Li Shu-Fang, Hu Liang, Tang Ru-Ling, Ma Yao, Mao Fei-Fei, Zheng Jie, Zhang Xiu-Du, Yan Dong
Key Laboratory of Functional Molecular Solids, Ministry of Education, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241002, China.
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, P. R. China.
Inorg Chem. 2022 Sep 19;61(37):14880-14886. doi: 10.1021/acs.inorgchem.2c02521. Epub 2022 Sep 2.
In order to meet the growing needs for the laser technology and optics industries, the goal is to find suitable fundamental building blocks with large nonlinear-optical (NLO) coefficients and birefringence for an excellent-performance NLO or birefringent system. Via preliminary investigations and calculations, it has been found that the planar π-conjugated group (CHO) possesses large polarizability anisotropy (δ) and hyperpolarizability (β), comparable to well-known groups such as (BO), (CNO), etc. Herein, we report a new alkali-metal 3,5-dicarboxybenzoate, KCHO(HO) (KHBTC), which crystallized in the acentric space group 2. Second-harmonic-generation (SHG) measurements of KHBTC under 1064 nm laser radiation show that the SHG response of KHBTC is 1.2 times that of KDP with type I phase-matching behavior. Birefringence measurements show that KHBTC owns a large birefringence of about 0.372 at 550 nm. The band gap of KHBTC obtained by ultraviolet (UV) diffuse-reflectance spectroscopy is 3.91 eV, indicating that KHBTC has potential applications as UV NLO or birefringent materials. Theoretical calculation further confirmed that the impressive optical properties of KHBTC are derived from the large polarizability anisotropy of the (CHO) anions.
为了满足激光技术和光学行业不断增长的需求，目标是找到具有大的非线性光学（NLO）系数和双折射的合适基本构建块，以构建高性能的NLO或双折射系统。通过初步研究和计算，发现平面π共轭基团（CHO）具有大的极化率各向异性（δ）和超极化率（β），与诸如（BO）、（CNO）等知名基团相当。在此，我们报道了一种新型碱金属3,5 - 二羧基苯甲酸盐KCHO(HO)（KHBTC），它结晶于非中心空间群2。在1064 nm激光辐射下对KHBTC进行的二次谐波产生（SHG）测量表明，KHBTC的SHG响应是具有I型相位匹配行为的KDP的1.2倍。双折射测量表明，KHBTC在550 nm处具有约0.372的大双折射。通过紫外（UV）漫反射光谱法获得的KHBTC的带隙为3.91 eV，表明KHBTC作为紫外NLO或双折射材料具有潜在应用。理论计算进一步证实，KHBTC令人印象深刻的光学性质源于（CHO）阴离子的大极化率各向异性。
