Synthesis and investigation of the photophysical, electrochemical and theoretical properties of phenazine-Amine based cyan blue-red fluorescent materials for organic electronics

Article abstract of DOI:10.1039/c9nj06109f

To understand the structure-property relationship, we have designed and synthesized seven novel donor-Acceptor based phenazine-Amines, 2-8, by the Buchwald-Hartwig coupling amination reaction in moderate yield. The synthesized molecules were fully characterized and the influence of modulating the donor and phenazine core on the optoelectrochemical properties was studied. The absorption spectra of 2-8 display intramolecular charge transfer (ICT) transitions in the range of 431-501 nm. Dyes 2-8 exhibit positive solvatofluorochromism and emit in the cyan blue-red region with emission maxima at 498-641 nm on excitation at their respective ICT maxima in toluene, chloroform, DCM and neat solid film. The photophysical studies of the dyes in different THF/water mixtures revealed aggregation induced emission (AIE) features in dyes 2, 3 and 5. The HOMO and LUMO energy levels were found to be in the ranges of-5.39 to-5.68 eV and-3.59 to-3.71 eV, respectively, with electrochemical band gaps within the range 1.73-2.04 eV. Theoretical studies of the molecules were also carried out by using TD-DFT calculations. The comparable electrochemical energy levels to ambipolar materials, solid state luminescence with AIE characteristics and good thermal stability of the synthesized dyes signify their potential to be used as solid state emitters and ambipolar materials in optoelectronics.

Full text of DOI:10.1039/c9nj06109f

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10.1039/C9NJ06109F
Synthesis and Investigation of Photophysical, ElectrochemicalDO
a
I:
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Theoretical properties of Phenazine-Amine based Cyan blue-Red
Fluorescent Materials for Organic Electronics
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a*
Deepali N. Kanekar , Dr. Sajeev Chacko and Prof. Rajesh M. Kamble
a
Department of Chemistry, University of Mumbai, Santacruz (E), Mumbai 400 098, India
Department of Physics, University of Mumbai, Santacruz (E), Mumbai 400 098, India
b
e-mail: kamblerm@chem.mu.ac.in
Abstract
To understand structure‒property relationship, we have designed and synthesized seven novel
donor‒acceptor based phenazine‒amines 2−8 by Buchwald‒Hartwig coupling amination
reaction in moderate yield. The synthesized molecules were fully characterized and studied for
influence of modulating donor and phenazine core on optoelectrochemical properties.
Absorption spectra of 2−8 display intramolecular charge transfer (ICT) transitions in the range
of 431−501 nm. Dyes 2−8 exhibit positive solvatofluorochromism and emit in cyan blue‒red
region with emission maxima 498–641 nm on excitation at their respective ICT maxima in
toluene, chloroform, DCM and neat solid film. The photophysical studies of dyes in different
THF/water mixture revealed aggregation induced emission (AIE) feature in dye 2, 3 and 5. The
HOMO and LUMO energy level were found in the range of ‒5.39 to ‒5.68 eV and ‒3.59 to
‒3.71 eV with electrochemical band gap within the range 1.73−2.04 eV. Theoretical studies of
molecules were also carried out by using TD‒DFT calculations. The comparable
electrochemical energy level to ambipolar materials, solid state luminescence with AIE
characteristic and good thermal stability of synthesized dyes signify their potential to be used
as solid state emitter and ambipolar materials in optoelectronics.
Keywords: Donor‒Acceptor (D−A), Phenazine‒amines, Intramolecular charge transfer (ICT)
transitions, Aggregation Induced Emission (AIE), HOMO and LUMO energy levels,
Ambipolar materials.

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DOI: 10.1039/C9NJ06109F
Introduction
Organic dyes have boomed the global market of optoelectronics with its wide peculiarities such
as easy synthesis and low cost processing techniques, broad scale of solubility in organic
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solvents, tuning of fluorescence with positive solvatochromism and mechanochromism,
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capability of aggregation induced emission (AIE) and thermally activated delay fluorescence
(
TADF) phenomenon,4 excellent semiconducting properties with small band gap,5
6
electroluminescence, etc. Due to such remarkable properties organic dyes have been
extensively explored in various organic electronics applications including organic light
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emitting diodes (OLEDs), organic field effect transistors (OFETs), dye sensitized solar cells
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(DSSCs), sensors, non-linear optics, organic storage media and so on. Although polymer
are major class, burgeoning donor‒acceptor (D‒A) aspect in small organic molecules
comprised with outstanding properties such as, unique molecular packing, structure‒property
relationship, tuneable optoelctronic properties and thermal stability.13 Past reports show
interesting optoelectronic properties of various D‒A based molecules in which electron rich
triarylamine/diarylamine embedded with
electron deficient core like carbazole,14
quinoxaline,15 anthracene,16 pyrazine17 and phenazine.18 In such D‒A type molecules
intramolecular charge transfer (ICT) electronic transition from donor to acceptor plays a key
role in tuning of luminescent properties. Thus, precise tuning of emission colours through
modulation of ICT character by appropriate selection of donor and acceptor moiety in molecule
allow us to obtain desired luminescence. However, a problem associated with emission of many
19
dyes in aggregation state is “aggregation-caused quenching” (ACQ). This weakening or
quenching in luminescence has observed for traditional luminophores with discotic shapes,
planar geometry which usually cause non‒radiative relaxation due to intermolecular π-π
stacking interactions of the molecules. Tang et al. in 2001 encountered this notorious ACQ
effect by introducing a family of molecules emissive in solid/aggregate state and has provided

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DOI: 10.1039/C9NJ06109F
new thought of “aggregation-induced emission” (AIE). This AIE feature of the molecule is
dependent on mode of molecular aggregation/conformation and effective electronic
conjugation.4,21 Besides this, attachment of AIE active groups to conventional ACQ
fluorophores could help to trigger the problem of ACQ.22 The incorporation of bulky
triarylamines with electron deficient acceptor core also can be an effective approach to obtain
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AIE active fluorophores due to their low tendency to aggregate. Triarylamines has greatly
utilized as a donor in D‒A based molecules due to its excellent hole transporting property and
ability to induce bright fluorescence.24
Charge transport property of small D‒A based molecules is result of redox processes
taking place within the molecule that found to influence by nature of embedded donor and
acceptor in framework. Organic dyes ensuring p-type charge transfer are widely developed
compared to n-type and ambipolar materials as latter show difficulty in synthesis due to their
instability under ambient conditions. As the n-type materials are indispensable part of
electronic circuit and ambipolar materials holds ability to transfer both holes as well as
electrons in single circuit thus can simplify and reduce the cost of device, there is a great
2
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demand for n-type and ambipolar materials in organic electronics. The p-type material has
HOMO level around −5.0 eV and n-type26 materials has LUMO energy level of around
2
7
−
4.0 eV whereas to commence ambipolar charge transfer in material, it’s HOMO energy level
should be below or equal to ‒5.0 eV and LUMO levels must be less than ‒3.15 eV. These
energy level values suggest that introduction of N or S-atom in structural core or electron
withdrawing groups such as ‒F, ‒CN, ‒Cl, ‒NO ‒COOH, ‒CF in p-type materials could be
2
,
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serve as a possible way to originate electron transport feature or ambipolar charge transport in
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the molecule. Hence, fusion of right donor and acceptor pair in framework accordingly
enables us to obtain preferred charge transport in dye.
By understanding importance of structure-property relationship in D−A based molecules,

