Zinc(II) 2D Coordination Polymer With Terephthalate and 4,6-Bis(Imidazol-1-yl)-2,1,3-Benzoxadiazole Linkers as a Selective Luminescent Probe for Gallium(III) Cations

Abstract

A two-dimensional (2D) zinc(II) coordination polymer CP-1, [Zn(im₂bod)(bdc)]_n (im₂bod = 4,6-bis(imidazol-1-yl)-2,1,3-benzoxadiazole, bdc²⁻ = 1,4-benzenedicarboxylate), was synthesized and fully characterized. CP-1 crystallizes in the monoclinic crystal system, space group P2₁/n. Zn²⁺ ions adopt a four-coordinated distorted tetrahedral geometry. The structure of CP-1 comprises a two-dimensional layer consisting Zn²⁺ cations connected by im₂bod and bdc²⁻ ligands. The adjutant layers participate in π-π stacking interactions via the benzene and 2,1,3-benzoxadiazole rings. CP-1 demonstrated a blue emission with the maximum at 490 nm and a photoluminescence quantum yield 24%. Luminescent sensing properties of CP-1 in aqueous suspension toward metal cations were evaluated, and selective emission quenching response was observed toward Ga³⁺ cations with the limit of detection 10 μM.