A Study on Alkyl Polyglycosides of the Starch

The alkyl polyglycosides (APG) is new type the surfactants that is made by regeneration resource of the starch and the grease, since the nineties of 20th century it is energetically exploited in international extent. APG not only good in surface activity,but also plenty on bubble, thin greasy and stabilization, there are good decontamination, compatibility, innocuity, not incitation and unique function that organism decomposition of swiftness and downrightness, and so on. APG is to get produ…     

On the Relative Importance of O–H/π Interactions in 7-Norbornenols

The geometries of the two H–O–C rotamers of synand two of anti-7-norbornenol have been optimized at the ab initio HF/6-31G** and B3LYP hybrid HF-DFT levels of theory by using a 6-31G** basis set. Contrary to an earlier report, we find that the (nongeometry constrained) anti-trans isomer (1d) is predicted to be more stable than the corresponding syn-cis form (1a). The increased stability of 1d vis-à-vis 1a can be accounted for in terms of relative H(1)–C(2)–O(3)–H(4) torsion energy effects. The computational results indicate that the hydroxyl proton in 1a enters into intramolecular hydrogen bonding with the proximate C=C bond. Supporting evidence for this conclusion resides in the fact that the 1a is predicted to possess the lowest O–H stretching frequency, a result that can be attributed to -hydrogen bonding.     

Comparison of the Separation Characteristics of the Organic–Inorganic Hybrid Stationary Phases XBridge C8 and Phenyl and XTerra Phenyl in RP-LC

Differences in the system constants of the solvation parameter model and retention factor correlation plots for varied solutes are used to study the retention mechanism on XBridge C₈, XBridge Phenyl and XTerra Phenyl stationary phases with acetonitrile–water and methanol–water mobile phases containing from 10 to 70% (v/v) organic solvent. These stationary phases are compared with XBridge C₁₈ and XBridge Shield RP₁₈ characterized in an earlier report using the same protocol. The XBridge stationary phases are all quite similar in their retention properties with larger difference in absolute retention explained by differences in cohesion and the phase ratio, mainly, and smaller changes in relative retention (selectivity) by the differences in individual system constants and their variation with mobile phase type and composition. None of the XBridge stationary phases are selectivity equivalent but XBridge C₁₈ and XBridge Shield RP₁₈ have similar separation properties, likewise so do XBridge C₈ and XBridge Phenyl, while the differences between the two groups of two stationary phases is greater than the difference within either group. The limited range of changes in selectivity is demonstrated by the high coefficient of determination (>0.98) for plots of the retention factors for varied compounds on the different XBridge phases with the same mobile phase composition.     

A Theoretical Study on the Equilibrium Structures and Relative Stabilities of H_2SO

1INTRODUCTIONTheconformationandvariousphysicalprope-rtiesofdichalcogencompoundsR-X-Y-R?(X,Y=O,S,Se,andTe)havebeenatopicofseveralexperi-mentalandtheoreticalinvestigations[1].CompoundscontainingS=SandS=Obondshavelongbeenpro-posedasintermediatesinorganicsynthesisand,onoccasion,asstableentities[2～18].Despitethecom-monlyusedrepresentationofS–Obondinsulfoxi-desandothersulfinylderivativesasS=O,sulfoxidesareinmanywaysbestdescribedasylideswithhighlypolarizedS–Oσ-bondbecauseofelectro-sta…     

A DFT Study on the Interactions between Sulfolane and Aromatic Hydrocarbons

The B3LYP method with 6-31G^*, 6-311+G^* and aug-cc-pvdz basis sets was used to predict the geometries of aromatic hydrocarbon (benzene, toluene, benzonitrile) and sulfolane interaction systems. Nine stable conformers were obtained with no imaginary frequencies. The interaction energies of these binary mixtures have been obtained at the B3LYP/6-31G^*, B3LYP/6-311+G^* and B3LYP/aug-cc-pvdz levels. The natural bond orbital (NBO) and the atoms in molecules theory (AIM) were used to analyze the nature of the interactions at these levels. The results show that hydrogen bonds are present in these systems. Of all levels, the interaction of the sulfolane-benzonitrile system at B3LYP/6-311+G^* is the strongest with an interaction energy of −21.84 kJ⋅mol⁻¹ (BSSE corrected), and the intensity order of the interactions is A(2) > A(3) > A(1), B(2) > B(3) > B(1), C(2) > C(3) > C(1), and C(2) > B(2) > A(2).     

