Chiral Macrocycles as Reagents and Catalysts

Ionophores, whether of natural or synthetic origin, encapsulate their ionic “guests” using noncovalent bonding. This encapsulation process resembles, at least superficially, the bonding of a substrate by an enzyme-active site. The analogy to enzymes can be extended further if the ionophore is provided with functional groups that can react with a suitable guest molecule bound in the cavity of the ionophore. We have embedded in the periphery of a macrocycle a 1,4-dihydropyridine, a mimic of the coenzyme NADH. The macrocycle, in addition to having (weak) ionophoric properties, is chiral. The strategy has led to compounds that react as artificial hydrogenases and which are capable of distinguishing, in a predictable fashion, between the prochiral faces of suitable carbonyl substrates. Ancillary developments from this approach have been many. A remarkably general method for the preparation of a wide variety of macrocycles has been developed which depends on some remarkable chemical idiosyncrasies of the cesium ion. In attempts to exploit the chemical possibilities of these macrocycles, unusual chemistry, possibly relevant to the action of the enzyme, 3-phosphoglyceraldehyde dehydrogenase, has been uncovered. In a similar vein, study of macrocycles has led to variants of the aldol condensation on chiral templates. Finally, catalytic CC bond formation mediated by transition metals is revealed to be an area in which chiral macrocycles can play a useful role by acting as chiral ligands for the transition metal.     

Polymers for the 21st Century

Abstract

In the 21st century, polymers will be even more in demand for our modern societal needs than they are today. From the high volume commodity plastics to the highly sophisticated, highly priced, and specially designed low volume functional specialty polymers, an entire rainbow of needs and application possibilities awaits the polymers of the future. In some cases new and improved manufacturing techniques or improvements in the life cycle of these materials will be needed. In other cases completely new polymer structures and their morphologies will have to be developed.     

Macromolecular Architecture for the 21st Century

Abstract

The success of civilizations and technologies has always depended on the efficient use of the available materials.     

21世纪的高分子化学展望

对于２１世纪高分子科学的展望大致如下：２１世纪的特征是能源、材料和环保与健康（或称绿色）。作为材料领域中极其重要的部分,２１世纪对高分子材料在质量方面都有要求,大致可分二个方面同是通过控制聚合而得均匀高分子,其分子量概念不再是各种长短不齐高分子链的平均分子量;二是绿色高分子与绿色反应,前者主要是指生物高分子,对环境稳定高分子则将进行回收与重复使用;所谓绿色反应指所有高分子与相应单体的合成方法都必须     

DNA microarrays: tools for the 21st Century

Profiling of gene expression patterns with microarray technology is widely used in both basic and applied research. DNA microarrays have also shown great promise in clinical medicine and are paving the way toward effective pharmaceutical drug discovery and individualized drug regimens. With growing utilization of this high-throughput technology, new applications are making headlines on a regular basis. This review aims to outline the pros and cons of this methodology and direct the reader towards available useful resources. Various major array formats such as high-density oligonucleotide arrays and spotted cDNA arrays are examined, and advantages and options for using each format are presented. Factors important for the design and analysis of microarray experiments are also discussed.     

Hungarian Chemistry in the 21st Century

Chemical research in Hungary is attracting broad interest, as can be seen from this collection of highlights, all previously published in internationally esteemed journals.     

Aliphatic Polyethers: Classical Polymers for the 21st Century

Polyethers—polymers with the structural element (R'‐O‐R)_n in their backbone—are an old class of polymers which were already used at the time of the ancient Egyptians. However, still today these materials are highly important with applications in all areas of our life, reaching from the automotive and paper industry to cosmetics and biomedical applications. In this Review, different aliphatic polyethers like poly(epoxide)s, poly(oxetane)s, and poly(tetrahydrofuran) are discussed. Special emphasis is placed on the history, the polymerization techniques (industrially and in academia), the properties, the applications as well as recent developments of these materials.

     

双齿氮配体钯配合物催化的羰化反应研究

研究了双齿氮配体钯（II）配合物催化剂（1-3）在对邻溴碘苯与胺的羰化合成酰胺反应以及炔烃的氧化羰化制备炔酸酯反应中的催化性能,考察了不同条件下催化剂的催化活性并对其反应产物进行了表征.研究结果表明该催化剂在酰胺化合成氮取代邻苯二甲酰亚胺的反应中表现出了较好的催化活性和选择性,分离收率和选择性高达88%和85%;在芳基...     

充满希望的新世纪——21世纪化学学科发展的一些看法

20世纪是科学突飞猛进的时代 ,作为自然科学基础学科之一的化学也经历了使人眼花缭乱的 10 0年。基于化学过程的物质生产更是有了飞跃性的发展 ,从而深刻地影响了我们这个地球村的方方面面。今天的高度物质文明离不开化学 ,即使说“化学创造了美好生活”也并不怎么过分。然而 ,当化学家自豪地回顾这百年辉煌之际 ,社会上出现了对化学品的恐惧 ,国内外选择化学作为自己事业的年轻人越来越少 ;一些其他领域的科学家认为化学科学已经发展得十分成熟了 ;而另一些其他领域的科学家则认为化学正在被肢解 ,化学作为一门独立的学科正在消亡。当然 ,…     

面对21世纪的挑战

面对２１世纪的挑战李远哲在过去的十年内，我曾经在不同的场合以同样的话题，发表个人对人类将来的一些看法与关怀。虽然这十年来，世局的改变非常急速，但是我基本的观点并没有改变，改变的是随着世纪转折点的来临，我们必须更坚决地下定决心，加深“迎接挑战”迫切感。...     

中国和21世纪的国际移民研究

在过去四十年中,中国经济的崛起对中国国际移民输入和输出有着重大的转变性的影响,来华国际移民空间特征日益明显,国际移民相关研究也不断丰富。美国−墨西哥边境危机,美国种族人口变化对美国社会的挑战,国际移民向非传统居住地扩展、分散等热点问题,是21世纪以来国际移民研究主要趋势和前沿领域的代表。“一带一路”背景下中国国际移民发展有着光明的前景,“一带一路”倡议给国际移民领域的中国学者提供了难得的机会。在未来的10—20年内,中国的国际移民学者有机会在国际移民数据收集、分析方法、理论创新以及移民政策制定方面做出重要贡献。     

Rhodium Catalysts for Enantioselective Hydrosilylation—A New Concept in the Development of Asymmetric Catalysts

Following a survey of the asymmetric hydrogenation of prochiral olefins with transition metal/phosphane catalysts, the problem of chirality transfer from the optically active ligands of the catalyst to the substrate is discussed. A new concept for this chirality transfer is introduced; the conformational analysis of model compounds as well as the development of catalysts for enantioselective hydrosilylation demonstrate the usefulness of this concept.