2D-COSY spectrum

Load the phase sensitive 2D COSY spectrum of peracetylated glucose... 

Try out the effect of several modes for DC correction available with 2D data. Load the raw data of the magnitude mode 2D COSY spectrum D NMRDATA GLUCOSE 2D HH GHHCO 001001.SER and choose no, quad and qpol as BC mod in F2. Note that usually for Fl no baseline correction is applied in the time-domain, i.e. BC mod (F1) = no. Fourier transform the data and store the individual spectra using ascending processing numbers. Compare corresponding rows to inspect the effect of different baseline corrections. 

NOES Y, a 2D COSY spectrum showing NOE interactions to, angular frequency (rad s l)... 

Spin pinging [5.86] has been proposed as a method of using rectangular pulses in 2D homonuclear COSY experiments for tailored excitation. Using spin pinging it would be possible to select regions of overlapping multiplets which are not defined sufficiently in a standard 2D COSY spectrum because of the restricted number of data points. Probably... 

Figure 5.1. A stacked plot of the 2D COSY spectrum of thebaine in CDCl at 400 MHz. The aliphatic region only is shown. The original spectrum had a frequency width of 2100 Hz in f/ and f and, after zero-filling once in f , a final matrix size 1024 x 512 which gave a resolution of 4.1 Hz per point in each direction. A sinebell window function was applied and the spectrum has been symmetrized. 128 scans...

Figure 5.2. A contour plot for the same region of the 2D COSY spectrum of thebaine as shown in Figure 5.1. This spectrum allows interconnections to be established between all groups of coupled signals (see partial formula), for example a (9-H) to d(10 cc-H), b(Wp-H) to d(lOa-H), d to a and b c(axial 16-H) to g(equatorial 15-H),f(axial 15-H) and e(equatorial 16-H). Connecting lines are drawn to show this last set. Resonances d and e overlap.

Figure 3.50 A small portion of an actual 2D-COSY spectrum of a glucopyranoside. This is an expansion of the region from 3.6 to 5.6 ppm. (Modified from Bruch, used with permission.)...

D COSY spectrum indicated the larger doublet at S7.25 (8.1 Hz) was due to vicinal coupling of F—H while the smaller coupling (2.3 Hz) was the result of H2—H6 meta coupling... 

Fig. 9.6. Two-dimensional (2D) COSY spectrum ofa-CyD in D2O. Off-diagonal cross peaks allow us to follow the spin-spin coupling network and assign subsequent signals starting at the anomeric H-1 proton characteristic of its large chemical shift.

As an example. Figure 5 shows a COSY pulse sequence (Figure 5A) and the 2D COSY spectrum of heptan-3-one with the ID spectrum plotted across the top (Figure 5B). The 2D spectrum contains a series of peaks along the diagonal whose positions in /"i and fi correspond to the positions of the peaks in the ID spectrum. Off the diagonal, cross peaks exist which correlate the frequencies of proton pairs which are coupled to each other. In COSY... 

Figure 3 H- H 2D COSY spectrum of galactopyrarwse p 1 -4glucopyrarK>se at 500 MHz and 303 K in 2H2O. Afull proton assignment is usually possible from a spectrum like this, and peak identities are shown where space permits. The well-resolved anomeric protons provide a useful starting point for assignment, and subsequent pairs of spin-coupled nuclei are correlated through off-diagonal peaks.

The spectra of polyglucuronic acid grafted amines were analyzed and the different proton signals assigned by 2D-COSY (spectrum not presented) and 2D HMQC... 

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