Profiling energetics and spectroscopic signatures in prototropic tautomers of asymmetric phthalocyanine analogues

J Phys Chem A. 2012 Jul 12;116(27):7364-71. doi: 10.1021/jp304386x. Epub 2012 Jun 29.

Abstract

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) were used to explain discrepancies in UV-vis and MCD spectra of the metal-free tribenzo[b,g,l]thiopheno[3,4-q]porphyrazine (1), substituted tribenzo[b,g,l]porphyrazine (2), and 2,3-bis(methylcarboxyl)phthalocyanine (3). On the basis of gas-phase and polarized continuum solvation model (PCM) DFT and TDDFT calculations, it was suggested that both NH tautomers contribute to the spectroscopic signature of 1, whereas the Q-band region of 2 and 3 is dominated by a single NH tautomer. For all tested compounds, it was found that the combination of the BP86 exchange-correlation functional, 6-31G(d) basis set, and TDDFT-PCM approach provides the best accuracy in energies of the Q(x)- and Q(y)-bands of the individual NH tautomers as well as correctly describes their relative energy differences, which are important in understanding of experimental spectroscopy of the target systems.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Gases
  • Indoles / chemistry*
  • Isoindoles
  • Kinetics
  • Porphyrins / chemistry*
  • Quantum Theory
  • Solvents
  • Spectrum Analysis
  • Stereoisomerism
  • Thermodynamics

Substances

  • Gases
  • Indoles
  • Isoindoles
  • Porphyrins
  • Solvents
  • phthalocyanine