Intramolecular charge transfer of push-pull pyridinium salts in the singlet manifold.
The solvent effect on the photophysical and photochemical properties of the iodides of three trans (E) isomers of 2-D-vinyl,1-methylpyridinium, where D is a donor group (4-dimethylaminophenyl, 3,4,5-trimethoxyphenyl and 1-pyrenyl), was studied by stationary and transient absorption techniques. The results obtained allowed the negative solvatochromism and relaxation pathways of the excited states in the singlet manifold to be reasonably interpreted. Resorting to ultrafast absorption techniques and DFT calculations allowed information on the excited state dynamics and the role of the solvent-controlled intramolecular charge transfer (ICT) processes to be obtained. The structure-dependent excited state dynamics in nonpolar solvents, where the ICT is slower than solvent rearrangement, and in polar solvents, where an opposite situation is operative, was thus explained. The push-pull character of the three compounds, particularly the anilino-derivative, suggests their potential application in optoelectronics.
Department of Chemistry, Biology and Biotechnology and Centro di Eccellenza sui Materiali Innovativi Nanostrutturati (CEMIN), University of Perugia , via Elce di Sotto 8, 06123 Perugia, Italy.
Benedetta
B
Carlotti
Giuseppe
G
Consiglio
Fausto
F
Elisei
Cosimo G
CG
Fortuna
Ugo
U
Mazzucato
Anna
A
Spalletti
D011726:Pyridinium Compounds / Q000737:chemistry*; D011789:Quantum Theory; D012492:Salts / Q000737:chemistry
D011726:Pyridinium Compounds; D012492:Salts