Photophysical properties of acid-responsive triphenylamine derivatives bearing pyridine fragments: Towards white light emission

Article abstract of DOI:10.1016/j.dyepig.2017.07.043

The synthesis, thermal, electrochemical, and optical properties of a series of triphenylamine derivatives bearing pyridine fragments and their trifluoroacetate salts are described. A dramatic increase in the intramolecular charge transfer is observed upon protonation, as evidenced by a significant reduction in the HOMO-LUMO gap and a red shift of both the absorption and the emission band. White photoluminescence was obtained in solution by the controlled protonation of blue emitting pyridine derivatives, which resulted in the yellow-orange emissive acidified form. In the solid state the emission color of doped polystyrene thin films could be tuned from steel blue to lawn green when the ratio of the protonated form was increased. These compounds have potential applications in the fabrication of multi-color OLEDs based on only one material.

Full text of DOI:10.1016/j.dyepig.2017.07.043

Accepted Manuscript
Photophysical properties of acid-responsive triphenylamine derivatives bearing
pyridine fragments: Towards white light emission
Jiří Tydlitát, Sylvain Achelle, Julián Rodríguez-López, Oldřich Pytela, Tomáš Mikýsek,
Nolwenn Cabon, Françoise Robin-le Guen, David Miklík, Zdeňka Růžičková, Filip
Bureš
PII:
S0143-7208(17)31213-5
10.1016/j.dyepig.2017.07.043
DYPI 6132
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 25 May 2017
Revised Date: 14 July 2017
Accepted Date: 17 July 2017
Please cite this article as: Tydlitát Jiří, Achelle S, Rodríguez-López Juliá, Pytela Oldř, Mikýsek Tomáš,
Cabon N, Robin-le Guen Franç, Miklík D, Růžičková Zdeň, Bureš F, Photophysical properties of acid-
responsive triphenylamine derivatives bearing pyridine fragments: Towards white light emission, Dyes
and Pigments (2017), doi: 10.1016/j.dyepig.2017.07.043.
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1
ACCEPTED MANUSCRIPT
Photophysical properties of acid-responsive
triphenylamine derivatives bearing pyridine
fragments: towards white light emission
*,a
*,b
*,c
a
Jiří Tydlitát,
Sylvain Achelle,
Julián Rodríguez-López, Oldřich Pytela, Tomáš
d
b
b
a
e
Mikýsek, Nolwenn Cabon, Françoise Robin-le Guen, David Miklík, Zdeňka Růžičková,
a
and Filip Bureš
a
Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University
of Pardubice, Studentská 573, Pardubice 53210, Czech Republic. jiri.tydlitat@upce.cz
b
Institut des Sciences Chimiques de Rennes UMR CNRS 6226, IUT de Lannion, rue Edouard
Branly, BP 30219, F22302 Lannion Cedex, France. sylvain.achelle@univ-rennes1.fr
c
Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, 13071
Ciudad Real, Spain. julian.rodriguez@uclm.es
d
Department of Analytical Chemistry, Faculty of Chemical Technology, University of
Pardubice, Studentská 573, Pardubice 53210, Czech Republic.
e
Department of General and Inorganic Chemistry, University of Pardubice, Studentská 573,
Pardubice 53210, Czech Republic
TOC

2
ACCEPTED MANUSCRIPT
Abstract
The synthesis, thermal, electrochemical, and optical properties of a series of triphenylamine
derivatives bearing pyridine fragments and their trifluoroacetate salts are described. A
dramatic increase in the intramolecular charge transfer is observed upon protonation, as
evidenced by a significant reduction in the HOMO-LUMO gap and a red shift of both the
absorption and the emission band. White photoluminescence was obtained in solution by the
controlled protonation of blue emitting pyridine derivatives, which resulted in the yellow-
orange emissive acidified form. In the solid state the emission color of doped polystyrene thin
films could be tuned from steel blue to lawn green when the ratio of the protonated form was
increased. These compounds have potential applications in the fabrication of multi-color
OLEDs based on only one material.
Keywords: Triphenylamine, Pyridine, Fluorescence, White-light emission, Protonation,
Intramolecular charge transfer.
Introduction
In the past decade there has been great interest in the development of white light emitting
1
,2
systems.
The recent commercialization of White Organic Light Emitting Diodes
3
,4
(
WOLEDs), first reported by Kido, has been the subject of numerous studies. When
compared to their inorganic counterparts, all-organic light emitting molecules have
advantages such as lower cost, easy fine tuning of the solution processability, low toxicity,
2
,5–7
and sufficient flexibility for device fabrication.
White light can be obtained by mixing
three primary color emitters (red, green, and blue). Mixing two complementary color emitters
in appropriate proportions can also generate white light. White emission was defined by the
Commission Internationale d'Eclairage standard colorimetric system (CIE 1931) and it

3
ACCEPTED MANUSCRIPT
corresponds to color coordinates close to the Plankian locus around the equi-energy white
2
,8
point (x = 0.33, y = 0.33).
White light is generally obtained by the combination of independent chromophores, but a
new strategy has recently been proposed that involves the use of two different forms of the
same chromophore in equilibrium. The two forms should exhibit complementary emitting
9
–11
12–17
colors and can consist of monomer/excimer,
neutral/(de)protonated species,
Lewis
1
6
18
base/adduct or free/complexed ligand.
Nitrogen-based π-deficient heterocycles such as pyridine,
1
9–21
22–25
26,27
pyrimidine,
pyrazine,
12,28
19,29
quinazoline
or benzimidazole
can be used as the electron-withdrawing unit in push-
1
2,22,26,27,30–33
18,34–36
33,36,37
pull luminophores. Protonation,
complexation
or alkylation
of such
heterocycles enhances their electron-withdrawing character by engaging nitrogen electron
lone pairs, thus increasing the intramolecular charge transfer (ICT). This process can lead to
1
2,22,30–33
emission quenching, but in some cases red shifted emission is observed.
Recently, we
described white light emission, both in solution and in thin films, from mixtures of neutral
3
8,39
and protonated forms of methoxy-substituted pyrimidine derivatives.
The triphenylamine (TPA) fragment can be used as a moderate electron-donating unit in
push-pull luminophores. Such compounds have been used for their sensing activities versus
4
0–42
43–45
46
47–50
metal cations,
cyanide,
water or nitro aromatic explosives.
The TPA moiety has
5
1–55
been extensively used in the design of two photon excited fluorophores,
mainly for
5
6–59
bioimaging applications.
Moreover, TPA derivatives are known to exhibit aggregation-
4
6,60,61
induced emission properties
and some of these systems have been used in a range of
6
2–64
electroluminescent devices.
The aim of the work described in this paper was to study the luminescence properties – both
in solution and in thin films – of mixtures of neutral and protonated forms of seven TPA

