Yan Li

Bio: Yan Li is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Melodinus & Benzimidazole. The author has an hindex of 35, co-authored 202 publications receiving 4527 citations. Previous affiliations of Yan Li include Kunming Institute of Botany & Hebei University.

Tailor-made rylene arrays for high performance n-channel semiconductors.

Abstract: ConspectusRylene dyes, made up of naphthalene units linked in peri-positions, are emerging as promising key building blocks to create π-functional materials. Chemists have found uses for these ribbonlike structures in a wide range of applications of optoelectronic devices. Because their structure combines two sets of six-membered electron-withdrawing dicarboxylic imide rings, rylene diimides exhibit enhanced solubility, excellent chemical and thermal stabilities, high electron affinities, and remarkable electron-transporting properties. Among them, perylene diimide (PDI) and naphthalene diimide (NDI) derivatives are important representatives improving the performance of electron-transporting technologies, relative to their p-channel counterparts.Pioneering works by Mullen and Langhals have inspired chemists to extend the π-conjugation along the peri-positions of rylene diimides, which generally results in impressive bathochromic shifts and a nearly linear increase in the extinction coefficient. In additio...

High Mobility, Air Stable, Organic Single Crystal Transistors of an n-Type Diperylene Bisimide

Abstract: Recently, some impressive progress has been made by functionalization of (hetero-)acenes, thiophenes, and arylenes with electron-defi cient constituents. [ 3–5 ] However, the development of air-stable, high mobility, n-type organic semiconductors for organic electronics is still highly emergent. The mobility of organic semiconductors depends on the effi ciency of charge transport from one molecule to another. Hence, some organic semiconductors with dense molecule packing always give high mobility. [ 6 ] As to the stability of organic compounds, it is believed that the highest occupied molecular orbital (HOMO) of p-type organic semiconductors should be more negative than –5.0 eV, e.g., locating at –5.0 to –6.0 eV, and the lowest unoccupied molecular orbitals (LUMO) of n-type organic semiconductors are best located between –4.0 and –4.5 eV, for anti-oxidation in air. [ 2 , 7 ] We have acknowledged these requirements and believe that perylene bisimides (PBIs) will fi t as candidates because of their reasonable electron acceptor ability, [ 8 ] and have been focusing on the expansion of the chemistry of perylene bisimides (PBIs) by a combination of Ullmann coupling and C–H transformation for some time, and have developed a facile strategy to synthesize fully conjugated, triply linked, diperylene bisimides, [ 8 ] conferring the expanded

Plastic pollution in croplands threatens long-term food security

Abstract: Plastic pollution is a global concern given its prevalence in aquatic and terrestrial ecosystems. Studies have been conducted on the distribution and impact of plastic pollution in marine ecosystems, but little is known on terrestrial ecosystems. Plastic mulch has been widely used to increase crop yields worldwide, yet the impact of plastic residues in cropland soils to soil health and crop production in the long term remained unclear. In this paper, using a global meta-analysis, we found that the use of plastic mulch can indeed increase crop yields on average by 25%-42% in the immediate season due to the increase of soil temperature (+8%) and moisture (+17%). However, the unabated accumulation of film residues in the field negatively impacts its physicochemical properties linked to healthy soil and threatens food production in the long term. It has multiple negative impacts on plant growth including crop yield (at the mean rate of -3% for every additional 100 kg/ha of film residue), plant height (-2%) and root weight (-5%), and soil properties including soil water evaporation capacity (-2%), soil water infiltration rate (-8%), soil organic matter (-0.8%) and soil available phosphorus (-5%) based on meta-regression. Using a nationwide field survey of China, the largest user of plastic mulch worldwide, we found that plastic residue accumulation in cropland soils has reached 550,800 tonnes, with an estimated 6%-10% reduction in cotton yield in some polluted sites based on current level of plastic residue content. Immediate actions should be taken to ensure the recovery of plastic film mulch and limit further increase in film residue loading to maintain the sustainability of these croplands.

