The simplest derivatives of benzoic acid show a wide spectrum of the biological action mostly being poor water soluble. In order to demonstrate on example of 3,5-dinitrobenzoic acid (DNBA) a possibility of the simultaneous enhancement of water solubility and antimicrobial activity the complexation (salt formation and metal coordination) approach has been examined. Monoethanolamine (MEA) is selected as the complexing agent. Three isomorphic mixed-ligand complexes of Cu, Ni, Co with DNBA and MEA as well one organic salt in the polymorphic form have been synthesized and their structures are characterized by the element analysis, FTIR and X-ray crystallography. Measurements of water solubility and determination of the antimicrobial activity attest that a solubility of the copper mixed-ligand complex and organic salt is increased about four and eight times with simultaneous enhancement of the bioactivity. The DFT studies by B3LYP/def2-TZVP and B3LYP/6-311G (d,p) showed that Cu, Ni, and Co complexes with DNBA and MEA have high-spin ground electronic states as a doublet, triplet and quartet, respectively. Calculated bond lengths and bond angles of all metal complexes in higher-spin ground electronic states are in good agreement (about R2 = 0.97) with X-ray data. Additionally, the energies of the frontier MOs and frontier electron densities and also electrostatic potential of isostructural complexes have been analyzed by the DFT/6-311G(d,p) method. The water solubility and bioactivity of poorly soluble 3,5-dinitrobenzoic acid are enhanced by a preparation of three isostructural metal complexes and one polymorphic organic salt with participation of monoethanolamine and DFT study of metal complexes has been carried out.

中文翻译：

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通过单乙醇胺合成用于生物制药优化的 3,5-二硝基苯甲酸的三种混合配体金属配合物和一种有机盐：配合物的结构和 DFT 研究

最简单的苯甲酸衍生物显示出广泛的生物作用，主要是水溶性差。为了证明 3,5-二硝基苯甲酸 (DNBA) 同时增强水溶性和抗菌活性的可能性，研究了络合（盐形成和金属配位）方法。选择单乙醇胺（MEA）作为络合剂。合成了Cu、Ni、Co与DNBA和MEA的三种同晶型混合配体配合物以及一种多晶型有机盐，并通过元素分析、FTIR和X射线晶体学表征了其结构。水溶性的测量和抗微生物活性的测定证明铜混合配体络合物和有机盐的溶解度增加了大约四倍和八倍，同时生物活性增强。B3LYP/def2-TZVP 和 B3LYP/6-311G (d,p) 的 DFT 研究表明，Cu、Ni 和 Co 与 DNBA 和 MEA 的配合物分别具有高自旋基电子态，分别为双峰、三重峰和四重峰。高自旋基电子态中所有金属配合物的计算键长和键角与 X 射线数据非常吻合（约 R2 = 0.97）。此外，通过 DFT/6-311G(d,p) 方法分析了前沿 MO 的能量和前沿电子密度以及同构配合物的静电势。难溶性3的水溶性和生物活性，