Multifunctional properties of a star-shaped triphenylamine-benzene-1,3,5-tricarbohydrazide fluorescent molecule containing multiple flexible chains

Article abstract of DOI:10.1039/d0cc05538g

A star-shaped triphenylamine-benzene-1,3,5-tricarbohydrazide molecule with a twisted molecular conformation was found to display amazing multifunctional optical properties. The design of peripheral triphenylamine units and a central benzene connected with hydrazide groups leads to the formation of rare polymorphic properties in the presence of multiple flexible chains. Two polymorphs with different fluorescence colors exhibited bathochromic mechanofluorochromic activities with high contrast due to a crystalline-to-amorphous transition.

Full text of DOI:10.1039/d0cc05538g

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Multifunctional properties of a star-shaped triphenylamine-
benzene-1,3,5-tricarbohydrazide fluorescent molecule containing
multiple flexible chains
Xin Feng,‡ Yating Chen,‡ Yunxiang Lei, Yunbing Zhou, Wenxia Gao,* Miaochang Liu,
Xiaobo Huang* and Huayue Wu
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
A
star-shaped triphenylamine-benzene-1,3,5-tricarbohydrazide organic MFC-active compounds containing multiple flexible amide
molecule with a twisted molecular conformation was found to chains have been reported,6 to the best of our knowledge, this kind
display amazing multifunctional optical properties. The design of of compounds with both mechanofluorochromism and
peripheral triphenylamine units and central benzene connected polymorphism are not reported, which is still challenging and
with hydrazide groups leads to the formation of rare polymorphic worthy of further study.
property in the presence of multiple flexible chains. Two
In this work, a star-shaped triphenylamine-benzene-1,3,5-
polymorphs with different fluorescence colors exhibited tricarbohydrazide molecule (TBTCH, Fig. 1A) was designed and
bathochromic mechanfluorochromic activities with high contrast synthesized, in which the peripheral rigid triphenylamine (TPA)
due to a crystalline-to-amorphous transition.
groups and the central benzene ring are connected with amide
groups and C=N bonds. Our design ideas are as follows: (1) the rigid
structures in the center and the periphery can weaken the disorder
caused by a large number of flexible chains and keep the target
compound with appropriate crystallization ability; (2) the TPA unit
has propeller-like conformation and strong electron-donating
ability, which is beneficial to obtain aggregation-induced emission
(AIE), strong solid-state emission, and thus possible MFC activity; (3)
the flexible chains containing hydrazide groups can be used to
regulate the molecular packing modes by intermolecular N–H···O,
N–H···N, or C–H···O hydrogen bonds, and the varied balance of the
non-covalent interactions between molecules is advantageous to
the generation of polymorphism, moreover, the existence of
numerous hydrogen bonds also provides the basis for the formation
of organic gel between fluorescent molecules.7 As expected, TBTCH
exhibits interesting multifunctional optical properties containing
both polymorphism and mechanofluorochromism.
The target compound TBTCH was prepared from a simple two-
step procedure using commercially available trimethyl benzene-
1,3,5-tricarboxylate as the starting material according to Scheme S1
(ESI†), and the detailed experimental methods are provided in the
supporting information. Considering the strong electron-donating
ability of TPA unit, TBTCH could be thought as a D-π-A-type
molecule with the electron cloud flowing from the periphery to the
center. The absorption and fluorescence spectra in various organic
solvents with the increasing polarity, such as toluene, chloroform,
dichloromethane (DCM), dimethyl sulfoxide (DMSO), acetonitrile
(MeCN), and methanol, were investigated (Fig. S1 and Table S1,
ESI†). The maximum absorption wavelength of this compound in
different solvents was in the range of 373-385 nm, indicating that
the polarity of the solvent had little influence on the absorption
Organic mechanofluorochromic (MFC) materials, which can exhibit
the changes of solid-state fluorescence colors and intensities under
the stimulation of external pressure, have recently attracted
considerable attention owing to the wide applications in the fields
of chemosensors, rewritable optical media, memory devices, and
security systems.1 On the view of macroscopic, the MFC activities
are often attributed to morphological changes.2 Therefore, the
crystallization ability of the candidate compounds is very important
because only by obtaining the original sample with crystalline state
can it be possible to realize the transition from a crystalline state to
an amorphous state or from one crystalline state to another.
