共查询到20条相似文献,搜索用时 15 毫秒
1.
Frassineti C Alderighi L Gans P Sabatini A Vacca A Ghelli S 《Analytical and bioanalytical chemistry》2003,376(7):1041-1052
The pKa values of 6-fluoro-4,8-diazadodecane-1,12-diamine (6-fluorospermine) (1), 6,6-difluoro-4,8-diazadodecane-1,12-diamine (6,6-difluorospermine) (2), 6-fluoro-4-azaoctane-1,8-diamine (6-fluorospermidine) (3) and 6,6-difluoro-4-azaoctane-1,8-diamine (6,6-difluorospermidine) (4) in D2O solution have been determined at 40 °C from 13C NMR chemical shifts data using the new computer program HypNMR2000. The enthalpies of protonation of compounds 1–4 and the parent amines spermine (5) and spermidine (6) have been determined from microcalorimetric titration data. The values of H° were used to derive basicity constants relative to 25 °C. The NMR data have been analysed by two different methods to obtain information on the protonation sequence in the polyamines 1–5. The protonation sequence for spermine is related to its biological activity.Abbreviations PKC Protein kinase C - PS Phosphatidylserine - VB Microsoft Visual BasicPresented at the Spanish-Italian Congress on the Thermodynamics of Metal Complexes, Santiago de Compostela, Spain, June 2–6, 2002 相似文献
2.
Tandura S. N. Shumsky A. N. Litvin E. F. Kozlova L. M. Shuvalova E. V. Sharf V. Z. Kolesnikov S. P. 《Russian Chemical Bulletin》2001,50(6):1014-1022
The assignment of the signals for the H and C atoms of four diastereomers (without their separation) of 2-(1-aminoethyl)bicyclo[2.2.1]heptane (1) and its hydrochloride (2) (the antiviral drug deitiforin) was performed for the first time by two-dimensional 1H and 13C NMR spectroscopy. The effects of the substituent at position 2 of norbornane on the chemical shifts of the -, -, and -carbon atoms of the bicycle were examined using the increments for alkanes. The changes in the chemical shifts of the C(6) and C(7) atoms are substantially larger than those for the other C atoms, which made it possible to identify the exo and endo forms. Each of these forms exists as a mixture of two diastereomers. The effect of the positive charge of the N atom on the -protons, which are closely spaced, but separated by a number of covalent bonds, was considered on going from amine 1 to hydrochloride 2. Based on significant changes in shielding of these H atoms, the configurations of the asymmetric center in the CHMe(NH2) substituent of the diastereomers were established. 相似文献
3.
1H and13C NMR spectra of 7-diethylamino-4-(1,2,3-triazol-1-yl)-2H-1-benzopyran-2-one derivatives have been studied. The location of the substituent in the 1,2,3-triazole ring was determined by the 2D COLOC method. It was established that the H(3) and H(5) protons in the coumarin moiety experience anisotropic influence of the phenyl subsituent at the C(5) atom in the triazole ring.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1330–1332, July, 1994. 相似文献
4.
Afonin A. V. Kuznetsova S. Yu. Ushakov I. A. Petrova O. V. Voronov V. K. Mikhaleva A. I. 《Russian Chemical Bulletin》2001,50(3):551-553
The reactions of 2-, 3-, and 4-(1-vinylpyrrol-2-yl)pyridines with methyl iodide afford the corresponding quaternary salts. Analysis of their 1H and 13C NMR spectra showed that the quaternization of the nitrogen atom considerably enhances the -acceptor effect of the pyridine ring on the pyrrole ring and on the vinyl group. 1-Methyl-2-(1-vinylpyrrol-2-yl)pyridinium iodide contains no weak intramolecular C--H...N hydrogen bond present in the starting compound. 相似文献
5.
E. Karthikeyan S. Perumal S. Selvaraj 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2561-2567
A series of substituted 4,9a-diaryl-9,9a-dihydro-1H-[1,4]thiazino[4,3-a][1,3]benzimidazoles was prepared in good yields from the reaction of bis(aroylmethyl) sulfides with ortho-phenylenediamine in glacial acetic acid under reflux and under microwave irradiation. Microwave irradiation is found to accelerate the reaction, besides giving better yield in the case of the thiazinobenzimidazoles with electron-withdrawing groups in the aryl rings than the thermal reaction. 相似文献
6.
