Metal–Organic Frameworks Based on Flexible V-Shaped Polycarboxylate Acids: Hydrogen Bondings, Non-Interpenetrated and Polycatenated

Solvothermal reactions of 4,4′-dicarboxydiphenylamine (H2L) with 4,4′-bis(imidazol-1-yl)phenyl (BIP) and 4,4′-bis(imidazol-1-yl)diphenyl (BIBP) in the presence of cobalt(II), cadmium(II), zinc(II) salts in H2O/CH3CN or H2O/DMF produced five new complexes, namely, [Co2(L)2(BIP)2·3H2O] n (1), [Co(L)(BIP)·2CH3CN] n (2), [Co(L)(BIBP)·H2O] n (3), [Cd(L)(BIBP)] n (4), [Zn(L)(BIBP)] n (5). Compound 1 has binuclear Co(II) clusters, which are linked by L2– and BIP to generate a rare three-dimensional (3D) non-interpenetrated cds-type framework, and displays ferromagnetic character. Compound 2 possesses unusual 3-fold 2D → 2D polycatenation of (4, 4) nets. Compound 3 reveals a (4, 4) grid topology with very strong hydrogen bondings due to the abundant uncoordinated carboxyl groups, which load in the structure like a freely dangling arm. Compound 3 also displays weak ferromagnetic character. Compounds 4 and 5 are isomorphic. H2L and BIBP ligands in 4 and 5 interact with a metal center to form wave-like 2D sheets. In addition, the thermal stabilities and photochemical properties of compounds have been studied.