Published in

American Chemical Society, Journal of the American Chemical Society, 2(137), p. 876-885, 2015

DOI: 10.1021/ja5111305

Links

Tools

Export citation

Search in Google Scholar

Folding of Oligoviologens Induced by Radical–Radical Interactions

This paper is available in a repository.
This paper is available in a repository.

Full text: Download

Red circle
Preprint: archiving forbidden
Orange circle
Postprint: archiving restricted
Red circle
Published version: archiving forbidden
Data provided by SHERPA/RoMEO

Abstract

We report the synthesis of a series of homologous oligoviologens in which different numbers of 4,4'-bipyridinium (BIPY2+) subunits are linked by p-xylylene bridges, as a prelude to investigating how their radical cationic forms self-assemble both in solution and in the solid state. The strong radical-radical interactions, which exist between the radical cationic forms of the BIPY2+ units ? namely, BIPY?+ ? in these oligoviologens, induces intra- or intermolecular folding of these homologues. UV/Vis/NIR Spectroscopic studies and DFT quantum mechanics indicate that the folding of the shorter oligoviologens is dominated by intermolecular radical-radical interactions. In addition to intermolecular interactions, strong intramolecular radical-radical interactions, which give rise to an NIR absorption band at 900 nm, tend to play a crucial role in governing the folding of the longer oligoviologens. The solid-state superstructure of the oligoviologen with three BIPY2+ units reveals that two intertwining chains fold together to form a dimer, stabilized by intermolecular radical-radical interactions. These dimers continue to stack in an infinite column through intermolecular radical-radical interactions between them. This research features an artificial biomimetic system which sustains delicate secondary and tertiary structures, reminiscent of those present in nucleic acids and proteins.