To what extent are the photophysical properties of quinoxaline- and quinoxalinone-based chromophores predictable?

Article abstract of DOI:10.1016/j.dyepig.2019.107580

A series of chromophores containing quinoxaline or quinoxalinone electron-acceptor (A) and dialkylaminostyryl electron-donor (D) units linked by π electronic bridge has been synthesized. Electronic emission and absorption spectra of the novel D-π-A, D-π-A-π-D or D-π-A-π-A-π-D systems cover a broad range from ultraviolet to near infrared. Positions and relative intensities of their absorption bands are shown to depend strongly on structural modifications of the molecules, while emission in solution strongly depends on both the structure of the solute and the solvent polarity. Quantum chemical modeling provided a reliable description of the observed absorption spectra and reproduced the positions of the emission bands. Quantum yields of emission are shown to be qualitatively predictable on the basis of empirical rules connecting the luminescence intensity with the chemical structures of both quinoxaline- and quinoxalinone-based luminopohores and the polarity of the solvents used. Theoretical assessment of the character of the main electronic transitions suggests that simultaneous presence of D and A units conjugated via π-bridges ensures the intramolecular charge-transfer effects probably underlying the observed similar solvatochromism for all the studied systems irrespective of their polarity.

Full text of DOI:10.1016/j.dyepig.2019.107580

Accepted Manuscript
To what extent are the photophysical properties of quinoxaline- and quinoxalinone-
based chromophores predictable?
Timur I. Burganov, Sergey A. Katsyuba, Liliya N. Islamova, Gusel M. Fazleeva, Sirina
M. Sharipova, Alexey A. Kalinin, Antonio Monari, Xavier Assfeld
PII:
S0143-7208(19)30900-3
DOI:
https://doi.org/10.1016/j.dyepig.2019.107580
Article Number: 107580
Reference:
DYPI 107580
To appear in: Dyes and Pigments
Received Date: 22 April 2019
Revised Date: 22 May 2019
Accepted Date: 22 May 2019
Please cite this article as: Burganov TI, Katsyuba SA, Islamova LN, Fazleeva GM, Sharipova SM,
Kalinin AA, Monari A, Assfeld X, To what extent are the photophysical properties of quinoxaline-
and quinoxalinone-based chromophores predictable?, Dyes and Pigments (2019), doi: https://
doi.org/10.1016/j.dyepig.2019.107580.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
To what extent are the photophysical properties of quinoxaline- and
quinoxalinone-based chromophores predictable?
Timur I. Burganov,*a Sergey A. Katsyuba,a Liliya N. Islamova,a Gusel M. Fazleeva,a Sirina M.
Sharipova,a Alexey A. Kalinin,a Antonio Monari,b Xavier Assfeld.b
a – Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Kazan,
Russia
b – University of Lorraine, CNRS, LPCT UMR 7019, F-54000 Nancy, France
* - corresponding author: timk90@mail.ru
Abstract
A series of chromophores containing quinoxaline or quinoxalinone electron-acceptor (A) and
dialkylaminostyryl electron-donor (D) units linked by π electronic bridge has been synthesized.
Electronic emission and absorption spectra of the novel D-π-A, D-π-A-π-D or D-π-A-π-A-π-D
systems cover a broad range from ultraviolet to near infrared. Positions and relative intensities of
their absorption bands are shown to depend strongly on structural modifications of the molecules,
while emission in solution strongly depends on both the structure of the solute and the solvent
polarity. Quantum chemical modeling provided a reliable description of the observed absorption
spectra and reproduced the positions of the emission bands. Quantum yields of emission are shown
to be qualitatively predictable on the basis of empirical rules connecting the luminescence intensity
with the chemical structures of both quinoxaline- and quinoxalinone-based luminopohores and the
polarity of the solvents used. Theoretical assessment of the character of the main electronic
transitions suggests that simultaneous presence of D and A units conjugated via π-bridges ensures
the intramolecular charge-transfer effects probably underlying the observed similar
solvatochromism for all the studied systems irrespective of their polarity.
Introduction
Organic molecules composed of electron-donor (D) and electron-acceptor (A) fragments
linked by π electronic bridge (D-π-A) are widely used in various applications such as non-linear
optical (NLO) materials,1-4 organic light-emitting diodes (OLEDs), 5-13, pH/polarity sensors14-21 and
light-harvesting components of organic solar cells.22-26 D-π-A systems often demonstrate a
remarkable sensitivity to structural modifications or environmental effects (solvatochromic shifts,
protonation/deprotonation color changes, thermochromism, galochromism, etc.). The introduction
and/or replacement of chemical substituents at different positions of the chromophore core allow
regulation of properties and functions of novel compounds. The further fine-tuning of these
properties can be achieved through the variation of the π-bridges between the D and A units.
Various aromatic heterocycles, such as thiophene,27-30 thiazole,31-34 pyrrole,35, 36 phenothiazine,37 and
various diazines,38 have been considered to date as π-linkers. In our recent works quinoxalinone

ACCEPTED MANUSCRIPT
(Qon) and quinoxaline (Q) derivatives extended this list,2, 39-45 and were tested as π-bridging
fragments for NLO-phores. Besides, Q derivatives were used in emissive layers of the OLEDs.46-52
Due to their π-deficient character Qs and Qons could act as electron-withdrawing units in π-
53, 54,55-57
conjugated push−pull structures. Similarly to other chromophores of this type,15-21,
emission of Q derivatives is highly sensitive to media effects.45 In addition, intramolecular charge
transfer (ICT), inherent for such systems, can induce tunable luminescence as well.
Typically the development of D-π-A systems is mainly based on trial and error approach
because of the absence of general schemes allowing the predictions of optical properties on grounds
of the chemical structures only. Quite recently44 we have tried to make a small step towards the
development of such a scheme for Qon-based D-π-A systems. Their absorption and emission turned
out to depend dramatically on simple variation of the position of the electron-donor N,N-
dimethylaminostyryl (DMAS) group relative to electron-acceptor Qon core.
In the present contribution we take the next step in the attempt to connect the chemical
structures of D-π-A systems in general, and diazines in particular, with their photophysical
properties. We provide a comprehensive study of a series of novel Q-based structural analogs of the
previously reported Qons44, possessing luminescent properties. Both families show quite similar
dependencies of their optical behavior on the observed structural variations, and in particular, on the
position of the DMAS moiety. This suggests that the spectra-structure correlations revealed earlier44
are not random in character, but are representative of inherent features of such chromophores. To
further check their generality we have also studied some other Q- and Qon-based systems of
different architecture, e.g. A-π-A, D-π-A-π-D or D-π-A-π-A-π-D.
In this respect, molecular model and simulation strategies could significantly help in guiding
the synthesis of fluorophores with targeted properties, and providing rationales for their
interpretation. On the basis of density functional theory (DFT) and time dependent DFT (TD-DFT)
quantum chemical calculations the experimental findings were reliably interpreted also in terms of
the nature of the excited states and of the electronic density reorganization. The accuracy and
reliability of the electron transition energies computed at both the ground (S0) and the first singlet
excited state (S1) equilibrium geometries with the use of hybrid PBE0 and long-range (LR)
corrected CAM-B3LYP functionals have also been assessed.
2. Results and discussion
2.1 Synthesis of dyes
Scheme 1 shows the synthesis of quinoxaline and quinoxalinone dyes 1-10 (Chart 1) with two, three
or four cyclic moieties. Knoevenagel condensation of 6- and 7-bromo-2-phenyl-3-
methylquinoxalines (11,12), 3,7-dimethyl-2-phenylquinoxalines (13), and 7-bromo-3-methyl-1-
propylquinoxalin-2-one (14) with p-N,N-dimethylaminobenzaldehyde leads to 3-styrylquinoxalines
1, 2, 5 and 16, respectively. The Heck reaction between compounds 11, 12, 14 and N,N-dialkyl-4-
vinylaniline produces 6(7)-aminostyrylquinoxaline derivatives 3, 4, 18 while the reaction of 1, 2, 16
with N,N-dialkyl-4-vinylaniline results in 6, 8, 9 containing two aminostyryl moieties. The oxidation
of quinoxalines 15 and 18 by selenium dioxide results in aldehydes 17 and 19 as major products and
dyes 7 and 10 as by-products, respectively. Furthermore bisquinoxalinones 7 and 10 have also been

ACCEPTED MANUSCRIPT
synthesized in moderate yields by condensation of methylquinoxalinones 15 and 18 with
quinoxalinonylcarbaldehydes 17 and 19, respectively. Coupling constants of the order of 16 Hz for
vinyl protons of compounds 5-10 in their 1H NMR spectra indicate that only trans-isomer is formed
in each case. The symmetrical structure of dyes 7 and 10 is confirmed by the presence of a single
singlet with double intensity in the 1H NMR spectra corresponding to the proton of the central vinyl
13
moiety, half the number of carbon signals in the C NMR spectra and also by [M+H]+ values in
their MALDI mass-spectra. It should be noted that dibutylamino moieties have been introduced to
increase the solubility in the organic solvents used.
Scheme 1. Synthesis of the chromophores. Reagents and Conditions: (i) p-Me2NC6H4CHO, Ac2O,
o
o
Py 1.5 h, 220 C or NaOH, H2O, Aliquat 336, 15-24 h, 100 C; (ii) p-Me2NC6H4CH=CH2 or p-
o
Bu2NC6H4CH=CH2, Pd(OAc)2, (o-Tol)3P, Et3N, DMF, 100-120 C, 4-24 h; (iii) SeO2, 60-70 min,
85-100 oC, argon, dioxane; (iv) Ac2O, 140 oC, 40 min. * - for the compound 16 an alternative name
2-Qon has been used for more convenience upon comparison with quionxaline-based analogue 2
(see the text).
2.2. Optical properties

ACCEPTED MANUSCRIPT
Steady-state electronic absorption and fluorescence spectra of 1-10 (Chart 1) have been
registered in solvents of different polarity (Figure 1). A rather moderate influence of solvent polarity
on the absorption spectral characteristics of 1-9 is clearly visible from Figure 1, while the emission
spectra reveal a notable positive solvatochromic behavior. Emission of D-π-A systems 1-5 covers a
wide spectral range of ca. 450-850 nm, while the longest-wave electronic absorptions maxima (λmax
)
are generally identified as the most intensive bands falling in a much narrower range of ca. 400-450
nm. The experimental data on λmax and emission maxima wavelengths (λemi) are collected in Table 1.
The absorption spectra of Qs 1-5 display three main bands, which differ mainly in their
relative intensities. The absorption spectra of isomers 1 and 2 almost superpose (Figure 1), being
simultaneously rather close to the spectrum of 2Qon – Qon-based structural analog of 2 (Figure S1).
The position of the DMAS group strongly influences the relative intensity of the second absorption
band (~360-362 nm) in the spectra of isomers 3, 4 and 5, but has only a minor impact on λmax values
and extinction coefficients (ɛ) of the lowest-energy absorption (Table 1). This is in contrast to the
case of analogous Qon-based systems, where the lowest-energy band dominates the spectra of
isomers 2Qon, 4Qon and 5Qon, but weak in the case of 3Qon (analog of 3) and thus is hidden under
the much brighter second lowest-energy band.44
Chart 1. Chemical structures of the compounds under study.