Melodinines A-G, Monoterpenoid Indole Alkaloids from Melodinus henryi

Abstract: Nineteen monoterpenoid indole alkaloids including seven new ones, melodinines A−G (1−7), were isolated from Melodinus henryi. The structures of the new compounds were elucidated using spectroscopic methods, and the structure of compound 4 was confirmed by single-crystal X-ray diffraction analysis. The known compounds were identified by comparing their spectroscopic data with those reported in the literature. All of the compounds were evaluated for cytotoxic activity against five human cancer cell lines, and compound 11 exhibited cytotoxicity against HL-60, SMMC-7721, A-549, and SK-BR-3 cells with IC50 values of 2.0, 16.8, 25.9, and 24.7 μM, respectively.

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。

Next-generation organic photovoltaics based on non-fullerene acceptors

Abstract: Over the past three years, a particularly exciting and active area of research within the field of organic photovoltaics has been the use of non-fullerene acceptors (NFAs). Compared with fullerene acceptors, NFAs possess significant advantages including tunability of bandgaps, energy levels, planarity and crystallinity. To date, NFA solar cells have not only achieved impressive power conversion efficiencies of ~13–14%, but have also shown excellent stability compared with traditional fullerene acceptor solar cells. This Review highlights recent progress on single-junction and tandem NFA solar cells and research directions to achieve even higher efficiencies of 15–20% using NFA-based organic photovoltaics are also proposed.

Aromatic Trifluoromethylation with Metal Complexes

Abstract: “All new is well-forgotten old”, the proverb goes. The current “fluorine boom” is news only to a novice in the field: the exceptional importance of fluorinated organic compounds in numerous areas has been known for a long time. The sharpest increase in the number of fluorine-containing pharmaceuticals and agrochemicals is dated back to 30 years ago. Also around that time (1979), the first monograph devoted to industrial applications of organofluorine compounds was published, covering not only fluorine-containing biologically active materials but also refrigerants, propellants, surfactants, textile chemicals, polymers, and dyes. The increasingly broad realization of the key role of organofluorine compounds in numerous areas has recently attracted many new scientists to the field. The development of new methods for the selective introduction of fluorine and fluorinecontaining groups into organic molecules for biologically active and other useful materials has become a hot area. Over 100 reviews, book chapters, and highlights on this subject have appeared in the literature in the past few years. As citing all of these publications in this review article is impossible, we provide references to only the most recent, general, and comprehensive ones. Molecules bearing a trifluoromethyl group constitute one of the most important classes of selectively fluorinated compounds. As early as 1928, Lehmann reported his observations of biological activity of some trifluoromethylated organic derivatives and already in 1959 Yale published a detailed review article entitled “The Trifluoromethyl Group in Medicinal Chemistry”. Since then, numerous books and reviews have appeared in the literature covering various aspects of trifluoromethylated organic and organometallic compounds. Within this family, derivatives bearing the CF3 group on aromatic rings are particularly numerous and important. Some examples of such compounds used as active ingredients of pharmaceuticals and agrochemicals are shown in Scheme 1. Trifluoromethylated building blocks and intermediates are clearly needed to make such molecules. The simplest trifluoromethylated aromatic compound, benzotrifluoride, was originally prepared by Swarts at the end of the 19th century. In his work, Swarts treated benzotrichloride with “two thirds of its weight of antimony fluoride” to obtain a mixture of PhCF2Cl and PhCF3, from which the two were separated and isolated pure by distillation. In the early 1930s, two industrial groups, one from Kinetic Chemicals, Inc. and one from I. G. Farbenindustrie AG patented their discoveries on the successful use of HF instead of SbF3 for the Swarts reaction. These inventions were the starting point for the modern large-scale manufacturing of trifluoromethylated aromatics. Other methods have been developed for conversion of various C1 units on the ring to CF3 with a variety of fluorinating agents. While representing an outstanding discovery and a classic of organic and organofluorine chemistry, the Swarts reaction is nonetheless neither atom-economical nor environmentally benign, as it deals with stoichiometric quantities of hazardous chemicals and generates large amounts of chlorine waste. To convert a CH3 group on the ring to CF3, the methyl is first exhaustively chlorinated to produce 3 equiv of HCl as a