Adjacent versus opposite type di-aromatic ring-fused phthalocyanine derivatives: Synthesis, spectroscopy, electrochemistry, and molecular orbital calculations

Nagao Kobayashi, Hideya Miwa, Victor N. Nemykin

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101 Citations (Scopus)

Abstract

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 π-system, the Q-band of a D4h 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.

Original languageEnglish
Pages (from-to)8007-8020
Number of pages14
JournalJournal of the American Chemical Society
Volume124
Issue number27
DOIs
Publication statusPublished - 2002 Jul 10

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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