Syntheses, structures and anion exchange properties of accommodative silver chains using a positively charged and flexible ligand

Abstract

Eight silver(I) coordination polymers were synthesized and structurally characterized. Direct reaction of various Ag(I) starting materials with a positively charged and flexible ligand, 1,3-di(2-picolyl)imidazolium (L) in different salts, including L-Cl, L-ClO4 and L-PF6, gave compounds [AgL(NO3)2] (1), [AgL(CH3CN)](BF4)2 (2), [Ag2L2(NO3)2](NO3)Cl (3), [AgL(CH3CN)](PF6)2·0.5CH3CN (4), [AgL(NO3)](PF6) (5), [AgL](NO3)(PF6) (6), [AgL(CH3CN)2](ClO4)(PF6)·CH3CN (7), and [AgL](ClO4)2·CH3CN (8). Structural analysis revealed that ligand L has three kinds of conformations in these structures. As benefited by the flexible feature of L, the silver chains in 1–8 are different and are depended on the shape and the size of counter anions. Anion exchange studies showed that crystals of 4, 6 and 8 had anion exchange properties, and the channel size in the corresponding solid state structures played a crucial role. These results highlighted the significance of positively charged and flexible ligand L in the construction of various silver chain structures with different conformations and thus packing diagrams for anion exchange studies.