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.

Synthesis, Characterization, and Study of Catalytic Activity of Chiral Cu(II) and Ni(II) Salen Complexes in the α-Amino Acid C-α Alkylation Reaction.

A new family of Cu(II) and Ni(II) salen complexes was synthesized and fully characterized through various physicochemical methods. Their catalytic activity was evaluated in the phase transfer C-alkylation reaction of the Schiff bases of D,L-alanine ester and benzaldehyde derivatives. It was found that the introduction of a chlorine atom into the - and -positions of the phenyl ring of the substrate resulted in an increase in both the chemical yield and the asymmetric induction ( 66-98%).

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.