Portis Bobby, Mirchi Ali, Emami Khansari Maryam, Pramanik Avijit, Johnson Corey R, Powell Douglas R, Leszczynski Jerzy, Hossain Md Alamgir
Department of Chemistry and Biochemistry, Jackson State University, Jackson, Mississippi 39217, United States.
Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States.
ACS Omega. 2017 Sep 30;2(9):5840-5849. doi: 10.1021/acsomega.7b01115. Epub 2017 Sep 18.
The anion-binding properties of two tripodal-based hexaureas appended with the -nitrophenyl () and pentafluorophenyl () groups have been studied both experimentally and theoretically, showing strong affinities for sulfate over other inorganic oxoanions such as hydrogen sulfate, dihydrogen phosphate, bicarbonate, nitrate, and perchlorate. The structural analysis of the sulfate complex with reveals that the receptor organizes all urea-binding sites toward the cavity at precise orientations around a tetrahedral sulfate anion to form an ideal -symmetric sulfate complex that is stabilized by 12 hydrogen-bonding interactions. The receptor and the encapsulated sulfate are located on the threefold axis passing through the bridgehead nitrogen of and the sulfur atom of the anionic guest. The high-level density functional theory calculations support the crystallographic results, demonstrating that the -symmetric conformation of the sulfate complex is achieved due to the complementary NH···O between the receptor and sulfate.
对两个分别带有对硝基苯基（）和五氟苯基（）基团的三脚架型六脲的阴离子结合特性进行了实验和理论研究，结果表明其对硫酸根的亲和力强于其他无机含氧阴离子，如硫酸氢根、磷酸二氢根、碳酸氢根、硝酸根和高氯酸根。与硫酸根形成的配合物的结构分析表明，该受体将所有脲结合位点以精确的取向围绕四面体硫酸根阴离子朝向空腔排列，形成一个理想的对称硫酸根配合物，该配合物通过12个氢键相互作用得以稳定。受体和被包封的硫酸根位于通过的桥头氮和阴离子客体的硫原子的三重轴上。高水平密度泛函理论计算支持了晶体学结果，表明硫酸根配合物的对称构象是由于受体与硫酸根之间互补的NH···O作用而实现的。
