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Fig. 15.3 Shift of absorption band of 3c in the 550–800 nm range by the photochromic reaction
between 2mc and 2sp in chloroform. a Irradiation of 450-nm light to induce the change from 2mc
to 2sp. b Thermal reaction to induce the change from 2sp to 2mc at r.t. (ca. 20 °C). Concentration:
3c 2.40 × 10 −5 mol dm −3 , 2mc 3.84 × 10 −4 mol dm −3 (16 eq). From [9] Copyright © 2016 by
Wiley, Inc. Reprinted by permission of Wiley, Inc.
Fig. 15.4 Four states of the 3-and-2 system generated by light irradiation and thermal treatment
in chloroform. a 3c and 2mc, dark green; b 3c and 2sp, dark cyan, 450-nm light irradiation of (a);
c 3o and 2mc, orange, generated by 640-nm light irradiation of (a); d 3o and 2sp, faint yellow,
generated by 450-nm light irradiation of (c). Other conversion methods are described in the figure.
Concentration: 3 1.2 × 10 −4 mol dm −3 , 2 4.8 × 10 −4 mol dm −3 . Optical path length: Spectra
2 mm, photographs 20 mm. From [9] Copyright © 2016 by Wiley, Inc. Reprinted by permission of
Wiley, Inc.