4
ACCEPTED MANUSCRIPT
derivatives with pyridine fragments (Chart 1). The results obtained show the potential of these
materials in the fabrication of multi-color OLEDs based on only one material.
Chart 1.
Results and discussion
Synthesis
Compounds 1–3 were obtained in excellent yield by Suzuki cross coupling between pyridin-
4
-ylboronic acid and the corresponding (poly)iodotriphenylamine according to a literature
3
3
procedure (Scheme 1). The acetylenic derivatives 4–6 were synthesized by Sonogashira
cross coupling between 4-iodopyridine and the corresponding (poly)ethynyltriphenylamine.
The olefinic derivative 7 was obtained as described in the literature by Heck cross coupling
6
5
reaction of 4-bromotriphenylamine and 4-vinylpyridine. Trifluoroacetate salts 8–14, i.e., the
protonated forms of compounds 1–7, were also isolated. All new materials were characterized
1
13
by H and C NMR spectroscopy and by MALDI high-resolution mass spectrometry
(MALDI-HRMS).

5
ACCEPTED MANUSCRIPT
Scheme 1 Synthesis of compounds 1–14.
Single crystal structure
Monocrystals of compounds 1, 2, 3 and 10 suitable for X-ray crystal structure analysis were
obtained by slow evaporation of the following solvent mixtures CHCl /EtOAc, EtOAc/EtOH,
3
EtOAc/MeOH, and acetone/CHCl /pentane, respectively. The ORTEP plots shown in Fig. 1
3
confirm the proposed molecular structures of 1, 2, 3 and 10. All of these molecules adopt a
typical propeller-like arrangement of the central TPA unit. The X-ray structures of 1, 2, 3, and
10 showed a significant twist between the phenyl and pyridine rings with torsion angles of
29–51°. In this respect, the highest value was found for chromophore 1 whereas chromophore
3 showed a lower value for one of its branches, with a torsion angle of 6° enforced by
intensive π-stacking between pyridine rings in the crystal (Fig. S43, ESI). Solid state
supramolecular assemblies of the chromophores revealed a head-to-tail arrangement typical of
dipolar molecules. The X-ray data can further be used to assess the extent of the ICT by

6
ACCEPTED MANUSCRIPT
6
6–68
evaluating the aromaticity by considering the Bird index (I6)
of the terminal pyridine
ring(s). The calculated values for the pyridine rings of 1, 2 and 3, and the pyridinium ring of
0 were found to be within the range of I = 93.1–95.9 and 86.7–89.8, respectively.
1
6
Considering the value of I = 85.7 for unsubstituted pyridine, all terminal pyridine moieties
6
possess relatively high aromatic character – although it is worth noting that this can be
reduced by protonation. These findings are consistent with previous values for N,N-
6
9
di(pyridin-4-yl)pyridin-4-amine (I = 94.4–95.9).
6
Fig. 1 The molecular structures of a) chromophore 1 (ORTEP 50% probability level), b)
chromophore 2 (ORTEP 50% probability level), c) chromophore 3 (ORTEP 50% probability
level), and d) pyridinium salt 10 (ORTEP 40% probability level). Solvent molecules and
–
CF COO ions (for 10) have been omitted for clarity.
3

7
ACCEPTED MANUSCRIPT
Thermal properties
The thermal behavior of compounds 1–14 was studied by differential scanning calorimetry
DSC). Representative thermographs of unprotonated compounds 1, 5, and 6 are shown in
Fig. 2 and the melting points (T ) and the thermal decomposition temperatures (T ) are listed
(
m
d
in Table 1. Pyridine-terminated compounds 1–7 gave simple and easily interpreted DSC
curves. The measured melting points of 1–7 range from 118 to 258 °C. The decomposition
temperature was estimated to be within the range 248–310 °C. On the other hand, pyridinium
salts 8–14 exhibited more complicated thermographs with several exo/endothermic processes
that were difficult to interpret, probably due to the ionic and multipodal character of the
compounds. However, the measured melting points of 8–14 range from 115 to 202 °C and the
decomposition temperatures were estimated to be within the range 190–220 °C. In general,
the pyridinium salts 8–14 had lower melting points and lower thermal robustness. For further
discussion on the thermal stability of compounds 1–14 see the ESI.
Fig. 2 Representative DSC thermographs of unprotonated compounds 1, 5 and 6 obtained
with a scanning rate of 3 °C/min in the range 25–400 °C.

8
ACCEPTED MANUSCRIPT
Table 1 Thermal and electrochemical properties of chromophores 1–14.
a
b
(ox1)c,d
(red1)c,e
c
f
f
Tm
Td
E1/2
(V)
1.07
E1/2
(V)
–2.15
∆E
(V)
3.22
EHOMO
(eV)
ELUMO
(eV)
Compd
(
°C)
(°C)
1
2
3
4
5
6
7
8
9
143
147
258
196
118
235
/
115
133
196
141
/
/
–5.42
–5.44
–5.46
–5.44
–5.47
–5.54
–5.41
–5.47
–5.48
–5.49
–5.42
–5.46
–5.50
–5.31
–2.20
–2.25
–2.28
–2.40
–2.49
–2.50
–2.54
–3.14
–3.16
–3.18
–3.28
–3.30
–3.33
–3.35
≈248
/
1.09
1.11
1.09
1.12
1.19
1.06
1.12
1.13
1.14
1.07
1.11
1.15
0.96
–2.10
–2.07
–1.96
–1.86
–1.85
–1.82
–1.21
–1.19
–1.17
–1.07
–1.05
–1.02
–1.00
3.19
3.17
3.05
2.98
3.04
2.87
2.33
2.32
2.32
2.14
2.16
2.17
1.96
295
310
256
286
200
220
207
190
192
199
201
1
1
1
1
1
0
1
2
3
4
/
189
a
T = melting point (the point of intersection of a baseline before the thermal effect with a
m
b
c
(ox1)
(red1)
tangent). T = thermal decomposition (pyrolysis in a N atmosphere). E
and E1/2
are half-wave potentials of the first oxidation and reduction, respectively; all potentials are
d
2
1/2
(ox1)
(red1)
d
e
given vs SCE (Saturated Calomel Electrode); ∆E = E
drop– polarography E
– E1/2
. Pt disk – RDV Hg
1
/2
f
(ox1/red1)
= E1/2
+ 4.35.
HOMO/LUMO
Electrochemistry
Electrochemical measurements on chromophores 1–14 were carried out in DMF containing
.1 M Bu NPF in a three electrode cell by cyclic voltammetry (CV), rotating disc
0
4
6
voltammetry (RDV), and polarography.
(ox1)
(red1)
The measured half-wave potentials of the first oxidation and reduction (E1/2
and E1/2
)
of chromophores 1–14, measured by RDV and polarography experiments respectively, were
found within the ranges 0.96 to 1.19 and –1.00 to –2.15 V vs SCE, respectively. The first
reduction and oxidation are followed by subsequent oxidations and reductions, and they are
clearly a function of the peripheral acceptor and the π-linker (Table 1). Whereas the first one
electron oxidation can be attributed to the central TPA donor, the first reduction is mostly
localized on the terminal pyridine/pyridinium ring and the appropriate π-linker. The LUMO
and HOMO energy levels (easily calculated from the first oxidation and reduction potentials
(red1)/(ox1)
as –ELUMO/LUMO = E1/2
+ 4.35) of chromophores 1–14 can be discussed from two

