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

This general overview focuses on novel N-heterocyclic carbene (NHC) Ru complexes, now at the forefront of research in metathesis chemistry, and on their derived multiple applications in targeted organic, polymeric and natural compound synthesis. This outstanding, large class of ruthenium precatalysts combines high activity and selectivity with increased stability and good tolerance towards organic functionalities, air and moisture. The NHC ancillary ligands allow manipulation of the catalytic performance through adjustment of electronic and steric parameters in the ruthenium coordination sphere, facilitate introduction of chiral motifs, and enable convenient immobilization of homogeneous initiators onto solid supports. A broad spectrum of practical applications is discussed.

N-Heterocyclic Carbenes as Highly Efficient Ancillary Ligands in Homogeneous and Immobilized Metathesis Ruthenium Catalytic Systems

Ruthenium‐Vinylidene Complexes: An Efficient Class of Homogeneous Metathesis Catalysts

Stable Nitroxides with Delocalized Positive Charge

Synthesis of imidazol(in)-2-ylidene ruthenium complexes relevant for metathesis and related catalytic processes is described. As an attractive alternative of importance for practical applications, the in situ generation of new NHC ruthenium precatalysts, starting from the easily accessible imidazolium and imidazolinium salts, ruthenium dimer [RuCl2(p-cymene)]2 and a base, is reported in detail. The new NHC family of ruthenium complexes offers great promise as metathesis precatalysts enjoying a wide application profile in organic and polymer synthesis.

N‐Heterocyclic Carbene Ruthenium Complexes: Synthesis and Catalytic Properties

This account critically surveys the field of side-chain transition metal-containing polymers as prepared by controlled living ring-opening metathesis polymerization (ROMP) of the respective metal-incorporating monomers. Ferrocene- and other metallocene-modified polymers, macromolecules including metal-carbonyl complexes, polymers tethering early or late transition metal complexes, etc. are herein discussed. Recent advances in the design and syntheses reported mainly during the last three years are highlighted, with special emphasis on new trends for superior applications of these hybrid materials.

Ileana Dragutan

Papers

N-Heterocyclic Carbenes as Highly Efficient Ancillary Ligands in Homogeneous and Immobilized Metathesis Ruthenium Catalytic Systems

Ruthenium‐Vinylidene Complexes: An Efficient Class of Homogeneous Metathesis Catalysts

Stable Nitroxides with Delocalized Positive Charge

N‐Heterocyclic Carbene Ruthenium Complexes: Synthesis and Catalytic Properties

Recent Advances in Metathesis-Derived Polymers Containing Transition Metals in the Side Chain