Revisiting the influence of pH on J and chemical shifts of glycine and alanine short oligopeptides.

The pH dependence of several NMR parameters of glycine and alanine short oligopeptides has been reported previously in different studies. Here we have thoroughly examined, summarized and demonstrated the dependences of H, C and N chemical shifts and protonation states of amino acids using two-dimensional NMR experiments. Nevertheless, J one bond spin-spin coupling constants are more informative and convenient for determination of the position and protonation state of glycine and alanine residue in the oligopeptide chain.

Long range deuterium isotope effects on C NMR chemical shifts of 2-alkanones in CDOD solutions of imidazolium acetate ionic liquids.

Deuterium isotope substitution in one part of a molecule could produce a significant effect on chemical shifts of neighbouring nuclei as well as on nuclei, located far from the site of replacement. To estimate how far this influence could extend the reaction of proton-deuterium exchange of several 2-alkanones in deuterated methanol solutions of 1-methyl 3-ethyl imidazolium acetate ionic liquid (IL) was studied in detail using C NMR spectroscopy. Deuteration occurs in alkyl groups of 2-alkanones neighboring the ketonic group keto-enol tautomerization catalyzed by IL.

Proton-deuterium exchange of acetone catalyzed in imidazolium-based ionic liquid-DO mixtures.

The reaction of the proton-deuterium exchange of acetone in imidazolium-based ionic liquid (IL)-deuterium oxide mixtures was studied in detail NMR spectroscopy. Certain ILs exhibit considerable catalytic properties and contribute to the course of reaction up to the complete deuteration. The efficiency of deuterium exchange crucially depends on the features of ILs; the type of anion and chain length of cation.

Designing amphotropic smectic liquid crystals based on phosphonium salts for partial ordering of solutes as monitored by NMR spectroscopy.

The ordering parameters of selected solutes from NMR spectroscopic measurements have been assessed in the thermotropic and amphotropic smectic liquid-crystalline phases of a wide structural range of phosphonium salts with three equivalent long n-alkyl chains, one shorter chain, and various anions. The nature of the added liquids that convert the salts to amphotropic phasesalcohols and other small organic moleculesand their concentrations have been determined. These factors are correlated with the NMR-derived parameters in order to understand how the phases can be optimized to maximize information about the solutes.

Room-temperature and low-ordered, amphotropic-lyotropic ionic liquid crystal phases induced by alcohols in phosphonium halides.

Tri- n-decylmethylphosphonium chloride and bromide ( 1P10X) salts are not liquid crystalline. However, mesophases are induced by adding very small amounts of an alcohol or water. The temperature ranges of the induced smectic A 2 (SmA 2) liquid-crystalline phases can be very broad and the onset temperatures can be below room temperature depending upon the concentration of the alcohol or water and the structure of the alcohol.