Synthesis, structural characterization and antimicrobial activity evaluation of metal complexes of sparfloxacin

The synthesis and characterization of binary Cu(II)- (1), Co(II)- (2), Ni(II)- (3), Mn(II)- (4), Cr(III)- (5), Fe(III)- (6), La(III)- (7), UO2(VI)- (8) complexes with sparfloxacin (HL1) and ternary Cu(II)- (9), Co(II)- (10), Ni(II)- (11), Mn(II)- (12), Cr(III)- (13), Fe(III)- (14), La(III)- (15), UO2(VI)- (16) complexes with sparfloxacin (HL1) and dl-alanine (H2L2) complexes are reported using elemental analysis, molar conductance, magnetic susceptibility, IR, UV–Vis, thermal analysis and 1H-NMR spectral studies.The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature.All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Cu(II) complexes which were four coordinate, square planar and U- and La-atoms in the uranyl and lanthanide have a pentagonal bipyramidal coordination sphere. The antimicrobial activity of these complexes has been screened against two Gram-positive and two Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with reference drug sparfloxacin. All the binary and ternary complexes showed remarkable potential antimicrobial activity higher than the recommended standard agents. Ni(II)- and Mn(II) complexes exhibited higher potency as compared to the parent drug against Gram-negative bacteria.

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► Binary and ternary complexes of sparfloxacin with dl-alanine are reported.
► Physicochemical and spectral methods have been used.
► Sparfloxacin coordinates through pyridone and carboxylate oxygen.
► dl-alanine coordinates through the deprotonated carboxylate-O and amino-N.
► High antimicrobial activity is recorded.