Acentric Organic-Inorganic Hybrid Halide [N(CH3)4]2HgBr2I2 Featuring an Isolated [HgBr2I2]2- Tetrahedron and Second-Order Nonlinearity

A new hybrid compound [N(CH3)(4)](2)HgBr2I2, obtained by a hydrothermal reaction, crystallized in the non-centrosymmetric space group P2(1)2(1)2(1). Its structure contains an isolated asymmetric [HgBr2I2](2-) tetrahedron with net polarization, connected by hydrogen bonds to form pseudo-one-dimensional chain structures. Moreover, its optical band gap, nonlinear optical (NLO) property, fluorescence property, and thermal property were characterized in detail. A rare high-temperature phase transition was observed in the compound. In addition, theoretical calculations were performed to elaborate the relation between electronic state, band structure, and their nonlinear optical response. These results indicate that [N(CH3)(4)](2)HgBr2I2 is a new potential candidate for future photoelectronic applications in fluorescence and nonlinear optics.

Automated summary

The new hybrid compound, [N(CH3)(4)](2)HgBr2I2, crystallized in a non-centrosymmetric space group and exhibited unique optical and thermal properties. Experimental results indicated that it formed pseudo-one-dimensional chain structures connected by hydrogen bonds, with a rare high-temperature phase transition observed. Theoretical calculations further demonstrated its potential for future applications in fluorescence and nonlinear optics.