Topology-Controlled AIEE of Iminocoumarin Luminophores

Article abstract of DOI:10.1002/asia.202100590

Aggregation-induced emission enhancement (AIEE) is an unusual phenomenon where luminophores show a higher photoluminescence efficiency in the aggregated and solid state. We report the design and synthesis of a series of luminophores 1–4 with imine functionality at 6 position of coumarin and studied their AIE propensities on self-assembly. The effect of the topology of the phenolic hydroxyl group on the emission behaviour of the luminophores has been investigated. The imines show significant solvatochromism with high emission in non-polar solvents, whereas the emission gets quenched in the polar solvent. The fluorescence in the toluene-hexane mixture arises due to the aggregation of fluorophores and falls under the category of AIEE. Not only the solution state emission of the isomeric iminocoumarin luminophores is notably varied, but also their solid-state emission found to be significantly different from each other. Moreover, the iminocoumarin 1 selectively recognizes Fe(III) over Fe(II) with a prominent color change. In situ oxidation of Fe(II) with H₂O₂ exhibits the same effect like Fe(III) and developed a chemical combinational logic gate.

Full text of DOI:10.1002/asia.202100590

CHEMISTRY
AN ASIAN JOURNAL
www.chemasianj.org
Accepted Article
Title: Topology-Controlled AIEE of Iminocoumarin Luminophores
Authors: Debasish Haldar, Deepta Chattapadhyay, Sahabaj Mondal,
and Santosh Kumar
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Asian J. 10.1002/asia.202100590
Link to VoR: https://doi.org/10.1002/asia.202100590
A Journal of
A sister journal of Angewandte Chemie
and Chemistry – A European Journal

10.1002/asia.202100590
Chemistry - An Asian Journal
FULL PAPER
Topology-Controlled AIEE of Iminocoumarin Luminophores
Deepta Chattapadhyay,[a]¶ Sahabaj Mondal,[a]¶ Santosh Kumar,[a] and Debasish Haldar*[a]
Dedication ((optional))
[a]
Deepta Chattapadhyay , Sahabaj Mondal, Santosh Kumar and Dr. Debasish Haldar
Department of Chemical Sciences and centre for Advance Functional Materials and Centre for Climate and Environmental Studies,
Indian Institute of Science Education and Research Kolkata
Mohanpur 741246, West Bengal, India
E-mail: deba_h76@iiserkol.ac.in; deba_h76@yahoo.com
¶ contributed equally to this work
Supporting information for this article is given via a link at the end of the document.
Abstract: Aggregation-induced emission enhancement (AIEE) is an
unusual phenomenon where luminophores show higher
photoluminescence efficiency in the aggregated and solid-state. We
report the design and synthesis of a series of luminophores 1-4 with
imine functionality at 6 position of coumarin and studied their AIE
propensities on self-assembly. The effect of the topology of the
phenolic hydroxyl group on the emission behaviour of the
luminophores has been investigated. The imines show significant
solvatochromism with high emission in non-polar solvents, whereas
the emission gets quenched in the polar solvent. The fluorescence in
the toluene-hexane mixture arises due to the aggregation of
fluorophores and falls under the category of AIEE. Not only the
solution state emission of the isomeric iminocoumarin luminophores
is notably varied, but also their solid-state emission found to be
significantly different from each other. Moreover, the iminocoumarin
1 selectively recognizes Fe(III) over Fe(II) with a prominent color
change. In situ oxidation of Fe(II) with H2O2 exhibits the same effect
like Fe(III) and developed a chemical combinational logic gate.
and claimed that aggregation-induced emission depends first
and foremost on the control over non-radiative decay and
applied the restriction of the intramolecular rotation to control the
non-radiative decay.[28]
Hence, the structure-property
relationships may shed some light on aggregation-induced
emission from luminogenic solid.[29–33] It would be also
interesting to design new molecules and control their
aggregation-induced emission.
