α- and β-(CHNO)(IO)·HIO: Two SHG Materials Based on Organic-Inorganic Hybrid Iodates.

Organic-inorganic hybrid nonlinear optical (NLO) materials are highly anticipated because of the integration of both merits of the organic and inorganic moieties. Herein, the 2-pyrimidinone cation (CHNO) has been incorporated into the iodate system to form two polymorphic organic-inorganic hybrid iodates, namely, α- and β-(CHNO)(IO)·HIO. They crystallize in different polar space groups ( and 2), and their structures feature one-dimensional (1D) chain structures composed of (CHNO) cations, IO anions, and HIO molecules interconnected via hydrogen bonds. α- and β-(CHNO) (IO)·HIO exhibit strong and moderate second-harmonic-generation (SHG) responses of 6.4 and 0.9 × KHPO (KDP), respectively, the same band gaps of 3.65 eV, and high powder laser-induced damage threshold (LIDT) values [51 and 57 × AgGaS (AGS)]. The results of theoretical calculations revealed that the large SHG effect of α-(CHNO)(IO)·HIO originated from the IO and HIO groups. This work indicates that (CHNO) is a potential group for designing new NLO materials with brilliant optical performances.