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941.
Herman F.M. Schoo Rob C.J.E. Demandt Jeroen J.M. Vleggaar Coen T.H. Liedenbaum 《Macromolecular Symposia》1998,125(1):165-170
The syntheses of partially conjugated alkoxy substituted Poly(p-phenylenevinylene) (PPV) materials with tertiary amines and cationic species covalently bound to the polymer backbone are described. The amine/cationic species are introduced via a polymer analogous reaction of a functional alcohol and the chloro-precursor polymer. Single layer, polymer light emitting diodes (PolyLEDs), prepared with the modified polymer materials show a strong ‘burn-in’ effect, leading to very high electroluminescence (EL) quantum efficiencies especially with higher workfunction cathodes. 相似文献
942.
Numerical Algorithms - Motivated by the high accuracy requirements and the huge ratio of the largest to smallest time scales of Coulomb collision simulations of a considerable number of charges, we... 相似文献
943.
Dr. Ludovic Castro Dr. Yat-Ming So Chang-woo Cho Prof. Dr. Rolf Lortz Kai-Hong Wong Dr. Kai Wang Prof. Dr. Polly L. Arnold Dr. Ka-Chun Au-Yeung Dr. Herman H.-Y. Sung Prof. Dr. Ian D. Williams Prof. Dr. Wa-Hung Leung Prof. Dr. Laurent Maron 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(46):10834-10839
A combined experimental and theoretical investigation on the cerium(IV) oxo complex [(LOEt)2Ce(=O)(H2O)] ⋅ MeC(O)NH2 ( 1 ; LOEt−=[Co(η5-C5H5){P(O)(OEt)2}3]−) demonstrates that the intermediate spin-state nature of the ground state of the cerium complex is responsible for the versatility of its reactivity towards small molecules such as CO, CO2, SO2, and NO. CASSCF calculations together with magnetic susceptibility measurements indicate that the ground state of the cerium complex is of multiconfigurational character and comprised of 74 % of CeIV and 26 % of CeIII. The latter is found to be responsible for its reductive addition behavior towards CO, SO2, and NO. This is the first report to date on the influence of the multiconfigurational ground state on the reactivity of a metal–oxo complex. 相似文献
944.
Dr. Mattia Moiola Dr. Antonio Bova Dr. Stefano Crespi Dr. Misal G. Memeo Prof. Mariella Mella Prof. Herman S. Overkleeft Dr. Bogdan I. Florea Prof. Paolo Quadrelli 《ChemistryOpen》2019,8(6):770-780
Anthracenenitrile oxide undergoes 1,3-dipolar cycloaddition reaction with propargyl bromide affording the expected isoxazole as single regioisomer, suitably synthetically elaborated and functionalized with a protected triple bond. The introduction of a bromine atom at the position C10 of the anthracene moiety allows for inserting a variety of aromatic and heterocyclic substituents through Suzuki coupling. A two-way synthetic route can lead to simple isoxazole derivatives or, after N−O bond reductive cleavage and BF3 complexation, enamino ketone boron complexes. The photophysical properties of both the substituted isoxazoles and the corresponding boron complexes were investigated to show the potentialities for the employment as fluorescent tags in imaging techniques. The quite good quantum yield values confirm the suitability of these compounds in the cellular environment. Scope and limitations of the methodology are discussed. 相似文献
945.
Yongzhen Zhang Marcos Gómez-Redondo Dr. Gonzalo Jiménez-Osés Dr. Ana Arda Prof. Dr. Herman S. Overkleeft Prof. Dr. Gijsbert A. van der Marel Prof. Dr. Jesús Jiménez-Barbero Dr. Jeroen D. C. Codée 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12846-12850
Galactosaminogalactan (GAG) is a prominent cell wall component of the opportunistic fungal pathogen Aspergillus fumigatus. GAG is a heteropolysaccharide composed of α-1,4-linked galactose, galactosamine and N-acetylgalactosamine residues. To enable biochemical studies, a library of GAG-fragments was constructed featuring specimens containing α-galactose-, α-galactosamine and α-N-acetyl galactosamine linkages. Key features of the synthetic strategy include the use of di-tert-butylsilylidene directed α-galactosylation methodology and regioselective benzoylation reactions using benzoyl-hydroxybenzotriazole (Bz-OBt). Structural analysis of the Gal, GalN and GalNAc oligomers by a combination of NMR and MD approaches revealed that the oligomers adopt an elongated, almost straight, structure, stabilized by inter-residue H-bonds, one of which is a non-conventional C−H⋅⋅⋅O hydrogen bond between H5 of the residue (i+1) and O3 of the residue (i). The structures position the C-2 substituents almost perpendicular to the oligosaccharide main chain axis, pointing to the bulk solvent and available for interactions with antibodies or other binding partners. 相似文献
946.
