Formation of Azulene-Embedded Nanographene: Naphthalene to Azulene Rearrangement During the Scholl Reaction

Incorporation of a non-hexagonal ring into a nanographene framework can lead to new electronic properties. During the attempted synthesis of naphthalene-bridged double [6]helicene and heptagon-containing nanographene by the Scholl reaction, an unexpected azulene-embedded nanographene and its triflyloxylated product were obtained, as confirmed by X-ray crystallographic analysis and 2D NMR spectroscopy. A 5/7/7/5 ring-fused substructure containing two formal azulene units is formed, but only one of them shows an azulene-like electronic structure. The formation of this unique structure is explained by arenium ion mediated 1,2-phenyl migration and a naphthalene to azulene rearrangement reaction according to an in-silico study. This report represents the first experimental example of the thermodynamically unfavorable naphthalene to azulene rearrangement and may lead to new azulene-based molecular materials.     

Enantioselective Total Synthesis of Pseudopteroxazole and Ileabethoxazole

Enantioselective total syntheses of pseudopteroxazole ( 1 ) and ileabethoxazole ( 2 ) are presented. The two original stereocenters were constructed in excellent enantioselectivity and good diastereoselectivity through Carreira's asymmetric dual catalytic allylation, which shows potential for accessing diastereoisomers at C2 and C3 of 1 and 2 . Cationic cyclizations of 13 and 24 demonstrated an effective pathway for the construction of the opposite configurations at C1 in 1 and 2 . Additionally, an approach for the introduction of methyl at C4 is a feasible solution for structural modifications at C4 in 1 and 2 .     

Reaction for the preparation of unique cyclic polysiloxanes with large size and narrow distribution

Utilizing collective forces between reactant and multiple catalyst molecules has been unprecedented due to the difficulty in realizing high order catalysis. Inspired by the power of collective forces in enzymes and organic catalysts, herein we report a rare example of high order catalysis for ring opening reaction (ROR) of strained rings by methanol. ROR is an important way to produce various polysiloxanes, but usually suffers from serious side reactions especially at high conversion, and currently there is a need to design new reaction pathway to achieve low molecular dispersity. In our study, the judiciously designed strained spiral cyclosiloxanes enable a high order catalysis by methanol, and this new methodology leads to a cyclic polysiloxane with high molecular weight and low dispersity even at full conversion of reactants. Kinetic study indicates an extremely unusual high-order reaction involving multiple methanol molecules per reaction, also confirmed by quantum calculation which reveals the presence of zwitterionic ions stabilized by collecting force of hydrogen bonds by methanol molecules. The inherent driving force for this unusual phenomenon is dominated by enthalpy stabilization of the reactive intermediates through hydrogen bonding. The selective formation of Si O Si bonds, instead of silanol products, reflects the power of scientific design.     

Studies of proteasome inhibition and apoptosis induction in triple‐negative breast cancer cells by novel amino acid–polypyridine–copper complex

An innovative ternary copper(II) complex, [Cu(Cl‐PIP)(Tyr)Cl]_n, has been synthesized and characterized using infrared spectroscopy, elemental analysis and single‐crystal X‐ray diffraction analysis. X‐ray crystallography indicates that the Cu atom is five‐coordinated in a square‐pyramidal configuration. The unit forms a one‐dimensional chain along the crystallographic c‐axis. The complex was screened for cytotoxicity against a panel of eight human cancer cell lines, namely MDA‐MB‐231, CAL‐51, K562, HeLa, SGC‐7901, A549, MCF‐7 and SMMC‐7721. The best anticancer activity was obtained with triple‐negative breast cancer CAL‐51 and MDA‐MB‐231 cell lines, with IC₅₀ values in the range 0.035–0.10 μM, and this was better than using carboplatin. The complex inhibits proteasomal chymotrypsin‐like activity, and docking studies reveal its interaction with 20S proteasome. In addition, the complex causes accumulation of ubiquitinated proteins, induces apoptosis and inhibits cell proliferation, indicating its great potential as a novel therapy for triple‐negative breast cancer.     

