Original electroactive and fluorescent bichromophores based on non-conjugated tetrazine and triphenylamine derivatives: Towards more efficient fluorescent switches

Article abstract of DOI:10.1039/c5ra07253k

The synthesis, photophysical and electrochemical properties and their interplay as well as theoretical calculations studies of newly designed fluorescent and electroactive derivatives are described. These molecules are composed of two fluorophores: one triphenylamine, electron-rich unit, and one tetrazine, electron-poor unit, connected by two different links. While in the neutral state the bichromophores are not fluorescent, due to a photoinduced electron transfer from the triphenylamine unit to the tetrazine unit, the fluorescence is restored in the oxidative state (oxidation of the triphenylamine moiety).

Full text of DOI:10.1039/c5ra07253k

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Original electroactive and fluorescent
bichromophores based on non-conjugated
tetrazine and triphenylamine derivatives: towards
more efficient fluorescent switches†
Cite this: RSC Adv., 2015, 5, 49728
*
Cassandre Quinton, Valerie Alain-Rizzo, Cecile Dumas-Verdes, Gilles Clavier
´
´
*
and Pierre Audebert
The synthesis, photophysical and electrochemical properties and their interplay as well as theoretical
calculations studies of newly designed fluorescent and electroactive derivatives are described. These
molecules are composed of two fluorophores: one triphenylamine, electron-rich unit, and one tetrazine,
electron-poor unit, connected by two different links. While in the neutral state the bichromophores are
not fluorescent, due to a photoinduced electron transfer from the triphenylamine unit to the tetrazine
unit, the fluorescence is restored in the oxidative state (oxidation of the triphenylamine moiety).
Received 21st April 2015
Accepted 26th May 2015
DOI: 10.1039/c5ra07253k
www.rsc.org/advances
Introduction
For some years now, we have shown interest in the study of
uorescent electroactive chromophores based on tetrazine1–5 or
triphenylamine.6,7 These molecules present a different behav-
iour in their photophysical properties according to the redox
state of the molecule (neutral, oxidized or reduced state). For
example, interplay between uorescence and redox character-
istics has been studied in the case of N,N,N-tri-(4-methoxy-1,10-
biphenyl)amine and led to a reversible switching of the uo-
rescence.7 However, while there is interest and possible appli-
cations to study the reversible uorescence electrochemical
switch of a molecule composed of a single both uorescent and
electroactive unit,8–10 multiple uorophore systems11–15 present
their own advantages (e.g., on–off two states system, multi-
wavelength switch, more recyclable system since the chromo-
phore is not destroyed). Recently, we studied dyads composed
of a triphenylamine as electroactive donating group and a tet-
razine as uorophore accepting group.13,14 The goal was to get
tetrazine–triphenylamine dyads which behave as a redox
mediated off–on uorescence switch (Fig. 1). The major issue of
these bichromophores is that emission of tetrazine was weakly
restored upon oxidation with low uorescence quantum yields
because of a possible energy transfer.13 In order to avoid this
latter transfer and so to enhance the uorescence quantum
yield, design of new bichromophores with a bathochromic shi
Fig. 1 Design of two redox states system with different fluorescence
properties.
of the cation radical absorption has been explored. Thus we
have synthesised several dyads featuring one triphenylamine
moiety bearing different donating groups on their para position
(to insure the bathochromic shi)7 and a chlorotetrazine that
stands for the electron poor uorescent moiety (Fig. 1). Chlor-
oalkoxytetrazine are known to be more uorescent than dia-
lkoxytetrazine5,16 which explains why bichromophoric
compounds based on chlorotetrazine are more efficient.13 In
addition we have chosen a link composed of 3 or 4 atoms (C and
O atoms) instead of a unique oxygen atom because the phe-
noxytetrazine derivatives are not highly uorescent.17,18
Results and discussion
Synthesis
´
PPSM, CNRS UMR8531, ENS Cachan, UniverSud, 61 Avenue du President Wilson,
Designs of triphenylamine precursors were rationalized in order
to make possible nucleophilic aromatic monosubstitution of
3,6-dichloro-s-tetrazine, TzCl2 (Fig. 2). Knowing that TzCl2 can
undergo easily monosubstitution with alcohol compounds,1,5
we therefore decided to synthesize triphenylamine derivatives
94235 Cachan, France. E-mail: valerie.alain@ens-cachan.fr; pierre.audebert@
ens-cachan.fr; Fax: +33-1-47402454
† Electronic supplementary information (ESI) available: Electrochemical data,
uorescence
switching
experiments,
theoretical
calculations,
NMR
characterizations, HRMS characterizations. See DOI: 10.1039/c5ra07253k
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functionalized with a short chain ended with a primary alcohol
function. Triphenylamines are well known to form stable
cation-radicals7,19,20 but also to polymerize by their para posi-
tions when this latter remains unsubstituted.21,22 For our future
applications, it was thus necessary to also prepare triphenyl-
amine compounds bearing groups in the para positions of
phenyl groups such as bromo, methoxy phenyl or dimethyla-
minophenyl groups to avoid the possible polymerization.
Precursor compounds 5, 6, 7 and 8 were then targeted.
On the one hand, 2-(4-bromophenyl)-ethanol was protected
through an acetal function23 in a quantitative way to give 9
(Fig. 3). On the other hand, 2-bromoethanol was protected in its
THP adduct23 to give compound 10 in 84% yield. A Williamson
reaction between 10 and p-iodophenol with usual heating24 led
to product 11 in quasi-quantitative way.
The synthetic route to the nucleophilic triphenylamine
derivatives 5, 6, 7 and 8 is shown in Fig. 4. The brominated
intermediaries 9 or 11 were placed in the Suzuki–Miyaura25–28
reaction conditions with the corresponding triphenylamine
boronic acid to give the triphenylamine derivatives 12 and 13 in
good yields (respectively 84% and 91%).
Fig. 4 Synthetic route to nucleophilic triphenylamine derivatives 5, 6,
7 and 8.
The compounds 14 and 15 were then obtained by dibromi-
nation of 12 and 13 using N-bromosuccinimide.29 The presence
of bromine atoms in para positions on the triphenylamine
derivatives 14 and 15 opens the possibilities to several further
functionalizations. In particular, having on these para positions
more electron donating group could induce an absorption shi
of the cation-radical and we could thus avoid the uorescence
extinction due to an energy transfer which has already been
observed in the case of bromine or methyl substituents.13
Suzuki–Miyaura reactions were therefore realized between, on
one hand the dibrominated compound 14 or 15, and on the
other hand p-methoxyphenylboronic acid or p-dimethylamino-
phenylboronic acid to give the precursors 16, 17, 18 and 19.
