Nitrogen-15 Nuclear Magnetic Resonance Spectra Research Articles

Resolving the Regioregularity of Poly(N-n-hexyl-N'-phenylcarbodiimide) via Nitrogen-15 Labeling.

Nitrogen-15 nuclear magnetic resonance (NMR) spectroscopy and infrared spectroscopy (IR) were performed on an isotope-enriched poly(N-n-hexyl-N'-phenylcarbodiimide) to determine directly the connectivity and regioregularity of a polymer. Up to this point, the imine, C═N, IR stretch at 1660-1620 cm-1 was thought to be a sufficient handle to elucidate the presence or absence of a regioregular microstructure; however, recent findings cast some uncertainties when expanded to all polycarbodiimides. Therefore, an enriched 15N NMR study was undertaken to unambiguously resolve that a N-n-hexyl-N'-phenylcarbodiimide, when polymerized with a 2,2,2-trifluoroethoxide trichlorotitanium(IV) catalyst in chloroform, will produce a completely regioregular polymer. The only regioisomer present is the one in which the phenyl pendant group is positioned on the imino-nitrogen. The study was expanded to a chiral, (R)-BINOL-Ti(IV)-diisopropoxide catalyst which revealed no change in the regioisomer or the degree of regioregularity. In addition to 15N NMR spectra, the IR imine stretch exhibited isotope shifts for poly(N-n-hexyl-N'-phenylcarbodiimide) when labeled on both imino- and amino-nitrogen or solely the imino-nitrogen of ∼11 cm-1; however, no shift was manifested when labeling was restricted to the amino-nitrogen.

The Structure of Solid Copper(I) Cyanide: A Multinuclear Magnetic and Quadrupole Resonance Study

Carbon-13 and nitrogen-15 nuclear magnetic resonance (NMR) spectra of solid copper(I) cyanide present a clear picture of its molecular structure as comprising linear, polymeric chains: [−Cu−N−C−]n. Copper-63/65 nuclear quadrupole resonance reveals that the cyanide ligands are subject to “head-tail” disorder. Magic-angle spinning NMR spectra are analyzed by accounting for the quadrupolar effects of neighboring copper nuclei to yield one-bond indirect spin−spin coupling constants, 1J(63Cu,13C) ≈ +725 Hz and 1J(63Cu,15N) ≈ −250 Hz, and effective dipolar coupling constants, Reff(63Cu,13C) ≈ +1200 Hz and Reff(63Cu,15N) ≈ −460 Hz. The dipolar coupling data correspond to internuclear separations of rCu,C ≈ 1.88 A and rCu,N ≈ 1.92 A. The observation of axially symmetric 15N and 13C chemical shielding tensors in NMR spectra of nonspinning samples provides compelling evidence for the structural linearity of CuCN chains. Conclusions based on experimental data are supported by ab initio calculations of chemical shie...

A 14N and 15N Nuclear Magnetic Resonance Study of Nitrogen Metabolism in Shoot-Forming Cultures of White Spruce (Picea glauca) Buds

Nitrogen-14 and nitrogen-15 nuclear magnetic resonance (NMR) spectra were recorded for freshly dissected buds of Picea glauca and for buds grown for 3, 6 and 9 weeks on shoot-forming medium. Resonances for Glu (and other alphaNH(2) groups), Pro, Ala, and the side chain groups in Gln, Arg, Orn, and gamma-aminobutyric acid could be detected in in vivo(15)N NMR spectra. Peaks for alpha-amino groups, Pro, NO(3) (-) and NH(4) (+) could also be identified in (14)N NMR spectra. Perfusion experiments performed for up to 20 hours in the NMR spectrometer showed that (15)N-labeled NH(4) (+) and NO(3) (-) are first incorporated into the amide group of Gln and then in the alphaNH(2) pool. Subsequently, it also emerges in Ala and Arg. These data suggest that the glutamine synthetase/ glutamate synthase pathway functions under these conditions. The assimilation of NH(4) (+) is much faster than that of NO(3) (-). Consequently after 10 days of growth more than 70% of the newly synthesized internal free amino acid pool derives its nitrogen from NH(4) (+) rather than NO(3) (-). If NH(4) (+) is omitted from the medium, no NO(3) (-) is taken up during 9 weeks and the buds support limited growth by utilizing their endogenous amino acid pools. It is concluded that NH(4) (+) and NO(3) (-) are both required for the induction of nitrate- and nitrite reductase.