A Relative Study on Two-photon Absorption Properties of C60 and C70

We have theoretically investigated the one- and two-photon absorption properties of C60 and C70 using the ZINDO method. From the results it is suggested that the one-photon absorption spectra are in agreement with the experimental observations. It is found that the maximum TPA cross section of C70 is more than twice that of C60,which is consistent with the experimental results. A notable point is that the TPA process of C60 is different from that of C70 as well as other ordinary conjugated molecules.     

LC and LC–MS Study of the Bioavailability and Metabolites of TM208 after Oral and Intravenous Administration to Rat

4-Methylpiperazine-1-carbodithioic acid 3-cyano-3,3-diphenylpropyl ester hydrochloride (TM208) is a new compound expected to become a new drug because of excellent in vivo and in vitro anticancer activity and low toxicity. A new, specific and sensitive LC method was set up for detecting the bioavailability of TM208 after oral administration. Samples were extracted with ethyl acetate after oral and intravenous administration. The retention times of TM208 and plunarizine (I.S.) were 5.5 and 9.9 min, respectively. The linear range was 0.125–50 μg mL^?1. The accuracy (error, %) for three concentrations was 2.7–16.6%. Intra-day precision (as RSD) was 1.6–6.9% and inter-day precision was 7.6–11.5%. Extraction recovery of TM208 was 84.15–89.51% and that of the I.S. was 83.3%. Results from stability testing indicated that samples should be analyzed within 24 h or frozen immediately for later analysis. The bioavailable fraction (F) calculated by use of a non-compartment model was 63.3%. Pharmacokinetic data for TM208 were: mean residence time 24.3 and 5.1 h, V _d 186.2 and 35.5 L kg^?1, and Cl 6.9 and 4.2 L h^?1 kg^?1 after oral and intravenous administration, respectively. LC–MS comparison of the metabolites after the two methods of administration showed the kind and content of metabolites of TM208 in rat urine after intravenous administration were more than after oral administration. The experimental results show that the low anticancer activity of TM208 after intravenous administration is related to rapid elimination of the drug, and that the kind and content of metabolites do not affect the bioactivity of TM208.     

Comparison of LC–UV, LC–ELSD and LC–MS Methods for the Determination of Sesquiterpenoids in Various Species of Artemisia

Simple and specific analytical methods for the quantitative determination of sesquiterpenoids from various species of Artemisia plant samples were developed. By LC–UV, LC–ELSD, the separation was achieved by reversed-phase chromatography on a C18 column with water and acetonitrile both containing 0.025% trifluoroacetic acid as the mobile phase. In the LC–MS system, trifluoroacetic acid was replaced by 0.1% formic acid. The wavelength used for quantification of sesquiterpenoids with a diode array detector was 205 nm. The limits of detection by LC–MS was found to be 5, 10, 25, 50, 50 ng mL^?1. The limits of detection by LC–UV and LC–ELSD were found to be 5.0, 3.0, 100, 100, 7.5 μg mL^?1, by LC–UV and 50, 25, 30, 100 and 75 μg mL^?1 by LC–ELSD. LC–mass spectrometry coupled with electrospray ionization (ESI) interface is described for the identification and quantification of sesquiterpenoids in various plant samples. This method involved the use of the [M + H]⁺ ions of sesquiterpenoids in the positive ion mode with extractive ion monitoring.     

Effect of Chemical Modification of the Tetrapyrrole Macrocycle Structure on the Spectral,Acid–Base,and Complexing Properties of tert-Butyl-Substituted Porphyrazines

Russian Journal of Organic Chemistry - The effect of chemical modification of the tetrapyrrole macrocycle structure on the spectral, acid–base, and complexing properties of...     

