Thermochromic Properties of Fluorans in Solid State and Application in Acrylic Fiber as Thermal Indicator
Kim et al.
3.5. FT-IR Spectroscopic Studies
constructed using a chiral azo-calix[4]arene functionalized silicon
surface. Chemical Communications, 54(24), pp.2978–2981.
3. Irie, M. and Morimoto, M., 2018. Photoswitchable turn-on mode
fluorescent diarylethenes: Strategies for controlling the switch-
ing response. Bulletin of the Chemical Society of Japan, 91(2),
pp.237–250.
4. Lv, J., Abbas, S.C., Huang, Y., Liu, Q., Wu, M., Wang, Y.
and Dai, L., 2018. A photo-responsive bifunctional electrocatalyst
for oxygen reduction and evolution reactions. Nano Energy, 43,
pp.130–137.
5. Crenshaw, B.R., Burnworth, M., Khariwala, D., Hiltner, A., Mather,
P.T., Simha, R. and Weder, C., 2007. Deformation-induced color
changes in mechanochromic polyethylene blends. Macromolecules,
40(7), pp.2400–2408.
6. Lim, S.J., An, B.K., Jung, S.D., Chung, M.A. and Park, S.Y., 2004.
Photoswitchable organic nanoparticles and a polymer film employing
multifunctional molecules with enhanced fluorescence emission and
bistable photochromism. Angewandte Chemie International Edition,
43(46), pp.6346–6350.
FT-IR was recorded to confirm the structural changes in
TC1 and TC2, the spectra was measured at different tem-
ꢀ
peratures (20 and 40 C) (Fig. 7). The measured FT-IR
spectra showed a peak in the range of 1760 cm−1 for TC1
and TC2 which agrees with C O stretching frequency
[31, 32] for theꢀ fluoran molecule (colorless) in the heat-
ingꢀstate at 40 C, and for the sample in cooled state at
20 C of fluoran moiety (orange color) the peak appeared
at 1738 cm−1. The results obtained from the spectra reveals
that the shift in the peak position validate to the transfor-
mation of structure in the thermochromic material both in
heating and cooling condition, the frequency shift towards
lower region for the C O group for the orange colored
sample due to ring opening of lactone ring results in car-
boxylate group formation which further gets protonation
easier [31].
7. Kishimura, A., Yamashita, T., Yamaguchi, K. and Aida, T., 2005.
Rewritable phosphorescent paper by the control of competing kinetic
and thermodynamic self-assembling events. Nature Materials, 4(7),
pp.546–549.
3.6. Application as Thermal Indicator
Inspired by the thermal color changes of the synthesized
fluoran moiety TC1 and TC2, we prepared a thermal indi-
cator for the real time application using TC1. TC1 com-
posite was applied to filter paper as well as in acrylic
fiber, for this purpose the composite was prepared by mix-
ing 5 wt.% of TC1, 2.5 wt.% bisphenol-A and 92.5 wt.%
low melting solvent methyl stearate were mixed homoge-
nously, and applied to filter paper and acrylic fiber and
color change on heating and cooling was checked thor-
oughly in repeated manner to confirm the reversibility in
color change. In this process, TC1 generates orange color
8. Zhu, C.F. and Wu, A.B., 2005. Studies on the synthesis and ther-
mochromic properties of crystal violet lactone and its reversible ther-
mochromic complexes. Thermochimica Acta, 425(1–2), pp.7–12.
9. Meiqin, S., Yun, S. and Qiyu, T., 1995. Synthesis of fluoran dyes
with improved properties. Dyes and Pigments, 29(1), pp.45–55.
10. Carmona, N., Bouzas, V., Jimenez, F., Plaza, M., Perez, L., Gar-
cia, M.A., Villegas, M.A. and Llopis, J., 2010. Cobalt(II) environ-
ment characterization in sol–gel thermochromic sensors. Sensors and
Actuators B: Chemical, 145(1), pp.139–145.