In this context, we have designed and synthesized a series
of luminophores 1-4 with imine functionality at the 6 position of
coumarin and investigated their AIE propensities. Coumarin
generally emits in the blue-green region and has been used as
dye for lasers and sensors.[34-36] Ting and co-workers have
exploited the coumarin ligation technique for imaging protein-
protein interactions inside a living cell.[37] Recently there have
been several reports on solid-state optical properties of
coumarin-based fluorophores.[38-41] So far, few coumarin-based
compounds have been known to exhibit fluorescence in solid-
state. However, iminocoumarins are one of the less explored
classes of coumarins for their solid-state luminescence.[42-44] For
iminocoumarin luminophores 1-4, we have studied the effect of
the topology of the phenolic hydroxyl group on their emission
behavior. The luminophores show significant solvatochromism
with high fluorescence in non-polar solvents, but the
fluorescence quenched in a polar solvent. The emission of the
iminocoumarin luminophores in toluene-hexane mixture appear
due to aggregation. The solution state fluorescence of the
isomeric iminocoumarin luminophores is varied notably. In
addition, their solid-state emission also differs significantly.
Furthermore, the luminophore 1 recognizes Fe(III) selectively
over Fe(II) with a distinct change of color. However, on oxidation
of Fe(II) with H2O2 shows the same effect like Fe(III) and
developed a chemical logic gate.
Introduction
Fluorescent dyes with efficient emissions in the aggregate have
attracted considerable attention over the past two decades.[1-3]
Many such materials have found their increasing application in
the field of optoelectronics, such as light-emitting diodes[4,5]
,
optical data storage[6], as well as sensing, analytical chemistry,[7-
9], and life sciences.[10-13] The optical and electronic properties of
such materials in the devices are determined by the constituent
molecules' chemical structure and also largely dependent on
their aggregation propensities. Many fluorescent organic
molecules that show high emission in solution are not efficient
emitters in the solid-state. This happens because of increased
overlap between -orbitals of neighboring molecules in closely
packed head-to-head arrangements that facilitate delocalization
of excitons and increase charge carrier mobility.[14,15] Such
phenomena open up certain new pathways for non-radiative
decay, leading to a drop of solid-state luminescence, which is
commonly referred to as concentration quenching.[16,17] Even
though the photophysical properties in dilute solutions had been
studied extensively over several decades,[18-22] the emission
properties in aggregate state are gaining interest more
recently.[23-25] Tang and coworkers have reported the solid-state
emission of pentaphenylsilole[26] and tetraphenylethene (TPE),[27]
Results and Discussion
All the luminophores (Figure 1) were synthesized following
standard solution phase methodologies, purified, and
characterized by 1H NMR, 13C NMR, and Mass spectrometry
analysis. All the imine compounds were synthesized using
aminocoumarin compound
benzaldehyde, o-hydroxy
5
as
a
precursor.[41] The
p-hydroxy
benzaldehyde,
benzaldehyde, and m-hydroxy benzaldehyde were commercially
available. The design principle behind this was to analyze the
1
This article is protected by copyright. All rights reserved.

10.1002/asia.202100590
Chemistry - An Asian Journal
FULL PAPER
effect of additional phenyl rings on the optical properties
compared to the precursor coumarin molecule and substituent
topology on the optical properties of isomeric luminophores.
Figure 1. The schematic representation for the synthesis of iminocoumarin
luminophores 1-4. Reagents and conditions: 3 drops AcOH, EtOH, reflux, 8h,
80-90% yields.
Figure 2. (a) Emission spectra of iminocoumarin luminophore 1 in different
solvents, (b) Fluorescence quenching with MeOH addition. [Conc. 10-4 M] (c)
Emission spectra of iminocoumarin luminophore 2 in different solvents, (d)
Emission spectra of iminocoumarin luminophore 3 in various solvents. [Conc.:
10-4 M].
Firstly, we recorded the UV-Vis absorption spectra of
iminocoumarin luminophore 1 in THF solution to see whether
there is a difference from reported coumarin peak positions (275
and 335 nm due to * transition). It was observed that the
compound exhibits two peaks at 288 nm and 347 nm, and the
intensity of the band increases with an increase in concentration
(Supporting Information Figure S1).
To probe aggregation-induced emission behavior in solution, the
compound of interest is generally first dissolved in an organic
solvent like THF or acetonitrile to make a dilute solution and
emission spectra is recorded. Then a non-solvent-like water is
added to that solution. Since the -conjugated molecules are
most likely to be hydrophobic; under the mixture with high water
content, they cluster together to form aggregates, reflected in
higher emission in the mixture relative to the pure solution.
However, the challenge in our case is that iminocoumarin
luminophores are prone to hydrolysis in an aqueous mixture.
