In situ study of electrocopolymerization of acrylamide,formaldehyde, and N,N′-methylenebisacrylamide

An apparatus and procedure for real-time in situ investigations of monomer electropolymerization in solution using optical microscopy with differential interference and phase contrast have been designed. The kinetics of electropolymerization of an acrylamide-formaldehyde monomer mixture in aqueous solution has been studied. An induction period of electropolymerization was fixed and evaluated for the first time. Growth of the polymer film after disconnection has been visualized. The dynamics of this phenomenon is evaluated, and possible reasons are discussed. Anisotropic mechanical stresses, arising in the polymer film during electropolymerization, have been found and characterized. The mechanism that is responsible for the formation of a dense near-cathode layer has been revealed. The formation of a zinc sublayer during electropolymerization has been examined. Reasons for the roughness of the near-electrode surface of the polymer film and for high adhesion of the electrodeposited polymer film to the metal have been established.     

2, 3, 7-三羟基-9-间羟基苯基荧光酮的合成及其 分析性能的研究

研究合成了新试剂2,3,7-三羟基-9-间羟基苯基荧光酮(简称m-HPF)。测定了试剂各级酸离解常数。研究了试剂的化学发光性能和试剂与金属离子的显色行为。结果表明,只有Co^2^+离子对m-HPF-H~2O~2体系有较强的催化发光作用;在表面活性剂存在下,试剂与许多离子都呈灵敏的显色反应。用Huckel分子轨道法(HMO)计算了中性分子及各离子构式的π电子分布,对离解常数进行了归属。     

Premalbrancheamide: synthesis, isotopic labeling, biosynthetic incorporation, and detection in cultures of Malbranchea aurantiaca

An advanced metabolite, named premalbrancheamide, involved in the biosynthesis of malbrancheamide (1) and malbrancheamide B (2) has been synthesized in double (13)C-labeled form and was incorporated into the indole alkaloid 2 by Malbranchea aurantiaca. In addition, premalbrancheamide has been detected as a natural metabolite in cultures of M. aurantiaca. The biosynthetic implications of these experiments are discussed.     

Theoretical Study on the Structure and Stability of Si5X （X = Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl） Clusters

1 INTRODUCTION In the later 60s of last century, silicon substituted for germanium to present as mainstream in semicon- ductor. The semi-conductive devices made by silicon have many advantages, for example, refractory pro- perty, high radioresistance, simple and stable process- ing technic, high machinability and low cost. So it was widely used to manufacture large power appara- tuses, for instance, digit and linear integrated circuit, large scale integrated circuit (LSI), etc. Thus, th…     

PHOTOCHEMICAL REACTIONS OF THYMINE, URACIL, URIDINE, CYTOSINE AND BROMOURACIL IN FROZEN SOLUTION AND IN DRIED FILMS*

Abstract— The photochemistry of uracil, uridine, cytosine, thymine and broinouracil has been investigated in frozen aqueous solution and in dried films. Essentially the same photoproducts were obtained in the two conditions; however, the yield of photoproducts was considerably greater in frozen solution. Uracil forms a dimer which can exist in two forms. Some kinetic data are presented for the interconversion of these two forms, The mixed dimer of thymine and uracil can also exist in two forms. Uridine forms only one acid stable photoproduct and does not appear to form mixed photoproducts under the conditions used. Two new photoproducts of thymine other than the dimer are described. Cytosine was at first considered to be completely inert hut using more sensitive detecting equipment it has recently been found to form uracil dinier as a result of dinierization and deamination. The most remarkable response was shown by bromouracil. When irradiated by itself it formed no photoproducts but when irradiated in the presence of uracil, uridine, cytosine or NaOH it formed many photoproducts. Most of these products were devoid of bromide, but two still contained bromine. One of these has been identified as the mixed dimer of uracil and bromouracil while the other has been tentatively identified as the dimer of bromouracil. Dimers of thymine or bromouracil were not formed by X-rays.     