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DOI: 10.1039/C9NJ06109F
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Figure 1. Molecular structure of compounds 2‒8.
herein we report synthesis and optoelectronic properties of novel phenazine‒amine derivatives

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2
−8 in which various electron donating diarylamines/heterocyclic/aliphatic amine fused with
DOI: 10.1039/C9NJ06109F
derived phenazine core. Phenazines alongwith optoelectronic properties has wide spectrum of
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biological properties such as antibacterial, antifungal, antimicrobial activity as well as its
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derivatives are useful as biopesticides in agriculture. The design of the molecules 2−8 mainly
based on the fact that resulted triarylamines are well known donors and derived phenazine core
can act as efficient electron acceptor due to presence of two ‘N-atoms’ in ring and attached
electron withdrawing benzoyl group to the core. In compound 8, we used morpholine as donor
to see the rigid effect of aliphatic cyclic amine. Further, studies explored the influence of
electron donating (‒OCH ) and withdrawing (‒NO ) group on triarylamine moiety on the
3
2
optoelectrochemical properties such as intramolecular charge transfer transition (ICT),
HOMO−LUMO energy levels and band gap has been studied. The structures of synthesized
molecules 2−8 are shown in Figure 1.
Results and discussion
Synthesis and Characterization
1
Compound 1 is prepared according to the reported procedure and confirmed by H NMR,
13C NMR and MALDI-TOF. Compounds 2−8 were obtained by Buchwald-Hartwig coupling31
of 1 with the corresponding diarylamine/heterocyclic amines in the presence of Pd (dba)
2
3
catalyst, SPhos ligand and t-BuONa as a strong base in toluene. The synthesized compounds
–8 were obtained in moderate 50%–81% yield as yellow‒dark red solids soluble in common
organic solvents including toluene, dichloromethane (DCM), chloroform, tetrahydrofuran
THF), dimethyl sulfoxide (DMSO). However, they are completely insoluble in water. The
2
(
1
13
identity and purity of all the target compounds were confirmed by FT−IR, H, C−NMR
spectroscopy, MALDI‒TOF mass spectrometry and elemental analysis. The synthetic route of
compound 2−8 is shown in Scheme 1.

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Scheme 1. Synthetic route of 2–8.
Photophysical Properties
Absorption and emission properties of compounds 1−8 were studied by UV‒Vis and
fluorescence spectroscopy. In order to understand effect of solvent polarity on photophysical
property, the absorption and fluorescence spectra were recorded in different polarity of solvents
(toluene, chloroform, dichloromethane, and dimethyl sulphoxide) and in neat solid film. The
UV‒Vis absorption spectra of compounds 2−8 in toluene and dichloromethane are presented
in Figure 2 while pertinent data summarized in Table 1.

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The
absorption
spectra
of
parent
(3,6-dibromodibenzo[a,c]phenazin-11-
DOI: 10.1039/C9NJ06109F
yl)(phenyl)methanone (1) and its derivatives 2−8 in varying polarity of solvents (See
supporting information (SI), Figure S1) exhibit major bands at 270−408 nm and 256−399 nm
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Figure 2. UV−Vis absorption spectra of compounds 2−8 in toluene (a) and dichloromethane
(
b).
*
*
respectively corresponds to high energy n‒π and π‒π transitions occurring in entire molecular
*
*
system. Apart from n‒π and π‒π transitions, substitution with different donor in synthesized
compounds show distinct lower energy intramolecular charge transfer transition around
4
31−501 nm. These weaker energy absorption band assigned to intramolecular charge transfer
(
ICT) from electron donating diarylamine, heterocyclic and aliphatic amines to electron
3
2
accepting phenazine core and has found sensitive to nature of donor moiety. Thus, ICT band
is considered as a characteristic feature of the D−A architecture. Absorption maxima of 1−8
holds high molar absorptivity and almost unaffected to varying solvent polarity demonstrate
more stability of ground state compared to excited state. Further, the presence of electron
donating ‒OCH group on diarylamine show bathochromic shift of 11−17 nm in ICT transition
3
in 4 while the presence of electron withdrawing ‒NO group on diarlyamine moiety was
2
hypsochromically shifts the ICT transition by 21−33 nm in 5.

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Moreover, heterocyclic amine like phenothiazine, carbazole and morpholine exihibit the
blue shift of 31−39 nm in 6, 46−51 nm in 7 and 29−32 nm in 8 in ICT transitions as compared
to diphenylamine derivatives. In all the solvents, dye 6 display red shifted ICT band than 7 due
to enhanced donating ability of 6 because of electron rich sulfur atom in phenothiazine ring as
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compared to carbazole. Further, the absorption spectra of 2−8 in neat solid film display
broadening of bands with slight red shift of 2−33 nm in absorption maxima assigned to the
molecular aggregation in molecules.
Table 1. Absorption data of 1‒8.
λabsa nm, ( log εmax M cm )
−1
−1
λabsa
Compd
Toluene
CHCl3
DCM
DMSO
Solid Film
2
85 (5.48),
293 (5.30),
384 (5.31),
408 (5.22)
274 (5.32)
385 (4.84),
406 (4.92)
270 (5.72),
387 (4.84),
407 (4.88)
2
71, 395,
417
387 (5.11),
08 (5.22)
81 (5.44),
1
2
4
2
280 (5.50),
399 (4.46),
481 (5.05)
256 (5.32),
332 (4.86),
484 (4.69)
2
85 (5.26),
84 (5.04)
305 (5.37)
483 (5.23)
290, 481
336, 504
4
3
02 (4.85),
283 (5.36),
327 (5.26),
483 (5.14)
257 (5.41),
327 (5.37),
479 (5.23)
256 (5.43),
327 (5.04),
483 (4.83)
3
4
326 (5.00),
4
80 (4.86)
281 (5.27),
334 (5.09),
283 (5.27),
339 (5.08),
498 (4.98)
273 (6.04),
411 (4.64),
495 (5.28)
256 (5.57),
501 (4.89)
3
35, 478,
09
5
4
94 (4.99)
2
3
83 (5.25),
08 (5.17),
2
74 (5.21),
306 (5.11),
53 (5.17)
268 (5.63),
358 (5.01),
450 (5.28)
257 (5.60),
361 (4.72),
451 (4.89)
360, 391,
457
5
6
445 (5.16),
462 (5.16)
4
2
82 (5.24),
381 (4.73),
44 (4.45)
287 (5.25),
399 (4.72),
457( 4.45)
287 (5.50),
380 (5.04),
450 (4.91)
258 (5.22),
382 (4.80),
453 (4.45)
360, 402,
4
67
4
2
83 (5.31),
290 (5.29),
318 (5.07),
433 (4.85)
262 (5.98),
277 (5.97),
431 (5.08)
257 (5.31)
439 (4.07),
3
60, 384,
64
7
8
320 (5.05),
437 (4.82)
4
2
98 (5.99),
372 (5.28),
52 (5.05)
298 (5.45),
380 (4.85),
452 (5.24)
262 (5.43),
380 (4.84),
452 (5.24)
258(5.94),
389 (4.34),
469 (4.84)
266, 392,
454
4
-6
a
Recorded in10 M solution

