Tetrahydrofuran

About: Tetrahydrofuran is a research topic. Over the lifetime, 11778 publications have been published within this topic receiving 158241 citations. The topic is also known as: diethylene oxide & 1,4-epoxybutane.

Chlorophyll a self-assembly in polar solvent-water mixtures.

Abstract: The conversion of chlorophyll a (Chl a) monomers into large aggregates in six polar solvents upon addition of water has been studied by means of absorption, fluorescence spectroscopy and fluorescence lifetime measurements for the purpose of elucidating the various environmental factors promoting Chl a self-assembly and determining the type of its organization. Two empirical solvent parameter scales were used for quantitative characterization of the different solvation properties of the solvents and their mixtures with water. The mole fractions of water f1/2 giving rise to the midpoint values of the relative fluorescence quantum yield were determined for each solvent, and then various solvent-water mixture parameters for the f1/2 values were compared. On the basis of their comparison, it is concluded that the hydrogen-bonding ability and the dipole-dipole interactions (function of the dielectric constant) of the solvent-water mixtures are those that promote Chl a self-assembly. The influence of the different nature of the non-aqueous solvents on the Chl aggregation is manifested by both the different water contents required to induce Chl monomer-->aggregate transition and the formation of two types of aggregates at the completion of the transition: species absorbing at 740-760 nm (in methanol, ethanol, acetonitrile, acetone) and at 667-670 nm (in pyridine and tetrahydrofuran). It is concluded that the type of Chl organization depends on the coordination ability and the polarizability (function of the index of refraction) of the organic solvent. The ordering of the solvents with respect to the f1/2 values--methanol < ethanol < acetonitrile < acetone < pyridine < tetrahydrofuran--yielded a typical lyotropic (Hofmeister) series. On the basis of this solvent ordering and the disparate effects of the two groups of solvents on the Chl a aggregate organization, it is pointed out that the mechanism of Chl a self-assembly in aqueous media can be considered a manifestation of the Hofmeister effect, as displayed in the lipid-phase behavior (Koynova et al., Eur. J. Biophys. 25, 261-274, 1997). It relates to the solvent ability to modify the bulk structure and to distribute unevenly between the Chl-water interface and bulk liquid.

Highly Luminescent Polymers Containing the 2,3,5,6-Tetraarylated Pyrrolo[3,4-c]pyrrole-1,4-dione (N-Aryl DPP) Chromophore in the Main Chain

Abstract: Synthesis and characteristic properties of polymers P-1−P-3 are described containing the 2,3,5,6-tetraarylated pyrrolo[3,4-c]pyrrole-1,4-dione unit in the main chain. P-1 is prepared from 2,5-bis(4-t-butylphenyl)-3,6-bis(4′-bromophenyl)pyrrolo[3,4-c]pyrrole-1,4-dione (DPP1) and 9,9-di-n-hexylfluorene-2,7′-bispinacolato-boronester 3, P-2 from 2,5-bis(4′-bromo-phenyl)-3,6-bis(4-t-butylphenyl)-pyrrolo[3,4-c]pyrrole-1,4-dione (DPP2) and 3, and P-3 from DPP1, 3, and 2,5-bis(n-hexyloxybenzene)-1,4-bispinacolatoboronester 4 via Pd-catalyzed Suzuki coupling. Molecular weights of the polymers are about 8000−10 000 Da. All polymers are soluble in common organic solvents such as toluene, chloroform, dichloromethane, tetrahydrofuran (THF), and dimethyl sulfoxide (DMSO) and exhibit a strong fluorescence with Stokes shift up to 56 nm (P-3) and quantum yield up to 81% (P-1). Although P-1 and P-2 are isomers, their optical and electrochemical properties are very different. P-1 with a polyconjugated carbon backbone exhibi...

Radical high polymerization of di-tert-butyl fumarate and novel synthesis of high molecular weight poly(fumaric acid) from its polymer

Abstract: Di-tert-butyl fumarate (DtBF) was found to homopolymerize easily with 1,1′-azobisisobutyronitrile and benzoyl peroxide as radical initiators at 50~80°C to give a nonflexible rod-like polymer, poly(tert-butoxycarbonylmethylene) with number-average molecular weight of more than 100,000. The colorless powderlike polymer thus obtained was soluble in benzene, toluene, carbon tetrachloride and tetrahydrofuran, and gave a transparent film or fiber from its toluene solution. This polymer did not melt, but it underwent degradation with a quantitative elimination of isobutene at 180~190°C. The remaining polymer was confirmed to be a pure poly(fumaric acid), poly(hydroxycarbonylmethylene). Therefore, the degradation of poly(DtBF) in solution at 180~190°C was found to be a new route for synthesizing of a high molecular weight poly(fumaric acid).