Spectrophotometric and thermodynamic study on reaction of tetra (p-sulphnaphthyl) porphyrin Iron (II) complex with thiols and glycine ethyl ester as amodel for cytochrome (p-450) state c and haemochrome.


Studies using spectrophotometric titrations on dilute solution of tetra (p-sulphonaphthyl) porphinato Iron (II) [ TNPS4 Fe (II) ] in the presence of a large excess of thiols and glycine ethyl ester at high (PH=12.8) are reported. evidence for high spin five coordinate Iron (II) and low spin six coordinate Iron (II) complexes were found . Thermodynamic parameters and stability constants were also recorded , refer to exothermic reaction with negative values of ∆H and ∆G for both ligands thiols and glycine ethyl ester . LogKF , Log KD and (n) number of bounded ligands were calculated , to be found for (n=1-1.3) for thiol ligand and (n=1.8-2.1) for glycine ethyl ester ligand , which were assigned to five and six coordinate to the Iron (II) atom , respectively. These results are discussed in relation to the high spin Iron (II) state in the catalytic cycle of cytochrome (p-450) and to the low spin Iron (II) haemochrome.