Polarity dependent photoisomerization of ether substituted azodyes: Synthesis and photoswitching behavior

Article abstract of DOI:10.1016/j.saa.2015.05.027

Two new ether substituted azodyes were synthesized and characterized by different spectral analysis such as ¹H NMR, ¹³C NMR, FTIR and UV/Vis. Synthesized compounds were used to study the photoisomerization phenomenon by using UV-Vis

Full text of DOI:10.1016/j.saa.2015.05.027

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 875–880
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Polarity dependent photoisomerization of ether substituted azodyes:
Synthesis and photoswitching behavior
Gan Siew Mei a, Pearl Zynia Fernandes a,b, A.R. Yuvaraj a, M.R. Lutfor a, Gurumurthy Hegde c,
⇑
a Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, 26300, Gambang, Kuantan, Malaysia
b Department of Chemistry, National Institute of Technology, Karnataka, Mangalore, India
c BMS R and D Centre, BMS College of Engineering, Basavanagudi, Bangalore, India
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
New ether based azobenzenes
showing photoswitching behavior.
Polarity plays dominant role.
Strong structure property relations
with respect to light.
ꢀ
ꢀ
+
N2Cl
-
NaNO2
OH
O
NH
N
O
2
HCl / 2 o
C
pH 9
N
ꢀ
Possible choice for optical storage
device.
O
Br
O
OH
N
O
N
K2CO3
II
HBr
O
N
O
H
N
I
a r t i c l e i n f o
a b s t r a c t
Article history:
Two new ether substituted azodyes were synthesized and characterized by different spectral analysis
such as 1H NMR, 13C NMR, FTIR and UV/Vis. Synthesized compounds were used to study the photoisomer-
ization phenomenon by using UV–Vis spectro-photometer. Interesting polarity dependent effect is
observed for the first time on these materials. Trans–cis (E–Z) and cis–trans (Z–E) conversion occurred
within 41 s and 445 min, respectively for both the compounds in solutions. Polarizing optical microscopy
studies revealed that there is no liquid crystal phase for both the compounds. The dramatic variation in
the optical property is speculated to be the polarity of the chemical species. These derivatives are useful
to fabricate optical data storage devices.
Received 4 December 2014
Received in revised form 30 April 2015
Accepted 10 May 2015
Available online 16 May 2015
Keywords:
Photoisomerization
Polarity
E/Z isomers
Back relaxation
Azodyes
Ó 2015 Elsevier B.V. All rights reserved.
Introduction
molecular arrangement in chemical species which contains chro-
mophores [1–3]. Particularly, it is possible to store the data by
The optical storage device is the data storage device, in which
the information will be stored by light illumination. In other words,
data storage could be done by photo-induced phenomenon. Tacitly,
the photo-induced phenomenon is one of the blooming fields of
research in modern physics. The incident UV light changes the
changing the molecular alignment by illuminating UV light in stor-
age devices (around 365 nm, corresponding to the
p–
p⁄ excitation
of the azo group). The mechanism of data storage involves the E/Z
isomerization of light sensitive chromophoric substituent groups
[3–6]. Energetically more stable E-form isomerizes to give Z-form
when UV light is shined on the system [7]. Moreover, back relax-
ation may take place in most of the system by two important ways,
such as (i) irradiating UV light with 400–500 nm wavelength range
and (ii) keeping the system in the dark place or thermal back
⇑
Corresponding author at: BMS R and D Centre, BMS College of Engineering,
Basavanagudi, Bangalore, India.
E-mail address: murthyhegde@gmail.com (H. Gurumurthy).
http://dx.doi.org/10.1016/j.saa.2015.05.027
1386-1425/Ó 2015 Elsevier B.V. All rights reserved.

876
S.M. Gan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 875–880
relaxation. Here, the thermal back relaxation is one of the interest-
ing properties in light induced phenomenon.
dilute hydrochloric acid (50 ml of water and 22 ml conc.
hydrochloric acid) was added and the mixture was cooled to about
2 °C by using ice bath. Sodium nitrite (0.084 mol, 1 equi.) was dis-
solved in water (20 ml) and it was added drop-wise to the cooled
mixture and stirred for 1 h. Phenol (0.0813 mol, 0.9 equi.) was dis-
solved in an acetone/water mixture (300 ml/300 ml), then it was
chilled to 2 °C and added to the diazotized mixture. The mixture
was stirred with pH 9 by adding sodium hydroxide solution.
