Effect of surfactants on temperature-dependent self-assembling property of copolyethylenimine/cinnamic acid aqueous mixture

The transmittance of polyethylenimine (PEI)/cinnamic acid (CA) aqueous mixture was close to zero at 20–40°C, and it began to increase around 40°C due to the disassembling of the self-assembly of the PEI/CA conjugate. As the concentration of sodium dodecyl sulfate (SDS) increased, the increasing rate of the transmittance decreased and the onset temperature increased, indicating that the self-assembly of the PEI/CA conjugate became more stable against heat with the aid of SDS. Tween 20 could also suppress the thermally induced disassembling of the self-assembly, possibly because poly(ethylene oxide) chains of the surfactant could be entangled with the PEI chains. Dodecyltrimethyl ammonium bromide (DTAB) did not have an effect on the temperature-dependent self-assembling phenomena as much as SDS and Tween 20 did. The interfacial tension of the PEI/CA/SDS aqueous mixture and that of the PEI/CA/Tween 20 aqueous mixture at 70°C were lower than the respective tensions observed at 25°C. On the contrary, the interfacial tension of the PEI/CA/DTAB aqueous mixture at 70°C was higher than that observed at 25°C, possibly because the PEI/CA conjugate could lose its surface activity at the higher temperature due to the adsorption of DTAB on CA molecules.     

A convenient synthesis of dihydrocoumarins from phenols and cinnamic acid derivatives

A facile procedure for synthesis of dihydrocoumarin derivatives was described. Although the yield of the products in the reaction of phenols with acrylates in trifluoroacetic acid in the presence of Pd(OAc)₂ giving coumarins was found to be very low, dihydrocoumarin derivatives were obtained in good to high yields in the absence of Pd(OAc)₂ when ethyl cinnamates bearing electron-donating groups were employed in this reaction.     

BTISA-catalyzed Friedel-Crafts bimolecular cyclization of cinnamic acid under superelectrophilic solvation conditions

Friedel-Crafts bimolecular cyclizations of cinnamic acid and cinnamoyl chloride with aromatic compounds in strong and superstrong acids in present of 1 mol% BTISA were investigated. It was demonstrated that catalytic amounts of this new superacid have essential effect on such type of reactions. Its use makes possible the preparation of indanones with quantitative yields.     

Purification of hydroxyanthraquinones and cinnamic acid from the roots of Rheum officinale Baill

A chromatographic method for isolation and purification of chemical constituents from the well-known traditional Chinese drug Da-huang (roots of Rheum officinale Baill.) was established by using 12% cross-linked agarose gel, Superose 12, as the separation media. A two-step separation procedure is employed. Sixty five percent methanol was used as the eluent for separation of cinnamic acid, rhein, physcion and emodin form Da-huang crude extract. The fraction containing aloe-emodin and chrysophanol was then separated by using 55% methanol containing 0.5% acetic acid as the eluent. As a result, cinnamic acid and five kinds of hydroxyanthraquinones including rhein, aloe-emodin, chrysophanol, physcion and emodin were obtained. The retention behavior of hydroxyanthraquinones on Superose 12 was also studied. The retention of hydroxyanthraquinones on Superose 12 is based on a mixture of hydrogen bonding and hydrophobic interactions between the hydroxyl groups of the hydroxyanthraquinones and the residues of the cross-linking reagents used in the manufacturing process of Superose 12.     

Graphene‐sensitized microporous membrane/solvent microextraction for the preconcentration of cinnamic acid derivatives in Rhizoma Typhonii

A novel graphene‐sensitized microporous membrane/solvent microextraction method named microporous membrane/graphene/solvent synergistic microextraction, coupled with high‐performance liquid chromatography and UV detection, was developed and introduced for the extraction and determination of three cinnamic acid derivatives in Rhizoma Typhonii. Several factors affecting performance were investigated and optimized, including the types of graphene and extraction solvent, concentration of graphene dispersed in octanol, sample phase pH, ionic strength, stirring rate, extraction time, extraction temperature, and sample volume. Under optimized conditions, the enrichment factors of cinnamic acid derivatives ranged from 75 to 269. Good linearities were obtained from 0.01 to 10 μg/mL for all analytes with regression coefficients between 0.9927 and 0.9994. The limits of quantification were <1 ng/mL, and satisfactory recoveries (99–104%) and precision (1.1–10.8%) were also achieved. The synergistic microextraction mechanism based on graphene sensitization was analyzed and described. The experimental results showed that the method was simple, sensitive, practical, and effective for the preconcentration and determination of cinnamic acid derivatives in Rhizoma Typhonii.     