They were then deprotected30,31 to give the nucleophilic triphe-
nylamine derivatives 5, 6, 7 and 8.
The bichromophoric derivatives 1, 2, 3 and 4 were synthe-
sized employing SNAr on TzCl2. Beneting from the pioneering
work of Hiskey and Chavez,32–34 multi-grams synthesis of TzCl2
has been previously optimized in our group.5 The nucleophilic
aromatic monosubstitution of TzCl2 has been achieved in the
presence of one equivalent of collidine, with a large variety of
nucleophiles, particularly with alcohols.4,35–40 The introduction
of one equivalent of nucleophiles 5, 6, 7 and 8 were realized on
TzCl2 at room temperature with the usual procedure,5 affording
compounds 1, 2, 3 and 4 in reasonable yields, from 43 to 83%
(Fig. 5).
Hence, the syntheses of four new bichromophoric
compounds based on tetrazine and triphenylamine moieties
have been successfully realized in few steps using the key SNAr
on 3,6-dichloro-s-tetrazine, TzCl2.
Electrochemical investigations
The redox properties of the bichromophores 1, 2, 3 and 4 were
investigated by cyclic voltammetry (CV). Electrochemical data
are summarized in Table 1. Concerning 1, 2 and 3, three well
Fig. 2 Design of nucleophilic triphenylamine derivatives.
Fig. 5 Synthetic routes to bichromophoric compounds 1, 2, 3 and 4
via SNAr on TzCl2.
Fig. 3 Synthetic route to protected precursors 9 and 11.
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Table 1 Electrochemical data for compounds 1, 2, 3 and 4. Potentials
are referenced to Fc+/Fc. All measurements in dichloromethane +0.1
M Bu4NPF6 on glassy carbon C
this is due to the shorter link (CH2–CH2–O compared to O–CH2–
CH2–O), or to the different electronegativity of the atoms (C
versus O). These conclusions, especially the ones concerning the
inuence of the triphenylamine through a non-conjugated link,
appear unusual for a two carbons non-conjugated link.
In conclusion, the two redox moieties are indeed electro-
active and behave independently in the various dyads.
Compounds
1
2
3
4
E
E
E
E
0/ꢀ1 (V)
1/0 (V)
2/1 (V)
3/2 (V)
ꢀ0.97
0.39
0.97
—
ꢀ0.82
0.54
1.4
ꢀ0.96
0.31
1.15
—
ꢀ1.27
0.13
0.48
—
0.66
Photophysical studies
The absorption spectra of these new synthesized compounds
dened redox systems can be identied corresponding to the were registered and the one of 1 is displayed in Fig. 7 as a typical
reduction of tetrazine moiety into its anion radical and to the example; the absorption data have been otherwise collected in
two successive oxidation of triphenylamine moiety (see Fig. 6 ESI.† The transitions types were determined from quantum
for 1 and ESI† for 2 and 3). The four potentials measured in the chemical calculations (TDDFT, data in Tables S1 and S3†).
case of 4 (see ESI†) correspond to the reduction of the tetrazine These bichromophores display three bands and their absorp-
moiety and to successive oxidation steps involving each amine tion properties are similar to the sum of the disconnected parts.
moiety through a one electron process, as we already observed For all compounds, there are two intense bands in the UV
on another triphenylamine derivative.6 The value of 0.13 V region which are attributed to p–p* transitions located both on
corresponds to the oxidation of the central nitrogen on triphe- tetrazine and triphenylamine units (see Fig. 8 for 1 and ESI† for
nylamine. This oxidation is the easiest one due to the electronic 2). We can note that the band localized at around 260 nm is not
delocalization with the phenyl rings. The two higher values dependent of the substituents on the triphenylamine (or the
correspond to the oxidations of the two dimethylamino moie- link) whereas the band localized between 326 and 345 nm is
ties, which are not independent. These peaks are fully reversible inuenced. The third band is located around 510 nm and
although the peak-to-peak separation is greater than 60 mV, due displays
a
weak molar absorption coefficient (around
to electron transfer kinetics as already mentioned for tetra- 700 L molꢀ1 cmꢀ1) because of a forbidden n–p* transition
zine.13,35,36 The CVs also conrm that substitution on the para centered on the tetrazine unit. This transition is very weakly
positions of the triphenylamine inhibits its polymerization. 4 sensitive to substituents effects on the triphenylamine
shows a rst oxidation potential lower than 3 because the moiety.1,4,13,14
dimethylamino group is more electron donor than the methoxy
Even if the triphenylamine and tetrazine units can be highly
group and, thus, make the oxidation easier. Similarly, 2 has a uorescent when they are disconnected, the bichromophoric
higher oxidation peak than 3 because 2 has an electron with- compounds 1–4 are very weakly uorescent in their neutral state
drawing bromine atom, instead of a methoxyphenyl group, as expected. This is due to a quenching by a photoinduced
which destabilizes the cation radical. Interestingly, the nature electron transfer from the triphenylamine to the tetrazine
of the substituents of the triphenylamine and the nature of the moiety because of the proximity of the two parts. Indeed this
link also inuence the reduction potential of the tetrazine. behaviour was previously observed in a bimolecular process in
Especially compound 4 which bears a highly donating triphe- solution4 and in some other bichromophoric compounds.13,14
nylamine displays a lower potential (more negative) than the For all bichromophoric compounds, the uorescence quantum
one of 3 which is itself lower than the one of 2, in agreement yields are much lower than 0.1. Estimation for 1, 2, 3 and 4 is
with successive replacement of a strong electron donor group
(dimethylamino) by a lower one (methoxy) and an electron
withdrawing bromine atom. In comparison, generic 3-(ada-
mantan-1-yl)methoxy)-6-chloro-s-tetrazine is reduced at ꢀ0.85
V.1 There is also an inuence of the linker. 1 presents a lower
(more negative) reduction potential than 2. This is not clear if
Fig. 6 Cyclic voltammetry of 1 (10ꢀ5 M) in dichloromethane +0.1 M Fig. 7 Molar absorption coefficient of compound 1 in dichloro-
Bu4NPF6 on glassy carbon C. Potentials are referenced to Fc+/Fc. Scan methane. Inset shows the molar absorption coefficient of 1 in 450–
rate: 80 mV sꢀ1
.
