8 Red and Near-IR Fluorescent Two-Photon Absorption Dyes
287
N
N
S
N
N
S
N
N
N
800 GM at 780 nm, em 583 nm, F 0.70 (toluene)
3
N
S
N
N
N
2a: = none
2b: =
2c: =
2d: =
S
2e: =
2f: =
2a: 130 GM at 760 nm, em 592 nm, F 0.62 (toluene)
2b: 200 GM at 780 nm, em 550 nm, F 0.98 (toluene)
2c: 280 GM at 780 nm, em 661 nm, F 0.65 (toluene)
2d: 330 GM at 780 nm, em 617 nm, F 0.65 (toluene)
2e: 200 GM at 780 nm, em 568 nm, F 0.79 (toluene)
2f: 330 GM at 780 nm, em 654 nm, F 0.63 (toluene)
N
S N
N
π
π
π
π
π
π
π
π
δ
δ
δ
δ
δ
δ
λ
λ
λ
λ
λ
λ
Φ
Φ
Φ
Φ
Φ
Φ
δ
λ
Φ
Fig. 8.3 Benzothiadiazole-based red fluorescent TPA dyes 2a-f and 3
generation upon near-IR two-photon excitation (Fig. 8.4) (Ishi-i et al. 2007). The efficiency of two-photon-induced singlet oxygen generation was higher by two orders
of magnitude than that of tetraphenylporphyrin, indicating the excellent performance
N
N
H
N
H
N
Ar
Ar
Ar
Ar
N
S
N
N
N
4a: Ar =
4b: Ar =
441 GM at 800 nm, (
1 O 2 ) 0.68 (toluene)
735 GM at 800 nm, (
1 O 2 ) 0.65 (toluene)
N
S
N
Energy-transfer
Two-photon irradiation
ISC
Triplet state
3 O 2
1 O 2 *
Φ
Φ
δ
δ
Fig. 8.4 Singlet oxygen generation by two-photon excitation of the benzothiadiazole-porphyrin
TPA dyes 4a and 4b