Reversible Laser-Induced Bending of Pseudorotaxane Crystals

Article abstract of DOI:10.1021/jacs.7b10998

This study investigated the dynamic photoresponse of pseudorotaxane crystals with azobenzene and ferrocenyl groups in the axle component. X-ray crystallography showed pseudorotaxanes with a methylazobenzene group and a dibromophenylene ring in the cyclic component to exhibit twisting of the trans-azobenzene groups at torsion angles of 17° and 38°, respectively. Repeated alternating laser irradiation of the crystals at 360 and 445 nm produced bending of 20-30° in opposite directions, with no evidence of decay. Under 445 nm irradiation, bending took place within 0.3 s. A crystal of nonsubstituted pseudorotaxane showed bending of only 2° under 360 nm irradiation due to multiple π-π interactions between the planar trans-azobenzene groups. The pseudorotaxane crystals have two chromophores, bent rapidly and reversibly on irradiation at rates depending on the molecular structure.

Full text of DOI:10.1021/jacs.7b10998

Subscriber access provided by READING UNIV
Communication
Reversible Laser-Induced Bending of Pseudorotaxane Crystals
Shao-Chi Cheng, Kai-Jen Chen, Yuji Suzaki, Yoshitaka
Tsuchido, Ting-Shen Kuo, Kohtaro Osakada, and Masaki Horie
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.7b10998 • Publication Date (Web): 23 Dec 2017
Downloaded from http://pubs.acs.org on December 23, 2017
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a free service to the research community to expedite the
dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts
appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been
fully peer reviewed, but should not be considered the official version of record. They are accessible to all
readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered
to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published
in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just
Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor
changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers
and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors
or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Journal of the American Chemical Society is published by the American Chemical
Society. 1155 Sixteenth Street N.W., Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 11
Journal of the American Chemical Society
Reversible Laser-Induced Bending of Pseudorotaxane Crystals
1
2
3
4
Shao-Chi Cheng,† Kai-Jen Chen,† Yuji Suzaki,‡ Yoshitaka Tsuchido,‡ Ting-Shen Kuo,§ Kohtaro
Osakada,‡ and Masaki Horie*,†
5
6
7
8
†Department of Chemical Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 30013,
Taiwan
‡Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259
Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
9
§ Department of Chemistry, National Normal University, No. 88, Section 4, Tingzhou Road, Taipei, 11677, Taiwan
Supporting Information Placeholder
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
shape of the crystals to change in a much less anisotropic manner
and more rapidly than when thermal induction was used.
ABSTRACT: This study investigated the dynamic photoresponse
of pseudorotaxane crystals with azobenzene and ferrocenyl groups
in the axle component. X-ray crystallography showed
The photomechanisms involving photochemically active organic
compounds have been intensively investigated.18-20 As shown in
Figure 1, the current study applied azobenzene groups to the
pseudorotaxanes and investigated the effect of laser irradiation on
the crystal structure. Azobenzene-containing molecules have been
intensively studied as they are known to undergo cis-trans
isomerization when driven by specific wavelengths of light or
heat.21-26 Their high isomerization efficiency and reversibility
makes their compounds suitable in a wide range of applications,
including optical data storage23 and as photoresponsive
biomaterials.24 A number of research groups have reported
achieving isomerization of the azobenzene group when in the solid
state, producing macroscopic mechanical motion.21,25-27 For
example, single crystals made up of the azobenzene group have
demonstrated reversible bending motion when exposed to
photoirradiation.26,27
pseudorotaxanes with
a
methylazobenzene group and
a
dibromophenylene ring in the cyclic component to exhibit twisting
of the trans-azobenzene groups at torsion angles of 17° and 38°,
respectively. Repeated alternating laser irradiation of the crystals at
360 and 445 nm produced bending of 20–30° in opposite directions,
with no evidence of decay. Under 445-nm irradiation, bending took
place within 0.3 seconds.
A crystal of non-substituted
pseudorotaxane showed bending of only 2° under 360-nm
irradiation due to multiple π-π interactions between the planar
trans-azobenzene groups. The pseudorotaxane crystals have two
chromophores, bent rapidly and reversibly on irradiation at rates
depending on the molecular structure.
Rotaxanes and pseudorotaxanes consist of axle and ring
molecules and the interlocking pattern of these molecules allows
the ring to move along the axle under the control of external stimuli,
in a process known as shuttling.1-7 Therefore, they are considered
to be promising candidates for use in molecular machines and as
switches. However, while the dynamic performance of rotaxanes in
a solution has been extensively studied,8-10 few reports have
examined their structural control in the solid state.
In this communication, we report rapid and highly reversible
