The paper presents results of the studies on photochemical stability of naproxen (NAP) and niflumic acid (NIF) in their liquid inclusion complexes with β-cyclodextrin (β-CD). The process of photodegradation was studied by UV spectrophotometry. Quantitative evaluation of the photochemical decomposition was performed on the basis of the calculated rate constant, k0, for the pure drug, k, the photodegradation rate constant of the drug in the inclusion

The inclusion of vanillin by beta-cyclodextrin was investigated by 1H NMR. The continuous variation technique was used to evidence the formation of soluble 1:1 complex in aqueous solution. The association constant of vanillin with beta-cyclodextrin has been obtained at 298 K by fitting the experimental Delta_delta_obs = delta_free - delta_obs of the observed guest and host protons, with a non-linear regression method. Besides the effective association

The major protein component from aleurone cells of barley (Hordeum vulgare L.), PACB, is related to 7S globulins present in other cereals and to the vicilin-type 7S globulins of legumes and cotton seed. It contains 4 subunits of about 20, 25, 40 and 50 kDa molecular weights. The N-terminal sequence of 16 amino acids (over 260 atoms) in the protein was previously determined, and our aim is the prediction of its secondary structure. The empirical Chou-Fasman

A self-association of vanillin have been studied by 1H NMR spectroscopy using the analysis of proton chemical shifts changes in aqueous solution as a function of concentration. The experimental results have been analysed using indefinite non-cooperative and cooperative models of molecular self-association, enabling the determination of equilibrium constants, parameters of cooperativity and the limiting values of vanillin proton chemical shifts in

2-(2',4'-Dinitrobenzyl)-pyridine is a photochromic molecule presenting a proton transfer reaction from the methylene group to the nitrogen of the pyridine, both in solution and in the crystalline state. Its photochromism in solution depend on the solvent characteristics as: his polarity, his protic character (tendency of liberating a proton), or on his hydroxylic properties (aptitude of creating hydrogen bonds solute-solvent). In this report, the

We report a reversible liquid–solid transition upon heating of a simple solution composed of a-cyclodextrine (alpha-CD), water, and 4-methylpyridine. These solutions are homogeneous and transparent at ambient temperature and solidify when heated to temperatures between 45° and 75°. Quasielastic and elastic neutron scattering show that molecular motions are slowed down in the solid and that crystalline order is established. The solution "freezes

When working in the field of host-guest supramolecular chemistry in order to quantitatively appreciate the complex formation, the association constants have to be determined. For this purpose, in this contribution, a non-linear least square curve-fitting program, ConstEq, developed in our group, is presented.

Ab initio density functional calculations were performed on the CH2 pale yellow stable tautomer of 2-(2',4'-dinitrobenzyl)pyridine and on his photoinduced dark blue NH tautomer. We used B3LYP hybrid functional with 6-31G(d), 6-31G** and 6-31++G** basis sets. Good agreement is found between the calculated and experimental structures and vibrational spectra. The discrepancies are associated with the fact that the experimental values are obtained from

Novel extended tetrahedral forms of CO2 have been synthesized recently under high-pressure conditions. We perform ab initio density functional theory calculations to investigate whether doping with Si can extend the stability range of such tetrahedral forms of CO2 to ambient pressure. Calculations are performed with a simple cubic cell containing eight formula units in a beta-cristobalite-like structure. Though we find that all the SixC1-xO2 structures

The interaction between indomethacin and human serum albumin (HSA) was investigated by fluorescence quenching technique and UV–vis absorption spectroscopy. The results of fluorescence titration revealed that indomethacin, strongly quench the intrinsic fluorescence of HSA by static quenching and nonradiative energy transfer. The binding site number n and the apparent binding constant KA, were calculated using linear and nonlinear fit to the experimental