Homochiral ferroelectric three-dimensional cadmium(II) frameworks from racemic camphoric acid and 3,5-di(imidazol-1-yl)benzoic acid

Two three-dimensional (3D) chiral frameworks, [Cd-6(L)(4)(D-Cam)(4)(H2O4)center dot 2H(2)O (1D) and [Cd-6(L)(4)(L-Cam)(4) (H2O)(4))center dot 2H(2)O (1L) [HL = 3,5-di(imidazol-1-yl)benzoic acid, D-H(2)Cam= D-camphoric acid, r-H(2)Cam=L-camphoric acid], have been synthesized under hydrothermal conditions, which represent a nice example of enantioselectivity of organic racemic ligands (DL-camphorates) during the self-assembly process and formation of the metal complexes. Compounds 1D and 1L feature 3D framework with chiral chains constructed by Cd(II) cations and camphorate anions. Solid-state circular dichroism (CD) spectra of 1D and 1L revealed that they are enantiomers. Furthermore, the complex with chiral C2 space group displays ferroelectric behavior with a remnant electric polarization (P-r) of similar to 0.140 mu C/cm(2) and an electric coercive field (E,) of similar to 17.11 kV/cm. (C) 2011 Elsevier B.V. All rights reserved.