600 nm region.
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respectively. The excitation wavelength is 326 nm where both
triphenylamine and tetrazine units absorb. The emission
maxima localized at around 420 nm and the lifetimes corre-
spond to the triphenylamine core. The lifetimes of the precursor
6 are namely 1.23 and 0.023 ns. Despite the quenching, the
triphenylamine part still slightly emits, while the tetrazine
uorescence is completely quenched.
Redox-dependent spectroscopy
At neutral state, there is no uorescence of the bichromophoric
compounds in the tetrazine emission region but there is still
some remaining uorescence from the triphenylamine unit.
Fluorescence of both triphenylamine (electron donor moiety) or
tetrazine (electron acceptor moiety) parts are nearly or
completely cancelled out by an electron transfer from triphe-
nylamine to tetrazine. When triphenylamine will be oxidized,
the electron transfer should not occur and thus the uorescence
of tetrazine should be restored (Fig. 1). To check this assump-
tion, the triphenylamine was oxidized into its cation radical. We
chose a one-electron chemical oxidant: Cu(ClO4)2 was used as a
mild and clean oxidant and has been recently reported to
effectively generate arylaminium cation-radicals.6,13,14,42–44
Another advantage of using Cu(ClO4)2 is that it gives no
absorption or emission in the UV-visible domain at low
concentrations and its reduction potential in acetonitrile is 0.7
V vs. Fc/Fc+, which matches well with the rst oxidation
potentials of 1, 2, 3 and 4. The cation-radicals of the triphe-
nylamine derivatives are thus generated using Cu(ClO4)2 in
acetonitrile, this being the most suitable solvent to dissolve
both the oxidant and the bichromophoric compounds, and are
characterized by absorption and emission spectroscopies.
Upon titration with Cu(ClO4)2, two absorption bands in the
UV region (l ¼ 257 and 326 nm) decrease whereas four bands
gradually appear at 291, 434, 718 and 991 nm for 2 (Fig. 9; ESI†
for 1, 3 and 4). The new absorption bands are attributed to the
formation of the cation-radical centered on the triphenylamine
core by comparison with the absorption spectrum of the radical
cation of triphenylamine derivatives.7 One can also observe the
appearance of four isosbestic points at 240, 271, 297 and 367
Fig. 8 Representation of the energy levels and the main molecular
orbitals involved in the electronic transitions of 1.
collected in Table 2. For example, the uorescence quantum
yield of 3 is 0.008 even when it is 0.37 and 0.38 for N,N,N-tri-
(40-methoxy-1,10-biphenyl)amine7 and 3-chloro-6-methoxytetrazine1
Table 2 Absorption wavelength (l, nm), molar absorption coefficient
(3, L molꢀ1 cmꢀ1), emission wavelength (lem, nm), fluorescence
quantum yield (F) and fluorescence lifetime (s, ns) for 1, 2, 3 and 4 in
acetonitrile
Compounds
labs
3
lem
F
s
1
255
342
520
257
326
511
258
337
511
n.d.b
345
507
43 400
68 600
690
30 200
55 000
690
418
0.004a
1.63 and 0.010b
2
3
4
415
417
426
0.001a
0.008a
0.06a
1.18 and 0.018
1.61 and 0.015
n.d.b
36 200
57 800
670
n.d.b
43 500
690
a
Fig. 9 Absorption spectra recorded upon oxidation of 2 by Cu(ClO4)2
Fluorescence quantum yields measured with quinine sulfate in H2SO4
b
in CH3CN as a function of R ¼ [CuII]/[2], [2] ¼ 1.1 ꢁ 10ꢀ5 mol Lꢀ1
.
(0.5 N) as a standard (FF ¼ 0.546),41 lexc ¼ 326 nm. Not determined.
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nm for 2 in agreement with the existence of an equilibrium
Emission spectra upon gradual addition of Cu(ClO4)2 are
between the triphenylamine derivative and its cation-radical. displayed in Fig. 11 for compound 2 (see ESI† for 1, 3 and 4). A
Since the absorption spectra with 1.26 and 1.47 equivalent of decrease of the band localized at 415 nm (respectively 429 and
oxidant overlap, oxidation is complete when 1.26 equivalents of 417 for 1 and 3) typical of the remaining triphenylamine emis-
Cu(ClO4)2 is added for 2. Cu(ClO4)2 is clearly not strong enough sion is observed. Indeed the quantity of triphenylamine
to perform further oxidations. Similar behaviours upon oxida- diminished upon oxidation and its cation-radical does not emit.
tion have been noticed in the cases of 1, 3 and 4. Note that in the In the case of 4 a more complex evolution of the uorescence is
case of 4 at least three equivalents of oxidant are necessary to observed that is attributed to the formation of various oxidized
complete the compound conversion, in agreement with the forms of the triphenyl amine. Similar behavior has been studied
three oxidation potentials which all lie below 0.7 V.
It is important to note that these four oxidized bichomo- (N0,N0-dimethyl)-10,100-biphenyl]-4-anisidine.6
by us on the related triphenylamine compound N,N-di-[400-
phoric compounds 1, 2, 3 and 4 have a really weak absorption
A uorescence band localized at 550 nm for 2 (558 nm for 3)
between 500 and 625 nm, which corresponds to the uores- appears concomitantly to the disappearance of the emission of
cence domain of the tetrazine unit. In the case of previously the triphenylamine. The emission wavelength and the lifetime
reported compounds having weaker donor substituents on the of 153 ns for 2 (155 ns for 3) are typical of the tetrazine emission.
triphenylamine,13,14 an energy transfer towards the cation- It has thus been possible to regenerate the tetrazine uores-
radical (made possible by an overlap of its absorbance and its cence with compounds 2 and 3 upon oxidation of the triphe-
emission) partially quenches the uorescence of the tetrazine at nylamine moiety with Cu(II). Unfortunately the recovery is only
the oxidized state (through FRET). From this perspective, these partial. In the case of 1 and 4, the tetrazine uorescence could
four compounds demonstrate
compared to the previous studied bichromophoric compounds probably not strong enough and could be hidden by the tri-
thanks to the donor substituents on the triphenylamine part. phenylamine uorescence. We did not try to oxidize electro-
a signicant improvement not be restored. For compound 4, the tetrazine uorescence is
The uorescence spectra were recorded upon oxidation in chemically the compounds in a suitable cell, because it was
the same [CuII]/[dyad] ratios as those used for the spectropho- likely that the electrochemical switch of uorescence (electro-
tometric titrations. In order to determine the ideal excitation uorochromism) would be observable with difficulties in these
wavelength, excitation spectra of the oxidized bichromophoric conditions, because of the partial recovery.
compounds were measured (as exemplied for 3 on Fig. 10).
