High-Throughput Study of the Cu(CH₃COO)₂·H₂O−5-Nitroisophthalic Acid−Heterocyclic Ligand System: Synthesis, Structure, Magnetic, and Heterogeneous Catalytic Studies of Three Copper Nitroisophthalates

Abstract

A high-throughput screening was employed to identify new compounds in Cu(CH3COO)2·H2O−NIPA−heterocyclic ligand systems. Of the compounds identified, three compounds, [Cu3{(NO2)−C6H3−(COO)2}3(C3N6H6)] (I), [Cu2(μ3-OH)(H2O){(NO2)−C6H3−(COO)2}(CN4H)]·(H2O) (II), and [Cu2(μ3-OH)(H2O){(NO2)−C6H3−(COO)2}(CN5H2)]·2(H2O) (III), have been isolated as good quality single crystals by employing conventional hydrothermal methods. Three other compounds, Cu2{(NO2)−C6H3−(COO)2}(CN4H)(H2O) (IIa), Cu2{(NO2)−C6H3−(COO)2}(CN5H2) (IIIa), and Cu2{(NO2)−C6H3−(COO)2}{(CN5H2)2}2H2O (IIIb), were identified by a combination of elemental analysis, thermogravimetric analysis (TGA), and IR spectroscopic studies, although their structures are yet to be determined. The single crystalline compounds were also characterized by elemental analysis, TGA, IR, UV−vis, magnetic, and catalytic studies. The structures of the compounds have paddle wheel (I) and infinite Cu−O(H)−Cu chains (II and III) connected with NIPA and heterocyclic ligands forming two- (II) and three-dimensional (I and III) structures. The bound and lattice water molecules in II and III could be reversibly removed/inserted without affecting the structure. In the case of II, the removal of water gives rise to a structural transition, but the dehydrated phase reverts back to the original phase on prolonged exposure to atmospheric conditions. Magnetic studies indicate an overall antiferromagnetism in all of the compounds. Lewis acid catalytic studies indicate that compounds II and III are active for cyanosilylation of imines.