Mechanistic investigation of photocatalytic degradation of organic dyes by a novel zinc coordination polymer

Abstract

A new coordination polymer {[Zn(TIPA)(seb)_0.5](NO₃)·3.5H₂O}_n (1) (TIPA = tris(4-(1H-imidazol-1-yl)phenyl)amine, seb = sebacic acid) is prepared and characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD) and single crystal X-ray diffraction. Complex 1 has a three-dimensional (3D) 2-fold interpenetrating diamondoid network, and can be represented by the Schläfli symbol {3³·4³·5⁴·6⁴·7}. The luminescent, optical, and thermal properties of 1 in the solid state are investigated. Significantly, 1 assists in the photo-degradation of organic dyes in the presence of H₂O₂ and upon irradiation with UV light (λ = 254 nm). A mechanistic study toward understanding the photocatalytic degradation of organic dye molecules is carried out. The study reveals that the band gap of the fluorophore TIPA is lowered by the charge interaction between the Zn²⁺ cation and ligand seb²⁻ dianion. The enhanced photocatalysis of 1 is also accompanied by the selective sensing of polar organic solvent nitromethane (NM) and antibiotic ofloxacin (OFX) by a luminescence quenching process. Concurrently, 1 demonstrates excellent ability to adsorb inorganic pollutant permanganate ions likely due to the presence of its unique 3D structural network.