In order to explain the evolution of the uorescence of these
In general, isosbestic points are oen chosen for excitation. bichromophoric compounds upon oxidation, we identied the
But in our case, the tetrazine part does not absorb at all the relative redox properties of the various neutral, ionic and
isosbestic points. Therefore they are not suitable for excitation. excited states of both chromophores thanks to the electro-
The maximal absorption wavelength is around 326 nm in the chemical and spectroscopic data. The results are summarized
excitation spectra for all these compounds. This is the reason on a redox scale in Fig. 12. The value of the potential Tz*/Tzcꢀ
why this wavelength has been chosen as the excitation wave- has been determined according to the formula:
length for the study of the changes of the emission upon
oxidation. The diminution of absorption at 326 nm during the
ET0z*=Tzꢂꢀ ¼ ET0z=Tzꢂꢀ þ DE0ꢀ0ðTzÞ
where ET0z*=Tzꢂꢀ is the reduction potential of the bichromophoric
compound in its excited state and DE0–0(Tz) is the difference
process comes from the oxidation of the triphenylamine in its
cation-radical, but the quantity of tetrazine remains the same
and the number of photons absorbed by tetrazine core remains
constant.
Fig. 11 Emission spectra recorded upon oxidation of 2 by Cu(ClO4)2 in
Fig. 10 Absorption emission (lexc ¼ 330 nm) and excitation (lem ¼ 560 CH3CN as a function of R ¼ [CuII]/[2], [2] ¼ 1.1 ꢁ 10ꢀ5 mol Lꢀ1, lexc
¼
nm) of oxidized 3 in acetonitrile.
326 nm.
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second possible unexpected PET. Our previous studies showed
that triphenylamine should be substituted by electron rich
groups in order to shi the absorption band of the cation-
radical at higher wavelengths than the emission wavelength of
the tetrazine. Thus, the energy transfer that impeded the
recovery of the tetrazine uorescence could be avoided.
Conversely, the present study demonstrates that the substitu-
ents of the triphenylamine should not be too strong donors in
order to prevent a photoinduced electron transfer between the
tetrazine and the cation-radical of the triphenylamine, which is
the reason why the uorescence of the tetrazine is only partially
restored in the present dyads upon oxidation. Both studies
highlight the necessity for a ne tuning of the electronic prop-
erties of both moieties to achieve efficient electro-
uorochromism in dyads.
However, a true uorescence switch by oxidation was
demonstrated featuring a neutral state with blue uorescence
and a stable cation-radical state with yellow uorescence for
molecular dyads 2 and 3. We are currently trying to achieve a
third state with these dyads with enhanced uorescence of the
triphenylamine moiety by reducing the tetrazine ring. Fluores-
cence modulation by electrochemistry10,45 is also currently
under study in our laboratory. Further theoretical calculations
are also being investigated in order to precisely design new
triphenylamine derivatives which could give more efficient
electrouorochromic dyads.
Fig. 12 Redox scale for the neutral, ionic and excited-state tetrazine
(Tz) and triphenylamine (TPA) couples vs. ferrocene.
between the lower vibrational energy levels of the excited and
fundamental states of the tetrazine part and estimated from the
n–p* band.
The lack of uorescence corresponding to the tetrazine in
the bichromophoric species can be explained when one looks at
all redox potentials. Indeed, in any case, the absorption of one
photon leads to an excited state in which a photoinduced
electron-transfer (PET) is thermodynamically favored from the
triphenylamine or its radical-cation to the tetrazine. This is due
to the donating substituents on the triphenylamine part which
lowers the rst two oxidation potentials combine with the
exceptionally high reduction potential of the tetrazine in its
excited state. The magnitude of the difference
Experimental section
Spectroscopic measurements
ET0z*=Tzꢂꢀ ꢀ ET0PA2þ
=TPAꢂþ
can be related to the retrieval or not of the uorescence in the
dyads. For 2 this difference is quite small, indicating that in this
case the PET when the triphenylamine is oxidized is less
favorable and allows a partial recovery of the tetrazine uores-
cence. This difference is larger for 3 but not enough for a
complete PET leading to a marginal uorescence recovery.
Finally in the case of 1 and 4 the difference is too large and no
uorescence from the tetrazine could be restored because of a
favorable PET process.
UV-visible absorption spectra were recorded on a Cary 5000
spectrophotometer in 1 cm optical length quartz cuvettes.
Corrected emission spectra were obtained on a Jobin-Yvon
Horiba Spex FluoroMax-3 spectrouorometer. Acetonitrile
(Aldrich, spectrometric grade or SDS, spectrometric grade) was
employed as solvent for absorption and uorescence measure-
ments. The uorescence quantum yields were determined by
using quinine sulfate in H2SO4 (0.5 N) as a standard (FF
¼
0.546). The estimated experimental error is less than 10%. For
the emission measurements, a right-angle conguration was
used and the absorbance at the excitation wavelength are kept
below 0.1 in order to avoid reabsorption artefacts.
Conclusions
New bichromophoric compounds for improved electro-
uorochromic properties based on triphenylamine and tetra-
zine cores were designed and synthesized and their
Electrochemistry
photophysical and electrochemical properties have been Solvents (SDS, HPLC grade) and electrolyte salts (tetrabuty-
investigated. The generation of triphenylaminium cations could lammonium hexauorophosphate from Fluka, puriss.) were
be achieved by chemical oxidation and their photophysical used without further purication. Cyclic voltammetry was per-
properties have been investigated too. It appears that the formed in a three-electrode cell with a potentiostat (CH
absorption properties are similar to the disconnected parts (this Instruments 600) driven by a PC. Carbon electrode (1 mm
fact is supported by theoretical calculations). As expected, the diameter) was used as working electrode, whereas platinum
bichromophores exhibit very low uorescence quantum yields wire and Ag+ (0.01 M in acetonitrile)/Ag were used, respectively,
in their neutral state in the blue region, because of a photoin- as the counter and reference electrodes. All the investigated
duced electron transfer from the triphenylamine to the tetra- solutions were deaerated by argon-bubbling for at least 2 min
zine. But upon one-electron oxidation of the triphenyl amine before performing the electrochemical measurements. The
moiety, emission of tetrazine was restored in two cases though reference electrode was checked versus ferrocene as recom-
uorescence quantum yields remain moderate because of a mended by IUPAC.
