Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700 032, India.
Inorg Chem. 2011 Nov 7;50(21):10693-702. doi: 10.1021/ic2011502. Epub 2011 Sep 26.
Tris(2-aminoethyl)amine (tren) based pentafluorophenyl-substituted tripodal L, tris[[(2,3,4,5,6-pentafluorobenzyl)amino]ethyl]amine receptor is synthesized in good yield and characterized by single crystal X-ray diffraction analysis. Detailed structural aspects of binding of different anionic guests toward L in its triprotonated form are examined thoroughly. Crystallographic results show binding of fluoride in the C(3v)-symmetric cavity of H(3)L where spherical anion fluoride is in tricoordinated geometry via (N-H)(+)···F interaction in the complex [H(3)L(F)]·F·2H(2)O, (3). In the case of complexes [H(3)L(OTs)]·OTs, (4) and [H(3)L(OTs)]·[NO(3)]·[OTs], (5), tetrahedral p-toluenesulphonate ion is engulfed in the cavity of H(3)L via (N-H)(+)···O interactions. Interestingly, complex [(H(3)L)(2)(SiF(6))]·BF(4)·CH(3)OH·H(2)O, (6) shows encapsulation of octahedral hexafluorosilicate in the dimeric capsular assembly of two H(3)L units, via a number of (N-H)(+)···F interactions. The kinetic parameters of L upon binding with different anions are evaluated using a potentiometric study in solution state. The potentiometric titration experiments in a polar protic methanol/water (1:1 v/v) binary solvent system show high affinity of the receptor toward more basic fluoride and acetate anions, with a lesser affinity for other inorganic anions (e.g., chloride, bromide, nitrate, sulfate, dihydrogenphosphate, and p-toluenesulphonate).
三(2-氨基乙基)胺（tren）基五氟苯基取代三脚架 L，三[[（2,3,4,5,6-五氟苄基）氨基]乙基]胺受体以高产率合成，并通过单晶 X 射线衍射分析进行了表征。详细研究了不同阴离子客体与 L 在其三质子化形式下结合的结构方面。晶体学结果表明，氟离子在 H(3)L的 C(3v)-对称腔内结合，其中球形阴离子氟通过（N-H）（+）···F 相互作用以三配位几何形状结合在复合物 [H(3)L(F)]·F·2H(2)O 中，（3）。在复合物 [H(3)L(OTs)]·OTs，（4）和 [H(3)L(OTs)]·[NO(3)]·[OTs]，（5）中，四棱甲苯磺酸根离子通过（N-H）（+）···O 相互作用被包裹在 H(3)L的腔内。有趣的是，复合物 [(H(3)L)(2)(SiF(6))]·BF(4)·CH(3)OH·H(2)O，（6）显示出六氟硅酸盐在两个 H(3)L单元的二聚胶囊组装中的包裹，通过许多（N-H）（+）···F 相互作用。通过在溶液状态下的电位研究评估了 L 与不同阴离子结合的动力学参数。在极性质子甲醇/水（1:1v/v）二元溶剂系统中的电位滴定实验表明，该受体对更碱性的氟化物和乙酸盐阴离子具有高亲和力，对其他无机阴离子（例如，氯化物、溴化物、硝酸盐、硫酸盐、二氢磷酸盐和对甲苯磺酸盐）的亲和力较低。