ACCEPTED MANUSCRIPT
diox
DCM
ACN
diox
DCM
ACN
1
1
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
300
350
400
450
500
550
600
500
550
550
550
600
650
700
750
800
850
λ, nm
λ, nm
diox
DCM
ACN
diox
2
2
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
DCM
ACN
300
350
400
450
500
550
600
500
600
650
700
750
800
850
λ, nm
λ, nm
diox
diox
DCM
ACN
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
3
3
DCM
ACN
300
350
400
450
500
550
450
500
600
650
700
750
800
850
900
λ, nm
λ, nm

ACCEPTED MANUSCRIPT
diox
DCM
ACN
diox
DCM
ACN
4
1.0
0.8
0.6
0.4
0.2
0.0
4
1.0
0.8
0.6
0.4
0.2
0.0
300
350
400
450
500
550
450
500
550
600
650
700
750
800
850
900
λ, nm
λ, nm
diox
DCM
ACN
diox
DCM
ACN
1.0
0.8
0.6
0.4
0.2
0.0
5
1.0
0.8
0.6
0.4
0.2
0.0
5
300
350
400
450
500
550
450
500
550
600
650
700
750
800
850
λ, nm
λ, nm
diox
DCM
ACN
diox
DCM
ACN
6
6
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
300
350
400
450
500
550
600
450
500
550
600
650
700
750
800
850
900
λ, nm
λ, nm

ACCEPTED MANUSCRIPT
diox
DCM
ACN
diox
DCM
ACN
7
7
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
300
350
400
450
500
550
450
500
550
600
650
700
λ, nm
λ, nm
diox
DCM
ACN
diox
DCM
ACN
8
8
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
300
350
400
450
500
550
600
450
500
550
600
650
700
750
800
850
900
λ, nm
λ, nm
diox
DCM
ACN
diox
DCM
ACN
9
9
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
550
600
650
500
550
600
650
700
750
800
850
900
λ, nm
λ, nm

ACCEPTED MANUSCRIPT
diox
DCM
diox
DCM
10
10
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
250 300 350 400 450 500 550 600 650 700
600
650
700
750
800
850
900
λ, nm
λ, nm
Figure 1. Experimental electronic absorption and emission spectra of solutions of 1-10 in three
solvents of different polarity (1,4-dioxane – diox, dichloromethane – DCM and acetonitrile –ACN).
Presented relative absorption/emission intensities were normalized to unity for the most intensive
bands.
Emission spectra of Qs 1-5 in 1,4-dioxane solutions are quite close to the corresponding
spectra of their Qon-based structural analogs 2Qon-5Qon (Figure S1): λemi for both series almost
coincide, except for the case of 4 (526 nm vs. 497 nm for 4Qon44), while the quantum yields (φ) of
Qs 1-5 differ only moderately from the corresponding values reported44 for 2Qon-5Qon (Table S1).
In particular, similarly to the case of 4Qon the maximal φ value is found for isomer 4. The rather
substantial solvatochromic shifts (∆λemi) of 1-5 are also similar to the ones reported for 2Qon-5Qon,
being maximal for acetonitrile solutions. The maximal similarity of ∆λemi is exhibited by the
structural analogs 4 / 4Qon: 0.26 / 0.27 and 0.43 / 0.45 eV for dichloromethane and acetonitrile,
respectively, and relative to 1,4-dioxane (the corresponding shifts in nm equal to 64 / 61 and 115 /
112 nm). The quantum yields of 4 / 4Qon also exhibit very similar dependencies on the solvent
polarity: 0.52 / 0.81, 0.21 / 0.62 and 0.01 / 0.03 for 1,4-dioxane, dichloromethane and acetonitrile
solutions, respectively. The same trend for these solutions is found also for 3 / 3Qon pair: 0.29 /
0.13, 0.09 / 0.03 and 0.01 / <0.01. Almost the same φ values are found for solutions of isomers 5 /
5Qon and their brominated derivatives 2 / 2Qon in 1,4-dioxane and dichloromethane. In contrast,
the fluorescence of 5 and 2 is almost quenched in acetonitrile, while only negligible differences in φ
values are found for dichloromethane and acetonitrile solutions of their structural analogs 2Qon and
5Qon (Table S1).
Table 1. Collected experimental photophysical data on the positions of the most long-wave
electronic absorption maxima (λmax), fluorescence maxima (λemi), Stokes shifts, extinction
coefficients (ε), and quantum yields (φ) measured for solutions of 1-10 in 1,4-dioxane,
dichloromethane (CH2Cl2) and acetonitrile (CH3CN).
compound
1,4-dioxane
CH2Cl2
CH3CN

ACCEPTED MANUSCRIPT
Stokes
shift
Stokes
shift
Stokes
shift
λmax
λemi
λmax
λemi
λmax
λemi
nm
eV
445
2.79
555
2.23
110
0.55
453
2.74
27900 0.17
453
601
2.06
148
0.67
448
2.77
27700 0.01
448
643
1.93
195
0.84
1
2
ε / φ 26500 0.14
nm
eV
445
2.79
555
2.23
110
0.55
602
2.06
149
0.68
648
1.91
200
0.85
2.74
2.77
ε / φ 24800 0.19
27500 0.17
27500 0.01
nm
eV
415
2.99
526
2.36
111
0.63
407
3.05
596
2.08
189
0.97
407
3.05
646
1.92
239
1.13
3
ε / φ 30200 0.29
28700 0.09
25800 0.01
nm
eV
403
3.08
526
2.36
123
0.72
408
3.04
590
2.10
182
0.94
400
3.10
641
1.93
241
1.17
4
ε / φ 24700 0.52
23800 0.21
25500 0.01
nm
eV
430
2.88
528
2.35
98
0.54
436
2.84
571
2.17
135
0.67
433
2.86
614
2.02
181
0.84
5
ε / φ 29100 0.13
28800 0.18
28500 0.04
nm
eV
458
2.71
540
2.30
82
0.41
468
2.65
627
1.98
159
0.67
462
2.68
650
1.91
188
0.78
6
ε / φ 44700 0.17
48500 <0.01
45600 <0.01
nm
eV
434
2.86
484
2.56
50
0.30
434
2.86
490
2.53
56
0.33
431
2.88
502
2.47
71
0.41
7
ε / φ 33300 0.20
20000 0.21
33100 0.15
nm
eV
475
2.61
549
2.26
74
0.35
482
2.57
615
2.02
133
0.56
487
2.55
661
1.88
174
0.67
8
ε / φ 52700 0.44
53800 0.24
54000 0.02
nm
eV
481
2.58
559
2.22
78
0.36
494
2.51
611
2.03
117
0.48
488
2.54
651
1.90
163
0.64
9
ε / φ 54200 0.26
63300 0.20
64100 0.04
nm
eV
528
2.35
630
1.97
102
0.38
549
2.26
74300 0.01
736
1.68
187
0.58
-
-
-
-
-
-
-
-
10
ε / φ 82800 0.18
Close similarity of luminescence of Q- and Qon-based fluorophores seems to be typical not
only for D-π-A, but also for D-π-A-π-D systems: λemi for the newly synthesized Q and Qon
derivatives 8 and 9, respectively, almost coincide for all the solvents, and φ values differ only
moderately, hence 8 and 9 demonstrate very similar solvatochromic behavior. Moreover, the
solvatochromic effects found for these D-π-A-π-D systems are practically the same as the ones for
D-π-A systems 1-5 discussed above. Interestingly, all the quantitative characteristics of
luminescence for compounds 8 and 4 (Table 1) differ rather negligibly. Thus, the inclusion of
dibutylaminostyryl (DBAS) substituent to Q core in 8 instead of methyl group in 4 has only a minor
impact on the emission of the Q derivatives. Strikingly similar dependencies of the optical properties