11. Chen, X. and Yoon, J.A., 2011. A thermally reversible tempera-
ture sensor based on polydiacetylene: Synthesis and thermochromic
properties. Dyes and Pigments, 89(3), pp.194–198.
12. Wu, Z., Pan, K., Mo, S., Wang, B., Zhao, X. and Yin, M., 2018.
Tetraphenylethene-induced free volumes for the isomerization of
spiropyran toward multifunctional materials in the solid state. ACS
Applied Materials & Interfaces, 10(36), pp.30879–30886.
13. Mo, S., Meng, Q., Wan, S., Su, Z., Yan, H., Tang, B.Z. and Yin, M.,
2017. Tunable mechanoresponsive self-assembly of an amide linked
dyad with dual sensitivity of photochromism and mechanochromism.
Advanced Functional Materials, 27(28), pp.1701210–1701219.
14. Wan, S., Ma, Z., Chen, C., Li, F., Wang, F., Jia, X., Yang, W.
and Yin, M., 2016. A supramolecule-triggered mechanochromic
switch of cyclodextrin-jacketed rhodamine and spiropyran deriva-
tives. Advanced Functional Material, 26(3), pp.353–364.
15. Kolmakov, K., Belov, V.N., Bierwagen, J., Ringemann, C., Muller, V.
and Eggeling, C., 2010. Red-emitting rhodamine dyes for fluores-
cence microscopy and nanoscopy. Chemistry A European Journal,
16(1), pp.158–166.
ꢀ
ꢀ
at 20 C and becomes colorless when heated to 40 C
(Fig. 8) and Plausible mechanism of three component mix-
ture in thermal indicator upon heating and cooling process
has been shown in Figure 9.
4. CONCLUSION
In summary, fluoran based thermochromic material was
synthesized, and its color changing property in solid as
well as liquid state was successfully demonstrated. These
fluoran moieties TC1 and TC2 have the lactone unit in the
structure tend to show a promising material for leuco dyes.
A reversible color change from colorless to orange was
obtained when controlled the temperature between heat-
ing and cooling process. The composite prepared using
TC1, bisphenol-A and methyl stearate has been success-
fully applied in filter paper as well as acrylic fiber showed
16. Wu, L. and Burgess, K., 2008. Synthesis and spectroscopic prop-
erties of rosamines with cyclic amine substituents. The Journal of
Organic Chemistry, 73(22), pp.8711–8718.
17. Dahms, K., Batsanov, A.S. and Bryce, M.R., 2010. An unusual syn-
thesis of a spirothioxanthene derivative. Tetrahedron Letters, 51(50),
pp.6605–6607.
ꢀ
reversible color change between 20 and 40 C which can
be used in real time as a thermal indicator.
18. Inouye, M., Tsuchiya, K. and Kitao, T., 1992. New thermo-response
dyes: Coloration by the claisen rearrangement and intramolecular
acid-base reaction. Angewandte Chemie International Edition, 31(2),
pp.204–205.
19. Garner, R. and Petitpierre, J.C., 1982. Copying material employing
fluoran color formers. United States Patent No., 4, 349, 218.
20. Kim, G.W., Kim, Y.C., Ko, I.J., Park, J.H., Bae, H.W., Lampande, R.
and Kwon, J.H., 2018. High-performance electrochromic optical
shutter based on fluoran dye for visibility enhancement of augmented
References and Notes
1. Seki, T., 2018. A wide array of photoinduced motions in molecular
and macromolecular assemblies at interfaces. Bulletin of the Chem-
ical Society of Japan, 91(7), pp.1026–1057.
2. Pang, H., Xu, P., Li, C., Zhan, Y., Zhang, Z., Zhang, W., Yang, G.,
Sun, Y. and Li, H., 2018. A photo-responsive macroscopic switch
8018
J. Nanosci. Nanotechnol. 19, 8013–8019, 2019