Abstract Determination of the level and absolute configuration 2‐hydroxyglutaric acid in a patient's urine is method diagnosing two metabolic diseases. Such determination can be done with aid NMR spectroscopic methods. In this paper careful interpretation 1 H 13 C spectra metabolite its lactone measured under conditions used biomedical assays reported. The chemical shifts spin–spin coupling constants were derived using total lineshape analysis method. Copyright © 2002 John Wiley & Sons, Ltd.

(13)C nuclear magnetic resonance shielding constants have been calculated by means of density functional theory (DFT) for several organomercury compounds and halogen derivatives aliphatic aromatic compounds. Relativistic effects included through the four-component Dirac-Kohn-Sham (DKS) method, two-component Zeroth Order Regular Approximation (ZORA) DFT, DFT with scalar effective core potentials (ECPs). The relative shieldings analyzed in terms position carbon atoms respect to heavy atom...

Reaction of 1,3-diallylimidazolium bromide with 1,1′-dimethylnickelocene (NiCp′2) afforded [NiCp′(all2-NHC)]+Br– (1a) (all2-NHC = 1,3-diallylimidazol-2-ylidene) and NiCp′(all2-NHC)Br (1b), while the reaction chloride nickelocene gave NiCp(all2-NHC)Cl (2) [NiCp(all2-NHC)2]+Cl– (3). Molecular structures all four complexes have been established by single-crystal X-ray diffraction. 1H NMR spectra 1b indicated hindered rotation about Ni–carbene bond at room temperature, which resulted in...

1H and 13C NMR spectra of 2-acyl-substituted cyclohexane-1,3-diones (acyl = formyl, 1; 2-nitrobenzoyl, 2; 2-nitro-4-trifluoromethylbenzoyl, 3) lithium sodium potassium salts 1 have been measured. The compound 3, known as NTBC, is a life-saving medicine applied in tyrosinemia type I. optimum molecular structures the investigated objects solutions found using DFT method with B3LYP functional 6-31G** and/or 6-311G(2d,p) basis set. theoretical values parameters compounds calculated GIAO...

Abstract Owing to wide accessibility of the general utility quantum chemistry programs, theoretical calculations spectral parameters defining NMR spectra have become relatively easy for medium size molecules. This new and powerful tool allows investigators perform much deeper interpretation data gain information valuable structural studies. It is usually realized well understood that parameters, as any mechanical calculations, several limitations, difficult overcome, accuracy calculation...

The study concerns N-methyl-2-pyrrolidinone, N,N-dimethylformamide, 2-pyrrolidinone, N-methylformamide, and formamide in DMSO-d6 CDCl3 solutions. It has been shown that the results of DFT calculations [B3LYP and/or PBE0 6-311++G(2d,p), PCM] molecular geometries magnetic shielding are able to reproduce very well amide 1H NMR 13C chemical shifts measured these solvents provided specific solvation solute molecules their association taken into account also comparison experimental theoretical...

The values of the indirect nuclear spin–spin coupling constants for a series aliphatic fluorocompounds have been calculated using DFT-based methods and compared with experimental these parameters.

Three α-galactosides of d-pinitol: 1d-O-(α-d-galactopyranosyl)-(1→2)-4-O-methyl-chiro-inositol, 1, 1d-O-α-d-galactopyranosyl-(1→6)-O-α-d-galactopyranosyl-(1→2)-4-O-methyl-chiro-inositol, 2, and 1d-O-α-d-galactopyranosyl-(1→6)-O-α-d-galactopyranosyl-(1→6)-O-α-d-galactopyranosyl-(1→2)-4-O-methyl-chiro-inositol, 3, present in vetch seeds, were isolated, purified, quantitatively determined using column high-resolution gas chromatography. Their structures established by 1H 13C NMR 1D 2D...

Carbon-13 isotropic shielding constants and C–F spin–spin coupling for fluorobenzene, 3- 4-dimethylaminofluorobenzene as well their tricarbonylchromium complexes have been calculated using DFT methods.

Continuing studies based on measurements of the nuclear spin relaxation rates running via SC2 mechanism (scalar second kind), we present in this work results obtained for three molecules: 9-bromotriptycene, 1,3,5-tribromobenzene, and 1-(2-bromoethynyl)-4-ethynylbenzene which C-Br bond one C-H bonds are collinear. Separation saturation-recovery or inversion-recovery curves (13)C NMR signals bromine-bonded carbons investigated compounds two components has provided longitudinal these (79)Br-...

