A high-power chiral dopant system involving 6-coordinate metal complexes was designed on the basis of a shape model. Accordingly, a series of mixed 1,3-diketonate complexes of Ru(III), [Ru(acac)2(L-n)], in which acac = acetylacetonate and L-n = dibenzoylmethanate substituted with n octyloxy groups (abbreviated as Ru-n hereafter), was prepared and optically resolved. Their performance as chiral dopants was evaluated in terms of helical twisting power (HTP) in a room-temperature nematic liquid crystal, N-(4- methoxybenzylidene)-4-n-butylaniline (MBBA), by measuring the helical pitch lengths and CD spectra for the induced chiral nematic phases. The Δ- and Λ-enantiomers induced macroscopic left-handed (A/) and right-handed (P) helices, respectively, and the (absolute) values for HTP have proven to be remarkably large, e.g. βM = 1.8 × 102 μm-1 in the case of Λ-Ru-2. The induced CD spectra for the dilute MBBA* materials (the asterisk denotes in this paper that MBBA has been doped with a chiral substance) were fit to the interpretation that persistent helical alignment of host molecules was generated. We also performed quantum chemical calculations for the optimum configuration of model Al(III) complexes with and without MBBA molecules and found that two liquid crystal molecules will eventually form a negative dihedral angle (left-handed twist) over the A-enantiomer of dialkylated complex. © 2005 American Chemical Society.