After 4 hours, about 800 ml of water was added and the mixture
was made slightly acidic (pH < 3) with dilute hydrochloric acid
for precipitation of the product and the precipitate was collected
by filtration. The product was recrystallized twice from methanol.
A reddish yellow colored solid; Rf = 0.4 (40% ethyl acetate – Pet
ether); yield: 65%; IR (KBr pellet) mmax in cmꢁ1: 3322, 1602, 1484,
1248, 1140, 829; 1H NMR (500 MHz, acetone-d6): d 7.82 (d,
J = 8.6 Hz, 2H, Ar), 7.76 (d, J = 8.6 Hz, 2H, Ar), 7.97 (d, J = 6.9 Hz,
4H, Ar), 6.93 (d, J = 8.7 Hz, 2H, Ar), 5.0 (s, 1H, OH), 3.73 (t, 3H,
Generally, azo group is a chromophoric group and it is showing
interesting behavior with the UV light [8–10]. Mainly, photoiso-
merization is peculiar property of azodyes. The photo-switching
behavior of azo dyes with different molecular structure and the
functional groups was studied and reported by Gurumurthy et al.
[11]. Further, the polarity of the functional groups also plays an
important role in the photoisomerization phenomenon [12,13].
The optical activity of the light sensitive compounds is increases
due to the enhancement of polarity [14], comparatively less energy
is sufficient for photo-excitation for polar molecules. In other
words, the polarity of the molecules facilitates the photoisomeriza-
tion of photoreactive species [15]. Moreover, the polarity and
hydrogen bonding effect vary the dipole moment of the molecular
system and polarity may boost the photosensitivity in isomeriza-
tion [16–18]. Shakir et al. proved that the protic solution showed
higher light sensitivity than aprotic solution [16]. It has been
reported that the rate of E–Z isomerization is directly related to
internal polarity and potential energy required for the photoiso-
merization of the azobenzene backbone [19]. In this case, polarity
arises due to presence of hydroxyl and ether forms in two different
molecular system. Clearly, the light induced isomerization deter-
mines photo-physical properties of the molecules. Consequently,
one can enhance the light sensitivity of azodyes by synthesizing
azodyes by considering the strategy of polarization [20–23].
The present investigation is mainly describes the synthesis and
E/Z isomerization of ether substituted new azo dyes. Interestingly,
time of back relaxation of the synthesized azo dyes were varied
with respect to the polarity of the molecules. These compounds
are good candidates to fabricate the optical storage display device.
OCH3); 13C NMR (100 MHz, CDCl3):
d 55.9, 115.01, 116.21,
124.01, 124.41, 145.01, 145.30, 160.21, 162.90.
A general procedure to prepare ether mesogens (2)
Compound-I (7.40 mmol, 1 equi.) was dissolved in dry acetone
(60 ml), allyl bromide (9.0 mmol, 1.2 equi.), potassium carbonate
(9.00 mmol, 1.2 equi.) and a catalytic amount of potassium iodide
(20 mg) was refluxed for 24 h under argon atmosphere. The mix-
ture was poured into ice-cold water and acidified with dilute
hydrochloric acid (pH < 5). The precipitate was filtered off and
was crystallized from methanol:chloroform (10:2).
A bright yellow colored solid; Rf = 0.3 (40% ethyl acetate – Pet
ether); yield: 65%; IR (KBr pellet) mmax in cmꢁ1: 2922, 2862, 1642,
1601, 1497, 1242, 1132, 829; 1H NMR (500 MHz, acetone-d6): d
7.83 (d, J = 8.5 Hz, 2H, Ar), 7.76 (d, J = 8.4 Hz, 2H, Ar), 7.98 (d,
J = 6.7 Hz, 4H, Ar), 6.92 (d, J = 8.6 Hz, 2H, Ar), 6.02 (m, 1H, ethylene),
5.42 (d, J = 16.2 Hz, 1H, ethylene), 5.34 (d, J = 10.2 Hz, 1H, ethylene),
4.60 (d, J = 4.8 Hz, 2H, OCH2), 3.72 (t, 3H, OCH3).
Experimental details
Materials and methods
Sodium nitrite (BDH), 4-methoxyaniline (Fluka), phenol
(Merck), potassium carbonate (Fluka), allyl bromide (Fluka), hydro-
bromic acid (Fluka) and silica gel-60 (Merck) were used as
received. Acetone was refluxed over phosphorus pentoxide
(Merck) and dichloromethane was refluxed over calcium hydride
and both were distilled out before use. Other solvents and
chemicals were used without further purification.