Therefore, we designed an alternate method to do the
experiment. Since iminocoumarin luminophores 2 and 3 are
insoluble in hexane, we used hexane as a non-solvent for these
molecules. The emission spectra were first recorded in toluene
(Conc. 4 X 10-5 M). Then emission in different toluene-hexane
fractions was measured, keeping the compound concentration
fixed. A gradual increase in the emission intensity was recorded
for both the compounds with an increase in hexane fraction in
the mixture (Figure 3a, c), which indicates AIEE for these
compounds.
To probe the aggregation phenomenon of iminocoumarin
luminophores 2 and 3, we have performed DLS studies. In 100%
toluene, the luminophore 2 has particles with an average
diameter of 14 nm. However, in 80% toluene and 20% hexane,
the average diameter of the aggregation increases to 20 nm
(Figure 3b). With % increase of hexane, the size of the
luminophore 2 aggregation keeps increasing, and at 20%
toluene and 80% hexane, the average diameter of the aggregate
is 470 nm (Figure 3b). The same phenomenon was observed for
iminocoumarin luminophore 3. In pure toluene, the luminophore
3 exhibits particles having a diameter of ca. 24 nm (Figure 3d).
With the increasing % of hexane in toluene, the size of the
luminophore 3 aggregates is increasing, and at 20% toluene and
80% hexane, the average diameter of the aggregate is 500 nm
(Figure 3d).
Interestingly, the iminocoumarin
1 shows solvatochromism
property with high emission in non-polar solvents and reduced
emission intensity in more polar solvents. The emission peak of
iminocoumarin luminophore 1 appears at 548 nm in non-polar
solvent cyclohexane. (Figure 2a) To further validate the
phenomena, we added polar solvent MeOH in cyclohexane
solution. We observed a significant decrease in emission
intensity when a small amount of MeOH was added. (Figure 2b).
Similar phenomena were observed for the iminocoumarin
luminophore 2 and 3, where the –OH group is present in meta
and para position, respectively, concerning the imine
functionality. Both the compounds were insoluble in hexane or
cyclohexane; therefore, we varied the solvents with increasing
polarity starting from toluene to acetonitrile. In toluene,
iminocoumarin luminophore 2 exhibits an emission peak at 526
nm, whereas the emission spectrum gets significantly red-shifted
in slightly more polar solvent ether. (Figure 2c)
The emission gets quenched in solvents with higher polarity.
The emission intensity decreases considerably with the addition
of 20 L of THF, which is more prominent when 20 L of
methanol is added instead of THF (Supporting Information
Figure S2). In iminocoumarin luminophore 3, where the hydroxyl
group is in the para position, the emission spectra follow the
same trend as 1 and 2, with emission intensity decreasing with
an increase in solvent polarity. Emission peak arises at 536 nm
in toluene (Figure 2d). Quenching of emission on the addition of
polar protic solvent is also observed here (Supporting
Information Figure S3). Analyzing these results shows that in
non-polar solvents, aggregate formation occurs due to relatively
less solubility of the compounds. The emission might be due to
those aggregate formations, a phenomenon commonly known
as aggregation induced emission enhancement (AIEE).
2
This article is protected by copyright. All rights reserved.

10.1002/asia.202100590
Chemistry - An Asian Journal
FULL PAPER
Information Figure S6). It emits in the yellow region with an
emission peak at 574 nm (Figure 4a). The iminocoumarin
luminophore 3 with a phenolic hydroxyl group at para position
gives the second most intense emission profile in the class, and
the emission is slightly red-shifted (Figure 4a). The emission
peak appears at 630 nm, although a shoulder peak is observed
in the green region. To ascertain the existence of multiple
emission bands, we have measured the emission lifetime
(Supporting Information Figure S7). The compound 2 has shown
a single excited state having a lifetime of 9.95 ns, whereas
compound 3 has shown two excited states having lifetime 4.6
and 1.8 ns, respectively. Iminocoumarin luminophore 2, in which
phenolic hydroxyl group is at meta position, also significantly
differs from solution state emission. Compared to the solution-
state peak at 526 nm, the solid-state emission peak appears at
626 nm, although the intensity is comparatively less (Figure 4a).
However, iminocoumarin luminophore 4, with an absence of the
phenolic hydroxyl substituent, shows a blue-shifted emission
profile; the emission peak is 557 nm (Figure 4a). Thus the
iminocoumarin luminophores show a significant difference in
intensity and peak position in their solid-state emission, which is
quite different from their solution state behavior.
