A comparative study on the photochemistry of two bipyridyl derivatives: [2,2′-Bipyridyl]-3,3′-diamine and [2,2′-bipyridyl]-3,3′- diol

Juan Manuel Ortiz-Sánchez, Ricard Gelabert, Miquel Moreno, José M. Lluch

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15 Citations (Scopus)

Abstract

The two isoelectronic bipyridyl derivatives, [2,2′-bipyridyl]-3, 3′-diamine and [2,2′-bipyridyl]-3,3′-dial, are experimentally known to undergo very different excited-state double-proton-transfer processes, which result in fluorescence quantum yields that differ by four orders of magnitude. Herein, density functional theory (DFT), time-dependent DFT (TDDFT), and complete active space self-consistent field (CASSCF) calculations are used to study the double-proton-transfer processes in the ground and first singlet π→π* excited state. The quantum-chemistry calculations indicate 1) the existence of only one energy minimum in the ground electronic state corresponding to reactants (thus avoiding the possibility of a fast fluorescent relaxation process from the photoproducts region), 2) an endoergic process of the complete double proton transfer, and 3) the presence of a conical intersection in the excited intermediate region of [2,2′-bipyridyl]-3, 3′-diamine. These facts explain the very low fluorescence quantum yield in [2,2′-bipyridyl]-3,3′-diamine compared to [2,2′-bipyridyl]-3, 3′-diol. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.
Original languageEnglish
Pages (from-to)1199-1206
JournalChemPhysChem
Volume8
Issue number8
DOIs
Publication statusPublished - 4 Jun 2007

Keywords

  • Density functional calculations
  • Excited states
  • Femtochemistry
  • Proton transfer
  • Reaction mechanisms

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