Abstract

SYNTHESIS, COMPARATIVE STUDIES ON THE CHARACTERIZATION AND BIOLOGICAL ACTIVITY OF CHLOROCHROMIUM(III) AND CHLORO-OXO-CHROMIUM(V) PORPHYRINS

Gauri D. Bajju*, Ved Kumar and Ashu

Abstract

The six co-ordinated Chlorochromium(III) and Chloro-oxochromium( V) complexes of general formula [CrCl(XTPP)L] and [Cr(O)(Cl)(XTPP)] where X = CH3, OCH3 and Cl groups and L = 2- ethyl pyridine, 3-ethylpyridne, 4-ethylpyridine and 3,4- dimethylpyridine were prepared by reacting the ligands with [CrCl(XTPP)]. The six co-ordinated complexes [Cr(O)(Cl)(XTPP)] were prepared by treating the chlorochromium(III) porphyrin with Iodosylbenzene in methylene chloride at room temperature. The complexes so obtained were characterized by elemental analysis, UVvisible, I.R, 1H NMR and mass spectroscopy. In Chlorochromium(III) porphyrins the vibrational frequency due to Cr-N appears at 430-495 cm-1 and bands appearing in range of 370-430 cm-1 are attributed due to (Cr-Cl) vibrations. The presence of two band occurring between 300-610 nm gives the presence of Cr(III) porphyrin with 3d3 configuration whereas chromium (V) porphyrins shows hypsochromic shift compared to Chromium(III) porphyrins. When oxidation state changes from +3 to +5 for Chloro-oxochromium (V) the O=Cr(V)(Cl)TPP the soret band appears at 415 nm. The hypsochromic (blue) shift in Oxochromium(V) confirms the d1configuration for Cr(V) relative to respective Chlorochromium(III) porphyrins with 3d3 configuration is due to presence of electron attracting oxo-group axially attached to the Cr(V) ion. The presence of Oxochromium(V) is attributed due to O=Cr stretching frequency in the range of 900-1100 cm-1 which in [Cr(O)(Cl)TPP] appears at 1026 cm-1 for (Cr = 0) stretch. The spectroscopic and magnetic studies provides the information for the octahedral configuration geometry to these complexes. Biologically the Chlorochromium(III) complexes shows the +ve antifungal activity but –ve antibacterial and antioxidant behavior whereas Oxochromium(V) porphyrins shows enhanced antifungal, antibacterial and antioxidant action. The enhanced antibacterial and antifungal activity may be attributed due to introduction of Oxo ligand at sixth position relative to pyridines in Chlorochromium(III) porphyrins. The complexes when tested for acute toxicity in mice do not show any hazardous symptoms or deaths and thus have low toxicity potential and relatively high safety margins.

Keywords: Comparative octahedral chlorochromium(III) and Chloro-oxo-chromium(V) porphyrins. Biological activity acute oral toxicity.