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Adjacent versus opposite type di-aromatic ring-fused phthalocyanine derivatives: synthesis, spectroscopy, electrochemistry, and molecular orbital calculations.
MedLine Citation:
PMID:  12095345     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
A series of adjacent and opposite type di-aromatic ring-fused phthalocyanines (Pc's) of varying size have been prepared and characterized spectroscopically and electrochemically, and most of their properties have been reasonably reproduced by molecular orbital (MO) calculations. The adjacent isomers alone were obtained preferentially by using a diphthalonitrile unit linked via a short aryl chain. The main results are summarized as follows. (i) The Q-band shifts to longer wavelength and its intensity increases, but the degree of change decreases, with increasing molecular size. On the bases of the experiments and MO calculations, setting the size of the effect of benzene directly fused to the tetraazaporphyrin (TAP) skeleton at unity, the effect of the second and third benzene units is roughly about 0.75-0.80 and 0.48 +/- 0.06, respectively. As a result of this, among compounds having an isomeric pi-system, the Q-band of a D(4h) type species lies at longer wavelength than those of adjacently and oppositely di-aromatic ring-fused species. (ii) The Q-band of adjacently substituted species does not split appreciably, while that of the oppositely substituted species splits substantially, the extent having a parallel relationship with the ratio of long to short axes in the molecule. In general, the larger the ratio, the larger the splitting. (iii) The Q-band of oppositely dibenzo-fused and bis(dialkyl)-substituted TAP does not show explicit splitting because of the large coefficients of the carbons substituted with alkyl groups in the MOs. (iv) Interestingly, the first oxidation in adjacently and oppositely dibenzo-fused CoTAP occurs at the cobalt and ligand, respectively, although they are isomers to each other.
Authors:
Nagao Kobayashi; Hideya Miwa; Victor N Nemykin
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  124     ISSN:  0002-7863     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2002 Jul 
Date Detail:
Created Date:  2002-07-03     Completed Date:  2002-08-20     Revised Date:  2003-11-03    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8007-20     Citation Subset:  -    
Affiliation:
Contribution from the Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
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