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J. Fraser Stoddart

Bio: J. Fraser Stoddart is an academic researcher from Northwestern University. The author has contributed to research in topics: Catenane & Supramolecular chemistry. The author has an hindex of 147, co-authored 1239 publications receiving 96083 citations. Previous affiliations of J. Fraser Stoddart include Zhejiang University & Northwest University (United States).


Papers
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Journal ArticleDOI
TL;DR: In this paper, the electron transfer around the core of C60 has been achieved by electron transfer centered on π-dimerizable viologen subunits located in a restricted region of space.
Abstract: Molecular reorganization around the core of C60 has been achieved by electron transfer centered on π-dimerizable viologen subunits located in a restricted region of space. Fullerene C60 hexaadducts, featuring 12 viologen subunits, have been prepared by using copper-mediated Huisgen 1,3-dipolar cycloaddition of azides with alkynes. Detailed electrochemical studies, supported by UV-Vis and EPR spectroscopic analyses, demonstrate that the linkers bearing the viologen subunits attached to specific positions around the all-carbon sphere, allow the formation of six intramolecular π-dimers. Theoretical calculations reveal that the close proximity of the orbitals of the viologen subunits attached to the C60 facilitate the π-dimerization of the bis-radical species. These investigations support the fact that the motion of discrete peripheral groups oriented around the all-carbon sphere of C60 can be controlled electrochemically using noncovalent reversible interactions.

44 citations

Journal ArticleDOI
TL;DR: In this article, 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, is used to enable extended donor-acceptor (D-A) stacking between DNP and the electron-poor 4,4′-bipyridinium (BIPY2+) units.
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 >15 000 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 structures of the pseudorotaxane precursors reflect the solid-state superstructures of analogous compounds, which express 50% recognition site occupancy because of their proclivity to pack into continuous D–A–D–A stacks. The presence of well-defined folded structures in solution have been confirmed by 1H NMR spectroscopy in CD3CN. Moreover, we discovered an empirical selection rule forbidding CBPQT4+ rings to occupy adjacent DNP sites, which elegantly explains both the product distributions and the 1H NMR spectra. Depending on their adherence to this selection rule, all of the oligorotaxanes belong to one of three families: whereas ‘Confused’ oligorotaxanes adopt multiple translational isomers that satisfy the rule and ‘Frustrated’ species cannot obey it at all, members of the ‘Happy’ family each express only one rule-compliant ‘Goldilocks’ isomer. The NMR spectra of these oligorotaxanes also shed light on their dynamics; rapid 180° rotations of DNP units cause pairs of heterotopic BIPY2+ protons in the accompanying CBPQT4+ rings to exchange sites, giving rise to time-averaged signals. This process, which we term ‘superrotation’, will apply much more generally to other mechanically interlocked systems.

44 citations

Journal ArticleDOI
TL;DR: In this article, an aniline-bearing pseudorotaxane was synthesized by the hydrogen bond-driven threading of a dibenzylammonium filament through the cavity of the macrocyclic polyether Dibenzo[24]crown-8.

44 citations

Journal ArticleDOI
TL;DR: A stable Tetrathiafulvalene (TTFV) functionalized self-assembled monolayer has been fabricated from compound 3 as discussed by the authors, where the electrochemical adjustment of the guest properties of the TTF moiety of this unit has facilitated the development of surfaces in which the 30 state forms a pseudorotaxane with the electron deficient macrocyclic host cyclobis(paraquat-p-phenylene) 1.5-dinaphtho[38]crown-10 2.
Abstract: A stable tetrathiafulvalene (TTF) functionalized self-assembled monolayer has been fabricated from compound 3. The electrochemical adjustment of the guest properties of the TTF moiety of this unit has facilitated the development of surfaces in which the 30 state forms a pseudorotaxane with the electron deficient macrocyclic host cyclobis(paraquat-p-phenylene) 1, and the electrochemically generated dicationic state 32+ forms a pseudorotaxane with the electron rich macrocyclic host 1,5-dinaphtho[38]crown-10 2.

43 citations

Journal ArticleDOI
TL;DR: Starting from a chiral building block--α-cyclodextrin--and rubidium salts, the crystallization of a complex of chiral helices, which constitute a "green" porous coordination polymer, has been realized.

43 citations


Cited by
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01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: A review of gold nanoparticles can be found in this article, where the most stable metal nanoparticles, called gold colloids (AuNPs), have been used for catalysis and biology applications.
Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

11,752 citations

Journal ArticleDOI
30 Aug 2013-Science
TL;DR: Metal-organic frameworks are porous materials that have potential for applications such as gas storage and separation, as well as catalysis, and methods are being developed for making nanocrystals and supercrystals of MOFs for their incorporation into devices.
Abstract: Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

10,934 citations