Indole-based synthetic receptors which bind anions by multiple hydrogen bonds in organic solvents have been prepared. The biindole scaffold bearing two good hydrogen bond donors of indole NHs has been used as a molecular building block to construct the receptors. Incorporation of more hydrogen bond donors or acceptors increases the binding strength and selectivity toward a specific ion. Two macrocycles having different sizes of the internal cavities have been also synthesized, and their binding properties have been compared. Two macrocycles display distinct binding modes with polyatomic anions such as azide, as un-equivocally proven by X-ray crystal structures. Finally, a series of oligoindoles containing four, six, and eight indoles have been prepared by Sonogashira reactions. The oligoindoles fold into helical structures upon binding with chloride. The binding affinities of the oligoindoles with chloride increase with increasing of the chain length, which provides an additional evidence for helical folding of the complexes.
Bibliographical noteFunding Information:
This work was financially supported by the Center for Bioactive Molecular Hybrids (CBMH) and Korea Research Foundation Grant (KRF-2004-041-C00215). J.-m.S., M.K.C., N.-K.K., and U.I.K. acknowledge the fellowship of the BK 21 program from the Ministry of Education and Human Resources Development.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)