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Journal articles on the topic '13C NMR chemical'

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Published: 5 June 2025

Last updated: 1 August 2025

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1

NORDIN, H. LAJIS, and NIYAZ KHAN MOHAMMAD. "13C NMR Chemical Shifts of some 1,4-Disubstitutedbenzenes and Substituent Chemical Shifts for some Substituents." Journal of Indian Chemical Society Vol. 71, May 1994 (1994): 277–79. https://doi.org/10.5281/zenodo.5894775.

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<em>Department of Chemistry, University Pertanian Malaysia, 43400 UPM Serdang, Selangor Darnl Ehsan, Malaysia Manuscript received 19 May 1993, accepted 8 July 1993</em> 13C NMR Chemical Shifts of some 1,4-Disubstitutedbenzenes and Substituent Chemical Shifts for some Substituents

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2

G.B.Iskenderova and S.B.Serkerov. "Detection of 7-Demethylsuberozine in Resin of Roots of Ferulago setifolia C.Koch." Journal of Life Sciences and Biomedicine 69, no. 2 (2014): 37–39. https://doi.org/10.5281/zenodo.7434650.

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A crystalline substance with composition of C14H14O3 and m.p.of 134-135ºC (from hexane-chloroform) has been isolated by column chromatography from the rezin of roots of Ferulago setifolia C.Koch (Apiaceae Lindl.) collected in the phase of fruiting. On the basis of chemical and spectral data (IR-, 1 H-, 13C-, 13C Dept 135 NMR) of an initial substance and its acetyl derivative it was proved that the substance has a structure of 7-hydroxy-6-izopentenilcoumarin (7-demethylsuberozine).

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3

Semenov, Valentin, Dmitriy Samul'cev, and Leonid Krivdin. "1H AND 13C NMR SPECTRA OF STRYCHNOS ALKALOIDS: SELECTED NMR UPDATES." Bulletin of the Angarsk State Technical University 1, no. 14 (2020): 77–94. http://dx.doi.org/10.36629/2686-777x-2020-1-14-77-94.

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The PBE0/pcSseg-2//pcseg-2 calculations of 1H and 13C NMR chemical shifts were performed for a classical series of 12 Strychnos alkaloids (except for the earlier studied parent strychnine), namely akuammicine, isostrychnine, rosibiline, tsilanine, spermostrychnine, diaboline, cyclostrychnine, henningsamide, strychnosilidine, strychnobrasiline, holstiine, and icajine. It was found that calculated 1H and 13C NMR chemical shifts demonstrated markedly good correlations with available experimental data characterized by a mean absolute error of 0.22 ppm for the range of

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4

DE AMORIM, M. L. L., W. M. GODINHO, F. C. ARCHANJO, and C. F. F. GRAEL. "Chemical constituents of Pseudobrickellia brasiliensis leaves(Spreng.) R.M. King & H. Rob. (Asteraceae)." Revista Brasileira de Plantas Medicinais 18, no. 2 (2016): 408–14. http://dx.doi.org/10.1590/1983-084x/15_185.

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ABSTRACT Pseudobrickelliabrasiliensisis aspecies endemic toBrazil, popularlyknown as “arnica”/ “arnica-do-campo”/ “arnica-do-mato” and used for itsanalgesicand anti-inflammatoryproperties. The objective of this research was thephytochemical studyof the essential oilandhexaneandethyl acetateextracts of the leaves of this species. The essential oilwasextracted byhydrodistillation using a Clevengerapparatusand was analyzed byGC/MS, 25components were identified, with a predominance ofmonoterpenes. The extractswere subjected toclassicalchromatographyand the fractionswere analyzed byGC/MS, 1D 1H-NMR

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5

Tulyabaev, A. R., and L. M. Khalilov. "Quantum-Chemical Simulation of 13C NMR Chemical Shifts of Fullerene C60 Exo-Derivatives." Журнал физической химии 97, no. 9 (2023): 1272–77. http://dx.doi.org/10.31857/s004445372309025x.

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The 13C NMR chemical shifts of fullerene C60 exo-derivatives were calculated using quantum chemical hybrid functionals combined with Pople, Dunning correlation-consistent, and def2-TZVP split valence basis sets taking into account the solvent effect (polarizable continuum model). A relationship between theoretical and experimental 13C NMR chemical shifts (CSs) is assessed quantitatively to select a functional/basis set combination. It is found that the CAM-B3LYP/6-31G and M06L/6-31G combinations have the best convergence with experimental data in modeling the 13С NMR CSs of sp3 fullerene carbo

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6

Šnobl, Dobroslav, Antonín Lyčka, and Jaroslav Horyna. "13C NMR spectra of sodium naphthalenesulphonates." Collection of Czechoslovak Chemical Communications 50, no. 8 (1985): 1852–61. http://dx.doi.org/10.1135/cccc19851852.

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13C NMR spectra of thirteen sodium naphthalenesulphonates have been measured in deuterium oxide. The 13C chemical shifts have been assigned, and the nJ(13CH) coupling constants have been measured. Effect of SO3(-) group on the 13C NMR parameters is discussed.

