Crystal chirality of the non-chiral inorganic salt, α-Ni(H2O)6•SO4

Solid phase circular birefringence (CB = optical rotatory dispersion) and circular dichroism (CD) spectra of alpha-Ni(H2O)(6) . SO4, which exhibits optical activity only in the crystalline state, were studied in the 250-600 nm region. A method was devised to remove signals which arise from linear birefringence (LB) and linear dichroism (LD) and give pure CB spectra by using a specially constructed universal chiroptical spectrophotometer. Even in the cases where LB is substantial, the pure CB and CD spectra thus obtained were shown to satisfy the Kramers-Kronig relationship in the (3)A(2g) --> T-3(1g)(P)Ni d-d transition region, as do chiral compounds in isotropic medium. (C) 2002 Elsevier Science B.V. All rights reserved.