ACCEPTED MANUSCRIPT
of D-π-A and D-π-A-π-D systems on the position of the D unit relative to Q core are also observed
when comparing D-π-A isomers 3 and 4 and their D-π-A-π-D analogs 6 and 8. The positions of
DBAS moiety in 6 and 8 are the same as the positions of DMAS group in 3 and 4, respectively,
resulting in similar quantum yields φ: in 1,4-dioxane solutions φ (6) and φ (3) amount to 0.17 and
0.29, respectively, while for isomers 8 and 4 φ values increase up to 0.44 and 0.52, respectively. The
same close parallelism of the φ values for these pairs of isomers is also evident for dichloromethane
and acetonitrile (Table 1).
The expansion of the conjugated π-system in 6, 8 and 9 as compared to the structurally
related D-π-A species 3, 4 and 5 results in the red shifts of absorption maxima (λmax) by ca. 0.3-0.5
eV (30-78 nm) and an almost two-fold increase of the extinction coefficients (ɛ) (Table 1). To assess
the possible impact of a further elongation of the conjugation on the photophysical behavior the D-
π-A-π-A-π-D chromophore 10 have been synthesized. The bathochromic shift found for this
compound relative to 9 amounts to 0.23-0.25 eV (47-55 nm), while ɛ increases by ca. 20-50%
(Table 1, Figure 1). In contrast, the absorption of A-π-A system 7, i.e. an analog of 10 for whom the
bridge’s conjugation pattern has been shortened, is blue-shifted relative to 9 by ca. 0.3 eV (46 nm)
while ɛ decreases by ca. 60%, clearly demonstrating that origin of the aforementioned strong
bathochromic effects is not connected to the presence of A-π-A core in 10. The emission of 10 also
differs dramatically from the fluorescence spectrum of 7: λemi and φ of the former strongly depend
on solvent polarity, while the photophysical characteristics of the latter remain almost constant for
all solutions.
To better understand the observed photophysical behavior of 1-10 quantum chemical
calculations have been performed. Electronic absorption spectra simulated with the use of hybrid
PBE0 functional (Figure 2, Table 2) satisfactorily reproduce the experimental results. The energies
of the first vertical electronic transitions, S0→S1, are predicted by PBE0 gas-phase calculations
almost quantitatively, though being slightly underestimated in some cases. Globally, the deviations
from the corresponding experimental values found for 1,4-dioxane solutions do not exceed 0.17 eV.
However, if the PBE0 simulations well reproduce the positions of the absorption bands the accuracy
of the predictions of their relative intensities is less remarkable (Figure 2).
1.0
abs in Dioxane
calculations
(CAM-B3LYP)
abs in Dioxane
calculations (PBE0)
2
2
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
550
600
250
300
350
400
450
500
550
600
λ, nm
λ, nm

ACCEPTED MANUSCRIPT
1.0
0.8
0.6
0.4
0.2
0.0
1.6
abs in Dioxane
calculations (PBE0)
abs in Dioxane
3
3
calculations
(cam-B3LYP)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
550
600
650
250
300
350
400
450
500
550
600
650
λ, nm
λ, nm
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
abs in Dioxane
calculations (PBE0)
4
4
abs in Dioxane
calculations
(cam-B3LYP)
250
300
350
400
450
500
550
600
650
250
300
350
400
450
500
550
600
650
λ, nm
λ, nm
0.8
0.6
0.4
0.2
0.0
1.2
abs in Dioxane
calculations (PBE0)
abs in Dioxane
calculations
(CAM-B3LYP)
5
5
1.0
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
550
600
250
300
350
400
450
500
550
600
λ, nm
λ, nm
abs in Dioxane
calculations (PBE0)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
abs in Dioxane
calculations
(CAM-B3LYP)
1.8
6
6
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
550
600
250
300
350
400
450
500
550
600
λ, nm
λ, nm

ACCEPTED MANUSCRIPT
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.6
abs in Dioxane
calculations (PBE0)
abs in diox
calculations
(CAM-B3LYP)
7
7
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
550
600
250
300
350
400
450
500
550
600
λ, nm
λ, nm
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
abs in Dioxane
calculations
(CAM-B3LYP)
abs in Dioxane
calculations (PBE0)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
8
8
250
300
350
400
450
500
550
600
650
700
250
300
350
400
450
500
550
600
650
700
λ, nm
λ, nm
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
abs in Dioxane
calculations
(CAM-B3LYP)
abs in Dioxane
calculations (PBE0)
9
9
250
300
350
400
450
500
550
600
650
250
300
350
400
450
500
550
600
650
λ, nm
λ, nm
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
0.0
3.2
abs in Dioxane
calculations (PBE0)
abs in Dioxane
calculations
(CAM-B3LYP)
10
10
2.8
2.4
2.0
1.6
1.2
0.8
0.4
0.0
250 300 350 400 450 500 550 600 650 700 750 800
250 300 350 400 450 500 550 600 650 700 750 800
λ, nm
λ, nm

ACCEPTED MANUSCRIPT
a
b
Figure 2. Absorption spectra of the compounds under study. Experimental spectra (black) are
registered for solutions in 1,4-dioxane. Gas-phase spectra simulated with the use of PBE0/def2-
TZVP (a) and CAM-B3LYP/def2-TZVP (b) methods (red lines) are obtained by broadening of the
vertical straight lines by Gaussian functions with a full-width at half maximum of 0.4 eV. All the
electronic transitions calculated with CAM-B3LYP/def2-TZVP have been red-shifted (0.4-0.5 eV)
to better match the experimental spectra. The heights of the vertical straight lines correspond to the
calculated oscillator strengths of the corresponding vertical transitions.
Since the electronic excited states of systems with D-π-A architecture are often characterized
by, at least partial, ICT character, we have considered the use of the LR-corrected CAM-B3LYP
functional, to assess one of the common source of errors experienced by conventional hybrid
functionals. It should be mentioned that an alternative reason of the computational errors could be
related to the absence of vibronic transitions consideration (for details see58). As already reported59
LR functionals and CAM -B3LYP systematically overestimate the electron transition energies by ca.
0.3-0.5 eV (Table 2), as a consequence and to facilitate the comparison of the simulated spectra with
their experimental counterparts, the calculated absorption bands in Figure 2.b are shifted so that the
positions of the lowest-energy absorptions in the theoretical and experimental spectra coincide for
each molecule under study. After such correction the CAM -B3LYP simulations reproduce even the
minor spectral features appearing as shoulders in the 300-400 nm spectral region. Indeed, such an
60,
accurate description of the spectral bands shape is important for predictions of chemical colours
61. Nevertheless, the intensities of all the bands relative to the lowest-energy absorption band (λmax
)
are systematically underestimated by CAM-B3LYP calculations. It should be noted that according
to both functionals (Figure 2 a and b) and for all the compounds, the minimum energy band should
be ascribed to only one isolated vertical transition (i.e. S0→S1) displaying the largest (the second
largest in the only case of 4) oscillator strength (f). Such pattern is also typical for closely related
Qons, 2Qon, 4Qon and 5Qon, though excited states of a qualitatively different character was found
for 3Qon 44 (vide supra). Noteworthy, both functionals also preview qualitatively similar trends for
the dependence of the S0→S1 oscillator strengths on the chromophore structure (Table 2), this trends
being in general agreement with the experiment (see ε values in Table 1)
Table 2. Characteristics of vertical electronic transitions calculated at optimized geometries of
ground (S0) and first singlet excited (S1) states in comparison to experimental values
Experiment in 1,4-
Com-
pound
Error,c
eV
dioxanea and
acetonitrileb
Calculations
λmax,
nm/
eV
λemi,
nm/
eV
Stokes
shift,
eV
d
µS0 ,
∆Eabs/
∆Eemi
Stokes
shift, eV
S0→
S1
S1→S0
D
0.56a
gas PBE0
7.40
445/
555/
2
2.79a 2.23a
fe
0.638
0.347
0.35
-0.01/

ACCEPTED MANUSCRIPT
0.19
E, nm
E, eV
447
2.77
511
2.43
448/
648/
0.85b
2.77b 1.91b
PCM Acetonitrile PBE0
1.062
fe
0.796
491
2.52
-0.24/
0.23g
E, nm
E, eV
580
10.27
0.38
2.14
gas CAM-B3LYP
1.055
fe
1.019
376
3.30
0.51/
0.61
E, nm
E, eV
436
2.84
6.68
gas PBE0
4.40
0.46
fe
0.906
440
2.82
0.903
486
-0.17/
0.20
E, nm
E, eV
0.27
2.55
415/
526/
0.63a
1.13b
PCM Acetonitrile PBE0
1.448
2.99a 2.36a
fe
0.984
479
2.59
3
-0.46/
0.22g
E, nm
E, eV
579
5.82
0.45
407/
646/
3.05b 1.92b
2.14
gas CAM-B3LYP
1.436
fe
1.306
362
3.43
0.44/
0.50
E, nm
E, eV
434
2.86
3.39
gas PBE0
4.13
0.57
fe
0.503
420
2.95
0.244
487
-0.12/
0.19
E, nm
E, eV
0.41
2.55
403/
526/
0.72a
1.17b
PCM Acetonitrile PBE0
0.919
3.08a 2.36a
fe
0.643
455
2.73
4
-0.37/
0.34g
E, nm
E, eV
545
5.49
0.45
400/
641/
3.10b 1.93b
2.28
gas CAM-B3LYP
1.533
fe
1.341
342
3.62
0.55/
0.75
E, nm
E, eV
399
3.11
3.36
gas PBE0
4.25
0.52
fe
0.624
429
2.89
0.375
491
0.01/
0.18
E, nm
E, eV
0.36
430/
528/
0.54a
0.84b
2.88a 2.35a
2.53
PCM Acetonitrile PBE0
1.106
5
fe
0.777
471
2.64
433/
614/
2.86b 2.02b
-0.23/
0.20g
E, nm
E, eV
558
6.32
0.41
2.22
gas CAM-B3LYP