UV–Spectral Study on the Effects of Inert Salts on the Nonionic Micellar Solubilization of Phenyl Salicylate in the Absence and Presence of a Cationic Surfactant Under Alkaline Aqueous Medium

The values of the fraction of ionizes phenyl salicylate, f_PS-, obtained from initial absorbance measurement of phenyl salicylate at 350 nm, remain unchanged with the increase in [CH₃CO₂Na] from 0.0 to 0.7 M at 0.01 M NaOH (f_PS- ≈ 0.70) and 0.02 M NaOH (f_PS- ≈ 0.93). The values of f_PS- decrease from ～ 1.0 to 0.90 and ～ 1.0 to 0.84 with the increase in respective [CH₃CO₂Na] and [NaBr] from 0.0 to 0.6 M at 0.01 M NaOH, 0.02 M C₁₂E₂₃(=C₁₂H₂₅(OCH₂CH₂)₂₃OH) and 0.01 M CTABr (=C₁₆H₃₃NMe₃Br).     

LC–MS–MS Analysis of Strictosamide in Rat Plasma, and Application of the Method to a Pharmacokinetic Study

A rapid and simple high-performance liquid chromatographic tandem mass spectrometric method has been developed and validated for analysis of strictosamide in rat plasma. Chromatographic separation was achieved on a C₁₈ column by gradient elution with mixtures of methanol, water, and acetonitrile containing 0.05% acetic acid. Digoxin was used as internal standard. Selected reaction monitoring (SRM) was used for MS quantitation. Linearity was good in the range 0.05–20 ng mL^?1 in rat plasma. The lower limit of quantitation was 0.04 ng mL^?1. The method is precise and reliable and can be applied to pharmacokinetic studies.     

Lewis Acid-Mediated Addition of Lithiated Alkyl Phenyl Sulphones and Oxiranes. A Method for Synthesis of α, β-Unsaturated Ketones

Efficiency of the reaction of lithiated alkyl aryl sulphones (1–4) with oxiranes (5, 6) is increased by the presence of BF₃ or CeCl₃. The respective adducts (7–14) were transformed into α,β-unsaturated ketones (15–22) with high yields.     

Relative Stabilities and Molecular Structures of the Geometrical Isomers of α,α′-Dioxasubstituted Cycloalkylidenecycloalkanes. A DFT Study

The relative stabilities and molecular structures of the geometrical isomers of seven ,-dioxa derivatives of cycloalkylidenecycloalkanes with 3to 6-membered rings have been studied by DFT calculations at the B3LYP/6-31G* level of theory. In each case, the E form was calculated to have the lower total energy. The relative energy of the Z isomer proved to increase regularly with increasing sizes of the two heterocyclic rings, ranging from 1.1 to 13.8 kJ mol^–1 on going from the 3,3to the 6,6-membered rings. Intermediate values of the relative energy were calculated for the Z forms of compounds containing two dissimilar rings. The relative energy of the Z isomer was found to be proportional to d ^–9.3, where d = the distance separating the two O atoms of the Z compound. The molecular structures, electric dipole moments, and atomic charges on the O atoms are also discussed.     

Study on the synthesis,morphology and structural analysis of fly ash–cyclodextrin composite

This study investigates the surface morphology, structure analysis and the effect on the porosity and particle size of a new composite prepared using fly ash with α and β cyclodextrins. The dry mix and solution methods were used to synthesize these composite samples. The X-ray diffraction analysis shows the new peaks that indicate the interaction between the materials. These results are in agreement with the Fourier transform infrared spectroscopic analysis that suggested the possibility of interaction of fly ash particles with cyclodextrin. Morphology changes between the composite material and the constituent materials were observed using the scanning electron microscopic. The porosity and particle size analyses show the significant changes with respect to preparation methods.     

Study on the structure–activity of dihydromyricetin and its new production

Myricetin (MY) was firstly synthesized from dihydromyricetin (DMY), and its antioxidant activity was analyzed. FTIR, NMR, and TG measurements confirmed that the DMY turned to MY. Scanning electron microscope observation showed that the 2,3-single bond offered great flexibility on the stage of crystallization to form imperfect crystalline regions; hence, DMY tends to form larger columnar crystals than MY. It has been found that the antioxidative efficiency of DMY was superior to MY, based on the measurement of radical scavenging activity by DPPH and the oxidation induction time of PP-antioxidant samples. The 2,3-double bond in MY structure, known as one of the characteristic determinants, was not an important requirement for antioxidant capacity or even negative correlation observed. Such a deduction was further supported by UV–Vis absorption spectra change when the pH was raised to pH 9. It was concluded that the ortho-trihydroxyl group in the B ring provides an antioxidant defense, and the 2,3-single band of C ring provides the structural stability.     

