Homoconjugation vs. Exciton coupling in chiral α,β-unsaturated bicyclo[3.3.1]nonane Dinitrile and carboxylic acids

Abstract

The chiroptical properties of enantiomerically pure bicyclo[3.3.1]nona-2,6- diene-2,6-dicarbonitrile and related acids were studied by circular dichroism spectroscopy and theoretical computations. A consideration of the molecular structure of the synthesized difunctional compounds revealed that chromophores are predisposed to transannular through-space interaction due to a favourable conformation of the bicyclic skeleton and a rather small interchromophoric distance. Evidence for non-exciton- Type coupling between the two acrylonitrile and acrylate moieties in 3 and 4, respectively, was obtained by chiroptical spectroscopy and DFT calculations.