FTIR, magnetic, 1H NMR spectral and thermal studies of some chelates of caproic acid: Inhibitory effect on different kinds of bacteria

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 70; no. 1; pp. 217 - 233
• Main Authors: Refat, Moamen S., El-Korashy, Sabry A., Kumar, Deo Nandan, Ahmed, Ahmed S.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.06.2008
• Subjects: 1H NMR spectra; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Calibration; Caproates - chemistry; Caproates - metabolism; Caproic acid; Cations, Divalent; Chelating Agents - chemical synthesis; Chelating Agents - chemistry; Chelating Agents - metabolism; Chelating Agents - pharmacology; Gram-Negative Bacteria - drug effects; Gram-Positive Bacteria - drug effects; Infrared spectra; Kinetics; Magnetic Resonance Spectroscopy - methods; Magnetics; Metals, Heavy - chemistry; Metals, Heavy - pharmacology; Microbial Sensitivity Tests; Models, Chemical; Molecular Structure; Spectrophotometry, Ultraviolet - methods; Spectroscopy, Fourier Transform Infrared - methods; Temperature; Thermodynamic paramenters; Thermogravimetry; 1H NMR spectra; Antibacterial activity; Infrared spectra; Caproic acid; Thermodynamic paramenters
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2007.07.036

A convenient method for the preparation of complexes of the Cr 3+, Mn 2+, Fe 3+, Co 2+, Ni 2+, Zn 2+, ZrO 2+, UO 2 2+, Zr 4+ and Th 4+ ions with caproic acid (Hcap) is reported and this has enabled 10 complexes of caproate anion to be formulated: [Cr(cap) 3]·5H 2O, [Mn(cap) 2(H 2O) 2], [Fe(cap) 3]·12H 2O, [Co(cap) 2(H 2O) 2]·4H 2O, [Ni(cap) 2(H 2O) 2]·3H 2O, [Zn(cap) 2], [ZrO(cap) 2]·3H 2O, [UO 2(cap)(NO 3)], [Zr(cap) 2(Cl) 2] and [Th(cap) 4]. These new complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, 1H NMR and UV–vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. It has been found from the elemental analysis as well as thermal studies that the caproate ligand behaves as bidentate ligand and forming chelates with 1:1 (metal:ligand) stoichiometry for UO 2 2+, 1:2 for (Mn 2+, Co 2+, Ni 2+, Zn 2+, ZrO 2+ and Zr 4+), 1:3 stoichiometry for (Cr 3+ and Fe 3+) and 1:4 for Th 4+ caproate complexes, respectively, as bidentate chelating. The molar conductance measurements proved that the caproate complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E*, Δ H*, Δ S* and Δ G* are estimated from the DTG curves. The antibacterial activity of the caproic acid and their complexes was evaluated against some gram positive/negative bacteria.