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7

Gunawan, Ramdhan, and Asep Bayu Dani Nandiyanto. "How to Read and Interpret 1H-NMR and 13C-NMR Spectrums." Indonesian Journal of Science and Technology 6, no. 2 (2021): 267–98. http://dx.doi.org/10.17509/ijost.v6i2.34189.

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Nuclear magnetic resonance spectroscopy or NMR is a chemical instrument that can be used to evaluate the structure of a chemical compound other than FTIR, GC-MS, and HPLC. NMR spectroscopy commonly used for compound analysis is 1H-NMR and 13C-NMR. Techniques can be used to determine the structure conformation, the number of protons, and the number of carbons in the structure of a chemical compound. So far, there have been many publications related to the use of this spectroscopic technique. However, the steps in reading and interpreting the spectra of both 1H-NMR and 13C-NMR are not described

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8

TAKEGOSHI, K. "13C chemical shift in solid-state NMR." Journal of the Spectroscopical Society of Japan 37, no. 4 (1988): 287–88. http://dx.doi.org/10.5111/bunkou.37.287.

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9

Xia, Y., and H. Zhang. "13C NMR chemical shift prediction of diverse chemical compounds." SAR and QSAR in Environmental Research 30, no. 7 (2019): 477–90. http://dx.doi.org/10.1080/1062936x.2019.1619621.

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10

Schraml, Jan, Eva Petráková, Ján Hirsch, et al. "13C MAS NMR and 1H-29Si and 1H-13C heteronuclear correlation study of model xylooligosaccharides." Collection of Czechoslovak Chemical Communications 52, no. 10 (1987): 2460–73. http://dx.doi.org/10.1135/cccc19872460.

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Anomer structures of crystalline D-xylopyranose, all positional isomers of β-D-xylopyranosyl-D-xylopyranose and 2,4-di-β-D-xylopyranosyl-D-xylopyranose were determined by 13C MAS NMR spectroscopy. The saccharides were pertrimethylsilylated by different methods yielding different ratios of pertrimethylsilylated anomers. The NMR spectra (1H, 13C, and 29Si) were assigned by two-dimensional chemical shift correlations. In the anomeric mixtures complete overlap in parts of proton spectra is frequent. In such a case, samples with different anomer ratios considerably facilitate assignment of both 13C

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11

Kobayashi, J., K. Shimbo, Takaaki Kubota, and M. Tsuda. "Bioactive macrolides and polyketides from marine dinoflagellates." Pure and Applied Chemistry 75, no. 2-3 (2003): 337–42. http://dx.doi.org/10.1351/pac200375020337.

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Absolute stereochemistry of amphidinolides G and H, potent cytotoxic 27- and 26-membered macrolides, respectively, isolated from a marine dinoflagellate Amphidinium sp., was determined by X-ray diffraction analysis, synthesis of a degradation product, and chemical interconversion. Six new macrolides, amphidinolides H2~H5, G2, G3, and W, have been isolated from a marine dinoflagellate Amphidinium sp. (strain Y-42), and the structures were elucidated by 2D NMR data and chemical means. The structure-activity relationship of amphidinolide H-type macrolides for cytotoxicity was examined. The biosyn

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12

Pardoen, J. A., P. P. J. Mulder, E. M. M. van den Berg, and J. Lugtenburg. "Synthesis of 8-, 9-, 12-, and 13-mono-13C-retinal." Canadian Journal of Chemistry 63, no. 7 (1985): 1431–35. http://dx.doi.org/10.1139/v85-246.

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The 8-, 9-, 12-, and 13-mono-13C-retinals were synthesized with > 98% chemical purity and 93% 13C incorporation from 13C-labelled acetonitrile. Their 13C–13C and 13C–1H nmr coupling constants were determined.

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13

Aoki, Dan, Kenta Nomura, Masashi Hashiura, et al. "Evaluation of ring-5 structures of guaiacyl lignin in Ginkgo biloba L. using solid- and liquid-state 13C NMR difference spectroscopy." Holzforschung 73, no. 12 (2019): 1083–92. http://dx.doi.org/10.1515/hf-2019-0011.

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Abstract To discuss the macromolecular structure and properties of lignin, the complementary use of solid- and liquid-state nuclear magnetic resonance (NMR) combined with a specific 13C-enrichment technique may provide useful information. The 13C-enriched lignin was prepared by administering [guaiacyl ring-5(G5)-13C]-coniferin to a growing Ginkgo biloba L. shoot. The 13C-enriched cellulolytic enzyme lignin (EL) and its acetate prepared from the ginkgo shoot were examined by solid- and liquid-state 13C NMR spectroscopy. The 13C NMR spectrum derived only from the G5 carbon was obtained as a diff

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14

Chen, Xi, Andrey Smelter, and Hunter N. B. Moseley. "BaMORC: A Software Package for Accurate and Robust 13C Reference Correction of Protein NMR Spectra." Natural Product Communications 14, no. 5 (2019): 1934578X1984914. http://dx.doi.org/10.1177/1934578x19849142.