Radiochemical 18F-fluorination yields of several compounds using the secondary labelling precursors 2-[18F]fluoroethyl tosylate ([18F]FETos) and 1-bromo-2-[18F]fluoroethane ([18F]BFE) could be considerably enhanced by the addition of an alkali iodide. The radiochemical yield of [18F]fluoroethyl choline for example could be doubled with [18F]BFE and increased from 13% to ≈80% with [18F]FETos. By addition of alkali iodide to the precursor, the 18F-fluoroethylation yields of established radiopharmaceuticals, especially in the case of automated syntheses, could be significantly increased without major changes of the reaction conditions. 相似文献
7.
E. A. Kaigorodova A. A. Osipova L. D. Konyushkin G. D. Krapivin 《Russian Chemical Bulletin》2004,53(4):853-859
Reactions of 2,5-dimethoxytetrahydrofuran with 3-aminothieno[2,3-b]pyridines afford a number of substituted 3-(1H-pyrrol-1-yl)thieno[2,3-b]pyridines. The possibility of the reaction and the yield of the product are determined by the character of a substituent in position 2 of thieno[2,3-b]pyridine. The Curtius rearrangement of 2-acylazido-3(1H-pyrrol-1-yl)thieno[2,3-b]pyridines yields 4,5-dihydropyrido[3",2":4,5]thieno[2,3-e]pyrrolo[1,2-a]pyrazin-4-ones. The molecular and crystal structures of ethyl 4-methoxymethyl-6-methyl-3-(1H-pyrrol-1-yl)thieno[2,3-b]pyridine-2-carboxylate were determined by X-ray diffraction analysis. 相似文献
8.
Isao Hasegawa 《Journal of Sol-Gel Science and Technology》1994,2(1-3):127-130
29Si NMR peaks due to species with the double four-membered ring siloxane backbone composed of both Si(O–)4/2 and CH3Si(O–)3/2 units, (CH3)
n
Si8O
20 – n
/(8 – n) –
(n=1–3), formed by co-hydrolysis of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions in methanol have been assigned. It has been found that 29Si NMR peaks due to Si(OSi)3(O–) units shift to lower frequencies by replacement of the adjacent Si(O–)4/2 units by CH3Si(O–)3/2 units, in other words, with increasing m value in Si[OSi(O–)3]3 – m
[OSi(CH3) (O–)2]
m
(O–) (m=0–2). Peaks from CH3
Si(OSi)3 units in the species have also appeared as separated due to the kind of neighbor structural units. On the basis of the assignments, positions of CH3Si(O–)3/2 units in the cubic octameric siloxane framework of (CH3)
n
Si8O
20 – n
/(8 – n) –
(n=2, 3), for both of which three isomers are present, have been estimated. 相似文献
9.
Arturo González-Hernández 《Journal of organometallic chemistry》2011,696(21):3436-3439
The reaction between the dihydride of decacarbonyltriosmium [H2Os3(CO)10] and phenyl arsine oxide (PAO) in benzene yields only one product [Os3(O)9(μ-H){μ-PhAs(O)OAsPh}] (1), which is characterized by high resolution mass spectrometry (HRMS), Fast Atomic Bombardment Mass Spectrometry (FAB)+, IR, 1H and 13C NMR, and single crystal X-ray diffraction. The solid state X-ray diffraction study of compound (1) shows that the molecule is polycyclic and has an osmium triangle with a bridging hydride bonded to a PhAs(O)-O-AsPh ligand. 相似文献
10.
O. Yu. Smirnov A. Yu. Tyurin A. M. Churakov Yu. A. Strelenko V. A. Tartakovsky 《Russian Chemical Bulletin》2006,55(1):137-140
Thermolysis of 6-azido-5-nitro-7-R-benzotetrazine 1,3-dioxides (R = H and Br) gave benzotetrazine 1,3-dioxides annulated with
the furoxan ring at the C(5)-C(6) bond. According to the NMR data, these compounds at 297 K are equilibrium mixtures of two
isomers with different positions of the N-oxide oxygen atom in the furoxan ring. Full assignment of signals in the 13C NMR spectra of the compounds obtained was accomplished.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 133–136, January, 2006. 相似文献
11.
Sivaperuman Saravanan Shanmugam Muthusubramanian 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2411-2421
Synthesis and characterization of several diethyl 2-[aryl(4-aryl-1,2,3-selenadiazol-5-yl)methyl]malonates are reported. 相似文献
12.
Ernst Haslinger Elisabeth Öhler Wolfgang Robien 《Monatshefte für Chemie / Chemical Monthly》1982,113(11):1321-1327
Steric influences operating on13C-shifts and31P-13C-coupling constants have been investigated on phosphonates with a rigid framework.
