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。

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

A fundamental aim in the field of catalysis is the development of new modes of small molecule activation. One approach toward the catalytic activation of organic molecules that has received much attention recently is visible light photoredox catalysis. In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron-transfer (SET) processes with organic substrates upon photoexcitation with visible light.

Many of the most commonly employed visible light photocatalysts are polypyridyl complexes of ruthenium and iridium, and are typified by the complex tris(2,2′-bipyridine) ruthenium(II), or Ru(bpy)32+ (Figure 1). These complexes absorb light in the visible region of the electromagnetic spectrum to give stable, long-lived photoexcited states.1,2 The lifetime of the excited species is sufficiently long (1100 ns for Ru(bpy)32+) that it may engage in bimolecular electron-transfer reactions in competition with deactivation pathways.3 Although these species are poor single-electron oxidants and reductants in the ground state, excitation of an electron affords excited states that are very potent single-electron-transfer reagents. Importantly, the conversion of these bench stable, benign catalysts to redox-active species upon irradiation with simple household lightbulbs represents a remarkably chemoselective trigger to induce unique and valuable catalytic processes.






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Figure 1


Ruthenium polypyridyl complexes: versatile visible light photocatalysts.

/pdf/visible-light-photoredox-catalysis-with-transition-metal-5d1oxrsczo.pdf

Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis

The use of visible light sensitization as a means to initiate organic reactions is attractive due to the lack of visible light absorbance by organic compounds, reducing side reactions often associated with photochemical reactions conducted with high energy UV light. This tutorial review provides a historical overview of visible light photoredox catalysis in organic synthesis along with recent examples which underscore its vast potential to initiate organic transformations.

Visible light photoredox catalysis: applications in organic synthesis

/pdf/metal-organic-frameworks-and-self-assembled-supramolecular-2xs948xxr9.pdf

Metal–Organic Frameworks and Self-Assembled Supramolecular Coordination Complexes: Comparing and Contrasting the Design, Synthesis, and Functionality of Metal–Organic Materials

Polyoxometalates represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form structures that can bridge several length scales. The new building block principles that have been discovered are beginning to allow the design of complex clusters with desired properties and structures and several structural types and novel physical properties are examined. In this critical review the synthetic and design approaches to the many polyoxometalate cluster types are presented encompassing all the sub-types of polyoxometalates including, isopolyoxometalates, heteropolyoxometalates, and reduced molybdenum blue systems. As well as the fundamental structure and bonding aspects, the final section is devoted to discussing these clusters in the context of contemporary and emerging interdisciplinary interests from areas as diverse as anti-viral agents, biological ion transport models, and materials science.

Polyoxometalate clusters, nanostructures and materials: From self assembly to designer materials and devices

Recent advances in the design and synthesis of organic synthetic metals have yielded materials that have the highest superconducting transition temperatures ( T c ≈ 13 kelvin) reported for these systems These materials have crystal structures consisting of alternating layers of organic donor molecules and inorganic anions Organic superconductors have various electronic and magnetic properties and crystal structures that are similar to those of the inorganic copper oxide superconductors (which have high T c values); these similarities include highly anisotropic conductivities, critical fields, and short coherence lengths The largest number of organic superconductors, including those with the highest T c values, are charge-transfer salts derived from the electron donor molecule BEDT-TTF or ET [bis(ethylenedithio)-tetrathiafulvalene] The synthesis and crystal structures of these salts are discussed; their electrical, magnetic, and band electronic structure properties and their many similarities to the copper oxide superconductors are treated as well

Organic superconductors--new benchmarks.

The formation of CO2 clathrate hydrate was investigated by using time-of-flight neutron powder diffraction at temperatures ranging from 230 to 290 K with a CO2 gas pressure of 900 psi. CO2 clathrate hydrate was prepared in situ from deuterated ice crystals at 230, 243, 253, and 263 K by pressurizing the system with CO2 gas to produce the hydrate in approximately 70% yield. Nearly complete conversion from the hexagonal ice to the sI type CO2 hydrate was observed as the temperature of the sample was slowly increased through the melting point of D2O ice. The conversion of ice into hydrate is believed to be a two-stage process in which an initial fast conversion rate is followed by a slower, diffusion-limited rate. On the basis of a shrinking core diffusion model, an activation energy of 6.5 kcal/mol was obtained from the temperature dependence of the reaction. Our findings suggest that the formation of the hydrate is through a reaction between CO2 and water molecules in the quasi-liquid layer (QLL). The CO2 ...

Neutron Diffraction Studies of CO2 Clathrate Hydrate: Formation from Deuterated Ice

Rational design of synthetic metal superconductors

This contribution reports on the syntheses, structures and cyclometalation reactions of a series of bis(pentamethylcyclopentadienyl)thorium dialkyl complexes of the type Cp'/sub 2/ThR/sub 2/ (Cp' = eta/sup 5/-C/sub 5/Me/sub 5/). It focuses upon the pathway of C-H ..-->.. C'-H hydrogen atom transfer, hydrogen atom positions in the ground states of Cp'/sub 2/Th(CH/sub 2/CMe/sub 3/)/sub 2/ by single-crystal neutron diffraction, and those structural/electronic factors influencing reaction rate and regioselectivity in both neopentyl and modified neopentyl complexes. While on the surface the present d/sup 0/,f/sup 0/ reaction patterns may appear to exhibit similarities to those of the d/sup 8/ and related systems, it will be seen that there are actually profound mechanistic differences. It will also be seen that Th-C bond enthalpy data are useful in understanding certain of the reaction patterns. 63 references, 7 figures, 7 tables.

C-H Activation Mechanisms and Regioselectivity in the Cyclometalation Reactions of Bis(pentamethylcyclopentadienyl)thorium Dialkyl Complexes

Terminal mono-oxo complexes of the late transition metal elements have long been considered too unstable to synthesize because of repulsion between the oxygen electrons and the mostly filled metal d orbitals. A platinum(IV)-oxo compound flanked by two polytungstate ligands, K7Na9[O=Pt(H2O)L2], L = [PW9O34(9-)], has now been prepared and isolated at room temperature as air-stable brown crystals. X-ray and neutron diffraction at 30 kelvin revealed a very short [1.720(18) angstrom] Pt-O bond and no evidence of a hydrogen atom at the terminal oxygen, ruling out a better precedented Pt-OH complex. Density functional theory and spectroscopic data account for the stability of the Pt(IV)-oxo unit by electron withdrawal into delocalized orbitals of the polytungstates.

https://science.sciencemag.org/content/sci/306/5704/2074.full.pdf

Arthur J. Schultz

Papers

Organic superconductors--new benchmarks.

Neutron Diffraction Studies of CO2 Clathrate Hydrate: Formation from Deuterated Ice

Rational design of synthetic metal superconductors

C-H Activation Mechanisms and Regioselectivity in the Cyclometalation Reactions of Bis(pentamethylcyclopentadienyl)thorium Dialkyl Complexes

A Late-Transition Metal Oxo Complex: K7Na9[O=PtIV(H2O)L2], L = [PW9O34]9-