On the origin of optical activity in crystal structures

Abstract

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, ~-A1PO4, ct-HgS, Ca2Sr(CzHsCOO)6, BitzSiO2o, NaC103, NaBrO 3 and ~-LiIO 3. The principles suggest that the published absolute configuration of ~t-LiIO3 must be incorrect {subsequently

Structure, absolute configuration and optical activity of α-nickel sulfate hexahydrate

“…A number of approximations have had to be made in this example, but, even so, the results of our computations are most encouraging. As with the examples used by Glazer & Stadnicka (1986) and by Devarajan & Glazer (1986), it is seen that the major influence on the optical properties comes from the structural arrangement of the atoms in the crystal.…”

“…Following Glazer & Stadnicka (1986) we first choose the most polarizable atoms, which, in this structure, are the O atoms. Because the Ni-O bonds are weaker than the S-O bonds (as shown by the relative bond distances), O(1), 0(2) and 0(3) will have larger electronic polarizabilities than 0(4) and O(5), and so they should contribute more strongly towards the optical activity.…”

“…In the present paper, we describe a new X-ray structure determination, including for the first time the absolute configuration. We also discuss the optical rotatory dispersion in connection with the work of Glazer & Stadnicka (1986) and of Devarajan & Glazer (1986). It is important to realise that all other studies of optical activity in this compound have so far concentrated exclusively on the d-d transitions in the metal ion, and therefore relate only to the relevant CD and absorption bands within the observable wavelength range.…”

“…Those inorganic crystals for which the true absolute configuration is known were shown by Glazer & Stadnicka (1986) to have structural helices of polarizable atoms, 0108-7681/87/040319-07501.50 whose sense could be related closely to the sense of rotation of plane-polarized light. A set of rules was given to enable these helices to be correctly chosen.…”

Absolute configuration, polarity, morphology and optical activity of α-LiIO3

“…Using this relation and the conclusions of LFC, they found a correlation between the absolute structure and the optical chirality. From a structural approach to optical activity, Glazer & Stadnicka (1986) (GS) showed that the determination of the structural enantiomorph by LFC seemed to be in error. Stadnicka, Glazer & Moxon (1985) (SGM) redetermined the absolute configuration of LilO3 and showed that the correlation between the absolute configuration and the optical chirality found by LFC and SALKA was incorrect.…”