Stereochemische Abhängigkeit von13C-Verschiebungen und31P-13C-Kopplungskonstanten in 3-substituierten Bicyclo[2.2.1]hept-5-en-2-yl- und Bicyclo[2.2.2]oct-5-en-2-yl-phosphonaten
Zusammenfassung Der sterische Einfluß auf13C-Verschiebungen und31P-13C Kopplungskonstanten wurde an Phosphonaten mit starrer Struktur untersucht.相似文献
13.
Dilip Kumar Dey Sankar Prasad Dey Amitabha Datta Georgina M. Rosair 《Journal of organometallic chemistry》2009,694(15):2434-440
Two diorganotin(IV) complexes of the general formula R2Sn[Ph(O)CCH-C(Me)N-C6H4(O)] (R = Ph, 1a; R = Me, 1b) have been synthesized from the corresponding diorganotin(IV) dichlorides and the ligand, 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one (1) in methanol at room temperature in presence of triethylamine. Both compounds have been characterized by elemental analyses, IR and 1H, 13C, 15N, 119Sn NMR spectra. The structures of the free ligand and the complexes have been confirmed by single crystal X-ray diffraction. There are three independent molecules in the crystal structure of the ligand 1 and in all three the O-bound proton is transferred to the imine nitrogen and makes an intramolecular N-H?O hydrogen bond with the carbonyl oxygen. In turn this makes an intermolecular hydrogen bond with the phenolic H atom. The crystal structure of 1 is trigonal and a new polymorph; triclinic and monoclinic forms have already been published. In 1a, the central tin atom adopts distorted trigonal-bipyramidal coordination geometry whereas in dimeric 1b it is distorted octahedral when including the intermolecular Sn-O(phenolic) bond [2.7998(20) Å]. The δ (119Sn) values for the complexes 1a and 1b are −306.6 and −127.9 ppm, respectively, thus indicating penta-coordinated Sn centres in solution. 相似文献
14.
Complexation reactions of bivalent metal ions and ethyl-2,3-dioxobutyrate-2p-bromophenylhydrazone (EDOB-2p-BPH) have been studied potentiometrically in 50% (v/v) ethanol/water medium at different ionic strengths with respect to
NaClO4 and at different temperatures and their stability constants determined. The method of Bjerrum and Calvin as modified by Irving
and Rossotti has been used to determine then andpL values. Smin values which have the same significance as ‘T2’ have also been calculated. The thermodynamic stability constants and standard free energy change (ΔG) have also been calculated.
ΔG values are negative in all cases indicating that the reactions are spontaneous. The ligand field stabilization energy (δH)
has also been calculated for the 3d transition metals. 相似文献
15.
G. Siva Mohan Reddy T. Narasimhaswamy K. Mohana Raju 《International Journal of Polymer Analysis and Characterization》2015,20(1):10-28
In the present study, the synthesis and characterization of a methacrylic-based side chain liquid crystalline monomer and its polymer were investigated with the aid of both 1-D and 2-D nuclear magnetic resonance (NMR) techniques. The mesophase characteristics of the monomer and polymer were determined by hot-stage optical polarized microscopy (HOPM). The nematic and smectic phases were observed for the monomer and polymer. Furthermore, 13C spin-lattice relaxation time measurements were performed on the above systems in order to monitor molecular dynamics. The present study provides an opportunity to carry out a systematic comparison of the evolution of structural as well as dynamical changes of the monomer and the polymer. 相似文献
16.
Molero D Coro J Pérez R Suárez M Martínez-Alvarez R Herrera A Martín N 《Magnetic resonance in chemistry : MRC》2007,45(1):93-98
The 1H and 13C NMR spectroscopic data for alkyl and polyamine-linked bis(2-thioxo-[1,3,5]thiadiazinan-3-yl) carboxylic acids, prepared from alkyl diamines and N4-(benzyl) spermidine have been fully assigned by combination of one- and two-dimensional experiments (DEPT, HMBC, HMQC, COSY). 相似文献
17.
Rosa M Claramunt Dionisia Sanz José Elguero 《Journal of organometallic chemistry》2004,689(2):463-470
The 1H, 13C and 15N NMR spectroscopic properties of six thallium tris-(pyrazol-1-yl)borates, including a tetrakis derivative, were determined. The results in solution were necessary to understand those, more complicated, in the solid state. A collection of 205Tl-15N and 205Tl-13C couplings was measured in the latter state. Among those, a very large coupling constant (between 194 and 282 Hz) has been measured on the carbon at the position 4 of the pyrazole ring in several compounds and particularly for the cyclobutyl derivative [Tl(TpCbu)]. It has been assigned to a direct interaction of the 4-C-H ? Tl type and related to the X-ray structures, when available. 相似文献
18.
