A diarylethene as the SO2 gas generator upon UV irradiation

Article abstract of DOI:10.1039/c4cc07790c

A closed-ring isomer of a diarylethene having a sulfone group works as the reagent for SO₂ gas generation with thermal stability even at 70°C, and it rapidly reverts to the open-ring isomer and generates the SO₂ gas to induce cell death upon UV irradiation.

Full text of DOI:10.1039/c4cc07790c

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: R. Kodama, K.
Sumaru, K. Morishita, T. Kanamori, K. Hyodo, T. Kamitanaka, M. Morimoto, S. Yokojima, S. Nakamura and
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/chemcomm

Page 1 of 3
ChemComm
Dynamic Article Links ►
Journal Name
View Article Online
DOI: 10.1039/C4CC07790C
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
A diarylethene as the SO gas generator upon UV irradiation
2
a
b*
b
b
a
Ryuhei Kodama, Kimio Sumaru, Kana Morishita, Toshiyuki Kanamori, Kengo Hyodo, Takashi
c
d
e,f
f
a*
Kamitanaka, Masakazu Morimoto, Satoshi Yokojima, Shinichiro Nakamura, and Kingo Uchida
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
5
DOI: 10.1039/b000000x
A closed-ring isomer of a diarylethene having sulfone group
works as the reagent for SO2 gas generator with thermal
stability even at 70 °C, and it rapidly reverts to the open-ring
isomer and generates the SO gas to induce the cell death
2
1
0
upon UV irradiation.
Since the development of the photochromic compounds in the
Scheme 1. Molecular structures of the two isomers of diarylethene 1
late 1980s, diarylethenes have been attracted widespread attention
1,
as photocontrollable element in molecular devices and switches.
2
This is due to the high fatigue resistance of the cyclization and
cycloreversion reactions, which reversibly generate the openꢀ and
closedꢀring isomers. However, the reports to the biochemical and
biological applications were still very rare. Branda et al.
demonstrated that the photoresponsive dithienylethene could be
reversibly triggered in a living organism and that the photoswitch
induced paralysis in Caenorhabditis elegans only when the
closedꢀring isomer was generated by exposure with UV light (365
1
.2
.0
1
2
2
3
3
4
4
5
0
5
0
5
0
5
Irradaited
UV region
1
0.8
0
.6
.4
0
3
nm). Until today, the mechanism of the photoswitchable
paralysis is not clear.
0.2
.0
Some diarylethenes with sulfone groups are known as fatigue
resistant photochromic compounds with dramatic fluorescence
intensity changes upon alternate irradiation with UV and visible
0
2
00
300
400
Wavelength / nm
500
600
4ꢀ6
light. We found that one of the diarylethene derivatives having
sulfone group 1o (Scheme 1), which was initially synthesized by
ꢀ5
Fig. 1 Absorption spectral changes of 1o in hexane solution (4.24×10
7
S. I. Yang et al, works as SO gas generator to induce the cell
M). (a) Absorption spectrum of 1o (black solid line), (b) absorption
spectrum of 1c (red solid line), and (c) photostationary state upon 365
nm light irradiation (1o: 1c=34:66) (red dashed line).
2
death upon UV irradiation. Sulfur dioxide (SO2) is an
environmental pollutant and toxic at elevated concentrations.
Although the mechanism of its cytotoxicity is yet unclear, SO at 50 irradiation but also heating. Therefore the fatigue resistance of the
2
elevated concentrations is known to induce oxidative damage to
photochromism of 1 in hexane was poor (ESI†). The quantum
yield of SO gas generation of 1o was estimated as 0.1 (ESI†).
Herein we propose 1c as the thermally stable unique regent for
SO gas storage and generator.
Although diarylethenes are generally known as thermally
irreversible photochromic compounds, we confirmed the thermal
stability of both isomers 1o and 1c. The hexane solution of the 1c
was heated at 70 °C for 7 days in the dark, SO gas formation and
8ꢀ11
biomacromolecules such as proteins, lipids, and DNA.
2
Oxidation of SO to sulphate is known to occur through radical
2
intermediates (such as ·SO ) in neutral pH conditions, which in
3
2
8
ꢀ11
turn can damage biomacromolecules.
In such background,
55
8
1
reagents to generate SO gas in situ have been developed.
2
Diarylethene 1o shows the reversible coloration and
decoloration by alternate irradiation with UV and visible light.
2
4
ꢀ1
ꢀ
Openꢀring isomer 1o has the λmax at 229 nm (
ε
: 1.67 × 10 M cm
thermal cycloreversion reaction from 1c to 1o were not observed.