ACCEPTED MANUSCRIPT
fe
0.980
367
3.38
1.029
428
2.90
0.50/
0.55
E, nm
E, eV
3.81
gas PBE0
5.13
0.48
0.24
fe
0.883
469
2.64
0.761
515
2.41
-0.06/
0.11
E, nm
E, eV
458/
540/
PCM Acetonitrile PBE0
1.346
2.71a 2.30a
0.41a
0.78b
fe
1.011
520
2.39
6
-0.30/
0.15g
E, nm
E, eV
602
7.59
0.33
462/
650/
2.68b 1.91b
2.06
gas CAM-B3LYP
1.435
fe
1.392
384
3.23
0.52/
0.55
E, nm
E, eV
4.43
gas PBE0
0.31
0.39
436
2.84
fe
1.079
447
2.77
1.188
515
-0.09/
-0.15
E, nm
E, eV
0.36
2.41
434/
484/
0.30a
0.41b
PCM Acetonitrile PBE0
1.572
2.86a 2.56a
fe
1.216
469
2.64
7
-0.24/
-0.47g
E, nm
E, eV
620
0.24
0.64
431/
502/
2.88b 2.47b
2.00
gas CAM-B3LYP
1.264
fe
1.185
390
3.18
0.32/
-0.01
E, nm
E, eV
485
2.56
0.28
gas PBE0
1.54
0.62
fe
1.560
476.0
2.60
1.637
525.6
2.36
0.01/
0.10
E, nm
E, eV
0.25
475/
549/
0.35a
0.67b
PCM Acetonitrile PBE0
2.327
2.61a 2.26a
fe
1.717
530
2.34
8
-0.21/
0.04g
E, nm
E, eV
647
1.92
0.42
487/
661/
2.55b 1.88b
1.92
gas CAM-B3LYP
2.069
fe
1.976
395
3.14
0.53/
0.40
E, nm
E, eV
466
2.66
1.11
gas PBE0
2.75
0.47
481/
559/
0.36a
0.64b
fe
2.096
490
2.53
2.205
547
2.58a 2.22a
9
-0.05/
0.05
E, nm
E, eV
0.26
488/
651/
2.27

ACCEPTED MANUSCRIPT
2.54b 1.90b
PCM Acetonitrile PBE0
2.620
695
1.78
gas CAM-B3LYP
2.176
fe
2.197
545
2.28
-0.27/
-0.12g
E, nm
E, eV
4.08
0.49
fe
2.184
415
2.99
0.41/
0.26
E, nm
E, eV
501
2.48
2.89
gas PBE0
0.94
0.51
fe
2.647
578
2.14
2.949
655
-0.20/
-0.08
E, nm
E, eV
0.25
1.89
PCM Acetonitrile PBE0
3.356
fe
2.635
676
1.83
528/
630/
0.38a
10
2.35a 1.97a
-
E, nm
E, eV
887
1.34
0.43
1.40
gas CAM-B3LYP
2.952
fe
2.936
453
2.74
0.39/
0.21
E, nm
E, eV
0.97
0.56
568
2.18
a – 1,4-dioxane was chosen as the least polar solvent for a better comparison with gas-phase calculations;
b – acetonitrile was used for comparison with PCM calculations;
c – errors for absorption/emission (
λmax λemi and respective calculated ES0→S1/ES1→S0 values:
ES1→S0 λmax λemi for comparison with gas-phase computations are taken from the corresponding experiments
∆Eabs/∆Eemi) represent the energy difference in eV between experimental
/
∆
Eabs λmax(eV) – ES0→S1 and Eemi λemi(eV) –
=
∆
=
.
/
for 1,4-dioxane solutions, while PCM computations are compared with the experiments for acetonitrile
solutions of all compounds except 10, which is insoluble in acetonitrile.
d – dipole moment calculated at the ground state (S0) geometry.
e – oscillator strength.
The energies of the vertical S1→S0 transitions (ES1→S0) computed at the first singlet excited
state (S1) in vacuo optimized geometries with the use of PBE0 functional are slightly overestimated
by ca. 0.2 eV relative to the experimental emission energies for all the D-π-A compounds (2-5) in
the least polar 1,4-dioxane. Smaller, but less systematic deviations of -0.15-0.11 eV from the
experiment are found for compounds 6-10. It should be noted that similar reasonably good accuracy
was demonstrated by analogous PBE0 computations for a broad variety of phospholes 62.
As mentioned above, the deviations of transition energies obtained with the use of CAM-
B3LYP functional from the corresponding experimental values are more pronounced and
systematical. Mean values of ∆Eabs and ∆Eemi (Table 2) amount to 0.46 and 0.42 eV, respectively. If
the corresponding systematic shifts are subtracted from the overestimated computed transition
energies, standard deviations (SD) of the corrected CAM-B3LYP energies from absorption and
emission experiment for 1,4-dioxane solutions amount to 0.08 and 0.23 eV for ES0→S1 and ES1→S0
respectively.
,

ACCEPTED MANUSCRIPT
In order to computationally assess the experimentally observed solvatochromism, the
polarizable continuum model (PCM) with standard parameters for acetonitrile has been applied.
According to Figure S2 (ESI) such an implicit treatment of solvent effects has only a moderate
impact on the shape of the simulated absorption bands producing only parallel and systematically
overestimated red shifts of their positions (Table 2). At the same time, the PCM results for emission
are in reasonable accordance with the experimental data reported on solvatochromism. Linear
response PCM fails only in the case of the almost non-polar molecule 7 (cf. dipole moments in
Table 2): indeed PCM computations strongly overestimate the red shift for λemi of 7 in acetonitrile
solutions (Table 2). Formally only state-specific solvation models can provide a physically sound
description of the polarization response of the environment during photon emission, but these
models come at a significantly increased computational cost. In the present case, the LR
approximation seems sufficient for our purposes , with the exception of 7, providing significant
improvement in the description of the emission spectral properties for acetonitrile solutions.
Deviations of ca. 0.2-0.3 eV found for the computed ES1→S0 values from the corresponding
experimental emission energies are comparable to those found for the gas-phase computations
relative to the measured for 1,4-dioxane solutions (vide supra).
To analyze in more details the nature of the first low-lying excited states the natural
transition orbitals (NTOs) have been considered (Figure 3 and Figure S3 in ESI). The NTOs for the
first electronic excitation are presented in Figure 3. Additionally the ICT has been semi-
63-65
quantitatively assessed using the recently introduced quantum mechanical descriptor ꢀꢁ
based
on the topological analysis of detachment/attachment transition density matrices (for more details
see the computational section). Here we only remind that ꢀꢁ close to unity corresponds to pure local
transition, while a value of zero represents a pure and long-range charge transfer state.
compound
Occupied NTO
Virtual NTO
2
ꢀꢁ = 0.60

ACCEPTED MANUSCRIPT
3
ꢀꢁ = 0.64
4
ꢀꢁ = 0.56
N
N
N
Ph
5
ꢀꢁ = 0.63
6
ꢀꢁ = 0.68
7
ꢀꢁ = 0.83

ACCEPTED MANUSCRIPT
8
ꢀꢁ = 0.79
9
ꢀꢁ = 0.74
10
ꢀꢁ = 0.77
Figure 3. NTOs for the first electronic excitation S0→S1. NTOs have been plotted with threshold
value equal to 0.03.
The visual analysis of the NTOs clearly demonstrates the participation of delocalized π-orbitals
spread on all the fragments of the molecule simultaneously, hence the transitions can be safely
classified as π→π*. For all the compounds, except the A-π-A system 7, the electronic density is
transferred from the entire π-conjugated system delocalized over the whole backbone of the
molecule (occupied NTO) to the more electron-withdrawing Q or Qon moieties (virtual NTO),
hence giving a partial ICT state. An almost negligible participation of the π orbitals of the Ph
moieties at Q cores is also seen in Figure 3. These qualitative observations are confirmed by the
analysis of ꢀꢁ indexes varying within 0.56-0.79 for 2-6, 8-10, which points to partial ICT character
of the transition. The maximal value of ꢀꢁ = 0.83 calculated for 7 is indicative of a more local
character of the S0→S1 transition. The less preeminence of ICT for the S1 state of this molecule
probably explains its peculiarly weak solvatochromism also registered for emission spectrum. It
should be noted that for 6 and 8 - 10 all the electronic transitions include a transfer from all D
fragments simultaneously to Q or Qon acceptor units (Figure 3). That is, in spite of architecture
different from strongly polar D-π-A systems 1-5, even low-polar molecules 8-10 demonstrate a

ACCEPTED MANUSCRIPT
partial charge transfer in the S1 state relative to S0 state, this probably being a basis of similarity of
the solvatochromic effects found for 1-5 and 6, 8 - 10. Note also that the relatively large values of
ꢀꢁ point to only partial charge-transfer character and in particular justify the relative good behavior
of hybrid functionals as compared to long-range corrected ones.
Conclusions
We have introduced a series of novel quinoxaline- and quinoxalinone-based chromophores
absorbing and emitting radiation in a broad range spanning from the UV to the NIR. The positions
and relative intensities of their absorption bands are shown to depend strongly on the structural
modifications of the molecules. Quantum chemical calculations within the framework of TD-DFT
approach provided reliable theoretical description of the observed spectral features. In particular, the
energies of the S0→S1 excitations were predicted with accuracy to ca. ±0.1 eV.
The positions and intensities of emission bands in the spectra in solution strongly depend on
both the structure of the solute and the polarity of the solvent. As expected, the precision of the
computational determination of the excitation energies for the S1→S0 transitions in this case is
lowered to ca. ±0.2 eV. The reliable theoretical prediction of quantum yields (φ) of emission is all
the more difficult, and we have to rely on empirical rules connecting the chemical structures of
luminophores and their luminescence. Present study suggests that φ values of various Q- and Qon-
based systems of D-π-A, D-π-A-π-D or D-π-A-π-A-π-D architecture depend on the positions of the
electron-donor N,N-dialkylaminostyryl groups relative to electron-acceptor Q or Qon moieties in a
rather similar way. Moreover, solvatochromic effects found for similar isomeric forms of a rather
broad variety of structures turned out to be qualitatively the same. The theoretical assessment of the
character of the main electronic transitions suggests that the simultaneous presence of electron-
donor and -acceptor units conjugated via π-bridges favors a partial ICT effect probably underlying
the similarity of solvatochromism for all the studied systems irrespective of the concrete type of D-
A architecture.
The capability of the chosen quantum chemical methods and empirical spectra-structure
correlations to reproduce the relation between the structure and the photophysical properties of a
rather broad variation of Q- and Qon-based chromophores suggests the possible use of combination
of the both approaches as a predictive tool in the rational design of the related chromophores
presenting improved optical and photophysical features.
3. Experimental and computational details
3.1. Materials and instrumentation
The IR, NMR, UV–vis, MALDI spectra were registered on the equipment of Assigned Spectral-
Analytical Center of FRC. Infrared (IR) spectra were recorded on the Bruker Vector-22 FT-IR
spectrometer. All NMR experiments were performed with Bruker AVANCE-600 and AVANCE-
1
13
400 (600 and 400 MHz for H NMR, 150 and 100 MHz for C NMR) spectrometers. Chemical

