Sunlight Irradiation Reactions of Methoxylated Dibenzylideneacetone with Group 6 and 8 Metal Carbonyl Complexes: Synthesis, Characterization, Spectral Investigation and Biological Activities

Abstract

Sunlight irradiation of the reactions of either [M(CO) 6 ], M = Cr, Mo and W or [M 3 (CO) 12 ], M = Ru or Os with methoxylated dibenzylideneacetone; 1,5-bis(3,4methoxyphenyl)-penta-(1E,4E)-1,4-dien-3-one (mdba) in benzene were investigated. While a mononuclear oxo-chromium complex with molecular formula [CrO(mdba-H) 2 ], 2 was obtained, two dinuclear complexes with molecular formulas [Mo 2 O 2 (mdba-H) 2 ], 3, [W 2 O 4 (mdba-H) 2 ], 4, were isolated. The corresponding photochemical reactions of mdba with group 8 cluster complexes produced the complexes, [Ru 3 (CO) 6 (mdba-H) 2 ], 5, and [Os 3 (CO) 6-(mdba-H) 2 ], 6, with one Ru-Ru bond breaking. The organic ligand in complexes realizes different coordination modes. With group 6 metal carbonyls, the ligand behaves as bidentate where it coordinate to the metal through keto group and a carbon from ethylene group after loss of one proton forming five-membered ring. On other hand, with group 8 metal carbonyls the olefin bond of the ligand participate in coordination in addition to the coordination through keto group and a carbon of ethylene group with loss of one proton. All complexes were characterized by elemental analysis, infrared, mass, ESR, 1 H NMR and 13 C-NMR spectroscopy. The UV-vis spectra of the complexes showed shift in the visible band of the ligand due to coordination. Thermal properties of the complexes were investigated by TG thermogravimetry technique. The synthesized mdba ligand and its complexes were screened for their antibacterial activity against two gram positive bacteria, two gram negative bacteria and fungi candida albicans. The activity was compared with standard Amikacin.