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DOI: 10.1039/C9NJ06109F
The other photophysical factors such as emission data, optical band gap, stokes shift and
quantum yield were calculated and summarized in Table 2. Generally, the emission of D−A
based dye with strong ICT character is often affected by solvent polarity. Hence, to confirm
ICT character of compounds 2−8, the solvent effect on emission were investigated. Dyes 2−8
emit in cyan blue‒red region with emission maxima 498–641 nm on excitation at their
respective ICT maxima in toluene, chloroform, DCM and neat solid film (Figure 3 and SI
Figure S2).
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Figure 3. Emission spectra of 2−8 in toluene (a), neat solid film (b).
Intriguingly, the emission spectra of 2−8 in different polarity solvent indicate occurrence
of positive solvatochromism. The cyan blue‒yellow fluorescence (λEmax: 498−588 nm) of dyes
2−8 in toluene were bathochromically shifted by 21‒58 nm and 33‒57 nm in chloroform and
DCM correspondingly drawn fluorescence to green‒orange region (SI, Figure S3).
Additionally, solvatochromism is responsible for decrease in emission intensity of dyes on
increasing polarity of solvents. Hence, 2−8 does not display any emission in highly polar
DMSO. This notable solvatochromism is assigned to enhanced dipole moments of
ICT‒fluorophores in polarized excited state that get stabilized by a high polar environment of
solvent which decreases the energy of excitation state and brings red shift in the emission.34

New Journal of Chemistry
Page 10 of 38
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
View Article Online
DOI: 10.1039/C9NJ06109F
The positive solvatochromism in 2, 3, 7 and 8 show good correlation between emission maxima
3
5
and ET(30) polarity parameter of solvents and presented in Figure 4.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 4. The positive solvatochromism of dyes 2, 3, 7 and 8, (a) dependence of emission
maxima of 2, 3, 7 and 8 on polarity parameters (ET(30)) of solvents, (b) dependence of emission
intensities of 2, 3, 7 and 8 on polarity parameters of solvents and (c) photographs of 2, 3, 7 and
-6
8
in solid powder state and in increasing polarity of solvents (10 M) under UV‒Visible light.
The emission spectra presented in Figure 3 (a), display a bathochromic shift of 50−56 nm
in compound 4 and hypsochromic shift of 25−31 nm in compound 5 compared to other
diphenylamine derivatives in toluene attributed to presence of electron donating ‒OCH and
3
electron withdrawing ‒NO group on triarlyamine moiety respectively. Further, fluorescence
2
quenching of 4 and 5 in polar media suggesting manifestation of non-radiative relaxation from
excited state to ground state by molecules due to presence of polar functional group such as
‒
OCH and ‒NO . On the other side, the effect of weak electron donor carbazole unit in dye 7
3 2
own hypsochromic shift of 32−41 nm that display cyan blue to yellow fluorescence in toluene,
chloroform and DCM compared to other derivatives (Figure 4). However, quenching of

Page 11 of 38
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DOI: 10.1039/C9NJ06109F
luminescence for dye 6 in all solvents probably as a consequence of charge separation by an
intramolecular photo-induced electron transfer (PET) from strong donor phenothiazine to
acceptor phenazine core. These probability of occurrence of PET in 6 were further confirmed
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
by density functional theory (DFT) and discussed in detail in theoretical section.36
The considerable stokes shift exhibited by dyes 2−8 in toluene dramatically increases on
increasing polarity of solvent and in neat solid film. These large stokes shift corresponds to
intramolecular charge transfer in excited state and suggest the change in the ground and excited
Table 2. Emission data, Stokes shift, Optical band gap and Quantum yield of 1−9.
a
-1
λ
nm,
Solid
Film
Stokes shift, cm ,
Solid
Film
emi ,
퐨퐩퐭
b
c
Compd
( 퐄퐠 ,퐞퐕)
(흓F)
Toluene CHCl3
DCM
Toluene CHCl3 DCM
1
2
3
4
5
6
−
−
−
−
−
−
−
−
3
2
4
4
754
737
045
429
538
1.91)
579
(1.76)
596
(1.72)
581
2116
(0.36)
3390
4008
(
(
(
(
(0.09) (0.04)
3492 3822
(0.09) (0.03)
5
32
1.88)
88
581
(1.77)
587
(1.68)
584
641
573
−
1445
(0.48)
5
−
−
−
−
−
−
3236
(0.16)
−
−
−
−
−
−
1.74)
507
2.00)
2709
(0.54)
−
−
−
5
601
58,
3630
4
98
543
(1.89)
555
(1.78)
2802
(0.39)
4678
(0.14) (0.07)
5200
7
8
(2.06)
5
134
5
31
552
(1.85)
b
564
(1.76)
592
3591
(0.31)
4007 4393
(0.26) (0.10)
(1.95)
a
-6
Recorded in 10 M solution, Optical band gap (in parentheses) estimated using emission and
ퟏퟐퟒퟎ.ퟖ
퐨퐩퐭
c
excitation spectra 퐄퐠
=
퐞퐕. Quantum yield (in parentheses) with reference to
(
)
훌퐨퐩퐭퐞퐝퐠퐞
fluorescein (휙 = 0.79 in 0.1 M NaOH).
state geometry. The large stokes shift of luminophores are desirable for its application in
optoelectronics as it ensures that there is no reabsorption of the emitted photons.

New Journal of Chemistry
Page 12 of 38
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
View Article Online
DOI: 10.1039/C9NJ06109F
Solvent dependable luminescence of ICT based dyes 2−8 responsible for decrease in band
gap on increase in polarity of solvent from toluene (2.06−1.74 eV) to chloroform and DCM
(1.89−1.68 eV). The quantum yield of 2−8 were calculated using fluorescein (Ф = 0.79 in
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
0
.1 N NaOH) as reference and are in the range 0.16‒0.54 in toluene (Table 2). Like decreasing
optical band gap, the prominent decrease in the quantum yield in more polar solvents were
observed for synthesized dyes which can be explained by energy gap law, that says, “internal
conversion efficiency of excited state and luminescence is reduced with decrease in energy gap
between ground and excited states.”
On the other hand, all the dyes except 6 show more or less emission in neat solid film.
The intermolecular aggregation followed by more complex charge separation and
37
recombination dynamics could be the reason of ACQ in phenothiazine containing dye 6. As
discussed, mode of molecular aggregation/conformation and effective electronic conjugation
plays a vital role in determining solid state emission/AIE. However, it’s found that the
molecules which exhibit solid state emission are mostly AIE active. Thus, to study AIE
phenomenon in detail, we chose molecules 2, 3, 5 and 7 which has bright emission in solid
state.
AIE Phenomenon
Premilinary to evaluate existance of AIE characteristic in selected dyes, we have prepared
series of THF/water mixtures (0‒100%) of dyes according to reported procedure to form
organic nanoparticles38 and observed under 365 nm UV illumination. Figure 5 show
fluorescent image of 2 and 3 dissolved in different THF/water mixtures (0‒100%) (for AIE of
5
and 7, see SI Figure S4). This show the quenching in emission of dyes after addition of
water was greatly recovered in dye 2, 3 and 5 at higher water fractions indicates presence of
AIE activity. Beside this, quenching of emission throughout THF/water mixture of dye 7 has
observed. This could be assigned to planar ring carbazole as a donor in dye 7, may experiencing

