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681.
Kristiana T. Santoso Chen‐Yi Cheung Kiel Hards Gregory M. Cook Bridget L. Stocker Mattie S. M. Timmer 《化学:亚洲杂志》2019,14(8):1278-1285
A series of 2‐ and 7‐substituted phthalazinones was synthesised and their potential as anti‐tubercular drugs assessed via Mycobacterium tuberculosis (mc26230) growth inhibition assays. All phthalazinones tested showed growth inhibitory activity (MIC <100 μm ), and those compounds containing lipophilic and electron‐withdrawing groups generally exhibited better anti‐tubercular activity. Several lead compounds were identified, including 7‐((2‐amino‐6‐(4‐fluorophenyl)pyrimidin‐4‐yl)amino)‐2‐heptylphthalazin‐1(2H)‐one (MIC=1.6 μm ), 4‐tertbutylphthalazin‐2(1H)‐one (MIC=3 μm ), and 7‐nitro‐phthalazin‐1(2H)‐one (MIC=3 μm ). Mode of action studies indicated that selected pyrimidinyl‐phthalazinones may interfere with NADH oxidation, however, the mode of action of the lead compound is independent of this enzyme. MIC=minimum inhibitory concentration. 相似文献
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Chen Yi-Wei Liao Pei-Chun Zhang Yu-Xuan Yeh Shang-Yi Wu Yu-Hsuan Qiu Shuo-Bei Tsai Pei-Ni Xin Zhuo Ting Yen-Yu Chen Hsien-Chi Cheung Siu-Fung Hsu Chen-Yun Lien Wan-Hsing Pan Po-Shen 《Research on Chemical Intermediates》2019,45(1):103-118
Research on Chemical Intermediates - One of the most significant challenges in boron neutron capture therapy (BNCT) is to have an ideal boron delivery agent which can deliver sufficient numbers of... 相似文献
684.
A bounce universe model with a scale-invariant and stable spectrum of primordial density perturbations was constructed using a consistent truncation of the D-brane dynamics from Type IIB string theory. A coupling was introduced between the tachyon field and the adjoint Higgs field on the D3-branes to lock the tachyon at the top of its potential hill and to model the bounce process,which is known as the Coupled Scalar and Tachyon Bounce(CSTB) Universe. The CSTB model has been shown to be ghost free,and it fulfils the null energy condition; in addition, it can also solve the Big Bang cosmic singularity problem. In this paper we conduct an extensive follow-up study of the parameter space of the CSTB model. In particular we are interested in the parameter values that can produce a single bounce to arrive at a radiation-dominated universe. We further establish that the CSTB universe is a viable alternative to inflation, as it can naturally produce a sufficient number of e-foldings in the locked inflation epoch and in the post-bounce expansion to overcome the four fundamental limitations of the Big Bang cosmology, which are flatness, horizon,homogeneity and singularity, resulting in a universe of the current size. 相似文献
685.
Timothy Bo Yuan Chen Ivan Miguel De Cachinho Cordeiro Anthony Chun Yin Yuen Wei Yang Qing Nian Chan Jin Zhang Sherman C. P. Cheung Guan Heng Yeoh 《Molecules (Basel, Switzerland)》2022,27(1)
Building polymers implemented into building panels and exterior façades have been determined as the major contributor to severe fire incidents, including the 2017 Grenfell Tower fire incident. To gain a deeper understanding of the pyrolysis process of these polymer composites, this work proposes a multi-scale modelling framework comprising of applying the kinetics parameters and detailed pyrolysis gas volatiles (parent combustion fuel and key precursor species) extracted from Molecular Dynamics models to a macro-scale Computational Fluid Dynamics fire model. The modelling framework was tested for pure and flame-retardant polyethylene systems. Based on the modelling results, the chemical distribution of the fully decomposed chemical compounds was realised for the selected polymers. Subsequently, the identified gas volatiles from solid to gas phases were applied as the parent fuel in the detailed chemical kinetics combustion model for enhanced predictions of toxic gas, charring, and smoke particulate predictions. The results demonstrate the potential application of the developed model in the simulation of different polymer materials without substantial prior knowledge of the thermal degradation properties from costly experiments. 相似文献
686.
Computational Insight into Nickel‐Catalyzed Carbon–Carbon versus Carbon–Boron Coupling Reactions of Primary,Secondary, and Tertiary Alkyl Bromides 下载免费PDF全文
Dr. Man Sing Cheung Fu Kit Sheong Prof. Dr. Todd B. Marder Prof. Dr. Zhenyang Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7480-7488
The nickel‐catalyzed alkyl–alkyl cross‐coupling (C?C bond formation) and borylation (C?B bond formation) of unactivated alkyl halides reported in the literature show completely opposite reactivity orders in the reactions of primary, secondary, and tertiary alkyl bromides. The proposed NiI/NiIII catalytic cycles for these two types of bond‐formation reactions were studied computationally by means of DFT calculations at the B3LYP level. These calculations indicate that the rate‐determining step for alkyl–alkyl cross‐coupling is the reductive elimination step, whereas for borylation the rate is determined mainly by the atom‐transfer step. In borylation reactions, the boryl ligand involved has an empty p orbital, which strongly facilitates the reductive elimination step. The inability of unactivated tertiary alkyl halides to undergo alkyl–alkyl cross‐coupling is mainly due to the moderately high reductive elimination barrier. 相似文献
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Synthesis,Structure, and Reactivity of Anionic sp2–sp3 Diboron Compounds: Readily Accessible Boryl Nucleophiles 下载免费PDF全文
Sabrina Pietsch Dr. Emily C. Neeve Dr. David C. Apperley Dr. Rüdiger Bertermann Dr. Fanyang Mo Di Qiu Dr. Man Sing Cheung Dr. Li Dang Prof. Dr. Jianbo Wang Prof. Dr. Udo Radius Prof. Dr. Zhenyang Lin Dr. Christian Kleeberg Prof. Dr. Todd B. Marder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7082-7098
Lewis base adducts of tetra‐alkoxy diboron compounds, in particular bis(pinacolato)diboron (B2pin2), have been proposed as the active source of nucleophilic boryl species in metal‐free borylation reactions. We report the isolation and detailed structural characterization (by solid‐state and solution NMR spectroscopy and X‐ray crystallography) of a series of anionic adducts of B2pin2 with hard Lewis bases, such as alkoxides and fluoride. The study was extended to alternative Lewis bases, such as acetate, and other diboron reagents. The B(sp2)–B(sp3) adducts exhibit two distinct boron environments in the solid‐state and solution NMR spectra, except for [(4‐tBuC6H4O)B2pin2]?, which shows rapid site exchange in solution. DFT calculations were performed to analyze the stability of the adducts with respect to dissociation. Stoichiometric reaction of the isolated adducts with two representative series of organic electrophiles—namely, aryl halides and diazonium salts—demonstrate the relative reactivities of the anionic diboron compounds as nucleophilic boryl anion sources. 相似文献