The scheme for the synthesis is given in the Fig. 1. The proce-
dures were initially studied from the earlier reported papers
[10,11] and modified the procedures according to the scheme.
A general procedure for the demethylation of hydroxyl group (3)
Demethylation of the compound-II by using hydro-bromic acid
yielded the phenolic compound. Compound-II (2.5 mmol, 1 equi.)
was dissolved in dichloromethane (100 ml) and hydro-bromic acid
(3.5 mmol, 1.2 equi.) was added drop-wise and the reaction was
maintained under argon atmosphere. The reaction mixture was
slowly poured into distill water. The product was extracted with
diethyl ether (400 ml) and the organic extracts were washed with
sodium chloride solution. The solvent was removed under reduced
pressure and product was dried in vacuum at 50 °C.
A general procedure for the preparation of azo dyes (1)
A bright yellow colored solid; Rf = 0.3 (40% ethyl acetate – Pet
ether); yield: 82%; IR (KBr pellet) mmax in cmꢁ1: 2924, 2860,
1640, 1601, 1490, 1244, 1130, 824; 1H NMR (500 MHz,
Approximately 250 ml of methanol with 50 ml water was used
to dissolve the 4-methoxyaniline (0.084013 mol, 1 equi.) and
+ -
N2Cl
NaNO2
OH
O
O
NH
2
HCl / 2 oC
pH 9
O
N
Br
O
N
OH
N
O
N
K2CO3
II
HBr
O
N
HO
N
I
Fig. 1. The figure described the synthetic method used in this study.

S.M. Gan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 875–880
877
acetone-d6): d 7.82 (d, J = 8.5 Hz, 2H, Ar), 7.76 (d, J = 8.6 Hz, 2H, Ar),
7.97 (d, J = 6.8 Hz, 4H, Ar), 6.91 (d, J = 8.5 Hz, 2H, Ar), 6.01 (m, 1H,
olefinic), 5.41 (d, J = 16.4 Hz, 1H, olefinic), 5.32 (d, J = 10.1 Hz, 1H,
olefinic), 4.60 (d, J = 4.8 Hz, 2H, ether), 5.02 (s, 1H, phenolic).
The absorption spectra of compounds I and II are shown in Fig. 3.
Consequently, photoswitching studies were initially performed
on solutions and then with solid by using cells. It gives an idea of
the behavior of materials with respect to UV light and also these
results are indispensable for creating optical storage devices.
Fig. 4 depicts the E/Z isomerization absorption spectra of
compound-I (Fig. 4a and b) and II (Fig. 4c and d) before and after
UV illumination. The absorption spectra of compound were studied
using chloroform (CHCl3) as solvent and concentration of the
solution was fixed at C = 1.1 ꢂ 10ꢁ5 mol Lꢁ1. The strong absorbance
Sample preparation
The structures of the intermediates and desired products were
confirmed by spectroscopic methods: IR spectra were recorded
using a ‘‘Perkin Elmer (670) FTIR spectrometer’’ and 1H NMR
(400 MHz), 13C NMR (100 MHz) by Bruker. The photo-switching
study was performed by recording UV/Vis absorption spectra
using a UV–Visible spectrophotometer obtained from ‘‘Ocean
Optics (HR2000+)’’. For photo-switching studies in solutions,
photo-switchable azodyes were dissolved in chloroform at concen-
trations C = 1.1 ꢂ 10ꢁ5 mol Lꢁ1. Photoisomerization of these com-
pounds were investigated by illuminating with an ‘‘OMNICURE
S2000 UV’’ source equipped with a 365 nm filter and heat filter
(was used to avoid heat radiations arising from the source to the
sample). Photoswitching studies were performed also in solid cells
where guest azodyes were mixed with host liquid crystals at
required ratio. The mixture is filled using capillary method in a pre-
viously prepared ITO coated cells with unidirectionally rubbed
in the UV region at 357.55 nm corresponds to
p–
p⁄ transition of
the E isomer (trans isomer) and a very weak absorbance in the vis-
ible region at ꢃ450 nm represents n–p⁄ transition of the Z isomer
(cis isomer).
