15 Creation of Molecularly Integrated Multi-responsive …
267
(a)
(b)
(c)
Fig. 15.9 Absorption spectral change of 18o–20o during 313-nm light irradiation in MeCN at 28
°C: a 18o (4.44 × 10 −5 mol dm −3 ), b 19o (4.38 × 10 −5 mol dm −3 ), c 20o (4.73 × 10 −5 mol dm −3 ).
Light intensity: 1.8 mW cm −2 . Reprinted from Ref. [36] by the Authors licensed under CC BY 4.0
(a)
(b)
(c)
Fig. 15.10 Absorption spectral change of 18c–20c kept at 28 °C in MeCN. Concentration of
compounds is the same as Fig. 15.9. a 18c. b 19c. c 20c. Reprinted from Ref. [36] by The Authors
licensed under CC BY 4.0
Table 15.2 Kinetic data of thermal back reactions of 18c-22c and aromatic stabilization energy of
their corresponding aromatic rings
A/s −1
E a /kJ mol −1
k (293 K)/s −1
t 1/2 (293 K) a
ASE b /kJ mol −1
21c c
7.1 × 10 11
112
6.7 × 10 −9e
3.3 years
72.9
22c c
1.3 × 10 9
85
8.7 × 10 −7e
9.2 days
78.6
18c d
1.54 × 10 13
87.4
4.18 × 10 −3
166 s
102.0
19c d
2.27 × 10 12
86.4
9.54 × 10 −4
727 s
102.0
20c d
3.88 × 10 13
82.2
8.99 × 10 −2
7.7 s
102.0
Reprinted from Ref. [36] by The Authors licensed under CC BY 4.0
a t 1/2 (293 K): Half-life at 293 K
b ASE: Aromatic stabilization energy of the central aromatic rings when unsubstituted. Data taken
from Ref. [42]
c In toluene. Data taken from Ref. [40] for 21 and Ref. [41] for 22
d In MeCN
e Calculated from t 1/2 at 293 K
The Arrhenius plots of ln k against 1/T gave preexponential factors A and Arrhenius
activation energies E a . The kinetic data of the thermal back reactions of 18c-20c are
shown in Table 15.2, together with literature data on related compounds 21c [40]
and 22c [41], as shown in Chart 15.9.