1
)
and the band extends to 400 nm, while the closedꢀring isomer 60 Upon visible light (
c has the λmax at 477 nm (ε: 1.05 × 10 M cm ) and the color is
λ
> 480 nm) irradiation, only cycloreversion
reaction to 1o was observed without gas formation. In contrast,
UV (300 nm < < 365 nm) irradiation to the hexane solution of 1o,
gas was detected accompanied with the cyclization reaction to 1c.
We identified the generated gas by the GCꢀMass spectroscopy for
4
ꢀ1
ꢀ1
1
orange in hexane (Fig. 1), and quantum yields of the cyclization
λ
ꢀ
and cycloreversion reactions of 1 are 0.35 (366 nm) and 4.2 × 10
3
12,13
(533 nm), respectively.
The isomer 1c is thermally stable
and never generates the SO gas by heating nor by visible light 65 the chloroform solution of 1o in a closedꢀvessels upon irradiation
2
irradiation. By contrast, 1o generate SO gas not only by light
with UV (300 nm<
λ
<365 nm). The gas consisted of SO, SO2,
2
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 | 1

ChemComm
Page 2 of 3
View Article Online
DOI: 10.1039/C4CC07790C
(
CH ) SiꢀOH, and the solvent (Fig. S1, ESI†). Then we used SO
substrates. At the photoꢀtoxicity experiment, NIH/3T3 and
3
3
2
gas test tube for the quantitative measurement (Fig. S2,S3 ESI†).
MDCK cells were disseminated onto thin layers of 1o and 1c,
By increasing the duration of UV irradiation, the amount of the 45 respectively. The photoirradiation to the thin layers containing 1o
generated SO gas was increased (Fig. S4, ESI†). The SO gas
or 1c can be controlled by selecting the wavelengths of irradiation
2
2
5
0
5
0
5
was also detected by heating the hexane solution of 1o in a sealed
tube at 70 °C for 1 day. These results indicate that the SO2
generation ability was locked in the closedꢀring isomer 1c and
light at 365 and 436 nm which are switchable on our PCꢀ
controlled microprojection system. To both cells, 365 nm light
was irradiated to the patterned area (four band shaped area)
16
unlocked
by
visible
light
irradiation
(one
way 50 through the filter from bottom side of the culture substrate. Fig.
photoisomerization).
3a shows the NIH/3T3 cells on the thin layer of 1o. The 365 nm
1
1
2
2
The protection was also unlocked by UV light irradiation
light was irradiated on the patterned area (Fig. 3b, fluorescence
from base polystyrene substrate was observed in the irradiated
area), and the cells on the area were damaged and detached from
(
back and forth photoisomerization) and SO gas was generated
2
from 1o after photoꢀconverted from 1c. The formation of SO gas
2
upon UV irradiation to the hexane solution of 1o as well as 1c are 55 the surface as shown in Fig. 3c. Also MDCK cells on the thin
measured by a gas detector and summarized in Fig. 2 (Tables S1ꢀ
S3, ESI†). Therefore, it is possible to use 1c as the thermally
layer of 1o were damaged after 365 nm irradiation (Fig. 3d, e),
while no damage was observed with 436 nm light irradiation. Fig.
3d shows that the adhesion of the cells decreased in the irradiated
area. Some of these cells were stained with Trypan which can
stable regent for SO gas storage. One of the useful applications
2
of this finding for cell biological reserches is that, once UV light
is irradiated, it works as photoinduced onꢀdemand killing of 60 stain the dead cells only. These results suggested that the cells
adherent cells on culture substrates.
were damaged significantly by 365 nm irradiation on the thin
layer of 1o. On the 1c film, NIH /3T3 cells were also damaged
upon 365 nm irradaition (Fig. 3f). The more magnified images
(Fig. 3g, h) show cleary that the shape of the cells in the
When we reduced the light intensity by using neutral density
(
ND) filters (Fig. S5, S6), the amount of SO gas generation from
2
1
c was much suppressed than that from 1o. This is attributed by
the following reason. For the hexane solution of 1c, the first 65 irradaited area were totally deformed indicating their critical
photon absorbed by 1c is used for the cycloreversion reaction to
damage.
1o. The produced 1o can generate SO gas but the concentration
2
of 1o is low because of the reduced intensity of UV light at the
initial stage of the experiment. Consequently, the ratio between
the generation of SO from 1o initially and that from 1c is larger
2
for the reduced intensity of UV light (Fig. 2).
