2D and 3D Ag(I) coordination polymers with a 2-methylimidazole substituted cyclotriphosphazene ligand: Structures and dye adsorption properties

Abstract

Coordination polymers are a promising crystalline framework for dye capture and separation in recent years. We are reporting herein the two new, Ag(I) coordination polymers, namely {[Ag3(MeIm-Cp)2](NO3)3}n (1) and {[Ag(MeIm-Cp)](CH3PhSO3)} (2), were synthesized from hexapodal-shaped 2-methylimidazole substituted cyclotriphosphazene, (MeIm-Cp). MeIm-Cp was characterised by 1H NMR, 31P NMR and mass analysis. Structure of each isolated compounds were assigned by single crystal X-ray crystallography. In complex 1, MeIm-Cp has a κ6N coordination mode by connecting six Ag(I) ions to constitute a 3D coordination framework whereas the ligand in complex 2 displays κ4N coordination mode via linking four Ag(I) ions together to create a 2D coordination polymer. Topologically, coordination polymer 1 exhibits a 4,4,6-connected three nodal net with point symbol {44.62}3{46.68.8}2, while coordination polymer 2 displays a four-connected network having the point symbol {43.63}. According to thermogravimetric analysis, the thermal stability of MeIm-Cp is higher than complexes. The synthesized coordination polymers were used for the adsorption of some cationic and anionic organic dyes in aqueous media, Dye adsorption studies were performed out using UV–Vis. absorption spectroscopy. Adsorption experiments show that complex 1 removes the anionic methyl orange (MO) and tartrazine (E102) from water but shows no adsorption behaviour toward the cationic methylene blue (MB).