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We describe Bayesian Model Optimized Reference Correction (BaMORC), a software package that performs 13C chemical shifts reference correction for either assigned or unassigned peak lists derived from protein NMR spectra. BaMORC provides an intuitive command line interface that allows non-nuclear magnetic resonance (NMR) experts to detect and correct 13C chemical shift referencing errors of unassigned peak lists at the very beginning of NMR data analysis, further lowering the bar of expertise required for effective protein NMR analysis. Furthermore, BaMORC provides an application programming in

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15

Baldock, JA, JM Oades, AM Vassallo, and MA Wilson. "Incorporation of uniformly labeled 13C glucose carbon into the organic fraction of a soil - carbon balance and CP MAS 13C NMR Measurements." Soil Research 27, no. 4 (1989): 725. http://dx.doi.org/10.1071/sr9890725.

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The incorporation of uniformly labelled 13C-giucose into soil organic matter was followed using mass spectrometry to make carbon balance measurements, and using solid state CP/MAS 13C NMR (cross polarization/magic angle spinning 13C nuclear magnetic resonance) spectroscopy to determine changes in the chemical structure of the added 13C with time. A fine sandy loam soil was incubated in the presence and absence of the labelled 13C-glucose for up to 34 days at 22�C and a soil water matric potential of -33 kPa. Carbon balance measurements indicated that no priming effect of glucose addition on de

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16

Elguero, José, Alain Fruchier, María Luisa Jimeno, and Pedro Molina. "An Experimental Study of the 4hJ(31P–31P) Coupling Constant and the 12C/13C Isotope Effect on 31P in an Iminophosphorane-Substituted Proton Sponge." Journal of Chemical Research 2002, no. 1 (2002): 34–36. http://dx.doi.org/10.1177/1747519802200200103.

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The 13C NMR spectra of the bromide of the protonated iminophosphorane -substituted sponge 7 were recorded at different fields. Together with the use of 13C satellites of the 31P NMR spectrum, these experiments allow determination of a reasonable set of chemical shifts and coupling constants. The most interesting are a 4h JPP = 1.6 Hz, determined directly from the 31P NMR spectrum, which probably involves the hydrogen bond, and a 2Δ31P(13C) isotope shift of 9 ppb.

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17

Holeček, Jaroslav, Antonín Lyčka, Karel Handlíř, and Milan Nádvorník. "13C and 119Sn NMR spectra of diphenyl- and dibenzyltin(IV) compounds and their complexes." Collection of Czechoslovak Chemical Communications 55, no. 5 (1990): 1193–207. http://dx.doi.org/10.1135/cccc19901193.

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13C and 119Sn NMR spectra of diphenyl- and dibenzyltin(IV) compounds have been studied in solutions of coordinating and non-coordinating solvents. Regions of values of the δ(119Sn) chemical shifts have been determined which characterize individual types of coordination of the central tin atom. The values of 13C NMR spectral parameters, the δ(13C) chemical shifts and nJ(119Sn, 13C) coupling constants, have been used to describe the real shapes of coordination sphere of the central tin atom and to discuss the internal structure of the organic substituents and of the nature of their bonding linka

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18

Ananikov, Valentine. "Evaluation of 13C NMR spectra of cyclopropenyl and cyclopropyl acetylenes by theoretical calculations." Open Chemistry 2, no. 1 (2004): 196–213. http://dx.doi.org/10.2478/bf02476190.

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AbstractA convenient methodology was developed for a very accurate calculation of 13C NMR chemical shifts of the title compounds. GIAO calculations with density functional methods (B3LYP, B3PW91, PBE1PBE) and 6-311+G(2d,p) basis set predict experimental chemical shifts of 3-ethynylcyclopropene (1), 1-ethynylcyclopropane (2) and 1,1-diethynylcyclopropane (3) with high accuracy of 1–2 ppm. The present article describes in detail the effect of geometry choice, density functional method, basis set and effect of solvent on the accuracy of GIAO calculations of 13C NMR chemical shifts. In addition, t

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19

Gronski, Wolfram, Uwe Hoffmann, Gerald Simon, Andre Wutzler, and Ekkehard Straube. "Structure and Density of Crosslinks in Natural-Rubber Vulcanizates. A Combined Analysis by NMR Spectroscopy, Mechanical Measurements, and Rubber-Elastic Theory." Rubber Chemistry and Technology 65, no. 1 (1992): 63–77. http://dx.doi.org/10.5254/1.3538608.

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Abstract 13C-NMR MAS solid-state spectroscopy and 1H-NMR relaxation measurements have been applied for quantitative determination of crosslink density in sulfur-accelerated NR vulcanizates. It is shown that the 13C-NMR method is able to distinguish between monosulfidic crosslinks and polysulfldic structures; therefore a quantitative determination of chemical crosslinks was possible. An analysis of 13-NMR transversal relaxation measurements provided the network densities which were in good agreement with the results of the 13C-NMR measurements. Comparing stress-strain data with the spectroscopi

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20

Hughes, Donald W., Robert V. Gerard, and David B. MacLean. "An NMR study of the Lycopodium alkaloids, annotinine and annotine: verification of the annotine structure." Canadian Journal of Chemistry 67, no. 11 (1989): 1765–73. http://dx.doi.org/10.1139/v89-273.