Especially, the realization of the latter depends to a great extent on
the polymorphic property of the compounds, which is reported to
exist in one-third of organic compounds, but its discovery strongly
depends on experimental experiences rather than prediction.3 Up
to now, most of organic compounds with MFC properties have been
reported to focus on rigid and twisted molecular structures,4 and
flexible chains are confirmed to be used to regulate their packing
modes.5 However, flexible chain is a double-edged sword because
the increase of its number will easily lead to the disorder of organic
molecules and greatly reduce their crystallization abilities, which
are not advantageous to the generation of the compounds with
MFC and/or polymorphic properties. Therefore, although some
a.College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou,
325035, P. R. China. E-mail: wenxiag@wzu.edu.cn; xiaobhuang@wzu.edu.cn
†
Electronic Supplementary Information (ESI) available: Synthesis, characterization,
optical measurement and data, 1H NMR, 13C NMR, and crystal structures. CCDC
2020452-2020452. See DOI: 10.1039/x0xx00000x
‡ These authors contributed equally to this work
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wavelengths. However, the fluorescence spectrum exhibited an
obvious bathochromic shift from 442 nm in toluene to 518 nm in
methanol with a fluorescence color change from blue to yellow.
This result revealed that TBTCH displayed obvious solvatochromic
property. Based on the Lippert-Mataga equation,8 the effect of
solvent polarity on the photophysical properties was investigated.
The absorption maxima and emission maxima of TBTCH and solvent
polarity parameter in different solvents are collected in Table S1
(ESI†) and the Stokes shift (∆ν) against orientation polarizability (∆f)
was conducted. As depicted in Fig. S2 (ESI†), ∆ν has a positive linear
correlation with ∆f (R = 0.95), which revealed that the dipole
moments of the excited states of TBTCH were larger than those of
the ground states. Therefore, the solvatochromic properties of
TBTCH should be attributed that the solvent molecules with large
polarity effectively reduce the energy of excited states and enhance
the intramolecular charge transfer (ICT) effect.9
The absorption and fluorescence spectra of TBTCH in
tetrahydrofuran (THF)-water mixture were investigated the possible
AIE property. When water volume fraction (fw) was at 0-50%, the
maximum absorption wavelengths of the mixtures did not change
significantly and the fluorescence molecules should exist in free
form (Fig. S3a, ESI†). Correspondingly, the emission wavelengths of
the mixtures gradually red-shifted and the intensity decreased
gradually (Fig. 1B), which should be ascribed to the increase of the
polarity of the mixtures.10 However, when fw ≥ 60%, the maximum
absorption wavelengths of the mixtures obviously became larger,
and the absorption spectra became broad and upward-shifted,
which should be caused by the Mie scattering effect, revealing the
formation of aggregates.11 Correspondingly, the emission
wavelengths of the mixtures decreased gradually, and the intensity
increased gradually and reached the maximum value at fw = 90%,
which was about 7-fold higher than that in pure THF solvent (Fig.
S3b, ESI†). The emission behaviors of the mixtures at fw = 60-90%
should be dominated by the AIE effect by inhibiting the
intramolecular rotations and thus eliminating the non-radiative
energy loss.12
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DOI: 10.1039/D0CC05538G
fw
B
A
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
0
400 450 500 550 600 650 700
Wavelength (nm)
477 nm 498 nm
(c)
TBTCH-c
C
1.0
0.8
0.6
0.4
0.2
0.0
D
TBTCH-g
Cyan
(a)
(b)
Green
450 500 550 600 650 700
Wavelength (nm)
Fig. 1 (A) Chemical structure of TBTCH. (B) Fluorescence spectra of
TBTCH in THF-water mixtures with different fw at a concentration of 1 ×
10−5 mol/L. Insets: Inset: fluorescence photos at fw = 0%, 50%, and 90%
under 365 nm irradiation. (C) Image of gel under natural light (a) and
365 nm light (b), and SEM image of xerogel (c). (D) Fluorescence
spectra of TBTCH-c and TBTCH-g. Insets: fluorescence photos of the
single crystals of TBTCH-c and TBTCH-g under 365 nm irradiation.
