Electroluminescence and Spectral Properties of N9‐Isobutyl‐2‐Oxo‐3‐Phenyl‐3N‐Benzo[F]Chromene‐9‐Sulfonamide

Experimental data on the synthesis and spectral properties (UV, IRFourier, xray photoelectronic, and luminescence spectra) of the sulfonamide derivative of benzocoumarin in an isopropanol solution and in a film applied by thermal vacuum deposition (TVD film) are reported. The use of TVD films of the investigated substance as electroluminophors is shown to be promising.     

Conformational and Structural Analysis of 6‐(4‐Methoxy‐phenyl)‐1,5,7a‐triphenyl‐tetrahydro‐imidazo[1,5‐b][1,2,4]oxadiazol‐2‐one

Abstract

The cis stereochemistry of 6‐(4‐methoxy‐phenyl)‐1,5,7a‐triphenyl‐tetrahydro‐imidazo[1,5‐b][1,2,4]oxadiazol‐2‐one was studied by use of a PM3 semi‐empirical quantum mechanical model, and x‐ray crystallographic analysis. It crystallizes in the monoclinic space group P2 ₁ /n with a = 10.812(1) Å, b = 16.464(2) Å, c = 13.379(1) Å, α = 90.00°, β = 98.39(1)°, γ = 90.00°, V = 2356.07(4) Å³, Z = 4, D _calc = 1.3067 g cm^?3, F(0 0 0) = 976.41, and μ = 0.086 mm^?1. The structure was solved by direct methods and refined to R = 0.066 for 1257 independent reflections [I > 4σ (I)]. The results from x‐ray diffraction were seen to be generally consistent with the results from previously reported spectroscopic investigations, beside theoretical calculations, except for conformations of five‐membered fused heterocycles. Two inter‐ and intramolecular weak interactions in addition to carbon atoms (C1 and C3) with different chiralities were found in the structure. The conformational study was performed by randomly scanning the potential energy surface belonging to the title compound with respect to selected torsion angles.     

Crystal Structures of Tetrakis‐(4‐chlorophenylthio)‐butatriene and Tetrakis‐(tert‐butylthio)‐butatriene

Tetrakis‐(4‐chlorophenylthio)‐butatriene (3a) and tetrakis‐(tert‐butylthio)‐butatriene (3b) were synthesized, and their crystal structures were determined. The compound 3a is monoclinic, space group P2₁/c, a=6.9785(8), b=8.6803(9), c=22.884(2) Å, β=93.887(6)^o, V=1383.0(3) ų, Z=2. The compound 3b is monoclinic, space group P2₁/n, a=11.0615(6), b=10.8507(4), c=11.2717(6) Å, β =116.427(2)^o, V=1211.5(1) ų, Z=4. The title compounds 3a and 3b reside on an inversion center so that only half of the molecule is crystallographically unique. Both compounds are not planar. The crystal structures of 3a and 3b have cumulated double bonds. The C7–C8–C8ⁱ and C5–C6–C6ⁱ angles that show the linearity in both structures, respectively, are 176.4(3)° in 3a and 175.6(2)° in 3b.     

Vacuum‐UV‐Radiation‐Induced Structural‐Functional Changes in Serum Albumin Molecules

Using the methods of spectrophotometry, luminescent analysis, and fluorescent probes, we have investigated the structural changes in bull serum albumin (BSA) molecules induced by the action of vacuum UV (VUV) radiation ( = 131161 nm, dose — 6300 kJ/m²). It has been found that the change in the spectralfluorescent properties of BSA molecules after irradiation under the conditions of different microsurroundings is caused by the unrolling of the protein globule due to the weakening and rupture of weak intramolecular bonds as well as by the photomodification of the aromatic amino acid residues in the composition of the protein macromolecule. A scheme of the phototransformation processes in the BSA molecules under the action of vacuum ultraviolet has been drawn. In accordance with this scheme the VUV light in the region of absorption of peptide bonds of protein molecules induces a disturbance in their thirdorder structure, which leads to a modification of the state of aromatic amino acid residues and a change in the functional properties of protein macromolecules.     

Intramolecular Hydrogen Bond in Steroid 5‐Hydroxy‐6‐Ketones and 5‐Hydroxy‐6‐Ketoximes of the Stigmastane Series

The intramolecular hydrogen bond in steroid 5hydroxy6ketones and 5hydroxy6ketoximes of the stigmastane series has been investigated by the method of IR spectroscopy. It is shown that 5hydroxy groups in cisA/Bsteroids are linked by the intramolecular hydrogen bond with polar substituents at C₃ and C₆. These hydrogen bonds are lacking in corresponding transA/Bsteroids. According to the IR spectra, intramolecular associates of polymer type are formed in 5hydroxy6hydroxyminosteroids.     

