Chenfeng ke

Publications (18) View all

• Source

  Available from: Zhichang Liu

  Article: Synthesis and Solution-State Dynamics of Donor-Acceptor Oligorotaxane Foldamers

  Zhixue Zhu, Carson J Bruns, Hao Li, Juying Lei, Chenfeng Ke, Zhichang Liu, Saman Shafaie, Howard colquhoun, J. Fraser Stoddart
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  ABSTRACT: We describe in detail a strategy for creating foldamers in which interactions between mechanically interlocked components dictate the single-molecule assembly of a folded secondary structure. This unique folding motif is based on a flexible polyether dumbbell bearing 1,5-dioxynaphthalene (DNP) donors, which folds its way through a series of cyclobis(paraquat-p-phenylene) (CBPQT4+) acceptor rings in a serpentine fashion to enable extended donor-acceptor (D-A) stacking between DNP and the electron-poor 4,4'-bipyridinium (BIPY2+) units in CBPQT4+. These oligorotaxanes can be prepared in a wide range of sizes, with molecular weights up to >15000 Da, on account of novel one-pot reactions we developed to generate the necessary oligo-DNP precursors. The product distributions from the final kinetically-controlled stoppering reactions are highly biased towards oligorotaxanes in which approximately half of the DNP units are encircled by rings, a fact which can be rationalized if the dominant solution-state struc
  Chemical science (Royal Society of Chemistry) 02/2013; 4:1470-1483. · 7.53 Impact Factor
• Article: Mechanical Bond-Induced Radical Stabilization.

  Hao Li, Zhixue Zhu, Albert C Fahrenbach, Brett M Savoie, Chenfeng Ke, Jonathan C Barnes, Juying Lei, Yanli Zhao, Laura Lilley, Tobin J Marks, Mark A Ratner, J Fraser Stoddart
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  ABSTRACT: A homologous series of [2]rotaxanes, in which cyclobis(paraquat-p-phenylene) (CBPQT4+) serves as the ring component, while the dumbbell components all contain single 4,4'-bipyridinium (BIPY2+) units centrally located in the midst of oligomethylene chains of varying lengths, have been synthesized by taking advantage of radical templation and copper-free azide-alkyne 1,3-dipolar cycloadditions in the formation of their stoppers. Cyclic voltammetry, UV/Vis spectroscopy and mass spectrometry reveal that the BIPY•+ radical cations in this series of [2]rotaxanes are stabilized against oxidation, both electrochemically and by atmospheric oxygen. The enforced proximity between the BIPY2+ units in the ring and dumbbell components gives rise to enhanced Coulombic repulsion, destabilizing the ground-state co-conformations of the fully oxidized forms of these [2]rotaxanes. The smallest [2]rotaxane with only three methylene groups on each side of its dumbbell component is found to exist under ambient conditions in a monoradical state, a situation which does not persist in acetonitrile solution at least in the case of its longer analogues. 1H NMR Spectroscopy reveals that the activation energy barriers to the shuttling of the CBPQT4+ rings over the BIPY2+ units in the dumbbells rise linearly with increasing oligomethylene chain lengths across the series of [2]rotaxanes. These findings provide a new way of producing highly stabilized BIPY•+ radical cations and open up more opportunities to use stable organic radicals as building blocks for the construction of paramagnetic materials and conductive molecular electronic devices.
  Journal of the American Chemical Society 11/2012; · 9.91 Impact Factor
• Article: Quantitative Emergence of Hetero[4]rotaxanes by Template-Directed Click Chemistry.

  Chenfeng Ke, Ronald A Smaldone, Takashi Kikuchi, Hao Li, Anthony P Davis, J Fraser Stoddart
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  ABSTRACT: In one fell swoop, polyrotaxanes comprising up to 64 rings can be synthesized as a result of cucurbit[6]uril-templated 1,3-dipolar azide-alkyne cycloadditions accelerated in the presence of cyclodextrins as a consequence of self-sorting and positive cooperativity, brought about by hydrogen bonding. Mixing six components in one pot affords a hetero[4]rotaxane in one minute in quantitative yield.
  Angewandte Chemie International Edition 09/2012; · 13.45 Impact Factor
• Article: A simple and accessible synthetic lectin for glucose recognition and sensing.

  Chenfeng Ke, Harry Destecroix, Matthew P Crump, Anthony P Davis
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  ABSTRACT: Binding carbohydrates from water is a difficult task, even for the natural carbohydrate-binding proteins known as lectins. The design of synthetic lectin mimics is correspondingly challenging, especially if good selectivities are required. In previous work we showed that success is possible, but only for complex polycyclic architectures that require lengthy and low-yielding syntheses; for example, one glucose-selective system was made in 21 steps and only 0.1% overall yield. Here we report the discovery of a simple monocyclic host that matches the earlier designs, but is far more accessible as it is prepared in just five steps and 23% overall yield. The new synthetic lectin binds glucose with excellent selectivity versus other common monosaccharides (for example, ~50:1 versus galactose) and sufficient affinity for glucose sensing at the concentrations found in blood. It also features a built-in signalling system in the form of strong and guest-dependent fluorescence emission. The effectiveness and simplicity of this molecule suggests the potential for development into a new methodology for practical glucose monitoring.
  Nature Chemistry 08/2012; 4(9):718-23. · 20.52 Impact Factor
• Article: High-affinity disaccharide binding by tricyclic synthetic lectins.

  Bunyarithi Sookcharoenpinyo, Emmanuel Klein, Yann Ferrand, D Barney Walker, Peter R Brotherhood, Chenfeng Ke, Matthew P Crump, Anthony P Davis
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  ABSTRACT: Stay flexible: Rigid preorganization is not always the best approach to molecular recognition. Unlike previous synthetic lectins, new receptors were synthesized that possess conformational freedom which allows hydrophobically driven collapse of the cavity. Nonetheless, they bind their carbohydrate targets in water with ground-breaking affinities (up to 4500 M(-1) for methyl cellobioside, R=Me) and selectivities.
  Angewandte Chemie International Edition 03/2012; 51(19):4586-90. · 13.45 Impact Factor