Three Silver(I) Coordination Polymers Based on Pyridyl Ligands and Auxiliary Carboxylic Ligands: Luminescence and Efficient Sensing Properties

Abstract

Easily producible sensors for harmful industrial waste compounds are of significant interest for both human health and the environment. Three novel coordination polymers, [Ag(μ-aca)(μ₄-bztpy)_1/2] (<b>1</b>), [Ag(μ-bza)(μ-bpa)] (<b>2</b>), and [Ag₂(μ-aca)₂(μ-bpa)₂]·EtOH·2H₂O (<b>3</b>), were assembled in this study by reactions using Ag⁺ as a node with the pyridyl ligand 1,2,4,5-tetrakis(4-pyridyl)benzene (bztpy) or 9,10-bis(4-pyridyl)anthracene (bpa) and an auxiliary chelating carboxylic ligand. Single-crystal X-ray structural analyses revealed that compound <b>1</b> has a 3D framework consisting of 1D [Ag(aca)]_∞ chains and bztpy linkers, while <b>2</b> and <b>3</b> have 2D layered structures consisting of binuclear Ag-carboxylate units and bpa linkers, respectively. Topological studies revealed that <b>1</b> has a <b>bbf</b> topology, while <b>2</b> and <b>3</b> are 2D [4,4] rhombic grids. The compounds were further characterized by powder X-ray diffraction, IR, elemental analysis, thermogravimetric analysis, and a luminescence study. The solids of <b>1</b>-<b>3</b> exhibited intense photoluminescent emission with λ_em^max at ca. 493, 472, and 500 nm, respectively. Remarkably, due to their excellent framework stability, <b>1</b> and <b>2</b> can act as multiresponsive luminescent sensors for nitrobenzene, Fe³⁺, and Cr₂O₇^2- with a high selectivity and sensitivity ascribed to their quenching effect.