A Study on the Simultaneous Determination of Copper and Tin in the Presence of Lead

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Study on the microstructure and liquid–solid correlation of Al–Mg alloys

Based on the available structural models and theories of electrical resistivity (ER) of liquid alloys, the structure and the liquid–solid correlation of Al _(100-x) Mg_x (x = 0, 10, 20, 30, 40, 50) alloys have been qualitatively studied by measuring the ER during the heating/cooling process using the direct-current (DC) four-probe method, as well as by characterizing the solidification morphology and testing the hardness. The result shows that the ER of Al–Mg alloys increases with the increasing temperature and the Mg content; thermal state and history have an effect on the solidification structure and properties: the ER of Al–Mg alloys exhibits a lag phenomenon of structure change during the heating/cooling process. A higher heating/cooling rate contributes to the more obvious relaxation effect of ER and the more uniform structure. Furthermore, higher pouring temperature (PT) leads the melts and solidification structure to be more homogeneous, which increases the hardness.     

Solution Properties of NaHSO4 and Na2SO4: A New Sight from the Water–Ion and Water–Dipole Cooperative Interactions Using Dielectric Relaxation Spectroscopy

The aqueous NaHSO₄ and Na₂SO₄ solutions at concentrations of 0.1–1.0 mol/l in a limited frequency range 0.2–20 GHz are studied by dielectric relaxation spectroscopy with a newly developed fractal concept spectral function. The fractal analysis with α(lnτ) diagrams from dielectric relaxation spectroscopy as functions proposed a new strategy to shed light on the dual nature of ion–water and dipole–water cooperative interactions. A distinct cooperative interaction of ion–water and dipole–water is observed and water molecules perturbed by ions contributing to dielectric constant beyond the first hydration shell is obtained.     

Study on the Epoxidation of a, β-Unsaturated Ketones Catalyzed by MCM-41 Supported Schiff Base

介孔分子筛MCM-41依次与3-氯丙基三乙氧基硅烷、环己二胺和三唑醛反应,得到席夫碱修饰的新型介孔分子筛MCM-41催化剂.通过傅里叶变换红外光谱（FTIR）和X射线多晶衍射（XRD）等方法对所得催化剂进行表征.以过氧化氢为氧源,介孔分子筛MCM-41负载的席夫碱为催化剂,研究了α,β-不饱和酮的环氧化反应,考察了金属盐、溶剂、催化剂用量、反应时间等因素对环氧化反应的影响.结果表明,在室温下乙腈溶剂中,α,β-不饱和酮的环氧化反应在短时间内均以很高的产率（高达99%）得到了相应的产物.同时,对催化剂的重复利用进行了研究,发现重复使用四次,仍能以较高产率得到环氧化产物.     

Study on the Inclusion Interactions of β‐Cyclodextrin and Its Derivative with Clomipramine by Spectroscopy and Its Analytic Application

Abstract

The inclusion interactions of β‐cyclodextrin (β‐CD) and its derivative, namely hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) with clomipramine (CLOM) have been investigated. The guest molecule was clomipramine and inclusion complexes were characterized by UV, ¹H NMR, ¹³C NMR, and 2D NMR spectroscopy. The main factors affecting the inclusion interaction were discussed in detail. The inclusion complexation behaviour of cyclodextrins with clomipramine was studied in an aqueous buffer solution of pH 4 and pH 5 at room temperature. According to the continuous variation method (Job's plot) applied to spectroscopy measurements a 1∶1 stoichiometry has been proposed for the complexes. Based on the significant enhancement of absorption intensity of clomipramine, a sensitive UV spectrophotometric methods with high sensitivity and selectivity were developed for determination of substance in bulk aqueous solution in the presence of β‐CD and HP‐β‐CD. The apparent association constant of the complex was 9.42 · 10³ mol^?1 L and 9.58 · 10³ mol^?1 L and the linear range was 17.6–70 µg mL^?1 with a correlation coefficient of 0.9997 and a relative standard deviation (R.S.D.) of 0.97% and 1.02% using β‐CD and HP‐β‐CD, respectively. There was no interference from the excipients normally used in tablets and capsules. The proposed methods were successfully applied to the analysis of clomipramine in pharmaceuticals with satisfactory results.