shift of protons in aromatic rings with increasing the concentration
of gelator (Fig. S4b, ESI†), which further indicated the formation of
intermolecular π-π stacking interactions.15 Additionally, the
hydrogen-bond interactions seemed to play a key role in the three-
dimensional self-assembly of the gelator because numerous
hydrogen bonds were observed in the aggregated state of the
compound due to the presence of amino groups and carbonyl
groups in the chemical structure (see below).7
In particular, even if the presence of multiple flexible hydrazide
groups, two kinds of single crystals TBTCH-c and TBTCH-g could be
successfully obtained from
a
slow evaporation of the
1:5:5) mixture and the
DMSO/chloroform/methanol (v/v/v
=
DMSO/THF (v/v = 1:2) mixture, respectively. TBTCH-c emitted cyan
fluorescence at 477 nm with fluorescence quantum efficiency (ФF)
of 45.3%, while TBTCH-g emitted green fluorescence at 498 nm
with a ФF value of 29.2% (Fig. 1D and Table S2, ESI†). This result
indicated that TBTCH had polymorphic property. Compared with
TBTCH-g, TBTCH-c showed a higher ФF value, which was attributed
that TBTCH-c had a larger radiative rate constant (kf = 1.73×108 s-1)
and smaller non-radiative rate constant (knr = 2.09 ×108 s-1) than
TBTCH-g (kf = 1.64×108 s-1 and knr = 3.98 ×108 s-1) (Table S2, ESI†).
Upon grinding using mortar and pestle, green-emitting TBTCH-g
showed a 30 nm red shift in the emission spectrum from 498 nm to
528 nm, and transformed into yellow-emitting ground sample with
a decrease of ФF from 29.2% to 15.5%, revealing the MFC property
(Fig. 2A, Fig. 2C and Table S2, ESI†). The X-ray powder diffraction
(XRD) curves showed the crystalline structure was destroyed upon
grinding because the strong and sharp diffraction peaks
disappeared completely (Fig. S5a, ESI†). Furthermore, according to
the SEM experiments, large size columnar crystals of TBTCH-g were
obviously damaged under the grinding treatment (Fig. S6, ESI†).
Thus, the solid-state fluorescence color change was ascribed to the
transition from the crystalline state to the amorphous state. When
the ground sample was fumed using ethyl acetate (EA) vapor, the
resultant fumed sample exhibited a 22 nm blue shift in the emission
spectrum and emitted yellow-green fluorescence at λem = 506 nm
Furthermore, the gelation behavior of TBTCH was examined in
organic solvents. When the chloroform solution of TBTCH was
heated at 60°C and then cooled to room temperature, the gelator
could be obtained, which had excellent gelation ability with very
low critical gelation concentration of 0.27 wt%. The gelator showed
yellow color in appearance and emitted cyan fluorescence (Fig. 1C),
and turned into the solution after being heated, revealing good
thermo-reversibility. The sol-gel and gel-sol transitions were the
results of the assembly of three-dimensional network and the
disruption of non-covalent interactions within the gel network,
respectively. The assembly of three-dimensional network could be
observed in the scanning electron microscopy (SEM) image after
the gelator was dried (Fig. 1C), which was driven by the
hydrophobic interactions as well as hydrogen bonds and π-π
stacking interactions to immobilize a large volume of organic
solvent in the organogel.13 The fluorescence of the gelator
increased along with the increased gelator concentration, and the
intensity began to decrease once the concentration was higher than
25 μg/mL (Fig. S4a, ESI†). The decrease of fluorescence of the
gelator demonstrated the formation of π-π stacking interaction.14
1
The H NMR spectra of the gelator showed the gradual high field
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with a ФF value of 27.3%. For the fumed sample, considering that investigated the stacking arrangements and iVnietewrAmrtioclleeOcunllianer
only several broad and weak diffraction peaks (θ = 5.4°, 11.5° and interactions of these two compounds. As sDhOowI: 1n0.i1n03F9ig/.D30aCCa0n5d53F8igG.
16.3°) reappeared and the XRD curve could not completely recover S8a (ESI†), TBTCH-g and TBTCH-c both can be considered to be
to that of the original sample (Fig. S5a, ESI†), it should be the composed of the molecule pairs with reverse and dislocated
mixtures of crystalline and amorphous states. In view of TBTCH-c, stacking, and adopt very similar stacking arrangements. For TBTCH-
after being ground, the resultant sample emitted yellow-green g, the two molecules in pair are linked by the C–H···O bonds (2.497
fluorescence at λem = 512 nm with a ФF value of 28.3% (Fig. 2A, Fig. and 2.760 Å), N–H···O hydrogen bond (2.258 Å), and N–H···N
2D and Table S2, ESI†). However, the solid-state fluorescence color hydrogen bond (2.590 Å) (Fig. 3b), and the adjacent molecules of
of the ground sample could not recover to the original state by the different pairs are linked by the N–H···O hydrogen bond (2.184 Å)
common fumigation method. It should be pointed out that although (Fig. 3c). Additionally, due to the large space structure of this
the ground sample of TBTCH-c was very similar to the fumed molecule, the non-adjacent molecules can also be connected with
sample of TBTCH-g in the fluorescence colors and spectra, this each other by C–H···π (Ph) bonds (2.982, 3.311, and 3.495 Å)
sample was completely amorphous according to the XRD curve (Fig. between triphenylamine molecules which are close in space (Fig.
