Alkali-metal isocyanurate Cs3(H2C3N3O3)3(H3C3N3O3)·3H2O: synthesis and characterization

Cyanurate or isocyanurate compounds containing plane π-conjugated groups usually have giant optical anisotropy, which are promising candidates for optoelectronic functional materials. In this work, a new alkali-metal isocyanurate was successfully synthesized by a hydrothermal method, namely Cs3(H2C3N3O3)3(H3C3N3O3)·3H2O, belonging to the triclinic crystal and P space group. The compound has two-dimensional layers constructed with (H2C3N3O3)− and (H3C3N3O3) six-membered rings extending along the ab plane. The characterization results show that it exhibits a wide band gap (5.03 eV) and a large birefringence (0.23 at 1064 nm). In addition, in order to evaluate the relationship between the crystal structure and its optical properties, the first-principles calculation was also carried out. This work provided a possible candidate for anisotropic optical crystals applied in the ultraviolet region.