X–Ray Photoelectron Spectra and Electronic Energy Structure of Tetragonal Cu x Ni1-xTi Alloys

The electronic energy structure (EES) of Cu_0.8Ni_0.2Ti and Cu_0.6Ni_0.4Ti alloys, stoichiometric CuTi compound with a tetrahedral CuTi–type crystal lattice, and cubic NiTi was studied experimentally and theoretically. The experimental study of valence band EES was carried out by Xray photoelectron spectroscopy (XPS). The EES of both the stoichiometric compounds and the alloys was calculated using the cluster version of multiple scattering theory in a selfconsistent field approximation. The calculation and experimental results are in good agreement. The major contribution to XPS of the studied compounds is from the d states of copper and nickel. The specifics of chemical bonding in the compounds are discussed. The EES of tetragonal Cu—Ni—Ti alloys is modeled.     

Synthesis and X‐Ray Analysis of a New [6]Helicene

A new disubstituted hexahelicene derivative 3 bearing methoxy functions at positions 3 and 14 has been prepared in racemic form through a Heck reaction followed by photocyclodehydrogenation. Suitable crystals of rac‐3 were analyzed by X‐ray crystallography and showed similar geometry to the structure of hexahelicene itself. Deprotection of 3 using boron tribromide led to 3,14‐dihydroxyhexahelicene 4 in quantitative yield. The complexation of transition metal atoms seemed to be quite possible by these two bidentate hexahelicene derivatives.     

X-Ray Photoelectron Spectroscopic Study on the Synthesis of Copper Sulphide in LB Films( Ⅱ )

The present paper covers the formation process of copper sulphide in copper stearate Langmuir-Blodgett films studied carefully by XPS. The further identification of sulfur species and the examination of its change in the reaction have been made. Also the formation mechanism of sulfur species in the special microenvironment-LB films is discussed.     

Synthesis of 4‐Substituted‐ and 1,4‐Disubstituted‐4‐Hydroxypyrrolidin‐2‐ones

This report describes the synthesis of 4‐substituted‐ and 1,4‐disubstituted‐4‐hydroxypyrrolidin‐2‐ones by cyclization of intermediate γ‐aminoesters prepared from alkylbenzylamines, α‐bromoketones, and lithio ethyl acetate.     

Synthesis and X‐Ray Study of Single Crystals of K5(Cd0.5Zr1.5)(MoO4)6 Triple Molybdate

Single crystals of K₅(Cd_0.5Zr_1.5)₂(MoO₄)₆ molybdate have been grown. Its composition and crystal structure have been established from Xray diffraction data CAD4 automatic diffractometer, MoK radiation, 940 F(hkl), R = 0.0234. The crystals have a trigonal unit cell a = b = 10.624(1), c = 37.694(6), V = 3684.5(8)³, and space group R3c. The 3D mixed framework of the molybdate structure is formed by two kinds of Mo tetrahedra and (Cd, Zr) octahedra joined by shared O vertices. The large cavities in the framework are occupied by K atoms of three kinds. The distribution of Cd²⁺ and Zr⁴⁺ cations over two crystallographic positions has been refined.     

Spectroscopic Study on the Interaction between Bovine Serum Albumin and Tween‐20

The interaction between nonionic surfactant Tween-20 and bovine serum albumin (BSA) is studied in Tris‐HCl buffer solution by spectroscopic methods. The intrinsic fluorescence of BSA is quenched by the addition of Tween‐20. The UV‐visible absorption spectra and the synchronous fluorescence spectra show that the addition of Tween‐20 changes the polarity of the environment around tryptophan (trp) residues of BSA. The fraction of trp residues on the surface of BSA with and without Tween- 20 is calculated via I^? quenching experiments.     

Detection of Intermediate during Electrochemical Polymerization of Azure A and X‐ray Photoelectron Spectroscopy of Poly(azure A)

The electrochemical polymerization of azure A has been investigated by the rotating ring‐disk electrode (RRDE) and the X‐ray photoelectron spectroscopy (XPS). The electrolysis of azure A was studied in the pH region of 1.0 and 12.0. The results from the RRDE experiments show that the electrochemical polymerization of azure A was performed by two steps, i.e., oxidation of azure A and followed by polymerization. The intermediates generated at the disk were detected at the ring electrode in the ring potential region of ?0.2–0.20 V (vs. Ag/AgCl reference electrode). The collection efficiencies of the intermediates increase with decreasing the ring potential as well as increasing the rotation rate of the RRDE. Thus, the intermediate is to carry a positive charge species and not too stable. The results from the XPS experiments show that the anions can be doped into poly(azure A) film and be dedoped from it during oxidation and reduction processes.     

