Zihao Yu,Qingran Ding,Yuhang Jiang,Weiqi Huang,Changsheng Yang,Sangen Zhao,Junhua Luo
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 Na10Zn(NO3)4(SO3S)4 combining inorganic π-conjugated [NO3] and non-π-conjugated heteroanion [S2O3] 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 KH2PO4. 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.
By probing the electric potential at the hexadecane–water interface with second harmonic generation and the zeta potential at the surface of a hexadecane droplet in its emulsion, we show that hydronium ions don't have a specific affinity to the oil–water interface although hydroxide ions do. The observed apparent affinity of the hydronium ions to the hexadecane–water interface is more likely a result of the electro-static attraction effect. The adsorption free energy of the hydroxide ions at the oil–water interface was estimated to be −8.3 kcal mol−1. This study provides more experimental evidence for understanding the behavior of hydronium and hydoxide ions at the oil–water interface.
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