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and recrystallized N-bromosuccinimide (2.2 eq). Reaction
mixture was stirred at room temperature without light until the
triphenylamine derivative had disappeared as judged by TLC
(few hours). The reaction mixture was cooled to room temper-
ature and distilled water was added. It was extracted with
diethylether, washed with saturated solution of NaCl, dried over
anhydrous Na2SO4, ltered and concentrated under reduced
pressure. The crude product was puried by a silica gel column
chromatography.
Procedure D for deprotection of alcohol protected with THP.
In a round-bottom-ask were placed protected alcohol (1.0 eq)
and p-toluenesulfonic acid (0.1 eq) in a mixture of solvents
chloroform/methanol (1 : 1, 0.02 M). The reaction mixture was
then stirred at room temperature until the starting materials
Quantum chemical calculations
Calculations were performed with the Gaussian 03 at the MESO
calculation centre of the ENS Cachan (Nec TX7 with 32
processors of type Itanium 2). Molecules were drawn with the
Gaussview 03 soware using included templates and their
geometry optimized at the PBE0 level of theory. Infrared spectra
were calculated on the nal geometry to ascertain that a
minimum was obtained (no negative frequencies). Time-
dependant density functional theory (TDDFT) calculations at
the PBE0 level of theory with the 6-31+g(d) basis set were
subsequently performed.
Synthesis
Reagents were commercially available from Aldrich and used had disappeared as judged by TLC (few hours). Volatile
without further purication. Column chromatography was compounds were removed by concentration under reduced
performed with SDS 0.040-0.063 mm silica gel. All compounds pressure and Na2CO3 solution was added. It was extracted with
were characterized by the usual analytical methods: 1H, 13C dichloromethane, washed with a saturated NaCl solution, dried
NMR spectra were recorded with a JEOL ECS (400 MHz) spec- over anhydrous Na2SO4, ltered and concentrated under
trometer. All chemical shis are referenced to the solvent peak reduced pressure. The crude product was puried by a silica gel
(J values are given in Hz). Melting points were measured with a column chromatography.
Koer melting-point apparatus. IR spectra were recorded with a
Procedure E for SNAr on 3,6-dichloro-s-tetrazine TzCl2. To a
Nicolet Avatar 330 FT-IR spectrometer. This work has beneted solution of alcohol compound (1.0 eq, 0.05 M) in anhydrous
from the facilities and expertise of the Small Molecule Mass CH2Cl2 were added 3,6-dichloro-s-tetrazine (1.0 eq), and 2,4,6-
Spectrometry platform of IMAGIF (Centre de Recherche de Gif – collidine (1.0 eq). The mixture was stirred at room temperature
http://www.imagif.cnrs.fr).
3,6-Dichloro-s-tetrazine was synthesized as previously crude product was puried by
described by our group.5
for 1 hour then concentrated under reduced pressure. The
silica gel column
chromatography.
3-Chloro-6-([400-([4000-(dimethoxy)-1,10-biphenyl]amine)-10,100-
a
Procedure A for protection of alcohol with THP. In a round-
bottom-ask were placed p-toluenesulfonic acid (1 mol%), and biphenyl]ethoxy)-s-tetrazine (1). The procedure E was applied
dihydropyrane (1.5 eq) in chloroform. The alcohol compound using
N,N-di-(4-methoxy-10,100-biphenyl)-N-(4-[20-ethanol]
(1.0 eq, 1.0 M) was added dropwise. The mixture was then biphenyl)amine 5 (230 mg, 0.296 mmol, 1.0 eq). The crude
stirred at room temperature until the starting materials had product was puried by a silica gel column chromatography
disappeared as judged by TLC (few hours). The mixture was (petroleum ether/CH2Cl2: 3/7 to petroleum ether/CH2Cl2: 5/5) to
1
ꢃ
poured into an aqueous solution of NaHCO3 (2 mol%). The give a purple solid (143 mg, 83%). m.p.: 119 C; H NMR (400
mixture was stirred at room temperature for 1 hour. The solid MHz, CDCl3): d (ppm) ¼ 7.57–7.42 (m, 12H), 7.37 (d, J ¼ 8.2 Hz,
was ltrated and washed with dichloromethane and the ltrate 2H), 7.23–7.20 (m, 6H), 6.98 (d, J ¼ 8.2 Hz, 4H), 4.87 (t, J ¼ 6.9
was concentrated under reduced pressure. The crude product Hz, 2H), 3.85 (s, 6H), 3.27 (t, J ¼ 6.9 Hz, 2H); 13C NMR (100 MHz,
was puried by a silica gel column chromatography.
CDCl3): d (ppm) ¼ 166.7, 164.4, 159.0, 147.2, 146.4, 139.6, 135.5,
Procedure B for Suzuki–Miyaura cross-coupling reaction. 135.3, 134.8, 133.3, 129.7, 127.9, 127.6, 127.1, 124.8, 124.2,
Into a Schlenk-ask were placed the halogenated compound 114.4, 71.2, 55.5, 34.8; IR (cmꢀ1): 1601, 1494, 1453, 1344, 1326,
(1.0 eq, 0.06 M), toluene and the tetrakis(triphenylphosphine) 1281, 1248, 1178, 1040, 999, 819; HRMS-ESI: calcd for M ¼
palladium(0) Pd(PPh3)4 (2.5 mol% per substitution) under
C42H34N5O3Cl 691.2350 (100%), 692.2384 (45%), 693.2321
argon. The reaction mixture was stirred at room temperature for (49%), found 691.2364 (100%), 692.2396 (52%), 693.2365 (48%);
15 minutes and then were added the solutions of boronic acid UV-vis (CH3CN): lmax(3) ¼ 345 (68 600 L cmꢀ1 molꢀ1), 520 (690
(1.1 eq per substitution, 1.6 M) in methanol and Na2CO3 (2.0 eq L cmꢀ1 molꢀ1), lem(FF) ¼ 418 (0.004) in CH3CN, s ¼ 1.63, 0.010
per substitution, 2.0 M) in distilled water. The reaction mixture ns; Eꢃ (C, CH2Cl2) vs. ferrocene: ꢀ0.97 V, 0.39 V.