Spectral‐Luminescence and Generation Properties of 1‐Aza‐2‐Methyl‐6‐Aminopyrene and of Its Protolytic Forms

Spectral manifestations of protolytic forms of 1aza2methyl6aminopyrene in ethanol and aqueous solutions are investigated. The ionization constants of the protolytic forms are determined. The generation properties and photostability of a neutral molecule and a cation in excitation by an excimer XeCl laser are studied.     

Polystyrene‐b‐Poly(Ethylene‐r‐butylene)‐b‐Polystyrene Triblock Copolymer/Organoclay Nanocomposites and Their Phase Characteristics

Abstract

Intercalated polymer/clay nanocomposites were prepared using a polystyrene‐b‐poly(ethylene‐r‐butylene)‐b‐polystyrene (SEBS) cylindrical triblock copolymer. Dynamic rheological measurements, x‐ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetry analysis (TGA) were conducted to investigate the internal structure and physical and phase characteristics of the nanocomposites. The XRD data confirmed that the interlayer distance between the anisotropic silicates increased due to the intercalation of SEBS into the clay interlayers. As the clay loading increased, the onset points of the order–disorder transition (ODT) and order–order transition (OOT) were found to decrease, whereas the thermal decomposition temperatures, monitored by TGA, increased with the clay loading.     

Molecular and Crystalline Structure of 6,6'‐Dimethyl‐2,3,4,5,6,7‐Hexahydrobenzo[b]Furan‐3,4‐Dione

Different intermolecular compounds of 6,6'dimethyl2,3,4,5,6,7hexahydrobenzo[b]furan3,4dione have been investigated by IR spectroscopy and xray structural analysis methods. The relation between changes in the characteristic absorption bands of CH₂, CH₃, C=O, and C—O—C groups and the properties of the medium surrounding the molecule is established. Crystals of monoclinic syngony, of space group P2₁/n, are formed from a chloroformhexane mixture in crystallization. In the crystalline structure, shortened intermolecular contacts between the atoms of hydrogen of the CH₃ and CH₂ groups of cyclohexane cycles and the oxygen atom of the furan cycle, and also between the atoms of hydrogen of the CH₂ and CH₃ groups of both cycles and the oxygen of the cyclohexane cycle are revealed.     

Theoretical and Experimental Study of the Conformation and Vibrational Frequencies of N‐Acetyl‐L‐alanine and N‐Acetyl‐L‐alaninate

The vibrational frequencies of N‐acetyl‐L‐alanine (NAAL), its potassium salt (NAALK) and its free anionic form (NAAL^?) are calculated using density functional theory (B3LYP) combined with the 6‐311 + + G(d,p) basis set. The experimental Raman spectrum of solid NAALK and the scaling factors for calculated values are discussed as well. The three species are characterized by intramolecular NH…O hydrogen bonds leading to the formation of a five‐membered ring. As indicated by the intramolecular (N)H…O distances and by the ν(NH) frequencies, the strength of the intramolecular hydrogen bond is ordered as follows: NAAL^? < NAALK < NAAL^?. Owing to their difference in the coupling with other vibrational modes, the in‐plane and out‐of‐plane vibrations do not reflect the strength of the hydrogen bond.     

Spectral‐Luminescent Properties of 1,1‐Dioctadecyl‐3,3,3'3'‐Tetramethylindodicarbocyanineperchlorate in Binary Solutions

On the basis of investigation of the absorption and luminescence spectra of 1,1dioctadecyl3,3,3'3'tetramethylindodicarbocyanineperchlorate (D307) molecules and their nonamphiphilic analog in binary solutions of dimethylformamide and water of different composition, a mechanism underlying the quenching luminescence of the D307 molecules has been established which is related to the formation of nonluminescent associates. It is shown that the formation of the micelles of sodium dodecylsulfate (SDS) in a binary solution with 99% content of water destroys the associates, the D307 molecules are captured by the micelles, and their mobility in the micelles is limited.     

