Syntheses, structures, photoluminescence and photocatalysis of chiral 3D Cd(II) frameworks from achiral mixed flexible ligands by spontaneous resolution.

Unprecedented two homochiral Cd(ii) enantiomers [Cd(dtba)(bpp)]n (1: 1P and 1M) (H2dtba = 2,2'-dithiodibenzoic acid, bpp = 1,3-bis(4-pyridyl)propane), were obtained by self-assembly with mixed achiral flexible ligands. Single-crystal X-ray diffraction analysis reveals that complexes 1P and 1M crystallize in trigonal space groups P3121 and P3221, respectively. The compounds are optically active, and their UV spectra in the solid state showed Cotton effects in the opposite directions. Compounds 1P and 1M present the examples of three-interpenetrating chiral frameworks with triangular and quasi-heart-like threefold helical chiral channels, chair-like twofold helical chiral channels and one type of threefold double-helical chain. The 3D metal-organic framework can be regarded as a bcu-type topology with the symbol of 8(6). The photoluminescent properties of compound 1 have been studied. Remarkably, compound 1 exhibits good photocatalytic activity for degradation of dyes under the simulated sunlight irradiation in the pH = 3 aqueous solution.