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1.
《Tetrahedron letters》1986,27(31):3599-3602
Nucleoside 5′-0-(1-thiodi-) and triphosphates can be obtained in yields of up to 45% directly from the nucleosides. Their diastereomers can be separated by preparative reversed phase chromatography. 相似文献
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Pankaj Sehgal Tami Mizuki Hidekazu Doe Reinhard Wimmer Kim Lambertsen Larsen Daniel E. Otzen 《Colloid and polymer science》2009,287(11):1243-1252
The interactions of α-cyclodextrin (α-CD) with the nonionic surfactant decanoyl-N-methyl-glucamide (Mega-10) and the zwitterionic surfactant dimethyldodecylammoniopropanesulfonate (DPS) in their mixed system have been studied using interfacial tension, fluorescence, and nuclear magnetic resonance measurements. From the plots of interfacial tension vs. log of total surfactant concentration, we have obtained values of the surface excess of surfactant, the critical micellar concentration (cmc), the standard free energy of micelle formation, and association constant of surfactant/α-CD inclusion complexes (assuming a 1:1 stoichiometry). A comparison of the K a values obtained for the interaction between α-CD and DPS and Mega-10, respectively, shows that DPS interacts stronger with α-CD than Mega-10. The experimental mixed cmc was analyzed by the pseudophase separation model and regular solution theory for the evaluation of ideality or nonideality of the mixed micelle formation. The interaction parameters in the mixed micelle and the micelle composition at different mole fractions of DPS were also computed. The fluorescence anisotropy (r) values of rhodamine B decreases with the increase of α-CD concentrations. 相似文献
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Thedithiolenesanddiiminesandtheirmetalcomplexesareanimportantresearchfieldintheorganicandcoordinationchemistry'-'.Metalcomplexesofadithioleneandadiiminehaveexcellentelectronicfullctionsduetotheintramolecularchargetransferfromaligandtootherligand(LL'C... 相似文献
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M. Yu. Kolobov Yu. Yu. Morzherin V. A. Bakulev V. S. Mokrushin 《Chemistry of Heterocyclic Compounds》1991,27(11):1228-1233
The reaction of unsymmetrical N,N-disubstituted malonamides with benzenesulfonyl azide in the presence of sodium ethoxide gives individual sodium 1,2,3-triazol-5-olates or mixtures of their isomers, from the relative amounts of which the effect of substituents in the amido groups on the cyclization pathways and reactivities of -diazoimidolates was ascertained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1521–1527, November, 1991. 相似文献
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A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer. 相似文献
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A strong interaction between double stranded calf-thymus DNA (ds-DNA) and adrenaline in solution, but no interaction between single stranded calf-thymus DNA (ss-DNA) and adrenaline was observed by the use of UV-visible spectroscopy and voltammetric techniques. It is suggested that the interaction leads to an intercalation of adrenaline molecules into the groove of ds-DNA and the formation of ds-DNA (adrenallne)n complex. The binding site size of the interaction of adrenaline with CT-DNA in nucleotide phosphate [ NP] has been determined as 25. The interaction of different concentration adrenaline with DNA modified GCE shows that the DNA modified GCE can be a good tool to detect lower concentration adrenaline. 相似文献
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The widely used antibiotics tetracyclines have been effectively used for ailing heart attack, ulcer cure and gene therapy. The actual mechanism of their activity has been proposed to link with the complexes with many metal ions.However, the sites at which complex formation takes place are not well established. In the present work, the deprotonation sequence of tetracycline (TC) and oxytetracycline (OTC), and their specific group used to bind europium ion were investigated by examining the character of fluorescence of TC and OTC as well as that of their complexes.It was concluded that the site of complexation is coordinated with the deprotonation sequence changing with the acidity/basicity of the solution. And it was inferred that five hydrogens in TC and OTC could be dissociated. The deprotonation sequence is as follows: C(3) hydroxy, C(10) phenol, C(4) dimethylamine, C(12) hydroxy and C(12a) hydroxy. The corresponding complexation site changed with pH increase in solution as follows: C(2) acylamino and C(3) hydroxy moiety, C(10)-C(11) ketophenol moiety, C(4) dimethylamine and C(3) hydroxy moiety,C(11)-C(12)β-diketone moiety, C(12) hydroxy and C(12a) hydroxy moiety, and C(12) hydroxy and C(1) ketonemoiety respectively. 相似文献
