A protonated imine-based water-soluble cadmium complex with N, O donor chelating agent: Synthesis, structure, fluorescence efficiency and catecholase activity

• Published in: Journal of molecular structure 2024-07, Vol.1308, p.138093, Article 138093
• Main Authors: Haldar, Anwesha, Mandal, Bikramaditya, Rakshit, Trilochan, Mandal, Debdas, Ganguly, Rakesh
• Format: Article
• Language: English
• Subjects: Catecholase activity; Luminescent properties; Water-soluble Cd(II) complex; X-ray structure; Zwitterionic form
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.138093

A mononuclear air-stable and water soluble six coordinated cadmium (II) complex [Cd(HL)6](ClO4)2 (1) with bi-dentate phenol based ligand [HL = 2-(benzylimino)methyl)phenol] have been synthesized. The complex has been characterized by various spectroscopic techniques. The solid-state structure, by single crystal X-ray diffraction, revealed that Cd(II) complex crystallizes in trigonal space group R-3. Interestingly, single crystal X-ray structure data show that the Schiff base in the complex is present in a zwitterionic form and coordinated through the phenolic oxygen atom only, providing the first example of more than four monodendate Schiff base in zwitterionic form to be coordinated with the central metal ion. Cyclic voltamogram of the cadmium (II) complex (1) exhibits a quasi-reversible oxidation peak in the positive potential region. The redox process occurs due to the generation of phenoxyl radical from the pheolate group of the attached ligand with the central metal ion. Luminescence spectra show a strong emission band around 500 nm. Additionally, the mononuclear cadmium complex (1) shows catechol oxidase activity in methanol under aerobic conditions. The turnover number of the process is 2.766 × 103 h–1. The oxidation process occurs via formation of ligand oriented phenoxyl radical species.