The photo-switching property of compound-I and II were inves-
tigated with UV light illumination of intensity 5.860 mW/cm2. The
compounds were illuminated with UV light having 365 nm filter
and heat filter, at different time intervals and immediately the
absorption spectra were recorded. The absorption maxima were
decreased due to E/Z photoisomerization, which leads to E isomer
being transformed into the Z isomer. The photosaturation of the
compound-I was found at 40.34 s (Fig. 4a) whereas, the back relax-
ation was found at 444.14 min (Fig. 4b), compound II was photo-
saturated at 22.4 s (4c) whereas, the back relaxation was found
at 329 min (4d).
polyimide layers. Cell thickness is fixed around 5 lm.
Fig. 5 shows the E–Z and Z–E isomerization of compounds-I
(Fig. 5a) and II (Fig. 5b) as a function of exposure time, the peak
absorption values with different exposure times were recorded.
The curve showed that the phase involved E–Z photoisomerization
occurs within 41 s of exposure time whereas, the back relaxation
Result and discussion
Mesomorphic properties
The mesomorphic properties of the compounds was studied
using polarized optical microscopy (POM). The synthesized
compounds have two benzene rings with the terminal ether and
phenolic –OH group.
The POM of the compounds was measured at a rate of
2 °C min ꢁ1. Fig. 2 showing the crystalline phase of the compound
I (a) and II (b) at 158 °C and 150.4 °C. There was no special meso-
phases observed in both the compounds. So, these compounds do
not show the liquid crystalline behavior. However, the compounds
I and II were reached the isotropic phase at 185 °C and 193 °C,
respectively.
357.55nm
I
1.0
0.8
0.6
0.4
0.2
II
Photoswitching properties
300
350
400
(nm)
450
500
Photo-switching studies of our two synthesized azodyes
showed exactly similar absorption spectra and the peak is at
357.55 nm, due to their similar molecular structures. The only dif-
ference between two compounds is the functional groups at one of
the terminal, which are responsible for polarity of the compounds.
λ
Fig. 3. The absorption spectra of I and II was measured with the solutions at
C = 1.1 ꢂ 10ꢁ5 mol Lꢁ1 by using UV–Vis spectrophotometer. Chloroform was used as
solvent.
Fig. 2. The POM image of the compound I (a) and II (b) was captured at 158 °C and 150.4 °C at crystalline phase. The mesophases were not observed for both the compounds I
and II.

878
S.M. Gan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 875–880
0.1 mins
1 mins
357.55nm
357.55nm
0.0sec
0.4 sec
2.5sec
3.3sec
4.5sec
6.5sec
9.1sec
25.1sec
25.5 sec
I
I
1.0
0.8
0.6
0.4
0.2
1.0
0.8
0.6
0.4
0.2
6 mins
16 mins
34 mins
52 mins
72 mins
94 mins
121 mins
168 mins
254 mins
318 mins
445 mins
(b)
(a)
300
350
400
450
500
300
350
400
450
500
λ
(nm)
λ
(nm)
1.2
No UV
0sec
0 sec
357.55 nm
357.55 nm
1.0
0.8
0.6
0.4
0.2
II
0.4sec
1sec
II
5sec
1.0
0.8
0.6
0.4
0.2
10sec
1min
2min
50min
78min
133min
168min
222min
329min
1.8sec
2.7sec
3.2sec
4.9sec
6.3sec
8.4sec
9.3sec
14sec
22.4sec
(c)
(d)
350
400
450
500
350
400
450
500
550
λ
(nm)
λ
(nm)
Fig. 4. E to Z conversion and Z to E photoisomerization of I (a and b) and II (c and d) was studied in solution. The curves showed that the phase involved E–Z
photoisomerization occurs within 41 s of exposure time whereas, the back relaxation occurs at 444.14 min and 329 min for the compounds I and II, respectively.
Time of back relaxation (min)
UV irradiation (secs)
0
5
10
15
0
100
200
300
400
1.0
0.8
0.6
0.4
0.2
1.0
0.8
0.6
0.4
0.2
(b)
I (357.55nm)
(a)
1.0
0.8
0.6
0.4
0.2
1.0
0.8
0.6
0.4
0.2
II (365.55nm)
I (357.55nm)
II (357.55nm)
0
100
Time of2b0a0ck rela3x0a0tion (m4in00)
0
10
20
30
40
UV irradiation (secs)
Fig. 5. The peak absorbance of I (a) and II (b) was considered with respect to the function of time interval for E–Z and Z–E conversion.
occurs at 444.14 min and 329 min for the compounds-I and II,
respectively. The difference in the back relaxation is due to the dis-
similar polarity between the compounds. However, the photosatu-
ration of both the compounds are not varied with the polarity. So
that the time of photosaturation is almost similar for the
compounds-I and II. Hence, it is clear that the time of photosatura-
tion depends on molecular structures and it is independent from
the polarity or nature of functional groups.
the recovery time will be high in the chemical species containing
polar substituent groups.
