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1.
The electron transfer reaction between triplet anthraquinone-2-sulfonate and poly-guanylic acid (5') in CH3CN-H2O (97 : 3) has been investigated by 248 nm (KrF) laser flash photolysis. The transient absorption spectra and kinetics obtained from the interaction of triplet anthraquinone-2-sulfonate and poly[G] demonstrate that the primary ionic radical pair, radical cation of poly[G] and radical anion of anthraquinone-2-sulfonate have been detected simultaneously. The free energy changes in the process of the electron transfer were also calculated. 相似文献
2.
Ping Xu Xinyu Jiang Congshan Zhou Kewen Tang 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):447-453
The inclusion interaction between hydroxypropyl-β-cyclodextrin (HP-β-CD) and hydrophilic 2-chloromandelic acid (CMA) was studied by ultraviolet (UV) absorption spectrophotometer. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. 1H NMR spectrum and Thermo-gravimetric/differential thermal analyzer (TG/DTA) techniques were explored to further characterize the inclusion complex, and molecular modeling was used to investigate the mechanism of inclusion interaction. The results showed that HP-β-CD reacted with R,S-CMA to form inclusion complexes, with 1:1 stoichiometry and inclusion stability constants KR and KS were 24 and 39 L/mol determined from UV data by the method of Benesi-Hildebrand’s. Molecular modeling confirmed experimental observation and indicated that the hydrogen bonding interaction plays an important role in the interactive inclusion between HP-β-CD and CMA. Besides, compared with the HP-β-CD, molecular modeling showed R, S-CMA interact with β-CD through different binding modes, in which Vander Waals is the main intermolecular force between β-CD and R-CMA (or S-CMA) while without obvious hydrogen bonding interaction. 相似文献
3.
近年来发现用干扰素处理过的细胞胞浆提取物和双链RNA、ATP一起培养,可以生成一个低分子量的蛋白合成抑制剂,即5′-三磷酸-三聚2′,5′-腺苷酸(Ⅰ)。由于(Ⅰ)具有天然核酸中不存在的2′,5′-磷酸酯链以及它的抗病毒活性,因此引起不少化学家的兴趣,已有不少文章报导了(Ⅰ)及其类似物的合成,同时也发现不含三磷酸的三聚2′,5′-腺苷酸(Ⅱ)也同样具有活性。为了进一步研究(Ⅰ)的结构与活性关系,本文报导了用胞嘧啶碱基代替腺嘌呤碱基的(Ⅱ)的类似物C_(2′P5′)C_(2′P5′)A(Ⅲ)的合成。 相似文献
4.
Sincegramquantitiesoffullereneswereseparatedfromcarbonsoots,manystudieshavebeentriggeredontheirstructures,propertiesandreactions.Asfullerenescanproduceveryhighquantumyieldsofsingletoxygenwhileexcitedbylight,moreinteresthasbeenfocusedontheexaminationoft… 相似文献
5.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1983,39(6):551-553
Vibration-rotation i.r. spectrum of ν2 of methyl iodide was measured with a resolution of 0.08 cm−1. The spectrum was analyzed by taking account of an xy-type Coriolis interaction between ν2 and ν5 and a Fermi resonance between ν5 and ν3 + ν6. The analysis gave values of spectroscopic parameters which include (ν0)2 1251.193 cm−1, A2-A0 0.02030 cm−1, (DJ)2 2.08 × 10−7 cm−1, (DJK)2 3.2 × 10−6 cm−1 and ζ2,5ay −0.6305. 相似文献
6.
《Tetrahedron letters》1997,38(13):2249-2252
An automated online solid-phase synthesis of Ac-cac ct T1GG TC t1ac ct-Gly-OH1 using standard DNA and appropriately protected PNA building blocks (2–5) is described. This chimera forms stable duplexes with complementary DNA and RNA. 相似文献
7.
The effect of ascorbic acid and its analogue 5,6-O-isopropylidenyl-2,3-O-dimethylascorbic acid (I), which has been synthesized for the purpose and does not contain mobile hydrogen atoms, on the
formation of the products of continuous radiolysis of deaerated ethanol and its aqueous solutions has been studied. The ionization
potentials, the molecular orbital energies, the enthalpies of homolytic dissociation of C-H and O-H bonds, and the enthalpies
of H atom addition to the C=O group of the test compounds have been calculated by ab initio methods. The array of the experimental
and calculated theoretical data suggests that both ascorbic acid in the undissociated form and compound I can oxidize α-hydroxyethyl
radicals, whereas the monoanion of ascorbic acid acts as a reducing agent in the reactions with these transient radicals.
The reduction of α-hydroxyethyl radicals in aqueous solutions by the ascorbic acid monoanion can follow both the hydrogen
transfer and electron transfer mechanisms. 相似文献
8.