bending of the crystals of these pseudorotaxanes and discuss the
relationship between molecular structure and mechanical output.
We expected that the molecular motion of the azobenzene group
would be controlled by the ring molecule, whereas the ferrocenyl
group would act as a photosensitizer.
When arranged as an oriented film, rotaxanes can act as
molecular machines and can be used to convert photoenergy or
chemical energy into work at the film surface.11-13 The
unidirectional control of the motion of a droplet on a rotaxane-
coated surface by application of photoirradiation has been
reported.11 Another study demonstrated an artificial molecular
muscle, operated by shuttling rotaxanes in a monolayer film and
detected by the cantilever of an atomic force microscope.12
Shuttling has also been used to control electrical conductivity,
creating high-density molecular memory on a crossed electrode.13
Fewer studies have examined the behavior of rotaxanes when in
the crystalline state.6,14,15 The rotaxane species have an ordered
alignment owing to the crystallographic symmetry, and in the
course of phase transition, a macroscopic change in their physical
properties may be observed. The molecular structure can also be
observed directly, and single-crystal X-ray crystallography can
reveal the source of the motion at the molecular level. In recent
papers, we reported photo- and thermally induced crystal-to-crystal
Figure 1. Schematic illustration of cis-trans isomerization of
azobenzene-containing pseudorotaxanes and photoinduced
bending of a crystal.
phase transition of
a
[2]pseudorotaxane comprising
axle and
a
a
ferrocenylmethyl(4-methylphenyl)ammonium
dibenzo[24]crown-8 ether (DB24C8) ring.16,17 Thermal phase
transition occurred at 128 °C and was accompanied by the
shortening of the c-axis (5%) and elongation of the b-axis (7%).
Laser irradiation at 445 nm caused the molecular alignment and
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 11
Scheme 1 summarizes the formation of [2]pseudorotaxanes 1-3
(see also Figures S1–S14 in the Supporting Information). They
were produced in the anisotropic plate crystal form by dissolution
of an equimolar mixture of dialkylammonium containing an
azobenzene group and the ring molecule DB24C8, or its tetrabromo
derivative DB24C8-Br4, in CH2Cl2, followed by crystallization by
diffusion of Et2O vapor.
1
2
3
4
5
6
7
8
Scheme 1. [2]Pseudorotaxane formation
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 2 shows the molecular structures and intermolecular
interactions, identified using single-crystal X-ray crystallography
(see also Figure S15 and Tables S1 and S2 in the Supporting
Information). The axle and cyclic components were formed by
N─H⋯O hydrogen bonding and C─H⋯π interactions between the
cyclopentadienyl group of ferrocene in the axle and an aromatic
ring D of the catechol group in the cyclic component of the
pseudorotaxanes. Each pseudorotaxane was stabilized by intra- and
intermolecular interactions in a different manner.
As shown in Figure 2a, pseudorotaxane 1 assumed a relatively
planar trans-azobenzene conformation, in which aromatic rings A
and B of the azobenzene group are slightly tilted each other with a
plane angle of 4.2°. Intermolecular π-π stacking interactions were
also observed between pairs of azobenzene groups (aromatic rings
A-B’ and A’-B) at a distance of 4.5 Å. This suggests that the
azobenzene groups acted to stabilize the crystal structure and
restrict the motion of the molecules. We return to this below.
Figure 2. Molecular structures of (a) 1, (b) 2, and (c) 3 derived
using single-crystal X-ray crystallography. Intra- and
intermolecular π-π distances and angles are shown in illustrations.
In contrast, pseudorotaxanes 2 and 3 took a significantly twisted
trans-azobenzene form. The plane angle between aromatic rings A
and B was 38° for pseudorotaxane 2 and 17° for pseudorotaxane 3
(Figures 2b and 2c). Pseudorotaxane 2 exhibited intramolecular π-
π interaction between the azobenzene and catechol groups of
DB24C8 (aromatic rings B and C) at a distance of 3.8 Å, but no
intermolecular π-π interaction (the distance of 4.9 Å between
aromatic rings A and B’ was too great for π-π interaction to take
place). Two azobenzene terminal groups of
3 exhibited
intermolecular association between aromatic rings A and A’ at a
distance of 4.0 Å. However, the bulky bromo substituents
prevented other π-π interactions, for example between rings B and
C or B and A’. Therefore, both of these pseudorotaxanes were
expected to provide greater flexibility than pseudorotaxane 1 at the
terminal azobenzene group in the crystalline state.
A single crystal of 1 remained static when the top face of the
crystal (Miller index: 001) was subjected to wide-field 445-nm
laser irradiation at 90 mW for 25 sec (Figure 3a), but deformed
slightly when this was followed by 360-nm irradiation at 90 mW,
with a bend angle of +2° (Figure 3a (right)). In contrast, when one
surface of a crystal of 2 (Miller index: 001) was irradiated, negative
bending at an angle of -15° was observed under 445-nm irradiation
at 90 mW for 25 sec. From this state, a positive bending of +20°
was observed under 360-nm irradiation at 90 mW for 7 sec (Figure
3b).
Figure 3. Optical micrographs showing photoinduced mechanical
bending of crystals of (a) 1, (b) 2, and (c) 3 under wide-field laser
irradiation at 360 nm and 445 nm (90 mW). Crystal size: 600 x 200
x 20 µm3 for 1, 900 x 400 x 30 µm3 for 2, and 1000 x 500 x 30 µm3
for 3. See also the Supporting Videos.
ACS Paragon Plus Environment

