1.D.171. The Cyclo-Oligo-(1 6)-beta-D-Glucosamine-based Artificial Anion Channel (COGAAC) Family Unimolecular ion channels have been designed by functionalizing a new type of cyclic oligosaccharides, cyclo-oligo-(1 → 6)-β-d-glucosamines, with pentabutylene glycol chains. Their ion transporting activity was tuned by varying oligomericity. A halide selectivity sequence, Cl^- > Br^- > I^-, was transported (Saha et al. 2014). Hydrophobic tails of 3 different sizes were synthesized and coupled with each glucosamine scaffold through the amide linkage to obtain 18 derivatives. The ion-transport activity increased from di- to tetrameric glucosamine macrocycles, but decreased further when flexible pentameric glucosamine was introduced. The ion-transport activity also increased with increasing length of attached linkers. For a fixed length of linkers, the transport activity decreased when the number of such tails was reduced. All glycoconjugates displayed a uniform anion-selectivity sequence: Cl^- >Br^- >I^-. From theoretical studies, hydrogen bonding between the macrocycle backbone and the anion bridged through water molecules was observed (Roy et al. 2015).
References:
Roy, A., T. Saha, M.L. Gening, D.V. Titov, A.G. Gerbst, Y.E. Tsvetkov, N.E. Nifantiev, and P. Talukdar. (2015). Trimodal Control of Ion-Transport Activity on Cyclo-oligo-(1→6)-β-D-glucosamine-Based Artificial Ion-Transport Systems. Chemistry 21: 17445-17452.
Saha, T., A. Roy, M.L. Gening, D.V. Titov, A.G. Gerbst, Y.E. Tsvetkov, N.E. Nifantiev, and P. Talukdar. (2014). Cyclo-oligo-(1 → 6)-β-D-glucosamine based artificial channels for tunable transmembrane ion transport. Chem Commun (Camb) 50: 5514-5516.