7
1o
1
c
6
5
4
3
2
1
0
1
o ND filter 50%
c ND filter 50%
1o ND filter 20%
c ND filter 20%
1
1
0
50
100
150
200
250
300
350
400
Time / s
30
35
40
2
Fig. 2 SO gas formations by the UV irradiation to the hexane solution of
1
o and 1c with changing the UV intensity using ND filters.
The photoinduced SO gas generation from 1o is much easier
2
4
ꢀ6
compared to other diarylethene derivatives. This is most likely
due to the shorter conjugation length in the molecular backbone.
The thiophene 1,1ꢀdioxide in which no lone pair electrons exist
1
4,15
on the sulfur atom is not aromatic.
The SO gas generated
2
vigorously upon UV irradiation as well as on heating (ESI†).
Here, we further studied photoinduced cell damage on the
substrates and found the cell death upon UV irradiation to the 1o
coated substrates with NIH/3T3 and MDCK cells. The
phenomena were also observed for the cells on the 1c coated
Fig. 3 Influence of patterned UV irradiation (wavelength: 365 nm,
intensity: 90 mW/cm ) on NIH/3H3 (aꢀc, fꢀh) and MDCK (d, e) cells on
2
1
o coated substrate (aꢀe), and 1c coated substrate (fꢀh). Phase contract
2
70
images of NIH/3T3 cells on 1o coated substrate (0.44 ꢀg/cm ) before the
irradiation (a), during the 365 nm light irradiation for 8 min (b), and 3
hours after the irradiation (c). Phase contrast image of MDCK cells on 1o
2
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 3 of 3
ChemComm
View Article Online
DOI: 10.1039/C4CC07790C
2
coated substrate (0.44 ꢀg/cm ) 2 hours after 365 nm light irradiation for
Education, Culture, Sports, Science and Technology)ꢀSupported
Program for the Strategic Research Foundation at Private
Universities. The authors are also grateful thank to Zeon Co.,
Ltd., for providing the octafluorocyclopentene to synthesize 1o,
55 T. Sakurai of JEOL Resonance Ltd. for DOSY measurements,
and J. Okuda and K. Takase for quantum yield measurement of
1
2 min (d) and transmission image after subsequent Trypan blue dyeing
e). Phase contrast image of NIH/3T3 cells on 1c coated substrate (0.30
g/cm ) 2 hours after 365 nm light irradiation for 12 min (f), phase
contrast image after subsequent Trypan blue dyeing (g) and transmission
(
2
ꢀ
5
image of the same view field (h). (Scale bars in all figures: 500 ꢀm)
SO gas generation.
2
We then carried out the cell damage experiment on the PMMA
1
0
films containing 1c. The cells were attached before UV
irradiation. UV light (365 nm, 95 mW/cm ) was irradiated to the
central part for 8 min (Figure 4).
Two hours later the irradiation, the cells in the irradiated area
were damaged and departed from the surface. In the control
experiment, such cell damage was not observed on the PMMA
film without 1c under the same UV irradiation conditions.
Notes and references
2
a
Department of Materials Chemistry, Faculty of Science and Technology,
6
6
7
7
0
5
0
5
Ryukoku University, Seta, Otsu, Shiga 520-2194, Japan, Fax: +81-77-
5
43-7483; Tel: +81-77-543-7462; E-mail; uchida@rins.ryukoku.ac.jp
b
Research Center for Stem Cell Engineering, National Institute of
Advanced Industrial Science and Technology (AIST), Tsukuba Central 5th,
1
5
1
-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
Industrial Research Center of Shiga Prefecture, Kamitoyama 232, Ritto,
c
The byꢀproducts formed during the SO gas generation were
2
Shiga 520-3004, Japan.
d
similar to those reported by Kobatake et al, and the byꢀproducts
Department of Chemistry and Research Center for Smart Molecules,
1
7
were maintained in PMMA matrix.
Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501,
Japan
e
School of Pharmacy, Tokyo University of Pharmacy and Life Sciences,
1
432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
f
RIKEN Research Cluster for Innovation, Nakamura Laboratory, 2-1
Hirosawa, Wako, Saitama 351-0198, Japan
† Electronic Supplementary Information (ESI) available: [Experimental
Section, Absorption spectral changes of 1o in hexane solution,
Generated amount of SO gas by gas detector without ND filters,
2
GCꢀMass spectroscopy of UV generated substance in gas phase,
Detection of sulfur dioxide by a gas detector, and Discussion about
80 decomposition mechanism]. See DOI: 10.1039/b000000x/
2
2
3
0
5
0
Fig. 4 Optical microscopic images of NIH/3T3 cells on a PMMA (64
2
2
ꢀ
g/cm ) film containing 1c (7.2 ꢀg/cm ). (a) Before 365 nm light
2
irradiation, (b) 2 h later after 365 nm (95 mW/cm ) light irradiation for 8
1
2
M. Irie, Chem. Rev., 2000, 100, 1685ꢀ1716.
B. L. Feringa and W. B. Browne Ed.; Molecular Switches; Wileyꢀ
VCH: Weinheim, Germany, 2011.
min. (Scale bars: 500 ꢀm)
The diarylethenes having longer conjugations showed high 85 3 U. AlꢀAtar, R. Fernandes, B. Johnsen, D. Baillie and N. R. Branda, J.
