Unequal effect of ethanol-water on the stability of ct-DNA, poly[(dA-dT)]₂ and poly(rA)·poly(rU). Thermophysical properties.

Ethanol affects unequally the thermal stability of DNA and RNA. It stabilizes RNA, while destabilizing DNA. The variation of the relative viscosity (η/η0) of [poly(dA-dT)]2 with temperature unveils transitions close to the respective denaturation temperature, calculated spectrophotometrically and calorimetrically.

RNA triplex-to-duplex and duplex-to-triplex conversion induced by coralyne.

Spectrophotometric, circular dichroism, calorimetric, displacement assay and kinetic analyses of the binding of the fluorescent dye coralyne to poly(A)2poly(U) have served to enlighten the ability of the dye to produce dramatic changes in the RNA structure. The sets of data assembled convey that coralyne is able to induce the triplex-to-duplex conversion and also the duplex-to-triplex conversion according to a non-reversible cycle governed by temperature, provided that the [dye]/[polymer] ratio (CD/CP) is maintained constant above unity. Alternatively, at room temperature the triplex is formed at (roughly) CD/CP < 1 and the duplex at CD/CP > 1.

Microwave dielectric relaxation spectroscopy study of alkan-1-ol/alkylbenzoate binary solvents.

The structure and dynamics of alkan-1-ol/alkylbenzoate binary mixtures have been studied by microwave dielectric relaxation spectroscopy in the 200 MHz to 20 GHz frequency range. The binary mixtures of methanol, ethanol, propan-1-ol, butan-1-ol, and pentan-1-ol with methyl, ethyl, propyl, and butyl benzoates were studied at 298.15 K.

Heat capacity behavior and structure of alkan-1-ol/alkylbenzoate binary solvents.

Heat capacities for the binary mixtures of methanol with (C(1)-C(4)) alkylbenzoates and methylbenzoate with (C(1)-C(11)) alkan-1-ols have been measured over the whole composition range at 298.15 K under atmospheric pressure. From the experimental measurements, the derived excess molar heat capacities and partial excess molar heat capacities at infinite dilution have been calculated.

Preferential solvation in alkan-1-ol/alkylbenzoate binary mixtures by solvatochromic probes.

The binary mixtures of methanol with (C(1)-C(4)) alkylbenzoates and of (C(1), C(3), C(5), C(7), C(9), C(11)) alkan-1-ols with methylbenzoate were used as solvents to look into the preferential solvation and intermolecular interactions of the solvatochromic indicators 2-nitroanisole, 4-nitroaniline, 4-nitrophenol, and Reichardt's dye by UV-vis measurements. The experimental data at 298.15 K have served to deduce the corresponding Reichardt and Kamlet-Taft parameters of the mixed solvents.