Constructing bridged multifunctional calixarenes by intramolecular indole coupling

Boris Bolshchikov, Sergey Volkov, Daria Sokolova, Alexander Gorbunov, Alina Serebryannikova, Igor Gloriozov, Dmitry Cheshkov, Stanislav Bezzubov, Wen Sheng Chung, Vladimir Kovalev, Ivan Vatsouro*

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

2,2′-Bisindole units are suggested as new bridging motifs which can be easily created at calixarene cores. In TFA solutions, calix[4]arenes having pairs of indole groups originating from tryptamine or tryptophan residues are converted selectively into macrocycles bridged by indolylindoline moieties. The latter are easily transformed into fluorescent 2,2′-bisindole bridges upon oxidation. The coupling/oxidation sequence works fine at bridging the cavities of the cone and 1,3-alternate (thia)calix[4]arenes in their distal positions. Ester groups, triazole units and crown ether loops, which are practically important functionalities in calixarene chemistry, are compatible with the bridging strategy thus making available diverse calixarene-based hosts comprising novel features provided by the 2,2′-bisindole bridges. Of them the abilities to self-assembly and to bind anions through multiple hydrogen bonds were observed by X-ray crystallography, fluorescence measurements, and NMR experiments. When combined with a cation-binding site, the 2,2′-bisindole units can turn the calixarene molecules into heteroditopic receptors being able to stabilize the anionic parts of the ion pairs. This feature was assessed by using the 1,3-alternate calix[4]arene having the 2,2′-bisindole bridge and the crown-5-ether loop which was found to form neutral complexes with potassium acetate or potassium benzoate.

Original languageEnglish
Pages (from-to)3327-3341
Number of pages15
JournalOrganic Chemistry Frontiers
Volume6
Issue number19
DOIs
StatePublished - 7 Oct 2019

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    Bolshchikov, B., Volkov, S., Sokolova, D., Gorbunov, A., Serebryannikova, A., Gloriozov, I., Cheshkov, D., Bezzubov, S., Chung, W. S., Kovalev, V., & Vatsouro, I. (2019). Constructing bridged multifunctional calixarenes by intramolecular indole coupling. Organic Chemistry Frontiers, 6(19), 3327-3341. https://doi.org/10.1039/c9qo00859d