Page 13 of 38
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damage of C−H∙∙∙π bond on addition of water and responsible for more planar ge
D
o
O
m
I: 1
e
0
t
.1
r
0
y
39
a
/C9NJ06109F
n
d
π‒π stacking of molecules which makes it AIE inactive.39
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 5. Photograph of 2 (a) and 3 (b) in THF‒water mixture with subsequently increasing
-5
water fractions (10 M) by 10% under UV‒Visible light.
Furthermore, the emission of chosen molecules were recorded in different THF/water
fractions for the comparision of PL intensities. The photoluminscence (PL) spectra of 2 and 3
in different THF/water fractions presented in Figure 6. The intense emission in pure THF
attributed to intramolecular charge transfer from the donor diarylamine/heterocyclic amines to
acceptor phenazine core. Further, the gradual addition of water to THF increases polarity of
solution and quenches the emission upto 50% ƒ . Such quenching of emission on addition of
w
water could be due to two factors (i) insolubility of luminophores in water and (ii) occurrence

New Journal of Chemistry
Page 14 of 38
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2
3
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5
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1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
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DOI: 10.1039/C9NJ06109F
of twisted intramolecular charge transfer (TICT) state in polar environment which often leads
4
0
to non-radiative quenching process usually termed as “dark state”. The improved PL intensity
at higher water percentage from 70 to 80% ƒ in 2 and 60 to 80% ƒ in 3 and 5 indicate
w
w
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
formation of nanoparticle suspension/nanoaggregates and validate presence of AIE activity in
dyes 2, 3 and 5.
-5
Figure 6. Fluorescence spectra of 2 (a) and 3 (b) (10 M) in THF−water mixture with
increasing water fractions (ƒ ) and 2 (A) and 3 (B) plots of PL intensity (I/I ) versus ƒ .
w
0
w
On aggregation, the local environment become less polar and D−A structure become less
twisted. This restricts intramolecular rotation (RIR) tend to inhibit dark TICT process and
blocks non-radiative channel which enables the molecules to emit strongly in aggregate state.41
Luminophores 2, 3 and 5 exhibit orange fluorescence in aggregate state where the more and
less emission intensity of aggregated suspension is assigned to different physical constraint of

Page 15 of 38
New Journal of Chemistry
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DOI: 10.1039/C9NJ06109F
molecule in aggregate state and more or less number of nanoparticles yields in different
THF/water mixture. However, it is hard to control the formation of nanoparticle at high water
4
2
fractions ƒ that often results into irregularity patterns in PL emission intensity. The AIE
w
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
behavior of luminophore 2, 3 and 5 was further explored using absorption spectra (see SI
Figure S5). The formation of nanoparticles in suspension above 60% ƒ in 2 and above 50%
w
ƒw in 3 and 5 scatters the light leading to level off tails at longer wavelength of absorption
4
3
spectra. This effect of light scattering by nanoaggregates is known as “Mie scattering”. This
validates formation of nanoparticles and supports the fact that the emission at higher water
fraction is due to nanoaggregates. Theorefore, 2, 3 and 5 can termed as AIEgens.
Figure 7: SEM image of nanoparticles of 2 obtained in nanoparticle suspension containing
7
0% volume fraction of water (ƒ ) in THF.
w
In order to confirm formation of nanoaggregates at higher water fractions and to understand
size and morphology of aggregates, we subjected suspension of luminophore 2 in THF/water
mixture of 70% ƒ under scanning electron microscope (FEG-SEM). The SEM image of 2
w

New Journal of Chemistry
Page 16 of 38
1
2
3
4
5
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1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
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DOI: 10.1039/C9NJ06109F
(
Figure 7) in 70% ƒ display that aggregate formed are spherical in nature with mean diameter
w
of 31−68 nm. The nanosuspensions of aggregates of AIEgens are quite transparent and stable
for longer period of time without coalescence. This amazing stability of aggregates without
addition of surfactants attributed to polar carbonyl (C=O) group present in the molecules which
induces electronic repulsion and apparently prevents flocculation/coalescence of nanoparticles
in water.44
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Electrochemical Properties
The redox behaviour and HOMO and LUMO energy levels of dyes were evaluated by cyclic
voltammetry (CV) in DCM with ferrocene as an internal standard to calibrate the redox
potential and the pertinent data preserved in Table 3. The cyclic voltammogram of 4 and 5 are
presented in Figure 8 (for other compounds, see SI Figure S6).
Figure 8. Cyclic voltammogram (full scan) of compound 4 and 5 measured in anhydrous
dichloromethane.
On anodic sweep no oxidation peak was obtained for parent 1 whereas modulation of parent
molecule with different donor group show oxidation onset potential in the range of
0
.95 ‒1.28 eV for dyes 2−8. In cyclic voltammogram of 2−8, all the dyes exhibited two quasi-
reversible oxidation waves except dye 4, 6 and 8. Dye 4 and 6 display one reversible and one

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quasireversible oxidation wave. These two oxidation peak in CV attributed to oxidation of
diarylamine moiety in 2−5 and oxidation of phenothiazine and carbazole moiety in 6 and 7
respectively, corresponds to two electron processes while a single quasireversible wave was
observe for dye 8 assigned to oxidation of aliphatic morpholine. Further, cyclic voltammogram
of compounds 1−8 predominately display three quasireversible waves on cathodic sweep. In
this, two waves corresponds to reduction of phenazine core through two electron process and
one wave attributed to reduction of carbonyl group of benzoyl segment attached to phenazine
Table 3. Electrochemical and thermal data of 1‒8.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
퐩퐞퐚퐤a
퐩퐞퐚퐤b
HOMOc LUMOd
퐄퐂e
0
f
Compd
퐄
퐄
퐄
T ( C)
d
퐨퐱퐢
퐫퐞퐝
퐠
1
2
3
4
5
−
–0.89, ‒1.02, ‒1.39
‒0.94, 1.16, ‒1.53
−
‒3.67
‒3.63
‒3.66
‒3.59
‒3.70
−
330 (346)
377 (416)
427 (453)
412 (432)
198 (347)
1.23, 1.51
‒5.67
‒5.68
‒5.48
‒5.62
2.04
2.02
1.89
1.92
1.25, 1.53 ‒0.89, ‒1.15, ‒1.55
1.04, 1.57 ‒0.96, ‒1.21, ‒1.57
1.20,1.60 ‒0.87, ‒1.16, ‒1.34,
‒
1.51
6
7
0.95, 1.51 ‒0.89, ‒1.03, ‒1.49
1.20, 1.61 ‒0.87, ‒1.04, ‒1.37
‒5.39
‒5.62
‒5.68
‒3.66
‒3.71
‒3.68
1.73
1.91
2.00
252 (425)
334 (439)
357 (389)
8
1.28
‒0.92, ‒1.29, ‒1.48
aE oxidation peak potential (V). E reduction peak potential (V). HOMO energy level
peak
b
peak
c
oxi
red
peak
+
d
calculated from E
= −[ E – E
(Fc/Fc ) + 5.1 ] eV. LUMO energy level calculated
redox
= −[E – Eredox(Fc/Fc ) + 5.1] eV. E calculated from E = [HOMO ‒ LUMO]
HOMO
oxi
peak
+
e
EC
EC
from E
LUMO
red
g
g
f
eV. Decomposition temperature at 5% and 10% (in parentheses) weight loss derived by TGA.
core. Alongwith this, one additional reduction peak obtained for compound 5 could be assigned
to reduction of ‒NO group attached to diarylamine moiety.
2
The HOMO and LUMO energy levels were calculated by first oxidation and reduction
potential. The HOMO and LUMO energy levels of dyes 2−8 were found in the range of
‒
5.39 to ‒5.68 eV and ‒3.59 to ‒3.71 eV respectively. In order to commence ambipolar charge