15N NMR Spectra of Cobalt(III) Complexes Containing 15NO2−

Abstract The nitrogen-15 nuclear magnetic resonance spectra of the cobalt(III) complexes containing 15NO2− were first measured; the coordination chemical shifts, Δδ (=δcomplex–δfree), were found to be from 135.0 to 161.5 ppm. The relationship between Δδ and the geometrical configuration was discussed in terms of the paramagnetic anisotropy of the cobalt(III) ion.

Coordination shifts in nitrogen-15 nuclear magnetic resonance spectra of glycinato and ethylenediamine ligands in cobalt(III) complexes

Coordination shifts in nitrogen-15 nuclear magnetic resonance spectra of glycinato and ethylenediamine ligands in cobalt(III) complexes

ChemInform Abstract: CARBON‐13 AND NITROGEN‐15 NUCLEAR MAGNETIC RESONANCE SPECTRA OF MEISENHEIMER COMPLEXES OF 1,3,5‐TRINITROBENZENE

Chemischer InformationsdienstVolume 13, Issue 24 Article ChemInform Abstract: CARBON-13 AND NITROGEN-15 NUCLEAR MAGNETIC RESONANCE SPECTRA OF MEISENHEIMER COMPLEXES OF 1,3,5-TRINITROBENZENE V. MACHACEK, V. MACHACEKSearch for more papers by this authorV. STERBA, V. STERBASearch for more papers by this authorA. LYCKA, A. LYCKASearch for more papers by this authorD. SNOBL, D. SNOBLSearch for more papers by this author V. MACHACEK, V. MACHACEKSearch for more papers by this authorV. STERBA, V. STERBASearch for more papers by this authorA. LYCKA, A. LYCKASearch for more papers by this authorD. SNOBL, D. SNOBLSearch for more papers by this author First published: June 15, 1982 https://doi.org/10.1002/chin.198224093AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume13, Issue24June 15, 1982 RelatedInformation

The carbon-13 and nitrogen-15 nuclear magnetic resonance spectra of uroporphyrinogens I and III

Due to their sensitivity to light and air, porphyrinogens are not normally isolated, but are routinely analyzed by oxidation to the corresponding porphyrin. We report herein the 13C- and 15N-NMR spectra of uroporphyrinogens I and III in their “native state”, multiply labelled with 13C and 15N, and at natural abundance ( 13C only).

Qualitative aspects of hydrogen-deuterium exchange in the proton, carbon-13, and nitrogen-15 nuclear magnetic resonance spectra of viomycin in aqueous solution

The 1H, 13C, and 15N high field nuclear magnetic resonance spectra of the cyclic peptide viomycin have been fully assigned using homo- and heteronuclear double resonance experiments and pH effects. In addition it is shown how the two- and three-bond H-D isotope effects upon carbonyl resonances may assist in their assignment. The resistance to exchange with solvent water of the amide proton involved in the transannular hydrogen bond is observed directly in the 1H spectra, via the isotope effect on a carbonyl resonance in the 13C spectra, and via the one-bond 1H couppling in the 15N spectra.

ChemInform Abstract: NITROGEN‐15 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY. NATURAL ABUNDANCE. NITROGEN‐15 NUCLEAR MAGNETIC RESONANCE SPECTRA OF ENAMINES

Chemischer InformationsdienstVolume 8, Issue 42 Physical Organic Chemistry ChemInform Abstract: NITROGEN-15 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY. NATURAL ABUNDANCE. NITROGEN-15 NUCLEAR MAGNETIC RESONANCE SPECTRA OF ENAMINES P. W. WESTERMAN, P. W. WESTERMANSearch for more papers by this authorJ. D. ROBERTS, J. D. ROBERTSSearch for more papers by this author P. W. WESTERMAN, P. W. WESTERMANSearch for more papers by this authorJ. D. ROBERTS, J. D. ROBERTSSearch for more papers by this author First published: October 18, 1977 https://doi.org/10.1002/chin.197742045Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume8, Issue42October 18, 1977 RelatedInformation

Nitrogen-15 magnetic resonance spectroscopy. Natural-abundance nitrogen-15 spectra of some 2-amino-2-deoxy-D-hexose derivatives.

The nitrogen-15 nuclear magnetic resonance spectra of some 2-amino-2-deoxj D-hexose drochlorides and 2-acetamido-2-deoxy-D-hexoses and N-benzoyl-D-glucosamine are reported. The differences in chemical shifts for the various hexopyranose structures are discussed in terms of steric, stereoelectronic, and hydrogen-bonding effects. These model compounds were used to study substituent effects related to amino sugar containing polysaccharides and antibiotics.