ACCEPTED MANUSCRIPT
shifts (δ, in ppm) are referenced to the solvent (CDCl3 or acetone-d6). The mass spectra were
obtained on Bruker UltraFlex III MALDI TOF/TOF instrument with p-nitroaniline as a matrix. The
melting points of compounds 5-10 were determined on a Boetius hot-stage apparatus. Compounds
1-4, 11, 12, 14, 16, 18 and 19 were obtained according to literature [41, 43]. Electronic absorption
(UV-Vis) and steady state fluorescence spectra were recorded at room temperature on a Perkin-
Elmer Lambda 35 spectrometer and a Cary Eclipse Fluorescence Spectrophotometer (Varian),
respectively, using 10 mm quartz cells. Absorption spectra were registered with a scan speed of 480
nm/min, using a spectral width of 1 nm. All samples were prepared as solutions in three solvents:
1,4-dioxane (Dioxane), dichloromethane (CH2Cl2/DCM), acetonitrile (CH3CN) with the
concentrations ranging from ~10–5 to ~10−4 mol L-1. The absorbance at excitation wavelength was
less than 0.1 to avoid the “inner filter effect”. Fluorescence quantum yields were measured using
aqueous solution of quinine sulfate (λex = 350 nm, φ = 0.57 in 0.1 M H2SO4) and Rhodamine 6G (λex
= 530 nm, φ = 0.92 in H2O) as the standards. Appropriate corrections were made for the optical
density of the solutions and the refractive index of the medium 66
3.2 Synthesis of
(E)-3-(4-(dimethylamino)styryl))-7-methyl-2-phenylquinoxalin (5)
A
mixture of 3,7-dimethyl-2-phenylquinoxaline (13) (100 mg, 0.43 mmol), N,N-
dimethylaminobenzaldehyde (65 mg, 0.43 mmol), Aliquat 336 (14 mg, 0.42 mmol) and aqueous
sodium hydroxide (5M, 2 mL) was refluxed for 24 h. The reaction mixture was cooled, and
extracted with CH2Cl2. The organic layer was separated, washed with water, dried over anhydrous
MgSO4 and filtered. The solvent was removed at reduced pressure, and the residue was purified by
silica gel column chromatography (eluent petroleum ether – EtOAc, 100:1) to give compound 5 (70
1
mg). Yield 45%, red-orange powder. Rf=0.32 (hexane : ethyl acetate=10:1); mp 119–120 °C. H
NMR (600 MHz, acetone-d6): δ 7.99 (d, J=15.4 Hz, 1H, H ethene), 7.90 (d, J=8.2 Hz, 1H, H-5
quinoxaline), 7.84 (s, 1H, H-8 quinoxaline), 7.76 (d, J=7.8 Hz, 2H, o-Ph), 7.62-7.54 (m, 4H, m,p-Ph,
H-6 quinoxaline),7.40 (d, J=8.6 Hz, 2H, 3,5-H aniline), 7.18 (d, J=15.6 Hz, 1H, H ethene), 6.73 (d,
J=8.6 Hz, 2H, 2,6-H aniline), 3.0 (s, 6H, Me), 2.60 (s, 3H, Me). 13С NMR (150 MHz, acetone-d6): δ
154.1, 152.2, 150.2, 142.6, 141.1, 140.2, 140.0, 137.5, 131.8, 130.6, 129.7, 129.6, 129.1, 128.3,
125.4, 120.1, 113.0, 40.2, 21.8. IR (νmax, cm−1, KBr): 3024 (C-H), 2917 (C-H), 2854 (C-H), 2804(C-
H), 1601 (C=N, C=C), 1522 (C=C), Elemental Analysis for C25H23N3: found C, 82.06; H, 6.29; N,
11.56%, requires C, 82.16; H, 6.34; N, 11.50%.
3.3 Synthesis of dyes 6, 8 and 9
A mixture of bromoquinoxalines 1, 2, 16 (0.12 mmol), N,N-dibutyl-4-vinylaniline (27 mg, 0.12
mmol), tri(о-tolyl)phosphine (4.0 mg, 0.012 mmol), Pd(OAc)2 (1.3 mg, 0.006 mmol), Et3N (0.30 g,
0.30 mmol), and anhydrous DMF (1 mL) was stirred for 4 h at 120 °C. The reaction mixture was
cooled, poured into water, and extracted with CH2Cl2. The organic layer was separated, washed with
water, dried over anhydrous MgSO4 and filtered. The solvent was removed at reduced pressure, and
the residue was purified by silica gel column chromatography (eluent petroleum ether – EtOAc,
100:1→15:1) to give compounds 6, 8, 9, respectively.

ACCEPTED MANUSCRIPT
3.3.1 6-((E)-4-(Dibutylamino)styryl)-3-((E)-4-(dimethylamino)styryl)-2-phenylquinoxaline (6)
Yield 33% (23 mg), red-orange powder. Rf=0.52 (hexane : ethyl acetate=10:3); mp 179–180 °C. 1H
NMR (600 MHz, CDCl3): δ 8.04 (s, 1H, H-5 quinoxaline), 7.99 (d, J=15.5 Hz, 1H, H ethene), 7.98
(d, J=8.7 Hz, 1H, H-7 quinoxaline), 7.87 (d, J=8.7 Hz, 1H, H-8 quinoxaline), 7.75 (d, J=7.5 Hz, 2H,
o-Ph), 7.54 (dd, J=7.5, 7.3 Hz, 2H, m-Ph), 7.50 (dd, J=7.3, 7.3 Hz, 1H, p-Ph), 7.46 (d, J=8.7 Hz, 2H,
3,5-H aniline), 7.44 (d, J=8.7 Hz, 2H, 3,5-H aniline), 7.27 (d, J=16.2 Hz, 1H, H ethene), 7.18 (d,
J=15.5 Hz, 1H, H ethene), 7.08 (d, J=16.2 Hz, 1H, H ethene), 6.69 (d, J=8.7 Hz, 2H, 2,6-H aniline),
6.67 (d, J=8.7 Hz, 2H, 2,6-H aniline), 3.32 (t, J=7.6 Hz, 4H, NCH2), 3.00 (s, 6H, Me), 1.64–1.59 (m,
4H, NCH2CH2), 1.42–1.35 (m, 4H, N(CH2)2CH2), 0.98 (t, J=7.5 Hz, 6H, CH3). 13С NMR (150
MHz, CDCl3): δ 153.0, 150.9, 149.9, 148.3, 142.4, 140.4, 140.1, 139.0, 136.7, 131.4, 129.7, 129.03,
129.00, 128.8, 128.5, 128.2, 127.1, 125.0, 124.8, 124.1, 122.7, 120.0, 112.1, 111.7, 50.8, 40.3, 29.5,
20.4, 14.0. IR (νmax, cm−1, KBr): 2956 (C-H), 2927 (C-H), 2871 (C-H), 1501 (C=N, C=O), 1517
(C=C). MALDI-TOF: 581 [M+H]+, Elemental Analysis for C40H44N4: found C, 82.81; H, 7.58; N,
9.71%, requires C, 82.72; H, 7.64; N, 9.65%.
3.3.2 7-((E)-4-(Dibutylamino)styryl)-3-((E)-4-(dimethylamino)styryl)-2-phenylquinoxaline (8)
Yield 41% (29 mg), red-orange powder. Rf=0.52 (hexane : ethyl acetate=10:3); mp 115–116 °C. 1H
NMR (600 MHz, CDCl3): δ 8.03 (s, 1H, H-8 quinoxaline), 8.02 (d, J=8.7 Hz, 1H, H-6 quinoxaline),
7.98 (d, J=15.6 Hz, 1H, H ethene), 7.94 (d, J=8.7 Hz, 1H, H-5 quinoxaline), 7.76 (d, J=7.3 Hz, 2H,
o-Ph), 7.55 (dd, J=7.3, 7.3 Hz, 2H, m-Ph), 7.52 (dd, J=7.3, 7.3 Hz, 1H, p-Ph), 7.45 (d, J=8.8 Hz, 2H,
3,5-H aniline), 7.43 (d, J=8.8 Hz, 2H, 3,5-H aniline), 7.25 (d, J=16.2 Hz, 1H, H ethene), 7.18 (d,
J=15.6 Hz, 1H, H ethene), 7.06 (d, J=16.2 Hz, 1H, H ethene), 6.68 (d, J=8.7 Hz, 2H, 2,6-H aniline),
6.66 (d, J=8.7 Hz, 2H, 2,6-H aniline), 3.32 (t, J=7.3 Hz, 4H, NCH2), 3.00 (s, 6H, Me), 1.64–1.57 (m,
4H, NCH2CH2), 1.42–1.35 (m, 4H, N(CH2)2CH2), 0.98 (t, J=7.3 Hz, 6H, CH3). 13С NMR (150
MHz, CDCl3): δ 154.3, 150.8, 148.6, 148.2, 141.5, 141.3, 139.1, 139.0, 136.3, 131.1, 129.7, 128.9,
128.8, 128.6, 128.4, 128.2, 127.9, 125.3, 125.0, 124.1, 122.7, 120.0, 112.1, 111.7, 50.8, 40.2, 29.5,
20.3, 14.0. IR (νmax, cm−1, KBr): 2953 (C-H), 2924 (C-H), 2857 (C-H), 1597 (C=N, C=O), 1519
(C=C). MALDI-TOF: 581 [M+H]+, Elemental Analysis for C40H44N4: found C, 82.79; H, 7.70; N,
9.69%, requires C, 82.72; H, 7.64; N, 9.65%.
3.3.3 7-((E)-4-(Dibutylamino)styryl)-3-((E)-4-(dimethylamino)styryl)-1-propylquinoxalin-2(1H)-one
(9).
1
Yield 28% (19 mg), dark-red powder. Rf=0.40 (hexane : ethyl acetate=10:3); mp 113–115 °C. H
NMR (400 MHz, CDCl3): δ 8.06 (d, J=16.0 Hz, 1H, H ethene), 7.75 (d, J=8.4 Hz, 1H, H-5
quinoxaline), 7.59 (d, J=8.8 Hz, 2H, 3,5-H aniline), 7.56 (d, J=16.0 Hz, 1H, H ethene), 7.50 (dd,
J=8.4, 1.4 Hz, 1H, H-6 quinoxaline), 7.42 (d, J=8.7 Hz, 2H, 3,5-H aniline), 7.21 (d, J=1.4 Hz, 1H,
H-8 quinoxaline), 7.13 (d, J=16.2 Hz, 1H, H ethene), 6.95 (d, J=16.2 Hz, 1H, H ethene), 6.71 (d,
J=8.8 Hz, 2H, 2,6-H aniline), 6.65 (d, J=8.7 Hz, 2H, 2,6-H aniline), 4.29 (t, J=7.8 Hz, 2H, NCH2),
3.31 (t, J=7.6 Hz, 4H, NCH2), 3.02 (s, 6H, Me), 1.92–1.82 (m, 2H, NCH2CH2), 1.64–1.54 (m, 4H,
NCH2CH2), 1.42–1.33 (m, 4H, N(CH2)2CH2), 1.11 (t, J=7.4 Hz, 3H, CH3), 0.97 (t, J=7.3 Hz, 6H,

