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Han Vinh Huynh Joanne Hui Hui Ho Tiong Cheng Neo Lip Lin Koh 《Journal of organometallic chemistry》2005,690(16):3854-3860
Reaction of N,N′-dimethylbenzimidazolyl iodide (A) with Pd(OAc)2 in DMSO gives selectively trans-bis(N,N′-dimethylbenzimidazoline-2-ylidene) palladium(II) diiodide (trans-2) in 77% yield. The selective formation of the trans-coordination isomer and thus the cis-trans rearrangement is driven by the insolubility of trans-2 in DMSO. X-ray single-crystal diffraction analysis and 13C NMR spectroscopy confirm the trans-geometry of the square planar Pd(II) complex. Catalytic studies show that cis-1 and trans-2 are highly efficient in the Mizoroki-Heck coupling reaction of aryl bromides and activated aryl chlorides both in DMF and [N(n-C4H9)4]Br as ionic liquid. The catalytic activities of Pd(II) complexes with N-heterocyclic carbene ligands derived from benzimidazole are comparable to their imidazole-derived analogues. 相似文献
23.
Sie Tiong Ha Kok Leei Foo Hong Cheu Lin Masato M.Ito Kazuma Abe Kenji Kunbo S.Sreehari Sastry 《中国化学快报》2012,23(7):761-764
正A homologous series of heterocycles,6-methyl-2-(4-alkoxybenzylidenamino)benzothiazoles,were synthesized and characterized using FT-IR,~1H and ~(13)C NMR and mass spectrometric analysis.Enantiotropic nematic phase was observed for shorter members.Smectic A phase only emerged from octyloxy derivative onwards.The terminal methyl group at the benzothiazole fragment and the Schiff base linkage influenced the mesomorphic behavior of the present series. 相似文献
24.
Zhangyong Si Hui Wen Lim Moon Y. F. Tay Yu Du Lin Ruan Haofeng Qiu Rubí Zamudio-Vazquez Sheethal Reghu Yahua Chen Wen Shuo Tiong Kalisvar Marimuthu Partha Pratim De Oon Tek Ng Prof. Yabin Zhu Prof. Yunn-Hwen Gan Prof. Yonggui Robin Chi Prof. Hongwei Duan Prof. Guillermo C. Bazan Prof. E. Peter Greenberg Prof. Mary B. Chan-Park Prof. Kevin Pethe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(17):6886-6893
Carbapenem-resistant Gram-negative bacteria (GNB) are heading the list of pathogens for which antibiotics are the most critically needed. Many antibiotics are either unable to penetrate the outer-membrane or are excluded by efflux mechanisms. Here, we report a cationic block β-peptide (PAS8-b-PDM12) that reverses intrinsic antibiotic resistance in GNB by two distinct mechanisms of action. PAS8-b-PDM12 does not only compromise the integrity of the bacterial outer-membrane, it also deactivates efflux pump systems by dissipating the transmembrane electrochemical potential. As a result, PAS8-b-PDM12 sensitizes carbapenem- and colistin-resistant GNB to multiple antibiotics in vitro and in vivo. The β-peptide allows the perfect alternation of cationic versus hydrophobic side chains, representing a significant improvement over previous antimicrobial α-peptides sensitizing agents. Together, our results indicate that it is technically possible for a single adjuvant to reverse innate antibiotic resistance in all pathogenic GNB of the ESKAPE group, including those resistant to last resort antibiotics. 相似文献
25.
Sie Tiong Ha Kok Leei Foo Ramesh T.Subramaniam Masato M.Ito S.Sreehari Sastry Siew Teng Ong 《中国化学快报》2011,22(10):1191-1194
New Schiff base liquid crystals containing benzoxazole core and alkanoyloxy chain at the end group of the molecules (Cn-1H2n-1COO-,n=14,16,18) was synthesized.The present compounds are enantiotropic smectic A liquid crystals.It was also found that the end groups of the molecules and polar chloro substituent at the benzoxazole fragment had effect on the mesomorphic properties. 相似文献
26.
