Organic solid photochromism by photoreduction mechanism: Polar aprotic viologen copolymers

Copolymers of vinyl viologens such as N-vinylbenzyl-N′-yalkyl and N-(γ-methyacryloyloxy)propyl-N′-propyl-4,4′-bipyridinium dihalides and polar aprotic comonomers such as N-vinyl-2-pyrrolidone (VP) and N,N-dimethylacrylamide (DMA) were prepared by the copolymerizations of vinyl viologens with DMA and the chemical modifications of VP copolymers containing reactive halogens. Copolymers containing various viologen anions such as Br^?, BF, SO, and I^? were also prepared by the anion exchange of copolymers containing Cl^?. The photocolor developments of these aprotic copolymers in the film state were completely reversible and faster than for the corresponding copolymers with protic comonomers such as acrylamide and 2-hydroxyethyl acrylate, all with characteristic absorption spectra attributable to single radical cations.     

Syntheses of N-substituted carbazoles involving polymerizable terminal vinyl groups

Eleven N-substituted carbazoles (CZ) with terminal vinyl groups were synthesized by five sequences of reaction: N-(p-vinylbenzyl)- and N-β-(vinyloxyethyl)CZ by N-alkylations of potassium CZ with corresponding chlorides; N-(β-acryloyloxyethyl)CZ by the esterification of N-(β-hydroxyethyl)CZ with acryloyl chloride; N-acrylamido-or methacryl-amido-methyl CZ from N-hydroxymethyl CZ and acryl- or methacrylamide; N-(3-acryloyl- or methacryloyl-oxy-2-hydroxypropyl)CZ and N-[3-(p- or m-vinylanilino)-2-hydroxypropyl] CZ from N-(2,3-epoxypropyl)CZ and acrylic or methacrylic acid and p- or m-vinylaniline, respectively; and 2-[β-(N-carbazyl)propionyloxy]ethyl acrylate or methacrylate by the Michael addition of CZ to 2-hydroxyethyl acrylate or methacrylate, followed by esterifications. The vinyl polymers with pendant carbazyl groups more or less distant from the polymer backbones, prepared by conventional radical or cationic polymerization procedures, indicated charge-transfer spectra with 2,4,7-trinitrofluorenone (TNF) in tetrahydrofuran (THF) solutions that are spread over most of the visible range.     

Chemical release control—Schiff bases of perfume aldehydes and aminostyrenes

Schiff bases of p- and m-aminostyrenes with perfume aldehydes such as citral, cinnamaldehyde, piperonal, vanillin, and ethyl vanillin were synthesized in ethanol in more than 50% yield. Water-soluble copolymers of these Schiff bases with N-vinyl-2-pyrrolidone or with N,N-dimethylacrylamide were obtained. The hydrolytic behavior of Schiff base monomers and copolymers to liberate perfume aldehydes was structure dependent, thereby affording chemical release control.     

Multivariate classification of cigarettes according to their elemental content determined by inductively coupled plasma optical emission spectrometry.

In this paper we describe our study on the characterization of cigarette samples according to their mineral content. Acid digestion assisted by microwaves was employed, and inductively coupled plasma optical emission spectrometry was the analytical technique used for the determination of Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P and Sr in conventional, light, and flavorized cigarettes. Multivariate techniques, such as hierarchical clusters analysis (HCA) and principal-component analysis (PCA), were applied to discriminate among different types of cigarettes. Cluster analysis and principal-component analysis showed differences in cigarettes according to the type and mineral composition. The cigarette samples were divided within the 3 groups according to their mineral composition. Ca, Sr, Cu, K and Na were the most important elements for cigarette classification, and only these 5 variables were sufficient for the classification and discrimination of the evaluated types of cigarettes.     

PICOSECOND TRANSIENT BEHAVIOR OF REACTION-CENTER PARTICLES OF PHOTOSYSTEM I ISOLATED FROM SPINACH CHLOROPLASTS. ENERGY AND ELECTRON TRANSFER UPON SINGLE AND MULTIPLE PHOTON EXCITATION

Abstract— Both [15-¹³C] and [14-¹³C] all-trans-retinals were synthesized. Bacteriorhodopsin containing [14-¹³C]retinal as a chromophore, when solubilized with octyl-β-D-glucoside, showed characteristic resonances at 125 and 118 ppm from tetramethyl silane. The former was assigned to the signal from free retinal and the latter from protonated Sehiff base. When the bacteriorhodopsin was denatured in sodium dodecyl sulfate, the signal at 118 ppm disappeared, while the signal at 125 ppm rather increased.
In the case of bacteriorhodopsin containing [15-¹³C]retinal, when solubilized with Triton X-100, a characteristic resonance at 169 ppm was distinguishable as a shoulder peak superimposed on the broad signal of carbonyl carbons and it was assigned to the signal from the protonated Sehiff base. The other signal observed at 191 ppm was from free retinal.
These results suggested that the Sehiff base of bacteriorhodopsin is protonated in the dark.     

4-Alkoxy-2-hydroxy-4′-vinylbenzophenones,ultraviolet-absorbing monomers

2,4-Dihydroxy-4′-vinylbenzophenone (I) and its 4-alkyl ethers (II), Me, Et, n-Bu, n-Oct, and n-dodecyl, were prepared in three steps by Hoesch synthesis, starting with p-(2-bromoethyl) benzonitrile and resorcinol and its monoalkyl ethers. I and its precursor 2,4-dihydroxy-4′-(2-bromoethyl) benzophenone were also converted into their 4-alkyl ethers with alkyl halides in dimethylformamide (DMF) in the presence of sodium hydrogen carbonate. Copolymerizations of I and II with styrene took place smoothly with satisfactory conversions to yield copolymers with ε-values around 10⁴ L/mol cm^?1 per benzophenone unit over the ultraviolet (UV) range of 235–340nm.     

Purification of serine hydroxymethyltransferase from Bacillus stearothermophilus with ion-exchange high-performance liquid chromatography.

The gene of serine hydroxymethyltransferase (SHMT) of a thermophilic bacterium Bacillus stearothermophilus was expressed in Escherichia coli, and SHMT was successfully purified from the crude extract of E. coli in two steps while maintaining the enzymatic activity. The purification steps involved ammonium sulphate precipitation followed by high-performance liquid chromatographic separation using the anion-exchange column Fractogel EMD DEAE-650(S). In addition to the DEAE column, three other types of anion- and cation-exchange columns were also studied for their ability to separate SHMT, and the performance of the four columns were compared.