Synthetic ionophores. Part 18: Ag+ selective trithiabenzena- and dithiabenzenapyridinacyclophanes 1
作者:Subodh Kumar、Maninder Singh Hundal、Geeta Hundal、Palwinder Singh、Vandana Bhalla、Harjit Singh
DOI:10.1039/a706861a
日期:——
The phase transfer catalysed nucleophilic displacement of 1,3-bis(bromomethyl)benzene, 2-methoxy-5-methyl-1,3-bis(bromomethyl)benzene (2) and 1,4-bis(bromomethyl)benzene with 2-mercaptoethanol gives the respective diols 3, 4 and 12 (80–85%), which undergo intermolecular cyclodehydrochlorination with thiodiglycolyl dichloride and pyridine-2,6-dicarbonyl dichloride·HCl to provide m-phenylene (7–10) and p-phenylene (13–14) based crownophanes. The single crystal X-ray structures of crownophanes 8 and 13 and their NMR studies show that the m-phenylene and p-phenylene rings remain in plane and perpendicular to the macrocyclic ring both in solution and solid phases. These crownophanes offer three soft coordinating sites (3 × S or 2 × S and 1 N) conducive to complexation with Ag+ and the steric restrictions imposed by m- and p-phenylene rings restrict 2∶1 (L∶M) sandwich complexation required for complexation with the borderline soft Pb2+ cation. The crownophanes 7 and 9 extract Ag+ 172 and 602 times, respectively, more than Pb2+.
在相转移催化下,1,3-双(溴甲基)苯、2-甲氧基-5-甲基-1,3-双(溴甲基)苯(2)和 1,4-双(溴甲基)苯与 2-巯基乙醇发生亲核置换反应,生成相应的二元醇 3、4 和 12(80-85%)、4 和 12(80-85%),它们与硫代二甘氨酰二氯和吡啶-2,6-二羰基二氯-HCl 发生分子间环脱氢氯化反应,生成间苯(7-10)和对苯(13-14)基冠烷。冠烷 8 和冠烷 13 的单晶 X 射线结构及其核磁共振研究表明,间苯二酚环和对苯二酚环在溶液和固相中都保持在平面上,并垂直于大环。这些冠烷提供了三个有利于与 Ag+ 复配的软配位位点(3 × S 或 2 × S 和 1 N),而间苯环和对苯环施加的立体限制则限制了与边缘软性 Pb2+ 阳离子复配所需的 2∶1 (L∶M)夹层复配。冠烷 7 和 9 对 Ag+ 的萃取率分别是 Pb2+ 的 172 倍和 602 倍。