Solubilities of cinnamic acid esters in binary mixtures of ionic liquids and organic solvents

The solubilities of three cinnamic acid esters, namely, methyl ferulate, methyl p-coumarate, and methyl sinapate, have been measured in mixed solvent systems of tert-butanol with 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIM][PF₆]), 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF₄]) and 1-methyl-3-octyl-imidazolium tetrafluoroborate ([OMIM][BF₄]) at 303.15 and 321.15 K, and in mixed solvent systems of ethyl acetate with [BMIM][BF₄] and [OMIM][BF₄] at 303.15 K. In eight cases, out of the 22 data sets, an additive behaviour of the solubility was observed, positive deviations from additivity were observed in six cases, a positive synergistic effect in five cases, and, finally, negative deviations from additivity in the remaining three cases. Prediction of the solubilities of the solutes in the various ternary systems was performed with the NRTL and UNIQUAC activity coefficient models. The binary interaction parameters of the models between solute and solvent molecules were taken from the literature. When the parameters between the solvent molecules are fitted to literature data, satisfactory predictions are not always obtained. On the other hand, very good predictions are obtained when only one of the two interaction parameters between the two solvent molecules is fitted to one single point of the solubility isotherm and the other interaction parameter is set equal to zero.     

寡核苷酸链靶向性载体乳糖化聚乙烯亚胺的合成及糖量测定

应用特殊设计的寡核苷酸链纠正点突变是上世纪90年代中后期逐渐发展起来的一项分子生物学新技术。运用该技术能够在基因组碱基序列中任意位点纠正或引入一个指定的碱基。研究人员利用不同的生物材料,如易处理的酵母菌组织、哺乳动物细胞、动物模型以及植物细胞等都开展了广泛的     

Polydopamine‐coated magnetic molecularly imprinted polymer for the selective solid‐phase extraction of cinnamic acid,ferulic acid and caffeic acid from radix scrophulariae sample

We describe novel cinnamic acid polydopamine‐coated magnetic imprinted polymers for the simultaneous selective extraction of cinnamic acid, ferulic acid and caffeic acid from radix scrophulariae sample. The novel magnetic imprinted polymers were synthesized by surface imprinting polymerization using magnetic multi‐walled carbon nanotubes as the support material, cinnamic acid as the template and dopamine as the functional monomer. The magnetic imprinted polymers were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The results revealed that the magnetic imprinted polymers had outstanding magnetic properties, high adsorption capacity, selectivity and fast kinetic binding toward cinnamic acid, ferulic acid and caffeic acid. Coupled with high‐performance liquid chromatography, the extraction conditions of the magnetic imprinted polymers as a magnetic solid‐phase extraction sorbent were investigated in detail. The proposed imprinted magnetic solid phase extraction procedure has been used for the purification and enrichment of cinnamic acid, ferulic acid and caffeic acid successfully from radix scrophulariae extraction sample with recoveries of 92.4–115.0% for cinnamic acid, 89.4–103.0% for ferulic acid and 86.6–96.0% for caffeic acid.     

pH- and temperature-dependent release from cationic vesicles coexisting with copolymer of N-isopropylacrylamide and methacrylic acid

Vesicles containing rhodamine B were prepared by evaporation and hydration method using N-[3-(dimethylamino)propyl]-octadecanamide (DMAPODA) and stearic acid (SA). The vesicles were multi-lamellar on optical and electron micrographs. The mean size of vesicle was 807.9 nm and the values markedly increased by the addition of copolymers of N-isopropylacrylamide (NIPAM) and methacrylic acid (MAA) (P(NIPAM-co-MAA)), possibly due to electrostatic interactions between the cationic vesicle and the anionic copolymer. The release of rhodamine B from the vesicles for 20 h was 50–60% at neutral pHs and the values increased up to 93.1% when pH decreased to 3. The increased release is possibly because the salt bridge formed between DMAPODA and SA was broken down at the acidic pH, leading to the disintegration of the vesicles. On the other hand, the release was not as sensitive to temperature as it was to pH. The salt bridge seemed to be stable at the temperatures of the release experiments (23 °C, 33 °C and 43 °C). P(NIPAM-co-MAA) was added to the suspension of the vesicle and the release was investigated with varying pHs and temperatures. The copolymer was pH- and temperature-sensitive in terms of the turbidity change of its solution. Nevertheless, the copolymer was found to have little effect on the pH- and temperature-dependent release of the vesicles.     

