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AcO
O
1
)
a −
CD, AcOK
N
N
2) NH
4
PF
6
I
N
PF
6
5
− a
-CD-PF
6
Fig. 4 Synthesis of cyanine dye rotaxane 5
a
-CD
PF
6
N
N
Cl
O
R
2
n
n
N
6a, 6b
R
1
a
-CD
R
2
Cl
R
2
R
2
NaOH / H
2
O
N
R
1
N
Cl
R
2
n
N
a
-CD
7a, 7b
R
1
R
2
-CD
a
N
Cl
R
2
n
N
8a, 8b
R
1
n = 1, R
1
= adamantyl, R
2
= H (
a
)
n = 2, R
1
= Me, R
2
= Ph (
b
)
R
2
Fig. 5 Synthesis of
a
-CD-based styryl-rotaxanes 6a, b and 7a, b [
4
,
27
]
10
5
M
1
cm
1
) and the
of 5
a
-CD
PF
6
in methanol is 770 nm (
e
M
¼
2.8
emission maximum is 796 nm (
F
F
¼
0.23), whereas the free dye 5 absorbs at
10
5
M
1
cm
1
) and emits at 778 nm (
741 nm (
0.37) [
26
].
Encapsulation of the cyanine dye 5 reduces the fluorescence quantum yield but
increases its photostability (3.9-fold), and chemical stability.
Reaction of 3-(9-julolidinyl)prop-2-en-1-al with
N
-(1-adamantyl)-4-methyl-pyr-
idinium chloride and
e
M
¼
2.3
F
F
¼
-CD in aqueous sodium hydroxide yielded
styryl
dye
rotaxanes 6a and 7a as well as the free dye 8a (Fig.
5
)[
4
,
27
]. Analogously, the
two rotaxane isomers 6b and 7b, and the free dye 8b were obtained from julolidine
aldehyde and 4-methyl-2,6-diphenylpyridinium chloride. As compared to the
hydrophobic dyes 8a, 8b, the rotaxanes 6a, 6b and 7a, 7b are highly soluble in
water. The absorption/emission maxima of the rotaxanes 6a (525/710 nm) and
7a (535/718 nm) in DMSO are red-shifted compared to free styryl dye 8a
a
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