9
ACCEPTED MANUSCRIPT
points of view involving the branching and the nature of the π-linker. On changing from
linear across quadrupodal to tripodal derivatives, a general decrease in the LUMO energies is
observed for both pyridine and pyridinium derivatives. The most obvious difference was seen
for acetylenic pyridine derivatives 4 and 6 with ELUMO = –2.40 and –2.50 eV, respectively.
The HOMO energy levels showed similar trends. Within the series of linear derivatives 1, 4,
and 7, which incorporate various π-linkers, ELUMO decreases from –2.20 eV for chromophore
1
to –2.54 eV for olefinic derivative 7. Linear pyridinium derivatives 8, 11, and 14 generally
possess lower energies than the corresponding pyridine-terminated derivatives 1, 4, and 7 due
to higher electron-withdrawing power of the pyridinium over pyridine moieties. On the other
hand, EHOMO increases within the same series of compounds with the highest values of –5.41
and –5.31 eV obtained for pyridine 7 and pyridinium 14, both of which are olefinic
derivatives. In any case, the best way to evaluate the impact of the structural features on the
electrochemical properties is through the HOMO-LUMO gap ∆E. The parallel trends outlined
above for the HOMO and LUMO energies imply that branching did not affect the ∆E absolute
values but rather shifts in both HOMO and LUMO levels to lower values occur. This situation
7
0
is consistent with our recent general observation on branching. The effect of the π-linker can
be demonstrated in series 1 (none), 4 (acetylenic) and 7 (olefinic) or 8 (none), 11 (acetylenic)
and 14 (olefinic). In both series there is a steady decrease in ∆E caused mostly by variation of
the ELUMO (see Fig. 3). This energy level diagram further illustrates differences between
pyridine- and pyridinium-terminated chromophores. The latter showed decreases in the
HOMO-LUMO gap by 0.89–0.91 eV. The smallest HOMO-LUMO gap of 1.96 eV was
measured for linear pyridinium chromophore 14. When comparing these results with those of
7
1
previous tripodal TPA derivatives bearing 4-cyanophenyl acceptors, pyridine analogs
showed higher ∆E values by 0.16–0.22 eV, whereas pyridinium derivatives have ∆E values
that are significantly narrowed by 0.69–0.75 eV.

1
0
ACCEPTED MANUSCRIPT
Fig. 3 Energy level diagram for linear chromophores 1, 4, 7, 8, 11, and 14.
DFT calculations
The spatial and electronic properties of chromophores 1–14 were investigated using the
7
2
Gaussian W09 package at the DFT level. The initial geometries of molecules 1–14 were
estimated and optimized using the DFT B3LYP/6-31G(d) and DFT B3LYP/6-311G(2d,p)
methods. The HOMO and LUMO energies, their differences, and the ground state dipole
moments were calculated at the DFT B3LYP/6-311++G(2d,p) level and are summarized in
Table 2.

1
1
ACCEPTED MANUSCRIPT
Table 2 DFT calculated properties of chromophores 1–14.
a
a
Symmetry
group
C2
EHOMO
(eV)
ELUMO
(eV)
∆E
µ (D)
Compd
(eV)
3.88
3.77
3.77
3.51
3.36
3.34
3.30
2.54
2.45
2.82
2.12
2.12
2.37
2.22
1
2
3
4
5
6
7
8
9
–5.44
–5.57
–5.69
–5.45
–5.58
–5.68
–5.36
–8.32
–1.57
–1.80
–1.92
–1.94
–2.22
–2.34
–2.05
–5.78
–8.01
–9.52
–5.88
–7.66
–8.94
–5.75
3.8
3.6
0.0
5.0
4.4
C2
D3
C2
C2
D3
C1
C2
C2
D3
C2
C2
C3
0.0
4.8
13.9
11.6
0.0
17.4
14.4
0.1
–10.46
–12.34
–8.01
10
11
12
13
14
–9.78
–11.31
–7.97
C1
16.2
a
Calculated at the DFT B3LYP/6-311++G(2d,p) level.
The calculated energies of the HOMO of pyridine derivatives 1–7 range from –5.69 to –
5
.36 eV and the LUMO energies from –2.34 to –1.57 eV and these values reflect structural
differences of the individual chromophores. In contrast to the electrochemical measurements,
the calculated energies of 8–14 are affected by anion exclusion and by calculation in vacuum.
Hence, generally higher HOMO and LUMO values of –7.97 to –12.34 eV and –5.75 to –
9
.52 eV were obtained. However, the calculated ∆E values correlate reasonably well with the
experimental values obtained by electrochemical measurements (Fig. S44, ESI). Comparison
with the electrochemical data shows similar trends in the calculated HOMO and LUMO
energies, i.e., branching, π-linker nature and electron-withdrawing power of pyridine and
pyridinium moieties affect the ∆E most significantly. The calculated HOMO-LUMO gaps,
which were within the range 3.88–2.12 eV, correlate well with the electrochemical data, with
differences between 0.02 and 0.66 eV. The HOMO and LUMO localizations in representative
molecules (for a complete listing see the ESI) are shown in Fig. 4. As expected, the HOMO is
localized on the central TPA donor, whereas the LUMO is predominantly spread over the