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The Lycopodium alkaloids, annotinine and annotine, were examined by 1H and 13C NMR spectroscopy. Proton spectra were assigned by the application of double-quantum filtered phase-sensitive COSY and nuclear Overhauser enhancement difference spectra. These and other data confirmed the structure previously assigned to annotine. The 13C chemical shifts were consistent with the structural data derived from the proton spectra. The NMR data showed a good correlation with structures determined from molecular mechanics (MMX) calculations. Keywords: Lycopodium alkaloids 1H and 13C NMR, annotinine, annoti

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21

Rusnac, Roman, Andrei Ciursin, Sergiu Shova, Angela Sirbu, and Aurelian Gulea. "Synthesis and physical-chemical analysis of the coordination compounds of Cu(II) based on 3-ethoxysalicylaldehyde 4-cyclohexyl-thiosemicarbazone." Studia Universitatis Moldaviae. Seria Științe ale Naturii, no. 1(171) (September 2023): 194–205. http://dx.doi.org/10.59295/sum1(171)2023_26.

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In this article, methods of synthesis and physicochemical analysis of 5 coordination compounds based on Cu(II) ion and 3-ethoxysalicylic aldehyde 4-cyclohexyl-thiosemicarbazone are described. In the first step, the synthesis of the ligand was carried out by means of two classical methods with subsequent refinement, thus obtaining the H2L as a chelator of copper(II) ions. 1H, 13C and 15N-NMR spectroscopy, 13C-DEPT-135 NMR and 15N HSQC-NMR spectroscopy were applied to investigate the structure and geometry of the 3-ethoxysalicylic aldehyde 4-cyclohexyl-thiosemicarbazone. The synthesized substanc

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22

Agrawal, Pawan K., Chandan Agrawal, and Shravan Agrawal. "Carbon-13 NMR Chemical Shift of Methyl Group: A Useful Parameter for Structural Analysis of C-Methylated Flavonoids." Natural Product Communications 1, no. 11 (2006): 1934578X0600101. http://dx.doi.org/10.1177/1934578x0600101108.

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The 13C NMR resonances corresponding to the C-Me group of C-6 and/or C-8 C-methylated-flavonoids absorb between 6.7–10.0 ppm and typically between 6.7–8.7 ppm. A comparative 13C NMR study reflects that the 13C NMR chemical shifts reported for 6-hydroxy-5-methyl-3′,4′,5′-trimethoxyaurone-4-O-α-L-rhamnoside from Pterocarpus santalinus and 8-C-methyl-5,7,2′,4′- tetramethoxyflavanone from Terminalia alata are inconsistent with the assigned structures, and therefore need reconsideration.

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23

Krivdin, Leonid B. "Computational protocols for calculating 13C NMR chemical shifts." Progress in Nuclear Magnetic Resonance Spectroscopy 112-113 (June 2019): 103–56. http://dx.doi.org/10.1016/j.pnmrs.2019.05.004.

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24

Penner, Glenn H., and Roderick E. Wasylishen. "A carbon-13 CP/MAS nuclear magnetic resonance study of several 1,4-disubstituted benzenes in the solid state." Canadian Journal of Chemistry 67, no. 3 (1989): 525–34. http://dx.doi.org/10.1139/v89-080.

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The carbon-13 chemical shifts of several 1,4-disubstituted benzenes in the solid state are reported. At least one of the substituents is unsymmetrical and in most cases this leads to different 13C chemical shifts of C-2 and C-6 and in some cases to different shifts for C-3 and C-5. The 13C chemical shifts observed in the solid state are compared with those measured in solution and, where possible, with those obtained in low temperature solution studies where internal rotation of the unsymmetrical substituent is slow on the 13C chemical shift time scale. Agreement between the chemical shifts ob

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25

Djarmati, Zoltan, Ratko M. Jankov, János Csanádi, and Aleksandar Djordjevic. "The Isolation of Carnosic Acid 12-Methyl Ether from Salvia officinalis L. and NMR Study of Its Methyl Ester." Collection of Czechoslovak Chemical Communications 58, no. 8 (1993): 1919–24. http://dx.doi.org/10.1135/cccc19931919.

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In continuation of our studies on the chemical compositions of the aerial parts of cultivated Salvia officinalis L., we have isolated the title substance for the first time in this type of Sage. The structure of this isolated compound was established by spectroscopic data and some chemical reactions. Investigation of 1H and 13C NMR, homonuclear (COSY) (1H-1H), heteronuclear (HETCOR) (1H-13C), and selective INEPT spectra, permitted the unambiguous assignment of the 1H and 13C NMR spectra, what gave the possibility to resolve signals of similar natural products.

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26

Rakhmatullin, I., S. Efimov, A. Klochkov, V. Klochkov, and M. Varfolomeev. "NMR STRUCTURAL-GROUP CHARACTERISTICS AND DETAILED SHIFT RANGES IN LIGHT, HEAVY AND CATALYZED OILS." Znanstvena misel journal, no. 69 (August 19, 2022): 7–11. https://doi.org/10.5281/zenodo.7009133.

