Işiklan Muhammet, Saeed Musabbir A, Pramanik Avijit, Wong Bryan M, Fronczek Frank R, Hossain Alamgir
Department of Chemistry and Biochemistry, Jackson State University, Jackson, Mississippi 39217.
Cryst Growth Des. 2011 Apr 6;11(4):959-963. doi: 10.1021/cg2001859.
A thiophene-based tripodal receptor has been synthesized and its complexes with nitrate and iodide have determined by single-crystal X-ray analysis. In the nitrate complex, one nitrate is encapsulated in a selective orientation forming a C(3) symmetric complex, which is bonded to three protonated secondary amines with six NH···O bonds. The anion is coordinated in a plane perpendicular to the principal rotation axis passing through the tertiary nitrogen of the receptor and the nitrogen of the encapsulated nitrate. High-level DFT calculations support the crystallographic results demonstrating that an adduct with trigonal binding of three oxygen atoms is more stable than that of one oxygen atom of the encapsulate nitrate. On the other hand, in the structure of the iodide complex, all three iodides lie outside the cavity. (1)H NMR titration studies indicate that the receptor forms a 1:1 complex with nitrate with a binding constant of K = 315 M(-1) in chloroform, showing a moderate selectivity over halides and perchlorate.
合成了一种基于噻吩的三脚架型受体，并通过单晶X射线分析确定了其与硝酸盐和碘化物的配合物。在硝酸盐配合物中，一个硝酸盐以选择性取向被包封，形成一个C(3)对称配合物，该配合物通过六个NH···O键与三个质子化仲胺键合。阴离子在垂直于穿过受体叔氮和包封硝酸盐氮的主旋转轴的平面内配位。高水平的DFT计算支持晶体学结果，表明具有三个氧原子三角结合的加合物比包封硝酸盐的一个氧原子的加合物更稳定。另一方面，在碘化物配合物的结构中，所有三个碘化物都位于空腔之外。(1)H NMR滴定研究表明，该受体在氯仿中与硝酸盐形成1:1配合物，结合常数K = 315 M(-1)，对卤化物和高氯酸盐表现出中等选择性。