Rheological Behavior of Polyarylsulfone 1‐Butyl‐3‐Methylimidazolium Chloride Solutions

Polyarylsufone polymers are engineering thermoplastics that can only be dissolved in polar solvents. We found that polyarylsufone has good solubility in ionic liquid (IL) with IL being a new kind of green solvent; thus, ILs are potential substitutes for conventional molecular solvents. However, the thermodynamics in ionic liquids are different then those in conventional solvents, so ILs as solvents have attracted enormous attention recently. Rheological behavior is an important factor in polymer material processing. The rheological behavior of polyarylsulfone (PASF) in both N, N,‐dimethylacetamide (DMAc) and ionic liquid 1‐butyl‐3‐methylimidazolium chloride [(Bmim) Cl] were studied in this paper as a function of concentration for concentrated solutions. It is interesting that the rheological behavior of the PASF/(Bmim) Cl solution is very different from that of PASF/DMAc solutions. In DMAc, as concentration increases viscosity increases, while the rheological behavior of the PASF/(Bmim) Cl solution exhibits a maximum in the viscosity‐concentration plots.     

Steady‐State and Time‐Resolved Emission Studies of 6‐Methoxy Quinoline

Abstract

Steady‐state absorption, fluorescence excitation, and emission spectra of 6‐methoxy quinoline (6‐MQ) were measured at room temperature in cyclohexane, dioxane, ethanol, acetonitrile, water, and water–dioxane solvents. Absorption spectra of cyclohexane, n‐hexane, and isopentane solutions show resolved vibronic structure at room temperature. However, the excitation spectrum of cyclohexane solution is structureless and is found to be emission wavelength dependent, indicating the formation of at least two distinct species in the ground state. Similar behavior was observed in dioxane and water–dioxane solutions. For all other solutions, the fluorescence excitation spectrum of 6‐MQ was found to be the same for different emissions. Emission of 6‐MQ in all solvents consisted of two bands with their maxima around 355 nm (I) and 430 nm (II), the actual positions and the relative intensities being dependent on the solvent used. The bands I and II were respectively attributed to normal and protonated/H‐bonded species of either ¹L_a or ¹L_b states or mixed (¹L_a/¹L_b) state of ππ* character. Fluorescence decay of this dye in all solvents monitored over each emission maximum showed biexponential behavior, and the analysis yielded two different lifetime components for each emission band. The short and long fluorescence decay components were respectively in the range of 0.30–3.00 ns and 18–20 ns. The observed emission characteristics coupled with the nature of the fluorescence polarization spectra and two different decay components for each emission suggest the existence of two different conformers having two different excited electronic states.     

Structural Assignments of 1‐(β‐d‐Glucopyranosyl)‐1,2,3‐triazoles by 1H‐ and 13C‐NMR Study

The ¹H‐ and ¹³C‐NMR spectra of 1‐β‐d‐glucopyranosyl‐1,2,3‐triazole‐4,5‐dimethyl carboxylate, 1‐β‐d‐glucopyranosyl‐1,2,3‐triazole‐4,5‐dicarboxamide, ‐dialkylcarboxamide‐N‐nucleosides 4–18, and 6‐amino‐4H‐1‐(1‐β‐d‐glucopyranosyl)‐8‐hydroxy‐1,2,3‐triazolo[4,5‐e][1,3]‐diazepin‐4‐one 19 had been studied. Resonance signals and anomeric configurations were assigned by homo‐ and heteronuclear two dimensional methods (DQF‐COSY, HSQC, HMBC, HMQC, ROESY).     

Multilayer mirror fluorescence detection system for photon‐in photon‐out in‐situ carbon k‐edge NEXAFS

The Second International Workshop on Imaging Techniques with Synchrotron Radiation (ITSR) was held November 6–10, 2009, at the beautiful beach resort city of Sanya on the tropical island of Hainan province in the south of China, and followed on from a similar successful meeting in Hefei in December 2008. The meeting was supported by the National Natural Science Foundation of China, National Synchrotron Radiation Laboratory (NSRL) in Hefei, Institute of High Energy Physics (IHEP) in Beijing, INFN, Xradia Inc., and the Italian Ministry of Foreign Affairs based on an agreement for bilateral collaboration. This enthusiasm for collaboration is a reflection of the increasing interest in synchrotron-based research, particularly in the area of imaging and microscopy, which has been stimulated by the successful commissioning of various projects in China, such as the new Shanghai synchrotron light source and the upgrade of the Hefei synchrotron sources. Some further new projects are proposed that will focus even more on advancing the imaging capability in China and its application in different domains of science and technology. The Sanya meeting was therefore held at an important time and designed to bring world experts together to help build the user community, foster new scientific applications, and nurture young scientists. It is encouraging to witness that more than 10 students participated in the meeting, which included 25 oral presentations contributed by 40 delegates from 8 countries including China, Australia, the U.S., France, Germany, Italy, Japan, and the Netherlands.     

