2D J-resolved spectrum

Figure 2.6 2D J-resolved solid-state NMR spectrum of Hf( CH2Bu )3/Si02 (soo) (a) and of Zr("CH2Bu )3/Si02-(8oo) (b) trace extracted along the tB dimension of the 2D J-resolved spectrum at S = 106 and 93 ppm, respectively.

In the J-resolved projection, the aromatic rings of the SCAL are clearly present where as the polymer resonances have dropped out of the spectrum. In addition, the proton coupling constants arising from alloc group are readily measured as seen in the expanded spectrum (Fig. 13). If a more detailed measure of the couplings is desired, then the full 2D J-resolved spectrum can be evaluated in the normal manner as exemplified in Fig. 14. A similar method to obtain accurate proton-proton coupling constants based on E.COSY spectra has also appeared recently (43). 

Figure 12 400 MHz MAS HNMR spectrum for Alloc-Asp-derivatized oxazolidi-none on SCAL-linked aminomethylpolystyrene. (a) Spin-echo HNMR spectrum, (b) Nontilted projection from 2D J-resolved spectrum.

Figure 13.3-2. NMR spectra of rat serum illustrating the various NMR responses that are possible through the use of different pulse sequences, which edit the spectral intensities (a) standard water suppressed spectrum, showing all metabolites (b) CPMG spin-echo spectrum, with attenuation of peaks from fast relaxing components such as macromolecules and lipoproteins (c) diffusion-edited spectrum, with attenuation of peaks from fast diffusing components such as small molecules and (d) a projection of a 2D J-resolved spectrum on to the chemical shift axis, showing removal of all spin-spin coupling and peaks from fast relaxing species.

Figure 2. 2D J-resolved proton spectrum of the protein bovine pancreatic trypsin inhibitor (BPTI). a. High-field region from 0.4—1.6 ppm, which contains the resonances of 19 methyl groups of the 360-MHz H NMR spectra of a 0.01 M solution of BPTI in D O at pH 4.5, 60°C. Prior to the Fourier transformation, the 2D data set was weighted in the t, and ts directions by weighting functions cos[(t.J 2Tx)ir]exp(tx/0.4Tx), with x = 1,2 Tj = 2.46 s, and Ts = 1.23 s are the maximum acquisition times in the ti and tj domains. The 2D J-resolved spectrum was computed from 64 X SI 92 data points and is presented as a (J, spectrum the top trace shows the conventional ID spectrum the bottom trace shows the projection of the 2D spectrum with 4> = rtl4. b. Presentation of the 2D J-resolved H spectrum (a) by cross sections. The resolved multiplets of 19 methyl protons are shown. The 2D resolved spectrum allows the analysis of otherwise overlapping multiplets, the accurate measurement of coupling constants, and the assignment of the resonances. (Reproduced, with permission, from Ref. 14. Copyright 1978, Academic...

Figure 3 A 3ip 3ip homonuclear 2D J-resolved NMR spectrum of a dissolved sodium phosphate glass with n = 4.1 (shown at the bottom). The characteristic J-coupling for each species is observed, causing extensive overlap in the corresponding 1D spectrum shown at the top. The vast simplification obtained by projecting the 2D J-resolved spectrum vertically onto the chemical shift axis (middle spectrum) clearly delineates the effectively broadband decoupled resonances. All spectra were accumulated at 161.9MHz using a 5% (m/m) phosphate solution in H2O with a D2O insert for locking purposes.

Figure 5.42. (i) Normal ID proton-coupled C-spectrum of 5a-androstane. (ii) ID proton-decoupled spectrum of 5a-androstane. (iii) Stacked trace plot of 2D J-resolved spectrum of 5a-androstane obtained with gated decoupler sequence, (iv) Contour plot of 2D J-resolved spectrum of 5a-androstane obtained with gated decoupler sequence. 

Figure 5.49. (A) Homonuclear 2D J-resolved spectrum of the vinyl protons of vinyl acetate. (B) Projection at 45° to the coi axis yields a proton-decoupled spectrum. (C) Projection in the a>i direction (i.e., vertically) results in a proton-coupled spectrum.