S5b, ESI†). By heating the TBTCH-c sample at 217°C for 1 h and then 3d). In view of TBTCH-c, the molecules in the single crystal are also
cooling to room temperature, the resultant annealed sample was stabilized by the corresponding C–H···O and C–H···π bonds, and N–
consistent with the fumed sample of TBTCH-g (Fig. 2A, Fig. 2C and H···O and N–H···N hydrogen bonds (Figs. S8b-S8d, ESI†). The
Table S2, ESI†). The conversion between TBTCH-g and TBTCH-c difference of the non-covalent interactions between TBTCH-g and
could only be achieved by the recrystallization process under the TBTCH-c is that the distances of the former are generally larger than
corresponding conditions. Considering that the reversibility of the the corresponding distances of the latter, revealing that the latter
MFC activity of the TBTCH-g sample, it could be developed as a has stronger non-covalent interactions and closer stacking. Another
rewritable optical medium (Fig. 2B). First, the TBTCH-g solid was proof is that the crystal lattice of TBTCH-c had a3slightly smaller
laid on the filter paper coated with commercial solid glue, and then volume and a slightly larger density (V = 2938.6 Å and d = 1.239
a hollow pattern model of animal was placed on the surface of Mg/m3) than that of TBTCH-g (V = 2945.1 Å3 and d = 1.236 Mg/m3)
TBTCH-g. The hollow part was ground with a metal spatula, and (Table S3, ESI†). Considering that these two polymorphs have a
then
a yellow animal picture was presented in the green nearly identical stacking pattern, compared with TBTCH-g, the blue-
background under the 365 nm irradiation, which had a high shifted emission and higher ФF value of TBTCH-c should be
contrast in color. After being fumed by EA vapor, the animal picture attributed to the more twisted conformation and stronger non-
disappeared.
covalent interactions.
Because the photophysical properties and MFC activities of the
Based on the results of the single-crystal structural analyses, the
fluorescent molecules are often related to their crystalline AIE activity and strong solid-state emission of TBTCH can be
structures,16 we first investigate the molecular conformations of explained as follows. In the pure solvent, the intramolecular free
TBTCH-g and TBTCH-c (Fig. S7, ESI†). For TBTCH-g, the dihedral rotations of phenyl rings around the carbon-carbon single bond
angles between the central phenyl ring (A) and the peripheral enhance the non-radiative relaxation process of the isolated
phenyl rings B, C, and D are 17.55o, 34.98o, and 35.95o, while the molecules and eliminate the emission. In the THF-water mixtures
corresponding dihedral angles in TBTCH-c are 18.02o, 35.16o, and with high fw value (60-90%), the non-covalent interactions caused
36.05o, respectively, which indicates that TBTCH-c has a more by the aggregation effectively restrict the intramolecular rotations
twisted molecular conformation than TBTCH-g. We further
(a)
(b)
(a)
(a)
(b)
B
A
(c)
(e)
(d)
(c)
(d)
(c)
(b)
N4-H4··· N8
498 nm 506 nm 528 nm
477 nm509 nm
512 nm
TBTCH-g
Ground
Fumed
TBTCH-c
Ground
Annealed (TBTCH-c)
C
D
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
C5-H5··· O3
C29-H29··· O3
N7-H7··· O1
N4-H4··· O3
(d)
450 500 550 600 650 700
Wavelength (nm)
450 500 550 600 650 700
Wavelength (nm)
H21 ··· π (Ph)
H22 ··· π (Ph)
H32 ··· π (Ph)
Fig. 2 (A) Fluorescence images of the solid samples of TBTCH under 365
nm irradiation: (a) TBTCH-g; (b) the ground sample of TBTCH-g; (c) the
fumed sample of TBTCH-g; (d) TBTCH-c; (e) the ground sample of
TBTCH-c. (B) A rewritable optical medium based on the surface of
TBTCH-g coated on filter paper upon grinding (write) and fuming
(erase). (C) Fluorescence spectra of TBTCH-g upon different conditions.
