Ligand binding to metalloporphyrins. 1. Thermodynamic constants for the association of imidazole with tetraphenylporphyrin iron (III) chloride in acetone

✍ Scribed by James M. Duclos

• Book ID: 104106011
• Publisher: Elsevier Science
• Year: 1973
• Weight: 679 KB
• Volume: 2
• Category: Article
• ISSN: 0006-3061
• DOI: 10.1016/s0006-3061(00)80254-9

✦ Synopsis

The interaction between imidazole and tetraphenylporphyriniro;ron(III) in acetone has been studied by following the formation of the bti-imidazole tetraphenyIporphyri&n(Ill) e~mpley at MQ nm. The number of spectraactive species at this waveiength is shown to be two: ~uncomplered tetraphenylporphyriniron(III) and the his-imidazole complex. Thermdynamic parameters have been determined; for the equilibrium, FeTPPCi +2Imz= FeTPP*Imz+ + Cl-, AHo = -19.79 f 0.01 kcal/mol, AFspl = -44 3~ 4 eu, and A@?s,u.z = -6.6 f 0.1 kcal/mol. preliminary results comparing the solvent effect on this equilibrium are reported.