The prototropic exchange equilibria of two drugs, nizatidine (I) and ranitidine(II), and also of structurally related the N,N'-dimethyl-2-nitro-1,1-ethenediamine molecule (III) were investigated. From the changes in electronic spectra in media of various acidity several protonation constants were determined. For pK values were -0.82, 1.95, and 6.67; for ranitidine pK values were 1.95 and 8.13; ...

A recently reported protolytic gating effect on the ring closing reaction of an oligo(phenylene ethynylene) (OPE) embedded difurylperfluorocyclopentene (S) with a dimethylaminophenyl chain link in each of the side arms, was quantitatively analyzed in detail. The reaction system (So, SoH(+), SoH2(2+), Sc, ScH(+), ScH2(2+)) comprising three protolytic forms in both open and closed configuration, ...

The surface properties of poly(methyl methacryl-ate-co-n-butyl methacrylate-co-cyclopentyl methacryloxy propyl-polyhedral oligomeric silsesquioxane) (poly(MMA-co -BMA-co-POSSMA)) were studied by means of inverse gas chromatography (IGC) using 10 non-polar and polar solvents as the probes. Thermodynamic parameters of adsorption, such as the dispersive component of the surface energy, the specifi...

The role of pyridinium cations in electrochemistry has been believed known for decades, and their radical forms have been proposed as key intermediates in modern photoelectrocatalytic CO(2) reduction processes. Using first-principles density functional theory and continuum solvation models, we have calculated acidity constants for pyridinium cations and their corresponding pyridinyl radicals, a...

A 1H NMR study of urocanic acid dissolved in water/dimethyl sulfoxide mixtures together with potentiometric determinations of its two successive acidities in the same solutions reveal that a proton is transferred from the imidazolium ring to the carboxylate group when the amount of dimethyl sulfoxide is increased. An analysis of the potentiometric data by means of the classical Hammett linear r...

The hyperspectral imaging technology is used to detect early-maturing pear’s effective acidity nondestructively, and effective prediction model is established. 145 pears’ hyperspectral images are obtained in the wavelength range of 400nm-1000nm. Total 145 pears are separated into the calibration set (77 samples) and prediction set (68 samples). Early-maturing pear’s effective acidity partial le...