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Application of high resolution 13C nuclear magnetic resonance (NMR) spectroscopy to characterize of light, heavy and catalyzed oils was demonstrated. Molar fractions of primary, secondary, quaternary, tertiary, aromatic groups, aromatic factor and average hydrocarbon chain length of aliphatic hydrocarbons of these oil samples according to 13C NMR spectra were determined. The received parameters indicate about the success of the catalytic treatment of the studied heavy oil sample. The detailed assignment of the 13C NMR signals and their comparison between light, heavy and catalyzed oil samples

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27

Buděšínský, Miloš, and David Šaman. "Identification of acyl groups occurring in sesquiterpene lactones: Proton and carbon-13 NMR study." Collection of Czechoslovak Chemical Communications 52, no. 2 (1987): 453–75. http://dx.doi.org/10.1135/cccc19870453.

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Characteristic 1H NMR parameters of 88 acyl groups, hitherto found as ester substituents in natural sesquiterpenic lactones, were determined from the measured spectra as well as literature data. Characteristic 13C NMR chemical shifts for 45 acyl groups were obtained in the same way; for the remaining acyls with hitherto unknown 13C NMR data the values were calculated on the basis of semiempirical relationships.

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28

Cravero, Raquel M., Guillermo R. Labadie, and Manuel González Sierra. "The determination of the stereochemistry of epoxides located at the 5,6-positions of decalinic systems: An empirical method based on 13C NMR chemical shifts." Canadian Journal of Chemistry 80, no. 7 (2002): 774–78. http://dx.doi.org/10.1139/v02-107.

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The 13C NMR spectra of a series of 5,6-epoxides in decalinic systems were studied. The interpretation of the chemical shifts allowed us to formulate an empirical rule to predict the epoxide stereochemistry. A discussion of the scope and limitations of this method and its extension to larger carbon skeletons is also presented.Key words: epoxide stereochemistry, 13C NMR, NMR, decalinic systems, oxiranes.

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29

Cohen, Ryan D., Jared S. Wood, Yu-Hong Lam, et al. "DELTA50: A Highly Accurate Database of Experimental 1H and 13C NMR Chemical Shifts Applied to DFT Benchmarking." Molecules 28, no. 6 (2023): 2449. http://dx.doi.org/10.3390/molecules28062449.

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Density functional theory (DFT) benchmark studies of 1H and 13C NMR chemical shifts often yield differing conclusions, likely due to non-optimal test molecules and non-standardized data acquisition. To address this issue, we carefully selected and measured 1H and 13C NMR chemical shifts for 50 structurally diverse small organic molecules containing atoms from only the first two rows of the periodic table. Our NMR dataset, DELTA50, was used to calculate linear scaling factors and to evaluate the accuracy of 73 density functionals, 40 basis sets, 3 solvent models, and 3 gauge-referencing schemes

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30

Danihel, Ivan, Ján Imrich, Dušan Košťík, Pavol Kristian, and Gabriela Barančíková. "13C NMR spectra and substituent effects of meta and para substituted benzoyl isothiocyanates." Collection of Czechoslovak Chemical Communications 50, no. 6 (1985): 1422–31. http://dx.doi.org/10.1135/cccc19851422.

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13C NMR spectra have been studied of 20 meta and para substituted benzoyl isothiocyanates and corresponding benzoyl chlorides. The 13C SCS values of the carbon atom in NCS group have been found to correlate linearly with the Hammet σm,p constants of the substituents as well as with the corresponding π electron charges. The 13C SCS (substituent chemical shift) values of the carbonyl carbon atom of the compounds investigated are little sensitive to substituent effects and are analyzed on the basis of the dual-substituent-parameter approach. Also discussed are the intercorrelation relations of th

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31

PRESTON, C. M., S. E. SHIPITALO, R. L. DUDLEY, C. A. FYFE, S. P. MATHUR, and M. LEVESQUE. "COMPARISON OF 13C CPMAS NMR AND CHEMICAL TECHNIQUES FOR MEASURING THE DEGREE OF DECOMPOSITION IN VIRGIN AND CULTIVATED PEAT PROFILES." Canadian Journal of Soil Science 67, no. 1 (1987): 187–98. http://dx.doi.org/10.4141/cjss87-016.

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Solid-state 13C CPMAS NMR was used to examine organic soils from virgin, 5-yr and 15-yr cultivated sites. In agreement with previous studies using other techniques, the chemical effects of cultivation were essentially confined to the plough layer. Cultivated sites had less carbohydrate, and increased lipid and methoxyl carbon; these changes were similar to those found with depth, due to natural decomposition. Changes in aromatic and phenolic carbon with depth or years of cultivation were small. When the NMR data were compared with other indicators of decomposition, there were no correlations b

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32

Chacko, V. P., and R. G. Weiss. "Intracellular pH determination by 13C-NMR spectroscopy." American Journal of Physiology-Cell Physiology 264, no. 3 (1993): C755—C760. http://dx.doi.org/10.1152/ajpcell.1993.264.3.c755.

