Perchlorate-supported Cu(ii)-based 1D polymeric chains containing 1,10-phenanthroline: synthesis, characterization and adsorption of organic dyes and heavy metal ions

Abstract

A one-dimensional (1D) copper(II) polymeric chain, [Cu(1,10-phen)(ClO₄)(H₂O)₂]_n (1), was synthesized by reacting Cu(ClO₄)₂·6H₂O with 1,10-phenanthroline in the presence of triethylamine in methanol. X-ray crystallography revealed that 1,10-phenanthroline acted as a bidentate ligand, while ClO₄⁻ served as a perchlorate-bridged linker, generating a 1D-polymeric chain. Adsorption studies were conducted for 1 against methylene blue (MB), methyl orange (MO) and heavy metal ions such as copper (Cu²⁺) and cadmium (Cd²⁺). In the case of MB, the maximum adsorption efficiency by adsorbent 1 was interpreted to be the highest (85.13%) at pH 3; however, for MO, it was 68.10%, and in the case of heavy metals, the maximum adsorption capacity was recorded for Cd (52.20%), in contrast to Cu (34.87%). The adsorption mechanism was rationalized by the fact that the dye molecules, equipped with aromatic moieties, interacted with 1 through electrostatic interactions, π⋯π interactions and OH⋯π interactions. However, with reference to heavy metals, 1 primarily exhibited electrostatic interactions with the metal ions (Cd²⁺ and Cu²⁺). The adsorption behavior of MB and MO significantly corroborated the pseudo-second-order kinetics, which indicated chemisorption as the main mechanism.