New Journal of Chemistry
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1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
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5
5
5
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DOI: 10.1039/C9NJ06109F
transfer in material, it’s HOMO energy level should be below or equal to ‒5.0 eV and LUMO
2
8
levels must be less than ‒3.15 eV. Hence, the HOMO and LUMO values of 2−8 closely
matches to this requirement and comparable with reported ambipolar materials in literature like
small molecules: 6,13-bis(triisopropylsilylethynyl)-1,4,8,11-tetraazapentacene (TIPS-PEN)
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
4
5
(
HOMO = −5.49 eV; LUMO = −3.68 eV), Tyrian Purple (HOMO = −5.5 eV; LUMO = −3.8
eV),46 2,2’-bis{5-[2,5-(2-ethylhexyl)-6-(5-cyano-thiophene-2-yl)-pyrrolo[3,4-c]pyrrole-1,4-
4
7
dione-3yl]thiophene} (HOMO = −5.45 eV; LUMO = −3.74 eV), 1,4–diketo–2,5–dihexyl–
3
,6–bis(4–ethylendioxythienyl)phenyl)pyrrolo[3,4–c]pyrrole (HOMO = −5.40 eV; LUMO =
4
8
−
3.68 eV) and polymers such as Poly[2,6(4,4-bis-2-ethylhexyl)-4H-cyclopenta-[2,1-b-3,4-
b]dithiophene-alt-4,7(2,1,3-benzothiadazole) (PCPDTBT) (HOMO = −5.3 eV; LUMO = −3.55
eV),49 2,2’-bis{5-[2,5-(2-ethnylhexyl)-6-(5-cyano-thiophene-2-yl)pyrrolo[3,4-c]pyrrole-1,4-
dione-3-yl]thiophene} (DPP2CN) (HOMO = −5.45 eV, LUMO = −3.74 eV),50
Dithienocoronenedimide (DTCDI)-bithiophene copolymer (HOMO = −5.56 eV; LUMO =
51
−
3.70 eV). Thus, we can say dyes 2−8 could act as ambipolar materials in organic electronics.
These HOMO and LUMO energy levels were governed by nature of different donating unit
present in designed D−A system. The use of electron donating ‒OCH group and strong
3
electron donor phenothiazine responsible for comparatively higher HOMO level in 4
(
‒5.48 eV) and 6 (‒5.39 eV) respectively while presence of electron withdrawing ‒NO group
2
on diarlyamine in 5 (‒3.70 eV) possess lowest LUMO level compared to other derivatives. The
electrochemical band gap estimated falls in the range of 1.73−2.04 eV and closely matches
with optical band gap. It indicates that the electronic transitions from HOMO to LUMO level
were mainly due to intramolecular charge transfer taking place in the molecule. Compared to
other derivatives small band gap has obtained for dye 4 (1.89 eV) and 6 (1.73 eV) can assigned
to increased electron donating ability due to presence of ‒OCH group on diphenylamine and
3
strong electron donor phenothiazine. It’s found that the band gap is not solely depends on

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electron donating strength of the donor moiety but also affected by interaction between donor
and acceptor unit, stability of redox couple and steric factors in the molecule. Thus, the
comparatively narrower band gap for 6 (1.73 eV) than 4 (1.89 eV) can be attributed to photo-
induced charge separation occur in 6 due to presence of phenothiazine as a strong donor which
explained by PET process. This responsible for formation of stable radical cation on donor and
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
+
─
radical anion on acceptor (D + A → D + A ) entities, leads to shrinkage of band gap in the
5
2
molecule. Further, DFT/TD-DFT calculations supports the probability of PET charge transfer
and decrease in band gap due to photo-induced charge separation. These observations in cyclic
voltammetric studies display tuning of redox properties and importance of structure modulation
through changing donor on phenazine core in D−A system.
Theoretical properties
To elucidate relationship between ICT behaviours and molecular designs, the HOMO and
LUMO energy levels were theoretically calculated by geometrical optimization of ground and
excited states using the B3LYP/6-311++G** basis set implemented in Gaussian 03 program.53
Figure 9 show optimized geometries and theoretically calculated frontier molecular orbitals of
2
, 4 and 5 (for other compounds, see SI Figure S30−S42). The time dependent-density
functional (TD-DFT) calculations then performed to conclude and understand effect of
modulation of donor on photophysical properties of 2−8 and discussed herein detail.
The electron density distribution of frontier molecular orbital demonstrated that the parent
1 exhibit overlapped HOMO and LUMO orbital. The modulation with different donor in 2−8
results distinctly located HOMO and LUMO orbitals on donor segment and phenazine core
respectively. The electron density of HOMO is extended upto central phenazine core for all
derivatives except 6 whereas the LUMO orbitals in 2−8 are mainly residing on electron
deficient phenazine core and electron withdrawing carbonyl unit of benzoyl group attached to
the central core. The large twisting in 6 and 7 impairs the electronic coupling between donor

New Journal of Chemistry
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1
1
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2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
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DOI: 10.1039/C9NJ06109F
heterocyclic amines (phenothiazine, carbazole) and central acceptor phenazine core. These
leads to ineffective conjugation that results into maximum separation of HOMO and LUMO
which is responsible for weak D−A interaction and small dipole moments in 6 and 7.13b
Moreover, the HOMO in 6 is unambiguously located on one of the phenothiazene moiety.
This show strong electron donor phenothiazine undergo complete charge separation in ground
state. Also, dye 6 possess a small band gap. These both factors eventually supports
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
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1
2
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6
7
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9
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2
3
4
5
6
7
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9
0
5
4
intramolecular PET charge transfer in phenothiazine based derivative 6. However, dyes other
than 6 and 7 holds comparatively high dipole moments in the range of 5.11−9.27 Debye,
indicate that better charge transfer in the molecules. The large dipole moments in 4
(8.92 Debye) and 5 (9.27 Debye) assigned to polar ‒OCH and ‒NO group on triarylamine.
3
2
The computationally calculated energies of the HOMO–LUMO levels, HOMO‒LUMO
gap, vertical ionization potential, electron affinity and the ground state dipole moment for all
derivatives are given in Table 4. The HOMO and LUMO energy of 2–8 are in the range of
‒
5.07 to –6.04 eV and –2.49 to –3.14 eV respectively and to some extent comparable with
experimentally calculated energy levels. Additionally, theoretically obtained HOMO→LUMO
transitions of 2−8 helps to determined lowest energy S excitation and further confirm ICT
1
character in derivatives. The computationally calculated band gap are in the range
2
.21–3.13 eV and altered in accordance with the nature of donor moiety. So, the small band
gap obtained for dyes 4 (2.58 eV) and 6 (2.21 eV) attributed to good electron donating ability
of methoxy group on diarlyamine and phenothiazine respectively. Herein, narrower band gap
of 6 compared to 4 is because of large charge separation between donor and acceptor in 6 due
to PET. However, little increase of band gap in 5 (2.92 eV) and 8 (3.13 eV) corresponds to
electron withdrawing ‒NO group on diarylamine segment and aliphatic morpholine as a donor
2
moiety.

