Franco Andreani

Ester-functionalized poly(3-alkylthienylene)s: substituent effects on the polymerization with FeCl3

Abstract Ester-functionalized poly(3-alkylthienylene)s were obtained by chemical oxidation with FeCl3. Substituents with both different total length and different distance of the ester group from the thiophene ring were examined. The main reaction solvent studied was chloroform which gave polymers with high molecular weight and incomplete conversion of the monomer. Some polymers were synthesized with a new procedure involving the precipitation of FeCl3 from a saturated nitromethane solution by a tetrachloride solution of the monomer. In this way, lower molecular weights and complete monomer conversion were obtained. The effect of different substituent groups on the polymer microstructure was examined using 1H NMR spectroscopy. With both polymerization procedures, the regioregularity and absorption maximum in the visible spectrum increase with increasing length of the oligomethylenic spacer between thiophene ring and ester group.

Immobilization of α-l-arabinofuranosidase on chitin and chitosan

Abstract The present research is mainly concerned with the immobilization of α- l -arabinofuranosidase (EC 3.2.1.55) from Aspergillus niger , for use in the food processing industry and in particular in oenology. This enzyme was immobilized on chitosan by means of covalent coupling to a glutaraldehyde pretreated support ( functionalization ), adsorption on the support and crosslinking with glutaraldehyde, which was added either in the absence ( crosslinking ) or presence ( conjugation ) of the enzyme solution. Conjugation proved to be the better method as it ensured good biocatalyst activity (about 150 U/g) but, above all, good stability, better than that reported for the free enzyme.

Synthesis of imidazo[2,1-b]thiazoles as herbicides

Abstract A series of imidazo[2,1-b]thiazoles bearing halogens or a sulfonylurea group or an imidazolidone group, were synthesized and subjected to pre- and post-emergence herbicidal tests. 5-Bromo-6-(3-pyridyl)-2,3-dihydroimidazo[2,1-b]thiazole (4e) and 6-(2,3,4-trichlorophenyl)-2,3-dihydroimidazo[2,1-b]thiazole-5-carboxylic acid (8b) showed moderate activity in the post-emergence herbicidal tests only.

Immobilization of the glycosidases: α-l-arabinofuranosidase and β-d-glucopyranosidase from Aspergillus niger on a chitosan derivative to increase the aroma of wine. Part II

Abstract The purpose of this paper was to study the immobilization of two glycosidases, α- l -arabinofuranosidase (EC 3.2.1.55) and β- d -glucopyranosidase (EC 3.2.1.21), contained in a commercial preparation and purified as reported in Part I. The procedure which proved to be the best is simple and inexpensive to perform, employing the chitosan derivative, glyceryl-chitosan, especially synthesized and characterized, as a support. The glycosidases were adsorbed on this support and cross-linked with glutaraldehyde to prevent them from being released into the wine. Subsequent reduction of the biocatalyst with sodium borohydride allowed for improved stability. Finally, the immobilized glycosidases were compared with free ones in terms of optimum pH and temperature, stability over time, and kinetics parameters (Km and Vmax) after which they were employed for aromatizing a model wine solution containing aromatic precursors.

Electrochemical impedance spectroscopy of polyalkylterthiophenes

The Electrochemical Impedance Spectroscopy investigation of two isomer polyalkylterthiophenes, namely poly-3′4′- and 33″-didodecylterthiophene was carried out at different stages of polymers oxidation. In the potential range 0.4⩽E⩽0.7 V vs Ag/AgNO3 the ionic resistance Rion associated with the insertion in the polymer structure of the doping species PF−6 V, decreases for poly-33″-didodecylterthiophene with increasing potential whereas the onset of a blocking process occurs when E>0.7 V vs Ag/AgNO3. Such results were compared with the corresponding in-situ variations of the conductivity at different stages of poly-33″-didodecylterthiophene oxidation. The Electrochemical Impedance Spectroscopy characterization of the isomer poly-3′4′-didodecylterthiophene could not be fully accomplished because of the scarce wettability of this system in the electrolyte solvent.

Potential anti-tumor agents XVI. Imidazo[2,1-b]thiazoles

Abstract A number of imidazo[2,1-b]thiazoles have been synthesized and tested in mice bearing Ehrlich ascites tumor cells. The nitrogen mustard 5 had a T C of 140 at 8 mg/kg.

Synthesis and polymerization of 3,3″-di[(S)-(+)-2-methylbutyl]-2,2′:5′,2″-terthiophene: a new monomer precursor to chiral regioregular poly(thiophene)

3,3″-Di[(S)-(+)-2-methylbutyl]-2,2′:5′,2″-terthiophene, having two equivalent reactive positions, allows the synthesis of the corresponding optically active poly(thiophene) with regioregular enchainment by using an aspecific oxidative polymerization method.

Novel poly(3,3″ - and 3′, 4′-dialkyl-2, 2′:5′, 2″- terthiophene)s by chemical oxidative synthesis: evidence for a new step towards the optimization of this process

Abstract The synthesis of poly(3, 3″- and 3′, 4′-dialkyl-2, 2′:5′, 2″-terthiophene)s possessing a full ordered regiochemistry of bonding and substitution, as well as a conjugated chain with the minimum possible amount of steric interactions between the substituents, is described. The synthesis was achieved through the simplest chemical method, namely the oxidative polymerization reaction based on FeCl 3 as oxidant. The structural regularities of the polymers have been confirmed by Fourier transform infra-red ( FT i.r.) and 1 H nuclear magnetic resonance (n.m.r.) spectroscopy. Experimental conditions of special interest for improving the yields and molecular weights of the neutral soluble polymers are discussed.

First approach to ester-functionalized poly(3-alkylthienylene)s

SummaryThe monomer 2-(3-thienyl)ethylene hexanoate can be chemically polymerized and copolymerized with an equimolar amount of 2-(3-thienyl)ethanol to afford the two first examples of soluble ester-functionalized poly(3-alkylthienylene)s. The undoped polymers are readily processable into uniform films by solution-casting.

Synthesis and characterization of neutral newly substituted polyalkylthiophenes

Abstract In this work, two newly substituted polyalkylthiophenes, poly(3,4-dihexyl-2,2′-bithiophene) and its didodecyl analogue have been prepared in order to compare their properties with those of the regioisomeric poly(3-alkylthiophene)s containing the same amount of head-to-tail configuration (conventional PATs). Remarkable differences between the material characteristics of these two kinds of polyalkylthiophene have been observed, thus enabling us to elucidate the side chains effects exclusively attributable to the difference between the side chains distribution along the polythiophene backbone. In the neutral bulk state, compared to that of the conventional PATs, the polymers prepared for this study have been found more thermostable materials exhibiting higher flexibility and less ordered (in the crystallographic sense) molecular assemblies, still able to afford an average conjugation length as long as that of the conventional PATs, but varying between wider limits. This seems to be closely connected with a lower degree of side chains interactions and/or the high proportion (50%) of unsubstituted thiophene rings. Based on these effects of molecular structure on the material properties at room temperature, we have anticipated in the novel polymers, at higher temperatures, the possibility of weaker thermochromism and better conductivity stability than in their regioisomeric conventional PATs.