title: Excited-state dynamics of thiophene substituted betaine pyridinium compounds.
abstract: This work deals with the photophysics of novel pyridinium betaine based on 2-pyridin-1-yl-1H-benzimidazole (SBPa) substituted symmetrically by mono- (Th2SBPa) and bi-thiophene fragments (Th4SBPa). The study is based on a combination of steady-state, femtosecond transient absorption spectroscopic measurements supported by PCM-(TD)DFT calculations. It is found that the two step ICT process (S0 → S2 excitation followed by S2(CT) → S1(CT) internal conversion) occurring for the parent molecule remains unaffected for Th2SBPa while the situation is less clear for Th4SBPa. Actually, for both molecules, a new decay route involving the π-electron system localized in thiophenic groups is responsible for the production of triplet states. Involvement of this new route in the parallel production of S1(CT) is strongly suspected.
authors.affiliation: Laboratoire de Spectrochimie Infrarouge et Raman CNRS UMR 8516, Université de Lille1 Sciences et Technologies, Université Lille Nord de France, Bat C5, 59655 Villeneuve d'Ascq Cedex, France. stephane.aloise@univ-lille1.fr.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Aloïse
authors.forename: Zuzanna
authors.initials: Z
authors.lastname: Pawlowska
authors.forename: Olivier
authors.initials: O
authors.lastname: Poizat
authors.forename: Guy
authors.initials: G
authors.lastname: Buntinx
authors.forename: Aurélie
authors.initials: A
authors.lastname: Perrier
authors.forename: François
authors.initials: F
authors.lastname: Maurel
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ohkawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kimoto
authors.forename: Jiro
authors.initials: J
authors.lastname: Abe