1
2
ACCEPTED MANUSCRIPT
pyridine or pyridinium acceptors. In quadrupolar and tripodal molecules, the LUMO occupies
mostly one or two branches and the third one is occupied by the LUMO+1. This is a common
7
0,71
feature of multipodal push-pull chromophores.
The calculated ground state dipole
moments strictly obey the molecular structure of the particular chromophores. While tripodal
molecules 3, 6, and 10 with D3 symmetry have almost zero dipole moment, the remaining
ones that fall within the C1, C2 and C3 symmetry groups had dipole moments within the
range 0.1–17.4 D.
HOMO/LUMO (1)
HOMO/LUMO (2)
HOMO/LUMO (3)
HOMO/LUMO (8)
HOMO/LUMO (9)
HOMO/LUMO (10)
Fig. 4 Representative HOMO (red) and LUMO (blue) localizations in 1–3 and 8–10.
UV-vis and fluorescence spectroscopy
The UV-vis and photoluminescence (PL) spectroscopic data for compounds 1–7, measured in
chloroform, are presented in Table 3. The analyses were carried out using low concentration
–
5
solutions ((1.0–2.0) × 10 M). Under these conditions, self-absorption effects were not
observed. As representative examples, the spectra of derivatives 4–6 are shown in Fig. 5.

1
3
ACCEPTED MANUSCRIPT
Table 3 UV-vis and photoluminescence (PL) data in CHCl solution.
3
b
λabs
ε
λem
Stokes shift Brightness
Compd
–
1
–1
a
–1
–1
–1
(nm)
(mM cm ) (nm) ΦF
(cm )
(mM cm )
1
2
3
4
5
6
7
349
363
361
25.6
26.5
55.4
444 0.50
431 0.54
429 0.50
456 0.78
442 0.74
439 0.63
485 0.45
6130
4346
4391
5097
3347
3347
5288
12.8
14.3
27.7
24.1
32.7
48.2
12.6
292, 370
258, 382
271, 382
296, 386
14.6, 31.0
27.4, 44.2
43.0, 76.6
19.6, 28.0
a
Fluorescence quantum yield (±10%) determined relative to 9,10-
bis(phenylethynyl)anthracene in cyclohexane (Φ = 1.00) as standard.
F
b
Calculated as the product of ε and ΦF.
Fig. 5 Normalized absorption (dashed lines) and emission spectra (solid lines) of compounds
4
(green), 5 (blue), and 6 (red) in CHCl solution.
3
All of the compounds exhibited intense blue luminescence with fluorescence quantum
yields (Φ ) up to 78%. A bathochromic shift of the charge transfer absorption band was
F
observed on going from a mono-substituted (dipolar) to a di- or tri-substituted (quadrupolar or
octupolar) TPA, while the emission band was hypsochromically shifted. This effect leads to a
5
1,73
decreased Stokes shift and is consistent with results obtained for similar TPA derivatives.
For octupolar TPA derivatives, a dramatic increase in the molar extinction coefficient and
brightness was found. This feature is ascribed to the degeneracy of the S1 state of these
7
3
compounds, which alters the electronic levels of the TPA core through π-conjugation. When

1
4
ACCEPTED MANUSCRIPT
comparing the three monosubstituted TPA derivatives (compounds 1, 4, and 7), the
absorption and emission maxima increase in the order λmax (1) < λmax (4) < λmax (7), thus
indicating an enhanced ICT when a π-linker is placed between the TPA fragment and the
pyridine moiety, in accordance with electrochemical measurements. This observation is also
5
1
consistent with results reported for related compounds.
Solvatochromic behavior
The solvatochromic shifts of the emission bands can be used to evaluate the ICT upon
excitation into push-pull compounds. With such compounds a broad, structureless red-shifted
emission is observed on increasing the solvent polarity along with a successive decrease of
the fluorescence intensity. This positive solvatochromic behavior, which results from the
stabilization of a highly polar emitting state by polar solvents, has been fully documented for
2
2,26,27,52,56–59
donor-acceptor fluorophores.
Thus, the emission spectra of the studied
compounds were measured in seven aprotic solvents of different polarity. The results of these
investigations are summarized in Table 4. For all compounds, a bathochromic shift of the
emission band was observed as the solvent polarity was increased, as predicted by the
7
4,75
Dimroth–Reichardt polarity parameters (E (30)).
As examples, the changes in the
T
emission spectra of 4 and in the color of a solution of 7 under UV irradiation in various
solvents are shown in Figs. 6 and 7, respectively. Good linearity was observed when the
emission maxima were plotted vs E (30) in all cases (Fig. 8). The slopes of the corresponding
T
regression lines are good indicators of the intensity of the ICT. Concerning monosubstituted
dipolar TPA derivatives, in accordance with the observations on the position of absorption
and emission maxima, the slope increased when acetylenic or olefinic linkers were added (4
and 7 vs 1). Surprisingly, the slope is higher for 4 than for 7. Increasing the substitution of the
TPA core decreased the value of the slope.

1
5
ACCEPTED MANUSCRIPT
Table 4 Emission solvatochromism of TPA derivatives 1–7 in various aprotic solvents.
Heptane Toluene
THF
37.4
CH Cl
40.7
Acetone
42.2
MeCN
45.6
DMSO
45.1
2
2
a
a
a
a
a
a
a
3
0.9
33.9
Compd λmax (nm) λmax (nm) λmax (nm) λmax (nm) λmax (nm) λmax (nm) λmax (nm)
1
2
3
4
5
6
7
389
394
390
398
404
404
424
412
407
408
421
419
416
448
433
428
427
450
435
437
475
451
442
441
473
453
451
498
458
449
449
481
466
465
472
467
460
497
480
477
515
472
463
461
506
493
483
521
500
a
–1
E (30), Dimroth–Reichardt polarity parameter in kcal mol .
T
Fig. 6 Normalized emission spectra of 4 in different aprotic solvents.
Fig. 7 Fluorescence color changes experienced by 7 in various solvents (from left to right:
heptane, toluene, THF, CH Cl , acetone, MeCN, DMSO). Picture was taken in the dark upon
2
2
irradiation with a hand-held UV lamp (λem = 366 nm).

