Polycatenation and self-penetration in nitrobenzene-detecting zinc and cadmium 4-carboxylatomethylbenzoate coordination polymers with dipyridylurea coligands

Abstract

Hydrothermal reaction of zinc or cadmium nitrate, 4-(carboxylatomethyl)benzoic acid (cmbH2), and bis-(4-pyridyl)urea (bpu) generated a pair of coordination polymers that were isolated and subsequently structurally characterized by single-crystal X-ray diffraction. {[Zn2(cmb)2(bpu)2]·2H2O}n (1) shows a 2D + 2D → 3D parallel polycatenated pattern of sawtooth (4,4) coordination polymer grids. In contrast, {[Cd3(cmb)3(bpu)2(H2O)4]·3H2O}n (2) manifests [Cd3(cmb)3(H2O)4]n slab motifs threaded and linked by bpu ligands into an unprecedented self-penetrated 3,3,4,4-connected 3D network with (6·7·8)(627)(627·83)(7383) topology. Thermal decomposition of the new phases is discussed. Both 1 and 2 underwent visible light luminescence upon ultraviolet irradiation, and acted as luminescent “turn-off” sensors for nitrobenzene absorption in ethanol suspension.