4-Dimethylaminopyridinium 3,5-dinitrobenzoate (DMAPDNBA), a charge transfer complex, was synthesized and successfully grown by slow evaporation solution growth technique. Single-crystal X-ray diffractogram reveals that the material crystallizes in orthorhombic system with non-centrosymmetric space group P212121 with cell parameters a = 5.92 A, b = 13.77 A, c = 18.64 A, and V = 1519 A3. Powder XRD and FTIR spectral investigation were carried out to analyse the crystallinity of the material and for assigning vibrations to identify the different functional groups existing within the material. The optical transmittance in the visible and near IR (400–800 nm) regions with lower cutoff wavelength of 227 nm, luminescence spectrum, and the optical band gap of 5.45 eV sufficiently fulfilled the requirement for non-linear optical applications. The thermal exploration analysis (TG–DSC) confirmed the stable nature of the compound up to 190 °C, and dielectric constant measurement of the obtained sample enhanced the property of non-linear optical activity at higher frequencies. The mechanical property of DMAPDNBA was evaluated using Vickers’s hardness test which confirmed that the material belonged to the soft category. The frequency conversion efficiency of the grown sample was measured to be eightfold that of the reference potassium dihydrogen phosphate, which exploits the potentiality of the charge transfer complex to be used as a promising candidate for various laser-assisted NLO applications. Third-order non-linearity was measured adopting Z-Scan technique, and the optical limiting/switching efficiency of the complex was verified with the optical limiting threshold value of 10.64 J/cm2 and figure of merit property, confirming the capability of the material for switching applications. The threshold value of laser damage was found to be 1.74 GW/cm2. Theoretical investigations were performed using density functional theory (DFT-B3LYP) approach to estimate and predict various linear and non-linear optical properties of the DMAPDNBA complex. The first-order hyperpolarizability value of the DMAPDNBA molecule was found to be 19 times that of the standard organic crystal, urea. In short, all the above findings designate the candidature of the charge transfer complex, DMAPDNBA, for photonic applications.

中文翻译：

---

用于光学限制应用的正交晶体的线性和非线性光学参数的实验和计算观点

4-Dimethylaminopyridinium 3,5-dinitrobenzoate (DMAPDNBA) 是一种电荷转移复合物，通过缓慢蒸发溶液生长技术合成并成功生长。单晶 X 射线衍射图显示材料在正交系统中结晶，具有非中心对称空间群 P212121，晶胞参数 a = 5.92 A、b = 13.77 A、c = 18.64 A 和 V = 1519 A3。进行粉末 XRD 和 FTIR 光谱研究以分析材料的结晶度并分配振动以识别材料中存在的不同官能团。可见光和近红外（400-800 nm）区域的光透射率具有较低的截止波长 227 nm、发光光谱和 5.45 eV 的光学带隙，足以满足非线性光学应用的要求。热探测分析（TG-DSC）证实了该化合物在高达 190 °C 时的稳定性，所得样品的介电常数测量增强了更高频率下非线性光学活性的特性。DMAPDNBA 的力学性能使用维氏硬度测试进行评估，确认该材料属于软类别。经测量，生长样品的频率转换效率是参考磷酸二氢钾的八倍，这利用了电荷转移复合物的潜力，可用作各种激光辅助 NLO 应用的有希望的候选物。采用Z-Scan技术测量三阶非线性，并以10的光限阈值验证复合物的光限/开关效率。64 J/cm2 和品质因数特性，证实了材料在开关应用中的能力。发现激光损伤的阈值为 1.74 GW/cm2。使用密度泛函理论 (DFT-B3LYP) 方法进行了理论研究，以估计和预测 DMAPDNBA 复合物的各种线性和非线性光学特性。发现 DMAPDNBA 分子的一级超极化值是标准有机晶体尿素的 19 倍。简而言之，上述所有发现都表明电荷转移复合物 DMAPDNBA 可用于光子应用。使用密度泛函理论 (DFT-B3LYP) 方法进行了理论研究，以估计和预测 DMAPDNBA 复合物的各种线性和非线性光学特性。发现 DMAPDNBA 分子的一级超极化值是标准有机晶体尿素的 19 倍。简而言之，上述所有发现都表明电荷转移复合物 DMAPDNBA 可用于光子应用。使用密度泛函理论 (DFT-B3LYP) 方法进行了理论研究，以估计和预测 DMAPDNBA 复合物的各种线性和非线性光学特性。发现 DMAPDNBA 分子的一级超极化值是标准有机晶体尿素的 19 倍。简而言之，上述所有发现都表明电荷转移复合物 DMAPDNBA 可用于光子应用。