Communication
2 were recorded on a Xevo G2 QT mass spectrometer by using
methanol as solvent, whereas the ESI-MS spectrum of compound 3
was recorded on a Bruker APEX IV FTMS in negative mode by
using MeCN as solvent. Fourier transform infrared (FTIR) spectra
were recorded on a Bruker Vector 22 infrared spectrometer using
the KBr pellet method; intensities donated as vs=very strong, s=
strong, m=medium, w=weak, and vw=very weak. UV/Vis ab-
sorption analysis was recorded on a TU-1901 double-beam ultra-
violet–visible spectrophotometer. Elemental Analyses were com-
pleted by using a VarioEL cube from Elementar Analysensysteme
GmbH. The average molecular weight and the polydispersity analy-
ses were carried by gel-penetration chromatography (GPC, Agilent
2600 series).
Ethyl 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy) acetate[20] (1) and N-
(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-2-((4-methyl-2-oxo-
2H-chromen-7-yl)oxy)acetamide[5f] (2, denoted as Coumarin-Tris)
were prepared according to literature methods.
Figure 7. a) The color change of film samples; b) fluorescence spectra before
(black) and after (grey) irradiation for 90 min; c) reversible fluorescence re-
sponse over five consecutive cycles of 365 nm and 254 nm irradiation.
Synthesis of [(TBA)3(MnMo6O18-
{(OCH2)3CNHC12H9O4}2)]·2DMF·0.5H2O (3)
A
mixture of TBA4[a-Mo8O26] (2.00 g, 0.93 mmol), Mn-
(CH3COO)3·2H2O (0.37 g, 1.4 mmol), and (HOCH2)3CNHC12H9O4 (2)
(1.08 g, 3.2 mmol) in acetonitrile (50 mL) was heated at reflux for
24 h. The orange solution was cooled to room temperature and
then exposed to diethyl ether vapor for two weeks. The orange
precipitate was filtered and then dissolved in a mixture of MeCN/
DMF (1:1). Small orange crystals can be obtained after three weeks.
Yield 2.26 g (79%, based on TBA4[a-Mo8O26]). 1H NMR (400 MHz,
[D6]DMSO) d=7.96 (s, 2H), 7.74 (d, J=6.33 Hz, 2H), 6.98 (s, 2H),
6.20 (s, 2H), 4.95 (s, 4H), 3.25–3.07 (m, 24H), 2.40 (s, 6H), 1.57 (s,
24H), 1.32 (d, J=13.39, 6.58 Hz, 24H), 0.94 ppm (t, J=7.00 Hz,
36H). FTIR (KBr): n˜ =3341 (w), 2960 (s), 2936 (s), 2872 (s), 1716 (s),
1681 (s), 1617 (w), 1560 (vw), 1484 (s), 1387 (m), 1348 (w), 1256
(w), 1151 (w), 1129 (w), 1108 (m), 1040 (s), 941 (s), 921 (s), 904 (s),
666 cmꢀ1 (vs); elemental analysis calcd (%) for C86H155MnMo6N7O34.5
C 41.82, H 6.33, N 3.97; Found C 41.66, H 6.23, N 3.55.
:
Crystal data
2[(TBA)3(MnMo6O18{(OCH2)3CNHC12H9O4}2)]·4C3H7NO·H2O, M=4939.5;
¯
triclinic; space group P1 (2); a=18.4101(4), b=18.6082(3), c=
Figure 8. GPC curves of compound 3 and the C-(A-C-C)n-A-C polymer of
compound 3.
20.3260(4) ꢀ; a=64.329(2), b=65.195(2), g=60.647(2)8; V=
5276.57(22) ꢀ3. CCDC-963940 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
pound 3 at 365 nm resulted in polymerization through a light-
driven cyclobutane-type dimeric species. This process has been
characterized in solution by UV/Vis, 1H NMR, 2D NMR (COSY)
spectroscopy, and by DLS measurements. Film samples of com-
pound 3, in the presence of agarose, have been prepared. The
change in the fluorescence properties of these film samples
provides further evidence for a reversible light-modulated pro-
cess resulting from polymerization.
Preparation of film sample
The agarose films of compound 3 were synthesized by a facile gel-
casting method. Agarose powder (0.2 g) was added slowly to DMF
(10 mL) with vigorous stirring at 808C, to create a cloudy suspen-
sion, for 1 h. Compound 3 was then added to the clear casting so-
lution under vigorous stirring. After elimination of the micro-bub-
bles in a vacuum oven, the mixture was cast on indium-tin oxide
glass substrates, and dried at 808C overnight. Then, the self-sup-
porting film was peeled from the substrates.
Experimental Section
All chemicals were purchased from Alfa Aesar and were used with-
out further purification except for MeCN, which was dried by distil-
Acknowledgements
1
lation in the presence of CaH2 prior to use. H and 13C NMR spectra
This work was supported by the National Natural Science
Foundation of China (21076020, 21222104), the Fundamental
were recorded on a AV400 NMR spectrometer with [D6]DMSO sol-
vent. The electrospray mass spectra (ESI-MS) of compounds 1 and
Chem. Eur. J. 2014, 20, 1500 – 1504
1503
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim