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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 29, Number 6
BKCSDE 29(6)
June 20, 2008 

 
Title
The Studies on Molecular Geometries and Electronic Structures of Substituted meso-Catecholic Porphyrins: DFT Methods and NSD
Author
Seung Hyun Park, Su Jin Kim, Jin Dong Kim, Sung-Bae Park, Do Sung Huh, Yong Key Shim, Sang Joon Choe*
Keywords
meso-Catecholic porphyrins, Photodynamic therapy (PDT), DFT
Abstract
Geometry optimizations and electronic structure calculations are reported for meso-tetraphenyl porphyrin (TPP) and a series of meso-substituted catecholic porphyrins (KP99150, KP99151, KP99152, KP99153, and KP99090) using density functional theory (DFT). The calculated B3LYP//RHF bond lengths are slightly longer than those of LSDA//RHF. The calculated electronic structures clearly show that TPP and meso-catecholic group contribute to π-electron conjugation along porphyrin ring for HOMO and LUMO, significantly reduced the HOMO-LUMO gap. The wavelength due to B3LYP energy gaps is favored with experimental value in Soret (B), and LSDA energy gaps are favored with experimental value in visible bands (Q). The electronic effect of the catecholic groups is to reduced energies of both the HOMOs and LUMOs. However, the distortion of porphyrin predominantly raises the energies of the HOMOs, so the net result is a large drop in HOMO and smaller drop in LUMO energies upon meso-substituted catecholic group of the porphyrin macrocycle as shown in KP99151 and KP99152 of Figure 5(a). These results are in reasonable agreement with normal-coordinate structural decomposition (NSD) results. The HOMO-LUMO gap is an important factor to consider in the development of photodynamic therapy (PDT).
Page
1141 - 1148
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