摘要:

AbstractOligopeptides are involved in diverse biological activities, including neurotransmission and antibiotic. Many natural‐occurring peptides and peptide‐ketide hybrids exhibit specific biological activities and chemical reactivities upon binding with certain metal ions, such as divalent metal‐binding antibiotic bacitracin and anticancer Fe/Cu‐bleomycin. There are also numerous synthetic peptides designed to bind metal ions to exhibit wide range of physical properties and chemical and biological activities. In this review we summarize the background and discuss our research on metal binding properties, structures, and chemical reactivities of three metallopeptides, the bacterial antibiotic bacitracin, the Alzheimer's disease‐related β‐amyloid, and the salivary antimicrobial histatin. Despite their different structures and biological functions, the Cu2+complexes of these peptides exhibit significant activities toward catechol oxidation and phenol hydroxylation. However, the mechanisms of the oxidative reactions among these three Cu‐peptides seem to be distinctively different. Our current understanding about the structure‐bioactivity relationship and chemical reactivities as well as implications in drug discovery of these peptides are s

ISSN:0009-4536    

DOI:10.1002/jccs.201000043

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractA novel procedure for solid‐phase organic synthesis of 1, 3‐disubstituted uracils using a cyclization‐cleavage strategy from Wang‐acrylate resin, amines and isocyanates. An acrylate ester resin is reacted in turn with PhSeBr and primary amines in one‐pot to affordN‐substituted α‐phenylseleno‐β‐aminoesters followed by treatment with isocyanates to form α‐phenylseleno‐β‐ureidoester resin. Following oxidation‐elimination with excess of 30% hydrogen peroxide and intramolecular cyclization cleavage of the Wang resin using potassium ethoxide as a base to furnish 1, 3‐disubstituted uracils in good yields (80

ISSN:0009-4536    

DOI:10.1002/jccs.201000044

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractMethoxyl silica gel was prepared readily by the treatment of silica chloride with methanol. By using methoxyl silica gel as a dehydrating agent, carboxylic acids reacted with methanol in the presence of a protonic acid such as 12‐phosphotungstic acid afforded the corresponding methyl esters in excellent yield

ISSN:0009-4536    

DOI:10.1002/jccs.201000045

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractThe adsorption behavior of metal cations on gold nanoparticles was investigated by isothermal titration microcalorimetry (ITC) for the first time, and verified by transmission electron microscopy (TEM), and UV absorption spectroscopy. When transition metal cations were injected into the gold colloids, a binding isotherm with a sigmoidal response was obtained; and when instead of alkaline earth cations, the binding isotherm changed from the overall exothermic to endothermic nature. The binding enthalpy depends on the nature and concentration of added cations. The interactions of metal cations with the surface gold atoms and the COO−group of citrate salt that weakly bound on gold nanoparticles are the driving force for the binding; and the binding process is enthalpically driven. TEM images indicate that the addition of metal cations results in the growth and aggregation of gold nanoparticles. After the metal cations were added to the gold colloids, the intensity of the surface plasmon resonance adsorption band at 523 nm of gold nanoparticles decreased, and a new absorption at around 610 nm appeared. This is attributed to gold nanoclusters induced by the surface binding of the metal cations on gold nanoparticles, which is further confirmed by ITC result

ISSN:0009-4536    

DOI:10.1002/jccs.201000046

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractIn this article, we show a simple way to realize the tangent‐sphere model for constructing physical models of arbitrary fullerenes based on beads commonly used in the ornaments and decorative arts. Using suitably chosen weaving strategy, the beaded model can be made to be a faithful π‐bond representation of the corresponding fullerene. Moreover, the shape of a particular beaded model is usually quite close to the true molecular structure of the corresponding fullerene because there is an interesting analogue between microscopic valence shell electron pair repulsion and macroscopic mechanical hard‐sphere interaction in the trivalent beaded models. Systematic rules for constructing fullerenes without any hole are dis

ISSN:0009-4536    

DOI:10.1002/jccs.201000047

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractTo the best of our knowledge, few reports have been concerned with the effect of temperature on photomediated silver nanostructure growth. In this work, the shape evolution from spherical silver nanoparticles to silver nanoprisms and nanostructures in other shapes under the irradiation of a sodium lamp (λmax= 589 nm, 0.66 W/cm2) at various temperatures (i.e., 15, 40, 60, and 80 °C) were studied by recording the TEM images and time‐course UV‐vis‐NIR spectra of the silver colloids. From TEM and spectra analysis, it was found that the photomediated silver nanoparticle shape conversion process would be faster at a higher temperature, i.e., ca. 2 hours at 80 °C, and slower at a lower temperature, i.e., ca. 17 hours at 15 °C. The silver nanoplates synthesized at a higher temperature had a narrower size distribution and were thicker than those synthesized at a lower temperature. Some decahedral silver nanoparticles, about 10% of the final irradiation products, were observed in the synthesis (with a sodium lamp) at 15 °C. In order to produce a higher yield of decahedral silver nanoparticles, the sodium lamp was replaced with blue LEDs (λmax= 450 nm), which have a wavelength closer to the SPR of decahedral silver NPs (ca. 490 nm). The decahedral silver nanoparticles with a fairly narrow size distribution were obtained by irradiating the spherical nanoparticle colloids with the blue LEDs at 2 °C in the absence of PVP or other large‐molecular‐

