Chemistry Reference
In-Depth Information
Table 5 Photophysical characteristics of squaraine dyes, squaraine rotaxanes, and IgG conjugates [
60
]
Dye
l
max
Ab
(nm)
l
max
Em
(nm)
F
F
t
mean
(ns)
Solvent
21a
Chloroform
634
652
-
-
21a
Rp
Chloroform
645
660
0.70
2.45
21e
Water
644
670
0.03
0.05
21e
Rp
Water
655
673
0.25
0.90
21e
Rp-IgG
(
D
/
P ¼
1)
Water
657
675
0.31
1.83
2.60
a
22a
DMF-water (1:2)
645
664
0.29
2.79
a
22a
Rp
DMF-water (1:2)
642
659
0.35
22b
Water
638
654
0.25
1.56
22b
Rp
Water
640
656
0.40
2.40
22c
Chloroform
681
697
0.58
-
22c
Rp
Chloroform
676
690
0.59
-
22d
Chloroform
681
698
0.57
3.36
22d
Rp
Chloroform
661
674
0.66
3.52
22e
Water
638
655
0.31
1.73
22e
Rp
Water
642
658
-
2.45
a
Chloroform
a
b
1.0
1.0
21e
⊂
Rp-IgG
22b
⊂
Rp
0.8
0.8
21e
⊂
Rp
0.6
0.6
Cy5
0.4
0.4
21e
0.2
0.2
22b
0.0
0.0
0
50
100
150
200
0
50
100
150
200
Time [min]
Time [min]
Fig. 9 Comparison of the photostability (decrease of fluorescence intensity upon exposure to
light of a 200 W Xenon lamp) of 21e, 21e
Rp, and 21e
Rp-IgG conjugate (a) and 22b,
22b
Rp, and Cy5 (b) in aqueous buffer [
60
]
pseudorotaxanes 24a
23a and 24b
23a. Relevant spectral data of 24a
23a
and 24b
23a are shown in Table
6
in comparison to squaraine 23a. Both the
absorption and emission show red shifts, which are similar to those of the anili-
ne-squaraine rotaxanes with phenylene- and anthrylene-based macrocycles [
52
,
53
,
55
,
56
,
58
]. Compared to the free squaraine 23a, the fluorescence quantum yields of
the pseudorotaxanes are reduced. Rotaxane 24b
23a shows a higher quantum
yield than rotaxane 24a
23a. The association constants between the hosts and the
guest in chloroform were determined to be 6.8
10
5
M
1
0.3
for 24a
23a
10
6
M
1
and 1.3
23a, respectively, which indicates that the
macrocycles 24a and 24b are excellent hosts for the squaraine dye in a weakly polar
solvent.
0.3
for 24b
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