Fig. 10.13. 2D J-resolved NMR spectrum of santonin (4). The data were acquired using the pulse sequence shown in Fig. 10.12. Chemical shifts are sorted along the F2 axis with heteronuclear coupling constant information displayed orthogonally in F . Coupling constants are scaled as J/2, since they evolve only during the second half of the evolution period, t /2. 13C signals are amplitude modulated during the evolution period as opposed to being phase modulated as in other 13C-detected heteronuclear shift correlation experiments.

Fig. 3.27 2D spectrum (tilted) of peracetylated glucose from a homonuclear 2D J-Resolved experiment. 

The pulse methods rely on selective irradiation of a particular resonance line with a radio frequency (rf) and observation of the resulting effects in the rest of the spectrum. Among commonly employed methods are 2D correlated spectroscopy (COSY), 2D spin-echo correlated spectroscopy (SECSY), 2D nuclear Overhauser and exchange spectroscopy (NOESY), 2D J-resolved spectroscopy (2D-J), and relayed coherence-transfer spectroscopy (RELAYED-COSY) (Wutrich, 1986). 

The pulse sequence, as a variant of the spin echo experiment, also refocuses the spread of frequencies caused by field inhomogeneity, so that some improvement in resolution is obtained. The inset at the lower right of Figure 6-18 shows the normal ID spectra of H-4 and H-5 at the top (Figure 6-18c and e) and the unrotated projection of the 2D J-resolved spectra at the bottom [Figure 6-18d and f, extracted from the projected spectrum (Figure 6-18a) at the top of the 2D display]. The much higher resolution of the 2D resonances is clearly evident. Thus, the procedure is an effective way to measure J accurately, particularly when J is poorly resolved in the ID spectrum. The experiment fails for closely coupled nuclei (second-order spectra). 

Figure 6-18 The 270 MHz 2D 7-resolved spectrum of 2,3,4,6-tetrakis-O-trideuleroacetyl-a-D-glucopy-ranoside. (Reproduced from L. D. Hall, S. Sukumar, and G. R. Sullivan, J. Chem. Soc., Chem. Commun., 292 [1979]).

Figure 10 Schematic representation of nontilted 2D J-resolved experiment. Projection onto the chemical shift axis recovers the high resolution ID NMR spectrum.

Figure 14 Partial 2D J-resolved NMR spectrum for Alloc-Asp-derivatized oxazoli-dinone attached via its side chain carboxyl to SCAL-linked aminomethylpolystyrene swollen with DMF-d7.

Fig. (7). 2D J-resolved NMR spectrum of cammeliatannin D (67) (500 MHz, acetone-

In such a situation, an extension to 2D spectroscopy Is In order. A 2D spectrum S(co, U2) Is capable of representing simultaneously two Independent features without leading to any ambiguity, for example representing multlplet splittings along u). which are shifted by the pertinent chemical shifts in the uip direction. Such a representation Is realized in 2D J-resolved proton spectroscopy (1). 

Fig. 8.9 Contour plot of the amplitude modulated 2D J-resolved NMR spectrum of the simple alkaloid santonin (1) recorded at 400 MHz. The reference spectrum is plotted along the horizontal axis the so-called J-spectrum ...

Figure 3.5 Partial 2D J-resolved H NMR spectrum of poly(acrylonitrile) in DMSO-dg. The multiplets are effectively rotated into the vertical dimension. The large peak at 3.06 ppm arises from water, and the uneven ridge marked x is partly an artefact...

Figure 5.50. Homonuclear 2D J-resolved H spectrum of ethanol in the methylene region. Above Stacked plot (left) and contour plot (right). Below Stacked plot (left) and contour plot (right) after 45° rotation.

Fig. 6.29. Expansion of the 500-MHz 2D 7-resolved spectrum of the methyl region of atactie polyfpropylene oxide). The circled numbers correspond to the five main doublets. The splittings due to the J coupling can be observed in the upper and lower portions of the figure. The measured 7ch3-ch value of 6.5 Hz corresponds to the expected value for this system. (Reproduced from Ref. [71]. 1985 American Chemical Society.)...

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