The geometric parameters for Cz-BDT-SO 2 and Cz-BDF, obtained in analogy to Table , are listed in Table . Starting with the S 0 state of Cz-BDT-SO 2 , we find that its Cz/Ph torsion angles are almost unaltered when compared to the previous two molecules whereas the core/Ph torsion angles (θ 2 /θ 2 ) are significantly reduced indicating that the central Ph-core-Ph system is almost planar. Excitation into T 1 breaks the symmetry for Cz-BDT-SO 2 and one of the angles (θ 2 ) planarises even more whereas the other one remains largely unaltered. Interestingly, excitation into S 1 has the opposite effect and the θ 2 /θ 2 angles are slightly increased, which is the opposite trend to what was seen for Cz-BDT. Proceeding to Cz-BDF, we find that this molecule stays symmetric and fairly rigid in all states considered possessing a largely planar central Ph-core-Ph system. Finally, it is interesting to note that for all four molecules in this work, the bond distances change with the twisting angles. An increase/decrease in θ leads to an increase/decrease in d showing that the effect of enhanced conjugation produced by a smaller torsion angle also affects the bond distances.