On the origin of optical activity in crystal structures

Close examination of published measurements of absolute configuration in inorganic crystals has revealed many mistakes, and only a small number of published correlations between optical rotation and chirality of crystal structure can be trusted. The sense of rotation of light is here traced to the hand of specific helices of atoms, provided that the latter are correctly chosen. Four principles are given for choosing the helices. The crystals described are: low-quartz, α-AlPO₄, α-HgS, Ca₂Sr(C₂H₅COO)₆, Bi₁₂SiO₂₀, NaClO₃, NaBrO₃ and α-LiIO₃. The principles suggest that the published absolute configuration of α-LiIO₃ must be incorrect {subsequently proved experimentally by Stadnicka, Glazer & Moxon [J. Appl. Cryst. (1985), 18, 237–240]}.