کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5278292 | 1503266 | 2009 | 5 صفحه PDF | دانلود رایگان |
We report the synthesis of a new water-soluble iminecalix[4]arene host 4c with a deep hydrophobic cavity. The negatively charged four carboxylate functions on the top of the cavity play a major role in the recognition of charged molecular species. The 1H NMR titration experiments revealed that host 4c binds with cationic (10-12) and neutral guests (6-9) in water with high binding constants in the order of 104-105Â Mâ1. Cationic guest 9 showed highest binding constant of 2.81Â ÃÂ 105Â Mâ1 with host 4c amongst all tested guests. Selectivity over anionic guests (13-17) is established by the presence of negative charges at the top of the deep hydrophobic cavity, as guests 15 and 17 were not recognized by host 4c. Neutral pyridine derivatives with hydrophobic chains at para positions showed high binding constants of 6.02Â ÃÂ 104-2.23Â ÃÂ 105Â Mâ1. The data obtained for the recognition of the guests by host 4c revealed that the ionic as well as the hydrophobic-hydrophobic interactions are crucial in the molecular recognition in aqueous medium.
Journal: Tetrahedron Letters - Volume 50, Issue 52, 30 December 2009, Pages 7346-7350