Poly cosy spectrum

Two-dimensional (2D) NMR spectroscopy has recently been used to make absolute tacticity assignments without any other supports.195-208 An early successful example is H COSY analysis of poly(vinyl alcohol).198,199 Figure 17 shows a broad-band decoupled H COSY spectrum of poly (vinyl alcohol)199 and illustrative assignments for the correlations between triad peaks of methine proton and tetrad peaks of methylene protons. Expected connectivities between triad and tetrad are as follows ... 

Stereochemical assignments have also been made at the pentad level for poly (vinyl fluoride) from the 19F COSY spectrum, in which the cross-peaks arise from four-bond scalar coupling (about 7 Hz) between the central pair of fluorines in the pentad sequences that share a common hexad.200... 

Figure 1.25 (a) The broadband decoupled COSY spectrum of poly(vinyl alcohol) under the same conditions as Figure 1.24 (b) expansions of the CH diagonal peaks and the CH/CH2 correlation peaks (c) schematic representation of the correlation peaks, with assignments given in Table 1.5. Reprinted with permission from [64]. 

Table 1.5 Assignment of the correlation peaks in the broadband decoupled COSY spectrum of poly(vinyl alcohol) in Figure 1.25 (from [64])...

Figure 6 COSY. spectrum of Poly(vinyl alcohol) in DMSO-d,...

Figures 13.7 and 13.8 are two examples of two-dimensional NMR spectroscopy applied to polymers. Figure 13.7 is the proton homonuclear correlated spectroscopy (COSY) contour plot of Allied 8207A poly(amide) 6 [29]. In this experiment, the normal NMR spectrum is along the diagonal. Whenever a cross peak occurs, it is indicative of protons that are three bonds apart. Consequently, the backbone methylenes of this particular polymer can be traced through their J-coupling. Figure 13.8 is the proton-carbon correlated (HETCOR) contour plot of Nylon 6 [29]. This experiment permits the mapping of the proton resonances into the carbon-13 resonances.

Figure 24.13a shows the ID-NMR spectra of the poly(tetrafluoroethylene-co-propylene) poly(TFE-P) the complex peak patterns were mainly attributed to couplings which made peak assignment difficult. They obtained a F J-resolved (Figure 24.14) and F COSY (Figure 24.15) 2D-NMR spectra which helped with the assignments. In the J-resolved 2D-NMR spectrum, if the data are skewed about the /i =0 axis by 45° in frequency space, a spectrum with pure F chemical shift in the/2 dimension and pure Tpp coupling in the/i dimension is obtained. A projection of this 2D-NMR spectrum onto the/2 axis produces a pure chemical shift spectrum (with homonuclear couplings removed). This broadband homonuclear decoupled spectmm is shown across the top of the 2D-NMR plot in Figure 24.14, and is reproduced in Figure 24.13b below the normal F ID-NMR spectrum. The F broadband homonuclear decoupled spectmm shows eight resolved peaks numbered from 1 to 8 (-110.3(1), -112.6(2), -113.1(3), -115.2(4), -116.0(5),...

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