5,6
Am. Chem. Soc., 2009, 131, 15966ꢀ15967.
fatigue resistance even they possess the SO2 groups. The
effective photoinduced elimination of sulfur dioxide will be
limited within simple structured derivatives. Diarylethene 1o is
4
5
6
7
8
9
1
1
1
K. Uno, H. Niikura, M. Morimoto, Y. Ishibashi, H. Miyasaka and M.
Irie, J. Am. Chem. Soc., 2011, 133, 13558ꢀ13564.
T. Fukaminato, T. Doi, M. Tanaka M. Irie, J. Phys. Chem. C, 2009,
113, 11623–11627.
T. Fukaminato, T. Doi, N. Tamaoki, K. Okuno, Y. Ishibashi, H.
Miyasaka and M. Irie, J. Am. Chem. Soc., 2011, 133, 4984ꢀ4990.
Y.ꢀC. Jeong, D. G. Park, E. Kim, K.ꢀH. Ahn and S. I. Yang, Chem.
Commun., 2006, 1881ꢀ1883.
S. R. Malwal, D. Sriram, P. Yogeeswari, V. B. Konkimalla and H.
Chakrapani, J. Med. Chem.,2012, 55, 553ꢀ557.
G. A. Reed, J. F. Curtis, C. Mottley, T. E. Eling and R. P. Mason,
Proc. Natl. Acad. Sci. USA, 1986, 83, 7499ꢀ7502.
0 X. Shi and Y. Mao, Biochem. Biophys. Res. Commun., 1994, 205, 141
−147.
the special compound in that the SO gas generation is moderate
90
2
and the absorption wavelength is longer compared to that of
thiophene 1,1ꢀdioxide, and the degradation process is prohibited
by forming the closed ring structure. Therefore, diarylethene 1c
has desirable characteristics as the photoinduced cell killing
culture substrate for cell control.
95
3
5
Conclusions
1
1
00
Photoinduced elimination reaction of sulfur dioxide was found
1 H. Yi, J. Yin, X. Liu, X. Jing, S. Fan and H. Zhang, Ecotoxicol.
Environ. Saf., 2012, 78, 281ꢀ286.
2 Y.ꢀC. Jeong, E. Kim, K.ꢀH. Ahn and S. I. Yang, Bull. Korean Chem.
Soc., 2005, 26, 1675ꢀ1676.
as biologically useful SO gas generator accompanied with the
2
photochromism of diarylethene 1o. For the closedꢀring isomer 1c,
the gas generation was prohibited without UV irradiation even at
70 °C, however once UV light (365 nm) was irradiated, it reverts
to 1o and sulfur dioxide gas was generated. Due to the generated
gas, selective cell damage was observed. Such photoinduced onꢀ
demand killing of adherent cells on culture substrates will be
applicable as one of the noncontact cell control technique.
05 13 A. Uyama, S. Yamazoe, S. Shigematsu, M. Morimoto, S. Yokojima,
4
4
5
0
5
0
H. Mayama, Y. Kojima, S. Nakamura and K. Uchida, Langmuir,
2
011, 27, 6395ꢀ6400.
1
4
H. Nagasawa, Y. Sugihara, A. Ishii and J. Nakayama, Bull. Chem.
Soc. Jpn., 1999, 72, 1919ꢀ1926.
110 15 J. Nakayama, H. Nagasawa, Y. Sugihara and A. Ishii, J. Am. Chem.
Soc., 1997, 119, 9077ꢀ9078.
1
6
K. Sumaru, K. Kikuchi, T. Takagi, M. Yamaguchi, T. Satoh, K.
Morishita and T. Kanamori, Biotechnol. Bioeng., 2013, 110, 348ꢀ352.
This work was partially supported by AꢀSTEP (Adaptable &
Seamless Technology Transfer Program through Targetꢀdriven 115
R&D) FS stage: Exploratory Research from the Japan Science
and Technology Agency (JST) and MEXT (Ministry of
1
7 H. Shoji and S. Kobatake, Chem. Commun., 2013, 49, 2362ꢀ2364.
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 |
3