Figure 3. (a) Emission spectra are showing aggregation-induced emission
enhancement (AIEE) of iminocoumarin luminophore
2 (b) DLS studies
Figure 4b depicts the emission of the solid powder of
iminocoumarin luminophores 1-4 and aminocoumarin 5 under
366 nm light. Hence, the colours of the emissions from the
aggregates of luminophores can be tuned from green to yellow
to brown and finally to orange by simply changing the position of
the hydroxyl group on the phenyl rings (Figure 4b). An apparent
trend has been observed in these isomeric AIEE that the
emission colour is red-shifted with increasing electron-donating
power of the substituent on the phenyl ring.
showing the enhancement of the aggregate size of iminocoumarin
luminophore 2 with the amount of hexane in toluene. (c) Emission spectra
show aggregation-induced emission enhancement (AIEE) of iminocoumarin
luminophore 3 (d) DLS studies showing the enhancement of the aggregate
size of iminocoumarin luminophore 3 with the amount of hexane in toluene.
(Excitation: 366 nm)
The aggregation phenomenon of iminocoumarin luminophores 2
and 3 was also studied by polar optical microscopy (POM). The
sample prepared with iminocoumarin luminophores 2 in 100%
toluene exhibits disperse tiny aggregates under POM
(Supporting Information Figure S4). However, the sample
prepared from iminocoumarin luminophores 2 in 20% toluene
and 80% hexane shows significantly bigger aggregates under
POM (Supporting Information Figure S4). Similar results were
obtained by sample prepared from iminocoumarin luminophores
3 in 100% toluene or 20% toluene and 80% hexane (Supporting
Information Figure S5).
We have also studied the solid-state photoluminescence of the
iminocoumarin luminophores 1-4. We also measured solid-state
luminescence of precursor aminocoumarin 5 for comparison.
Photoluminescence for all the compounds was measured for
powdered sample in HORIBA Fluoromax spectrofluorimeter.
Under 366 nm excitation wavelength (Figure 4a). It was
observed that the aminocoumarin 5 gives significantly red-
shifted solid-state emission with emission peaks arising at 601
nm (Figure 4a). Although not much difference was observed in
the spectral peak position in solution state emission for the
iminocoumarin luminophores 1-4, their solid-state emission
varied much from one compound to another. In addition, the
emission spectra in powder appear to feature more than one
emission band (550 nm for compound 3), with the band at 600-
650 nm being the most red-shifted one, though this effect does
not show up in solution. It is possible that in the solid state there
is a J-aggregation that leads to a new emission band. The
iminocoumarin luminophore 1 with a phenolic hydroxyl group at
ortho position showed the strongest emission amongst all with 5-
fold emission intensity as compound 5. This is due to the stable
six membered intramolecular hydrogen bond (Supporting
Figure 4. (a) Solid-state emission spectra of the iminocoumarin luminophore
1-4 and aminocoumarin 5, (b) The powdered samples of iminocoumarin
luminophore 1-4 and aminocoumarin 5 under 366 nm U.V. light.
Moreover, iminocoumarin luminophore
1
can selectively
recognize Fe(III) over Fe(II), and the colour of the solution
changes from yellow to brown (Figure 5a and Supporting
Information Figure S8). This is due to the formation of a soluble
3
This article is protected by copyright. All rights reserved.

10.1002/asia.202100590
Chemistry - An Asian Journal
FULL PAPER
Fe(III) complex (Figure 5d). To obtain information on the
association constant, we have also done the titration of Fe(III)
with compound 1 (Supporting Information Figure S9) and a Job
Plot (Supporting Information Figure S10) and Stern Volmer plot
(Supporting Information Figure S11). The stoichiometry is 2:1
for compound 1 : Fe(III). The value of the association constant is
0.17 x 104 M-1.Utilizing this fact that iminocoumarin 1 can
selectively recognize Fe(III) over other ions (Supporting
Information Figure S12), we have developed a combinational
logic gate system based on three inputs such as Fe(III), Fe(II),
and an in situ oxidizing agent H2O2, and one output (Figure 5b).
