42860-25-3Relevant articles and documents
Hexakis(m-phenylene ethynylene) Macrocycles with Multiple H-Bonding Side Chains and Modified Cavities: Altered Stacking Strength and Persistent Tubular Assembly
Zhong, Yulong,Wang, Qiuhua,Yang, Yi,Lu, Zhonglin,He, Lan,Gong, Bing
, p. 2094 - 2097 (2016)
Hexakis(m-phenylene ethynylene) macrocycles 1 bearing multiple hydrogen-bonding side chains and containing inner cavities modified with different functional groups are synthesized based on Pd-catalyzed (Sonogashira) coupling of monomeric building blocks to trimeric precursors that are recombined and coupled to give macrocycles with different substitution patterns of inward-pointing groups. Examining four representative macrocycles indicates that they all undergo the same helical tubular assembly previously observed for macrocycle 1a but with different stacking strengths.
Persistent Organic Nanopores Amenable to Structural and Functional Tuning
Wei, Xiaoxi,Zhang, Guoqing,Shen, Yi,Zhong, Yulong,Liu, Rui,Yang, Na,Al-Mkhaizim, Fayez Y.,Kline, Mark A.,He, Lan,Li, Minfeng,Lu, Zhong-Lin,Shao, Zhifeng,Gong, Bing
supporting information, p. 2749 - 2754 (2016/03/12)
Rigid macrocycles 2, which share a hybrid backbone and the same set of side chains while having inner cavities with different inward-pointing functional groups, undergo similar nanotubular assembly as indicated by multiple techniques including 1H NMR, fluorescence spectroscopy, and atomic force microscopy. The formation of tubular assemblies containing subnanometer pores is also attested by the different transmembrane ion-transport behavior observed for these macrocycles. Vesicle-based stopped-flow kinetic assay and single-channel electrophysiology with planar lipid bilayers show that the presence of an inward-pointing functional (X) group in the inner cavity of a macrocyclic building block exerts a major influence on the transmembrane ion-transporting preference of the corresponding self-assembling pore. Self-assembling pores with inward-pointing amino and methyl groups possess the surprising and remarkable capability of rejecting protons but are conducive to transporting larger ions. The inward-pointing groups also resulted in transmembrane pores with a different extent of positive electrostatic potentials, leading to channels having different preferences for transporting chloride ion. Results from this work demonstrate that synthetic modification at the molecular level can profoundly impact the property of otherwise structurally persistent supramolecular assemblies, with both expected tunability and suprisingly unusual behavior.
β-sheet-like hydrogen bonds interlock the helical turns of a photoswitchable foldamer to enhance the binding and release of chloride
Lee, Semin,Hua, Yuran,Flood, Amar H.
, p. 8383 - 8396 (2015/03/18)
Inspired by halorhodopsins use of photoisomerization to regulate chloride, aryltriazole-based foldamers have been created to "catch and release" chloride ions upon light irradiation of end-appended azobenzenes. The proposed mode of stabilization exploits a β-sheet-like hydrogen-bonding array to cooperatively interlock the ends of a foldamer together with its helical core. We find that the hydrogen-bonding array has a greater influence on stabilizing the helix than the π-stacked seam under the conditions examined (50:50 MeCN/THF). Thus, we show how it is possible to enhance the difference between Cl- binding and release using light-dependent control over the foldamers degree of helix stabilization. Making and breaking three π-π contacts with light caused an 8-fold change in chloride affinity (40 300 M-1 ? 5000 M-1), five π-π contacts produced a 17-fold change (126 000 M-1 ? 7400 M-1), and strategically located hydrogen-bonding units enabled a greater 84-fold differential (970 000 M-1 ? 11 600 M-1). The improved performances were attributed to stepwise increases in the preorganization of the binding pocket that catches chloride while leaving the cis states with just one π-π contact relatively unchanged.
