Strong CH Hydrogen Bonds and Photoswitchable Chloride Regulation


Strong CH Hydrogen Bonds and Photoswitchable Chloride Regulation

Amar H. Flood

Chemistry Department, Indiana University, Bloomington, Indiana 47401, USA

Molecular recognition provides one way to monitor and regulate anions in their myriad roles in biology and the environment. Crucial to the design of receptors for these tasks is the exploration of bioinspired strategies that can provide synthetic control over structure for the ultimate modulation of function. To these ends, we have synthesized aryl-triazole based macrocycles and foldamers that utilize Cu(I)-catalyzed click chemistry to effect their ease of preparation. The macrocyclic receptors, termed triazolophanes, demonstrate extremely high anion affinities arising from the inherent pre-organization of eight CH hydrogen bond donors.

The anions are stabilized by surprisingly strong triazole CH hydrogen bonding. After quantifying these interactions with the help of theory and experiment (and examining other

CH donors along the way), inspiration from biology led us to design light-activated, anionbinding foldamers bearing azobenzene units. Taking advantage of the cis / trans photoisomerization of azobenzene, we demonstrate control over the stability of the folded structure providing a means to start regulating chloride concentrations in solution.