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).

Proton Conduction in Tröger’s Base-Linked Poly(crown ether)s

Abstract: Exactly 50 years ago, the ground-breaking discovery of dibenzo[18]crown-6 (DB18C6) by Charles Pedersen led to the use of DB18C6 as a receptor in supramolecular chemistry and a host in host–guest chemistry. We have demonstrated proton conductivity in Troger’s base-linked polymers through hydrogen-bonded networks formed from adsorbed water molecules on the oxygen atoms of DB18C6 under humid conditions. Troger’s base-linked polymers—poly(TBL-DB18C6)-t and poly(TBL-DB18C6)-c—synthesized by the in situ alkylation and cyclization of either trans- or cis-di(aminobenzo) [18]crown-6 at room temperature have been isolated as high-molecular-weight polymers. The macromolecular structures of the isomeric poly(TBL-DB18C6)s have been established by spectroscopic techniques and size-exclusion chromatography. The excellent solubility of these polymers in chloroform allows the formation of freestanding membranes, which are thermally stable and also show stability under aqueous conditions. The hydrophilic nature of the DB18...

Thiamacrocyclic chemistry: Synthesis of a novel oxadithiacrown and its copper iodide complex

Abstract: A mixed oxa–thia macrocycle incorporating a rigid ‘horseshoe-shaped’ aromatic moiety, 1,11,21-trioxa-8,14-dithia[2,9,2]paracyclophane, L, has been synthesised. The molecular structures of L and of its copper iodide complex have been determined by single-crystal X-ray diffraction methods. There are two independent conformations observed in the solid state for the macrocycle, L. Its copper iodide complex [Cu 2 I 2 (L)]·1.25MeCN, crystallises, in a 2∶1 metal∶crown ratio, as a one-dimensional infinite array of cubane-like units consisting of four copper atoms, four iodine atoms and four sulfur atoms from four different macrocycles.

Complex formation between dibenzo-3n-crown-n ethers and the diquat dication

Abstract: An X-ray crystallographic investigation of the complex between the diquat dication and dibenzo-30-crown-10, [Diquat,DB30C10][PF6]2, reveals gross structural features for host–guest complexes (I) and (II) in which weak [C–H ⋯ O]hydrogen bonding and charge transfer are the major components of host–guest binding; these same components are also responsible for the formation of stable and orderde 1 : 1 solution complexes between dibenzo-3n-crown-n(n 9–12) and diquat bis(hexafluorophosphate)(2).

Polyvalent interactions in unnatural recognition processes.

Abstract: The synthesis of two cluster compounds, one containing six secondary dialkylammonium ion centers and the other possessing six benzo-m-phenylene[25]crown-8 (BMP25C8) macrocycles, both appended to hexakis(thiophenyl)benzene cores, is described. The binding of these clusters with complementary mono- and divalent ligands is investigated with NMR spectroscopy to probe polyvalency in these unnatural recognition systems. The ability of the two different families of clusters to bind complementary monovalent ligands is compared with that of the monovalent receptor pair, namely the dibenzylammonium ion and BMP25C8. This comparison is made possible by determining an average association constant (KAVE) for the binding of each recognition site on the cluster with the corresponding monovalent ligand. We have found that the clustering of recognition sites together in one molecule is detrimental to their individual abilities to bind monovalent ligands. In the case of the polyvalent interaction between the hexakisBMP25C8 ...

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.