Three-component condensation of trifluoromethyl-substituted cyanovinylphosphonates,arylamines, and ketones and cytotoxic activity of products thus obtained

A three-component condensation of trifluoromethyl-substituted cyanovinylphosphonates, arylamines, and ketones (acetone, cyclopentanone, or cyclohexanone) has been studied. A possibility of using trifluoromethyl-substituted cyanovinylphosphonates as precursors of 1,4-dihydropyridines, 4,5,6,7-tetrahydro-1H-cyclopenta[b]pyridines, 1,4,5,6,7,8-hexahydro-quinolines, and 1,4,4a,5,6,7-hexahydroquinolines, modified with both trifluoromethyl and di-ethoxyphosphoryl groups, has been demonstrated. Using X-ray diffraction analysis, it was found that in some cases of the three-component condensation under study a mixture of 1-aryl-2-amino- and 2-arylamino-substituted products was formed. Migration of the multiple bond onto the ring fused with the dihydropyridine ring has been inferred from the NMR spectra and X-ray diffraction data. Cytotoxic activity of some compounds synthesized has been studied in the US National Cancer Institute.     

Fibril-like aggregate formation of peptide carboxylate Langmuir films analyzed by surface pressure, surface dipole moment, and infrared spectroscopy

The fibril formation process of a synthetic peptidolipid compound in a Langmuir monolayer at the air-water interface has been analyzed by surface pressure and surface dipole moment-area isotherms, followed by infrared spectral analysis of related Langmuir-Blodgett films. Thus far, the analysis of randomly oriented molecular assemblies has been a difficult matter, especially for spectroscopic measurements. In the present study, the Langmuir film isotherms were discussed in detail, and they have readily been correlated to the infrared spectra. For the spectral analysis, infrared multiple-angle incidence resolution spectroscopy (MAIRS) was employed, which was compared to the results by conventional techniques. Since the peptide assemblies greatly responded to a metal surface, the reflection-absorption technique was not useful for our analysis. Instead, MAIRS was found to be powerful to reveal the anisotropic structure of the Langmuir films, and a disordered molecular architecture has been revealed via the molecular orientation analysis. As a result, the fibril-like aggregation formation process during the monolayer compression, which was suggested by previous topographical study, has been found to be due to the stiff domain formation in the Langmuir films.     

Photocatalysed degradation of a herbicide derivative, Dinoterb, in aqueous suspension

The photocatalytic degradation of a herbicide derivative, Dinoterb (1), has been investigated in aqueous micellar solution in the presence of titanium dioxide (TiO₂) and air as a function of irradiation time under a variety of conditions using UV and HPLC analysis techniques. The degradation kinetics was studied under different conditions such as different types of TiO₂, catalyst concentration, substrate concentration and reaction pH in the presence of air. The photocatalyst Degussa P25 was found to be more efficient catalyst as compared to other photocatalysts tested. The model compound was found to degrade more efficiently under neutral pH as compared to acidic and alkaline pH. GC/MS analysis of the irradiated samples indicate the formation of 2-isopropyl-4,6-dinitro-phenol as by-product which has been characterized on the basis of molecular ion and mass fragmentation pattern. A probable pathway for its formation has been proposed.     

Synthesis, molecular structure, spectroscopic studies and second-order nonlinear optical behaviour of N,N'-(2-hydroxy-propane-1,3-diyl)-bis(5-nitrosalicylaldiminato-N,O)-copper(II)

N,N'-(2-Hydroxy-propane-1,3-diyl)-bis(5-nitrosalicylaldiminato-N,O)-copper(II) has been synthesized. The crystal structure has been determined by X-ray diffraction analysis, and linear optical characterization has been determined by UV-vis spectroscopy. It was found that the molecule under investigation has solvatochromic behaviour in the UV region, implying non-zero microscopic first hyperpolarizability. To reveal the microscopic nonlinear optical (NLO) properties, the static first hyperpolarizabilities (beta) and the electric dipole moments (mu) were evaluated by using the ab initio finite field (FF) method. According to the results of the FF calculations, the synthesized compound exhibits non-zero beta values, and it might have microscopic NLO behaviour.     

