Hydrothermal synthesis and characterization of a series of luminescent Ag() coordination polymers with two new multidentate bis-(1,2,3-triazole) ligands: structural diversity, polymorphism and photoluminescent sensing

In this work, two new multidentate bis-(1,2,3-triazole) ligands 1-(4-(2 H -1,2,3-triazol-2-yl)butyl)-1 H -1,2,3-triazole (L 1 ) and 1,6-bis(2 H -1,2,3-triazol-2-yl)hexane (L 2 ) have been designed and synthesized. Under hydrothermal conditions, a series of luminescent Ag( i ) coordination polymers, namely, {[Ag(L 1 ) 2 ](PF 6 )} n ( 1 ), {[Ag 2 (L 1 ) 2 (bbtr)](BF 4 ) 2 } n ( 2 ), {[Ag 2 (L 1 ) 2 (bbtr)](BF 4 ) 2 } n ( 3 ), {[Ag 2 (L 1 ) 2 (bbtr)](PF 6 ) 2 } n ( 4 ) and [Ag 2 (L 2 )(NO 3 ) 2 ] n ( 5 ) (bbtr = 1,4-di(1,2,3-triazol-1-yl)butane) can be isolated. For 1 , bidentate L 1 ligands bridge neighboring Ag( i ) ions, forming a 1D tubular framework. Further, when L 1 and bbtr are used to react with AgBF 4 , two scarcely reported mixed-ligand polymorphic cluster-based Ag I frameworks, 2 (1D) and 3 (2D), can be isolated under different reaction temperatures. Further, free BF 4 anions within the crystalline framework of 2 can be exchanged with PF 6 anions to generate the anion exchanged crystalline product {[Ag 2 (L 1 ) 2 (bbtr)](PF 6 ) 2 } n ( 4 ) in a single-crystal-to-single-crystal (SCSC) manner. For 5 , tetradentate L 2 ligands bridge neighboring Ag I centers, leading to a 3D coordination polymer. The solid state luminescence properties of 15 have been investigated, indicating strong fluorescent emissions. Additionally, luminescence measurements illustrate that complex 5 exhibits highly selective and sensitive luminescence sensing of Cr 2 O 7 2 ions in aqueous solutions with high quenching efficiency ( K sv = 1.53 10 4 L mol 1 ) and low detection limit (0.23 M (S/N = 3)), which make it a promising candidate for sensing Cr 2 O 7 2 anion pollutants in the actual measurement process. 5 is the first coordination polymer based on a bis-(1,2,3-triazole) derivative as luminescent probes of Cr 2 O 7 2 ions in aqueous solutions. In this work, a series of luminescent Ag( i ) coordination polymers with two new bis-(1,2,3-triazole) ligands have been prepared and characterized.