Na 10 Zn(NO 3 ) 4 (SO 3 S) 4 : a nonlinear optical crystal combining inorganic π-conjugated and non-π-conjugated heteroanion groups

The research on nonlinear optical (NLO) crystals is mainly focused on two relatively separate systems, π-conjugated or non-π-conjugated systems, respectively. In this work, we report a new NLO crystal Na 10 Zn(NO 3 ) 4 (SO 3 S) 4 combining inorganic π-conjugated [NO 3 ] and non-π-conjugated heteroanion [S 2 O 3 ] groups, which was synthesized by the aqueous solution method. In the structure, the similar coexistence of planar triangular anionic groups (π-conjugated) and heteroanion tetrahedra (non-π-conjugated) is rarely mentioned, which provides a new approach for designing NLO crystals. Notably, this compound exhibits a phase-matching second-harmonic generation (SHG) response 1.2 times that of KH 2 PO 4 . In addition, birefringence, absorption edge and theoretical calculations are also reported in this article. This work provides a new designing route to expand NLO systems via combining planar π-conjugated and non-π-conjugated heteroanion groups.