1
6
ACCEPTED MANUSCRIPT
Fig. 8 Emission maxima (λ ) as a function of the Dimroth–Reichardt polarity parameter
em
ET(30) for TPA derivatives 1–7.
Protonation study
1
NMR studies. Protonation of the pyridine-terminated chromophore 4 was studied by H NMR
spectroscopy (Fig. 9). The gradual addition of trifluoroacetic acid (TFA) to a CDCl solution
3
of 4 resulted in the shift of particular signals, especially those belonging to the pyridine ring.
1
A
B
C
D
Initially, the H NMR spectrum of 4 showed two sets of doublets (H /H and H /H )
corresponding to the pyridine and the 1,4-phenylene units, respectively, as well as three
E
F
G
additional groups of signals (H /H /H ) for the additional two phenyl rings.
A
B
Upon addition of TFA, the pyridine signals H /H were progressively shifted downfield. As
expected, the positions of the remaining signals were affected to a lesser extent by
protonation. The absence of two sets of signals for mixtures of 4 and 11 (e.g., green, violet,
B
and yellow spectra) indicates a fast proton exchange in solution. Protons H showed the
largest difference in the chemical shifts (7.33 ppm in 4 vs 7.71 ppm in 11). The coupling

1
7
ACCEPTED MANUSCRIPT
3
A
B
constant J(H ,H ) also increased upon protonation (5.3 Hz in 4 vs 6.0 Hz in 11). The upper-
most red spectrum corresponds to a 1:1 mixture of 4 and TFA, and is in full accordance with
the spectrum obtained for the pyridinium salt 11 (see the Experimental section).
1
Fig. 9 H NMR protonation study on chromophore 4 by gradual addition of TFA. The blue
trace corresponds to the pyridine derivative 4 while the red trace corresponds to the
pyridinium derivative 11.
Photophysical properties in solution. Photophysical measurements were also performed in
–
2
acid solution (10 M TFA in CDCl ) for compounds 1–7. The results are summarized in
3
Table 5. As expected, a bathochromic shift in the absorption and emission bands was
observed upon protonation. In general, this shift was accompanied by a decrease in both the

1
8
ACCEPTED MANUSCRIPT
fluorescence quantum yield and brightness, although these values remained relatively high for
octupolar chromophores 3 and 6. An emission solvatochromic study was also performed for
compound 8 (Fig. 10). In this case, it is worth noting that the emission was almost totally
quenched for the more polar solvents (acetone, MeCN and DMSO). The slope of the
regression lines of the emission maxima vs polarity parameters increased dramatically after
–1
–1
acidification of the solvent (Fig. 10B, 9.70 nm.mol.kJ vs 5.60 nm.mol.kJ ) and this is
consistent with a significant enhancement of the ICT into the fluorophore after protonation.
–
2
Table 5 UV/vis and PL data in acid solution (10 M TFA in CHCl ).
3
b
λabs
ε
λem
Stokes shift Brightness
Compd
–
1
–1
a
F
–1
–1
–1
(nm) (mM cm ) (nm) Φ
(cm )
(mM cm )
8
9
416
28.9
35.6
53.4
31.0
42.3
60.7
27.5
584 0.15
540 0.42
521 0.48
623 0.05
594 0.18
579 0.31
612 0.24
6915
4737
4787
6220
5288
5353
5073
4.3
14.9
25.6
1.55
7.6
18.8
6.6
430
417
449
452
442
467
10
11
12
13
14
a
Fluorescence quantum yield (±10%) determined relative to 9,10-
bis(phenylethynyl)anthracene in cyclohexane (Φ = 1.00) as standard.
F
b
Calculated as the product of ε and ΦF.
Fig. 10 A) Normalized emission spectra of 8 in different aprotic solvents. B) Emission
maxima (λ ) as a function of the Dimroth–Reichardt polarity parameters.
em

1
9
ACCEPTED MANUSCRIPT
For all of the TPA chromophores, the effect of protonation in chloroform solution was
studied by titration with TFA. As an example, the changes observed in the UV-vis and
emission spectra of 7 upon the addition of acid are illustrated in Figs. 11 and 12, respectively
(Fig. S51–S61 for the spectra of compounds 1–6, ESI). The absorption spectra showed the
progressive attenuation of the charge transfer absorption band for the neutral compounds on
increasing the concentration of acid, whereas a new red-shifted band corresponding to the
protonated species appeared. Isosbestic points were observed for TPA derivatives 1, 4, and 7,
which bear only one pyridine ring. This is not the case for the other derivatives due to the
coexistence of diprotonated or triprotonated species. Surprisingly, compounds with acetylenic
linkers (4–6) required a significantly higher TFA concentration before changes in their
absorption spectra were observed. The same trends were observed in the emission properties,
i.e., the addition of TFA led to a decrease in the emission band intensity and a new red-shifted
band appeared with an isoemissive point for monosubstituted TPA derivatives. The intensity
of both bands became similar after the addition of 0.8 equiv of TFA to a solution of 7 in
CHCl (λ = 410 nm) (Fig. 12). The coexistence of both neutral and protonated forms led
3
exc
this solution to emit white light under UV irradiation, while under the same conditions, the
nonprotonated and fully protonated solutions appeared blue and orange, respectively (Fig.
1
3). Similar behavior was observed for compounds 1–6 and chromaticity coordinates close to
those of pure white light (0.33, 0.33) could be obtained in all cases (Table 6). It is noteworthy
that in the case of compound 4 the addition of TFA resulted in a dramatic decrease in the
emission intensity. Thus, low emission intensity was observed when both bands reached the
same height (Fig. S59, ESI).

2
0
ACCEPTED MANUSCRIPT
–5
Fig. 11 Changes in the absorption spectra of a CHCl solution of 7 (c = 1.86 × 10 M) upon
3
addition of TFA (0.1–5.0 equiv).
–
5
Fig. 12 Changes in the emission spectra of a CHCl solution of 7 (c = 1.86 × 10 M) upon
3
addition of TFA (0.1–5.0 equiv). λexc = 410 nm.
–
5
Fig. 13 Changes in the color of a CHCl solution of 7 (c = 1.86 × 10 M) after the addition of
3
0
.8 equiv (middle) and 5 equiv of TFA (right). Photographs were taken in the dark upon
irradiation with a hand-held UV lamp (λ = 366 nm).
em