Sie Tiong Ha Teck Leong Lee Siew Ling Lee Guan Yeow Yeap Yip Foo Win Siew Teng Ong 《中国化学快报》2012,23(2):177-180
A homologous series of azomethine esters,4-n-alkanoyloxybenzylidene-4’-bromoanilines possessing even number of carbon atoms at the terminal alkanoyloxy chain(Cn-1H2n-1COO- n = 8,10,12,14,16,18) was synthesized and characterized.Whilst n-octanoyloxy to n-dodecanoyloxy derivatives exhibited enantiotropic smectic A and smectic B phases,n-tetradecanoyloxy to n-octadecanoyloxy derivatives possessed enantiotropic smectic A and monotropic smectic B properties.n-Decanoyloxy derivatives demonstrated the optimum exhibition for both smectic A and smectic B phases.It was found that the length of terminal alkanoyloxy chain has an influence on mesomorphic properties. 相似文献
27.
This article provides an exploratory case study that examines what one teacher indicated as unexpected as she worked to become more purposeful about her classroom discourse practices. We found that she highlighted three areas as being unexpected: (1) aspects of lesson enactment; (2) characteristics of student learning and (3) her own intentionality or purposefulness. We interpret these instances through the lens of the systemic functional linguistics (SFL) appraisal framework in order to understand how she evaluates the instances she highlights and connect these instances to the literature on values in the teaching and learning of mathematics. 相似文献
28.
A method to prepare α-acyl-β-amino acid and 2,2-diacyl aziridine derivatives efficiently from Cu(OTf)(2) + 1,10-phenanthroline (1,10-phen)-catalyzed amination and aziridination of 2-alkyl substituted 1,3-dicarbonyl compounds with PhI═NTs is described. By taking advantage of the orthogonal modes of reactivity of the substrate through slight modification of the reaction conditions, a divergence in product selectivity was observed. In the presence of 1.2 equiv of the iminoiodane, amination of the allylic C-H bond of the enolic form of the substrate, formed in situ through coordination to the Lewis acidic metal catalyst, was found to selectively occur and give the β-aminated adduct. On the other hand, increasing the amount of the nitrogen source from 1.2 to 2-3 equiv was discovered to result in preferential formal aziridination of the C-C bond of the 2-alkyl substituent of the starting material and formation of the aziridine product. 相似文献
29.
A detailed optical characterization of vertically aligned ZnO microrods (μRs) grown using a Ni-based catalyst was carried out by excitation-power- and temperature-dependent photoluminescence (PL) measurements. Low-temperature PL spectra of ZnO μRs are dominated by near-band-edge (NBE) emission consisted of a series of sharp lines typical for the bulk ZnO. Starting from the higher energy free exciton (FX) emission feature, the majority of them can be explained by radiative recombination of excitons bound to neutral donors (D0X), defect bound exciton (DBX), two-electron satellites emission, free-to-bound, i.e. free electrons to the neutral acceptors (eA0) transition, as well as their longitudinal-optical phonon replicas. An additional excitonic line located in between the FX and D0X lines, denoted as the surface excitons (SX) for ZnO μRs is observed. The intensity of the SX line is found to be smaller than that of the nanosized counterpart and has been attributed to the surface–volume ratio effects. The excitation-power-dependent results of FX line at low and high power regimes show quite close values corresponding to, respectively, p=2 and p=1 limits of the theoretical power law expression I~Lp and larger deviations for the D0X, SX and DBX lines. The temperature-dependent measurements confirmed the presence of eA0 line showing kT/2 influence to the position of eA0 emission line in comparison with FX. FX emissions persist up to 300 K and together with the dominant eA0 emission govern the line shape of the NBE emission range, while D0X and SX lines are quenched completely at 150 K. 相似文献
30.
Feng Yu Vincent Tiing Tiong Le Pang Rusen Zhou Xiaoxiang Wang Eric R. Waclawik Kostya Ken Ostrikov Hongxia Wang 《中国化学快报》2019,30(5):1115-1120
Due to the synergistic effect between ZnS and Cu5Sn2S7, the ZnS can enhance electrochemical performance of pristine Cu5Sn2S7. 相似文献