Two distinct Cd-2,6-bip coordination polymers: Auxiliary ligand affected structures, luminescence and nitrobenzene sensing properties

Abstract

The study on the auxiliary ligands affecting the architectures of 2,6-bip-bridged coordination polymers (CPs) is demonstrated [2,6-bip=2,6-bis(imidazol-1-yl)pyridine]. Two distinct Cd-2,6-bip CPs [Cd(2,6-bip)2(NCS)2]n (1) and {Cd(2,6-bip)[N(CN)2]2}n (2) were constructed in the presence of the auxiliary ligands thiocyanate SCN− and dicyanamide N(CN)2−, respectively. 1–2 were determined by FT-IR, elemental analyses, powder and single crystal X-ray diffractions. 1 exhibits a two-dimensional (2-D) layer structure, only sustained by 2,6-bip single bridges; while 2 has a distinct 2-D layer architecture, supported by 2,6-bip and N(CN)2− double bridges and N(CN)2− single bridges. The luminescence and nitrobenzene sensing properties of 1–2 were investigated, which reveals that 1–2 exhibit significantly stronger luminescence emissions than that of free 2,6-bip organic ligand, and the most sensitive for nitrobenzene detection.