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).

Photoinduced electron flow in a self-assembling supramolecular extension cable.

Abstract: We report the design, bottom-up construction, characterization, and operation of a supramolecular system capable of mimicking the function played by a macroscopic electrical extension cable. The system is made up of a light-powered electron source, an electron drain, and a cable as the molecular components programmed to self-assemble by means of two distinct plug/socket junctions. Such connections are reversible and can be operated independently by orthogonal chemical inputs. In the source–connector–drain supermolecule, photoinduced electron transfer from source to drain occurs, and it can be switched off by dual-mode chemically controlled disassembling of the molecular components.

The self-assembly of a highly ordered [2]catenane

Abstract: Template-directed synthesis has been used to construct a [2]catenane in which the two molecular components, the cyclobis(paraquat-p-phenylene) tetracation and 1,5-dinaphtho-38-crown-10, are found to be ordered non-covalently with respect to each other in both the solid (by X-ray crystallography) and solution (by NMR spectroscopy) states and to influence each other to the extent of establishing electrochemical gradients for the stepwise one electron reductions of the two paraquat units.

Probing Distance Dependent Charge-Transfer Character in Excimers of Extended Viologen Cyclophanes Using Femtosecond Vibrational Spectroscopy.

Abstract: Facile exciton transport within ordered assemblies of π-stacked chromophores is essential for developing molecular photonic and electronic materials. Excimer states having variable charge transfer (CT) character are frequently implicated as promoting or inhibiting exciton mobility in such systems. However, determining the degree of CT character in excimers as a function of their structure has proven challenging. Herein, we report on a series of cyclophanes in which the interplanar distance between two phenyl-extended viologen (ExV2+) chromophores is varied systematically using a pair of o-, m-, or p-xylylene (o-, m-, or p-Xy) covalent linkers to produce o-ExBox4+ (3.5 A), m-ExBox4+ (5.6 A), and p-ExBox4+ (7.0 A), respectively. The cyclophane structures are characterized using NMR spectroscopy in solution and single-crystal X-ray diffraction in the solid state. Femtosecond transient mid-IR and stimulated Raman spectroscopies show that the CT contribution to the excimer states formed in o-ExBox4+ and m-ExBox4+ depends on the distance between the chromophores within the cyclophanes, while in the weak interaction limit, as represented by p-ExBox4+ (7.0 A), the lowest excited singlet state of ExV2+ exclusively photo-oxidizes the p-Xy spacer to give the p-Xy+•-ExV+• ion pair. Moreover, the vibrational spectra of the excimer state show that it assumes a geometry that is intermediate between that of the locally excited and CT states, approximately reflecting the degree of CT character.

Two-photon excited deep-red and near-infrared emissive organic co-crystals.

Abstract: Two-photon excited near-infrared fluorescence materials have garnered considerable attention because of their superior optical penetration, higher spatial resolution, and lower optical scattering compared with other optical materials. Herein, a convenient and efficient supramolecular approach is used to synthesize a two-photon excited near-infrared emissive co-crystalline material. A naphthalenediimide-based triangular macrocycle and coronene form selectively two co-crystals. The triangle-shaped co-crystal emits deep-red fluorescence, while the quadrangle-shaped co-crystal displays deep-red and near-infrared emission centered on 668 nm, which represents a 162 nm red-shift compared with its precursors. Benefiting from intermolecular charge transfer interactions, the two co-crystals possess higher calculated two-photon absorption cross-sections than those of their individual constituents. Their two-photon absorption bands reach into the NIR-II region of the electromagnetic spectrum. The quadrangle-shaped co-crystal constitutes a unique material that exhibits two-photon absorption and near-infrared emission simultaneously. This co-crystallization strategy holds considerable promise for the future design and synthesis of more advanced optical materials. Two-photon excited near-infrared fluorescence materials have garnered considerable attention because of their superior optical properties compared with other optical materials. Here, the authors use a convenient and efficient supramolecular approach to synthesize a two-photon excited near-infrared emissive co-crystalline material.

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.