2
1
ACCEPTED MANUSCRIPT
Table 6 CIE coordinates for TPA derivatives in CHCl solution
3
–
5
(
c = (1.0–2.0) × 10 M).
Chromaticity coordinates (x,y)
Mixture of neutral
and protonated forms
Compd Neutral form Protonated form
a
1
2
3
4
5
6
7
(0.17, 0.12)
(0.16, 0.08)
(0.16, 0.07)
(0.15, 0.16)
(0.15, 0.10)
(0.15, 0.09)
(0.17, 0.29)
(0.45, 0.47)
(0.38, 0.56)
(0.35, 0.51)
(0.45, 0.39)
(0.45, 0.40)
(0.51, 0.45)
(0.33, 0.32)
b
(0.33, 0.35)
c
(0.30, 0.34)
d
(0.34, 0.30)
e
(0.35, 0.31)
f
(0.34, 0.30)
g
(0.51, 0.49)
(0.32, 0.36)
a
b
0
.8 equiv of TFA, λ = 380 nm. 4.0 equiv of TFA, λ = 390
exc
exc
c
d
nm. 10.0 equiv of TFA, λ = 380 nm. 400 equiv of TFA, λ
exc
exc
e
f
=
390 nm. 250 equiv of TFA, λ = 250 nm. 160 equiv of TFA,
exc
g
λexc = 390 nm. 0.6 equiv of TFA, λexc = 410 nm.
Photophysical properties in thin film. According to the protocol that some of us described
3
8
previously for a pyrimidine fluorophore, thin films of polystyrene doped with 1 wt% of
compounds 1 and 7 were prepared using different ratios of neutral and protonated forms. The
emission spectra of the samples obtained for 1 are shown in Fig. 14. Although the films
remained luminescent, both bands experienced a significant blue shift when compared to the
CHCl solution. In this case, the chromaticity coordinates were far from those of pure white
3
light regardless of the neutral (1)/protonated (8) form ratio (Table 7). When compound 7 was
used, it was not possible to obtain white luminescence either, although the chromaticity
coordinates were closest to those of white light when 0.6 equiv of TFA were employed (0.25,
0
.36) (Table S4, ESI). Nevertheless, with this fluorophore the emission color of the thin film
could be tuned from steel blue to lawn green through cyan when the ratio of the protonated
form was increased (Fig. 15).

2
2
ACCEPTED MANUSCRIPT
Fig. 14 Emission spectra of thin films of polystyrene doped with 1% wt of different ratios of 1
and 8, λexc = 380 nm.
Table 7 CIE coordinates of thin films of polystyrene doped with
1
%wt of various ratios of 1/8, λexc = 380 nm.
1
/8 ratio
Chromaticity coordinates (x,y)
1
2
1
1
0
/0
/1
/1
/2
/1
(0.16, 0.13)
(0.16, 0.27)
(0.18, 0.24)
(0.17, 0.38)
(0.17, 0.41)
Fig. 15 Colors of polystyrene thin films doped with 7 (1 wt%) in the
absence and the presence of 0.4, 0.6, and 5 equiv of TFA (from left to right). Photographs
were taken in the dark upon irradiation with a hand-held UV lamp (λem = 366 nm).

2
3
ACCEPTED MANUSCRIPT
Conclusions
In summary, the thermal, electrochemical, and optical properties of several TPA push-pull
chromophores were studied. Both the influence of branching (dipolar, quadrupolar and
tripodal structures) and the nature of the π-linker were thoroughly considered. The materials
could be easily protonated with TFA at the nitrogen atom of the pyridine ring and the
corresponding trifluoroacetate salts were isolated and characterized. Due to the higher
electron-withdrawing character of the pyridinium ring when compared to the pyridine ring,
the protonation of these chromophores resulted in an enhanced ICT into the molecule. As a
consequence, the pyridinium salts exhibited a red-shifted emission band. The controlled
protonation of the blue emitting pyridine derivatives led to white photoluminescence by
formation of a yellow/orange emissive pyridinium form. In solid state, multi-color
photoluminescence of doped polystyrene thin films was also achieved by tuning the ratio of
the pyridine/pyridinium forms. This phenomenon opens up the opportunity of exploiting these
materials for the fabrication multi-color OLEDs after suitable design of the molecules. The
electroluminescence properties of these chromophores are currently under investigation.
Experimental section
General
Details concerning material and methods are provided in the ESI. Synthesis and full
spectroscopic characterization of previously known target chromophores 1, 3, 6, and 7 is
given in the ESI.
General procedure for Suzuki–Miyaura cross-coupling (chromophores 1–3)
The appropriate mono-, di- or tri-iodo TPA derivative (300 mg) and pyridin-4-ylboronic acid
were dissolved in a mixture of dioxane/H O (25 mL, 4/1). Ar was bubbled through the
2

2
4
ACCEPTED MANUSCRIPT
mixture for 10 min and [PdCl (PPh ) ], Na CO and PPh were added. The reaction mixture
2
3 2
2
3
3
was stirred at 90 °C for 12 h. The cooled reaction mixture was diluted with H O (50 mL) and
2
extracted with CH Cl (2 × 50 mL). The combined organic extracts were then washed with
2
2
brine and dried (Na SO ). Finally, the solvents were evaporated under vacuum and the crude
2
4
product was purified by column chromatography (SiO , appropriate eluent).
2
Chromophore 2. The title compound was synthesized from 4,4'-diiodotriphenylamine (300
mg, 0.604 mmol), pyridin-4-ylboronic acid (163 mg, 1.328 mmol), [PdCl (PPh ) ] (16.95 mg,
2
3 2
0
.024 mmol), Na CO (128 mg, 1.207 mmol) and PPh (6.33 mg, 0.024 mmol) following the
2 3 3
general procedure for Suzuki–Miyaura cross-coupling. Orange solid. Yield: 219 mg (91%).
1
R : 0.25 (SiO , EtOAc/MeOH 10/1). Mp: 147 °C. H NMR (500 MHz, CDCl ):
δ (ppm) 7.11
f
2
3
3
3
(
t, 1H, J = 7.5 Hz, CH ), 7.16–7.19 (m, 6H, CH ), 7.31 (t, 2H, J = 7.5 Hz, CH ), 7.45 (d,
Ar Ar Ar
3
3
3
13
4
H, J = 5.5 Hz, CH ), 7.53 (d, 4H, J = 9.0 Hz, CH ), 8.60 (d, 4H, J = 5.5 Hz, CH ). C
Py Ar Py
NMR (125 MHz, CDCl3):
δ
(ppm) 121.0, 124.0, 124.4, 125.6, 127.9, 129.8, 132.1, 146.9,
+
1
47.5, 148.4, 150.4. HR-MALDI-MS (DHB): calcd for C H N (M ) 399.1730, found
2
8
21
3
3
99.1737.
General procedure for Sonogashira cross-coupling (chromophores 4–6)
The appropriate mono-, di- or tri-acetylene TPA derivative (200 mg) and 4-iodopyridine were
dissolved in a mixture of dioxane/piperidine (25 mL, 4/1). Ar was bubbled through the
mixture for 10 min and [Pd(PPh ) ] and CuI were added. The reaction mixture was stirred at
3
4
9
0 °C for 12 h. The cooled reaction mixture was diluted with H O (50 mL) and extracted with
2
CH Cl (2 × 50 mL). The combined organic extracts were then washed with saturated NH Cl
2
2
4
solution, brine, and dried. Finally, the solvents were evaporated under vacuum and the crude
product was purified by column chromatography (SiO , appropriate eluent).
2
Chromophore 4. The title compound was synthesized from 4-ethynyltriphenylamine (200
mg, 0.743 mmol), 4-iodopyridine (167 mg, 0.817 mmol), [Pd(PPh ) ] (17.16 mg, 0.015
3
4