ISSN:0009-4536    

DOI:10.1002/jccs.201000048

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractThe synthesis of a novel benziloxime ligand, 4,4′‐dibromobenzilmonoxime (DBBOH) (1) and its complexes [Fe(DBBO)3] (2) and Na[Ni(DBBO)3] (3) are described. The ligand (DBBOH) was prepared in MeOH from the reaction of 4,4′‐dibromobenzil with hydroxylamine hydrochloride in the presence of sodium acetate.Reaction of sodium salt of 4, 4′‐dibromobenzilmonoxime (DBBONa) in MeOH with Fe(NO3)3.9H2O and Ni(NO3)2.6H2O yielded [Fe(DBBO)3](2) as yellow and Na[Ni(DBBO)3] (3) as brown precipitates respectively.The ligand, 4, 4′‐dibromobenzilmonoxime (DBBOH) (1) and its complexes [Fe(DBBO)3](2) and Na[Ni(DBBO)3] (3) were characterized by elemental analysis,1H‐NMR and13C‐NMR, IR, and electronic spectral studies.The analysis of IR,1H‐ and13C‐NMR spectral data of Fe(III) and Ni(II) complexes suggest that 4,4′‐dibromobenzilmonoximate is bonded to iron(III) and nickel(II) ions through the oxygen atom of the carbonyl, and the nitrogen atom of the imine groups. The electronic spectral data of the complexes in CHCl3 are in good agreement with the octahedral coordination of Fe(III) and Ni(II) ions. The ligand field parameters for these complexes, i.e. splitting energy and Racah parameter were calculated to be 21560 cm−1and 707 cm−1for [Fe(DBBO)3] (2), 13440 cm−1and 610 cm−

ISSN:0009-4536    

DOI:10.1002/jccs.201000049

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractThe dissolution properties of 3,4,5‐triamino‐1,2,4‐triazole dinitramide in N‐methyl pyrrolidone (NMP) was measured using a RD496‐2000 Calvet microcalorimeter at four different temperatures under atmospheric pressure. Differential enthalpies (ΔdifH) and molar enthalpies (ΔsolH) were determined for 3,4,5‐triamino‐1,2,4‐triazole dinitramide in NMP. The corresponding kinetic equations that describe the four dissolution processes are\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm d\alpha }}}{{{\rm d}t}} = 1.78 \times 10^{ - 4} \left({1 - {\rm \alpha }} \right)^{1.01} \left({T = 298.15{\rm K}} \right) $\end{document},\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm d\alpha }}}{{{\rm d}t}} = 1.96 \times 10^{ - 4} \left({1 - {\rm \alpha }} \right)^{1.06} \left({T = 303.15{\rm K}} \right) $\end{document},\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm d\alpha }}}{{{\rm d}t}} = 2.15 \times 10^{ - 4} \left({1 - {\rm \alpha }} \right)^{0.96} \left({T = 308.15{\rm K}} \right) $\end{document},\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm d\alpha }}}{{{\rm d}t}} = 2.34 \times 10^{ - 4} \left({1 - {\rm \alpha }} \right)^{1.06} \left({T = 313.15{\rm K}} \right) $\end{document}solution of 3,4,5‐triamino‐1,2,4‐triazole dinitramide in NMP, respectively. The values of activation energyEand pre‐exponential factorAfor the dissolution process are obtained as 14.13 k

ISSN:0009-4536    

DOI:10.1002/jccs.201000050

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractNickel oxalate particles were prepared by mixing aqueous solutions of nickel sulfate and oxalic acid at 25 and 85 °C. Effect of composition of the reacting solutions and pH of the resulting dispersion was evaluated on morphology of the precipitated particles. Besides these parameters, isoelectric point of the nickel oxalate played a major role in the particles build up. On control heating at 340 °C, the nickel oxalate particles converted into nickel oxide particles while preserving their particles' integrity to a maximum extent. Selected batches of the as‐prepared and heat‐treated particles were characterized by various physical me

ISSN:0009-4536    

DOI:10.1002/jccs.201000051

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY

摘要:

AbstractA novel stability‐indicating gradient reverse phase ultra performance liquid chromatographic (RPUPLC) method was developed for the determination of purity of Ropinirole in presence of its impurities and forced degradation products. The method was developed using Waters Aquity BEH 100 mm, 2.1 mm, 1.7 μm C‐8 column with mobile phase containing a gradient mixture of solvent A and B. The eluted compounds were monitored at 250 nm. The run time was within 4.5 min which Ropinirole and its four impurities were well separated. Ropinirole was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Ropinirole was found to degrade significantly in oxidative and base stress conditions and stable in acid, water, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of Ropinirole in pharmaceutical dosage forms and dissolution stu

ISSN:0009-4536    

DOI:10.1002/jccs.201000052

出版商:WILEY‐VCH Verlag    

年代:2010

数据来源: WILEY