Helical twisting power and scaled chiral indices

Chirality of optically active liquid crystal molecules has become an important research topic and the subject of a number of theoretical and experimental studies. We present here the results of the application of a newly developed scaling method of a chiral index to a range of chiral molecules. Good agreement is found between the scaled chiral index and the helical twisting power for relatively rigid molecules. Two flexible TADDOL (α,α,α′,α′-tetraaryl-1,3-dioxolan-4,5dimethanol) molecules are studied to determine which conformations may give rise to their high experimental helical twisting powers. A variety of links between the moment of inertia tensor, the dihedral angles, the scaled chiral indices, the minimum energy of the optimized geometry and the experimental helical twisting power are discussed. The scaled chiral and steric indices and dihedral angles are promising as predictors of experimental helical twisting power, in particular for relatively rigid molecules, in cases where all the relevant interactions are determined by the molecular structure.