Two l-Proline Cadmium Thiocyanates with Moderate Second-Harmonic-Generation Responses and Large Birefringences.

Two organic-inorganic cadmium thiocyanates, namely, Cd(SCN)(l-CHNO) () and Cd(SCN)(l-CHNO) (), have been synthesized using l-proline as the bridging ligand. The two compounds have double-chain-like and layered structures, respectively. They feature moderate second-harmonic-generation responses (0.33 × KHPO for and 1.58 × KHPO for ), wide band gaps (4.68 eV for and 4.59 eV for ), and large birefringences (0.210 at 546 nm for and 0.295 at 546 nm for ). The structure-property relationship was explicated by first-principle calculations based on density functional theory.