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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 35, Number 11
BKCSDE 35(11)
November 20, 2014 

Kinetics of the Formation of Metalloporphyrins and the Catalytic Effect of Lead Ions and Hydrogen Ions
Yong Qi, Ji Gang Pan*
5,10,15,20-Tetrakis(4-isopropylphenyl)porphyrin (TIPP), Metalloporphyrin, Catalysis, Kinetics, UV/Vis-spectra
The reaction mechanism of Lead ions catalyzing complexation reactions between TIPP and metal ions was investigated by researching the kinetics of the formation of metalloporphyrins by UV/Vis-spectra, and verified by exploring the formation of metalloporphyrins catalyzed by acetic acid. Kinetics studies suggested that the fluctuations of reaction rate indicated the formation of metalloporphyrin was step-wise, including the preequilibrium step (the coordination of the pyrrolenine nitrogens to Mn+) and the rate-controlling step (the deprotonation of the pyrrole proton). In the pre-equalization step, a sitting-atop (SAT) structure formed first with the complexation between larger radius of Pb2+ and TIPP, changed the activation, then Pb2+ left with the smaller radius of metal ions attacking from the back of the porphyrin ring center. In the rate-controlling step, two pyrrole protons dissociated to restore a stable structure. This was verified by adding acetic acid at different reaction times.
3313 - 3318
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