Solvent-free synthesis of 4-aryl-3,4-dihydrobenzopyran-2-ones via [3+3] cyclocoupling of phenols with cinnamic acid catalyzed by molecular iodine

Molecular iodine was used as a catalyst in the [3+3] cyclocoupling of phenols and cinnamic acids which proceeds via a tandem esterification-hydroarylation process at 120-130 °C under solvent-free conditions. Substituted 4-aryl-3,4-dihydrobenzopyran-2-ones were obtained in good yields.     

Highly selective hydroarylation of propiolic acid derivatives using a PtCl2/AgOTf catalytic system

Hydroarylation of propiolic acid derivatives with arenes in trifluoroacetic acid efficiently proceeded in the presence of PtCl₂/AgOTf catalyst to give cis-cinnamic acid derivatives in good to high yields. This PtCl₂/AgOTf-catalyzed reaction did not afford any 4-arylbuta-1,3-diene-1,3-dicarboxylic acid derivatives formed by Pd(OAc)₂-catalyzed hydroarylation. The specific optimization of the catalytic hydroarylation and application to electron-rich arenes are reported.     

Simultaneous determination of harpagoside and cinnamic acid in rat plasma by high-performance liquid chromatography: application to a pharmacokinetic study

Radix Scrophulariae (Xuanshen) is one of the famous Chinese herbal medicines widely used to treat rheumatism, tussis, pharyngalgia, arthritis, constipation, and conjunctival congestion. Harpagoside and cinnamic acid are the main bioactive components of Xuanshen. The purpose of this study was to develop an HPLC–UV method for simultaneous determination of harpagoside and cinnamic acid in rat plasma and investigate pharmacokinetic parameters of harpagoside and cinnamic acid after oral administration of Xuanshen extract (760 mg kg⁻¹). After addition of syringin as internal standard, the analytes were isolated from plasma by liquid–liquid extraction. Separation was achieved on a Kromasil C₁₈ column, and detection was by UV absorption at 272 nm. The described assay was validated in terms of linearity, accuracy, precision, recovery, and limit of quantification according to the FDA validation guidelines. Calibration curves for both analytes were linear with the coefficient of variation (r) for both was greater than 0.999. Accuracy for harpagoside and cinnamic acid ranged from 100.7–103.5% and 96.9–102.9%, respectively, and precision for both analytes were less than 8.5%. The main pharmacokinetic parameters found for harpagoside and cinnamic acid after oral infusion of Xuanshen extract were as follows: C _max 1488.7 ± 205.9 and 556.8 ± 94.2 ng mL⁻¹, T _max 2.09 ± 0.31 and (1.48 ± 0.14 h, AUC_0–24 10336.4 ± 1426.8 and 3653.1 ± 456.4 ng h mL⁻¹, 11276.8 ± 1321.4 and 3704.5 ± 398.8 ng h mL⁻¹, and t _1/2 4.9 ± 1.3 and 2.5 ± 0.9 h, respectively. These results indicated that the proposed method is simple, selective, and feasible for pharmacokinetic study of Radix Scrophulariae extract in rats. Figure Radix Scrophulariae     

Synthesis and electrochemistry of tetrakis(7-coumarinthio-4-methyl)-phthalocyanines,and preparation of their cinnamic acid and sodium cinnamate derivatives

Novel water soluble free-base, Zn(II) and Co(II) metallo phthalocyanines with four cinnamic acid moieties were prepared from the corresponding tetrakis(7-coumarinthio-4-methyl)-phthalocyanine by the lactone ring opening reaction. The new compounds were purified and characterized by elemental analysis, ¹H NMR, Maldi-TOF, FT-IR and UV–Vis spectral data. Cyclic and differential pulse voltammetry and in situ spectroelectrochemistry of the 2,9,16,23-tetrakis(7-coumarinthio-4-methyl) substituted free-base 1a, Zn(II) 1b and Co(II) 1c phthalocyanines, employed as the starting compounds have been studied. This allowed us not only to identify metal- and phthalocyanine ring-based redox processes of the complexes, but also the effect of aggregation on these processes.     

Cinnamic acid amides and lignanamides from Aptenia cordifolia

Examination of the hydroalcoholic extract of the leaves of Aptenia cordifolia has afforded three cinnamic acid amides and two lignanamides. Structures were established on the basis of spectroscopic data, including 2D-NMR analyses.     