2
5
ACCEPTED MANUSCRIPT
mmol) and CuI (2.83 mg, 0.015 mmol) following the general procedure for Sonogashira
cross-coupling. Yellow solid. Yield: 231 mg (90%). R : 0.6 (SiO , CHCl /EtOAc 1/1). Mp:
f
2
3
1
3
1
2
96–197 °C. H NMR (500 MHz, CDCl ):
δ
(ppm) 7.00 (d, 2H, J = 8.5 Hz, CH ), 7.08 (t,
3
Ar
3
3
3
H, J = 7.5 Hz, CH ), 7.12 (d, 4H, J = 7.5 Hz, CH ), 7.28 (t, 4H, J = 7.5 Hz, CH ), 7.33
Ar
Ar
Ar
3
3
3
(
d, 2H, J = 5.5 Hz, CH ), 7.37 (d, 2H, J = 8.5 Hz, CH ), 8.56 (d, 2H, J = 5.5 Hz, CH ).
Py
Ar
Py
1
3
C NMR (125 MHz, CDCl3):
δ
(ppm) 86.2, 94.9, 114.4, 121.8, 124.1, 125.4, 125.5, 129.7,
+
1
32.0, 133.1, 147.1, 148.9, 149.9. HR-MALDI-MS (DHB): calcd for C H N (M )
2
5
18
2
3
46.1465, found 346.1473.
Chromophore 5. The title compound was synthesized from 4,4'-diethynyltriphenylamine
200 mg, 0.682 mmol), 4-iodopyridine (307 mg, 1.5 mmol), [Pd(PPh ) ] (31.51 mg, 0.027
(
3
4
mmol) and CuI (5.19 mg, 0.027 mmol) following the general procedure for Sonogashira
cross-coupling. Yellow solid. Yield: 265 mg (87%). R : 0.6 (SiO , EtOAc/MeOH 10/1). Mp:
f
2
1
3
1
3
18 °C. H NMR (500 MHz, CDCl ):
δ
(ppm) 7.05 (d, 4H, J = 8.5 Hz, CH ), 7.12–7.15 (m,
3
Ar
3
3
H, CH ), 7.30–7.31 (m, 2H, CH ), 7.34 (d, 4H, J = 6.0 Hz, CH ), 7.41 (d, 4H, J = 8.5
Ar
Ar
Py
3
13
Hz, CH ), 8.56 (d, 4H, J = 6.0 Hz, CH ). C NMR (125 MHz, CDCl ):
δ (ppm) 86.6, 94.3,
Ar
Py
3
1
16.0, 123.3, 124.9, 125.6, 126.1, 129.9, 131.8, 133.2, 146.4, 148.0, 149.9. HR-MALDI-MS
+
(
DHB): calcd for C H N (M ) 447.1730, found 447.1739.
3
2
21
3
General procedure for the synthesis of pyridinium salts
The appropriate chromophore 1–7 (100 mg) was dissolved in chloroform (2 mL) and TFA (50
µl) was added dropwise. The solution was cooled to –10 °C and the pyridinium salt was
precipitated by gradual addition of cold pentane. The solid was collected by filtration and
washed several times with pentane.
Chromophore 8. The title compound was synthesized from 1 (100 mg, 0.31 mmol) following
the general procedure for pyridinium salts. Yellow solid. Yield: 112 mg (83%). Mp: 115 °C.
1
3
H NMR (500 MHz, CDCl3):
δ
(ppm) 7.11 (d, 2H, J = 9.0 Hz, CH ), 7.15–7.18 (m, 6H,
Ar

2
6
ACCEPTED MANUSCRIPT
3
3
CH ), 7.33–7.36 (m, 4H, CH ), 7.60 (d, 2H, J = 9.0 Hz, CH ), 7.88 (d, 2H, J = 6.5 Hz,
Ar
Ar
Ar
3
13
1
CH ), 8.72 (d, 2H, J = 6.5 Hz, CH ). C NMR (125 MHz, CDCl ):
δ (ppm) 116.9 (q, J
CF
Py
Py
3
=
290 Hz), 121.2, 122.1, 125.2, 125.9, 126.2, 128.7, 130.0, 142.2, 146.4, 151.7, 155.5, 163.0
2
+
(
q, J = 38 Hz). HR-MALDI-MS (no matrix): calcd for C H N [(M – C F O H) ]
CF 23 18 2 2 3 2
3
22.1465, found 322.1469.
Chromophore 9. The title compound was synthesized from 2 (100 mg, 0.25 mmol) following
the general procedure for pyridinium salts. Orange solid. Yield: 139 mg (89%). Mp: 133 °C.
1
3
H NMR (500 MHz, CDCl3):
δ
(ppm) 7.21 (d, 2H, J = 7.5 Hz, CH ), 7.26–7.29 (m, 5H,
Ar
3
3
3
CH ), 7.42 (t, 2H, J = 7.5 Hz, CH ), 7.68 (d, 4H, J = 9.0 Hz, CH ), 7.92 (d, 4H, J = 6.5
Ar
Ar
Ar
3
13
Hz, CH ), 8.80 (d, 4H, J = 6.5 Hz, CH ), 11.09 (br s, 2H, NH). C NMR (125 MHz,
Py
Py
CDCl3);
δ
(ppm) 122.7, 124.0, 126.4, 126.9, 128.9, 129.0, 130.4, 142.9, 145.7, 150.1, 154.9,
2
+
1
62.9 (q, J = 38 Hz). HR-MALDI-MS (no matrix): calcd for C H N [(M – C F O H ) ]
CF
28 21
3
4
6
4
2
3
99.1730, found 399.1738.
Chromophore 10. The title compound was synthesized from 3 (100 mg, 0.21 mmol)
following the general procedure for pyridinium salts. Orange solid. Yield: 160 mg (93%). Mp:
1
3
1
96 °C. H NMR (500 MHz, CDCl ):
δ
(ppm) 2.85 (br s, 3H, NH), 7.37 (d, 6H, J = 8.5 Hz,
3
3
3
3
CH ), 7.75 (d, 6H, J = 8.5 Hz, CH ), 7.94 (d, 6H, J = 6.0 Hz, CH ), 8.85 (d, 6H, J = 6.0
Ar
Ar
Py
1
3
Hz, CH ). C NMR (125 MHz, CDCl ):
δ
(ppm) 122.1, 125.1, 128.9, 132.0, 146.9, 148.6,
Py
3
+
1
4
51.0. HR-MALDI-MS (no matrix): calcd for C H N [(M – C F O H ) ] 476.1995, found
33
24
4
6
9
6
3
76.2003.
Chromophore 11. The title compound was synthesized from 4 (100 mg, 0.29 mmol)
following the general procedure for pyridinium salts. Yellow solid. Yield: 117 mg (88%). Mp:
1
3
1
6
6
41 °C. H NMR (500 MHz, CDCl ):
δ
(ppm) 6.99 (d, 2H, J = 8.5 Hz, CH ), 7.12–7.15 (m,
3
Ar
3
3
3
H, CH ), 7.32 (t, 4H, J = 7.5 Hz, CH ), 7.40 (d, 2H, J = 8.5 Hz, CH ), 7.71 (d, 2H, J =
Ar
Ar
Ar
3
13
.0 Hz, CH ), 8.70 (d, 2H, J = 6.0, CH ), 10.59 (br s, 1H, NH). C NMR (125 MHz
Py
Py

