15.646(2) A, and c = 17.396(2) A for 2. X-ray single-crystal diffraction reveals that 1 and 2 have a three-dimensional open framework featuring 16-ring ellipsoid channels that are filled with doubly protonated 1,4-diazabicyclo[2,2,2]octanium/piperazinium cations and water molecules. According to the classification in metal−organic frameworks, 1 and 2 contain infinite (−O−V−)∞ chains that are cross-linked by “metalloligand” [VO(H2O)(O3PCH2CO2)2]4- into a 3-D net of the sra topology. The temperature dependence of the magnetic susceptibility of 1 shows that the χmT value in the range of 60−320 K is constant of 1.105 cm3 K mol-1/V2 unit, and upon further cooling, the χmT value rapid...

Hydrothermal reaction of CuBr2, 4,4′-bipyridine and ethanol/methanol generated two copper (I) bromide complexes with in situ alkylated 4,4′-bipyridium, namely [C14H18N2][Cu5Br7] (1) and [C12H14N2][Cu4Br6] (2). The structure of 1 consists of Cu 5 Br 7 2 - chains and N,N′-diethyl-4,4′-bipyridinium. The underlying structural motif in Cu 5 Br 7 2 - of 1 is the Cu5Br capped square pyramid, which is different from the Cu5Br2 pentagonal bipyramidal structural motif in various documented Cu 5 Br 7 2 - anions. The Cu 5 Br 7 2 - in 1 contains untypical μ5-bromide, with which five copper atoms forms a capped square pyramid rather than a pentagonal pyramid as predicted by Subramanian and Hoffmann. Compound 2 is isostructural with [C12H14N2][Cu4Cl6] reported by Willett, and consists of Cu 4 Br 6 2 - chains and N,N′-dimethyl-4,4′-bipyridinium. The Cu 4 Br 6 2 - chain is composed of alternating Cu6Br6 and Cu2Br6 units.

Colorless needle-like crystals of α-(NMe4)[Cu2I3] are prepared by solvothermal reaction of CuI, hexamethylenetetramine, and HI in MeOH in a molar ratio of 5:2:7:150 (autoclave, 150 °C, 120 h; 61% yield).

The first coordination polymer of 2,2′-oxydisuccinate, [Cd2(meso-odsc)(H2O)] (odsc = meso-2,2′-oxydisuccinate), was hydrothermally synthesized from CdSO4 and D,L-malic acid; X-ray crystallography shows that the D,L-malic acid was transformed in situ into meso-odsc via intermolecular dehydration coupling.

Five new cuprous halides formulated as [etpy][Cu(3)I(4)] 1, [mepy][Cu(2)Br(3)] 2, [mepy][Cu(2)I(3)] 3 [dmebpp][Cu(7)Br(9)] 4 and [dmeDABCO](4)[Cu(8)I(16)] 5 (etpy = N-ethylpyridyl; mepy = N-methylpyridyl; dmebpp = N,N'-dimethyl-1,3-bis(4-pyridyl)propane; dmeDABCO = N,N'-dimethyl-1,4-diazabicyclo-[2.2.2]octane) have been prepared by solvothermal reactions of a copper source, halides and N-heterocyclic ligands in alcoholic solution. 1 contains an unprecedented trigonal two-dimensional cuprous halide layer Cu(3)I(4)(-) constructed from trimeric Cu(3)I(8) units via sharing peripheral mu(3)-iodines; isostructural 2 and 3 contain infinite Cu(2)X(3)(-) chains in which the copper atoms are arranged into a ladder; 4 is composed of novel twofold helical cuprous halide chains Cu(7)Br(9)(2-) built up by CuBr(4) and CuBr(3); 5 contains an infinite edge-sharing tetrahedral chain with a periodic sequence of eight CuI(4) tetrahedra. In situ alkylation reactions of N-heterocycles with alcohols generated organic cationic templates, which played an important role in the control of the structures of anionic cuprous halides. A possible alkylation mechanism of N-heterocycles in the system has been proposed. The fluorescence properties of 1 and 4 were investigated. Time-dependent density functional theory (TD-DFT) calculations were carried out on the excited electronic states 1 of in order to understand the emission mechanism.