ACCEPTED MANUSCRIPT
CH3). 13С NMR (100 MHz, CDCl3): δ 155.2, 151.5, 151.1, 148.3, 139.3, 138.0, 133.1, 132.3, 131.0,
129.7, 129.4, 128.2, 125.1, 123.9, 122.7, 121.0, 117.7, 112.1, 111.7, 110.9, 50.8, 43.7, 40.2, 29.5,
20.7, 20.3, 14.0, 11.5. IR (νmax, cm−1, KBr): 2956 (C-H), 2928 (C-H), 2871 (C-H), 1648 (C=O),
1595 (C=N, C=C), 1521 (C=C). MALDI-TOF: 563 [M+H]+, Elemental Analysis for C37H46N4O:
found C, 78.82; H, 8.30; N, 9.91%, requires C, 78.96; H, 8.24; N, 9.96%.
3.4 Synthesis of dyes 7 and 10
Method I. A mixture of 3-methylquinoxalin-2-one 15 or 18 (1.50 mmol), selenium dioxide (196 mg,
1.76 mmol) and dioxane (6 mL) was stirred at 100 °C for 1 h under argon and then cooled to room
temperature. After removal of the solvent by rotary-evaporation, the residue was purified by silica-
gel column chromatography (eluent petroleum ether – EtOAc, 30:1→2:1) to give aldehyde 17 or 19
as major product and bis-quinoxalinones 7 or 10 as by-product, respectively.
Method II. A mixture of 3-methylquinoxalin-2-one 15 or 18 (0.11 mmol), aldehyde 17 or 19 (0.13
mmol), respectively, and acetic anhydride (1 mL) was stirred at 140 °C for 40 min and then cooled
to room temperature. After removal of the solvent by rotary-evaporation, the residue was purified by
silica-gel column chromatography (eluent petroleum ether – EtOAc, 30:1→3:1).
3.4.1 (E)-1,2-Bis(7-methyl-1-propylquinoxalin-2(1H)-on-3-yl)ethene (7)
Yield 4% (13 mg, method I), 24% (11 mg, method II); yellow powder. Rf=0.23 (hexane : ethyl
1
acetate=10:3); mp 268–279 °C. H NMR (400 MHz, CDCl3): δ 8.57 (s, 2H, H ethene), 7.78 (d,
J=8.1 Hz, 2H, H-5 quinoxaline), 7.15 (d, J=8.1 Hz, 2H, H-6 quinoxaline), 7.07 (s, 2H, H-8
quinoxaline), 4.25 (t, J=7.7 Hz, 4H, NCH2), 2.52 (s, 6H, Me), 1.86–1.79 (m, 4H, NCH2CH2), 1.07
13
(t, J=7.3 Hz, 6H, CH3). С NMR (100 MHz, CDCl3): δ 154.9, 151.0, 141.2, 132.6, 132.1, 130.6,
130.4, 125.1, 113.6, 43.7, 22.3, 20.6, 11.4. IR (νmax, cm−1, KBr): 3089 (CH), 2959 (CH), 2874
(CH), 1650 (C=O), 1609 (C=N, C=C), 1572 (C=C). MALDI-TOF: 429 [M+H]+, 451 [M+Na]+, 467
[M+K]+, Elemental Analysis for C26H28N4O2: found C, 72.91; H, 6.62; N, 13.10% requires C, 72.87;
H, 6.59; N, 13.07%.
3.4.2 (E)-1,2-Bis(7-((E)-4-(dibutylamino)styryl)-1-propylquinoxalin-2(1H)-on-3-yl)ethene (10)
Yield 5% (32 mg, method I), 33% (31 mg, method II); violet powder. Rf=0.26 (hexane : ethyl
1
acetate=10:3); mp 245–246 °C. H NMR (400 MHz, CDCl3): δ 8.53 (s, 2H, H ethene), 7.78 (d,
J=8.4 Hz, 2H, H-5 quinoxaline), 7.50 (dd, J=8.4, 1.2 Hz, 2H, H-6 quinoxaline), 7.40 (d, J=8.8 Hz,
4H, 3,5H aniline), 7.17 (d, J=1.2 Hz, 2H, H-8 quinoxaline), 7.14 (d, J=16.2 Hz, 2H, H ethene), 6.93
(d, J=16.2 Hz, 2H, H ethene), 6.63 (d, J=8.8 Hz, 4H, 2,6-H aniline), 4.28 (t, J=7.6 Hz, 4H, NCH2),
3.31 (t, J=7.7 Hz, 8H, NCH2), 1.91–1.81 (m, 4H, NCH2CH2), 1.64–1.56 (m, 8H, NCH2CH2), 1.42–
13
1.33 (m, 8H, N(CH2)2CH2), 1.11 (t, J=7.4 Hz, 6H, CH3), 0.98 (t, J=7.4 Hz, 12H, CH3). С NMR
(100 MHz, CDCl3): δ 155.0, 150.3, 148.4, 140.8, 133.2, 133.0, 131.8, 130.9, 130.2, 128.3, 123.7,
122.5, 121.1, 111.6, 110.8, 50.8, 43.7, 29.5, 20.6, 20.3, 14.0, 11.5. IR (νmax, cm−1, KBr): 2955 (C-H),
2925 (C-H), 2856 (C-H), 1657 (C=O), 1590 (C=N, C=C), 1519 (C=C). MALDI-TOF: 859 [M+H]+,
881 [M+Na]+, Elemental Analysis for C56H70N6O2: Found C, 78.39; H, 8.17; N, 9.72% requires C,
78.28; H, 8.21; N, 9.78%.
3.4.3 7-Methyl-1-propylquinoxalin-2(1H)-one-3-carbaldehyde (17)

ACCEPTED MANUSCRIPT
1
Yield 73%(239 mg), yellow powder. Rf = 0.09 (hexane : ethyl acetate=10:3); mp 138–140 °C. H
NMR(400 MHz, CDCl3): 10.45 (s, 1Н, СНО), 7.94 (d, J=8.3 Hz, 1Н, H-5), 7.24 (dd, J=8.3 Hz, 1.1
Hz, 1Н, H-6), 7.14 (s, 1Н, Н-8), 4.25 (t, J=7.8 Hz, 2Н, NСН2), 2.56 (s, 3Н, СН3), 1.77-1.87 (m, 2Н,
СН2СН3), 1.08 (t, J=7.4 Hz, 3Н, CH3). 13С NMR (100 MHz, CDCl3): δ 189.5, 154.5, 145.8, 145.6,
134.2, 132.6, 131.4, 126.0, 113.9, 43.5, 22.6, 20.6, 11.3. IR (νmax, cm−1, KBr): 3073 (CH), 3045
(CH), 2963 (CH), 2933 (CH), 2874 (CH), 1704 (C=O), 1652 (C=O), 1606 (C=N, C=C), Elemental
Analysis for C13H14N2O2: Found C, 67.74; H, 6.09; N, 12.11%, requires C, 67.81; H, 6.13; N,
12.17%.
3.4.4 (E)-7-(4-(Dibutylamino)styryl)-1-propylquinoxalin-2(1H)-one-3-carbaldehyde (19).
Yield: 68% (455 mg) [41].
3.5 Synthesis of 3,7-Dimethyl-1-propylquinoxalin-2-one (15)
In three-neck round bottom flask ethanol (1L) was added, then a solution of 4-methyl-1,2-
diaminobenzene (27.40 g, 224 mmol) in ethanol (0.5 L) and a solution of ethyl pyruvate (26.10 g,
224 mmol) in ethanol (0.5 L) were added dropwise for 3 h at room temperature under stirring. The
reaction mixture was stirred for 6 h and left overnight in a refrigerator at temperature of 10oC.
Precipitated crystals were filtered, washed with ethanol. Isomeric mixture (17.0 g) of 3,7-, and 3.6-
dimethylquinoxalin-2(1H)-ones of 5:1 ratio (according to 1H NMR spectrum) was obtained. Ethanol
was evaporated from the filtrate under reduced pressure, the precipitate was washed with ethanol.
Isomeric mixture (17.5 g) of 3,7 -, and 3.6-dimethylquinoxalin-2(1H)-ones of 1:1 was obtained.
Total yield 88%. A suspension of isomeric mixture of 3,7- and 3,6-dimethylquinoxalin-2(1Н)-ones
(12.0 g, 69 mmol), КOH (7.75 g, 138 mmol), and dioxane (40 ml) was stirred for 2 minutes at 100
°C and then cooled. The solution of PrI (14.05 g, 83 mmol) in dioxane (20 ml) was added. The
reaction mixture was stirred for 4 h at 100 °C, then cooled, poured into water and extracted with
CH2Cl2. The organic layer was dried over Na2SO4, filtered, and evaporated under reduced pressure.
The isomers mixture (14.2 g, yield 95%) was obtained. 3,7-dimethyl derivative 12 was isolated by
the fourfold recrystallization from hexane. Yield 29% (4.12 g), white powder. Rf = 0.40
1
(ethylacetate: hexane = 1:3); mp 66-67 °С (hexane). H NMR (acetone-d6): 7.59 (d, J=8.1 Hz 1Н,
H5), 7.33 (s, 1Н, Н8), 7.13 (dd, J=8.1, 1.0 Hz, 1Н, H6), 4.20 (t, J=7.7 Hz, 2Н, NСН2), 2.48 (s, 3Н,
13
СН3), 2.43 (s, 3Н, СН3), 1.70-1.79 (m, 2Н, СН2СН3), 1.09 (t, J=7.4 Hz 3Н, CH3). С NMR (100
MHz, acetone-d6): δ 156.6, 154.6, 139.9, 132.6, 131.0, 129.1, 124.1, 114.0, 43.0, 21.0, 20.5, 20.4,
10.6. IR (Nujol mull), ν, cm–1:1649 (C=O), 1613 (C=N, C=C), 1566 (C=C). Elemental Analysis for
C13H16N2O: found C, 72.00; H, 7.39; N, 13.05%, requires C, 72.19; H, 7.46; N, 12.95; O, 7.40%.
3.7. Computational details
All density functional theory (DFT) calculations were performed with the Gaussian 09
program package.67 In general the spherical def2-TZVP atomic orbital (AO) basis set was used 68, 69
All the structures were optimized with the use of hybrid PBE0 functional70, 71 and long-range
corrected CAM-B3LYP72 functional. The nature of S0→Sn transitions (n = 1, 2, 3) has been