In the combinational logic gate, the presence and absence of
Fe(II), H2O2, and Fe(III) were designated as inputs 1 and 0
(Figure 5c). No change in color was assigned as 0 and 1 if color
changed to brown in the output. The input signals other than 000,
010 and 001, show colour change to brown (output 1) and thus
mimic the AND logic gate. Furthermore, the AND gate output
with Fe(III) develops the OR logic gate. We have also tried other
available oxidizing agents such as NaNO2 and m-
chloroperbenzoic acid. We have obtained same results but the
rate ware quite slow.
conjugated organic molecules and the possibility to design new
functional materials.
Experimental Section
Synthesis
The aminocoumarin 5 was synthesized following the reported
procedure.[41] The compound 5 was taken in a 100 mL flask and
dissolved in 30 mL absolute ethanol. Aromatic aldehyde was
added, followed by 2-3 drops of acetic acid. The mixture was
stirred under reflux for 8h with a CaCl2 guard tube. Then the
reaction mixture was cooled to room temperature, and a yellow
precipitate was observed. The solid precipitate was filtered and
washed with ether, and dried under vacuum to obtain pure
iminocoumarins. The reaction intermediates and final
luminophores were fully characterized by 1H NMR (400 MHz and
500 MHz) spectroscopy, 13C NMR (100 MHz and 125 MHz)
spectroscopy, and mass spectrometry.
NMR Experiments
All NMR spectroscopy was done on a 400 MHz Jeol or 500 MHz
Bruker spectrometer. Compound concentrations were in the 1–
10 mM range in CDCl3 or DMSO-d6 solutions.
Mass Spectrometry
Mass spectrometry was carried out on a Waters Corporation Q-
Tof Micro YA263 high-resolution mass spectrometer by
electrospray ionization (positive-mode).
Absorption spectroscopy
The absorption spectra of the luminophores were measured on
a Perkin Elmer UV/Vis spectrometer (Lambda 35) using a quartz
cell with a 1 cm path length.
Fluorescence spectroscopy
All fluorescence spectra were recorded on a Perkin Elmer
fluorescence spectrometer (L.S. 55) using a 1 cm path length
quartz cell. Slit widths of 2.5 nm / 2.5 nm were used.
Solid-state luminescence
Photoluminescence for all the compounds was measured for
powdered samples in HORIBA Fluoromax spectrofluorimeter
under 366 nm excitation wavelength.
Figure 5. (a) Fe(III) sensing by the iminocoumarin luminophore 1. (b)
Schematic of the logic gate. (c) Combinational logic gate system based on
three inputs, (d) Proposed Fe(III) complex with iminocoumarin luminophore 1.
Dynamic light scattering
Particle sizes were measured by dynamic light scattering (DLS),
Malvern Zetasizer Nano ZS (Malvern Instruments Ltd., UK)
equipped with a He-Ne laser (wavelength: 633 nm). First, we
made 10-2 (M) stock solution in toluene. Then we made 10-4 (M)
solution in the respective mix solvent (toluene/hexane). For DLS
size measurement, we took 20 µL of the respective mixture in
1mL solvent with a respective toluene/hexane ratio.
Optical Microscopy
Optical microscopy was performed to examine the aggregation
of the compounds from the solution. A drop of compound
solution was cast on a clean microscopic glass slide and dried
under a vacuum. The images were captured in an Olympus
polar optical microscope.
Conclusion
In conclusion, this work demonstrates the enhancement of the
emission of iminocoumarin luminophores due to the aggregation
in solution and solid-state. In particular, we report the effect of
the position of the phenolic hydroxyl group on the emission
behavior of the isomeric luminophores. The imines show
significant solvatochromism with high emission in non-polar
solvents, whereas the emission gets quenched in polar solvents.
The fluorescence in the toluene-hexane mixture arises due to
the aggregation of the fluorophores and falls under the category
of AIEE. Not only the solution state fluorescence of the
iminocoumarin luminophores is significantly varied, but also their
solid-state emission found to be notably different from each
other. Moreover, the iminocoumarin 1 selectively recognizes
Fe(III) over Fe(II) with yellow to brown colour change. In situ
oxidation of Fe(II) with H2O2 exhibits the same effect like Fe(III)
and developed a chemical combinatorial logic gate. This study
opens a new direction of topology-controlled AIEE properties of
Supporting Information
Supporting information contains a detailed description of the
experimental section, including synthesis and characterization.
4
This article is protected by copyright. All rights reserved.

10.1002/asia.202100590
Chemistry - An Asian Journal
FULL PAPER
[32] Y. Dong, J. W. Y. Lam, A. Qin, J. Liu, Z. Li, B. Z. Tang, J. Sun, H. S. Kwok,
Appl. Phys. Lett. 2007, 91, 011111.
Acknowledgments
[33] M. Freemantle, Chem. Eng. News 2001, 79, 29-32.
[34] B.D. Wagner, Molecules 2009, 14, 210-237.
This work is supported by IISER-Kolkata, India. D. C.
acknowledges DST for Inspire fellowship. S. M. and S. K. are
thankful to CSIR, India, for the research fellowship.
[35] K. Hara, Z. S. Wang, T. Sato, A. Furube, R. Katoh, H. Sugihara, Y. Danoh,
C. Kasada, A. Shinpo, S. Suga, J. Phys. Chem. B 2005, 109, 15476–
15482.
[36] R. J. Nedumpara, K. J. Thomas, V. K. Jayasree, C. P. Girijavallabhan, V.
P. N. Nampoori, P. Radhakrishnan, Appl. Opt. 2007, 46, 1159–1168.
[37] S. A. Slavoff, D. S. Liu, J. D. Cohen, A. Y. Ting, J. Am. Chem. Soc. 2011,
133, 19769–19776.
Keywords: aggregation-induced emission • iminocoumarin •
luminophores • solid-state • logic gate
[1] S. Suzuki, S. Sasaki, A. S. Sairi, R. Iwai, B. Z. Tang, G. Knoishi, Angew.
Chem., Int. Ed. 2020, 59, 9856 – 9867.
[38] Y.F. Sun, S.H. Xu, R.T. Wu, Z.Y. Wang, Z.B. Zheng, J.K. Li, Y.P. Cui,
Dyes and Pigments 2010, 87, 109-118.
[2] X. Wang, O.S. Wolfbeis, R.J. Meier, Chem. Soc. Rev. 2013, 42, 7834-7869.
[3] S. Varghese, S. Das, J. Phys. Chem. Lett. 2011, 2, 863-873.
[4] S.R. Forrest, Nature 2004, 428, 911–918.
[39] S.Y. Park, M. Ebihara, Y. Kubota, K. Funabiki, M. Matsui, Dyes and
Pigments 2009, 82, 258-267.
[40] K. Kubo, T. Matsumoto, K. Ideta, H. Takechi, H. Takahashi, Heterocycles
2012, 84, 315-321.
[5] Y. S. Zhao, H. Fu, A. Peng, Y. Ma, Q. Liao, J. Yao, Acc. Chem. Res. 2010,
43, 409-418.
[41] A. Pramanik, D. Haldar, RSC Adv. 2017, 7, 389.
[42] H. Turki, S. Abid, N. Saffon, S. Fery-Forgues, Dyes and Pigments 2012,
94, 81-87.
[6] B. H. Cumpston, S. P. Ananthavel, S. Barlow, D. L. Dyer, J. E. Ehrlich, L. L.
Erskine, A. A. Heikal, S. M. Kuebler, I.-Y. S. Lee, D. McCord-Maughon,
J. Qin, H. Röckel, M. Rumi, X.-L. Wu, S. R. Marder, J. W. Perry, Nature
1999, 398, 51–54.
[43] N. Abid, H. Turki-Guermazi, K. Khemakhem, S. Abid, N. Saffon, S. Fery-
Forgues, Dyes and Pigments 2014, 101, 164-171.
[7] R. Petermann, M. Tian, S. Tatsuura, M. Furuki, Dyes Pigm. 2003, 57, 43-
54.
[44] K. Khemakhem, M. Soulié, R. Brousses, H. Ammar, S. Abid, S. Fery-
Forgues, Chem. Eur. J. 2015, 21, 7927-7937.
[8] H Li, Cai L, Chen Z. in Coumarin-derived fluorescent chemosensors;
Advances in Chemical Sensors, (Eds.:W Wang), InTech, 2011, pp.
121-150. ISBN 978-953-307-792-5.
[9] S. Fery-Forgues, Nanoscale 2013, 5, 8428-8442.
[10] J. Mei, N. L. C. Leung, R. T. K. Kwok, J. W. Y. Lam, B. Z. Tang, Chem.
Rev. 2015, 115, 11718 – 11940.
[11] J. Mei, Y. Hong, J. W. Y. Lam, A. Qin, Y. Tang, B. Z. Tang, Adv. Mater.
2014, 26, 5429 – 5479.
[12] Y. Chen, J. W. Y. Lam, R. T. K. Kwok, B. Liu, B. Z. Tang, Mater. Horiz.
2019, 6, 428 – 433.
[13] Hong Yang, Mengqi Li, Chong Li, Qianfu Luo, Ming-Qiang Zhu, He Tian,
Wei-Hong Zhu, Angew. Chem., Int. Ed. 2020, 59, 8560– 8570.
[14] A. B. Koren, M. D. Curtis, A. H. Francis, J. W. Kampf, J. Am. Chem. Soc.,
2003, 125, 5040–5050.
[15] M. D. Curtis, J. Cao, J. W. Kampf, J. Am. Chem. Soc. 2004, 126, 4318–
4328.
[16] J. B. Birks, Photophysics of Aromatic Molecules, Wiley: London, 1970.
[17] Y. Hong, J. W. Y. Lama, B. Z. Tang, Chem. Commun. 2009, 4332–4353.
[18] S. W. Thomas III, G. D. Joly, T. M. Swager, Chem. Rev. 2007, 107, 1339-
1386.
[19] F. J. M. Hoeben, P. Jonkheijm, E. W. Meijer, A. P. H. J. Schenning, Chem.
Rev. 2005, 105, 1491-1546.
[20] U. H. F. Bunz, Chem. Rev., 2000, 100, 1605-1644.
[21] F. Hide, M. A. Diaz-Garcia, B. J. Schwartz, A. J. Heeger, Acc. Chem. Res.
1997, 30, 430-436.
[22] S. M. Borisov, O. S. Wolfbeis, Chem. Rev. 2008, 108, 423-461.
[23] J. Mei, N. L. C. Leung, R. T. K. Kwok, J. W. Y. Lam, B. Z. Tang, Chem.
Rev. 2015, 115, 11718-11940.
[24] J. Mei, Y. Hong, J. W. Y. Lam, A. Qin, Y. Tang, B. Z. Tang, Adv. Mater.
2014, 26, 5429-5479.
[25] Y. Hong, J. W. Y. Lam, B. Z. Tang, Chem. Soc. Rev. 2011, 40, 5361-5388.
[26] J. Luo, Z. Xie, J. W. Y. Lam, L. Cheng, H. Chen, C. Qiu, H. S. Kwok, X.
Zhan, Y. Liu, D. Zhuc, B. Z. Tang, Chem. Commun. 2001, 1740 – 1741.
[27] H. Tong, Y. Dong, M. Haubler, J. W. Y. Lam, H. H.-Y. Sung, I. D. Williams,
J. Sun and B. Z. Tang, Chem. Commun. 2006, 1133–1135.
[28] J. Chen, C. C. W. Law, J. W. Y. Lam, Y. Dong, S. M. F. Lo, I. D. Williams,
D. Zhu, B. Z. Tang, Chem. Mater. 2003, 15, 1535 – 1546.
[29] J. W. Chen, B. Xu, X. Y. Ouyang, B. Z. Tang, Y. Cao, J. Phys. Chem. A
2004, 108, 7522-7526.
[30] H. Tong, Y. Hong, Y. Dong, Y. Ren, M. Haeussler, J. W. Y. Lam, K. S.
Wong, B. Z. Tang, J. Phys. Chem. B 2007, 111, 2000.
[31] Q. Zeng, Z. Li, Y. Dong, C. Di, A. Qin, Y. Hong, L. Ji, Z. Zhu, C. K. W. Jim,
G. Yu, Q. Li, Z. Li, Y. Liu, J. Qin, B. Z. Tang, Chem. Commun. 2007,
70-72.
5
This article is protected by copyright. All rights reserved.

10.1002/asia.202100590
Chemistry - An Asian Journal
FULL PAPER
Entry for the Table of Contents
Text for Table of Contents. The isomeric iminocoumarin luminophores exhibit significantly different fluorescence in aggregate and
solid-state due to aggregation induced emission enhancement. The topology of the phenolic hydroxyl group has dictated the
emission behaviour of the isomeric luminophores. The selective detection of Fe(III) over Fe(II) by luminophore 1 helps to develop a
chemical combinatorial logic gate.
6
This article is protected by copyright. All rights reserved.