Trends in the TD-DFT calculations of porphyrin and phthalocyanine analogs

John Mack, Justin Stone, Tebello Nyokong

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

In 2005, Kobayashi and coworkers reported trends in the TD-DFT spectra of 17 Zn(II) porphyrinoids [J. Am. Chem. Soc. 2005;127:17697] that were analyzed using Michl's perimeter model as part of a study of the anomalous magnetic circular dichroism (MCD) spectroscopy of zinc tetraphenyltetraacenaphthoporphyrin. In recent years, it has become increasingly clear that TD-DFT calculations with the commonly used hybrid B3LYP exchange-correlation functional of the Gaussian software package are problematic in the B-band region of porphyrinoid spectra, since the degree of confgurational interaction between the B and higher energy ππ state appears to be signifcantly overestimated. The CAM-B3LYP functional is now often preferred for analyzing the optical properties of porphyrinoids, since it includes a long-range correction of the exchange potential, which incorporates an increasing fraction of Hartree-Fock (HF) exchange as the interelectronic separation increases, making it better suited for studying compounds where there is signifcant charge transfer in the electronic excited states. The trends in the TD-DFT calculations are reexamined with a wider range porphyrinoid compounds including several with pyrazino moieties and are found to provide a closer agreement with the experimental in the B-band region for complexes such as zinc tetraphenylporphyrin and phthalocyanine.

Original languageEnglish
Pages (from-to)630-641
Number of pages12
JournalJournal of Porphyrins and Phthalocyanines
Volume18
DOIs
Publication statusPublished - 2014 Aug

Keywords

  • MCD spectroscopy
  • Phthalocyanines
  • Porphyrins
  • TD-DFT calculations
  • Tetraazaporphyrins

ASJC Scopus subject areas

  • Chemistry(all)

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