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A noninvasive method for the determination of pH by the 13C-nuclear magnetic resonance (NMR) chemical shift of the C-3 carbon of sn-glycerol 3-phosphate is described. Nonlinear least-squares analysis of the chemical shift variation of the C-3 resonance of sn-glycerol 3-phosphate with pH at 37 degrees C in solutions and in perchloric acid extracts of tissue yielded a pKa of 6.2, making it a very sensitive indicator of pH in the approximate range of 5-7. Intracellular pH determined by the present 13C-NMR method correlated well with simultaneous measurements of pH by 31P-NMR spectroscopy over a w

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33

Friedrich, Jan O., and Roderick E. Wasylishen. "A 1H and 13C nuclear magnetic resonance study of carnosine." Canadian Journal of Chemistry 64, no. 11 (1986): 2132–38. http://dx.doi.org/10.1139/v86-351.

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The proton and carbon-13 resonance signals of carnosine (β-alanyl-L-histidine) were unambiguously assigned using a variety of nmr techniques including proton–carbon chemical shift correlations, titrations of nmr chemical shifts, coupling constants, and isotope shifts. From the 13C nmr titration, carnosine's three pKa values were estimated to be 2.7, 7.1, and 10.6, and it was found that the imidazole ring existed predominantly as the 3-H tautomer in basic solution. Conformational information about the Cα—Cβ bond and about the N—Cα bond was deduced from observed 3J(C,H) and 3J(H,H) values. The 1

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34

Canton, Marine, Jane Hubert, Stéphane Poigny, et al. "Dereplication of Natural Extracts Diluted in Glycerin: Physical Suppression of Glycerin by Centrifugal Partition Chromatography Combined with Presaturation of Solvent Signals in 13C-Nuclear Magnetic Resonance Spectroscopy." Molecules 25, no. 21 (2020): 5061. http://dx.doi.org/10.3390/molecules25215061.

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For scientific, regulatory, and safety reasons, the chemical profile knowledge of natural extracts incorporated in commercial cosmetic formulations is of primary importance. Many extracts are produced or stabilized in glycerin, a practice which hampers their characterization. This article proposes a new methodology for the quick identification of metabolites present in natural extracts when diluted in glycerin. As an extension of a 13C nuclear magnetic resonance (NMR) based dereplication process, two complementary approaches are presented for the chemical profiling of natural extracts diluted

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35

Wrackmeyer, Bernd. "Organoboranes and tetraorganoborates studied by 11B and 13C NMR spectroscopy and DFT calculations." Zeitschrift für Naturforschung B 70, no. 6 (2015): 421–24. http://dx.doi.org/10.1515/znb-2015-0040.

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AbstractCare should be taken on recording the sometimes elusive 13C NMR signals for boron-bonded carbon atoms, since it is easy to extract information about coupling constants 1J(13C,11B) by measuring the respective line widths of 13C(B-C) and 11B NMR signals. This information can be confirmed by quantum-chemical calculations [B3LYP (6-311+G(d,p) level of theory] of nJ(13C,11B) in organoboranes and tetraorganoborates. For the latter, the signs for n = 2, 3, 4 were experimentally determined.

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36

Johann, Susana, Artur Smânia-Jr, Moacir G. Pizzolatti, Jan Schripsema, Raimundo Braz-Filho, and Alexsandro Branco. "Complete ¹H and 13C NMR assignments and anti fungal activity of two 8-hydroxy flavonoids in mixture." Anais da Academia Brasileira de Ciências 79, no. 2 (2007): 215–22. http://dx.doi.org/10.1590/s0001-37652007000200004.

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A mixture of the two new flavonols 8-hydroxy-3, 4', 5, 6, 7-pentamethoxyflavone (1) and 8-hydroxy-3, 3', 4', 5, 6, 7-hexamethoxyflavone (2) was isolated from a commercial sample of Citrus aurantifolia. An array of one- (¹HNMR, {¹H}-13C NMR, and APT-13C NMR) and two-dimensional NMR techniques (COSY, NOESY, HMQC and HMBC) was used to achieve the structural elucidation and the complete ¹H and 13C chemical shift assignments of these natural compounds. In addition, the antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated.

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37

Tulyabaeva, L. I., R. R. Salakhutdinov, A. R. Tulyabaev, T. V. Tyumkina, and M. F. Abdullin. "Cp2TiCl2-Catalyzed Interaction of Methylenecycloalkane with BF3·THF." Žurnal organičeskoj himii 60, no. 1 (2024): 75–85. https://doi.org/10.31857/s0514749224010065.

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The Cp2TiCl2-catalyzed interaction of methylenecycloalkanes with BF3·THF in tetrahydrofuran was carried out for the first time with the formation of target 1-fluoro-1-boraspirocarbocycles and also isomerization products of a starting monomer (1-methylcycloalk-1-enes). The structure of reaction products was elucidated using one- (1H, 13C Dept, 11B, 19F) and two-dimensional (COSY, HSQC, HMBC) NMR spectroscopy, mass spectrometry combined with quantum-chemical calculations of 13C NMR chemical shifts.

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38

Tulyabaeva, L. I., R. R. Salakhutdinov, A. R. Tulyabaev, T. V. Tyumkina, and M. F. Abdullin. "Interaction of Methylenecycloalkanes with BF3·THF Catalyzed by 2TiCl2." Журнал органической химии 59, no. 9 (2023): 1158–67. http://dx.doi.org/10.31857/s0514749223080069.