The products of reaction of α-hydroxyanthraquinones with boric acid are mixtures of 9,10-, 1,10 -, 1,4- and 1,5-quinoid tautomeric
complexes of boric acid and borate esters differing by the coordination bonds with carbonyl groups existing in the dynamic
equilibrium. The deepening of the reagents color in the presence of boron does not a result only of the complexation, but
in the accompanying shift of the tautomeric equilibria. 相似文献
9.
Justyna Mrozek Katarzyna Guzow Emilia Sikorska Wiesław Wiczk 《Central European Journal of Chemistry》2011,9(6):1046-1055
The influence of peptide sequence and Leu chirality in linear and cyclic peptides containing 3-[2-(9-anthryl)benzoxazol-5-yl]alanine on interaction with β-cyclodextrin were studied using fluorescence and NMR spectroscopy. The analysis of enthalpy-entropy compensation effect (α=1.05±0.02 and TΔS0 0=15.1±0.5 kJ mol?1) indicates that the entropic contribution connected with the solvent reorganization is the major factor governing the peptides-β-cyclodextrin complexation. Moreover, spatial orientation of guest-host molecule depends more than association constant on Leu residue configuration. However, the cyclization of the peptide chain substantially decrease the association constant with β-CD. An analysis of 2D NMR spectra reveals that inclusion complex is formed by penetration of cyclodextrin cavity from wider and narrow rims by anthryl group in the case of Box(Ant)-SPKL or anthryl and Leu residues for Box(Ant)-SPK(D)L analogue. 相似文献
10.
K. N. Gusak V. A. Serzhanina N. G. Kozlov V. V. Gren' 《Chemistry of Heterocyclic Compounds》1994,30(10):1220-1223
The reaction of arylidene-2-naphthylamines with the ethyl ester of (2-quinolyl)--oxopropionic acid results in the synthesis of ethyl esters of 1-(2-quinolyl)-3-arylbenzo[f]quinoline-2-carboxylic acids. All the theoretically possible intermediate reaction products were isolated: the amino esters of 2-quinoline--oxopropionic acid, the hydroxy esters of tetrahydro- and esters of dihydrobenzo[f]quinoline-2-carboxylic acid, as well as the by-products — the ethyl ester of 2-quinolyl--(R-benzylidene)--oxopropionic acid. The IR, UV, and mass spectra of the synthesized compounds are discussed.Institute of Physical Organic Chemistry, Belorussian Academy of Sciences, Minsk 220603. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1406–1410, October, 1994. Original article submitted October 5, 1994. 相似文献
11.
Time-resolved laser flash photolysis and pulse radiolysis have been used to study the chemical activity of podophyllotoxin(PPT) and etoposide(VP-16). The mechanism of photoioniza-tion of etoposide and podophyllotoxin has been confirmed and illustrated. It is demonstrated that VP-16 and PPT in aqueous solution can be photoionized at 248 nm to give hydrated electron and neutral radical resulting from rapid deprotonation of radical cation of VP-16 and PPT. The quantum yield for the photoionization of VP-16 and PPT with single-photo is 0.21 and 0.61, respectively. In addition, they can react with hydrated electron, hydrogen radical and hydroxyl radical. This will give chemists some advice on synthesizing new derivatives of podophyllotoxin in cancer treatment. 相似文献
12.
WANG Nai-Xing LI Ji-Sheng ZHU Dao-BenInstitute of Chemistry Chinese Academy of Sciences Beijing China 《中国化学》1996,14(2):167-170
Ammo acid derivatives react with C60 at 110-120℃to form adduct compounds.The products were isolated by column chromatography and were identified by FD-MS,UV-Vis,FT-IR and 13C NMR spectroscopies. 相似文献
13.
Siegfried Vieth Egon Gründemann Klaus Jähnisch Gabriele Winter Günter Reck 《Monatshefte für Chemie / Chemical Monthly》1991,122(12):1035-1045
Summary Reactions of -chloro--cyano--(5-nitrofur-2-yl)-acrylic acid derivatives with malonic acid derivatives in the presence of collidine yield the allyl anions3a–d. The pyridines4, 8 or9 are formed by cyclization of3 under acidic conditions. The 2-chloropyridine4a reacts with nucleophiles under substitution. The treatment of ethyl dichloropropionate1b with C-H-acidic compounds provided the cyclopropanes11 or12, the configurations of which were determined by13C-NMR spectroscopy. The results of the X-ray structure analysis of8c are discussed.
Furylvinylhalogenide, 12. Mitt.: Reaktionen von -Chlor--(5-nitrofur-2-yl)--cyanacrylsäurederivaten mit Malonsäurederivaten
Zusammenfassung Die Umsetzung von -Chlor--cyan--(5-nitrofur-2-yl)-acrylsäurederivaten mit Malonsäurederivaten in Gegenwart von Collidin führt zu Allylanionen3a–d. Unter sauren Bedingungen cyclisiert3 zu den Pyridinen4, 8 oder9. Das 2-Chlorpyridin4a reagiert mit Nukleophilen unter Substitution. Setzt man den Dichlorpropionsäureester1b mit C-H-aciden Verbindungen in Gegenwart von Collidin um, so werden die Cyclopropane11 bzw.12 gebildet, deren Konfigurationen mit Hilfe der13C-NMR-Spektroskopie bestimmt wurden. Die Ergebnisse der Röntgenkristallstrukturanalyse von8c werden diskutiert.相似文献
14.