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1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 9. Optimized structures and Correlation diagram showing Frontier molecular orbitals
and energies of 2, 4 and 5.
The simulated absorption spectra then obtained by performing TD−DFT calculation in
implicit water using 6-311++G** basis set and presented in Figure 10. The transition energies,
oscillator strength and assignment for the most significant singlet excited states of molecules
are presented in Table 4 and other assignment are given in supporting information.

New Journal of Chemistry
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1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
Table 4. Computed Ionization potentials, Electron affinities, Wavelengths, Oscillator strengths, main vertical electronic transition in gas phase,
Orbital energies and Dipole moments of 1−8.
Compd
E (eV) I (eV) max
F
Assignments
EHOMO
eV)
ELUMO
(eV)
E (eV)
g
Dipole
(debye)
a
p
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
(
(nm)
1
2
1.91
1.59
7.91
6.36
406
00
573
555
0.7856 HOMO →LUMO (96%)
0.1436 HOMO–1→LUMO (96%)
0.7155 HOMO →LUMO (99%)
0.1515 HOMO–1→LUMO (99%)
0.3610 HOMO –1→LUMO+1 (92%)
0.7601 HOMO →LUMO (99%)
0.1433 HOMO–1 →LUMO (98%)
0.2602 HOMO →LUMO+1 (90%)
0.6358 HOMO →LUMO (98%)
0.2311 HOMO –1 →LUMO (98%)
0.2858 HOMO –1→LUMO+1 (96%)
1.0575 HOMO →LUMO (95%)
0.2170 HOMO–1→LUMO (82%)
0.0304 HOMO –2→ LUMO (83%)
0.0001 HOMO →LUMO (96%)
0.0001 HOMO–1 →LUMO (96%)
0.8393 HOMO–5 →LUMO (94%)
0.4202 HOMO →LUMO (96%)
0.0381 HOMO–4 →LUMO (93%)
–6.74
–5.41
–3.11
–2.67
3.62
2.73
2.33
6.25
4
4
12
3
4
5
6
1.53
1.43
2.16
2.00
6.32
5.98
6.97
6.38
557
–5.41
–5.07
–6.04
–5.36
–2.60
–2.49
–3.12
–3.14
2.81
2.58
2.92
2.21
6.50
8.92
9.27
3.65
5
4
34
21
622
6
4
04
41
534
18
5
394
605
5
3
99
93
7
8
1.92
1.48
6.78
6.88
510
394
501
–5.82
–5.76
–3.05
–2.63
2.77
3.13
2.34
5.11
0.8805 HOMO →LUMO (98%)
0.1170 HOMO–1 →LUMO (97%)
4
85

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The modulation with different donor on phenazine core affects simulated electronic
transitions in similar manner as observed in experimentally obtained photophysical properties.
Also, it show good oscillator strength for allowed as well as forbidden electronic transitions.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
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3
3
3
3
3
4
4
4
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4
4
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5
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5
5
5
5
5
5
5
6
0
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9
0
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9
0
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2
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9
0
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2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
*
*
The transitions below 400 nm assigned to n‒π and π‒π transitions and the transitions at longer
wavelength above 400 nm corresponds to characteristic ICT transitions of D−A interactions.
Figure 10. Simulated absorption spectra of compounds 1‒8 in implicit water.
Thermal properties
The thermal stability of 1‒8 were studied by thermogravimetric analysis (TGA) and melting
Figure 11. TGA thermogram of 2‒8 under nitrogen atmosphere at normal pressure. Heating
0
rate, 10 C/min.

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1
1
1
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1
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2
2
2
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2
2
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2
2
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3
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DOI: 10.1039/C9NJ06109F
point were determined by open capillary method. The TGA thermogram of 2‒8 are displayed
in Figure 11 (For 1, see SI Figure S43).
TGA thermogram of 2‒8 revealed that these dyes exhibit good thermal stability. The
decomposition temperature corresponds to 5% and 10% weight losses are found in the range
0
1
2
3
4
5
6
7
8
9
0
1
2
3
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9
0
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3
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5
6
7
8
9
0
0
0
1
98‒427 C and 347‒453 C respectively (Table 3). The order of thermal stability in
derivatives 2‒8 is 3 > 4 > 2 > 8 > 7 > 6 > 5. The high thermal stability make 2‒8 suitable for
their application in optoelectronics as it leads to enhanced life time of devices.
Conclusion
We have designed and synthesized seven novel D−A based derivatives by changing peripheral
donor unit on central phenazine core. Their optoelectrochemical, thermal and theoretical
properties were explored systematically. The photophysical properties were obviously
influenced by substitution with different donor segment. The D−A interaction originates ICT
character, which is confirmed by positive solvatochromism in emission. The optical properties
were tuned in such way that, it covers broad scale of fluorescence from cyan blue to red region
(
498−641 nm) in toluene, chloroform, DCM and neat solid film. The AIE studies for
luminophore 2, 3 and 5 reveal that recovery of emission at higher water fraction is due to
formation of stable nanoaggregate suspension. Electrochemically investigated HOMO and
LUMO are in the range ‒5.39 to ‒5.68 eV and ‒3.59 to ‒3.71 eV respectively and found
comparable with reported ambipolar materials. The unique electronic and geometric features
obtained by TD-DFT calculations verifies presence of D−A architecture in the molecules. Dyes
exhibit excellent thermal stability. Henceforth, all these features make dyes 2−8 the potential
candidate as emissive ambipolar materials in various optoelectronic applications.
Experimental Section
Chemicals and materials

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All the starting materials and reagents were purchased from commercial sources (Sigma
Aldrich and Alfa Aesar) and were used without any further treatment and purification unless
otherwise mentioned. The organic solvents were of HPLC and spectroscopic grade and were
dried and freshly distilled using the standard procedures and handled in a moisture-free
atmosphere. Column chromatography was carried out using SD-fine silica gel (60–120 mesh),
eluting with n-hexane and chloroform. The progress of the reaction and the purity of the
compound were checked by thin layer chromatography (TLC) on silica-gel-coated glass plates,
in which the spots were visualized with UV light (365 nm) and in an iodine chamber.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Instrumentation and methods
‒
6
‒1
UV-visible spectra were recorded in 10 mol L solutions in a 1 cm path length quartz cuvette
as well as the neat solid films on a SHIMADZU UV-2401PC instrument at room temperature.
The neat solid film of compounds 2–8 were prepared by using a spin coater (Holmarc
‒
1
HO-TH-05) at 1000 rpm for 2 min ∼6 mg mL of the sample in chloroform. Quartz plates
were used for the neat solid film studies. The excitation and emission spectra were carried out
on a Perkin Elmer LS 55 Fluorescence spectrophotometer. Cyclic voltammetry studies were
carried out on a computer-controlled Palmsens3 potentiostat. Typically, a three-electrode cell
equipped with a glassy carbon working electrode, a Ag/AgCl (non-aqueous) reference
electrode, and platinum (Pt) wire as the counter electrode was employed. The measurements
were carried at room temperature in anhydrous dichloromethane with tetra-butyl ammonium
hexafluorophosphate solution (0.1 M) as the supporting electrolyte with a scan rate of
‒1
1
00 mVs . The potential of the Ag/AgCl reference electrode was calibrated by using a
ferrocene/ferrocenium redox couple, which has the known oxidation potential of +5.1 eV. The
thermogravimetric analysis (TGA) were performed using a Metler Toledo instrument (TG)
1
13
under nitrogen atmosphere. H NMR and C NMR spectra were recorded using CDCl on
3
Varian 300 MHz Ultrashield spectrometer with tetramethylsilane (TMS) as internal reference