Page 3 of 11
Journal of the American Chemical Society
When the 360-nm laser was turned off, the crystal spontaneously
isomerization of the trans-azobenzene group to cis. After
irradiation at 445 nm (50 mW, 30 sec), isomerization of the cis-
azobenzene group to trans caused the absorption intensity at 324
nm to increase significantly. The changes in the UV-vis spectra of
1 and of the pseudorotaxane comprising tolyl and azobenzene
groups are compared with each other (Figure S16 in the Supporting
Information). The cis-to-trans photoisomerization of 1 was faster
than that observed for its counterpart without ferrocenyl group.
regained its former shape within a few minutes, whereas 445-nm
irradiation caused the former shape to be regained within 0.3 sec.
Similarly, 445-nm irradiation of one surface of a crystal of 3 (Miller
index: 01-5) produced negative bending of -5°, and further 360-nm
irradiation produced positive bending of +30° compared to the
negative bending state (Figure 3c). When the 360-nm laser was
turned off, this state was maintained for several hours, whereas the
crystal quickly regained the negative bent shape under 445-nm
irradiation within 0.3 sec.
1
2
3
4
5
6
7
Pseudorotaxanes
2
and
3
also underwent similar
photoisomerization when in CH2Cl2 solution.
8
9
To quantify the rate and reversibility of crystal bending, the
experiments were repeated more than 200 times (Figure 4). The
crystal of 1, with its small bend angle, exhibited rapid up/down
bending at a rate of less than 0.4 sec. In contrast, the crystals of 2
and 3, with their bend angles of 20° and 30°, respectively, exhibited
up/down bending cycles of 7 sec and 30 sec, respectively. In both
cases, the reverse process was much faster than the forward
process, which took place in less than 0.3 sec.
Crystal state trans-to-cis isomerization was next induced at 360
nm (50 mW, 30 sec), and the crystals were then dissolved in CH2Cl2
(Figure 5a-5c (iii)). Based on the absorption intensities, the rate of
photoisomerization conversion in the crystal state was estimated to
be 4% for 1, 28% for 2, and 40% for 3.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 5. UV-Vis absorption spectra of (a) 1, (b) 2, and (c) 3 in
CH2Cl2 solution at 25°C. (i) As-synthesized crystal dissolved in
CH2Cl2. (ii) After irradiation at 360 nm (50 mW for 30 sec) in
CH2Cl2 solution. (iii) Crystals dissolved in CH2Cl2 after irradiation
at 360 nm (50 mW for 30 sec) in the crystal state.
Figure 4. Induced bending of (a) 1, (b) 2, and (c) 3 crystals under
alternating 360-nm and 445-nm wide-field laser irradiation at 90
mW.
We now consider the effect of the molecular structure of the
pseudorotaxanes on the mechanical output. Pseudorotaxane 1
contains the thermally stable planar trans-azobenzene group, which
exhibited little conformation change when in the crystal state under
irradiation at either 445 nm or 360 nm. The azobenzene groups
underwent multiple intermolecular π-π interactions, which strongly
restricted molecular movement. In contrast, crystals of 2 showed
significantly greater movement, with negative bending under 445-
nm irradiation and positive bending under 360-nm irradiation.
Significantly, the crystal showed reversible spontaneous cis-to-
trans isomerization. These properties were attributed to the
flexibility of the azobenzene group due to the absence of π-π
interactions at the terminal group (the free aromatic ring A in
The changes observed in the crystal shape were related to
isomerization of the azobenzene groups under laser irradiation. As
shown in Figure 5a (i), in CH2Cl2 solution the UV-vis absorption
