Multiple aspects of chirality in coordination polymers formed by the uranyl ion with (1R,3S)-(+)-camphorate ligands

Abstract

Following previous work on complexes of the anions of (1R,3S)-(+)-camphoric acid (H2cam) with the uranyl cation, three novel species have been synthesized under solvo-hydrothermal conditions. [UO2(Hcam)2(4,4ʹ-bipy)] (1), where 4,4ʹ-bipy is 4,4ʹ-bipyridine, crystallizes as a monoperiodic polymer with bridging 4,4ʹ-bipy molecules and chelating, terminal Hcam– anions, hydrogen bonding between carboxylic and carboxylate groups in adjacent chains giving diperiodic networks. [UO2(cam)(2,2ʹ-bipy)] (2), where 2,2ʹ-bipy is 2,2ʹ-bipyridine, crystallizes also as a monoperiodic polymer, but bis-chelating cam2– anions are here bridging and the chelating 2,2ʹ-bipy ligands induce chirality at the uranium atoms; the chains are helical, left- or right-handed depending on the chirality of the associated uranium centres. [Zn(phen)3][(UO2)2(cam)3] (3), where phen is 1,10-phenanthroline, is an anionic diperiodic network with hcb topology displaying a grooved shape. In all three instances, the enantiomeric purity of the camphorate ligands does not produce significant enantioselectivity in regard to other aspects of the structural chirality.