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The Cp2TiCl2-catalyzed interaction of methylenecycloalkanes with BF3·THF in tetrahydrofuran was carried out for the first time with the formation of target 1-fluoro-1-boraspirocarbocycles and also isomerization products of a starting monomer (1-methylcycloalk-1-enes). The structure of reaction products was elucidated using one(1H, 13C Dept, 11B, 19F) and two-dimensional (COSY, HSQC, HMBC) NMR spectroscopy, mass spectrometry combined with quantum-chemical calculations of 13C NMR chemical shifts.

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39

Stoitsov, Dimitar, Marin Marinov, Plamen Penchev, Petya Marinova, and Neyko Stoyanov. "5′-Oxospiro-(fluorene-9,4′-imidazolidine)-2′-thione." Molbank 2024, no. 3 (2024): M1864. http://dx.doi.org/10.3390/m1864.

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The structure verification of 5′-oxospiro-(fluorene-9,4′-imidazolidine)-2′-thione by NMR is reported. Toward this aim, 2D NMR techniques including 1H-1H COSY, HMQC, and HMBC experiments were used to assist with the assignment of the 1H and 13C chemical shifts for the corresponding structure. The mutual interpretation of the 1D and 2D NMR spectra ensured a complete and accurate 1H and 13C NMR data assignment for 5′-oxospiro-(fluorene-9,4′-imidazolidine)-2′-thione.

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40

Joshi, Balawant S., John K. Wunderlich, and S. William Pelletier. "13C Nuclear magnetic resonance spectroscopy in the elucidation of structures of diterpenoid alkaloids." Canadian Journal of Chemistry 65, no. 1 (1987): 99–103. http://dx.doi.org/10.1139/v87-016.

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13C Nuclear magnetic resonance spectroscopy is an exceptionally useful tool for the structure determination of diterpenoid alkaloids. A detailed study of the 1H and 13C nmr spectra of aconitine and 3-deoxyaconitine has permitted definite assignments to all the carbon atoms of the molecule. Chemical shift revisions have been suggested for certain carbon atoms of the C19-diterpenoid alkaloids. Chemical examination of Aconitumcolumbianum Nutt. ssp. columbianum, A. forrestii Stapf, Delphiniumtatsienense Franch., and D. vestitum Wall, resulted in the isolation of several new C19-diterpenoid alkaloi

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41

Heikkinen, Harri A., Sofia M. Backlund, and Hideo Iwaï. "NMR Structure Determinations of Small Proteins Using only One Fractionally 20% 13C- and Uniformly 100% 15N-Labeled Sample." Molecules 26, no. 3 (2021): 747. http://dx.doi.org/10.3390/molecules26030747.

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Uniformly 13C- and 15N-labeled samples ensure fast and reliable nuclear magnetic resonance (NMR) assignments of proteins and are commonly used for structure elucidation by NMR. However, the preparation of uniformly labeled samples is a labor-intensive and expensive step. Reducing the portion of 13C-labeled glucose by a factor of five using a fractional 20% 13C- and 100% 15N-labeling scheme could lower the total chemical costs, yet retaining sufficient structural information of uniformly [13C, 15N]-labeled sample as a result of the improved sensitivity of NMR instruments. Moreover, fractional 1

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42

Wang, Zhi, Yimin Xie, and Boxuan Zhao. "Formation and Chemical Structure of Carbon-13 Tracer Lignin-Carbohydrate Complexes (LCCs) During Kraft Pulping." Molecules 30, no. 5 (2025): 1077. https://doi.org/10.3390/molecules30051077.

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In this study, a modified synthetic method for labeling a lignin dimer (guaiacylglycerol-β-guaiacyl ether-[α-13C]) was developed. The chemical structure of the target compound was analyzed using 1H-NMR, 13C-NMR, and other analytical techniques. Then, the 13C-labeled phenolic lignin model compound was subjected to kraft pulping in the presence of xylose. Finally, the resulting reaction products were fractionated using acid precipitation and ethyl acetate extraction, and each fraction was analyzed by carbon-13 nuclear magnetic resonance (13C-NMR) and two-dimensional heteronuclear multiple quantu

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43

HAYASE, Fumitaka, Seon Bong KIM, and Hiromichi KATO. "Analyses of the chemical structures of melanoidins by 13C NMR, 13C and 15N CP-MAS NMR spectrometry." Agricultural and Biological Chemistry 50, no. 8 (1986): 1951–57. http://dx.doi.org/10.1271/bbb1961.50.1951.

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ARSHAD, M. A., J. A. RIPMEESTER, and M. SCHNITZER. "ATTEMPTS TO IMPROVE SOLID STATE 13C NMR SPECTRA OF WHOLE MINERAL SOILS." Canadian Journal of Soil Science 68, no. 3 (1988): 593–602. http://dx.doi.org/10.4141/cjss88-057.

