24315-65-9Relevant academic research and scientific papers
KINETICS OF COMPLEX FORMATION BETWEEN ZINC MESO-TETRAPHENYLPORPHYRIN AND SOME NITROGEN BASES IN APROTIC SOLVENTS, STUDIED BY AN IMPROVED MICROWAVE TEMPERATURE-JUMP METHOD
Caldin, Edward F.,Field, John P.
, p. 1923 - 1936 (1982)
Rate and equilibrium constants have been determined over a range temperature for the reactions of zinc meso-tetraphenylporphyrin with pyridine (in chlorobenzene, 1-chlorobutane and toluene), with 2-methylpyridine (in 1-chlorobutane), and with imidazole (in 1-chlorobutane).Rates were measured by means of an improved microwave temperature-jump apparatus incorporating signal-averaging, and at low temperatures by the stopped-flow method, with spectrophotometric detection.The forward rate constants are lower by about an order of magnitude than the values calculated for diffusion control from the simple Smoluchowsky model.A two-step mechanis appears likely.Solvent and steric effects on the rate are discussed.
Magnetic circular dichroism spectroscopy of zinc(II) tetraphenylporphyrin-ligand complexes: the effect of the axial ligand on spectral properties
Kintner, Elisabeth T.,Nardo, Joseph V.,Dawson, John H.
, p. 493 - 508 (2007/10/02)
The magnetic circular dichroism (MCD) spectra in the UV-visible spectral region (300-700 nm) of an extensive set of zinc tetraphenylporhyrin (ZnTPP) complexes with oxygen, nitrogen and sulfur donor axial ligands are reported.Because zinc porphyrins do not
Reactions of metalloporphyrin π radicals. 1. Complexation of zinc tetraphenylporphyrin cation and anion radicals with nitrogenous bases
Kadish,Shiue,Rhodes,Bottomley
, p. 1274 - 1277 (2008/10/08)
Stability constants for TPPZn with 20 nitrogenous bases were obtained by the method of proportional absorbances. These results were combined with electrochemical data to obtain stability constants for the reaction of TPPZn radical cations and radical anions with ligands. Values of log β1 ranged from 1.64 to 4.59 for ligand addition to [TPPZn]+ and from 1.47 to 3.50 for addition to [TPPZn]-. Only five-coordinate complexes were observed. These measurements represented the first values of stability constants obtained for nitrogeneous base addition to porphyrin π radicals. The changes in stability constants observed as a function of ligand pKa allowed the tuning of the zinc radical cation half-wave potential between 0.83 and 0.74 (vs. SCE) and the radical anion potential between -1.38 and -1.49 V. The ligand additions proceeded in a chemically reversible fashion over the experimental time frame. Thin-layer spectra for oxidations showed slight spectral differences between [TPPZn]+ and [TPPZn(L)]+ but were almost totally insensitive to a specific L. The possibility of an alternate oxidative pathway to the β-substituted pyrrole product was examined and found not to be operative for this time frame and solvent system.
