Synthesis of a new spiropyran based on [60]fullerene unit

Article abstract of DOI:10.1081/SCC-120004254

A new compound 2: spiropyran with [60]fullerene unit was synthesized and characterized by FT-IR, MALDI-TOF MS, NMR, and UV-Vis spectra.

Full text of DOI:10.1081/SCC-120004254

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SYNTHETIC COMMUNICATIONS, 32(11), 1647–1652 (2002)
SYNTHESIS OF A NEW SPIROPYRAN
BASED ON [60]FULLERENE UNIT
Ju-Hua Xu,1, Yu-Liang Li,2 and Dao-Ben Zhu2
*
1College of Chemistry and Chemical Engineering,
Hunan University, Changsha Hunan,
410082, P.R. China
2Institute of Chemistry, The Chinese Academy of
Sciences, Beijing 100080, P.R. China
ABSTRACT
A new compound 2: spiropyran with [60]fullerene unit was
synthesized and characterized by FT-IR, MALDI-TOF MS,
NMR, and UV–Vis spectra.
The [60]fullerene chemistry has developed rapidly in over a decade
since it has some special properties and potential uses in functional
materials.[1–3] Recently [60]fullerene dyads, which have some functional
groups such as: tetrathiafulvalene (TTF), porphyrin, phthalocyanine, and
tetracyano-p-quinodimethane (TCNQ) covalently attached on [60]fullerene
surface, have attracted much attention.[4] Many of these works have focused
on synthesis of C60 dyads using [1,3]-dipolar cycloaddition reactions of C60
and azomethine yield which can be generated in situ from the reaction of
ꢀ-aminoacid with aldehyde. Spiropyran has been studied widely since
Fischer first discovered that it had allochromatic process.[5] Some allochro-
*Corresponding author. E-mail: jhxu@mail.hunu.edu.cn
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1648
XU, LI, AND ZHU
nic processes of spiropyran with crown ether[6] and 8-hydroxyl quinoline[7]
have been also reported. However there has been no report on the spiro-
pyran connected with [60]fullerene so far. In the present paper, we design,
synthesize, and characterize a new [60]fullerene derivative; that is, a spiro-
pyran covalently linked to a [60]fullerene unit (Scheme 1).
Scheme 1.
The compounds 1 and 2 are well characterized by FT-IR,
MALDI-TOF MS, NMR, and UV–Vis spectra, and the spectra data

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SPIROPYRAN WITH [60]FULLERENE UNIT
1649
Figure 1. The UV–Vis spectrum of compound 2 in chloroform (dotted line) (solid
line: adding DMF; dashed line: adding methanol).
elucidate that the structures of compounds 1 and 2 are described as in
Scheme 1.
In the UV–Vis spectrum of compound 2 (Figure 1, in chloroform,
a dotted line), we find the absorption bands consisted of two parts: the
visible region (lmax 582 nm), which is dominated by merocyanine dye,
and the UV region, which is dominated by fullerene (lmax 257, 324 and
430 nm). The maximum absorption of merocyanine dye in compound 2 is
red shifted by 15 nm compared to that in merocyanine dye connected with
crown ether.[6]
Figures 1 and 2 show that compound 2 has an allochroic
process toward polar solvents and acids. But the photochromic process of
compound 2 is less sensitive toward light than that of a spiropyran molecule
without a [60]fullerene unit. Further researches are in program.
EXPERIMENTAL SECTION
C60 (>99.5%), 5-nitro-salicylaldehyde, and 5-formacyl-2-methyl-
benzothiazole were synthesized according to the literature[8] and footnote[9]
respectively. Other chemicals were available commercially.