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1
1
1
1
1
1
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1
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2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
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at working frequency 300 MHz and 75 MHz respectively. Fourier trans-form infrared (FT–IR)
spectra were recorded on a Perkin Elmer Frontier 91579. Mass spectrometric measurements
were recorded using MALDI–TOF (Bruker) and elemental analysis was carried out on EA
Euro–elemental analysis instrument. To confirm formation of nanoparticle in AIE studies,
sample of synthesized dye subjected to field emission gun scanning electron microscopy (JEOL
JSM-7600F FEG−SEM).
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
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9
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1
2
3
4
5
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7
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9
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3
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8
9
0
Synthesis Procedures
Synthesis of (3,6-dibromodibenzo[a,c]phenazin-11-yl)(phenyl)methanone (1)
A
mixture of 3,4-diaminobenzophenone (0.8 g, 3.77 mmol) and 4,4′-
dibromophenanthroquinone (1.38 g, 3.77 mmol) was dissolved in 25 mL of glacial acetic acid
and refluxed for 3 hours. The reaction mixture was allowed to cool and then poured over
crushed ice to obtain mint green coloured solid. The obtained solid was then dried under
vacuum and purified using column chromatography (eluent: n-hexane:chloroform ratio as
0
-1
9
1
0:10), yellow-green solid. Yield 2.02 g (93%); mp 247 C. FT−IR, (KBr,  cm ): 3062,
max
1
633, 1587, 1321, 693; H NMR (300 MHz, CDCl ): δ 8.97 (dd, J = 9.0 Hz, 9.0 Hz, 2H), 8.53
3
1
3
(s, 1H), 8.42–8.21 (m, 4H), 7.97 (d, J = 9.0 Hz, 2H), 7.78–7.52 (m, 5H); C NMR (75 MHz,
CDCl ): δ 195.76 (C=O), 143.64, 142.18, 141.09, 138.32, 137.26, 132.93, 132.73, 132.29,
3
1
32.01, 131.71, 130.20, 129.86, 128.80, 128.62, 128.22, 127.94, 126.17, 125.89, 125.86.
+
MALDI-TOF: mass calcd for C H Br N O [M ]: 541.95, found: 541.88; elemental anal.
2
7
14
2
2
calcd for C H Br N O: C 59.81, H 2.60, Br 29.47, N 5.17, O 2.95. found: C 60.12, H 2.87,
2
7
14
2
2
Br 29.03, N 5.24, O 2.74.
General procedure for synthesis of 2−8
A mixture of compound 1 (0.2 g, 0.37 mmol) and various diarylamine/heterocyclic amines
(
0.125 g, 0.74 mmol) were dissolved in anhydrous toluene (50 mL). To this solution Pd (dba)
2 3
(
20 mg, 0.02 mmol), SPhos (25 mg, 0.048 mmol) and t-BuONa (75 mg, 0.75 mmol) were

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added. The reaction mixture was continuously stirred under nitrogen atmosphere at 100 C for
DOI: 10.1039/C9NJ06109F
8
−14 hours. Reaction mixture was then cooled to room temperature and extracted with
chloroform. The solid thus obtained was then purified by column chromatography (eluent:
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
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1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
n−hexane:chloroform ratio as 80:20) to obtain yellow to dark red solid.
3
,6-bis(diphenylamino)dibenzo[a,c]phenazin-11-yl)(phenyl)methanone (2)
0
-1
Yellow solid, yield: 164 mg (62%); mp 238 C. FT−IR (KBr,  cm ): 3062, 2919, 2850,
max
1
1
650, 1587, 1263, 693; H NMR (300 MHz, CDCl ): δ 9.11 (dd, J = 9.0 Hz, 9.0 Hz, 2H), 8.60
3
(
s, 1H), 8.38–8.23 (m, 2H), 7.97 (d, J = 6.0 Hz, 2H), 7.72–7.54 (m, 5H), 7.44–7.09 (m, 23H)
1
3
(1H extra due to residual CHCl in CDCl ); C NMR (75 MHz, CDCl ): δ 196.16 (C=O),
3
3
3
1
1
1
50.46, 150.20, 146.75, 143.70, 143.58, 143.39, 140.65, 137.60, 137.06, 133.48, 133.12,
32.74, 132.63, 130.19, 129.54, 129.51, 128.64, 128.48, 127.79, 127.40, 125.60, 125.50,
24.37, 124.25, 123.73, 123.65, 121.95, 121.75, 114.13, 113.90; MALDI-TOF: mass calcd for
+
C H N O [M ]: 718.27, found: 718.31; elemental anal. calcd for C H N O : C 85.21, H
5
1
34
4
51 34
4
4
.77, N 7.79, O 2.23 found: C 85.04, H 4.91, N 7.84, O 2.21.
(
3,6-bis(naphthalen-1-yl(phenyl)amino)dibenzo[a,c]phenazin-11-yl)(phenyl)methanone (3)
0
-1
Yellow solid, yield: 197 mg (65%); mp 187 C. FT−IR (KBr,  cm ): 3051, 2928, 2852,
max
1
1
654, 1596, 1263, 693; H NMR (300 MHz, CDCl ): δ 9.04 (dd, J = 9.0 Hz, 9.0 Hz, 2H), 8.54
3
(
d, J = 1.4 Hz, 1H), 8.29–8.18 (m, 2H), 8.05–7.71 (m, 8H), 7.69–7.00 (m, 26H) (1H extra due
1
3
to residual CHCl in CDCl ); C NMR (75 MHz, CDCl ): δ 196.04 (C=O), 150.96, 150.73,
3
3
3
1
1
46.97, 146.86, 142.37, 142.30, 140.53, 137.60, 136.93, 135.19, 133.55, 133.19, 132.70,
32.60, 130.98, 130.18, 129.33, 128.52, 128.46, 127.88, 127.46, 126.67, 123.88, 123.62,
123.47, 123.19, 123.11, 120.46, 120.27, 112.18, 112.01; MALDI-TOF: mass calcd for
+
C H N O [M ]: 818.30, found: 818.45; elemental anal. calcd for C H N O: C 86.53, H 4.68,
5
9
38
4
59 38
4
N 6.84, O 1.95 found: C 86.68, H 4.71, N 6.73, O 1.88.
3,6-bis(bis(4-methoxyphenyl)amino)dibenzo[a,c]phenazin-11-yl)(phenyl)methanone (4)
(

