Trimodal Control of Ion‐Transport Activity on Cyclo‐oligo‐(1→6)‐β‐D‐glucosamine‐Based Artificial Ion‐Transport Systems. Issue 48 (8th October 2015) - Roy, Arundhati
Abstract: Cyclo‐oligo‐(1→6)‐β‐D ‐glucosamines functionalized with hydrophobic tails are reported as a new class of transmembrane ion‐transport system. These macrocycles with hydrophilic cavities were introduced as an alternative to cyclodextrins, which are supramolecular systems with hydrophobic cavities. The transport activities of these glycoconjugates were manipulated by altering the oligomericity of the macrocycles, as well as the length and number of attached tails. 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. Abstract : Polar preferences : Glycoconjugates based on cyclo‐oligo‐(1→6)‐β‐D ‐glucosamines (GA) are interesting systems for transmembrane ion transport (see figure). The transport activity of this system can be modulated by varying the oligomericity of the ring, along with the length and number of tails connected to each macrocycle. The polar cavity of this macrocyclic system allows preferential permeation of Cl − ions.