Dr. Lucia Viglianti Dr. Ni Xie Dr. Herman H. Y. Sung Prof. Alexander A. Voityuk Dr. Nelson L. C. Leung Yujie Tu Dr. Clara Baldoli Prof. Ian D. Williams Dr. Ryan T. K. Kwok Dr. Jacky W. Y. Lam Prof. Emanuela Licandro Prof. Lluís Blancafort Prof. Ben Zhong Tang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8630-8637
We have studied the photophysics of tetrafurylethene, an aggregation-induced emission luminogen with exceptionally short intramolecular O−O distances of 2.80 Å and a significant red-shifted morphochromism (27 nm) when going from the aggregate to the crystal. The short O−O distances, which are substantially smaller than the sum of the van der Waals radii (3.04 Å), are due to the fact that the oxygen atoms act as an electronic bridge connecting the furan rings on opposite ends of the central double bond, giving rise to a circular delocalization of the π-electron density across the rings. In the excited state the O−O distance is further reduced to 2.70 Å; the increased O−O interaction causes a narrowing of the HOMO–LUMO gap, resulting in the red morphochromism of the emission. Our results show the structural origin of the red-shifted emission lies in close O−O contacts, paving the way for understanding the clusteroluminescence of oxygen-rich non-conjugated systems that emit visible light. 相似文献
947.
van Delft P Meeuwenoord NJ Hoogendoorn S Dinkelaar J Overkleeft HS van der Marel GA Filippov DV 《Organic letters》2010,12(23):5486-5489
The conjugation of a ribonucleic acid 16-mer with the cationic amphiphilic peptide penetratin and an anionic hyaluronan tetrasaccharide by means of Cu-free "click" chemistry is reported. The alkyne-functionalized 16-mer was prepared by automated solid-phase synthesis, using a newly developed strained cyclooctyne phosphoramidite in the final coupling. Cycloaddition of the alkyne functionalized RNA to the azide containing biomolecules led to a clean conversion into the corresponding nucleic acid conjugates. 相似文献
948.
Retinol is irreversibly oxidized at 790 mV in water 0.1 M LiClO4 that corresponds to formation of retinal. Effect of surfactant on voltammetric characteristics of retinol oxidation has been evaluated. The calibration graph was linear in the range 29.4–980 µM of retinol with detection limit of 15 µM in presence of 1.1×10?4 M of sodium dodecyl sulfate. Application of surfactant media leads to decrease of detection limit, enlargement of analytical range for retinol determination and permits analyze retinol in water media. Simple, express and reliable voltammetric approach for determination of retinol in real samples using surfactant media have been developed. 相似文献
949.
Walvoort MT Lodder G Overkleeft HS Codée JD van der Marel GA 《The Journal of organic chemistry》2010,75(23):7990-8002
Mannosazide methyl uronate donors equipped with a variety of anomeric leaving groups (β- and α-S-phenyl, β- and α-N-phenyltrifluoroacetimidates, hydroxyl, β-sulfoxide, and (R(s))- and (S(s))-α-sulfoxides) were subjected to activating conditions, and the results were monitored by (1)H NMR. While the S-phenyl and imidate donors all gave a conformational mixture of anomeric α-triflates, the hemiacetal and β- and α-sulfoxides produced an oxosulfonium triflate and β- and α-sulfonium bistriflates, respectively. The β-S-phenyl mannosazide methyl uronate performed best in both activation experiments and glycosylation studies and provided the 1,2-cis mannosidic linkage with excellent selectivity. Consequently, an α-Glc-(1→4)-β-ManN(3)A-SPh disaccharide, constructed by the stereoselective glycosylation of a 6-O-Fmoc-protected glucoside and β-S-phenyl mannosazide methyl uronate, was used as the repetitive donor building block in the synthesis of tri-, penta-, and heptasaccharide fragments corresponding to the Micrococcus luteus teichuronic acid. 相似文献
950.
Seong Yong Oh Fang Yu Yueh Jagdish P. Singh Connie C. Herman Kristine Zeigler 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
Laser-induced breakdown spectroscopy (LIBS) was applied to the analysis of simulant slurry samples used in the vitrification process of liquid radioactive wastes. A spectroscopic analysis was performed by two different detection systems: Czerny-Turner spectrometer coupled with intensified diode array detector (IDAD) and an Echelle spectrometer with intensified charge coupled device (ICCD). For the Czerny-Turner detection system, the normalized intensity method, which is the normalization of the atomic emission intensity by the released whole plasma emission area intensity, was employed to improve the reproducibility of LIBS signals. The Echelle detection system showed a high efficiency in simultaneous multi-element detection and determination of the physical quantities of the simulant. 相似文献