ACCEPTED MANUSCRIPT
characterized by the analysis of the NTOs supported by the quantitative topological analysis based
on the detachment/attachment density matrices63-65, 73. We remind that the NTO representation
allows to consider any TD-DFT electronic excited state as a transition from the first (occupied) NTO
to the second (virtual) orbital, as a consequence the occupied NTO should be considered as
representative of the hole density, while the virtual NTO will describe the particle density. Excited
states topology was analyzed by a post processing of the Gaussian output performed using the
NANCY_EX 2.0 software suite,74 in order to obtain natural transition orbitals (NTOs) and ꢀꢁ index.
Stationary points were characterized as minima by frequency analyses. Solvent effects on the
photophysical properties have been taken into accounts using the polarizable continuum model
(PCM)75-79 within linear-response (LR) implemented in Gaussian 09 software. Time-dependent
density functional response theory (TD-DFT)80-82 has been employed to compute the vertical
excitation energies (i.e., absorption and emission wavelengths) and oscillator strengths on the
ground state (GS/S0) and first singlet excited state (S1) equilibrium geometries, each optimized in
the gas phase as well as with the use of PCM model with standard parameters for acetonitrile as a
solvent. No energy shift has been applied for PBE0 while for CAM-B3LYP calculations all the
excitations energies have been red-shifted by an error factor computed as the difference between
ES0→S1 and corresponding experimental λmax in order to better match experimental spectral curves.
Simulated electronic absorption spectra, calculated as 20 vertical excitations at the optimized ground
state (GS) geometries were empirically broaden by single Gaussian type functions with full-width at
half maximum (FWHM) equals to 0.4 eV. The dipole length representation is used to calculate
oscillator strengths discussed in the present paper.
Acknowledgments
The reported study was funded by Russian Science Foundation (project № 18-73-00165). The
authors gratefully acknowledge the CSF-SAC FRC KSC RAS for providing necessary facilities to
carry out an experimental part of this work. Some of the calculations were performed on the LPCT
local computational resources.
References
1.
T. Yamada, I. Aoki, H. Miki, C. Yamada and A. Otomo, Materials Chemistry and Physics, 2013, 139,
699-705.
2.
3.
S. M. Sharipova and A. A. Kalinin, Chemistry of Heterocyclic Compounds, 2017, 53, 36-38.
M. Ashraf, A. Teshome, A. J. Kay, G. J. Gainsford, M. D. H. Bhuiyan, I. Asselberghs and K. Clays, Dyes
and Pigments, 2013, 98, 82-92.
4.
Y. J. Cheng, J. D. Luo, S. Hau, D. H. Bale, T. D. Kim, Z. W. Shi, D. B. Lao, N. M. Tucker, Y. Q. Tian, L. R.
Dalton, P. J. Reid and A. K. Y. Jen, Chemistry of Materials, 2007, 19, 1154-1163.
C. W. Tang and S. A. Vanslyke, Applied Physics Letters, 1987, 51, 913-915.
M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson and S. R. Forrest, Nature,
1998, 395, 151-154.
5.
6.
7.
S. F. Chen, L. L. Deng, J. Xie, L. Peng, L. H. Xie, Q. L. Fan and W. Huang, Advanced Materials, 2010, 22,
5227-5239.

ACCEPTED MANUSCRIPT
8.
J. H. Huang, J. H. Su, X. Li, M. K. Lam, K. M. Fung, H. H. Fan, K. W. Cheah, C. H. Chen and H. Tian,
Journal of Materials Chemistry, 2011, 21, 2957-2964.
9.
J. H. Huang, J. H. Su and H. Tian, Journal of Materials Chemistry, 2012, 22, 10977-10989.
K. Walzer, B. Maennig, M. Pfeiffer and K. Leo, Chemical Reviews, 2007, 107, 1233-1271.
B. W. D'Andrade and S. R. Forrest, Advanced Materials, 2004, 16, 1585-1595.
J. Kido, K. Hongawa, K. Okuyama and K. Nagai, Applied Physics Letters, 1994, 64, 815-817.
J. Kido, M. Kimura and K. Nagai, Science, 1995, 267, 1332-1334.
10.
11.
12.
13.
14.
S. Achelle, J. Rodriguez-Lopez, C. Katan and F. Robin-le Guen, Journal of Physical Chemistry C, 2016,
120, 26986-26995.
15.
16.
D. Liu, Z. Y. Zhang, H. Y. Zhang and Y. Wang, Chemical Communications, 2013, 49, 10001-10003.
V. Schmitt, S. Moschel and H. Detert, European Journal of Organic Chemistry, 2013, 2013, 5655-
5669.
17.
18.
19.
C. Wink and H. Detert, Journal of Physical Organic Chemistry 2013, 26, 137-143.
P. Singh, A. Baheti and K. R. J. Thomas, Journal of Organic Chemistry, 2011, 76, 6134-6145.
S. Achelle, A. Barsella, C. Baudequin, B. Caro and F. R. L. Guen, Journal of Organic Chemistry, 2012,
77, 4087-4096.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
S. Achelle, I. Nouira, B. Pfaffinger, Y. Ramondenc, N. Ple and J. Rodriguez-Lopez, Journal of Organic
Chemistry, 2009, 74, 3711-3717.
S. Achelle, J. Rodriguez-Lopez and F. Robin-le Guen, Journal of Organic Chemistry, 2014, 79, 7564-
7571.
J. Q. Zhang, Y. J. Zhang, J. Fang, K. Lu, Z. Y. Wang, W. Ma and Z. X. Wei, Journal of the American
Chemical Society, 2015, 137, 8176-8183.
H. Kang, W. Lee, J. Oh, T. Kim, C. Lee and B. J. Kim, Accounts of Chemical Research, 2016, 49, 2424-
2434.
R. Y. Zhao, C. D. Dou, Z. Y. Xie, J. Liu and L. X. Wang, Angewandte Chemie-International Edition,
2016, 55, 5313-5317.
S. J. Liu, Z. P. Kan, S. Thomas, F. Cruciani, J. L. Bredas and P. M. Beaujuge, Angewandte Chemie-
International Edition, 2016, 55, 12996-13000.
L. Y. Yang, S. Q. Zhang, C. He, J. Q. Zhang, H. F. Yao, Y. Yang, Y. Zhang, W. C. Zhao and J. H. Hou,
Journal of the American Chemical Society, 2017, 139, 1958-1966.
H. T. Turan, Y. Eken, M. Marazzi, M. Pastore, V. Aviyente and A. Monari, Journal of Physical
Chemistry C, 2016, 120, 17916-17926.
C. Z. Cai, I. Liakatas, M. S. Wong, M. Bosch, C. Bosshard, P. Gunter, S. Concilio, N. Tirelli and U. W.
Suter, Organic Letters, 1999, 1, 1847-1849.
S. R. Hammond, O. Clot, K. A. Firestone, D. H. Bale, D. Lao, M. Haller, G. D. Phelan, B. Carlson, A. K. Y.
Jen, P. J. Reid and L. R. Dalton, Chemistry of Materials, 2008, 20, 3425-3434.
A. J. P. Akelaitis, B. C. Olbricht, P. A. Sullivan, Y. Liao, S. K. Lee, D. H. Bale, D. B. Lao, W. Kaminsky, B.
E. Eichinger, D. H. Choi, P. J. Reid and L. R. Dalton, Optical Materials, 2008, 30, 1504-1513.
X. H. Ma, F. Ma, Z. H. Zhao, N. H. Song and J. P. Zhang, Journal of Materials Chemistry, 2009, 19,
2975-2985.
X. H. Ma, F. Ma, Z. H. Zhao, N. H. Song and J. P. Zhang, Journal of Materials Chemistry, 2010, 20,
2369-2380.
S. Beckmann, K. H. Etzbach, P. Kramer, K. Lukaszuk, R. Matschiner, A. J. Schmidt, P. Schuhmacher, R.
Sens, G. Seybold, R. Wortmann and F. Wurthner, Advanced Materials, 1999, 11, 536-+.
R. Andreu, E. Galan, J. Orduna, B. Villacampa, R. Alicante, J. T. L. Navarrete, J. Casado and J. Garin,
Chemistry-a European Journal, 2011, 17, 826-838.
Q. Q. Li, C. G. Lu, J. Zhu, E. Fu, C. Zhong, S. Y. Li, Y. P. Cui, J. G. Qin and Z. Li, Journal of Physical
Chemistry B, 2008, 112, 4545-4551.
F. G. Liu, H. R. Wang, Y. H. Yang, H. J. Xu, M. L. Zhang, A. R. Zhang, S. H. Bo, Z. Zhen, X. H. Liu and L.
Qiu, Journal of Materials Chemistry C, 2014, 2, 7785-7795.

