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1H and 13C NMR spectra of 2-acyl-substituted cyclohexane-1,3-diones (acyl = formyl, 1; 2-nitrobenzoyl, 2; 2-nitro-4-trifluoromethylbenzoyl, 3) and lithium sodium and potassium salts of 1 have been measured. The compound 3, known as NTBC, is a life-saving medicine applied in tyrosinemia type I. The optimum molecular structures of the investigated objects in(More)
A methodology enabling investigation of a multicomponent tautomeric and acid-base equilibria by (13)C NMR spectroscopy supported by theoretical calculations has been proposed. The effectiveness of this method has been illustrated in a study of 2-oxopurine, 6-oxopurine (hypoxanthine), 8-oxopurine, and 2,6-dioxopurine (xanthine) in neutral and alkaline(More)
Magnetic shielding and indirect spin-spin coupling phenomena are tensorial properties and both their isotropic and anisotropic parts do affect NMR spectra. The involved interaction tensors, σ and J, can nowadays be theoretically calculated, although the reliability of such methods in the case of anisotropic parameters, Δσ and ΔJ, in systems involving heavy(More)
Investigation of 15N NMR spectra of isotopically enriched creatinine has unequivocally shown that in DMSO-d6 solution it exists as amino tautomer (2-amino-1-methylimidazoline-4-one), which in the presence of acid is protonated at N-3. Free energies of activation of the amino group rotation in creatinine and its cation have been determined to be 56 kJ/mol(More)
In this paper, we continue the exploration of possibilities, limitations, and methodological problems of the studies based on measurements of the nuclear spin relaxation rates running via the scalar relaxation of the second kind (SC2) mechanism. The attention has been focused on the (13)C-(79)Br and (13)C-(81)Br systems in organic bromo compounds, which are(More)
ABSTRACT The synthesis of a novel supramolecular system comprising of branched polyethylenimine and cyclodextrin, is presented. The synthesis route is based on the self-assembly phenomena with the inclusion of solvent molecules. The systems are formed by a hydrogen-bonding network and host-guest type interactions between the building blocks. It was found(More)
1H NMR and 13C NMR spectra of uracil, thymine, 5-hydroxymethyluracil, 5,6-dihydrouracil, and 5,6-dihydrothymine in DMSO-d6 solutions have been measured. Additionally, molecular structures as well as NMR parameters of these compounds and their various solvates have been calculated using DFT B3LYP/6-311++G(2d,p) PCM(DMSO) method. The analysis of the chemical(More)
Triketone herbicides are inhibitors of 4-hydroxyphenylpyruvate dioxygenase (HPPD), a key enzyme of the tyrosine transformation pathway, common for plants and animals. One of these herbicides, 2-[2-nitro-4-(trifluoromethyl)benzoyl]-1,3-cyclohexanedione (NTBC), is so selective and efficient that it can be applied as a medicine in a hereditary metabolic(More)
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