P. Gedeck et S. Schneider, Numerical self-consistent reaction field study of the excited-state properties of p-(dimethylamino)-benzonitrile derivatives, J PHOTOCH A, 121(1), 1999, pp. 7-15
Citations number
33
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
Since the first observation of the dual fluorescence of p-(dimethylamino)-b
enzonitrile (p-DMABN) by Lippert et al. [E. Lippert, W. Luder, E Moll, W. N
agele, H. Boos, H. Prigge, I.Seilbold-Blankenstein, Angew. Chem. 21, (1961)
695], many theories were proposed to explain this interesting behaviour. S
o far, the model proposed by Rotkiewicz in 1973 [K. Rotkiewicz, K.L. Grellm
an, Z.R. Grabowski, Chem. Phys. Lett. 19, (1973) 315] has gained the widest
acceptance, despite doubts being expressed about its validity. Zachariasse
et al. [K.A. Zachariasse, Th. von der Haar, A. Hebecker, U. Leinhos, W. Ku
hnle, Pure. Appl. Chem. 65, (1993) 1745; K.A. Zachariasse, Th. von der Haar
, U. Leinhos and W. Kuhnle, J. Inf. Rec. Mats. 21, (1994) 501] base their c
ritique, beside other experimental observations, on the lack of dual fluore
scence in two groups of p-DMABN derivatives. One comprises the methyl subst
ituted isomers p-(amino)-benzonitrile (p-ABN) and p- (methylamino)-benzonit
rile (p-MABN), the other the cyano substituted isomers m-(dimethylamino) -b
enzonitrile (m-DMABN) and 3,5-dicyanodimethylaniline (DCDMA). Although thes
e derivatives are structurally not too different from p-DMABN, it is not ob
vious whether the similarity is large enough to provide evidence for the in
validity of the TICT model in the parent compound. in this contribution, th
erefore, we will present the results of a semi-empirical study using a nume
rical self-consistent reaction field model to describe the solvent influenc
e on the excited state properties of the above mentioned derivatives. As wi
ll be demonstrated, the non-existent anomalous fluorescence can be rational
ized by the changed electronic properties of the different compounds. The d
ifferent photophysical behaviour of the p-DMABN derivatives alone cannot be
used to doubt the validity of the TICT model in case of p-DMABN. (C) 1999
Elsevier Science S.A. All rights reserved.