Stereo‐ and Regioselective Thiolysis of 1,2‐Epoxides in Water

A simple, efficient, stereoselective, and highly regioselective procedure for the synthesis of β‐hydroxy sulfides by thiolysis of various 1,2‐epoxides in water as a solvent, using no catalyst and under very mild conditions, is described.     

Convenient Synthesis of Pyrrole‐ and Indolecarboxylic Acid tert‐Butylesters

Abstract

The tert‐butylesters of pyrrole‐ and indolecarboxylic acids are readily accessed by reacting the appropriate carboxylic acids with N,N‐dimethylformamide di‐tert‐butyl acetal.     

Effect of Emulsification Method on the Properties of Lecithin‐ and PGPR‐Stabilized Water‐in‐Oil‐Emulsions

Water‐in‐oil (w/o) emulsions were prepared with phosphatidylcholine‐depleted lecithin or polyglycerol polyricinoleate (PGPR) as emulsifying agents. The effect of different laboratory emulsification devices and the effect of sodium chloride on particle size distribution, coalescence stability, and water droplet sedimentation were investigated. The properties of lecithin‐stabilized w/o emulsions were found to depend more strongly on the emulsifying method than those prepared with PGPR. The rotor‐stator system was not suitable for preparing stable w/o emulsions with lecithin. Whereas the addition of salt was essential to achieve coalescence‐stable emulsions prepared with PGPR, the presence of NaCl favored the coalescence of water droplets and phase separation in emulsions containing lecithin.     

Synthesis and Characterization of Alkyl and Aryl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amines: X‐Ray Structures of Ethyl and Cyclohexyl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amine

Abstract

We have synthesized and characterized a series of alkyl and aryl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amines through a high‐yield, three‐step procedure starting from 4‐methylquinolin‐2‐ol. Nitration using concentrated nitric/sulfuric acids, followed by chlorination in phosphorus oxychloride, yielded 2‐chloro‐4‐methyl‐6‐nitro‐quinoline. All of the intermediates and aminated products have been characterized by multinuclear (¹H and ¹³C) NMR spectroscopy, elemental analysis, and, in the case of the two title compounds (ethyl and cyclohexyl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amine), a single crystal X‐ray structure was obtained to verify the nature of the new materials.     

Spectroscopic Study of Hedamycin – DNA Interaction

Summary: Binding of hedamycin, a member of the antitumour antibiotics pluramycin class, to calf thymus DNA has been studied using UV-Vis absorption spectroscopy. The results have been rationalized in terms of several literature models: Wolfe, Benesi-Hildebrand, Scott and Scatchard.     

Thermolysis and [3+2]‐Cycloaddition Reactions of 2,3‐Diferrocenyl‐ and 2,3,‐Diruthenocenylcyclopropenones

Abstract

2,3‐Diferrocenyl‐ and 2,3‐diruthenocenylcyclopropenone undergo thermolysis at ～180°C with opening of the small ring via ketenocarbenes. Intramolecular transformation of the latter occurs with elimination of CO to yield dimetallocenylacetylenes. Alternatively, they enter into 1,3‐dipolar cycloaddition reactions with C≡C or C?C multiple bonds to give cyclopentadienone or cyclopentenone derivatives, respectively.     

Structure and Conformational Mobility of 4′‐Pentyl‐4‐Cyanobiphenyl from IR Spectroscopic Data

The structure and conformational mobility of 4pentyl4cyanobiphenyl in the liquid and liquidcrystal states were investigated by means of IR spectroscopy (experiment and theory). IR absorption spectra in the frequency range 400–4000 cm^-1 were measured in the temperature range 26–150°. Theoretical simulation of the IR spectra was performed using the fragment approach. A comparison of theoretical and experimental spectra showed that the examined samples were mixtures of conformers; characteristics of the most probable conformers are given. Temperaturerelated changes in the spectrum are due to the conformational mobility of the molecules, which is not high in the temperature range considered.     

