Xu Xiang, Hu Chun-Li, Li Bing-Xuan, Mao Jiang-Gao
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, P.R. China), Fax.
Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, P.R. China.
Chemistry. 2016 Jan 26;22(5):1750-9. doi: 10.1002/chem.201504117. Epub 2016 Jan 7.
Two new polar potassium gold iodates, namely, K2 Au(IO3)5 (Cmc21) and β-KAu(IO3)4 (C2), have been synthesized and structurally characterized. Both compounds feature zero-dimensional polar Au(IO3)4 units composed of an AuO4 square-planar unit coordinated by four IO3(-) ions in a monodentate fashion. In β-KAu(IO3)4, isolated Au(IO3)4 ions are separated by K(+) ions, whereas in K2 Au(IO3)5, isolated Au(IO3)4 ions and non-coordinated IO3(-) units are separated by K(+) ions. Both compounds are thermally stable up to 400 °C and exhibit high transmittance in the NIR region (λ=800-2500 nm) with measured optical band gaps of 2.65 eV for K2 Au(IO3 )5 and 2.75 eV for β-KAu(IO3)4. Powder second-harmonic generation measurements by using λ=2.05 μm laser radiation indicate that K2 Au(IO3)5 and β-KAu(IO3)4 are both phase-matchable materials with strong SHG responses of approximately 1.0 and 1.3 times that of KTiOPO4, respectively. Theoretical calculations based on DFT methods confirm that such strong SHG responses originate from a synergistic effect of the AuO4 and IO3 units.
两种新型极性碘酸金钾化合物，即K2Au(IO3)5（空间群Cmc21）和β-KAu(IO3)4（空间群C2），已被合成并进行了结构表征。两种化合物均具有零维极性Au(IO3)4单元，该单元由一个平面正方形AuO4单元和四个以单齿方式配位的IO3(-)离子组成。在β-KAu(IO3)4中，孤立的Au(IO3)4离子被K(+)离子隔开，而在K2Au(IO3)5中，孤立的Au(IO3)4离子和未配位的IO3(-)单元被K(+)离子隔开。两种化合物在高达400°C时都具有热稳定性，并且在近红外区域（λ = 800 - 2500 nm）表现出高透过率，测得K2Au(IO3)5的光学带隙为2.65 eV，β-KAu(IO3)4的光学带隙为2.75 eV。使用λ = 2.05μm激光辐射进行的粉末二次谐波产生测量表明，K2Au(IO3)5和β-KAu(IO3)4都是可相位匹配的材料，其强SHG响应分别约为KTiOPO4的1.0倍和1.3倍。基于DFT方法的理论计算证实，这种强SHG响应源于AuO4和IO3单元的协同效应。