3-[20-(400-[N-Bromophenyl-N-(4000-methoxy-1000,10000-biphenyl)-
ꢃ
was stirred at 80 C until the halogenated compound had dis-
appeared as judged by TLC (around one day). The reaction amine]-10,100-biphenoxy)ethoxy]-6-chloro-s-tetrazine (2). The
mixture was cooled to room temperature and a saturated procedure
was applied using N-(4-bromophenyl)-N-(4-
E
aqueous NH4Cl solution was added. The medium was extracted methoxy-10,100-biphenyl)-N-(4-[20-ethoxy]-10,100-biphenoxy)amine
with dichloromethane, dried over anhydrous Na2SO4, ltered 6 (360 mg, 0.635 mmol, 1.0 eq). The crude product was puried
and concentrated under reduced pressure. The crude product by a silica gel column chromatography (petroleum ether/
was puried by a silica gel column chromatography.
CH2Cl2: 3/7) to give a purple solid (298 mg, 69%). m.p.: 165 ꢃC;
Procedure C for bromination in para positions of a triphe- 1H NMR (400 MHz, CDCl3): d (ppm) ¼ 7.52 (d, J ¼ 8.7 Hz, 2H),
nylamine derivative. In a round-bottom-ask were placed tri- 7.51 (d, J ¼ 8.7 Hz, 2H), 7.46 (d, J ¼ 8.7 Hz, 2H), 7.45 (d, J ¼ 8.7
phenylamine derivative (1.0 eq, 0.07 M), dimethylformamide Hz, 2H), 7.36 (d, J ¼ 9.2 Hz, 2H), 7.16 (d, J ¼ 8.2 Hz, 2H), 7.15 (d,
49734 | RSC Adv., 2015, 5, 49728–49738
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J ¼ 8.7 Hz, 2H), 7.03 (d, J ¼ 8.7 Hz, 2H), 6.99 (d, J ¼ 8.7 Hz, 2H), 74%). m.p.: <50 ꢃC; 1H NMR (400 MHz, CDCl3): d (ppm) ¼ 7.55–
6.97 (d, J ¼ 9.2 Hz, 2H), 5.02 (t, J ¼ 4.6 Hz, 2H), 4.48 (t, J ¼ 4.6 Hz, 7.47 (m, 14H), 7.30 (d, J ¼ 8.2 Hz, 2H), 6.97 (m, 8H), 3.91 (t, J ¼
2H), 3.85 (s, 3H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 166.7, 3.5 Hz, 1H), 3.85 (s, 6H), 2.92 (s, 2H); 13C NMR (100 MHz,
164.7, 159.0, 157.5, 146.9, 146.3, 146.0, 135.8, 135.4, 134.0, CDCl3): d (ppm) ¼ 158.9, 146.9, 146.3, 138.9, 137.2, 135.3, 135.0,
133.1, 132.3, 127.9, 127.8, 127.6, 127.6, 125.4, 124.7, 124.6, 133.2, 129.6, 127.8, 127.5, 126.9, 124.6, 124.1, 114.3, 63.7, 55.4,
115.1, 115.0, 114.3, 68.9, 65.5, 55.4; IR (cmꢀ1): 1607, 1583, 1485, 38.9.
1461, 1442, 1375, 1345, 1319, 1280, 1246, 1198, 1039, 930, 818;
N-(4-Bromophenyl)-N-(4-methoxy-10,100-biphenyl)-N-(4-[20-
HRMS-ESI: calcd for M ¼ C35H27N5O3ClBr [M + H]+ 680.1064, ethoxy]-10,100-biphenoxy)amine (6). The procedure D was
found 680.1035; UV-vis (CH3CN): lmax(3) ¼ 257 (30 200 L cmꢀ1 applied using N-(4-bromophenyl)-N-(4-methoxy-10,100-biphenyl)-
molꢀ1), 326 (55 000 L cmꢀ1 molꢀ1), 511 (690 L cmꢀ1 molꢀ1), N-(4-[20-(tetrahydro-2H-pyran-200-yloxy)ethoxy]biphenyl)amine 17
lem ¼ 412 in CH3CN, s ¼ 1.18, 0.018 ns; Eꢃ (C, CH2Cl2) vs. (400 mg, 0.615 mmol, 1.0 eq). The crude product was puried by
ferrocene: ꢀ0.82, 0.54, 1.40 V.
a silica gel column chromatography (CH2Cl2/EtOH: 9.5/0.5) to
1
3-Chloro-6-[20-(400-[N,N-di-(4000-methoxy-1000,10000-biphenyl)amine]- give a white solid (347 mg, quant). m.p.: 121 C; H NMR (400
10,100-biphenoxy)ethoxy]-s-tetrazine (3). The procedure E was MHz, CDCl3): d (ppm) ¼ 7.52 (d, J ¼ 8.7 Hz, 4H), 7.47 (d, J ¼ 8.7
applied using N,N-(4-methoxy-10,100-biphenyl)-N-[4-(20-ethoxy)- Hz, 4H), 7.36 (d, J ¼ 9.2 Hz, 2H), 7.16 (d, J ¼ 8.7 Hz, 4H), 7.03 (d,
10,100-biphenoxy]amine 7 (44 mg, 0.074 mmol, 1.0 eq). The crude J ¼ 8.7 Hz, 2H), 7.00 (d, J ¼ 8.7 Hz, 2H), 6.98 (d, J ¼ 8.7 Hz, 2H),
ꢃ
product was puried by a silica gel column chromatography 4.13 (t, J ¼ 4.6 Hz, 2H), 4.00 (t, J ¼ 4.6 Hz, 2H), 3.87 (s, 3H); 13
C
(petroleum ether/CH2Cl2: 2/8) to give a purple solid (42 mg, NMR (100 MHz, CDCl3): d (ppm) ¼ 158.9, 157.9, 146.7, 146.0,
81%). m.p.: 145 ꢃC; 1H NMR (400 MHz, CDCl3): d (ppm) ¼ 7.52 145.9, 135.6, 135.5, 133.3, 132.9, 132.2, 127.8, 127.7 (2 signals),
(m, 6H), 7.47 (d, J ¼ 8.7 Hz, 4H), 7.46 (d, J ¼ 8.7 Hz, 2H), 7.20 (m, 127.5, 125.2, 124.5, 124.5, 114.9, 114.2, 69.2, 61.3, 55.3; IR
6H), 6.99 (d, J ¼ 8.7 Hz, 2H), 6.97 (d, J ¼ 8.7 Hz, 4H), 5.01 (t, J ¼ (cmꢀ1): 2950, 1608, 1585, 1493, 1485, 1316, 1285, 1251, 1177,
4.6 Hz, 2H), 4.47 (t, J ¼ 4.6 Hz, 2H), 3.85 (s, 6H); 13C NMR (100 1162, 1136, 1071, 1034, 969, 925; UV-vis (CH3CN): lmax(3) ¼ 256
MHz, CDCl3): d (ppm) ¼ 166.7, 164.7, 159.0, 157.5, 146.7, 146.4, (22 600 L cmꢀ1 molꢀ1), 327 (39 400 L cmꢀ1 molꢀ1), lem(FF) ¼
135.3, 134.9, 134.2, 133.3, 127.9, 127.8, 127.5, 124.6, 124.4, 411 (0.06) in CH3CN, s ¼ 1.20, 0.023 ns.
