2D Heteronuclear Single Quantum Correlation Research Articles

1D and 2D NMR studies of N-vinylcarbazole/butyl methacrylate copolymers

Copolymers containing N-vinylcarbazole (V) and butyl methacrylate (B) units of different compositions were synthesized and their compositions were determined from quantitative 13C{ 1H} NMR spectroscopy. The reactivity ratios of the comonomers were estimated using the Kelen–Tudos and non-linear error in variable methods. The complete spectral assignment in terms of compositional and configurational sequences of the overlapping 1H and 13C{ 1H} spectra of the copolymers were done with the help of distortionless enhancement by polarization transfer, 2D heteronuclear single quantum correlation and total correlated spectroscopy experiments.

Complete Assignment of 1H and 13C NMR Spectra of Methacrylonitrile/Methylmethacrylate Copolymers

Methacrylonitrile/methylmethacrylate (A/M) copolymers were prepared by bulk polymerization. The 13C DEPT-135 (distortionless enhancement by polarization transfer) spectrum was used to differentiate between the carbon resonance signals of methyl, methoxy, and methylene units in the copolymers (A/M). Comonomer reactivity ratios were determined using Kelen–Tudos and non-linear error in variable methods. 2D heteronuclear single quantum correlation (HSQC) and total correlated spectroscopy (TOCSY) spectra were used to resolve the complex 1H NMR spectrum.

Microstructure determination of poly ( trans-4-acryloyloxyazobenzene) by n.m.r. spectroscopy.

The microstructure of poly( trans-4-acryloyloxyazobenzene) P(AB) homopolymer, prepared by solution polymerization using AlBN as initiator is analysed by one- and two-dimensional NMR spectrotcopy. Sequence distribution was calculated from 13 C{ 1 H} n.m.r. spectrum of the homopolymer. A 13 C distortionless enhancement by polarization transfer spectrum was used to differentiate between the resonance signals of methine and methylene units in the homopolymer. The triad sequence distribution of poly( trans-4-acryloyloxyazobenzene) P(AB), determined from carbonyl resonance of the homopolymer, is in good agreement with the triad concentrations calculated from the Bernoullian statistical model. 2D heteronuclear single quantum correlation (HSQC) and correlated spectroscopy (COSY) spectroscopy was used to analyse the complex 1 H n.m.r. spectrum. Homonuclear 2D TOCSY n.m.r. spectroscopy was used to ascertain the various configurational sequence of the poly( trans-4-acryloyloxyazobenzene) P(AB) homopolymer. 2D NOESY experiment was carried out to determine one of the many probable conformations of the homopolymer in solution state.

Microstructure of vinylidene chloride-ethyl acrylate copolymers by one- and two-dimensional NMR spectroscopy

Vinylidene chloride/ethyl acrylate (V/E) copolymers were prepared by photopolymerization using uranyl ion as a photosensitizer at room temperature. Copolymers were characterized by chlorine estimation, gel permeation chromatography, 1H- and 13C-NMR, 2D heteronuclear single quantum correlation (HSQC), and homonuclear 1H–2D double quantum filter correlation spectroscopy (DQF-COSY). Reactivity ratios for the copolymerization of V with E were calculated using the Kelen-Tudos (KT) and the nonlinear error in variables (EVM) methods. The reactivity ratios obtained from the EVM methods are rV = 0.80 ± 0.15 and rE = 0.87 ± 0.04. The microstructure was calculated in terms of the distribution of V- and E-centered triad sequences from 13C{1H}-NMR spectra of the copolymers. 2D HSQC was used to analyze the complex 1H-NMR spectrum and 2D COSY shows the various bond interactions, thus inferring the possible structure of the copolymers. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 417–426, 1998

Compositional Assignments and Sequence Distribution of Vinylidene Chloride−Methyl Acrylate Copolymers Using One- and Two-Dimensional NMR Spectroscopy

The microstructure of vinylidene chloride−methyl acrylate copolymers prepared by a photopolymerization process using uranyl ion as photosensitizer is analyzed by one- and two-dimensional NMR spectroscopy. Sequence distribution was calculated from 13C{1H} NMR spectra of the copolymers. A 13C distortionless enhancement by polarization transfer spectrum was used to differentiate between the resonance signals of methoxy and methylene units in the copolymer. Comonomer reactivity ratios were determined using Kelen−Tudos and the nonlinear error in variables methods. The sequence distribution of vinylidene chloride- and methyl acrylate-centered triads determined from 13C{1H} NMR spectra of copolymers is in good agreement with triad concentrations calculated from statistical model and Monte Carlo simulation methods. 2D heteronuclear single quantum correlation and correlated spectroscopy spectrum was used to analyze the complex 1H NMR spectrum.

Assignments of 1H And 13C NMR of 6(9)-Methyl-Benzo[b]naphthyridines (5-Methyldiazaanthracenes)

Abstract A complete assignment of the 1H and 13C NMR spectra of four 6(9)-methylbenzo[b]naphthyridines in CDCl3 is presented. The proton signals have been assigned from (1H-1H) coupling patterns and by the comparisons of chemical shifts with those of related heterocycles. Complete 13C assignments have been made using proton detected one bond (13C-1H) 2D heteronuclear single quantum correlation, the INEPT technique, and chemical shift comparisons with related heterocycles. The proton detected long range (13C-1H) 2D heteronuclear multiple quantum correlation experiment leads to an unambiguous assignment of the two quaternary carbons in 6-methyl-benzo [b][1,5] naphthyridine.