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This study describes a number of different preparation techniques for recording solid state 13C NMR spectra of whole mineral soils. Removal of paramagnetic Fe3+ improves the quality of 13C NMR spectra of whole soils and of particle size fractions. The C:Fe ratio appears to be an important indicator for obtaining satisfactory 13C NMR spectra of whole soils and fractions separated from them. If the C:Fe ratio is >> 1, the quality of the spectrum will be good; if the ratio is > 1, a reasonable spectrum will be obtained, but if the ratio is < 1, the spectrum will be poor. Organic-matte

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45

Xie, Yimin, Yanchao Liu, Chen Jiang, Hongfei Wu, and Shuying Bi. "The existence of cellulose and lignin chemical connections in ginkgo traced by 2H-13C dual isotopes." BioResources 15, no. 4 (2020): 9028–44. http://dx.doi.org/10.15376/biores.15.4.9028-9044.

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To elucidate the covalent association between the celluloses and lignins found in gymnosperms, they were labeled with stable isotopes (deuterium and carbon-13) at specific positions and traced via mass spectroscopy and nuclear magnetic resonance (NMR). Both the 2H-labeled cellulose precursor (UDP-glucose-[6-2H2]) and the 13C-labeled lignin precursor (coniferin-[α-13C]) were added to a growing ginkgo plant, in combination with a 4-coumarate-CoA ligase inhibitor. The detection of abundance of 13C and 2H revealed that the lignin precursor and cellulose precursor deposited more actively in 300 to

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46

Petráková, Eva, Jan Schraml, Ján Hirsch, Magdalena Kvíčalová, Jan Zelený, and Václav Chvalovský. "Analysis of oligosaccharides. 29Si and 13C NMR spectra of pertrimethylsilylated oligosaccharides derived from xylopyranose." Collection of Czechoslovak Chemical Communications 52, no. 6 (1987): 1501–13. http://dx.doi.org/10.1135/cccc19871501.

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29Si and 13C chemical shifts are reported for a series of 30 pertrimethylsilylated oligosaccharides containing xylopyranosyl unit. The number of lines in 29Si NMR spectra is in all cases in agreement with the number of hydroxyl groups present in the parent compound prior to trimethylsilylation. The results demonstrate the usefulness of 29Si NMR spectroscopy for the analysis of oligosaccharides and other polyfunctional compounds. The validity of direct additivity of 13C chemical shifts is tested on some model trisaccharides.

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47

Lagerquist, Lucas, Jani Rahkila, and Patrik Eklund. "Determination of chemical shifts in 6-condensed syringylic lignin model compounds." Holzforschung 76, no. 3 (2021): 294–98. http://dx.doi.org/10.1515/hf-2021-0093.

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Abstract A small library of 6-substituted syringyl model compounds with aliphatic, carboxylic, phenylic, benzylic alcohols and brominated substituents were prepared. The influence of the substituents on the chemical shifts of the compounds was analyzed. All of model compounds showed a characteristic increase in the 13C NMR chemical shift of the methoxy group vicinal to the substitution. This 13C NMR peak and its corresponding correlation peak in HSQC could potentially be used to identify 6-condensation in syringylic lignin samples.

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Agrawala, Pranav. "Analyzing Carbon-13 NMR Spectra to Predict Chemical Shifts of Carbon Compounds using Machine Learning Algorithms." Morganton Scientific 1 (June 27, 2024): 5–9. http://dx.doi.org/10.62329/vrhv7044.

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Nuclear Magnetic Resonance (NMR) is a fundamental tool in chemistry for elucidating the molecular structure of unidentified substances. The evaluation of 13C NMR spectra can be challenging due to the numerous factors that affect the peaks and their locations (chemical shifts). Chemists can use NMR spectroscopy in synthesizing new molecules to confirm the identity of the molecule produced. Since the NMR spectrum for the molecule does not exist, the chemists cannot compare their spectra with preexisting spectra to verify their results. To address this, an algorithm that predicts the chemical shi

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Lolita, G. Lagurin, Daniel J. Magsalin John, R. Zosa Anthony, and M. Dayrit Fabian. "Chemical profiling and chemical standardization of Vitex negundo using 13C NMR." Journal of Medicinal Plants Research 11, no. 1 (2017): 11–21. http://dx.doi.org/10.5897/jmpr2015.6298.

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Dickson, Ross M., Michael S. McKinnon, James F. Britten, and Roderick E. Wasylishen. "A 13C and 15N nuclear magnetic resonance study of solid ammonium thiocyanate." Canadian Journal of Chemistry 65, no. 5 (1987): 941–46. http://dx.doi.org/10.1139/v87-159.

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The static 13C nmr powder pattern for solid ammonium thiocyanate is analyzed to obtain the 13C chemical shielding anisotropy, 321 ± 7 ppm, and the 13C–14N dipolar splitting, 1295 ± 25 Hz. Slow magic angle spinning 15N nmr experiments are analyzed to obtain a nitrogen chemical shielding anisotropy of 415 ± 15 ppm. The 13C–14N dipolar splitting leads to an effective C—N bond length of 1.19 ± 0.01 Å, in good agreement with the value of 1.176 Å reported from accurate X-ray and neutron crystallographic studies. In solid NH4NCS absolute values of the average shielding constants [Formula: see text] a

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