Collection of Czechoslovak Chemical Communications最新文献_第10页

Enantioselective synthesis of a taxol C ring 紫杉醇C环的对映选择性合成

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-23 DOI: 10.1135/CCCC2011039

Cong Ma, Stéphanie Schiltz, Joëlle Prunet

引用次数: 5

Isotope exchange reactions of the hydrogen H-5 of selected pyrimidine derivatives and the preparation of tritium-labeled pyrimidines 选定的嘧啶衍生物H-5氢的同位素交换反应及氚标记嘧啶的制备

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-23 DOI: 10.1135/CCCC2011101

M. Dračínský, P. Jansa, T. Elbert

引用次数: 1

A theoretical study of the nitration of eugenol with the nitronium ion 丁香酚氮离子硝化反应的理论研究

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-20 DOI: 10.1135/CCCC2011156

R. Ugarte, G. Salgado, L. Basáez

{"title":"A theoretical study of the nitration of eugenol with the nitronium ion","authors":"R. Ugarte, G. Salgado, L. Basáez","doi":"10.1135/CCCC2011156","DOIUrl":"https://doi.org/10.1135/CCCC2011156","url":null,"abstract":"The nitration of eugenol was investigated by using density functional theory (DFT) calculations. Potential energy surface and molecular electrostatic potential of eugenol was constructed in order to find, respectively, the minimum energy conformers and the possible sites for electrophilic attack. Stationary points were located and characterized at the B3LYP/6-311++G(2d,2p) level of theory. A strongly bound π-complex was found, in which the distance between the nitrogen atom of the NO2 moiety and the C1 carbon atom of the aromatic ring is 2.15 A in the gas phase and 2.06 A in dichloromethane. The most favorable σ-complex or Wheland intermediate is the result from the interaction between the nitrogen and the C6 ring carbon atom. The transition state that connects both complexes is more resembling the σ-complex. The nitronium ion exothermically reacts with eugenol to give the π-complex without an energy barrier. The next stage of the reaction pathway, π-complex → σ-complex, is endothermic and involves a Gibbs energy of activation of 7.9–8.0 kcal mol–1 (gas phase) and 8.3–8.9 kcal mol–1 (CH2Cl2).","PeriodicalId":10674,"journal":{"name":"Collection of Czechoslovak Chemical Communications","volume":"79 1","pages":"1529-1548"},"PeriodicalIF":0.0,"publicationDate":"2011-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1135/CCCC2011156","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63704663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

6-Alkynylpurines bearing electronacceptor substituents: Preparation, reactivity in cycloaddition reactions and cytostatic activity 含电子受体取代基的6-炔基嘌呤:制备、环加成反应活性和细胞抑制活性

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-16 DOI: 10.1135/CCCC2011176

M. Křováček, H. Dvořáková, I. Votruba, I. Císařová, D. Dvořák

引用次数: 3

Assessment on the effects of the operational conditions on the manufacture of PLA-based composites using an integrated compounding–injection moulding machine 使用集成复合-注射成型机评估操作条件对制造pla基复合材料的影响

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-16 DOI: 10.1135/CCCC2011166

Daniel González, A. R. Campos, A. Cunha, V. Santos, J. Parajó

{"title":"Assessment on the effects of the operational conditions on the manufacture of PLA-based composites using an integrated compounding–injection moulding machine","authors":"Daniel González, A. R. Campos, A. Cunha, V. Santos, J. Parajó","doi":"10.1135/CCCC2011166","DOIUrl":"https://doi.org/10.1135/CCCC2011166","url":null,"abstract":"Cellulose fibres were employed as reinforcement agent for biodegradable composites using polylactic acid (PLA) as a polymer matrix. PLA can be obtained from renewable resources, and it is attracting much interest owing to its favourable physico-mechanical properties and biodegradability. Prior to composite compounding, two commercial PLA from different suppliers were characterized for apparent density, flow index, crystallinity, thermal properties, melt flow rheology and intrinsic viscosity for comparison. In experiments performed with an integrated compounding–injection moulding machine (ICIM), the effects of the processing conditions on the mechanical properties of composites (tensile strength, stiffness and strain at break) were analyzed using a Taguchi experimental design. Other properties of the composites, such as surface morphology and fibre length distribution, were also considered. ICIM technology provided composites with better mechanical properties and lower fibre degradation than the conventional sequential extrusion and injection moulding (SEIM) technology.","PeriodicalId":10674,"journal":{"name":"Collection of Czechoslovak Chemical Communications","volume":"76 1","pages":"1509-1527"},"PeriodicalIF":0.0,"publicationDate":"2011-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1135/CCCC2011166","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63704708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

SYNTHESIS, PHYSICO-CHEMICAL AND BIOLOGICAL PROPERTIES OF DNA AND RNA OLIGONUCLEOTIDES CONTAINING SHORT ALKYLAMINO INTERNUCLEOTIDE BOND 含有短烷基胺核苷酸间键的DNA和RNA寡核苷酸的合成、物理化学和生物学性质

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-07 DOI: 10.1135/CCCC2011090