1H NMR and 13C spectra of uracil, thymine, 5-hydroxymethyluracil, 5,6-dihydrouracil, 5,6-dihydrothymine in DMSO-d6 solutions have been measured. Additionally, molecular structures as well parameters these compounds their various solvates calculated using DFT B3LYP/6-311++G(2d,p) PCM(DMSO) method. The analysis the chemical shift data for has shown that, indeed, DMSO they occur equilibrium mixtures free molecules which solute solvent are joined by NH···O or OH···O hydrogen bonds. populations...

Abstract Investigation of 15 N NMR spectra isotopically enriched creatinine has unequivocally shown that in DMSO‐d 6 solution it exists as amino tautomer (2‐amino‐1‐methylimidazoline‐4‐one), which the presence acid is protonated at N‐3. Free energies activation group rotation and its cation have been determined to be 56 kJ/mol 60 kJ/mol, respectively, 298 K, by performing simultaneous analysis lineshapes NH 2 proton signals whole set 1 H recorded various temperatures magnetic fields. These...

High-resolution (1)H NMR spectroscopy of body fluids has proved to be very useful in diagnostics inherited metabolic diseases, whereas (13)C remains almost unexploited. In this paper the application fivefold concentrated urine samples for diagnosis selected diseases is reported. Various marker metabolites were identified test from 33 patients suffering 10 different providing information which could crucial their diagnoses. Spectra accumulated 2 h or overnight when using spectrometers...

The enolization degrees of succinylacetone, an important heme biosynthesis inhibitor, have been determined in CDCl3 and water solutions using 1H NMR. solution structures SA investigated a combined NMR/theoretical [GIAO DFT PBE1PBE/6-311++G(2d, p) PCM] approach. populations both enolic forms undergoing enol−enol equilibriums for series unsymmetrical β-diketones established by quantitative comparison the experimental 13C NMR chemical shifts calculated shielding constants. Moreover, same method...

Magnetic shielding and indirect spin-spin coupling phenomena are tensorial properties both their isotropic anisotropic parts do affect NMR spectra. The involved interaction tensors, σ J, can nowadays be theoretically calculated, although the reliability of such methods in case parameters, Δσ ΔJ, systems involving heavy nuclei, yet demands testing. In this communication results experimental theoretical investigations bis(phenylethynyl)mercury (I) labeled with (13)C isotope at positions...

A methodology enabling investigation of a multicomponent tautomeric and acid-base equilibria by (13)C NMR spectroscopy supported theoretical calculations has been proposed. The effectiveness this method illustrated in study 2-oxopurine, 6-oxopurine (hypoxanthine), 8-oxopurine, 2,6-dioxopurine (xanthine) neutral alkaline aqueous solutions. For each compound series spectra were recorded at pH ranges which molecules, monoanions and/or dianions occurred dynamic equilibrium. carbon chemical...

Continuing studies based on measurements of the nuclear spin relaxation rates running via SC2 mechanism (scalar second kind), we present in this work results obtained for three bromo compounds: CBrCl3, (CH3)3CBr, and CBr4. A careful separation saturation-recovery curves, measured signals (13)C nuclei at 7.05 11.7 T two components, has provided longitudinal carbon (79)Br (81)Br containing isotopomers investigated compounds. These data have enabled experimental determination spin-spin coupling...

Orotic acid, a biologically important compound, can exist in aqueous solutions several ionic and tautomeric forms. Interpretation of the experimental (13)C NMR chemical shifts this compound based on results energy magnetic shielding calculations performed by DFT B3LYP/6-311++G(2d,p)/PCM method has shown that water diketo tautomers are dominant structural forms acid its anions. For neutral molecules anti conformation is preferable, monoanion occurs as conventional carboxylate anion, whereas...

Triketone herbicides are inhibitors of 4-hydroxyphenylpyruvate dioxygenase (HPPD), a key enzyme the tyrosine transformation pathway, common for plants and animals. One these herbicides, 2-[2-nitro-4-(trifluoromethyl)benzoyl]-1,3-cyclohexanedione (NTBC), is so selective efficient that it can be applied as medicine in hereditary metabolic disease - tyrosinemia type I. In this paper available information concerning molecular mechanism HPPD inhibition by NTBC, originating from experimental...