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).

High-resolution 13C n.m.r. spectroscopy and X-ray crystallography of complexes formed by NN′-dimethyl-1,7-diaza-4,10-dioxacyclododecane

Abstract: Results obtained from an X-ray crystal structure determination of the 1:1 complex formed between NN′-dimethyl-1,7-diaza-4,10-dioxacyclododecane (1) and benzylammonium thiocyanate and dynamic 13C n.m.r. spectroscopy in CD2Cl2 of the 1:1 complex formed between (1) and (S)-α-phenylethylammonium perchlorate vindicate the constitutional and configurational validity of two-point binding with syn stereochemistry between the host and guest species but indicate that conformational isomerism can occur within the host species of such complexes.

Isomerism in bicyclic diacetals. Part II. Bicyclic methylene diacetals in the galacto, arabino, and ribo series

Abstract: Studies of the acid-catalysed methylenation of tetritols with the galacto, arabino, and ribo configurations have led to the following observations: (i) dimethyl galactarate affords dimethyl 2,3:4,5- and 2,5:3,4-di-O-methylene-galactrate, (ii) methyl-D-arabinonate affords methyl 2,3:4,5-, 2,4:3,5-, and 2,5:3,4-di-O-methylene-D-arabinonate, and (iii) methyl D-ribonate affords methyl 2,4:3,5- and 2,5:3,4-di-O-methylene-D-ribonate. Vicinal coupling constant data obtained by 1H n.m.r. spectroscopy show that dimethyl 2,5:3,4-di-O-methylenegalactarate and methyl 2,5:3,4-di-O-arabinonate exist predominantly in gauche,gauche conformations in solution whereas the gauche,anti conformation is highly populated in solutions of methyl 2,5:3,4-di-O-methylene-D-ribonate. The relative stabilities of the constitutional isomers are discussed in terms of electronic effects associated with gauche oxygen–oxygen interactions in O–[graphic omitted]–O fragments as well as in terms of steric effects. There is no strong evidence to support the view that such gauche oxygen–oxygen interactions are an important stabilising feature in cis-fused 3,5,8,10-tetraoxabicyclo[5.3.0]decanes.

Isolation and X-ray crystal structure of a 2:1 complex between picric acid and dibenzo-24-crown-8; an example of a sandwich structure

Abstract: Despite the lack of strong intermolecular interactions in solution, picric acid (PicH) forms crystalline 2:1 complexes with both dibenzo-18-crown-6 (DB18C6) and dibenzo-24-crown-8 (DB24C8). An X-ray crystallographic study of 2PicH·DB24C8 reveals a continous layer structure comprising alternate PicH and DB24C8 molecules with stacking of the π-electron-deficient aromatic rings in the PicH molecules and the π-electron-rich aromatic rings in DB24C8 molecules.

Suit[4]ane

Abstract: Suitanes are two-component mechanically interlocked molecules in which one (torso) of the components, with several protruding limbs, is encompassed by another (suit) all-in-one component. This kind...

Concurrent Covalent and Supramolecular Polymerization.

Abstract: Covalent and supramolecular polymerizations, both of which offer their own unique advantages, have emerged as popular strategies for making artificial materials. Herein, we describe a concurrent covalent and supramolecular polymerization strategy—namely, one which utilizes 1) a bis-azide-functionalized diazaperopyrenium dication that undergoes polymeriation covalently with a bis-alkyne-functionalized biphenyl derivative in one dimension as a result of a rapid and efficient β-cyclodextrin(CD)-accelerated, cucurbit[6]uril(CB)-templated azide–alkyne cycloaddition, while 2) the aromatic core of the dication is able to dimerize in a criss-cross fashion by dint of π–π interactions, enabling simultaneous supramolecular assembly, resulting in an extended polymer network in an orthogonal dimension.

Fast parallel algorithms for short-range molecular dynamics

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.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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。

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

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

The Chemistry and Applications of Metal-Organic Frameworks

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.