spectrum of 1 showed maximum absorption (λmax) at a wavelength
of 324 nm and much weaker absorption at 450 nm. This was
attributed to the presence of azobenzene and ferrocenyl groups,
respectively. Irradiation at 360 nm (50 mW, 30 sec) caused the
absorption intensity at 324 nm to decrease significantly and a new
peak to appear at 430 nm (Figure 5a (ii)). This was due to
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 4 of 11
Figure 2b). Crystals of 3 showed similar bending motion under
This work was financially supported by Ministry of Science and
irradiation. However, the movement was slower than that of 2, and
the reverse cis-to-trans process was not spontaneous, but required
irradiation at 445 nm. These phenomena were attributed to the
presence of intermolecular π-π interactions at the terminal
azobenzene group (the partially restricted aromatic ring A in Figure
2c).
Technology Taiwan and Frontier Research Center on Fundamental
and Applied Sciences of Matters at National Tsing Hua University.
1
2
3
4
5
6
7
8
REFERENCES
(1) Erbas-Cakmak, S.; Leigh, D. A.; McTernan, C. T.; Nussbaumer, A. L.
Chem. Rev. 2015, 115, 10081.
(2) Fahrenbach, A. C.; Bruns, C. J.; Li, H.; Trabolsi, A.; Coskun, A.;
Stoddart, J. F. Acc. Chem. Res. 2013, 47, 482.
(3) Kay, E. R.; Leigh, D. A. Angew. Chem., Int. Ed. 2015, 54, 10080.
(4) Stoddart, J. F. Angew. Chem., Int. Ed. 2014, 53, 11102.
(5) Van Noorden, R.; Sauvage, J.-P. Nature 2016, 538, 152.
(6) Zhu, K.; O'keefe, C. A.; Vukotic, V. N.; Schurko, R. W.; Loeb, S. J.
Nat. Chem. 2015, 7, 514.
(7) Leigh, D. A.; Marcos, V.; Nalbantoglu, T.; Vitorica-Yrezabal, I. J.;
Yasar, F. T.; Zhu, X. K. J. Am. Chem. Soc. 2017, 139, 7104.
(8) Bibal, B.; Mongin, C.; Bassani, D. M. Chem. Soc. Rev. 2014, 43,
4179.
(9) Ma, X.; Tian, H. Acc. Chem. Res. 2014, 47, 1971.
(10)Vukotic, V. N.; Zhu, K.; Baggi, G.; Loeb, S. J. Angew. Chem. Int. Ed.
2017, 129, 6232.
(11)Berna, J.; Leigh, D. A.; Lubomska, M.; Mendoza, S. M.; Perez, E. M.;
Rudolf, P.; Teobaldi, G.; Zerbetto, F. Nat. Mater. 2005, 4, 704.
(12)Juluri, B. K.; Kumar, A. S.; Liu, Y.; Ye, T.; Yang, Y. W.; Flood, A.
H.; Fang, L.; Stoddart, J. F.; Weiss, P. S.; Huang, T. J. Acs Nano
2009, 3, 291.
(13)Zhang, W. Y.; DeIonno, E.; Dichtel, W. R.; Fang, L.; Trabolsi, A.;
Olsen, J. C.; Benitez, D.; Heath, J. R.; Stoddart, J. F. J Mater Chem
2011, 21, 1487.
(14)Tayi, A. S.; Kaeser, A.; Matsumoto, M.; Aida, T.; Stupp, S. I. Nat.
Chem. 2015, 7, 281.
(15)Coskun, A.; Hmadeh, M.; Barin, G.; Gándara, F.; Li, Q.; Choi, E.;
Strutt, N. L.; Cordes, D. B.; Slawin, A. M.; Stoddart, J. F. Angew.
Chem., Int. Ed. 2012, 51, 2160.
(16)Horie, M.; Suzaki, Y.; Hashizume, D.; Abe, T.; Wu, T.; Sassa, T.;
Hosokai, T.; Osakada, K. J. Am. Chem. Soc. 2012, 134, 17932.
(17)Chen, K.-J.; Tsai, Y.-C.; Suzaki, Y.; Osakada, K.; Miura, A.; Horie,
M. Nat. Commun. 2016, 7, 13321.
(18)Kim, T.; Al-Muhanna, M. K.; Al-Suwaidan, S. D.; Al-Kaysi, R. O.;
Bardeen, C. J. Angew. Chem. Int. Ed. 2013, 52, 6889.
(19)Nath, N. K.; Pejov, L.; Nichols, S. M.; Hu, C. H.; Saleh, N.; Kahr, B.;
Naumov, P. Journal of the American Chemical Society 2014, 136,
2757.
(20)Wang, H. R.; Chen, P.; Wu, Z.; Zhao, J. Y.; Sun, J. B.; Lu, R. Angew.
Chem. Int. Ed. 2017, 56, 9463.
(21)Ube, T.; Ikeda, T. Angew. Chem., Int. Ed. 2014, 53, 10290.
(22)Ragazzon, G.; Baroncini, M.; Silvi, S.; Venturi, M.; Credi, A. Nat.
Nanotechnol. 2015, 10, 70.
(23)Bruder, F. K.; Hagen, R.; Rolle, T.; Weiser, M. S.; Facke, T. Angew.
Chem. Int. Ed. 2011, 50, 4552.
(24)Azzarito, V.; Long, K.; Murphy, N. S.; Wilson, A. J. Nat. Chem.
2013, 5, 161.
The pseudorotaxane crystals comprise photoresponsive
azobenzene and ferrocenyl groups. Combining axle and ring
