42860-25-3Relevant academic research and scientific papers
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.
Self-Assembly and Molecular Recognition in Water: Tubular Stacking and Guest-Templated Discrete Assembly of Water-Soluble, Shape-Persistent Macrocycles
Wang, Qiuhua,Zhong, Yulong,Miller, Daniel P.,Lu, Xiaoxing,Tang, Quan,Lu, Zhong-Lin,Zurek, Eva,Liu, Rui,Gong, Bing
supporting information, p. 2915 - 2924 (2020/02/04)
Supramolecular chemistry in aqueous media is an area with great fundamental and practical significance. To examine the role of multiple noncovalent interactions in controlled assembling and binding behavior in water, the self-association of five water-soluble hexakis(m-phenylene ethynylene) (m-PE) macrocycles, along with the molecular recognition behavior of the resultant assemblies, is investigated with UV-vis, fluorescence, CD, and NMR spectroscopy, mass spectrometry, and computational studies. In contrast to their different extents of self-aggregation in organic solvents, all five macrocycles remain aggregated in water at concentrations down to the micromolar (μM) range. CD spectroscopy reveals that 1-F6 and 1-H6, two macrocycles carrying chiral side chains and capable of H-bonded self-association, assemble into tubular stacks. The tubular stacks serve as supramolecular hosts in water, as exemplified by the interaction of macrocycles 1-H6 and 2-H6 and guests G1 through G4, each having a rod-like oligo(p-phenylene ethynylene) (p-PE) segment flanked by two hydrophilic chains. Fluorescence and 1H NMR spectroscopy revealed the formation of kinetically stable, discrete assemblies upon mixing 2-H6 and a guest. The binding stoichiometry, determined with fluorescence, 1H NMR, and ESI-MS, reveals that the discrete assemblies are novel pseudorotaxanes, each containing a pair of identical guest molecules encased by a tubular stack. The two guest molecules define the number of macrocyclic molecules that comprise the host, which curbs the "infinite" stack growth, resulting in a tubular stack with a cylindrical pore tailoring the length of the p-PE segment of the bound guests. Each complex is stabilized by the action of multiple noncovalent forces including aromatic stacking, side-chain H-bonding, and van der Waals interactions. Thus, the interplay of multiple noncovalent forces aligns the molecules of macrocycles 1 and 2 into tubular stacks with cylindrical inner pores that, upon binding rod-like guests, lead to tight, discrete, and well-ordered tubular assemblies that are unprecedented in water.
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.
Dual protonophore-chitinase inhibitors dramatically affect O. Volvulus molting
Gooyit, Major,Tricoche, Nancy,Lustigman, Sara,Janda, Kim D.
, p. 5792 - 5799 (2014/08/05)
The L3-stage-specific chitinase OvCHT1 has been implicated in the development of Onchocerca volvulus, the causative agent of onchocerciasis. Closantel, a known anthelmintic drug, was previously discovered as a potent and specific OvCHT1 inhibitor. As closantel is also a known protonophore, we performed a simple scaffold modulation to map out the structural features that are relevant for its individual or dual biochemical roles. Furthermore, we present that either OvCHT1 inhibition or protonophoric activity was capable of affecting O. volvulus L3 molting and that the presence of both activities in a single molecule yielded more potent inhibition of the nematode's developmental process.
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.
Potent mGluR5 antagonists: Pyridyl and thiazolyl-ethynyl-3,5-disubstituted- phenyl series
Alagille, David,Dacosta, Herve,Chen, Yelin,Hemstapat, Kamondanai,Rodriguez, Alice,Baldwin, Ronald M.,Conn, Jeffrey P.,Tamagnan, Gilles D.
supporting information; experimental part, p. 3243 - 3247 (2011/07/07)
We report the synthesis of four series of 3,5-disubstituted-phenyl ligands targeting the metabotropic glutamate receptor subtype 5: (2-methylthiazol-4-yl) ethynyl (1a-j,), (6-methylpyridin-2-yl)ethynyl (2a-j), (5-methylpyridin-2-yl) ethynyl (3a-j,), and (pyridin-2-yl)ethynyl (4a-j,). The compounds were evaluated for antagonism of glutamate-mediated mobilization of internal calcium in an mGluR5 in vitro assay. All compounds were found to be full antagonists and exhibited low nanomolar to subnanomolar activity.
Flipping the switch on chloride concentrations with a light-active foldamer
Hua, Yuran,Flood, Amar H.
supporting information; experimental part, p. 12838 - 12840 (2010/11/05)
Here we demonstrate a bioinspired system where light stimulus is used to trigger the wavelength-dependent release and then reuptake of chloride ions in nonaqueous solutions. A chiral aryl-triazole foldamer with two azobenzene end groups has been synthesized to define a folded binding pocket for chloride ions that unfolds with UV light to liberate the chloride. The trans-dominated helical foldamer becomes less stable upon photoisomerization to the cis forms. Simultaneously, the observed binding affinity shows an ~10-fold reduction from K = 3000 M-1 (MeCN, 298 K). Control of chloride levels using light is demonstrated by switching the conductivity of an electrolyte solution up and down.
Double-decked molecular crescents
Lin, Li,Zhang, Jiaxin,Wu, Xiangxiang,Liang, Guoxing,He, Lan,Gong, Bing
supporting information; experimental part, p. 7361 - 7363 (2010/12/19)
Molecules with a defined crescent shape have been generated from the folding or covalent locking of curved structural components connected together via multiple covalent tethers.
Fluorination of alcohols and diols with a novel fluorous deoxy-fluorination reagent
Furuya, Tsukasa,Nomoto, Takashi,Fukuhara, Tsuyoshi,Hara, Shoji
experimental part, p. 348 - 353 (2009/12/03)
We prepared a novel fluorous deoxy-fluorination reagent N,N-diethyl-α,α-difluoro-[3,5-bis(1H,1H,2H,2H-perfluorodecyl)benzyl]amine (1b) from 3,5-diiodobenzoic acid (3b) via N,N-diethyl-3,5-bis(1H,1H,2H,2H-perfluorodecyl)benzamide (2b) in four steps and used it for the fluorination of alcohols and diols. After the fluorination reactions, the isolation of the products and recovery of 2b was performed by extraction with a fluorous/organic solvent system.
Halogen-magnesium exchange on unprotected aromatic and heteroaromatic carboxylic acids
Kopp, Felix,Wunderlich, Stefan,Knochel, Paul
, p. 2075 - 2077 (2008/02/09)
The magnesiation of halogenated aromatic and heteroaromatic carboxylic acids is accomplished by their treatment with MeMgCl in the presence of LiCl and subsequent reaction with i-PrMgCl·LiCl; the resulting double-magnesiated species react with a variety of electrophiles in up to 97% yield. The Royal Society of Chemistry.
