Suspended cross-peaks

Figure 36 illustrates the 2D spectra measured after feeding vinorine (17) to suspended cells for 7 h. During that period, the vinorine concentration decreased remarkably and the major alkaloid became vellosimine indicating that deacetylation of vinorine (17) took place and the product was further transformed into vellosimine (16). A cell sample measured after 24 h, showed that most of vinorine had disappeared already and that the first cross peaks showed up for vomilenine (29) and/or raucaffncine (30) (see Figure 36(a) and (b)). 

Table 1. Comparison of trNOE cross-peaks obtained from suspended-state H R/MAS NMR experiments on analytes 6 and 7 in the presence phases A and B suspended in [D4 methanol (80%) and DjO.

Fig. 9. Suspended-state HR/MAS trNOESY spectrum of (S)-8 dissolved in CDCI3 in the presence of Kromasii-DMB showing both intramolecular cross-peaks (black) and intermolecular cross-peaks (grey).

Several difFerent suspended-state HR/MAS NMR experiments can be performed in order to obtain information aboutly exact where the interactions take place between an analyte and a sorbent. In Fig. 9, the suspended-state HR/MAS trNOESY spectrum of (S)-8 dissolved in CDCI3 in the presence of Kromasil-DMB, shown in Fig. 5, shows both negative intramolecular trNOE cross-peaks (black), confirming the interaction with the sorbent, and intermolecular (grey) cross-peaks between the aromatic residue in the selector and the aromatic ring in the analyte... 

FIGURE 3.6. (a) Cross-sectional schematics of a silicon wafer with a nanopore etched through a suspended silicon nitride membrance. SAM is formed between sandwiched Au eletrodes in the pore area (circled), (b) I(V) characteristics of a Au-2 -amino-4-ethynylphenyl-4-ethynylphenyl-5 -nitro-1 -benzenethiolate-Au (chemical structure shown below) molecular junction device at 60 K. The peak current density is 50 A/cm2, the NDR is 2400 pQ. cm2, the peak-to-valley ratio is 1030 1. [Adapted from Ref.30 Chen el al., Science 286, 1550-1552 (1999).]... 

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