Temperature-induced Sn(II) supramolecular isomeric frameworks as promising heterogeneous catalysts for cyanosilylation of aldehydes

Diamondoid Ni(II) Coordination Polymer as an Electrocatalyst for Hydrogen and Oxygen Evolution Reactions and Overall Water Splitting

We have successfully synthesized a new Ni(II)-based coordination polymer (CP) [Ni2(cis-1,4-chdc)2(4,4'-bpy)3(H2O)2] (1); (cis-1,4- H2chdc=cis-1,4-cyclohexanedicarboxylic acid and 4,4'-bpy=4,4'-bipyridine) employing slow diffusion method in a single pot technique. The connectivity of Ni(II) ions and bridging cis-1,4-chdc ligand gives rise to a three-dimensional (3D) framework with 2-fold interpenetrated diamondoid topology. Interestingly, the synthesized CP acts as efficient catalyst for electrocatalytic water splitting. The water oxidation activity of compound 1 exhibits Tafel slope equivalent to 361.48 mV.dec-1 for hydrogen evolution reaction (HER) and 353.53 mV.dec-1 for oxygen evolution reaction (OER) in an alkaline medium while almost similar values of Tafel slope for HER and OER equivalent to 287.33 mV.dec-1 and 289.93 mV.dec-1 respectively in acidic medium. Thus, the compound 1 has excellent efficacy in catalyzing HER and OER in acidic as well as alkaline medium, which is ascribed to its distinctive 3D architecture.

Alkoxy-Functionalized Hydroxamate/Zinc Metal-Organic Frameworks and the Effects of Substituents and Acid Addition on Their Structures

Single crystals of alkoxy-functionalized hydroxamate/zinc metal-organic frameworks (MOFs) were obtained by fixating the hydroxamate moiety via intramolecular hydrogen bonding. The resulting MOF structures depend on the steric demand of the alkoxy groups, whereby the incorporation of bulky isopropyl groups affords porous hydroxamate/zinc MOFs. The topological structures of the isopropyl-substituted MOFs could be controlled by adding acid.

Thiazolo[5,4-d]thiazole-Based Metal-Organic Framework for Catalytic CO2 Cycloaddition and Photocatalytic Benzylamine Coupling Reactions

Metal-organic frameworks (MOFs) with permanent porosity and multifunctional catalytic sites constructed by two or more organic ligands are regarded as effective heterogeneous catalysts to improve certain organic catalytic reactions. In this work, a pillared-layer Zn-MOF (MOF-LS10) was constructed by 2,3,5,6-tetrakis(4-carboxyphenyl)pyrazine (H4TCPP) and 2,5-di(pyridin-4-yl)thiazolo[5,4-d]thiazole (DPTZTZ). After activation, MOF-LS10 has a permanent porosity and moderate CO2 adsorption capacity. The introduction of thiazolo[5,4-d]thiazole (TZTZ), a photoactive unit, into the framework endows MOF-LS10 with excellent photocatalytic performance. MOF-LS10 can not only efficiently catalyze the formation of cyclic carbonates from CO2 and epoxide substrates under mild conditions but also can photocatalyze benzylamine coupling at room temperature. In addition, we used another two ligands 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (H4BTEB) and 1,4-di(pyridin-4-yl)benzene (DPB) to synthesize MOF-LS11 (constructed by BTEB4- and DPTZTZ) and MOF-LS12 (constructed by TCPP4- and DPB) in order to explore whether the pyrazine structural unit and the TZTZ structural unit synergistically catalyze the reaction. The electron paramagnetic resonance spectrum demonstrates that the superoxide radical (·O2-), generated by electron transfer from the MOF excited by light to the oxidant, is the main active substance of oxidation. The design and synthesis of MOF-LS10 provide an effective synthetic strategy for the development of versatile heterogeneous catalysts for various organic reactions and a wide range of substrates.

A novel luminescent phosphor of a metal–organic framework with orange-red emission

A novel metal–organic framework (compound 1) was rationally designed and successfully constructed using carboxylic acid and pyridine derivatives as bilinkers, possessing good photoluminescence properties with orange-red emission.

Two isomeric metal-organic frameworks bearing stilbene moieties for high volatile iodine uptake

The efficient, green, and economical removal of radioactive iodine (I2) has drawn worldwide attention in the safe development of nuclear energy. Metal-organic frameworks (MOFs) have been demonstrated to be a...

Synthesis, crystal structures and reversible solid-state crystal-to-crystal transformation of three isostructural lead(ii) halide coordination polymers with different luminescence properties in bulk and nanoscale

Novel isostructural lead(ii) halide CPs have been synthesized in bulk and nanoscale. The compounds exhibited reversible solid-state CTC transformations under mechanochemical reactions. The CPs displayed different thermal and fluorescence properties.

Structural Transformation of Copper Coordination Complexes with Inducing Supramolecular Chirality

Four copper coordination complexes [CuL(CH3OH)]n (1), [CuL(C2H5OH)]n (2), [(CuL)·0.5H2O]n (3), and [CuL(H2O)·0.5H2O]n (4) with a tridentated Schiff base ligand (H2L = (E)-2-((4-fluoro-2-hydroxybenzylidene)amino)acetate) were obtained in different solvents and reaction times....