Sodium dodecyl sulfate—polyethyleneimine—water system. Self-organization and catalytic activity

Concentration boundaries within which polymer—colloid structures exist in a sodium dodecyl sulfate—polyethyleneimine—water system were determined. The catalytic effect of this composition was found for the hydrolysis of phosphonic acid esters. The found acceleration of hydrolysis up to 25-fold is caused by reagent concentrating in a catalytic complex.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 630–638, March, 2005.     

A simple and convenient synthesis of 3-[5-(trifluoromethyl)-1,2,3-triazol-4-yl]cinnamic acids from 4-aryl-6-(trifluoromethyl)-2H-pyran-2-ones and sodium azide

4-Aryl-6-(trifluoromethyl)-2H-pyran-2-ones and ethyl 4-aryl-6-(trifluoromethyl)-2-oxo-2H-pyran-3-carboxylates react with sodium azide to produce highly functionalized CF₃-1,2,3-triazoles: 3-[5-(trifluoromethyl)-1,2,3-triazol-4-yl]cinnamic acids and monoethyl esters of [5-(trifluoromethyl)-1,2,3-triazol-4-yl]arylmethylidene malonic acids.     

An investigation of the photo-reactive and unreactive polymorphs of o -ethoxy cinnamic acid and of its photodimer

Detailed X-ray crystallographic investigation of the reactive α- and the unreactive γ-polymorphs ofo-ethoxy cinnamic acid has been carried out along with that of the photodimer, α-truxillic acid. The molecule is quite planar in the α-form, but in the γ-form, the side groups deviate significantly from the plane of the benzene ring. The carboxylic groups form normal cyclic hydrogen bonds in the α-form and near-symmetric hydrogen bonds in the γ-form. The infrared spectrum of the α-form shows the characteristic features of the cyclic dimer, but that of the γ-form is entirely different, marked by the absence of the O-H stretching band in the 3000 cm^-1 region. Charge density analysis throws some light on the structure and reactivity of the molecule in the two forms. The near-symmetric hydrogen bond in the γ-form is ionic and appears to restrict conjugation by way of distorting the molecule. This unusual feature keeps the cinnamoyl double bonds away from each other, rendering it photochemically unreactive. In the α-form, however, the double bonds have a closer approach. The cyclobutyl ring of the photodimer consists of weak single bonds, with the new pair being slightly longer.     

Laser Raman spectroscopic study of photoreaction dynamics in p -chloro cinnamic acid crystal

Raman phonon spectroscopy has been used to study photodimerization reaction inp-chloro cinnamic acid (pCCA) crystal. The β-form of the crystal yields the 4,4′-dichloro-β-truxinic acid dimer. Six distinct low frequency phonon bands are observed in thepCCA monomer crystal. On reaction progress, these bands show a monotonic shift to lower frequencies and broaden out. Finally, in the dimer crystal the phonon spectrum shows two weak broad bands. These results suggest that the reaction is homogeneous in the initial stages and, as the product concentration increases, the lattice becomes highly disordered. The reactant and the product were characterised by infrared and Raman spectroscopy. The disappearance of aliphatic C=C bond stretching vibration and appearance of cyclobutane ring deformation and cyclobutane ring-breathing vibrations on reaction confirm photodimerization by cyclobutane ring formation. The large Stoke's shift between the absorption and emission band suggest strong exciton-phonon coupling in the monomer lattice. This reaction seems to be phonon-mediated.     

pH- and Ionic-Strength-Induced Structural Changes in Poly(acrylic acid)-Lipid-Based Self-Assembled Materials

Summary: The effect of a polyanion introduced as a lipid conjugate (poly(acrylic acid)- dimyristoyl-sn-glycero-3-phosphoethanolamine, PAA-DMPE) on the structure of a self-assembled, biomembrane mimetic has been evaluated using synchrotron small-angle X-ray scattering (SAXS). At high grafting density (8–11 mol.%), the PAA chains were found to produce significant changes in structure in response to changes in pH and electrolyte composition. At low pH and in the absence of salt (NaCl), the neutral PAA chains adopt a coil conformational state that leads to the formation of a swollen lamellar structure. Upon the addition of salt at low to intermediate pH values, two lamellar phases, a collapsed and an expanded structure, coexist. Finally, when the polymer is fully ionized (at high pH), the extended conformation of the polymer generates a cubic phase. The results of this study contribute to an understanding of how polyelectrolytes may ultimately be harnessed for the preparation of self-assembling materials responsive to external stimuli.