Designing of emerald terbium (III) ions with β-ketocarboxylic acid and heterocyclic ancillary ligands for biological and optoelectronic applications.

A green and highly efficient grinding method was adopted to synthesize emerald terbium complexes with 1-cyclopropyl-6-fluro-4-oxo-7-piperazin-1-ylquinoline-3-carboxylic acid as main organic ligand and 2,2'-bipyridyl, 1,10-phenanthroline, neocuproine, 5,6-dimethyl-1,10- phenanthroline and bathophenanthroline as ancillary ligands. Structural analysis of these complexes was executed via elemental, infrared and 1 H-NMR analysis, which confirmed that the ligand coordinated to the metal ion through β-ketone and hydroxyl group of carboxylic acid respectively. Thermal stability of these complexes was investigated by study of thermogravimetric analysis (TG/DTG). Photoluminescence properties were investigated by observing emission spectra (400-700 nm), excitation spectra (250-500 nm) and decay time curves for display devices. The emission spectra reveal that an intense peak at 545 nm was observed due to 5 D4 →7 F5 electronic transition, which is responsible for emerald color in synthesized complexes, under 353 nm UV-excitation. The energy band gap and refractive index were determined, which proclaimed the dormant applications of these complexes in semiconductors. CIE color coordinates confirmed that the emerald emission of these complexes lies in green region. Further, the antioxidant, antimicrobial and antimalarial assays of these complexes were also investigated, which confirms that these complexes are potent for antioxidant, antimicrobial and anti-malarial activities. This article is protected by copyright. All rights reserved.