The extent of isomerization was determined using the
classical equation and tabulated as Table 1. The conversion
efficiency (CE) which is also called as extent of isomerization of
the E/Z photoisomerization is estimated from the below equation
[24].
Aðt0Þ ꢁ Aðt1Þ
Here, it is clear that the time interval of thermal back relaxation
increase with increase in polarity of the molecules. In other words,
E ¼
ꢂ 100%
Aðt0Þ

S.M. Gan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 875–880
879
5 mW/cm2
1.2 mW/cm2
0.9
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
442 mins
462 mins
400
0
100
200
300
400
500
0
100
200
300
500
Back Relaxation (minutes)
Back Relaxation (minutes)
8.7 mW/cm2
10.5 mW/cm2
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
228 mins
361 mins
0
100
200
300
400
500
0
100
200
Back Relaxation (minutes)
Back Relaxation (minutes)
15.4 mW/cm2
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
212 mins
0
100
200
Back Relaxation (minutes)
Fig. 6. Thermal back relaxation or Z–E transformation was measured for compound I by keeping the solution for long time in dark place. The solution was previously
illuminated with UV light of different intensities.
Earlier, it was reported that back relaxation reduces with
increase the intensity [8]. Concurrently, the results of these two
samples agreed with the previous results.
Table 1
The extent of isomerization or conversion efficiency of I and II was measured by using
classical equation and given here.
The photosaturation value also decreased with the rise in inten-
sity as shown in the Fig. 7. Here also, the photosaturation is inver-
sely proportional to the intensity of light exposure. Clearly, one can
easily observe the photoactive behavior of the azodyes with varia-
tion of intensity.
Compounds
Conversion efficiency (CE) (%)
I
II
91.01
87.97
Spectral investigations on solid cell were done for the sample-I,
since it showed good conversion efficiency of E/Z in solution as
compared to sample-II and were shown in Fig. 8. The commercial
liquid crystal is used as host material and it was mixed with guest
material ‘I’. The cell was constructed by pre-coated ITO glass plates
with polyimide and unidirectionally rubbed.
5% of compound-I (guest molecules) was dissolved in 95% of
commercial liquid crystal ‘‘MLC6873-100’’ (host molecules).
Mixture was capillary filled in the previously prepared cell via cap-
where Aðt0Þ is absorbance before UV and Aðt1Þ is absorbance after
UV.
The CE values are almost same. There is no large gap between
two values, because of the similar chemical structure of the com-
pounds. Even though extent of isomerization decreased due to
the decrease in polarity of the chemical species, one can enhance
the conversion efficiency of the material by adding highly polar
substituent parent compound.
Fig. 6 shows the fastness of the back relaxation time, for the
previously illuminated solutions with different intensities.
Clearly, the intensity of the UV light is inversely proportional to
the time of Z–E conversion.
illary action, at isotropic phase (ꢃ100 °C) with the cell gap 5
lm.
Similar to the solution illumination, solid cell was also illuminated
with UV light of wavelength 365 nm with heat filter and the pho-
tosaturation was found at 6.1 s and complete thermal back relax-
ation was observed at 450 min with intensity 5.860 mW/cm2.

880
S.M. Gan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 875–880
photoisomerization. Extent of isomerization decreases due to the
I (357.55nm)
decrease in polarity of the chemical species. However, these com-
pounds are suitable for photochromism studies. It is clear that the
effect of polar substituent group is considerable in the study of
optical properties of the azodyes. The photoswitching properties
of compounds showed E–Z and Z–E isomerization within 41 s
and 445 min in solutions, respectively. Liquid crystal phases were
not absorbed in case of both the reported compounds. Tacitly,
the photoswitching behavior of these azodyes may be suitably
exploited in the field of optical data storage devices and in molec-
ular switches.
500
400
300
200
Acknowledgement
2
4
6
8
10
12
14
16
UV Intensity (mW/cm2)
Gan Siew Mei and Yuvaraj A R would like to thank the Ministry
of Science and Technology Industry (MOSTI) in the form of
e-Science grant RDU 130503.
Fig. 7. The photosaturation of sample I with respect to the different intensities for
E–Z isomerization was measured.
