A new 3D transition-metal complex-templated framework based on Wells–Dawson polyoxometalate and copper(I)–pyrazine moieties

A novel μ3-CO3 bridged linear polymeric Cu-complex ([Cu3(DMAP)8(μ3-CO3)2]I2) n ·xH2O: synthesis, characterization and catalytic applications in the synthesis of phenoxypyrimidines and arylthiopyrimidines via C-O and C-S cross-coupling reactions

This manuscript reports on the synthesis and characterization of a new polymeric copper complex ([Cu3(DMAP)8(μ3-CO3)2]I2) n ·xH2O and its successful application in C-O and C-S cross coupling reactions for the synthesis of biologically important phenoxypyrimidine and arylthiopyrimidine scaffolds. In an attempt to synthesize [Cu(DMAP)4I]I by adopting a procedure reported by Roy et al. with slight modification, the authors discovered a new polymeric Cu-complex that contains μ3-CO3 bridges. The polymeric linear structure of the complex was established using single crystal X-ray analysis. FT-IR, UV-vis and DSC studies were also performed on the polymeric complex. This novel polymeric Cu-complex was found to efficiently catalyse C-O/C-S cross coupling reactions between chloropyrimidines and phenols/thiophenols in an aqueous medium within a short reaction time, delivering their corresponding phenoxypyrimidines and arylthiopyrimidines. Using this protocol, 22 phenoxypyrimidines and 6 arylthiopyrimidines were successfully synthesized. The synthesized novel compounds were well characterized using 1H and 13C NMR spectroscopy and HRMS analysis and were screened for their drug-likeness properties using the SwissADME webtool.

Beyond π-π Stacking: Understanding Inversion Symmetry Breaking in Crystalline Racemates

The design of noncentrosymmetric (NCS) solid state materials, specifically how to break inversion symmetry between enantiomers, has intrigued chemists, physicists, and materials scientists for many years. Because the chemical complexity of molecular racemic building units is so varied, targeting these materials is poorly understood. Previously, three isostructural racemic compounds with a formula of [Cu(H₂O)(bpy)₂]₂[MF₆]₂·2H₂O (bpy = 2,2'=bipyridine; M = Ti, Zr, Hf) were shown to crystallize in the NCS space group Pna2₁, of polar, achiral crystal class mm2. In this work, we synthesized five new racemic compounds with the formula [Cu(H₂O)(dmbpy)₂]₂[MF₆]₂·xH₂O (dmbpy = 4,4'/5,5'-dimethyl-2,2'-bipyridine; M = Ti, Zr, Hf). Single crystal X-ray diffraction reveals that the five newly synthesized compounds feature equimolar combinations of Δ- and Λ-Cu(dmbpy)₂(H₂O)²⁺ complexes that are assembled into packing motifs similar to those found in the reported NCS structure but all crystallize in centrosymmetric (CS) space groups. Seven structural descriptors were created to analyze the intermolecular interactions on the assembly of Cu racemates in the CS and NCS structures. The structural analysis reveals that in the CS structures, the inversion center results from parallel heterochiral π-π stacking interactions between adjacent Cu racemates regardless of cation geometries, hydrogen bonding networks, or interlayer architectures, whereas in the NCS structure, nonparallel heterochiral π-π interactions between the adjacent Cu racemates preclude an inversion center. The parallel heterochiral π-π interactions in the CS structures can be rationalized by the restrained geometries of the methyl-substituted ligands. This work demonstrates that the introduction of nonparallel stacking can suppress the formation of an inversion center for an NCS racemate. A conceptual framework and practical approach linking the absence of inversion symmetry in racemates is presented for all NCS crystal classes.

Two unusual 3D honeycomb networks based on Wells–Dawson arsenomolybdates with d10 transition-metal-pyrazole connectors

Two unusual 3D honeycomb networks based on Wells–Dawson arsenomolybdates were first reported, which have highly efficient catalytic ability for the degradation of organic dyes under UV irradiation and obvious electrocatalytic activities for the reduction of H₂O₂.

Polyoxometalate Insertion into Cu–pz Porous and Cu-bim Knighthead Coordination Polymers: [{Cu4(pz)5.5}{Cu2(2,2'-bim)3}0.5{P2W18O62}]·H2O

The structure of crystallised {[Cu4(pz)5.5][Cu2(2,2′-bim)3]0.5[P2W18O62]}·H2O (1) (pz = pyrazine, bim = biimidazole) is reported. The crystal structure is characterised by cage-like pores [Cu8(pz)11]8+ of Cu ions linked through pz ligands. [P2W18O62]6– polyanions are capsulated into cage-like pores of [Cu8(pz)11]8+, forming ‘hamburger’-like units. Furthermore, the three-dimensional framework in 1 is achieved via copper-pyrazolate layers, binuclear copper-biimidazole subunits, and Dawson-type polyoxometalate clusters. The electrochemical properties of compound 1 were also studied in detail.