ACCEPTED MANUSCRIPT
37.
38.
39.
40.
M. J. Cho, J. Y. Kim, J. H. Kim, S. H. Lee, L. R. Dalton and D. H. Choi, Bulletin of the Korean Chemical
Society, 2005, 26, 77-84.
M. Klikar, P. le Poul, A. Ruzicka, O. Pytela, A. Barsella, K. D. Dorkenoo, F. R. L. Guen, F. Bures and S.
Achelle, Journal of Organic Chemistry, 2017, 82, 9435-9451.
A. A. Kalinin, S. M. Sharipova, T. I. Burganov, Y. B. Dudkina, A. R. Khamatgalimov, S. A. Katsyuba, Y.
H. Budnikova and M. Y. Balakina, Dyes and Pigments, 2017, 146, 82-91.
A. A. Kalinin, S. M. Sharipova, T. I. Burganov, A. I. Levitskaya, O. D. Fominykh, T. A. Vakhonina, N. V.
Ivanova, A. R. Khamatgalimov, S. A. Katsyuba and M. Y. Balakina, Journal of Photochemistry and
Photobiology a-Chemistry, 2019, 370, 58-66.
41.
O. D. Fominykh, A. A. Kalinin, S. M. Sharipova, A. V. Sharipova, T. I. Burganov, M. A. Smirnov, T. A.
Vakhonina, A. I. Levitskaya, A. A. Kadyrova, N. V. Ivanova, A. R. Khamatgalimov, I. R. Nizameev, S. A.
Katsyuba and M. Y. Balakina, Dyes and Pigments, 2018, 158, 131-141.
A. A. Kalinin, S. M. Sharipova, T. I. Burganov, A. I. Levitskaya, Y. B. Dudkina, A. R. Khamatgalimov, S.
A. Katsyuba, Y. H. Budnikova and M. Y. Balakina, Dyes and Pigments, 2018, 156, 175-184.
S. M. Sharipova, A. A. Gilmutdinova, D. B. Krivolapov, Z. R. Khisametdinova, O. N. Kataeva and A. A.
Kalinin, Chemistry of Heterocyclic Compounds, 2017, 53, 504-510.
T. I. Burganov, S. A. Katsyuba, S. M. Sharipova, A. A. Kalinin, A. Monari and X. Assfeld, Physical
Chemistry Chemical Physics, 2018, 20, 21515-21527.
T. I. Burganov, N. A. Zhukova, V. A. Mamedov, C. Bannwarth, S. Grimme and S. A. Katsyuba, Physical
Chemistry Chemical Physics, 2017, 19, 6095-6104.
M. M. Hu, Q. H. Xu, Y. X. Jiang, H. C. Mu, L. Gao, P. J. Hu, J. H. Huang and J. H. Su, Dyes and Pigments,
2018, 150, 185-192.
C. T. Chen, Y. Wei, J. S. Lin, M. Moturu, W. S. Chao, Y. T. Tao and C. H. Chien, Journal of the American
Chemical Society, 2006, 128, 10992-10993.
X. J. Yin, H. D. Sun, W. X. Zeng, Y. P. Xiang, T. Zhou, D. G. Ma and C. L. Yang, Organic Electronics,
2016, 37, 439-447.
P. F. Wang, Z. Y. Xie, O. Y. Wong, C. S. Lee, N. B. Wong, L. S. Hung and S. T. Lee, Chemical
Communications, 2002, 1404-1405.
K. R. J. Thomas, J. T. Lin, Y. T. Tao and C. H. Chuen, Journal of Materials Chemistry, 2002, 12, 3516-
3522.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
C. H. Chen, L. C. Hsu, P. Rajamalli, Y. W. Chang, F. I. Wu, C. Y. Liao, M. J. Chiu, P. Y. Chou, M. J. Huang,
L. K. Chu and C. H. Cheng, Journal of Materials Chemistry C, 2014, 2, 6183-6191.
T. H. Su, C. H. Fan, Y. H. Ou-Yang, L. C. Hsu and C. H. Cheng, Journal of Materials Chemistry C, 2013,
1, 5084-5092.
53.
54.
M. C. Bagley, Z. F. Lin and S. J. A. Pope, Tetrahedron Letters, 2009, 50, 6818-6822.
F. Lincker, D. Kreher, A. J. Attias, J. Do, E. Kim, P. Hapiot, N. Lemaitre, B. Geffroy, G. Ulrich and R.
Ziessel, Inorganic Chemistry, 2010, 49, 3991-4001.
55.
S. Achelle, J. Rodriguez-Lopez, F. Bures and F. Robin-le Guen, Dyes and Pigments, 2015, 121, 305-
311.
56.
57.
S. Achelle and F. Robin-le Guen, Tetrahedron Letters, 2013, 54, 4491-4496.
C. Hadad, S. Achelle, I. Lopez-Solera, J. C. Garcia-Martinez and J. Rodriguez-Lopez, Dyes and
Pigments, 2013, 97, 230-237.
58.
59.
F. Santoro and D. Jacquemin, Wiley Interdisciplinary Reviews-Computational Molecular Science,
2016, 6, 460-486.
A. Segalina, X. Assfeld, A. Monari and M. Pastore, Journal of Physical Chemistry C, 2019, 123, 6427-
6437.
60.
61.
C. Adamo and D. Jacquemin, Chemical Society Reviews, 2013, 42, 845-856.
D. Jacquemin, V. Wathelet, E. A. Perpete and C. Adamo, Journal of Chemical Theory and
Computation, 2009, 5, 2420-2435.

ACCEPTED MANUSCRIPT
62.
T. Burganov, S. Katsyuba, A. Zagidullin, E. Oshchepkova, V. Miluykov, A. Monari and X. Assfeld, Dyes
and Pigments, 2019, 164, 363-371.
63.
64.
M. Pastore, X. Assfeld, E. Mosconi, A. Monari and T. Etienne, Journal of Chemical Physics, 2017, 147.
T. Etienne, X. Assfeld and A. Monari, Journal of Chemical Theory and Computation, 2014, 10, 3896-
3905.
65.
T. Etienne, X. Assfeld and A. Monari, Journal of Chemical Theory and Computation, 2014, 10, 3906-
3914.
66.
67.
A. M. Brouwer, Pure and Applied Chemistry, 2011, 83, 2213-2228.
M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V.
Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov,
J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M.
Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. J. A. Montgomery, J. E. Peralta, F.
Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J.
Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M.
Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E.
Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma,
V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B.
Foresman, J. V. Ortiz, J. Cioslowski and D. J. Fox, Gaussian 09, Gaussian, Inc., revision D.01.,
Wallingford, 2014.
68.
69.
70.
71.
72.
73.
F. Weigend, Physical Chemistry Chemical Physics, 2006, 8, 1057-1065.
F. Weigend and R. Ahlrichs, Physical Chemistry Chemical Physics, 2005, 7, 3297-3305.
C. Adamo, G. E. Scuseria and V. Barone, Journal of Chemical Physics, 1999, 111, 2889-2899.
C. Adamo and V. Barone, Journal of Chemical Physics, 1999, 110, 6158-6170.
T. Yanai, D. P. Tew and N. C. Handy, Chemical Physics Letters, 2004, 393, 51-57.
T. Etienne, H. Gattuso, C. Michaux, A. Monari, X. Assfeld and E. A. Perpete, Theoretical Chemistry
Accounts, 2016, 135.
74.
75.
76.
77.
78.
79.
NANCY-EX, http://nancyex.sourceforge.net Accessed.
E. Cances, B. Mennucci and J. Tomasi, Journal of Chemical Physics, 1997, 107, 3032-3041.
J. Tomasi, B. Mennucci and R. Cammi, Chemical Reviews, 2005, 105, 2999-3093.
B. Mennucci, E. Cances and J. Tomasi, Journal of Physical Chemistry B, 1997, 101, 10506-10517.
D. Jacquemin, X. Assfeld, J. Preat and E. A. Perpete, Molecular Physics, 2007, 105, 325-331.
J. Preat, P. F. Loos, X. Assfeld, D. Jacquemin and E. A. Perpete, International Journal of Quantum
Chemistry, 2007, 107, 574-585.
80.
81.
R. Bauernschmitt and R. Ahlrichs, Chemical Physics Letters, 1996, 256, 454-464.
R. Bauernschmitt, M. Haser, O. Treutler and R. Ahlrichs, Chemical Physics Letters, 1997, 264, 573-
578.
82.
F. Furche, Journal of Chemical Physics, 2001, 114, 5982-5992.

ACCEPTED MANUSCRIPT
Highlights
•
•
•
•
•
a series of novel quinoxaline- and quinoxalinone-based chromophores is synthesized
absorption/emission of the chromophores span from the UV to the NIR
the absorption spectra are reliably simulated quantum chemically
the positions of the emission bands are also reproduced by the computations
quantum yields of emission are qualitatively predictable by empirical rules