A C-3v-Symmetric Tripodal Urea Receptor for Anions and Ion Pairs: Formation of Dimeric Capsular Assemblies of the Receptor during Anion and Ion Pair Coordination

作者：Basu Arghya; Das Gopal^*

来源：Journal of Organic Chemistry, 2014, 79(6): 2647-2656.

DOI：10.1021/jo500102e

A new C-3v-symmetric urea-based heteroditopic tripodal receptor capable of recognizing both anions and ion pairs was designed, synthesized, and characterized. The protonated receptor forms a sulfate complex which encapsulates a single DMF in the tripodal cavity of the receptor. However, the SO42- anion is located outside the tripodal cavity and is stabilized by N-H center dot center dot center dot O hydrogen bonds from the urea functions of four receptor cations. With TBAHSO(4) the receptor forms a contact ion pair complex, where both the TBA(+) and SO42- groups are pseudoencapsulated in the tripodal cavity of the protonated receptor. Significantly, the receptor forms a charge-separated polymeric ion pair complex with K+ and HPO42- via formation of a dimeric capsular assembly of the receptor, in which three K+ encapsulated dimeric capsular assemblies interdigitate to form a precise cavity that further encapsulates HPO42-. The receptor also forms an anion complex with CO32- via formation of dimeric capsular self-assembly of the receptor. Solution-state binding studies of the receptor with oxyanions have also been carried out by H-1 NMR titration experiments, which show the oxyanion binding trend HCO3- > H2PO4- > HSO4-, whereas no binding with NO3- and ClO4- anions is observed.

• 出版日期2014-3-21