(D) Fluorescence spectra of TBTCH-c upon different conditions.
Fig. 3 The stacking mode (a) and intermolecular interactions (b-d) in
the crystals of TBTCH-g.
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and enhance the emissions. Moreover, the reverse and dislocated
stacking arrangements are advantageous to avoid the formation of
strong π–π stacking and thus lead to strong solid-state emission.
More importantly, the crystalline structures of the polymorphs with
weak non-covalent interactions are easily destroyed upon grinding,
which results in the changes of morphology and thus generating
MFC phenomena. It should be noted that although the ground
samples of TBTCH-g and TBTCH-c are both amorphous states, they
emit fluorescence with different colors and different quantum
efficiencies. This result suggests that the red-shifted emissions of
the polymorphs upon grinding should depend on the change of
stacking mode caused by the destruction of crystalline structures
rather than the planarization of the molecular conformation
because the latter will result in consistent ground samples.
Furthermore, the maximum absorption wavelengths of TBTCH-g
and TBTCH-c before and after grinding remain unchanged (Fig. S9,
ESI†), namely the effective conjugation is undisturbed, confirming
the formation of the excimers.17 This further confirms that the
change of stacking mode should play a more important role
compared with that of molecular conformation because the latter
will lead to the outstanding changes of the absorption
wavelengths.18 The possible reasons for the bathochromic
phenomenon in the MFC activities can be further explained as
follows: upon grinding, the crystal structure is destroyed and the
distances between molecules become smaller, which makes the
overlap between benzene rings larger, resulting the formation of
the excimers and thus the red-shifted emissions. Additionally, the
fact that the ground samples of these two compounds could not
restore to the corresponding original samples upon fuming or
annealing should be attributed that these large amounts of non-
covalent interactions caused by flexible chains and aromatic groups
are difficult to recover completely.6b
Notes and references
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DOI: 10.1039/D0CC05538G
1
(a) Z. Chi, X. Zhang, B. Xu, X. Zhou, C. Ma, Y. Zhang, S. Liu and
J. Xu, Chem. Soc. Rev., 2012, 41, 3878−3896; (b) Y. Lin, T. B.
Kouznetsova and S. L. Craig, J. Am. Chem. Soc., 2020, 142
,
99−103; (c) L. Huang, L. Liu, X. Li, H. Hu, M. Chen, Q. Yang, Z.
Ma and X. Jia, Angew. Chem. Int. Ed., 2019, 58
,
16445−16450.
2
3
4
Y. Sagara, S. Yamane, M. Mitani, C. Weder and T. Kato, Adv.
Mater., 2016, 28, 1073–1095.
S. A. Sharber, A. Mann, K. C. Shih, W. J. Mullin, M. P. Nieh
and S. W. Thomas III, J. Mater. Chem. C, 2019, 7, 8316−8324.
(a) Y. Dong, J. W. Y. Lam and B. Z. Tang, J. Phys. Chem. Lett.,
2015, , 3429–3436; (b) Z. Yang, Z. Chi, Z. Mao, Y. Zhang, S.
Liu, J. Zhao, M. P. Aldred and Z. Chi, Mater. Chem. Front.,
2018, , 861–890.
(a) S. Xue, X. Qiu, Q. Sun and W. Yang, J. Mater. Chem. C,
2016, , 1568–1578; (b) X. Huang, L. Qian, Y. Zhou, M. Liu, Y.
Cheng and H. Wu, J. Mater. Chem. C, 2018, , 5075–5096.
6
2
5
6
4
6
(a) Y. Sagara, T. Mutai, I. Yoshikawa and K. Araki, J. Am.
Chem. Soc., 2007, 129, 1520–1521; (b) M. Sase, S.
Yamaguchi, Y. Sagara, I. Yoshikawa, T. Mutai and K. Araki, J.
Mater. Chem., 2011, 21, 8347–8354; (c) V. K. Praveen, B.
Vedhanarayanan, A. Mal, R. K. Mishra and A. Ajayaghosh,
Acc. Chem. Res., 2020, 53, 496−507; (d) M. Teng, X. Jia, X.
Chen, Z. Ma and Y. Wei, Chem. Commun., 2011, 47
6078−6080; (e) C. Peebles, C. D. Wight and B. L. Iverson, J.
