There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

The fascinating story of olefin (or alkene) metathesis (eq
1) began almost five decades ago, when Anderson and
Merckling reported the first carbon-carbon double-bond
rearrangement reaction in the titanium-catalyzed polymerization of norbornene. Nine years later, Banks and Bailey reported “a new disproportionation reaction . . . in which olefins are converted to homologues of shorter and longer carbon chains...”. In 1967, Calderon and co-workers named this metal-catalyzed redistribution of carbon-carbon double bonds olefin metathesis, from the Greek word “μeτάθeση”, which means change of position. These contributions have since served as the foundation for an amazing research field, and olefin metathesis currently represents a powerful transformation in chemical synthesis, attracting a vast amount of interest both in industry and academia.

https://core.ac.uk/download/pdf/4884240.pdf

Ruthenium-based heterocyclic carbene-coordinated olefin metathesis catalysts.

The Golden Age of Transfer Hydrogenation

Structural insights into new luminescent 2D lanthanide coordination polymers using an N, N′-disubstituted benzimidazole zwitterion. Influence of the ligand

New amino-nitroxide spin labels.

The organic chemistry of ruthenium has been one of the most vigorously growing research areas over the past decades. Considerable effort has been extended towards the design and application of a broad series of ruthenium complexes, which culminated with the development by Ryoji Noyori (2001 Nobel Prize for Chemistry) of chiral ruthenium catalysts for stereoselective hydrogenation reactions [1], and the discovery by Robert H. Grubbs (2005 Nobel Prize for Chemistry) of well-defined ruthenium- benzylidene catalysts for olefin metathesis [2] [...].

https://www.mdpi.com/1420-3049/22/2/255/pdf

Special Issue on Ruthenium Complexes

The present work focuses on recent results obtained in polymerization of dicyclopentadiene (DCPD) to linear polydicyclopentadiene (LPDCPD) using two families of highly active and selective tungsten-based catalytic systems. Polydicyclopentadiene, prepared in excellent yield from endo-DCPD with catalysts consisting of WCl6 or WOCl4 and organosilicon compounds, has been structurally characterized by various spectroscopic techniques as well as by DSC and TGA measurements. Microstructure investigations by IR and 13C NMR indicated a prevailingly cis double bond configuration. The linear polymer had a glass-transition temperature of 53°C and exhibited good thermal and electrical properties. The product displayed an appreciable solubility in various organic solvents. From solutions of the linear polymer, elastic and resistant films having a superior adhesion capacity on many solids (wood, metal, plastic materials) could be produced. Alternatively, the catalytic system derived from tungsten tetraphenylporphyrinate and diisobutylaluminoxane, lead to linear polydicyclopentadiene with a predominantly trans configuration at the carboncarbon double bonds. The latter catalytic system behaved in a “living” fashion and allowed polymers with monomodal and narrow molecular weight distribution to be prepared. Block copolymers from dicyclopentadiene with cyclopentene and cyclooctene have also been synthesized. Data recorded in this research provide information concerning the activity and selectivity of the two types of catalytic systems and enable comparison between the structure and configuration of the active sites, the nature of the initiation and propagation reactions, the reaction mechanism and stereochemistry.

Catalyst Activity and Selectivity in ROMP of Dicyclopentadiene Induced by Some Tungsten Systems

The complex ensemble of competing chemical processes (cyclopropanation, metathesis, dimerisation) involved in the reaction of ethyl diazoacetate with styrene is examined in the presence of a panel of ten ruthenium complexes. Our results, focusing on the catalysts’ activity and selectivity, showcased the new NHC-containing complex 10 and the Fischer carbene 7 as leading to best chemoselectivities for cyclopropanation while the bidentate Schiff-base complexes 3 and 4 provided highest stereoselectivity. The traditionally metathesis-active Grubbs I catalyst ( 5 ) could be manipulated, by working under high dilution, to display moderate activity in cyclopropanation whereas the Grubbs II catalyst ( 6 ) totally promoted metathesis. Data obtained with the above set of Ru complexes strongly support the premise that ligand structure and configuration in the Ru coordination sphere are essential factors in controlling the reaction pathways.

Ileana Dragutan

Papers

Structural insights into new luminescent 2D lanthanide coordination polymers using an N, N′-disubstituted benzimidazole zwitterion. Influence of the ligand

New amino-nitroxide spin labels.

Special Issue on Ruthenium Complexes

Catalyst Activity and Selectivity in ROMP of Dicyclopentadiene Induced by Some Tungsten Systems

Catalytic activity and selectivity of a range of ruthenium complexes tested in the styrene/EDA reaction system