Syntheses, Characterization, and Properties of Three-Dimensional Pillared Frameworks with Entanglement

Abstract

Six new coordination polymers, namely, [Cd 3 (L) 2 (dpa) 2 (H 2 O)] ( 1 ), [Co 3 (L) 2 (dpa) 2 (H 2 O) 2 ]·H 2 O ( 2 ), [Cd(L)(chda) 0.5 ] ( 3 ), [Cd(L)(dc) 0.5 (H 2 O)] ( 4 ), [Cd 2 (L) 2 (cca)]·2H 2 O ( 5 ), and [Cd 2 (L) 2 (cppa)]·2H 2 O ( 6 ) [HL = 3,5-di(imidazol-1-yl)benzoic acid, H 2 dpa = diphenic acid, H 2 chda = 1,4-cyclohexanedicarboxylic acid, H 2 dc = 1,4-benzenediacrylic acid, H 2 cca = 4-carboxycinnamic acid, H 2 cppa = 3-(4-carboxyphenyl)propionic acid] have been obtained under hydrothermal conditions. Complexes 1 and 2 are novel (3,6)-connected three-dimensional (3D) frameworks based on trinuclear subunits. Complex 3 shows a rare 4-fold interpenetrating 3D dmc net, and 4 features a uninodal 6-connected 3D self-penetrating framework. Both 5 and 6 possess unusual 3-fold interpenetrating 3D (3,4)-connected InS nets. In 1 − 6 each metal atom is coordinated by the combination of L − and auxiliary carboxylate ligands. In 1 and 2 the auxiliary carboxylate ligand plays an important role in the formation of metal cluster based subunits. In 3 − 6 the auxiliary carboxylate ligands pillar the metal - L − two-dimensional networks to form entangled 3D frameworks. Furthermore, the photoluminescence and thermal stabilities of complexes 1 − 6 were investigated. The temperature-dependent magnetic susceptibility measurements of compound 2 show the ferromagnetic interactions between the metal centers mediated through the μ-O and/or O−C−O linkages.