Collaboratively boosting charge transfer and CO2 chemisorption of SnO2 to selectively reduce CO2 to HCOOH

In this study, we have facilely developed a SnO₂-based electrocatalyst (SnO₂-V_O@N-C), which can combine together the favorable structure features of oxygen vacancies, porosity, and full-coating with N-doped carbon layers (N-C). Our experimental and theoretical calculation results indicated that with the facile engineering of oxygen vacancies and the full-coating of the N-doped carbon layer, the adsorption/activation of CO₂ and charge transfer can be promoted in the CO₂ reduction process, making SnO₂-V_O@N-C the electrocatalyst with improved activity and selectivity (FE_HCOOH = 84%) toward the reduction of CO₂ to HCOOH.

Novel Ba2+ and Pb2+ metal-organic frameworks based on a semi-rigid tetracarboxylic acid: syntheses, structures, topologies and luminescence properties

Multidentate carboxylate ligands have been widely used in the construction of metal-organic frameworks (MOFs) owing to the rich variety of their coordination modes, which can lead to crystalline products with interesting structures and properties. Two new main-group MOFs, namely, poly[[di-μ-aqua-diaqua(dimethylformamide)[μ₇-5,5'-methylenebis(2,4,6-trimethylbenzene-1,3-dicarboxylato)]dibarium(II)] trihydrate], {[Ba₂(C₂₃H₂₀O₈)(C₃H₇NO)(H₂O)₄]·3H₂O}_n or {[Ba₂(BTMIPA)(DMF)(H₂O)₄]·3H₂O}_n (1), and poly[[diaqua[μ₆-5,5'-methylenebis(2,4,6-trimethylbenzene-1,3-dicarboxylato)]dilead(II)] 2.5-hydrate], {[Pb₂(C₂₃H₂₀O₈)(H₂O)₂]·2.5H₂O}_n or {[Pb₂(BTMIPA)(H₂O)₂]·2.5H₂O}_n (2), were prepared by the self-assembly of metal salts with the semi-rigid tetracarboxylic acid ligand 5,5'-methylenebis(2,4,6-trimethylisophthalic acid) (H₄BTMIPA). Both structures were characterized by elemental analysis (EA), single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), IR spectroscopy and thermogravimetric analysis (TGA). Complex 1 reveals a three-dimensional (3D) flu network formed via bridging tetranuclear secondary building units (SBUs) and complex 2 displays a 3D framework with an sqp topology based on one-dimensional metal chains. The BTMIPA^4- ligands adopt a rare coordination mode in 2, although the ligands in both 1 and 2 are X-shaped. The luminescence properties of both complexes were investigated in the solid state.

Soluble imidazolium-functionalized coordination cages for efficient homogeneous catalysis of CO2 cycloaddition reactions

The soluble metal–organic cage ImBDC-Co can be employed as a homogeneous catalyst for the CO₂ cycloaddition reaction, and shows higher catalytic activity than its heterogeneous counterparts. Moreover, the soluble cage can realize recovery and reuse without activity loss.

Bonded- and discreted-Lindqvist hexatungstate-based copper hybrids as heterogeneous catalysts for the one-pot synthesis of 2-phenylquinoxalines via 2-haloanilines with vinyl azides or 3-phenyl-2H-azirines

One bonded- and one discreted-Lindqvist hexatungstate-based copper hybrids (Cu-POMs) ([Cu2(O)OH(phen)2]2[W6O19]·6H2O (1) and [Cu2(phen)4Cl] [HW6O19]·2H2O (2) (phen = 1,10-phenanthroline)) were controllably synthesized and routinely characterized. Cu-POMs 1-2 consisted of identical [W6O19] unit and similar copper-phen complexes, the two units are bonded via four Cu-O chemical bonds in compound 1; however, compound 2 is discreted and stabilized by intermolecular electrostatic interactions. Importantly, these Cu-POMs catalysts were first applied in the novel reaction for the preparation of 2-phenylquinoxalines via the one-pot coupling and oxidation reactions of 2-haloanilines with vinyl azides or 3-phenyl-2H-azirines under mild conditions, and Cu-POMs 1 showed higher catalytic performance in good yields (79-84%). The reactions exhibit some functional group tolerance and allow for the preparation of a number of 2-phenylquinoxalines.

A one-dimensional infinite silver alkynyl assembly [Ag8(C[triple bond, length as m-dash]C t Bu)5(CF3COO)3(CH3CN)] n : synthesis, crystal structure and properties

A high-yield silver alkynyl assembly [Ag8(C[triple bond, length as m-dash]C t Bu)5(CF3COO)3(CH3CN)] n (1) constructed from [AgC[triple bond, length as m-dash]C t Bu] n ligand, CF3COOAg and CH3CN auxiliary ligands with a one-dimensional infinite chain structure has been obtained in one pot. Compound 1 has been well-defined and characterized. The photocurrent properties and the temperature-sensitive luminescent properties of 1 have been investigated.