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CHENLi CHENXue-si DENGMing-xiao JINGXia-bin 《高等学校化学研究》2005,21(3):340-344
A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ε-Scaprolactone (CL, B) and glycolide (A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL prepolymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide (A) to PCL pre-polymer(BB). The block copolymers were characterized by ^1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer. 相似文献
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Więckowska Anna Bajda Marek Więckowski Krzysztof Malawska Barbara 《平面色谱法杂志一现代薄层色谱法》2010,23(5):359-364
JPC – Journal of Planar Chromatography – Modern TLC - This paper reports an investigation of physicochemical properties of four series of carbamates of 3-hydroxy and... 相似文献
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A homopolymer of methyl methacrylate (MMA) and its copolymer with styrene at different compositions were synthesized and characterized.
Viscosity measurements of the synthesized homopolymer and the copolymers in toluene solutions were performed at 313 K. Different
equations were used to calculate the intrinsic viscosity, viscometric constants values, and molecular weight of the synthesized
polymers. The values of intrinsic viscosity and viscosity average molecular weight obtained by the two methods (single point
determination and graphical extrapolation) were compared in order to verify the validity of the single point determination
for the polymers. Viscometric properties derived included the specific viscosity (it determines the contribution of the solute
to the viscosity of the solution), the reduced viscosity (that provides a measure of the polymer capacity for increasing the
solution viscosity), and the intrinsic viscosity. 相似文献
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StudyofPreparationandCharacteristicsofPyridoxalated PolyhemoglobinLiangShuguang;TongMingrong;PanJilunandYuYaoting(Institutefo... 相似文献
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The optimum conditions were studied for the formation of magnetite by the air oxidation of Fe(OH)2 suspensions. The cation-deficient magnetite (Fe3-δO4, δ>0) was obtained by the air (200mL/min) oxidation of Fe(OH)2 suspensions for 8- 25 h at 343 -358 K and NaOH/FeSO4=2.0 (mole ratio). The oxygen-deficient magnetite (Fe3+δO4, δ>0) was prepared through CO gas reduction of the cation-deficient magnetite at 563 K and its stableness at various temperatures and atomspheres was surveyed. The activity of decomposing water into hydrogen gas with oxygen-deficient magnetite at 563 K was studied and its relations to the oxygen-deficient degree and reaction temperature were investigated, respectively. The results show that the longer the time for magnetite being reduced by carbon monoxide, the higher the oxygen-deficient degree, and the more active its dedcomposition of water is. After reaction, oxygen (O2-) was taken away from water by oxygen-deficient magnetite, which converted to the cation-deficient magnetit 相似文献
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l-Benzoxepino(3, 4-b)quinolin-l3(6H)-one and its halogen,alkyl, alkoxy derivatives Va'-d' and 1-benzothiepino(3,4-b}-quinolin- 13 ( 6H)-one Vf, and its alkyl derivatives Vg, weresynthesized through cyclization of 2-(substituted phenoxymethyl)-3-quinolinecarboxylic acids Va-d and 2-[ (un)substituted phen-ylthiomethyll-3-quinolinecarboxylic acids IVf-g in the presence ofpolyphosphoric acid.The acids IV were obtained from the corresponding ethyl-esters @ whcih were prepared through refluxing ethyl 2-bromo-methyl-3-quinolinecarboxylate(1) with substituted phenol or (un)substituted thiophenol in the presence of NaOEt.The compound Vg, was allowed to react with NBS, KaBH4, NH2OH-HCl to give compounds VII , VIII, and IX, respectively.The structures of 24 new compounds have been confirmed by elemental analysis, IR and 1H NMR. 相似文献
