A vic -dioxime ligand bearing fluorescent coumarin moieties and its complexes; preparation, spectroscopy, and electrochemistry

• Published in: Journal of coordination chemistry 2008-04, Vol.61 (8), p.1172-1183
• Main Authors: Esenpinar, A. Asli, Kandaz, Mehmet, Özkaya, Alİ Riza, Bulut, Mustafa, Güney, Orhan
• Format: Article
• Language: English
• Subjects: Cobalt; Copper; Coumarin; Cyclic voltammetry; Fluorescence; Nickel; Uranyl; Vic-dioxime complexes
• ISSN: 0095-8972; 1029-0389
• DOI: 10.1080/00958970701502342

The synthesis of a new vic-dioxime ligand, N,N′ 2 -dihydroxy-O 1 ,O 2 -bis(4-methyl-2-oxo-2H-chromen-7-yl)oxalimidamid (LH 2 ) (1), bearing functional coumarins and its soluble mono- {Ni(II), Cu(II), Co(II)} and dinuclear {UO 2 (II)} complexes are presented. The fluorescence properties due to the 7-hydroxy-4-methylcoumarin fluorophore, which is conjugated with vic-dioxime that functions as the MN 4 core of 1 and its complexes, are also reported. The formation of coordination complexes resulted in the blue shift in excitation spectrum and fluorescence quenching of 1. Both mononuclear {(LH) 2 M, M=Ni(II), Cu(II), and Co(II)} and homodinuclear {(LH) 2 (UO 2 ) 2 (OH) 2 )} complexes have been obtained with metal : ligand ratios of 1 : 2 and 2 : 2, respectively. The characterizations of the new compounds were made by elemental analysis, 1 H-NMR, FT-IR, UV-Vis, and LCMS data. Redox behavior of 1, involving oxime and coumarin moieties, and its complexes with Ni(II), Cu(II), Co(II) and UO 2 (II) were investigated by cyclic voltammetry. The comparison of the electrochemical behavior of 1 with its complexes enabled us to identify metal-, oxime- and coumarin-based signals.