ZHANG Shu-dong KONG Xiang-he ZHU Xiang-jun WANG Yan JIANG Su-rong 《高等学校化学研究》2006,22(5):621-625
IntroductionReactions of metal ions with neutral molecules orclusters produce a variety of metal complex ions andother new series of cluster ions including cations andanions.The laser ablation-molecular beam(LA-MB)method has marked its relevance in the st… 相似文献
15.
The excited triplet of C60 or C70 is generated via either direct excitation by laser light or energy transfer from excited states of solvent to C60 and C70. The cation radical of C60 is produced either via hole transfer from cation radical of CCl4 to C60 or via electron transfer from excited triplet of C60 to CCl4. C60 and C70 could be added to trichloromethyl radical to produce adduct radicals with different mechanisms. 相似文献
16.
It has been established that the reaction of 3--chloro-5-steroids with trifluoroperactic acid forms not only the 5a,6-peroxides (3a,d), but also the 5a,6-diols (5a,b,d) and their 6-trifluoroacetates.Institute of Bioorganic Chemistry of the National Academy of Sciences of Belarus, 220141, Minsk, ul. Akad. Kuprevicha, 5/2. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 94–99, January–February, 1999. 相似文献
17.
A. I. Lytkin V. V. Chernikov O. N. Krutova I. A. Skvortsov A. S. Korchagina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(1):1-5
The heat effects of the interaction between a solution of α-aminobutyric acid and solutions of HNO3 and KОН are measured by means of calorimetry in different ranges of рН at 298.15 K and values of ionic strength of 0.25, 0.5, and 0.75 (KNO3). The heat effects of the stepwise dissociation of the amino acid are determined. Standard thermodynamic characteristics (Δr H 0, Δr G 0, and Δr S 0) of the reactions of acid–base interaction in aqueous solutions of α-aminobutyric acid are calculated. The connection between the thermodynamic characteristics of the dissociation of the amino acid and the structure of this compound is considered. 相似文献
18.
B. V. Lichitsky A. N. Komogortsev A. A. Dudinov M. M. Krayushkin 《Russian Chemical Bulletin》2008,57(10):2175-2179
New approach to the synthesis of 4,7-dihydro-5H-thieno[2,3-b]pyridin-6-ones using 2-aminothiophenes unsubstituted at position 3 of the thiophene ring has been developed. Labile 2-aminothiophenes
have been obtained by the in situ decarboxylation of unstable 2-amino-3-thiophenecarboxylic acids. The three-component condensation of 2-aminothiophenes with
aromatic aldehydes and the Meldrum’s acid is the key step of the process. 相似文献
19.
《Journal of Coordination Chemistry》2012,65(14):2455-2464
Two transition metal complexes, [Cu2(bpdc)2H2O]·2H2O (1) and Zn(bpdc)(H2O)2 (2) (H2bpdc?=?2,2′-bipyridine-6,6′-dicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Complex 1 is dinuclear with two five-coordinate cupric ions and 2 is mononuclear with one six-coordinate zinc. Interactions of 1 and 2 with DNA have been investigated using UV–Vis absorption spectra. The cleavage reaction on DNA has been monitored by agarose gel electrophoresis. 相似文献
20.
Oguejiofo T. Ujam Ogochukwu E. Offie Pius O. Ukoha Allen G. Oliver Joshua I. Ume Rhonda L. Stoddard 《Journal of Coordination Chemistry》2016,69(19):2807-2818
The reactivity of the metalloligand [Pt2(μ-S)2(PPh3)4] with the boron-functionalized alkylating agents BrCH2(C6H4)B(OR)2 (R = H or C(CH3)2) was investigated by electrospray ionization mass spectrometry (ESI-MS) in real time using pressurized sample infusion (PSI). The macroscopic reaction of [Pt2(μ-S)2(PPh3)4] with one mole equivalent of alkylating agents BrCH2(C6H4)B{OC(CH3)2}2 and BrCH2(C6H4)B(OH)2 gave the dinuclear monocationic μ-sulfide thiolate complexes [Pt2(μ-S){μ-SCH2(C6H4)B{OC(CH3)2}2}(PPh3)4]+ and [Pt2(μ-S){μ-S+CH2(C6H4)B(OH)(O?)}(PPh3)4]. The products were isolated as the [PF6]? salt and zwitterion, respectively, and fully characterized by ESI-MS, IR, 1H and 31P NMR spectroscopy, and single-crystal X-ray structure determinations. 相似文献