New heteroleptic Cu(II) complexes of chrysin with 2,2-bipyridine and substituted 1,10-phenanthrolines: Synthesis, characterization, thermal stability and antioxidant activity

In this study, the new heteroleptic Cu(II) complexes of chrysin were synthesized by using 2,2 -bipyridine and substituted 1,10-phenanthroline (1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline or bathophenanthroline) co-ligands. The characterization of the obtained heteroleptic Cu(II) complexes were carried out by elemental analysis, ESI-MS, UV-visible and infrared spectral analyses, thermal analysis, magnetic susceptibility and molar conductivity measurements. In these complexes, chrysin, 2,2 - bipyridine, or substituted 1,10-phenanthrolines and Cu(II) ion were found in a ratio of 1: 1: 1. In addition, the resulting data supported square plane geometry for Cu(II) complexes. According to the results obtained, the proposed compositions are as follows: [Cu(chrH-1)(bPY)]ClO4 center dot H2O (1, chrH = chrysin, bpy = 2,2'-bipyridine), [Cu(chrH-1)(phen)]ClO4 center dot 1.5H(2)O (2, phen = 1,10 - phenanthroline), [Cu(chrH-1)(dmphen)]ClO4 (3, dmphen = 4,7-dimethyl-1,10-phenanthroline) and [Cu(chrH-1)(Bphen)]ClO4 (4, Bphen = Bathophenanthroline). Total phenolic contents and antioxidant capacities of Complexes 1-4 were measured by the Folin-Ciocalteu and ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) methods, respectively. According to the results, Complex 4 has the highest antioxidant capacity. (C) 2020 Elsevier B.V. All rights reserved.