2
7
ACCEPTED MANUSCRIPT
1
CDCl3):
δ
(ppm) 85.7, 104.0, 111.9, 116.6 (q, J = 288 Hz), 120.7, 124.9, 126.1, 127.5,
CF
2
1
29.9, 133.9, 140.1, 142.7, 146.5, 150.4, 162.7 (q, JCF = 38 Hz). HR-MALDI-MS (DHB):
+
calcd for C H N [(M –C F O H) ] 346.1465, found 346.1468.
2
5
18
2
2
3
2
Chromophore 12. The title compound was synthesized from 5 (100 mg, 0.22 mmol)
following the general procedure for pyridinium salts. Yellow solid. Yield 141 mg (95%). Mp:
1
1
92 °C (decomposition). H NMR (500 MHz, CDCl ):
δ
(ppm) 3.82 (br s, 2H, NH), 7.10 (d,
3
3
3
4
H, J = 8.5 Hz, CH ), 7.16 (d, 2H, J = 8.0 Hz, CH ), 7.21–7.23 (m, 1H, CH ), 7.38 (t, 2H,
Ar Ar Ar
3
3
3
J = 8.0 Hz, CH ), 7.48 (d, 4H, J = 8.5 Hz, CH ), 7.72 (d, 4H, J = 6.0 Hz, CH ), 8.73 (d,
Ar
Ar
Py
3
13
4
H, J = 6.0 Hz, CH ). C NMR (125 MHz, CDCl ):
δ
(ppm) 85.9, 102.5, 114.5, 116.4 (q,
Py
3
1
JCF = 288 Hz), 123.2, 126.1, 126.8, 127.7, 130.3, 134.1, 139.6, 143.0, 145.8, 149.1, 162.4 (q,
2
+
JCF = 38 Hz). HR-MALDI-MS (DHB): calcd for C H N [(M – C F O H ) ] 447.1730,
32
21
3
4
6
4
2
found 447.1735.
Chromophore 13. The title compound was synthesized from 6 (100 mg, 0.18 mmol)
following the general procedure for pyridinium salts. Orange solid. Yield 152 mg (95%). Mp:
1
3
1
99 °C (decomposition). H NMR (500 MHz, CDCl ):
δ
(ppm) 7.17 (d, 6H, J = 8.5 Hz,
3
3
3
3
CH ), 7.56 (d, 6H, J = 8.5 Hz, CH ), 7.80 (d, 6H, J = 6.0 Hz, CH ), 8.80 (d, 6H, J = 6.0
Ar
Ar
Py
1
3
1
Hz, CH ). C NMR (125 MHz, CDCl ):
δ
(ppm) 86.1, 102.5, 116.0, 116.3 (q, J = 288
Py
3
CF
2
Hz), 124.6, 128.1, 134.4, 140.2, 142.5, 148.2, 162.2 (q, J = 38 Hz). HR-MALDI-MS
CF
+
(
DHB): calcd for C H N [(M – C F O ) ] 551.2214, found 551.2223.
3
9
27
4
6
9
6
Chromophore 14. The title compound was synthesized from 7 (100 mg, 0.29 mmol)
following the general procedure for pyridinium salts. Red solid. Yield 125 mg (93%). Mp:
1
3
1
89 °C. H NMR (500 MHz, CDCl ):
δ
(ppm) 6.95 (d, 1H, J = 16.0 Hz, CH ), 7.03 (d, 2H,
3
vin
3
3
J = 8.5 Hz, CH ), 7.12–7.16 (m, 6H, CH ), 7.30–7.34 (m, 4H, CH ), 7.44 (d, 2H, J = 8.5
Ar
Ar
Ar
3
3
3
Hz, CH ), 7.54 (d, 1H, J = 16.0 Hz, CH ), 7.77 (d, 2H, J = 6.5 Hz, CH ), 8.67 (d, 2H, J
Ar
vin
Py
1
3
1
=
6.5 Hz, CH ). C NMR (125 MHz, CDCl ): δ (ppm) 116.1 (q, J = 286 Hz), 119.5,
Py 3 CF

2
8
ACCEPTED MANUSCRIPT
2
1
21.2, 122.4, 126.0, 127.1, 129.7, 129.9, 141.2, 141.3, 146.6, 150.9, 154.8, 161.8 (q, J = 38
CF
+
Hz). HR-MALDI-MS (DHB): calcd for C H N [(M – C F O ) ] 349.1694, found 349.1699.
2
5
21
2
2
3
2
Electronic supplementary information (ESI) available: Experimental procedures, copies of
1
13
the H NMR and C NMR spectra of the new compounds, DSC thermographs, cyclic
voltammograms, crystallographic data, crystal structures, visualization of HOMO/LUMO
localizations, UV and PL spectra. Crystallographic data for structural analysis have been
deposited in the Cambridge Crystallographic Data Centre, CCDC no. 1522362, 1522363,
1
522364 and 1522365 for 1, 2, 3, and 10, respectively. Copies of this information may be
obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EY, UK
fax: +44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
(
http://www.ccdc.cam.ac.uk).
Acknowledgements
This research was supported by the Technology Agency of the Czech Republic (TE01020022,
Flexprint).

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