115.0, 114.3, 68.9, 65.5, 55.4; IR (cmꢀ1): 2916, 2850, 1602, 1493,
N,N-(4-Methoxy-10,100-biphenyl)-N-[4-(20-ethoxy)-10,100-biphenoxy]-
1381, 1327, 1246, 1197, 932, 821; HRMS-ESI: calcd for M ¼ amine (7). The procedure D was applied using N,N-di-(4-
C
42H34N5O4Cl [M]c+ 707.2299 (100%), 708.2333 (45%), found methoxy-10,100-biphenyl)-N-(4-[20-(tetrahydro-2H-pyran-200-yloxy)-
707.2313 (100%), 708.2362 (48%); UV-vis (CH3CN): lmax(3) ¼ 260 ethoxy]biphenyl)amine 18 (195 mg, 0.288 mmol, 1.0 eq). The
(36 500 L cmꢀ1 molꢀ1), 336 (58 400 L cmꢀ1 molꢀ1), 511 (710 L crude product was puried by a silica gel column chromatog-
cmꢀ1 molꢀ1), lem(FF) ¼ 418 (0.01) in CH3CN, s ¼ 1.61, 0.015 ns; raphy (CH2Cl2/EtOH: 9.9/0.1) to give a white solid (44 mg, 26%).
1
ꢃ
Eꢃ (C, CH2Cl2) vs. ferrocene: ꢀ0.96, 0.31, 1.15 V.
m.p.: <50 C; H NMR (400 MHz, CDCl3): d (ppm) ¼ 7.53 (m,
3-Chloro-6-[400-(N,N-di-[4000-(dimethylamino)-1,10-biphenyl]- 6H), 7.47 (m, 6H), 7.21 (m, 6H), 6.99 (d, J ¼ 8.7 Hz, 2H), 6.98 (d,
amine)-10,100-biphenoxy]ethoxy)-s-tetrazine (4). The procedure J ¼ 8.7 Hz, 4H), 4.12 (t, J ¼ 4.4 Hz, 2H), 4.00 (t, J ¼ 4.4 Hz, 2H),
E was applied using 2-[400-(N,N-di-[4000-(dimethylamino)-1,10- 3.86 (s, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 158.9, 158.0,
biphenyl]amine)-10,100-biphenoxy]ethanol 8 (25 mg, 0.040 mmol, 146.6, 146.4, 135.3, 135.0, 133.8, 133.3, 127.9, 127.8, 127.5,
1.0 eq). The crude product was puried by a silica gel column 124.5, 124.4, 115.0, 114.3, 69.4, 61.6, 55.4; IR (cmꢀ1): 1602,
chromatography (petroleum ether/CH2Cl2: 3/7 to CH2Cl2/EtOH: 1494, 1245, 1176.
1
9.9/0.1) to give a purple solid (13 mg, 43%). m.p.: 122 ꢃC; H
2-[400-(N,N-Di-[4000-(dimethylamino)-1,10-biphenyl]amine)-10,100-
NMR (400 MHz, CDCl3): d (ppm) ¼ 7.52–7.45 (m, 12H), 7.26– biphenoxy]ethanol (8). The procedure D was applied using N,N-
7.20 (m, 6H), 6.99 (d, J ¼ 8.7 Hz, 2H), 6.90 (d, J ¼ 8.2 Hz, 4H), di-[400-(N0,N0-dimethyl)-10,100-biphenyl]-N-(400-(2-(tetrahydro-2H-
5.03 (t, J ¼ 4.4 Hz, 2H), 4.49 (t, J ¼ 4.4 Hz, 2H), 3.01 (s, 12H); 13
C
pyran-2-yloxy)ethoxy)-10,100-biphenyl)amine 19 (81 mg, 0.12
NMR (100 MHz, CDCl3): d (ppm) ¼ 166.7, 164.7, 157.4, 146.8, mmol, 1.0 eq). The crude product was puried by a silica gel
146.0, 134.6, 134.3, 133.9, 128.0, 127.9, 127.5, 127.1, 124.6, column chromatography (CH2Cl2/EtOH: 9.9/0.1) to give a white
124.2, 115.0, 114.9, 68.9, 65.5, 41.2; IR (cmꢀ1): 2917, 2850, 1607, solid (15 mg, 21%). m.p.: <50 C; H NMR (400 MHz, CDCl3): d
1
ꢃ
1494, 1344, 1323, 1197, 1113, 1041, 946, 813; HRMS-ESI: calcd (ppm) ¼ 7.53–7.45 (m, 12H); 7.21–7.18 (m, 6H); 6.98 (d, J ¼ 8.7
for M ¼ C44H40N7O2Cl [M]c+ 733.2932 (100%), 734.2966 (47%), Hz, 2H), 6.83 (d, J ¼ 8.7 Hz, 4H), 4.13 (t, J ¼ 4.6 Hz, 2H), 4.00 (t, J ¼
735.2903 (32%), 736.2936 (15%), found 733.2949 (100%), 4.6 Hz, 2H), 3.00 (s, 12H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼
734.3003 (47%), 735.2972 (44%), 736.2966 (24%); UV-vis 157.9, 149.7, 146.8, 146.0, 135.8, 134.7, 133.9, 132.3, 127.8, 127.4,
(CH3CN): lmax(3) ¼ 345 (43 500 L cmꢀ1 molꢀ1), 504 (690 127.1, 124.6, 124.1, 115.0, 113.1, 68.9, 65.5, 41.2.