Formation of Azulene‐Embedded Nanographene: Naphthalene to Azulene Rearrangement During the Scholl Reaction

Incorporation of a non‐hexagonal ring into a nanographene framework can lead to new electronic properties. During the attempted synthesis of naphthalene‐bridged double [6]helicene and heptagon‐containing nanographene by the Scholl reaction, an unexpected azulene‐embedded nanographene and its triflyloxylated product were obtained, as confirmed by X‐ray crystallographic analysis and 2D NMR spectroscopy. A 5/7/7/5 ring‐fused substructure containing two formal azulene units is formed, but only one of them shows an azulene‐like electronic structure. The formation of this unique structure is explained by arenium ion mediated 1,2‐phenyl migration and a naphthalene to azulene rearrangement reaction according to an in‐silico study. This report represents the first experimental example of the thermodynamically unfavorable naphthalene to azulene rearrangement and may lead to new azulene‐based molecular materials.     

Simulation of a Helicon plasma source using a multivariable fuzzymodel

This paper reports work on the development of an automatic control system for a Helicon plasma processing source. The lack of a definitive physical model for the plasma physics of the source and the power coupling mechanism to the plasma precludes the use of traditional control algorithms. This paper develops a fuzzy model that simulates the behavior of the plasma source using the process of genetic algorithms to identify and optimize the parameters of the fuzzy model. This type of model will eventually be used to test a fuzzy control system for the plasma source. In this work, an extensive set of experimental data was acquired where the magnetic field and input power to the plasma source were varied over a wide range while the electron number density was measured. From this learning dataset, the genetic algorithm derived the values of the parameters for the difference equation that describes the system. The fuzzy model so constructed was used to predict the behavior of the source from known input parameters. Comparing the predictions with experimental observations showed that the fuzzy model was generally able to predict the behavior of the plasma as its input parameters were varied with a precision of better than 10%     

Two Typical Examples of Scaling Ionic Partition Scheme for Estimating Correlation Energy of A2 Type Molecules

Based on the calculation results of pair correlation energy contributions of the various electron pairs in Na2 and H2NNH2 systems and the application of the scaling ionic partition scheme for symmetrical A2 type systems, the total correlation energies of Na2 and H2NNH2 have been reproduced by using this simple scheme. The two results show that the absolute deviations are within an acceptable range of error, however, in this way, more than 90% of computational work can be saved. The most attractive result in present paper is that, in these two molecules the coefficients c1 and c2 in the estimation equation can be obtained by the proportion of correlation energy of A^- to that of A^ singlet system. Therefore, it is believed that the proposed ionic partition scheme for symmetrical A2 molecules would be very useful to estimate the correlation energies of large symmetrical molecules.     

A stochastic Ramsey theorem

We establish a stochastic extension of Ramsey's theorem. Any Markov chain generates a filtration relative to which one may define a notion of stopping times. A stochastic colouring is any k-valued (k<∞) colour function defined on all pairs consisting of a bounded stopping time and a finite partial history of the chain truncated before this stopping time. For any bounded stopping time θ and any infinite history ω of the Markov chain, let ω|θ denote the finite partial history up to and including the time θ(ω). Given k=2, for every ?>0, we prove that there is an increasing sequence θ₁<θ₂<? of bounded stopping times having the property that, with probability greater than 1−?, the history ω is such that the values assigned to all pairs (ω|θi,θj), with i<j, are the same. Just as with the classical Ramsey theorem, we also obtain an analogous finitary stochastic Ramsey theorem. Furthermore, with appropriate finiteness assumptions, the time one must wait for the last stopping time (in the finitary case) is uniformly bounded, independently of the probability transitions. We generalise the results to any finite number k of colours.     

193 nm深紫外光刻胶用成膜树脂的研究进展

本文综述了用于193 nm深紫外光刻胶的主体成膜树脂的种类及常用合成单体的研究进展,包括聚(甲基)丙烯酸酯体系、环烯烃-马来酸酐共聚物(COMA)体系、乙烯醚-马来酸酐共聚物(VEMA)体系、降冰片烯加成聚合物体系、环化聚合物体系、有机-无机杂化树脂体系以及光致产酸剂(PAG)接枝聚合物主链型等,并分析了目前关于曝光、分辨率和抗蚀刻性能方面存在的问题及未来的发展方向。