Hydrogen bonding interactions on molecular properties of pesticidal compound 4-nitrophthalic acid: experimental density functional theory computations, electron localized function, localized orbital locator analysis and molecular docking scrutiny

Nitroaromatic compounds are expansively used in the manufacturing of pharmaceuticals, pesticides, plasticizers, azo dyes and explosives. Nitrophenolic compounds can accumulate in the soil as a result of hydrolysis of several insecticides such asparathion, methyl parathion, and fenitrothion which can cause propitious effects to the biological systems. In optimized geometry hyperconjugation of nitro and dicarboxylic acid groups with the ring system increases the electron density of the aromatic system. Electron localized Function and Localized orbital Locator Analysis has value in a region wherein indicates high localization of electrons due to the presence of covalent bond, a lone pair of electrons or a nuclear shell in that region. In Nuclear Magnetic Resonance analysis signals in highly deshielded region clearly indicates the presence of carboxylic carbon in the compound. From vibrational assignments, broadening and red shifting depicts the level of intermolecular hydrogen bonding. <i>In-vitro</i> antimicrobial activity results clearly reveal that in all the four strains, activity increases with increase in compound concentration and the inhibition of the strains also increases. From both molecular docking and In-vitro Antimicrobial Activity the title compound can be certified that it inhibits antimicrobial activity and it is a pesticide.

硝基芳香族化合物（Nitroaromatic compounds）被广泛应用于医药、农药、增塑剂、偶氮染料及炸药的生产制造。硝基酚类化合物可经由对硫磷、甲基对硫磷、杀螟硫磷等多种杀虫剂的水解作用在土壤中蓄积，进而对生物系统产生有利影响。在优化几何构型下，硝基与二羧酸基团与环系之间的超共轭作用可提升芳香体系的电子密度。定域电子函数（Electron Localized Function）与定域轨道定位器分析在特定区域具有应用价值，该区域因共价键、孤对电子或核壳层的存在而呈现较高的电子定域化程度。核磁共振（Nuclear Magnetic Resonance）分析中，高去屏蔽区域的信号可明确指示化合物中存在羧酸碳。从振动指认结果来看，谱峰展宽与红移现象可反映分子间氢键的作用强度。体外（In-vitro）抗菌活性实验结果清晰显示，在所测试的4种菌株中，抗菌活性随化合物浓度升高而增强，菌株的抑制率也同步提升。结合分子对接与体外抗菌活性实验结果，可以证实标题化合物具备抗菌活性，且属于农药范畴。