Milena Sobczak, K. Kubiak, M. Janicka, M. Sierant, B. Mikołajczyk, B. Nawrot

{"title":"SYNTHESIS, PHYSICO-CHEMICAL AND BIOLOGICAL PROPERTIES OF DNA AND RNA OLIGONUCLEOTIDES CONTAINING SHORT ALKYLAMINO INTERNUCLEOTIDE BOND","authors":"Milena Sobczak, K. Kubiak, M. Janicka, M. Sierant, B. Mikołajczyk, B. Nawrot","doi":"10.1135/CCCC2011090","DOIUrl":"https://doi.org/10.1135/CCCC2011090","url":null,"abstract":"The condensation of the 5′- O -DMT-3′-deoxy-3′-aminothymidine with 3′- O -TBDMS-thymidine- 5′-aldehyde, followed by reduction of the resultant imine derivative and removal of tert -butyldimethylsilyl (TBDMS) protecting group, provided a dimer (denoted as T NH T), which is a congener of dithymidine phosphate with the phosphate linkage 3′-O-P(O)(OH)-O-5′ replaced with an amino group (–NH–). After phosphitylation of the 3′-OH group, the dimer T NH T was introduced (by the standard phosphoramidite approach) into a central part of the nonadecathymidylate. This oligomer exhibited lower affinity to the complementary single and double stranded DNA complements as compared to unmodified T 19 oligonucleotide. The cleavage of modified oligomer with the snake venom and calf spleen phosphodiesterases was completely suppressed at the site of modification. RNA oligomers containing the T NH T dimer were used for preparation of siRNA molecules directed towards mRNA of BACE1 (beta-site amyloid precursor protein cleaving enzyme). The presence of the T NH T units at the 3′-ends of the RNA strands of the siRNA molecule (the siRNA itself is an effective gene expression inhibitor for BACE1) preserved the gene silencing activity and improved the stability of the modified siRNA in 10% fetal bovine serum.","PeriodicalId":10674,"journal":{"name":"Collection of Czechoslovak Chemical Communications","volume":"76 1","pages":"1471-1486"},"PeriodicalIF":0.0,"publicationDate":"2011-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1135/CCCC2011090","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63703994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Docking alignment-3D-QSAR of a new class of potent and non-chiral indole-3-carboxamide-based renin inhibitors 一类新的有效的非手性吲哚-3-羧胺基肾素抑制剂的对接对准- 3d - qsar

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-04 DOI: 10.1135/CCCC2011070

Jahan B. Ghasemi, S. Pirhadi

引用次数: 7

Electrochemical impedance spectroscopy study of electron transfer at poly(3,4-ethylenedioxythiophene) containing gold nanoparticles coating 含金纳米粒子聚(3,4-乙烯二氧噻吩)涂层上电子转移的电化学阻抗谱研究

Collection of Czechoslovak Chemical Communications Pub Date : 2011-12-02 DOI: 10.1135/CCCC2011109

Stelian Lupu

{"title":"Electrochemical impedance spectroscopy study of electron transfer at poly(3,4-ethylenedioxythiophene) containing gold nanoparticles coating","authors":"Stelian Lupu","doi":"10.1135/CCCC2011109","DOIUrl":"https://doi.org/10.1135/CCCC2011109","url":null,"abstract":"Electrochemical impedance spectroscopy (EIS) was used for characterization of electron transfer in various redox probes, such as the redox couple ferrocyanide-ferricyanide, ferrocene, ferrocenemethanol, and the poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer containing gold nanoparticles. The PEDOT coating was deposited onto platinum (Pt) and glassy carbon (GC) electrodes by galvanostatic electrochemical polymerization from an aqueous solution containing 10 –2 M EDOT and 10 –1 M LiClO 4 as supporting electrolyte. The PEDOT-Au nanoparticles composite coating was prepared by droplet deposition of Au nanoparticles on top of the Pt/PEDOT and GC/PEDOT modified electrodes. The pure PEDOT and PEDOT-Au nanoparticles composite coatings were investigated using EIS and cyclic voltammetry (CV) in 10 –1 M LiClO 4 solution containing various redox probes. The impedance spectra were recorded at the formal redox potential of the redox probes. The charge transfer resistance ( R ct ), solution resistance ( R s ), exchange current density ( i 0 ), standard rate constant ( k 0 ), and double-layer capacitance ( C dl ) were calculated from the EIS data.","PeriodicalId":10674,"journal":{"name":"Collection of Czechoslovak Chemical Communications","volume":"13 4 1","pages":"1433-1445"},"PeriodicalIF":0.0,"publicationDate":"2011-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1135/CCCC2011109","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63704087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

7-Halogenated 7-deazapurine 2′- C -methylribonucleosides 7-卤代7-脱氮嘌呤2′-C-甲基核糖核苷

Collection of Czechoslovak Chemical Communications Pub Date : 2011-11-30 DOI: 10.1135/CCCC2011124

F. Seela, S. Budow, Kuiying Xu, Xiaohua Peng, H. Eickmeier

引用次数: 2

Autofluorescent fused-pyrimidine nucleosides: Synthesis and evaluation as permeants and inhibitors of human nucleoside transporters 自荧光融合嘧啶核苷:作为人类核苷转运体渗透剂和抑制剂的合成和评价

Collection of Czechoslovak Chemical Communications Pub Date : 2011-11-30 DOI: 10.1135/CCCC2011061

I. Nowak, V. Damaraju, C. Cass, J. Young, M. Robins

引用次数: 2