Synthesis and electrochromic properties of a new family of methacrylate polymers containing pendant oligothiophenes

A new family of methacrylate polymers containing pendant terthiophene, quaterthiophene, quinquethiophene, and sexithiophene was synthesized by the radical polymerization of the corresponding methacrylate monomers, and the electrochemical and electrochromic properties were investigated. The anodic oxidation of these polymers in the presence of tetra‐n‐butylammonium perchlorate as a supporting electrolyte produced radical‐cation salts of pendant oligothiophenes with ClO as a dopant. The electrochemically oxidized polymers had partially crosslinked structures resulting from the coupling reaction of pendant oligothiophene radical cations, the extent of crosslinking significantly decreasing with the increasing conjugation length of the pendant oligothiophenes. Comparative spectroelectrochemical studies of the monomers in solution and the polymers as solid films showed that π‐dimer formation of oligothiophene radical cations took place more readily for the polymer films than for the monomers in solution. This new family of methacrylate polymers containing pendant oligothiophenes constitutes a new class of potential electrochromic materials, undergoing reversible, clear color changes on electrochemical oxidation and reduction. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2471–2484, 2003     

Screening of matrix suitable for immobilization of microbial cells

To find a suitable matrix for immobilization of microbial cells, synthetic and natural polymers were screened. As a result,kappa-carrageenan,iota-carrageenan, furcellaran, sodium alginate, ethyl succinylated cellulose, succinylated zein, and 2-methyl-5-vinyl-pyridine-methylacrylate-methacrylic acid copolymer were studied. These polymers were induced to gel under mild conditions.Streptomyces phaeochromogenes cells having glucose isomerase activity were successfully immobilized in these polymer matrices. If a gelinducing reagent were added to a substrate solution, these gel matrices could be stabilized. The microbial cells did not leak out from the gel lattice. When these immobilized cells were treated with hardening reagents such as glutaraldehyde or tannins, the gel matrices were strengthened, and the glucose isomerase activity became stable for a long period even in the absence of gel-inducing reagents. Among these polymer matrices tested,kappa -carrageenan was most suitable for immobilization of microbial cells.     

Enzymatic hydrolysis of alpha- and beta-oligo(L-aspartic acid)s by poly(aspartic acid) hydrolases-1 and 2 from Sphingomonas sp. KT-1

The enzymatic hydrolysis of alpha- and beta-oligo(L-aspartic acid)s by PAA hydrolase-1 and PAA hydrolase-2 (purified from Sphingomonas sp. KT-1) was performed to elucidate the mechanism of the microbial degradation by Sphingomonas sp. KT-1 of the thermally synthesized alpha,beta-poly(D,L-aspartic acid) (tPAA). GPC analysis of the hydrolyzed products of alpha- and beta-tetra(L-aspartic acid)s by PAA hydrolase-1 has showed that PAA hydrolase-1 is capable of hydrolyzing only the specific amide bonds between beta-aspartic acid units. The RP-HPLC analysis of the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s (4 and 5 mers) by PAA hydrolase-1 has suggested that the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s occurs via an endo-mode cleavage. In contrast, PAA hydrolase-2 hydrolyzed both alpha- and beta-oligo(L-aspartic acid)s via an exo-mode cleavage to yield L-aspartic acid as a final product. A kinetic study on the enzymatic hydrolysis of alpha-oligo(L-aspartic acid)s (3 to 7 mers) by PAA hydrolase-2 has indicated that Km values are almost independent of the number of monomer units in oligomers of 4 to 7 mers, while that Vmax values are markedly dependent on the chain length and show a maximum value at 5 mer.     

Use of literature values of temperature programmed retention indexes in qualitative analysis by isothermal gas chromatography

Numerous reports have appeared on the determination of temperature programmed retention indexes in gas chromatography and although chromatographic variables should be completely consistent with published data if such indexes are to be of use, the reproduction of such rigorous parameters is quite difficult. This report presents an approximate method for using published values of temperature programmed retention indexes in isothermal chromatography. In general, the temperature dependence of the isothermal retention indexes of a number of compounds can be expressed as a series of oblique lines on a plot with retention index as the abscissa and temperature as the ordinate; the elution order of the compounds at a given, isothermal, temperature is then indicated by the points at which the compounds' oblique lines cut the horizontal line corresponding to the temperature of interest. In linear temperature programmed chromatography, the horizontal line representing isothermal operation becomes, to a first approximation, a sloping line with a gradient corresponding to the programming rate: this has been verified experimentally and may be valid over a wide range of temperatures. This line can be used to predict isothermal retention indexes for use in qualitative analysis.     

Reaction of a diphosphene with various halogens

Bis(2,4,6-tri-$\text{tert}$-butylphenyl) diphosphene reacts with various halogens to give the corresponding phosphoric dihalides, haloarene, and arene depending upon the halogen and solvent used.     

Microwave spectrum and the structure of benzoyl chloride

The microwave spectrum of benzoyl chloride was observed in the frequency range 12–18.6 GHz. Rotational constants have been obtained for the ground vibrational state, the first three excited torsional states of the COCl group, and one of the out-of-plane bending states. The residual inertial defect obtained from the ground and the torsional excited states indicates that the equilibrium conformation is planar. Ab initio MO calculations (STO-3G) showed the potential energy curve as a function of the COCl torsional angle to be rather flat around zero degrees.