1 Polymethine Dyes
17
Fig. 1.12 Liquid trimethine
dyes
(C 4 F 9 SO 2 ) 2 N
N
X
R
X
N
R
X
C(CH 3 ) 2
S
O
R
C 12 H 25
(CH 2 CH 2 O) 3 CH 3
(CH 2 CH 2 O) 3 CH 3
T g /
o
C
_ 18
_ 23
_ 22
1.62
1.3.4 Fluorescence of Polymethine Dyes
Polymethine dyes are fluorescent in solution. Many polymethine dyes have been used
as probes. Recently, the fluorescence quantum yield ( f ) of pentamethine dye was
improved by annelating the linkage group. The f of 1.64 and 1.65 were measured
to be 0.69 and 0.55, respectively, whereas that of 1.63 was 0.15 (Michie et al. 2017)
as shown in Fig. 1.13.
Though most polymethine dyes are fluorescent in solution, the fluorescence intensity decreases in the crystalline form. In the case of indolenium trimethine dyes 1.66,
the dipropyl derivative having a bis(trifluoromethylsulfonyl)imide anion exhibited
the highest f in the crystalline form as indicated in Fig. 1.14. The X-ray structure
max
638
662
670
b
R
λ
λ
ε
Φ
τ
1.63
a
1.64
a
1.65
f
0.15
0.69
0.55
b
N
N
H 3 C
CH 3
CH 3
H 3 C
CH 3
CH 3
N
N
H 3 C
CH 3
CH 3
H 3 C
O
H
H
H
R
1
R
2
1.63
1.64: R
1 = R
2 = H
1.65: R
1 = SO 3
- , R
2 = COOH
214,000
206,000
199,000
b
em
657
677
683
b
/ ns
0.7
2.5
1.7
c
Fig. 1.13 Enhancement of fluorescence intensity of pentamethine dye. a In methanol, b in pH 7.4
PBS, c in H 2 O
17
Fig. 1.12 Liquid trimethine
dyes
(C 4 F 9 SO 2 ) 2 N
N
X
R
X
N
R
X
C(CH 3 ) 2
S
O
R
C 12 H 25
(CH 2 CH 2 O) 3 CH 3
(CH 2 CH 2 O) 3 CH 3
T g /
o
C
_ 18
_ 23
_ 22
1.62
1.3.4 Fluorescence of Polymethine Dyes
Polymethine dyes are fluorescent in solution. Many polymethine dyes have been used
as probes. Recently, the fluorescence quantum yield ( f ) of pentamethine dye was
improved by annelating the linkage group. The f of 1.64 and 1.65 were measured
to be 0.69 and 0.55, respectively, whereas that of 1.63 was 0.15 (Michie et al. 2017)
as shown in Fig. 1.13.
Though most polymethine dyes are fluorescent in solution, the fluorescence intensity decreases in the crystalline form. In the case of indolenium trimethine dyes 1.66,
the dipropyl derivative having a bis(trifluoromethylsulfonyl)imide anion exhibited
the highest f in the crystalline form as indicated in Fig. 1.14. The X-ray structure
max
638
662
670
b
R
λ
λ
ε
Φ
τ
1.63
a
1.64
a
1.65
f
0.15
0.69
0.55
b
N
N
H 3 C
CH 3
CH 3
H 3 C
CH 3
CH 3
N
N
H 3 C
CH 3
CH 3
H 3 C
O
H
H
H
R
1
R
2
1.63
1.64: R
1 = R
2 = H
1.65: R
1 = SO 3
- , R
2 = COOH
214,000
206,000
199,000
b
em
657
677
683
b
/ ns
0.7
2.5
1.7
c
Fig. 1.13 Enhancement of fluorescence intensity of pentamethine dye. a In methanol, b in pH 7.4
PBS, c in H 2 O