molecules with different substituents can modify the chemical
structure of the pseudorotaxanes, providing structural diversity.
The mechanical motion induced in each crystal by reversible cis-
trans photoisomerization is unique. Significant differences are
produced by the molecular structure and packing of the crystals,
which were revealed using single-crystal X-ray crystallography in
this study. The bending of the crystals can be assisted by the ring
molecule of pseudorotaxanes, which provide adjustability of
molecular structural change, resulting in a degree of flexibility of
the mechanical motion of the crystals. The crystals underwent cis-
to-trans reversal within 0.3 sec. Generally, azobenzene derivatives
exhibit fast forward change and slow reversal.25,27 This may be due
to the ferrocenyl group, which exhibits absorption at 445 nm,
enhancing the rate of cis-to-trans isomerization and producing the
characteristic “slow upward/fast downward” movement of the
crystals.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
We expect these unique dynamic crystals, composed of
interlocked molecules, to have applications as molecular actuators
or as switches in photoresponsive mechanical devices.
Pseudorotaxane 1 exhibited high-speed bending (0.3 sec for 1
cycle) with a small displacement, suggesting potential applications
in on/off current switching in electric circuits.17,28 Pseudorotaxane
2, with the flexibility provided by its Me-substituent on the
azobenzene group, exhibited spontaneous reversal of bending. This
would simplify the design of systems using on/off laser switching
at a single wavelength. Pseudorotaxane 3, which has tetrabromo-
substituents on DB24C8, exhibited the greatest bending under
photoirradiation. The cis-form was static at room temperature
unless additional stimuli were applied. These crystals may have
applications in multiple-state switches controlled by lasers of
different wavelengths.
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the ACS
Publications website.
Experimental details (PDF), crystal information files (CIF), movie
(mp4)
(25)Guo, S.; Matsukawa, K.; Miyata, T.; Okubo, T.; Kuroda, K.;
Shimojima, A. J. Am. Chem. Soc. 2015, 137, 15434.
(26)Koshima, H.; Ojima, N.; Uchimoto, H. J. Am. Chem. Soc. 2009, 131,
6890.
(27)Taniguchi, T.; Fujisawa, J.; Shiro, M.; Koshima, H.; Asahi, T. Chem.
Eur. J. 2016, 22, 7950.
AUTHOR INFORMATION
Corresponding Author
mhorie@mx.nthu.edu.tw
(28)Kitagawa, D.; Kobatake, S. Chem. Commun. 2015, 51, 4421.
ORCID
Masaki Horie: 0000-0002-7734-5694
Notes
The authors declare no competing financial interests.
ACKNOWLEDGMENT
ACS Paragon Plus Environment

Page 5 of 11
Journal of the American Chemical Society
1
2
3
Insert Table of Contents artwork here
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
5
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 11
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
83x33mm (300 x 300 DPI)
ACS Paragon Plus Environment

Page 7 of 11
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
79x62mm (300 x 300 DPI)
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 11
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
83x95mm (300 x 300 DPI)
ACS Paragon Plus Environment

Page 9 of 11
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
83x82mm (300 x 300 DPI)
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 10 of 11
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
83x115mm (300 x 300 DPI)
ACS Paragon Plus Environment

Page 11 of 11
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
66x113mm (300 x 300 DPI)
ACS Paragon Plus Environment