Intrinsic structural features of coordination polymers make an impact on dye selectivity

Abstract

Five dicarboxylate coordination polymers having 1-phenyl-3-((pyridin-4-yl)methyl)urea (L) as co-ligands with general formula [M₂L₂(dicarb)(H₂O)₂]_n (dicarb = succinate or fumarate for M = Co and Zn; terephthalate for M = Co) were synthesised and characterised. Analysis of the supramolecular features of self-assemblies revealed that the hydrogen bonds of coordinated water and urea significantly contributed to the self-assemblies. The C–H⋯π interactions in certain self-assemblies locked the phenyl ring of the urea moiety. These interactions influenced intermolecular hydrogen bonds in those self-assemblies to distinguish them through characteristic hydrogen bonds. The free N–H bonds from the urea part exposed outward from the chain-like arrangements of the cobalt terephthalate coordination polymer enabled it to selectively adsorb methyl orange dye over phenol red dye. The zinc succinate as well as fumarate coordination polymers were fluorescent and showed dual emissions.