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XU, LI, AND ZHU
Figure 2. The UV–Vis spectrum of compound 2 in chloroform and methanol
(v/v 5 : 1, dashed line) (solid line: adding acetic acid; dotted line: adding NaOC2H5).
The FT-IR, MS, UV–Vis, and NMR were performed by IFS-113
Fourier Transfer Infrared, BIFLEX III, U3010 ultraviolet-visible instrument,
and Bruker DMX300 or Bruker AM 500 respectively. Tetramethylsilane was
used as internal standards in CDCl3 for 1H and 13C NMRspectra.
Compound 1 was prepared as follows. To a solution of C60 (28.8 mg) in
30 ml toluene, sarcosine (7.1 mg) and 5-formacyl-2-methylbenzothiazole
(10.6 mg) were added. The mixture was stirred and heated to reflux under
nitrogen for 6 h. The solution was concentrated and chromatographed on
silica-gel using toluene-ethyl acetate (8 : 1, v/v) as the eluent to give the com-
pound 1 in 60% yield based on converted C60 (42%). MALDI-TOF MS, m/z:
932.07 (relative intensity 100%, Mþ-1 for C71H12N2S) with the peak for
[60]fullerene at m/z 720.00. FT-IR(KBr pellet): 2946.40, 2780.18, 1643.94,
1525.00, 1427.99 (C60), 1177.18, 1023.99, 527.05 (C60) cmÀ1 1H-NMR
.
(CDCl3, 300 MHz), ꢁ: 2.84 (s, 3H, CH3); 2.88 (s, 3H, CH3); 4.35 (d, 1H);
5.22 (dd, 2H), 7.13 (t, 1H); 7.21 (d, 1H); 7.90 (t, 1H). 13C-NMR(CDCl ,
3
125 MHz) ꢁ c: 169.81 (C¼N), 153.22, 152.39, 147.42, 146.40, 146.33, 146.23,
146.03, 145.85, 145.77, 145.66, 145.50, 145.42, 145.36, 144.91, 144.55, 144.39,
143.15, 142.76, 142.67, 142.35, 142.26, 142.18, 142.05, 141.96, 141.74, 141.58,
410.26, 135.75, 135.88, 125.88, 123.66, 122.30, 83.53, 66.95, 68.48, 39.99,
20.09. UV–Vis (in chloroform): lmax 255, 327 and 430 nm (the peak at
430 nm is a characteristic absorption which resulted from a closed [6,6] addi-
tion of [60]fullerene).

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SPIROPYRAN WITH [60]FULLERENE UNIT
1651
Formation of compound 2 was achieved via the following process:
45 mg of compound 1 and dimethyl sulfate (1 ml) were added in a 5 ml
round-bottomed flask. The mixture was stirred and heated at 140ꢀC under
nitrogen for 2 h, then cooled down to room temperature. Ethyl ether was
added, and the precipitates were filtered and dried. To this precipitates were
added pyridine (1 ml), 5-nitro-salicylaldehyde (10 mg) and ethanol (4 ml) in a
5 ml round-bottomed flask. The mixture was stirred and heated to reflux for
8 h. Compound 2 was separated by silica-gel chromatography using chloro-
form and methanol (8 : 1) as the eluent to give compound 2 in 40% yield.
MALDI-TOF MS, m/z: 1086.21 (Mþ-1, for C79H17N3O3S) together with
some fragment peaks at m/z 1041.22, 937.23, 923.18 and 874.37. FT-IR
(KBr pellet), ꢂ: 2922.49, 2849.78, 2784.44, 1603.08, 1531.25 (NO2),
1495.92 (C¼C in spiropyran), 1456.94, 1337.62 (NO2), 1291.08, 1250.22,
1162.55, 1093.22, 1014.45, 770.59 (C¼C-H indicates that the compound 2
1
is cis configuration), 576.63 (C60), 526.94 (C60) cmÀ1. H-NMR(CDCl ,
3
300 MHz), ꢁ: 2.04 (s, 6H, 2CH3), 3.77 (s, 1H), 4.08 (dd, 2H). 4.66 (s, 2H),
8.09 (2H), 8.15 (2H), 9.09 (2H). UV–Vis (in chloroform), lmax 257, 324, 430,
582 nm.
ACKNOWLEDGMENT
The present work was supported by NSFC (No: 29871032) and
Chinese Academy of Sciences for financial support of the research.
REFERENCES
1. Hirsch, A. The Chemistry of the Fullerene; Georg Thieme: Verlag,
Stuttgart, 1994.
2. Dresselhaus, M.S.; Dresselhaus, G.; Eklund, P.C. Science of Fullerenes
and Carbon Nanotubes; Academic Press: San Diego, 1996.
3. Taylor, R.; Walton, D.R.M. Nature 1993, 363, 685.
4. Martin, N.; Sanchez, L.; IIIescas, B.; Pereg, I. Chem. Rev. 1998, 98,
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5. Bercovici, T.; Teiligman-Rim, R.; Fischer, E. Mol Photochem. 1969,
1, 23.
6. Wu, D.X.; Xia, P.F.; Zhao, H.M. Youjihuaxue (Chinese) 1992, 12, 76.
7. Collins, G.E.; Chol, L.S.; Ewing, K.J.; Michelet, V.; Brown, C.M.;
Winkler, J.D. J. Chem. Soc. Chem. Commun. 1999, 321–322.
8. Shiminz, I.; Kodado, H.; Inone, E. Bull. Chem. Soc. Jpn. 1969, 42, 1730.

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1652XU, LI, AND ZHU
9.
Received in Japan April 3, 2001