1
1
1
1
25.1, 125.3, 125.7, 125.9, 126.1, 126.3, 126.4, 126.4, 126.7,
26.7, 126.8, 126.8, 127.1, 127.1, 127.4, 127.5, 127.5, 127.6,
27.8, 128.7, 131.6, 132.3, 132.8, 135.3, 143.3, 143.3, 148.2,
48.3, 208.0.
the films nestled at the standard cell wall were recorded in the
ordinary transmittance mode.
Acknowledgements
Switching in solution
A sample of (R)-5a (14.2 mg, 2.2 ꢃ 10 mol) in d -benzene
This work was supported by the Slovak Research and
Development Agency (grant APVV-0128-07) and the Slovak
Grant Agency for Science (grant no. 1/0243/09).
ꢀ
5
6
ꢀ2
(
1.4 mL, 1.52 ꢃ 10 M) was placed into the NMR tube under
argon and irradiated at 313 nm for 5 min. Reversible switching
process was performed by heating of the sample at 84 1C in
water bath for appropriate time. For UV-vis measurements,
calculated volume of the sample was diluted with benzene to
c = 3.5 ꢃ 10ꢀ M. CD spectra of the whole samples were
recorded.
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5
A sample of (R)-5a (7.1 mg, 1.1 ꢃ 10 mol) in d
6
-benzene
ꢀ
2
(
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2
1
H NMR spectrum. The data corresponded to apparent first-
1
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ꢀ3
ꢀ1
1
2
0
min and a reaction half time t1/2 = 79.0 ꢂ 2.3 min at
7
6.5 1C.
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ꢀ
5
Three samples of (R)-5a (7.1 mg, 1.1 ꢃ 10
mol) in
ꢀ2
d
6
-benzene (0.7 mL, 1.52 ꢃ 10 M) were placed in tubes
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4
5
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mine the composition of the mixture. The found rate constants
ꢀ
3
ꢀ1
were: (0.89 ꢂ 0.11) ꢃ 10 min (14.0 1C), (3.73 ꢂ 0.41) ꢃ
ꢀ
3
ꢀ1
ꢀ3
ꢀ1
1
0
min (26.5 1C) and (7.30 ꢂ 0.66) ꢃ 10 min (35.0 1C).
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of the rate constant on reciprocal temperature as 74.5 ꢂ
7
8
9
ꢀ
1
5
.8 kJ mol .
Switching in polymer film
1
Films of poly(methyl methacrylate) (PMMA; Diacon, ICI,
England) and polystyrene (PS; Chemische Werke Huels,
F. R. G.) were prepared by casting a 1 mL chloroform solution
of the polymer (5 g/100 mL) containing the respective amount
of (R)-5a onto a glass plate (28 ꢃ 35 mm). The solvent
was evaporated slowly in the dark. The final concentration
1
1
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ꢀ1
of (R)-5a in the films was 0.02 mol kg . The thickness of the
films was 50 mm.
The photoisomerisation of (R)-5 was examined in thin
polymer films in a merry-go-round set up equipped with a
1
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1
25 W medium pressure mercury arc lamp and a chromate
2
7
liquid filter transmitting monochromatic light l = 313 nm.
Thermoisomerisation was performed in an oven at 70 1C for
an appropriate time. Electronic absorption and CD spectra of
1
15 W. Zhao and E. M. Carreira, US Pat. 2001/6281366, 2001.
1
114 | New J. Chem., 2010, 34, 1109–1115
This journal is ꢁc The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010