New Journal of Chemistry
Page 28 of 38
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2
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5
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7
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9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
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4
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4
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5
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5
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View Article Online
DOI: 10.1039/C9NJ06109F
0
-1
Dark red solid, yield: 165 mg (53.4%); mp 228 C. FT−IR (KBr,  cm ): 3070, 2928,
max
1
2
833, 1596, 1501, 1244, 1035, 825; H NMR (300 MHz, CDCl ): δ 9.01 (dd, J = 9.0 Hz, 6.0
3
Hz, 2H), 8.55 (s, 1H),8.34–8.16 (m, 2H), 7.94 (d, J = 6.0 Hz, 2H), 7.66–7.41 (m, 5H), 7.30–
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
7
3
.04 (m, 11H) (1H extra due to residual CHCl in CDCl ), 6.84 (dd, J = 3.0 Hz, 3.0 Hz, 8H),
3 3
1
3
.84 (s, 12H, −OCH ); C NMR (75 MHz, CDCl ): δ 196.23 (C=O), 156.66, 156.58, 151.15,
3
3
150.91, 143.89, 143.52, 140.46, 139.72, 139.62, 137.70, 136.70, 133.60, 133.21, 132.69,
1
1
32.54, 130.17, 129.36, 128.45, 128.31, 127.75, 127.32, 127.23, 122.38, 122.32, 119.73,
19.55, 114.80, 114.78, 111.37, 111.18, 55.42 (−OCH ); MALDI-TOF: mass calcd for
3
+
C H N O [M ]: 838.95, found: 838.39; elemental anal. calcd for C H N O C 78.74, H
5
5
42
4
5
55 42
4
5:
5
.05, N 6.68, O 9.54 found: C 78.81, H 4.97, N 6.80, O 9.42.
(
3,6-bis((4-nitrophenyl)(phenyl)amino)dibenzo[a,c]phenazin-11-yl)(phenyl)methanone (5)
0
-1
Yellow solid, yield: 207 mg (69.46%); mp 190 C. FT−IR (KBr,  cm ): 3062, 2919, 1587,
max
1
1
482, 1263, 1102, 693; H NMR (300 MHz, CDCl ): δ 9.26 (dd, J = 9.0 Hz, 9.0 Hz, 2H), 8.63
3
(
s, 1H), 8.41–8.25 (m, 2H), 8.06 (dd, J = 3.0 Hz, 3.0 Hz, 3H), 7.95 (d, J = 6.0 Hz, 2H), 7.81 (s,
1
3
2
H), 7.70–7.06 (m, 21H) (1H extra due to residual CHCl in CDCl ); C NMR (75 MHz,
3 3
CDCl ): δ 195.84 (C=O), 152.65, 152.65, 148.57, 148.35, 145.29, 141.54, 137.96, 137.30,
3
1
1
33.16, 132.88, 132.69, 130.23, 129.77, 129.49, 128.58, 128.49, 128.17, 127.02, 126.98,
26.49, 125.46, 124.78, 124.67, 120.48, 120.35, 117.86, 117.70; MALDI-TOF: mass calcd for
+
C H N O [M ]: 808.84, found: 808.26; elemental anal. calcd for C H N O : C 75.73, H
5
1
32
6
5
51 32
6
5
3
.99, N 10.39, O 9.89 found: C 75.84, H 4.03, N 10.10, O 10.03.
(
3,6-di(10H-phenothiazin-10-yl)dibenzo[a,c]phenazin-11-yl)(phenyl)methanone (6)
0
-1
Brown red solid, yield: 171 mg (60%); mp 162 C. FT−IR (KBr,  cm ): 3062, 2919, 2852,
max
1
1
654, 1587, 1255, 741; H NMR (300 MHz, CDCl ): δ 9.57 (dd, J = 9.0 Hz, 9.0 Hz, 2H), 8.73
3
(
s, 1H), 8.58–8.27 (m, 4H), 8.09–7.93 (m, 2H), 7.84–7.53 (m, 5H), 7.37–7.06 (m, 6H) (1H
extra due to residual CHCl in CDCl ), 7.02– 6.85 (m, 7H), 6.56 (dd, J = 6.0 Hz, 6.0 Hz, 4H);
3
3

Page 29 of 38
New Journal of Chemistry
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View Article Online
DOI: 10.1039/C9NJ06109F
C NMR (75 MHz, CDCl ) δ 195.86 (C=O), 144.84, 144.46, 143.88, 143.55, 143.44, 143.32,
3
1
42.92, 141.22, 138.24, 137.27, 134.38, 134.12, 134.09, 132.94, 132.83, 130.24, 129.95,
129.78, 129.09, 128.79, 128.66, 128.61, 128.46, 128.32, 127.43, 127.34, 127.05, 127.02,
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
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5
5
5
5
5
5
5
5
6
0
1
2
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4
5
6
7
8
9
0
1
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7
8
9
0
1
2
3
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7
8
9
0
1
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9
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3
4
5
6
7
8
9
0
1
23.72, 123.63, 123.48, 123.24, 122.26, 121.67, 118.51, 118.13; MALDI-TOF: mass calcd for
+
C H N OS [M ]: 778.19 found: 778.07; elemental anal. calcd for C H N OS : C 78.64, H
5
1
30
4
2
51 30
4
2
3
.88, N 7.19, O 2.05, S 8.23 found C 78.85, H 3.92, N 6.96, O 2.11, S 8.16.
(3,6-di(9H-carbazol-9-yl)dibenzo[a,c]phenazin-11-yl)(phenyl)methanone (7).
0
-1
Yellow solid, yield: 131 mg (50%); mp > 280 C. FT−IR (KBr,  cm ): 3062, 2919, 2842,
max
1
1654, 1607, 1216, 713; H NMR could not be obtained because of very poor solubility.
+
MALDI-TOF: mass calcd for C H N O [M ]: 714.24 found: 714.67; elemental anal. calcd
5
1
30
4
for C H N O: C 85.69, H 4.23, N 7.84, O 2.24 found: C 85.86, H 4.04, N 7.96, O 2.14.
5
1
30
4
(3,6-dimorpholinodibenzo[a,c]phenazin-11-yl)(phenyl)methanone (8).
0
-1
Red brown solid, yield: 165 mg (81%); mp 241 C. FT−IR (KBr, max cm ): 3062, 2912, 2852,
1
1
602, 1121, 702; H NMR (300 MHz, CDCl ): δ 9.20 (dd, J = 9.0 Hz, 9.0 Hz, 2H), 8.58 (s,
3
1
H), 8.37–8.20 (m, 2H), 7.96 (d, J = 9.0 Hz, 2H), 7.77 (s, 2H), 7.71–7.63 (m, 1H), 7.57 (t,
1
3
J = 7.4 Hz, 2H), 7.32 (t, J = 9.4 Hz, 2H), 3.99 (m, 8H, −OCH ), 3.46 (m, 8H, −NCH ); C
2
2
NMR (75 MHz, CDCl ): δ 196.23 (C=O), 153.11, 152.94, 143.53, 140.54, 137.65, 136.93,
3
1
33.78, 133.39, 132.74, 132.61, 130.18, 129.45, 128.49, 128.28, 127.88, 122.69, 116.50,
116.38, 106.92, 66.82 (−O(CH ) ), 48.56 (−N(CH ) ); MALDI-TOF: mass calcd for
2
2
2 2
+
C H N O [M ]: 554.23, found: 554.83; elemental anal. calcd for C H N O : C 75.79, H
3
5
30
4
3
35 30
4
3
5
.45, N 10.10, O 8.65 found: C 75.68, H 5.42, N 10.18, O 8.72.
Preparation of Nanoaggregates
-4
Stock THF solution of the dyes 2, 3, 5 and 7 with concentration 10 M were prepared. Aliquots
of stock solution were transferred to 5 mL volumetric flask. After dissolving dye in appropriate
-5
amount of THF, water was added drop wise under vigorous shaking to obtain 10 M solution