Studies on the growth, spectral, optical, and thermal aspects of a NLO crystal

Nonlinear optical single crystal l-tryptophan hydrogen selenite (LTHS) has been synthesized by slow evaporation solution growth technique from aqueous solution at ambient temperature. The grown nonlinear optical crystals were subjected to single crystal XRD analysis to find the structure parameters. The formation of the product was confirmed from the FTIR and ¹HNMR spectral analysis. The UV–Vis spectral studies showed that the cutoff wavelength for LTHS was less than 400 nm. The thermal behavior of the grown crystals was investigated from thermogravimetry and differential thermal analysis. Its nonlinear optical property has been tested by Kurtz–Perry powder technique using Nd:YAG laser, and the crystal exhibited second harmonic generation property.     

Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.     

Synthesis,structure, and biological evaluation of novel N- and O-linked diinositols

Several O-and N-linked inositols and/or aminoinositols have been prepared by iterative opening of epoxides and aziridines derived from homochiral cyclohexadiene cis-diols. The three inositols and their intermediate conduritols (conduramines) were tested against several glycosidases (alpha- and beta-glucosidase, alpha- and beta-galactosidase, alpha- and beta-mannosidase) in an assay that measured the rate of hydrolysis of p-nitrophenolglycosides rather than the concentration of p-nitrophenolate. Somewhat surprisingly, the best inhibition was seen against beta-galactosidase with several of the compounds. The inositols linked through oxygen or nitrogen were subjected to calcium binding studies performed in NMR experiments. Detailed analysis of the title compounds by NMR spectroscopy has been performed, and full assignments were made. One of the attendant benefits of the preparation of these compounds has been expressed in the design and synthesis of new salen catalysts whose effectiveness has been compared with Jacobsen's catalyst in the epoxidation of styrene.     

Bolineol, a novel co-metabolite of strobilurins A, F and G from Bolinea lutea

A mycelial co-metabolite of strobilurin A, F and G from Bolinea lutea, which we have named bolineol, has been characterised for the first time. Bolineol (methyl 2-hydroxymethyl-3-methyl-6-phenyl-3Z,5E-hexadienoate) has a similar carbon skeleton to strobilurin A but differs in oxidation level. Its structure has been deduced from its spectral characteristics and those of its acetate. The known compound strobilurin F-1 (methyl 2-methoxymethylene-3-methyl-6-(3'-hydroxyphenyl)-3Z,5E-hexadienoate) has been detected in this organism for the first time and converted into its acetate, a new compound, the structure of which was assigned from its spectral data.     

Biomimetic synthesis of carthamin,a red pigment in safflower petals,via oxidative decarboxylation

Carthamin, a natural red pigment derived from safflower, was discovered centuries ago and has been utilized in several industries such as dye, food coloring, and natural medicine industries. Although it has been used since Egyptian times, its structural features were only determined in the mid-1900s when pioneering studies were conducted to elucidate the carthamin structure and assign its stereochemistry. Reproducing the complex biosynthesis of carthamin has been a common research goal since then. However, this has been rendered complex because of the unstable precursors and low yields from the multiple steps involved in the synthesis. Herein, we report the total synthesis of carthamin via a four-step procedure using (S)-C-β-D-glucosylquinochalcone as the starting compound. The synthesis involves mild conditions, short reaction time, and readily available compounds. After de-O-methylation, condensation, oxidative decarboxylation, and saponification, carthamin was obtained in an overall yield of 9.5% through the proposed method.     

Dendrimers Functionalized with Palladium Complexes of N-, N,N-, and N,N,N-Ligands

Pyridine, pyridine imine, and bipyridine imine ligands functionalized by a phenol have been synthesized and characterized, in many cases by X-ray diffraction. Several of these N-, N,N-, and N,N,N,-ligands have been grafted onto the surface of phosphorhydrazone dendrimers, from generation 1 to generation 3. The complexation ability of these monomers and dendrimers towards palladium(II) has been assayed. The corresponding complexes have been either isolated or prepared in situ. In both cases, the monomeric and dendritic complexes have been tested as catalysts in Heck couplings and in Sonogashira couplings. In some cases, a positive dendritic effect has been observed, that is, an increase of the catalytic efficiency proportional to the dendrimer generation.     

