S. Marguet et al., ELECTRONIC STATES OF MULTICHROMOPHORIC PHENYLETHYNYLBENZENE DERIVATIVES - EXCITON THEORY AND CS-INDO-CIPSI CALCULATIONS, Chemical physics, 208(3), 1996, pp. 351-373
The singlet electronic states of hexaphenylethynylbenzene derivatives
are calculated combining S-CI calculations in the pi system and CS-IND
O-CIPSI calculations in the sigma and pi systems (conformations spectr
a-intermediate neglect of differential overlap-configuration interacti
on by perturbative selected iterations). S-CI calculations (singly con
figuration interaction) in the pi system using localized pi MOs on eac
h chromophore are performed in order to characterize the nature (local
ized or delocalized) of the excited states of these multichromophoric
compounds. It is shown that simple considerations based on exciton the
ory allow the prediction of these excited states. The effects of symme
try lowering upon the spectroscopic properties of the hexaphenylethylb
enzene derivatives arising from orientational disorder of the outer be
nzene rings are compared to those arising from a methoxy substitution
of the central aromatic core. The CS-INDO-CIPSI method, in a version r
ecently modified by us, gives excellent results to interpret the elect
ronic spectra of very large molecules. More generally, this theoretica
l work provides directions concerning the way to modify the spectrosco
pic properties of phenylethynylbenzene derivatives.