Coordination susceptibilities of cinnamaldehyde and cuminaldehyde derived Schiff bases towards the &ITfac&IT-[Re(CO)3]+ core: Formation, computational and DNA interaction studies

Herein, we explore the coordination behaviours of Schiff bases derived from constituents of essential oils (viz. cinnamaldehyde and cuminaldehyde) and aromatic amines (viz 2-aminophenol and 4-aminoantipyrene) towards the facial tricarbonylrhenium(I) core. The resultant rhenium(I) compounds: (mu-X)(2)[Re(CO)(3)](2) {where X = 2{[3-Phenylprop-2-en-1-ylidene]amino}phenol (ciap) (for 1) or 2-{[4-(propan-2-yl)benzylidene]amino}phenol (cuap) (for 2), fac-[Re(CO)(3)(apy)Cl] (apy = 4-aminoantipyrene) (3) and fac-[Re(CO)(3)(cinap)Cl] (cinap = 1,5-dimethyl-2-phenyl-4-{[3-phenylprop-2-en-1-ylidene]amino}-1,2-dihydro-3H-pyrazol-3-one) (4) were formed. The metal compounds were spectroscopically characterized and structural elucidations were confirmed by single crystal X-ray diffraction. DFT studies were utilized to rationalize the contrasting coordination behaviours of the structural analogues, 1,5-dimethyl-2-phenyl-4-{[4-(propan-2-yl)benzylidene]amino}-1,2-dihydro-3H-pyrazol-3-one (cumap) and cinap in the formation of 3 and 4, respectively. These metal compounds showed affinities towards Calf-Thymus DNA based on UV-Vis DNA binding titrations and molecular docking studies revealed that they are groove binders. In addition, gel electrophoresis experiments indicated that steric factors has an influence on the DNA cleavage activities of the mono- and dinuclear rhenium(I) compounds. (C) 2018 Elsevier B.V. All rights reserved.