H.S. Seleem G.A. El-Inany M. Mousa F.I. Hanafy 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(4):869-874
The electronic absorption spectra of a hydrazone: 2-[2-(4-methylquinolin-2-yl)hydrazono]-1,2-diphenylethanone (BHQ) derived from 2-hydrazino-4-methylquinoline and 1,2-diphenylethan-1,2-dione (benzil) have been studied in various solvents of different polarities. The dependence of the band shift Δύ on the solvent parameters viz. D, Z, ET, DN, AN, α, β and π* was discussed. Also, the effect of pH on the free hydrazone and its Co(II), Ni(II) and Cu(II) complexes was studied spectrophotometrically in 75% (v/v) dioxane–water in order to determine the dissociation and stability constants. The stoichiometry of the formed complexes was determined by three different methods: Job's, mole ratio and slope ratio which indicate the formation of 1:2, M:L complexes for Co(II) and Cu(II) and 1:1, Ni(II):L. Beer's law is valid in the range 0.32–7.04 μg/mL depending on the type of the metal ion. The use of BHQ as an indicator via a spectrophotometric titration of Cu(II) and Ni(II) with EDTA was efficient. 相似文献
19.
Mine Sulak Ak Hasalettin Deligöz 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(1-2):115-123
Four new azocalix[4]arenes {5,11,17,23-tetrakis[(2-hydroxy-5-tert-butylphenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (1), 5,11,17,23-tetrakis[(2-hydroxy-5-nitro phenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (2), 5,11,17,23-tetrakis[(2-amino-5-carboxylphenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (3) and 5,11,17,23-tetrakis[(1-amino-2-hydroxy-4-sulfonicacidnapthylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (4)} have been synthesized from p-tert-butylphenol, p-nitrophenol, p-aminobenzoic acid and 1-amino-2-hydroxy-4-sulphonic acid by diazo coupling reaction with p-aminocalix[4]arene. The resulting ligands (1–4) were treated with three transition metal salts (e.g., CuCl2·2H2O, NiCl2·6H2O or CoCl2·6H2O). Cu(II), Ni(II) and Co(II) complexes of the azocalix[4]arene derivatives were obtained and characterized by UV-vis, IR,
1H-NMR spectroscopic techniques and elemental analysis. All the complexes have a metal:ligand ratio of 2:1. The Cu(II) and
Ni(II) complexes of azocalix[4]arenes are square-planar, while the Co(II) complexes of azocalix[4]arenes are octahedral with
water molecules as axial ligands. The solvent extraction of various transition metal cations from the aqueous phase to the
organic phase was carried out by using azocalix[4]arenes (1–4). It was found that, azocalix[4]arenes 1, 2 and 3 examined selectivity for transition metal cations such as Ag+, Hg+ and Hg2+. In addition, the thermal stability of metal:azocalix[4]arene complexes were also reported.
Dedicated to Prof. Dr. Mustafa Yılmaz on the occasion of his 50th birthday 相似文献
20.
Reactions of 2-(1H-benzimidazol-2-yl)phenol (1) and SnPh3Cl, SnPh2Cl2 and SnCl4 were investigated. One tetracoordinated triphenyltin(IV) compound: triphenyltin-2-(1H-benzimidazol-2-yl)phenolate] (3) and its adducts: [O → Sn] dimethylsulfoxide triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (4), [O → Sn] aqua triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (5) [O → Sn] ethanol triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (6), [N → Sn] pyridine triphenyltin-[2-(1H-benzimidazol-2-yl)phenolate] (7), where 1 acts as a monodentate ligand bound through the phenol oxygen, were obtained. In the pentacoordinated compounds 4-7, the tin atom has tbp geometry. The three phenyl groups are in equatorial positions, whereas the benzimidazole and the Lewis base are in apical positions. Two hexacoordinated tin compounds: diphenyltin-bis[2-(1H-benzimidazol-2-yl-κN)phenolate-κO] (8), dichlorotin-bis[2-(1H-benzimidazol-2-yl-κN)phenolate-κO] (9) bearing two bidentate ligands are reported. The coplanar ligands in 8 and 9 form six membered rings by oxygen and nitrogen coordination. The tin geometry is all-trans octahedral. In 8 the two phenyl groups, and in 9 the two chlorine atoms are perpendicular to the plane of the ligands. Compounds were identified in solution mainly by 1H, 13C and 119Sn NMR and in the solid state by X-ray diffraction analysis. 相似文献