Mater. Chem. C, 2015, , 12156–12163.
(a) Y. Zhou, T. Li, Z. Zhou, F. Li, W. Huang, C. Huang and T. Yi,
Chem. Mater., 2006, 18, 2974−2981; (b) P. McNeice, Y. Zhao,
J. Wang, G. F. Donnelly and P. C. Marr, Green Chem., 2017,
19, 4690−4697.
,
3
7
8
9
J. R. Lakowicz, Principles of fluorescence spectroscopy. New
York: Plenum Press; 1983. p. 190.
M. P. Aldred, G. F. Zhang, C. Li, G. Chen, T. Chen and M. Q.
Zhu, J. Mater. Chem. C, 2013, 1, 6709–6718.
10 Z. Zhao, S. Gao, X. Zheng, P. Zhang, W. Wu, R. T. K. Kwok, Y.
Xiong, N. L. C. Leung, Y. Chen, X. Gao, J. W. Y. Lam and B. Z.
Tang, Adv. Funct. Mater., 2018, 28, 1705609.
In conclusion, a star-shaped TBTCH with twisted conformation
was designed and synthesized, in which the peripheral TPA units
and the central benzene are connected with multiple hydrazide
groups. TBTCH showed amazing multifunctional optical properties.
The solvatochromic property was due to the ICT effect and the AIE
property depends on the restriction of intramolecular rotation. This
compound also exhibited excellent gelation ability in chloroform
with good thermo-reversibility. Especially, TBTCH showed
polymorphic property even if the presence of multiple flexible
hydrazide groups. The difference emissions of TBTCH-g and TBTCH-
11 H. Auweter, H. Haberkorn, W. Heckmann, D. Horn, E.
Lüddecke, J. Rieger and H. Weiss, Angew. Chem., Int. Ed.,
1999, 38, 2188–2191.
12 J. Luo, Z. Xie, J. W. Y. Lam, L. Cheng, H. Chen, C. Qiu, H. S.
Kwok, X. Zhan, Y. Liu, D. Zhu and B. Z. Tang, Chem. Commun.,
2001, 1740–1741.
13 C. Jian, N. Tao, L. Xu, M. Liu, X. Huang, W. Gao and H. Wu,
ACS Sustainable Chem. Eng., 2019, 7, 11062–11068.
14 W. Gao, Y. Liang, X. Peng, Y. Hu, L. Zhang, H. Wu and B. He,
Biomaterials, 2016, 105, 1–11.
15 (a) M. L. Ma, Y. Kuang, Y. Gao, Y. Zhang, P. Gao and B. Xu, J.
Am. Chem. Soc., 2010, 132, 2719−2728; (b) Z. Shen, Y. Jiang,
T. Wang and M. Liu, J. Am. Chem. Soc., 2015, 137, 16109–
16115.
c
were confirmed to be ascribed to different molecular
conformations and non-covalent interactions. Furthermore, these
two polymorphs displayed high contrast red-shifted MFC activities
due to a crystalline-to-amorphous transition upon grinding. This
work demonstrates the applicability of a rational strategy to design
the multifunctional fluorescent material with polymorphic and MFC
activities, even if it contains multiple flexible chains.
16 C. Wang and Z. Li, Mater. Chem. Front., 2017,
17 E. Ramachandran and R. Dhamodharan, J. Mater. Chem. C,
2017, , 10469–10476.
1, 2174–2194.
5
18 X. Zhang, Z. Chi, X. Zhou, S. Liu, Y. Zhang and J. Xu, J. Phys.
Chem. C, 2012, 116, 23629–23638.
This work is supported by the National Natural Science
Foundation of China (Nos 21672164 and 21572165) and the
Zhejiang Provincial Natural Science Foundation of China (Nos
LY20B040004 and LY20B020014).
Conflicts of interest
There are no conflicts to declare
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ChemComm
Multifunctional properties of a star-shaped triphenylamine-be
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1,3,5-tricarbohydrazide fluorescent molecule containing multiple
flexible chains
Xin Feng, Yating Chen, Yunxiang Lei, Yunbing Zhou, Wenxia Gao, Miaochang Liu, Xiaobo
Huang and Huayue Wu
A star-shaped triphenylamine-benzene-1,3,5-tricarbohydrazide molecule containing multiple
flexible hydrazide chains displays amazing multifunctional optical properties including
solvatochromism, gelation, aggregation-induced emission, polymorphism, and mechanochromism.