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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 

 
Title
Kinetics of the Formation of Metalloporphyrins and the Catalytic Effect of Lead Ions and Hydrogen Ions
Author
Yong Qi, Ji Gang Pan*
Keywords
5,10,15,20-Tetrakis(4-isopropylphenyl)porphyrin (TIPP), Metalloporphyrin, Catalysis, Kinetics, UV/Vis-spectra
Abstract
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.
Page
3313 - 3318
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