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SCHEME 8.2
Functionalization of DAB-based dendrimers with amidoferrocenyl aza-crown
ethers.
proton at 8.43 ppm (Figure 8.10a). In the presence of 2 equiv. of fluoride anion a
significant downfield shift (
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(Figure 8.10b) that is consistent with the hydrogen-bonding interaction between the
fluoride anion and the amide group. On the other hand, in the presence of 2 equiv. of
KPF
6
, the NH resonance of
Dd ¼
0.59) was observed for the amide NH protons of
is slightly upfield shifted to 8.31 ppm (Figure 8.10c)
because cation complexation prevents hydrogen bonding between the amide proton
and the oxygen atoms of the aza-crown ether. Finally, upon addition of 2 equiv. of
TBAF to this solution, the NH resonance is very slightly downfield shifted again to
8.36 ppm (Figure 8.10d). From these results it was concluded that the presence of K
þ
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