Synthesis 2017; 49(02): 358-364
DOI: 10.1055/s-0036-1588659
paper
© Georg Thieme Verlag Stuttgart · New York

Redox Switchable Thianthrene Cavitands

Wen Jie Onga, Federico Bertanib, Enrico Dalcanaleb, Timothy M. Swager*a
  • aDepartment of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA   Email: tswager@mit.edu
  • bDepartment of Chemistry, University of Parma and INSTM RU, Parco Area delle Scienze 17/A, Parma 43124, Italy
Further Information

Publication History

Received: 26 October 2016

Accepted: 02 November 2016

Publication Date:
28 November 2016 (eFirst)

Abstract

A redox activated vase-to-kite conformational change is reported for a new resorcinarene-based cavitand appended with four quinoxaline-fused thianthrene units. In its neutral state, the thianthrene-containing cavitand was shown by 1H NMR to adopt a closed vase conformation. Upon oxidation the electrostatic repulsion among the thianthrene radical cations promotes a kite conformation in the thianthrene-containing cavitand. The addition of acid produced a shoulder feature below 300 nm in the cavitand’s UV-Vis spectrum that we have assigned to the vase-to-kite conformation change. UV-Vis spectroelectrochemical studies of the cavitand revealed a development of a similar shoulder peak consistent with the oxidation-induced vase-to-kite conformation change. To support that the shoulder peak is diagnostic for a vase-to-kite conformation change, a model molecule constituting a single quinoxaline wall of the cavitand was synthesized and studied. As expected UV-Vis spectroelectrochemical studies of the cavitand arm did not display a shoulder peak below 300 nm. The oxidation-induced vase-to-kite conformation is further confirmed by the distinctive upfield shift in 1H chemical shift of the methine signal.

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