A theoretical study on the factors influencing cyanine photoisomerization: the case of thiacyanine in gas phase and in methanol (Articolo in rivista)

Type
Label
  • A theoretical study on the factors influencing cyanine photoisomerization: the case of thiacyanine in gas phase and in methanol (Articolo in rivista) (literal)
Anno
  • 2005-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/ct049899r (literal)
Alternative label
  • R. Improta (1), F. Santoro (2) (2005)
    A theoretical study on the factors influencing cyanine photoisomerization: the case of thiacyanine in gas phase and in methanol
    in Journal of chemical theory and computation
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • R. Improta (1), F. Santoro (2) (literal)
Pagina inizio
  • 215 (literal)
Pagina fine
  • 229 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url
  • http://pubs.acs.org/doi/abs/10.1021/ct049899r (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 1 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • a)Istituto di Biostrutture e Biommagini del CNR, via Mezzocannone 6, I-80134 Napoli, Italy. b) Istituto per i Processi Chimico-Fisici del CNR, Area della Ricerca del CNR di Pisa, via Moruzzi 1, I-56124 Pisa, Italy. (literal)
Titolo
  • A theoretical study on the factors influencing cyanine photoisomerization: the case of thiacyanine in gas phase and in methanol (literal)
Abstract
  • The effects influencing cyanine photoisomerization on the $S_1$ surface in the condensed phase have been investigated by an integrated quantum mechanical approach, focussed mainly on 3,3'-diEt-2,2'-thiacyanine. After excitation, a barrierless motion, involving the torsion coupled to bond skeletal deformation, leads to a slightly non-planar local $C_2$ minimum, which we propose to be the fluorescent state. Crossed a barrier of $\approx$ 120 cm$^{-1}$ a steeper path drives to a $C_1$ global minimum $S_1$-Min, corresponding to a pseudo-perpendicular twisted intramolecular charge transfer (TICT) state. CAS(6,6) optimization allows to locate the lowest energy $S_1/S_0$ conical intersection which is reached from $S_1$-Min by an increased asymmetry of the two rings and a marked pyramidalization at one N center. $S_1$ surface is rather flat in the Franck-Condon region and suggests that other paths can be competitive with the minimum energy one. The comparison among different cyanines shows how variation of the molecular scaffold and/or of its substituents modulate the dynamics of the photoisomerization. All the indications coming from our computations are in line with and provide an explanation to the available experimental results. (literal)
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