Structural, morphological and biological investigations of some transition metal-5-Fluorouracil-amino acid mixed ligand complexes

Mixed ligand complexes (1a-1c) of type MAB (where M = Ni(II)/Cu(II)/Zn(II); A = 5-FU; B = phe) were isolated in their solid state and characterized by various physico-chemical and spectral techniques. Thermal studies (TG/DTA) on the synthesized mixed ligand complexes (1a-1c) show an initial loss of coordinated water molecule followed by decomposition of the organic residue. XRD and SEM analyses suggest the microcrystalline and homogeneous morphology for MAB complexes. The in vitro antimicrobial, antioxidant, nuclease cleavage and binding interactions of the free ligand(A) and its mixed ligand systems were studied. Further, the 3D molecular modeling and analysis of Cu(II)-5-FU(A)-phe(B) mixed ligand complex has been undertaken. In addition, the complex formation equilibria were also studied pH-metrically in aqueous medium (I = 0.15 M) for Cu(II) ion with 5-Fluorouracil (5-FU; A) and some bioactive amino acid ligands(B) viz., glycine(gly), L-alanine(ala), L-valine(val) and L-phenylalanine(phe). The calculated stabilization parameters Delta logK, logX, logX' and % R.S. indicate that mixed ligand systems have higher stabilities than their binary counterparts. Thermodynamic parameters (Delta(double dagger)G, Delta H-double dagger and Delta S-double dagger) have also been determined from the stability constants at 300, 310, 320 and 330 +/- 0.1 K. The complexation behavior has been studied by means of spectrophotometry at different pH. The biological studies of the mixed ligand systems show moderate activities. (C) 2015 Elsevier B.V. All rights reserved.