Pregledni rad

Ab Initio Calculations and Mechanistic Analyses of Optical Activity of Organic Molecules with Extended Chromophores

Thomas D. Bouman ; Department of Chemistry, Southern ILlinois University, Edwardsvile, Illinois 62026, USA
Aage E. Hansen ; Department of Physical Chemistry, H. C. 0rsted Institute, University of Copenhagen, DK-2100 Copenhagen 0, Denmark

Sažetak

Molecular orbital calculation of electronic transition energies
and oscillator and rotatory strengths in the random phase approximation (RPA) is reviewed, and it is outlined how the three
mechanisms contained in Kirkwood's theory of optical rotatory
power and other features of the excitations may be extracted
from such calculations. The method is applied to the chiroptical
properties of cis,trans-(1,3)-cyclooctadiene and bicyclo[2.2.1Jhept-
5-en-2-one, both of which contain an extended chromophoric
system. The results for the diene support Sandstrom's assignment
of P helicity to the (-)-enantiomer despite the prediction of
simple Diene Rule, and structural and spectral similarities to
(-)-trans-cyclooctene are strong. The enone calculations confirm
the model assumptions about the predominance of a ,u-m rotatory
strength mechanism whereas the analysis of the bond eontributions
and of the transition moment direction differs significantly
from the assumptions governing the chirality rule of
Schippers and Dekkers and other models.

Ključne riječi

Hrčak ID:

175395

URI

https://hrcak.srce.hr/175395

Datum izdavanja:

30.6.1989.

Posjeta: 548 *