Spectroscopic Study of the Interactions of Buflomedil to Serum Albumin and β-Cyclodextrin

The effects of buflomedil (BFM), a novel cerebrovascular medicine, on serum albumin and the feasibility of ??-cyclodextrin (??-CD) acting as a controlled releaser for BFM were investigated by molecular spectroscopy methods, including fluorescence emission, UV?Cvisible absorption, Fourier transform infrared (FT-IR), synchronous and three-dimensional fluorescence spectroscopies. The interaction of BFM with bovine serum albumin (BSA) was analyzed by fluorescence quenching and it was found that BFM had reacted with BSA in the ground state and had affected the secondary structure of BSA. The observed binding constant K _b, the number of binding sites n, the distance r between donor (BSA) and acceptor (BFM), the enthalpy change (??H ^?? ), Gibbs energy change (??G ^?? ) and entropy change (??S ^?? ) at different temperatures were calculated. The inclusion reaction between ??-CD and BFM was explored by the Lineweaver?CBurk equation. The inclusion constants and the thermodynamic parameters were determined. The mechanism of the inclusion reaction was discussed and the controlled release characteristics of ??-CD to BFM were considered at the molecule level.     

Methods for the Preparation of Micro‐ and Nanocrystals of Urethane‐Substituted Polydiacetylenes

Urethane‐substituted polydiacetylene (PDA) crystals of bis(ethyl)‐urethane of 5,7‐dodecadiyne‐1,12‐diol (poly(ETCD)) with micronscale and nanoscale dimension were fabricated by either ultrasonication, surfactant addition or vapor phase processing approaches. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to evaluate the sizes and the shapes of the obtained poly(ETCD) microcrystals. Dynamic light scattering (DLS) was performed to investigate in situ size distributions of these crystals in aqueous suspension. A UV/Visible/NIR Spectrometer (UV/Vis/NIR) was used to study the electronic absorption of the poly(ETCD) microcrystals. Thermochromic phenomena for poly(ETCD) crystals still exist after their dimension was decreased to the nanoscale.     

Preparation of 1‐Arylideneamino‐ and 1‐Alkylideneamino‐3‐phenoxypropan‐2‐ol N‐Oxides—A New Type of Nitrones

Abstract

The reaction of phenylglycidyl ether with hydroxylamine was evaluated, and the prepared 1‐hydroxyamino‐3‐phenoxypropan‐2‐ol was used for the 1‐arylideneamino‐ and 1‐alkylideneamino‐3‐phenoxypropan‐2‐ol N‐oxides syntheses. The title nitrones were tested as antioxidants in biological systems.     

Synthesis and Characterization of Water‐Soluble Cellulose Derivatives with Thermo‐ and pH‐Sensitive Functional Groups

A series of water‐soluble cellulose derivatives with thermo‐ and pH‐sensitive properties were prepared in aqueous solutions by the graft copolymerization of N‐isopropylacrylamide (NIPAAm) on carboxymethylcellulose (CMC). Ceric ammonium nitrate (CAN) was used in combination with nitric acid as the initiator system. The effects of various factors such as CAN concentration, NIPAAm and CMC amounts as well as reaction temperature on the grafting percentage and efficiency were studied. The resultant cellulose derivatives were characterized with respect to their structure and aqueous solution properties by IR spectra, thermogravimetric analyses and optical transmittance measurements.     

Application of Odorless Thiols for the Cleavage of 2‐ and 4‐Nitrobenzenesulfonamides

Several odorless or faint‐smelling thiols were tested to cleave 2‐ and 4‐nitrobenzenesulfonyl groups, which are widely utilized for selective protection and activation of amines. p‐Mercaptobenzoic acid (7) was found to be the most useful thiol for cleaving the o‐ and p‐nosyl groups in terms of ease of separation of the product from the workup residue, reaction temperature, and reaction time.     

Synthesis of Anomerically Pure,Furanose‐Free α‐Benzyl‐2‐amino‐2‐deoxy‐d‐altro‐ and d‐manno‐pyranosides and Some of Their Derivatives

The anomerically pure benzyl α‐d‐glycoside of 2‐amino‐2‐deoxy‐mannopyranoside was synthesized from d‐glucopyranose via 2‐amino‐2‐deoxy‐d‐altrose intermediates. Unlike the direct synthesis from mannosamine in the literature, our method provides furanose‐free products. A new method for the preparation of cis‐2,3‐oxazolidinones of 2‐amino‐2‐deoxy‐sugars was developed. A selective removal of the glycosidic benzyl group in the presence of 4,6‐O‐benzylidene protection was developed, which may provide new routes for the synthesis of oligosaccharides. Furanose‐free derivatives of α‐benzyl‐2‐amino‐2‐deoxy‐mannopyranuronic acids synthesized here offered possibilities for direct comparisons to prior literature preparations.