3α,7α,12α-三甲基丙烯酰基胆酸甲酯的制备与聚合物特性研究

以甲基丙烯酰氯为酰化试剂，合成了3α，7α，12α-甲基丙烯酰胆酸甲酯(CAME3MA)，研究了CAME3MA的光引发本体聚合和溶液聚合反应，并且对CAME3MA及其聚合物的特性进行了表征．实验表明：CAME3MA的本体光引发聚合转化率随光照时间的延长逐渐增加并达到一个最大值，最终的聚合转化率在36％左右，溶液聚合得到线性聚合物。     

Syntheses, structural properties, and charge-transfer complexes of pyrenophanes

Dithia[3.3](4,9)benzenopyrenophanes carrying various functional groups at the inner position or the outer position of the benzene ring have been prepared. The pyrenophanes with the substituent at the inner position of the opposite benzene ring exhibit the conformation in which the pyrene and the benzene components exist in the parallel manner (parallel conformation). On the contrary the conformation characterized by the perpendicular orientation of the pyrene and the benzene components has been confirmed for the pyrenophanes having the substituent at the outer position of the opposite benzene ring (perpendicular conformation). The NH-pi interaction between the inner amino group on the opposite benzene ring and the pyrene ring was observed. Formation of charge-transfer complexes of the pyrenophanes and tetracyanoethylene (TCNE) was performed. It has been found out that the orientation of two aromatic components and the NH-pi interaction as well as the electronic nature of the substituent on the opposite benzene ring significantly affect characteristics of the charge-transfer complexes in this pyrenophane system.     

Solid-phase combinatorial synthesis of benzothiazoles, benzimidazoles, and benzoxazoles using a traceless linker

New methodology for the solid-phase synthesis of benzothiazoles, benzimidazoles, and benzoxazoles has been developed by using a traceless 4-alkoxy-aniline linker. The desired products were released from the polymer support by imine-exchange process coupled with air oxidation. Combinatorial library consisting of 36 members has been synthesized using this linker. The yields are low to good, which highly depend on the building blocks. Recycling of the polymer support was also investigated.     

Amphiphilic poly-n-vinyl-2-pyrrolidone: Synthesis,properties, nanoparticles

Water-soluble amphiphilic polymers based on N-vinyl-2-pyrrolidone (Amph-PVP) have been synthesized. Amphiphilic diblock polymers have been obtained via a single-step technique. For the synthesized amphiphilic polymers, the critical concentrations of mycelium formation (CCM) have been determined. The structure of the polymers obtained was confirmed by IR and NMR spectroscopy. The critical concentration of micelle formation (CCM) for the synthesized polymers has been found to be in the micromolar range. The fluorescent dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (Dil) was chosen as a model substance for the synthesis of nanoparticles. Micellar particles were obtained via an ultrasonic technique followed by evaporation of the organic solvent (emulsion method).     

DFT-predicted structural,vibrational, and bonding properties of XSiO and X2SiO (X=F,Cl, or Br) molecules

The spectroscopic properties of XSiO (X=F, Cl, or Br) have been predicted using the B3-LYP/6-311+G(2d) level of theory. It has been shown that the halogen atom is Si bonded in a bent structure, with ∠(XSiO) bond angles close to 126°. The binding energy of the halogen with the SiO subunit was calculated to be −80.1, −40.9, and −29.3 kcal/mol for FSiO, ClSiO, and BrSiO, respectively. The harmonic frequencies and isotopic shifts have been calculated. A comparison between XSiO and X₂SiO has also been made. For the X₂SiO (X=F or Cl) compounds, the calculated frequencies are in fair agreement with the available experimental data. Characterization of bonding has been investigated with different approaches (natural bond orbital approach, topological analysis of the charge density, and of the electron localization function ELF). © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1205–1214, 1998