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Liu Hua XU Hu ZHENG Ling Ling WENG 《中国化学快报》2005,16(11):1434-1436
Bone tumor, as a common disease, is treated by surgical resection, radiotherapy and chemotherapy. Chemotherapy is one of the most important treatment, however, a major problem of chemotherapy is lack of selectivity of cytotoxic drugs. Although many attempts have been made to increase the selectivity of therapeutic drugs for the bone diseases, such as osteoporosis, paget’s, hypercalcemia and bone metastases by conjugating them with targeting carriers1-4, there are still no bone-targeting agent… 相似文献
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The present paper covers electronic structures and spectra of the bases and the base pairs of nucleic acids calculated by using the INDO/S method. For free bases we give the energy levels of ground states and transition energies of low-lying excited states and discuss the band characters. The results indicate that the calculated spectra are in good agreement with experimental values. On the other hand, our calculations for A-T and G-C pairs are very beneficial to understanding hydrogen bond properties of these pairs. 相似文献
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Yi LIU Yu Lin DENG Rong ZHENG Pei Long ZHANG Hui ZHAI Kc Zhong LIU Chang Jin ZHU 《中国化学快报》2006,17(5):599-602
Small molecules with the ability to target predetermined sequences of DNA would be valuable tools in molecular biology and potentially in human medicine1-3. Synthetic polyamides consisting of N-methylpyrrole (Py), N-methylimidazole (Im) have received spec… 相似文献
19.
Xiaoyu Wang Lian Li Hong Ye Ke Yang Yanping Wang Daniel J. Sandman 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1323-1327
Micro‐ and nanosized crystals of 1, 4, 8, 11, 15, 18, 22, 25–octabutoxy–29H, 31H–phthalocyanine (Pc) were successfully fabricated through the reprecipitation approach followed by ultrasonication treatment from acetone solution. Phthalocyanine thin films were prepared by vacuum sublimation, spin‐coating and drop‐cast methods, respectively. Field emission scanning electron microscopy (FESEM), UV/VIS/NIR spectroscopy, polarizing optical microscopy and luminescence spectrometry were applied to study phthalocyanine crystal's surface morphology, electronic absorption, birefringence and light emission properties accordingly. The electronic absorption maximum of Pc nanocrystals shifts to longer wavelength compared to that in acetone solution. Birefringence phenomena exist for Pc crystals with different sizes. Fluorescence is observed for both the Pc in acetone solution and thin film. 相似文献
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Yu. A. Mikheev L. N. Guseva Yu. A. Ershov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(4):715-726
The changes in the UV–Vis absorption spectra of dimethylaminoazobenzene (DAB) in the cellulose triacetate (CTA) matrix during the absorption of gaseous hydrogen chloride and protonation of DAB in weakly and strongly acid solutions of hydrochloric and sulfuric acids were studied. The yellow-orange color of DAB and its analog aminoazobenzene (AAB) was shown to be due to the dimers, whose structure involves phenylaminyl type cations formed due to the promotion of the sp 2 electrons of the azo groups to the Rydberg R 3s orbitals of the azo groups and possessing Vis bands at 400–417 nm. The cations exist immanently as the dimers due to the Rydberg intermonomer bonds; the Vis bands of the dimers shifted toward 500–520 nm under the action of HCl (in CTA) and weakly acid media as a result of the formation of phenyl aminyl type pair cations, whose π* levels are split by Simpson’s mechanism, during the protonation of interrelated monomers. In the concentrated sulfuric acid, the Vis bands at 500–520 nm vanished because of the decomposition of the dimers into diprotonated monomers possessing Vis bands at 400–417 nm. The mechanism of transformations of chromogens responsible for the spectral transformation was given. 相似文献