References
Back Relaxation (minutes)
[1] A.R. Yuvaraj, T.N.W. Chan, P.G. Yit, H. Gurumurthy, Spectrochim. Acta A Mol.
Biomol. Spectrosc. 135 (2014) 1115.
0
100
200
300
400
[2] I.C. García, M. Marazzi, L.M. Frutos, D. Sampedro, RSC Adv. 3 (2013) 6241.
[3] A.A. Beharry, G.A. Woolley, Chem. Soc. Rev. 40 (2011) 4422.
[4] R. Dong, B. Zhu, Y. Zhou, D. Yan, X. Zhu, Polym. Chem. 4 (2013) 912.
[5] C.T. Imrie, P.A. Henderson, Curr. Opin. Colloid Interface Sci. 7 (2002) 298.
[6] R. Aneela, P.L. Praveen, D.P. Ojha, J. Mol. Liq. 166 (2012) 70.
[7] J.W. Goodby, B. Pfannemüller, W. Welte, E. Chin, J.W. Goodby, Liq. Cryst. 33
(2006) 1229.
[8] M. Šepelj, A. Lesac, U. Baumeister, S. Diele, H.L. Nguyen, D.W.J. Bruce, Mater.
Chem. 17 (2007) 1154.
[9] G. Hegde, V.M. Kozenkov, V.G. Chigrinov, H.S. Kwok, Mol. Cryst. Liq. Cryst. 507
(2009) 41.
UV ON
UV Off
1.0
0.8
0.6
0.4
0.2
1.0
0.8
0.6
0.4
0.2
[10] M.R. Lutfor, S. Kumar, C. Tschierske, G. Israel, D. Ster, G. Hegde, Liq. Cryst. 36
(2009) 397.
[11] A.R. Yuvaraj, S.W. Gan, K. Ajaykumar, M.M. Yusoff, H. Gurumurthy, RSC Adv. 4
(2014) 50811.
[12] J.W. Goodby, V. Görtz, S.J. Cowling, G. Mackenzie, P. Martin, D. Plusquellec, J.
Fitremann, Chem. Soc. Rev. 2007 (1971) 36.
[13] G.Y. Yeap, W.S. Yam, M.M. Ito, Y. Takahashi, Y. Nakamura, M.W.A. Kamil, E.
Gorecka, Liq. Cryst. 34 (2007) 649.
0
1
2
3
4
5
6
Time of Irradiation (secs)
[14] C.B. Andrew, H. Anthony, C.J. McAvoy, Chem. Soc. Faraday Trans. 94 (1998)
519.
[15] J.M. Hicks, M.T. Vandersall, E.V. Sitzmann, K.B. Eisenthal, Chem. Phys. Lett. 135
(1987) 413.
[16] T. Shakir, H. Abdel, H. Mahmoud, K. Abdel, J. Phys. Chem. 92 (1988) 4324.
[17] F. Serra, E.M. Terentjev, Macromolecules 41 (2008) 981.
[18] H. Görner, D.S. Frohlinde, J. Photochem. 8 (1978) 91.
[19] C. Poloni, W. Szyman´ ski, L. Hou, W.R. Browne, B.L. Feringa, Chem. A Eur. J. 20
(2014) 946.
Fig. 8. The peak absorbance of the E–Z and Z–E isomerization with respect to time
interval were considered. Then, compared the photosaturation and thermal back
relaxation of compound I by using solid cell. Here, guest–host method is employed
to fabricate the cell. 95% of host material (MLC 6873-100, commercial LC) was
mixed with 5% of the guest material (compound I). The mixture was filled in
polyimide coated, rubbed cells.
[20] W.A. Velema, W. Szymanski, B.L. Feringa, J. Am. Chem. Soc. 136 (2014) 2178.
[21] G.S. Kumar, D.C. Neckers, Chem. Rev. 1989 (1915) 89.
[22] N.K. Joshi, M. Fuyuki, A. Wada, J. Phys. Chem. B 2014 (1891) 118.
[23] D.H.M. Bandara, C.B. Shawn, Chem. Soc. Rev. 2012 (1809) 41.
[24] G. Barbero, L.R. Evangelista, L. Komitov, J. Phys. Rev. E 65 (2002) 041719.
There is a similarity in the chemical structures of both the com-
pounds. Also, they showed similar characteristics. Hence, these
two compounds are suitable to fabricate the data storage devices.
Conclusion
Two new ether substituted azodyes with different functional
groups were synthesized. The polar molecules play main role in