Double-quantum spectroscopy

On the whole, COSY is regarded as a more reliable and simple experiment, although double-quantum spectroscopy is used in some special circumstances. 

A simple sequence for double quantum spectroscopy is shown below... 

ADEQUATE Adequate sensitivity double-quantum spectroscopy 5.9... 

There are probably, at present, about four homonuclear 2D NMR experiments in common usage for small molecules. These include COSY (Correlated SpectrospY) [46-48], TOCSY (TOtal Correlation SpectroscopY) [77-79], NOESY [35, 36, 49—51], and ROESY [35, 36, 52, 53], the latter two corresponding to nuclear Over-hauser and spin-locked Overhauser correlated experiments, respectively. Several less frequently employed homonuclear 2D experiments are also possible and include C— C [68, 69] double quantum spectroscopy [60—62] zero quantum spectroscopy [63—67], and others H. We will discuss the primary experiments in the category briefly in turn, and we will direct the reader interested in other homonuclear 2D variants to the appropriate literature. 

The most commonly used 2D nmr technique applied to through-bond interactions is termed (7 ) correlated spectroscopy (COSY), others are total correlation spectroscopy (TOCSY), which allows somewhat longer-range through-bond connectivities to be observed than with COSY, spin echo coherence transfer spectroscopy (SECSY), relayed coherence transfer spectroscopy (RELAY), double quantum spectroscopy (DQNMR) and homonuclear Hartmann-Hahn spectroscopy (HOHAHA). The most commonly used 2D nmr technique applied to through-space interactions is termed nuclear Overhauser effect spectroscopy (NOESY) also used is the closely related rotating-frame NOESY (ROE-SY). 

These multiple pulse methods are summarized in Table 3. Examples are the use of SPT for N and C, and D in a liquid crystal solvent SPI for quaternary carbon double SPT for Si, C, and N satellites in C spectra INEPT with double quantum spectroscopy for Ag and Rh pulse-interrupted precession for N INEPT with delay for Si and Sn INEPT using polarization transfer from P to M = Rh, W, and Fe, and JCP for N in polymers. ... 

Figure 1. Pulse sequences of some typical 2D-NMR experiments. COSY = correlation SpectroscopY, DQFCOSY = Double Quantum Filtered COSY, RELAY = RELAYed Magnetization Spectroscopy, and NOESY = Nuclear Overhauser Effect SpectroscopY.

Figure 1.45 Coherence transfer pathways in 2D NMR experiments. (A) Pathways in homonuclear 2D correlation spectroscopy. The first 90° pulse excites singlequantum coherence of order p= . The second mixing pulse of angle /3 converts the coherence into detectable magnetization (p= —1). (Bra) Coherence transfer pathways in NOESY/2D exchange spectroscopy (B b) relayed COSY (B c) doublequantum spectroscopy (B d) 2D COSY with double-quantum filter (t = 0). The pathways shown in (B a,b, and d) involve a fixed mixing interval (t ). (Reprinted from G. Bodenhausen et al, J. Magn. Resonance, 58, 370, copyright 1984, Rights and Permission Department, Academic Press Inc., 6277 Sea Harbor Drive, Orlando, Florida 32887.)...

Zheng et al. [1] postulated that the driving force for placing Zr and B on the same carbon might stem from interactions between the zirconium and oxygen or boron and chlorine atoms. However, an X-ray analysis of 22 revealed that there are no intra- or intermo-lecular interactions between any of these atoms [35]. Compound 22 was also unambiguously characterized by 1H-1H double quantum filtered COSY [36] and 13C-1H heteronuc-lear chemical shift correlation NMR spectroscopy [37,38]. Considerable differences in the chemical shifts of the diastereotopic Cp groups were found in both the XH and 13C NMR spectra. The NMR study unequivocally showed that the methine proton was at-... 

Sowinski and coworkers40 reported a structure of vacidin A (63), an aromatic hep-taene macrolide antibiotic. The constitution of vacidin A, a representative of the aromatic heptaene macrolide antibiotics, was established on the basis of 13C and H- H double quantum filtered correlated spectroscopy, rotating frame nuclear Overhauser effect spectroscopy, 7-resolved 11 as well as H-13C correlation NMR spectra. The geometry of the polyene chromophore was determined as 22E, 24E, 26E, 28Z, 30Z, 32E, 34E. 

The data from H NMR studies of 63, which included double quantum filtered phase sensitive correlated spectroscopy (DQF-COSY) and rotating frame nuclear Overhauser effect spectroscopy (ROESY) experiments (Figure 12), are collected in Table 17. 

These results suggest that the signals arise from dipole-dipole coupled protons. Kreis et al. confirmed this finding by measurements using one-dimensional zero- and double-quantum filtering, two-dimensional J-resolved spectroscopy, two-dimensional constant time COSY and longitudinal order separation... 

R.P. Mason, G. Cha, G.H. Gorrie, E.E. Babcock, P.P. Antich, Glutathione in whole blood A novel determination using double quantum coherence transfer proton NMR spectroscopy, FEBS Lett. 318 (1993) 30-34. 

K. Yamanouchi Recently, we investigated the interatomic potential VRyd(/ ) of the Rydberg states of a HgNe van der Waals dimer by optical-optical double-resonance spectroscopy. It was demonstrated that VRyd(/ ) sensitively varies as a function of the principal quantum number n [J. Chem. Phys., 98, 2675 (1993) ibid., 101, 7290 (1995) ibid., 102, 1129 (1995)], and in the lowest Rydberg states of Hg(7 3S )Ne and Hg(7 5o)Ne, the interatomic potentials exhibit a distinct barrier at around R 4 A. The existence of the barrier was interpreted in terms of a repulsive interaction caused by the Is Rydberg... 

Record the 2-D H- H double quantum filtered correlation spectroscopy (DQF-COSY) spectrum (Braun et al., 1998, pp. 481-484). 

NMR spectroscopy was carried out using a Varian Unity 300MHz spectrometer. Peptides were dissolved in 500 pL of 90% H,O/10% D20 (or 100% D20) giving a sample concentration of 1-2 mM and the pH adjusted to 5.5. H DQF-COSY (double quantum filtered two-dimensional correlated spectroscopy), ROESY, and TOCSY spectra were collected at 25 °C and processed as described.1 6-281... 

On the other hand, the digermirane (18) reacts with Cgo to afford the 1,4-adduct (19, twist form) selectively15. The structure of the 1,4-adduct was confirmed by 13C-13C INADEQUATE (Incredible Natural Abundance Double Quantum Experiment) spectroscopy (equation 5). The rate of disappearance of Cgo was suppressed by addition of diazabicyclo[2.2.2]octane and 1,2,4,5-tetramethoxybenzene. Furthermore, the reaction was completely inhibited by addition of rubrene as triplet quencher. One plausible rationale for these observations is that an exciplex intermediate may be responsible for formation of the products (Scheme 6). 

In several kinds of correlation spectroscopy it is customary to also exploit the evolution of either zero quantum (ZQ) or double quantum (DQ) coherences. As shown in Fig. 7.1, they correspond to the transition — + + — and... 

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