2D-ROESY NMR

Combining 2D-NOESY and 2D-ROESY NMR experiments with molecular modelling protocols, Kuhn and Kunz32 have been able to study the saccharide-induced peptide conformational behaviour of the recognition region of Ll-Cadherin. The detailed conformational analysis of this key biomolecule not only proves that the saccharide side chain exerts a marked influence on the conformation of the peptide chain, but also that the size and type of the saccharide indeed strongly affects the conformation of the main chain. 

The detailed structure of the charge delocalised P-carotene dication (11) was established by COSY, HSQC, HMBC and ID and 2D ROESY NMR techniques (600 MHz, CDC13, -20°C), leading to complete... 

A series of 1-phosphonoalkylidene and 1-phosphonoarylidene nucleoside derivatives (88) and (89) have been obtained via a redox reaction of chlorodiethyl-phosphite with the corresponding nucleoside orthoesters. Yields are between 50 and 98% and in the case of (89) 2D ROESY NMR revealed the %-exo derivative to be the major product. 

Harada et al. [30, 31, 41] also have studied the supramolecular structure of 6-cinnamoyl a-CD in aqueous solution. The NMR and 2D ROESY NMR spectra of 6-cinnamoyl a-CD in various concentrations in D2O showed the formation of... 

Figure 3 shows the 600 MHz 2D ROESY NMR spectrum of dexamethasone. In this presentation, the... 

Fig. 9.4 The fixation of the Ala proton in cyclosporin A via ROE-derived distance restraints as an illustrative example for NMR structure determination. (A) The amide region of the 2D ROESY spectrum of cyclosporin A at room temperature with the cross-peaks to...

A complete NMR approach has been employed to evaluate the complexation process of catechin A with p-CD and synthetic analogues.125 The analysis of the variation of the proton chemical shifts indicated the formation of a 1 1 stoichiometric complex. 2D-ROESY provided detailed spatial information of the complex while the binding constants were obtained by using diffusion-order spectroscopy (DOSY) techniques. 

The x-CyD and /1-CyD ICs were analyzed using 111 NMR,14 including 2D ROESY 15 ICD 17 and microanalysis.133 The structures of the CyD ICs were concluded to be 45 (a-CyD)2 and (45 / -CyD)2. This denotes that diazirine 45 is sandwiched between two a-CyD units but that it forms a twofold 1 1 complex with /1-CyD.18 It has been demonstrated that a guest must have an electronegative group, like —F or —OH,15 18 to effect an opposite inclusion orientation within CyD in the... 

When supramolecular polymers are treated with bulky stopper groups, they may form poly[2]rotaxane daisy chains [45-53]. Harada et al. [31] treated 6-p-aminoCiO-a-CD (40 mM) with 2M excess 2,4,6-trinitrobenzenesulfonic acid sodium salt (TNBS) as bulky stoppers in aqueous solutions. The resulting precipitate was found to be mainly a cyclic trimer by H NMR and TOF mass spectra. After purification of the crude product, the 2D ROESY spectrum of the cyclic trimer shows cross-peaks between phenyl protons close to an amino group and secondary hydroxyl groups (0(2)H). A trinitrophenyl group is found at the secondary hydroxyl group side. A proposed structure of a cyclic trimer (cyclic daisy chain) is shown in Fig. 3.12. Kaneda et al. [38] reported the preparation of cyclic di[2]rota-xane fashion constructed tail-to-tail by azobenzene derivatives of permethylated a-CDs and showed its computer-generated supramolecular structures (Fig. 3.13). Easton et al. [39] also reported the preparation of cyclic di[2]rotaxane constructed by stilbene-appended a-CDs in tail-to-tail fashion (Fig. 3.14). Kaneda et al. [40]... 

The two frequency axes may consist of a diverse assortment of pairs of fundamental NMR parameters. Examples might include chemical shift on one axis and a frequency axis for scalar couplings on the second as in the 2D /-resolved NMR experiments. Both axes may be proton chemical shift, in which responses may be correlated by scalar (/) couphng as in the COSY experiment [46—48], by dipolar relaxation pathways as in the NOESY [35, 36, 49—51] and ROESY [35, 36, 52, 53] experiments, or by chemical exchange pathways as in the EXSY experiment [54—59]. Other examples may involve chemical shift on one axis and a multiple quantum frequency on the second axis. Examples here would include proton double [60 62] and zero quantum spectroscopy [63—67], C—INADEQUATE [68, 69], etc. The available axes in a 2D NMR experiment may also be used for hetero-nuclear chemical shift correlation, e.g. H—or H— N, where the respective nucHde pairs are correlated via their one-bond ( /xh) or multiple bond ("/xh) hetero-nuclear couphngs [14, 16, 17, 23—27, 29—31, 70—72]. 

Samples were prepared in 99.96% D O for NMR analysis. All the H NMR spectra were recorded with a Bruker Avance 400 MHz spectrometer operating at 300 K and were acquired with a spectral width of 5995.204 Hz, 128 scans and 65536 data-points. Both 2D COSY and ROESY experiments were acquired on a Bruker DRX 500 MHz using 5 mm BBI H-BB probe or a Varian Inova 500 MHz, equipped with a triple resonance, Z pulsed field gradient probe. 2D COSY spectra displaying H- H cross correlation for free FLZ, free P-CD and FLZ P-CD mixture were acquired using 2048 data-points with 128 increments and 18 scans for each increment. 2D ROESY spectrum of FLZ P-CD was acquired... 

D T-ROESY NMR spectroscopy performed for P-CD/m-TPPTC revealed strong correlation peaks between the ortho- and mefa-protons of phosphane with the inner protons H-3 and H-5 of CD, indicating a host-guest interaction between the CD cavity and phosphane. Physicochemical measurements indicate that CDs prefer adsorption at the aqueous/air interface, with their cavity perpendicularly oriented to the interface [13]. Both effects support substrate diffusion of the aqueous-supported... 

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