Structural diversity and luminescence sensing of cadmium coordination polymers derived from 5-(bis(4-carboxybenzyl)amino) isophthalic acid

Abstract

Reactions of cadmium ions with the flexible tetracarboxylic ligand, 5-(bis(4-carboxybenzyl)amino) isophthalic acid (H4L) gave rise to four complexes, namely {[(Me2NH2)2Cd3(L)2]∙10H2O)}n (1), {[Cd2(L)(pdp)(H2O)2]∙2DMF·4H2O}n (pdp = 4-[(E)-4-Pyridinylazo]pyridine) (2), {[Cd2(L)(bpe)(H2O)2]∙2DMF·4H2O}n (bpe = 1,2-bi(4-pyridyl)ethene) (3) and {[Cd4(L)2(bpmp)3]∙2H2O}n (bpmp = N,Nʹ-bis-(4-pyridyl-methyl) piperazine) (4). Compound 1 features a three-dimensional anionic architecture constructed by triangular Cd3 cluster and ligands, with rectangle channels encapsulating [Me2NH2]+ cations. Compounds 2 and 3 present similar structures, exhibiting the 2D polythreading layer. Compound 4 possesses a 3D structure with 4,6-connected new topology. The powder X-ray diffraction, the thermal stabilities, and solid-state luminescence properties were studied for 1–4. Furthermore, the luminescent sensing of compounds 1 and 4 toward nitrobenzene has also been investigated.