Isotope Effects by Comparing 1H‐ and 2D‐NMR Spectra of 9,9′‐Bisbicyclo[4.3.0]‐cyclonona‐2,4,7‐triene

Abstract

Inverse secondary kinetic isotope effects are determined for the dimerization of all‐cis‐cyclononatetraenyl radical, 1, to its corresponding dimer, all‐cis‐9,9′‐bicyclonona‐1,3,5,7‐tetraene, 2, (step 1, k _H/k _D=0.5), and cyclization of the latter to 9,9′‐bisbicyclo[4.3.0]cyclonona‐2,4,7‐triene, 3 (step 2, k _H/k _D=0.75). These results are obtained by comparison of ¹H‐ and ²D‐NMR spectra of 3 and employment of a simple statistical method for acquiring kinetic data. This new strategy appears superior to conventional methods in being fast, simple, and less expensive.     

Thermal Behavior of an Fe(III)‐2,9,16,23‐Tetramidephthalocyanine‐Grafted Poly(N‐Vinylcarbazole)

Abstract

The introduction of 2,9,16,23‐tetramide‐Fe(III)phthalocyanine [Fe(III)taPc] units into phosphorylated poly(N‐vinylcarbazole) yields an amorphous grafted polymer containing free carbazolyl groups, phosphonic acid attached to carbazolyl groups, and grafted Fe(III)taPc units as evidenced by infrared spectroscopy. Several thermal transitions were detected by differential scanning calorimetry (DSC). The thermodegradation of the grafted sample, analyzed by simultaneous thermogravimetry‐differential thermal analysis (TG‐DTA), showed successive endo‐ and exothermal reactions resulting from the development of a cross‐linked structure. To determine kinetic parameters, both isothermal and dynamic experiments were performed at the different steps of the degradation process and theoretical methods were applied.     

Resonant Raman Scattering Spectra of Zn‐Phthalocyanine and Zn‐Phthalocyanine‐d 16

We obtained the resonant Raman scattering spectra of Znphthalocyanine and of its fully deuterated analog, Znphthalocyanined ₁₆. We performed calculation of normal vibrations and using it, interpreted the Raman scattering spectra. We characterized the form of vibration with the aid of potential energy distribution. For the majority of vibrations the calculation adequately describes the observed isotropic shifts. The correspondence between the vibrational states of Znphthalocyanine and metal complexes of tetrabenzoporphin has been established in confirmation of the proposed detailed interpretation of the spectra.     

Influence of N‐Substitution on Electron Spin Resonance (ESR) Behavior of 2‐(2‐Nitrophenyl)‐1H‐benzimidazole Derivatives

Abstract

The synthesis of 2‐(2‐nitrophenyl)‐1H‐benzimidazole (1), 1‐benzoyl‐2‐(2‐nitrophenyl)‐1H ‐benzimidazole (2), and 1‐acetyl‐2‐(2‐nitrophenyl)‐1H‐benzimidazole (3) is reported. Stable radical anions (1 ^·?, 2 ^·?, and 3 ^·?) were generated by chemical reduction in DMSO and studied by ESR spectroscopy. The interpretation of the ESR spectra was done by means of computational simulation process. Hyperfine coupling constants were assigned by comparison with related compounds, and on the basis of calculation based on SCF INDO MO method in the unrestricted Hartree–Fock scheme.     

Poly(m‐Phenylene Isophthalamide) Ultrafine Fibers from an Ionic Liquid Solution by Dry‐Jet‐Wet‐Electrospinning

Ultrafine poly(m‐phenylene isophthalamide) (PMIA) fibers from PMIA solution in an ionic liquid via dry‐jet‐wet electrospinning technology are described. The morphology of the fibers with and without treatment in a coagulation water bath in the dry‐jet‐wet‐electrosinning process was observed by scanning electrical microscopy (SEM) and a high resolution optical microscope. The crystal structure of the fibers was analyzed by wide angle X‐ray diffraction (WAXD). The differences of morphologies and properties between the ultrafine fibers obtained by the electrospinning process and fibers from conventional wet‐spinning technology are discussed. The thermal properties of the ultrafine PMIA fibers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

Crystallization Behavior of PEO in Nano‐Structured PEO‐b‐PS/PPO Blends

Blends of poly (ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) diblock copolymer and poly (2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) homopolymer were obtained by solution blending, and the morphologies of PEO dispersed nanoparticles in PPO/PS matrix were observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The isothermal crystallization kinetics was studied using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Nonisothermal crystallization kinetics was studied using DSC. The results showed that PEO segments were easier to crystallize in the blend than in the copolymer probably due to the interfaces of PPO acting as nucleation sites to promote the crystallization of PEO. The crystallization of PEO blocks destroyed the pre‐existing microdomain structure even though the glass transition temperature of the matrix was much higher than the crystallization temperature.