L cmꢀ1 molꢀ1), lem(FF) ¼ 426 (0.06) in CH3CN, Eꢃ (C, CH2Cl2) vs.
ferrocene: ꢀ1.27, 0.13, 0.48, 0.66 V.
2-(40-Bromophenylethoxy)tetrahydro-2H-pyran
procedure A was applied using 4-bromophenylethanol (1.00 g,
(9).
The
N,N-di-(4-methoxy-10,100-biphenyl)-N-(4-[20-ethanol]biphenyl)- 4.97 mmol, 1.0 eq). The crude product was puried by a silica
amine (5). The procedure D was applied using N,N-di-(4- gel column chromatography (petroleum ether/CH2Cl2: 2/8) to
methoxy-10,100-biphenyl)-N-(4-[20-(tetrahydro-2H-pyran-200-yloxy)- give a colorless liquid (1.41 g, quant). 1H NMR (400 MHz,
ethyl]biphenyl)amine 16 (264 mg, 0.400 mmol, 1.0 eq). The CDCl3): d (ppm) ¼ 7.40 (d, J ¼ 8.7 Hz, 2H), 7.12 (d, J ¼ 8.7 Hz,
crude product was puried by a silica gel column chromatog- 2H), 4.57 (t, J ¼ 3.2 Hz, 1H), 3.95–3.50 (m, 6H), 2.86 (t, J ¼ 6.9 Hz,
raphy (CH2Cl2/EtOH: 9.9/0.1) to give a white solid (172 mg, 2H), 1.80–1.48 (m, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼
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138.4, 131.4, 130.9, 120.1, 98.9, 68.0, 62.3, 35.9, 30.8, 25.5, 19.6; 1.92–1.52 (m, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 158.3,
IR (cmꢀ1): 2941, 2869, 1487, 1352, 1199, 1135, 1120, 1081, 1072, 147.9, 146.7, 135.1, 133.5, 129.4, 127.8, 127.4, 124.3, 122.9,
1011, 972, 907, 870, 814.
115.1, 99.1, 67.6, 66.0, 62.3, 30.6, 25.5, 19.5; IR (cmꢀ1): 2951;
2-(20-Bromoethoxy)tetrahydro-2H-pyrane (10). The procedure 1586; 1488, 1456; 1316, 1284, 1252; 1162, 1137, 1119; 1070,
A was applied using bromoethanol (4.80 mL, 68.2 mmol, 1.0 eq). 1034; 986, 926, 885, 842, 818.
The crude product was puried by a silica gel column chro-
2-[20-(400-[4000-N,N-Di-(40000-bromophenyl)aniline]phenyl)ethoxy]-
matography (cyclohexane/AcOEt: 9/1) to give a colorless liquid tetrahydro-2H-pyrane (14). The procedure C was applied using
(12.0 g, 84%). 1H NMR (400 MHz, CDCl3): d (ppm) ¼ 4.66 (t, J ¼ 2-[40-(400-triphenylamine)phenylethoxy]tetrahydro-2H-pyran 12
3.4 Hz, 1H), 4.01 (t, J ¼ 5.5 Hz, 2H), 3.98 (t, J ¼ 5.5 Hz, 2H), 3.87 (1.04 g, 2.23 mmol, 1.0 eq). The crude product was puried by a
(td, J ¼ 8.7, 3.7 Hz, 2H), 3.76 (tt, J ¼ 6.4, 6.4 Hz, 2H), 3.74 (tt, J ¼ silica gel column chromatography (petroleum ether/CH2Cl2: 3/
6.4, 6.4 Hz, 2H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 99.0, 7) to a give a beige solid (1.39 g, quant). m.p.: < 50 ꢃC; 1H
67.6, 62.4, 30.1, 30.5, 25.5, 19.4; IR (cmꢀ1): 2971, 2912, 2850, NMR (400 MHz, CDCl3): d (ppm) ¼ 7.50 (d, J ¼ 8.2 Hz, 2H), 7.48
1454, 1438, 1183, 1120, 1068, 930, 907, 883, 869, 852, 837, 814. (d, J ¼ 8.7 Hz, 2H), 7.36 (d, J ¼ 9.2 Hz, 4H), 7.31 (d, J ¼ 8.2 Hz,
2-[20-(400-Iodophenoxy)ethoxy]tetrahydro-2H-pyrane (11). In a 2H), 7.11 (d, J ¼ 8.7 Hz, 2H), 6.98 (d, J ¼ 8.7 Hz, 4H), 4.63 (t, J ¼
round-bottom-ask were placed 2-(20-bromoethoxy)tetrahydro- 3.6 Hz, 1H), 4.00–3.48 (m, 4H), 2.96 (t, J ¼ 7.1 Hz), 1.86–1.51 (m,
2H-pyrane 10 (2.14 g, 10.2 mmol, 1.1 eq), dimethylformamide 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 146.5, 146.0, 138.3,
(100 mL), 4-iodophenol (2.02 g, 9.18 mmol, 1.0 eq) and potas- 138.2, 136.3, 132.5, 129.6, 128.0, 126.7, 125.6, 124.6, 115.7, 98.9,
sium carbonate (1.54 g, 11.1 mmol, 1.2 eq). The reaction 68.3, 62.3, 36.1, 30.8, 25.6, 19.6; IR (cmꢀ1): 2940, 1578, 1484,
mixture was then stirred at 65 ꢃC for 20 hours. Volatile 1313, 1284, 1135, 1120, 1071, 1030, 1006, 816.
compounds were removed by concentration under reduced
2-[20-(400-[4000-N,N-Di-(40000-bromophenyl)aniline]phenoxy)ethoxy]-
pressure and distilled water (100 mL) was added. The medium tetrahydro-2H-pyrane (15). The procedure C was applied using
was extracted with dichloromethane (4 ꢁ 100 mL), washed with 2-(20-[400-(4000-triphenylamine)phenoxy]ethoxy)tetrahydro-2H-pyrane
saturated solution of sodium chloride (500 mL), dried over 13 (1.80 g, 3.87 mmol, 1.0 eq). The crude product was puried
anhydrous sodium sulfate, ltered and concentrated under by a silica gel column chromatography (CH2Cl2) to a white solid
reduced pressure. The crude product was puried by a silica gel (1.29 g, 56%). m.p.: < 50 ꢃC; 1H NMR (400 MHz, CDCl3): d (ppm)
column chromatography (CH2Cl2) to give a colorless oil (3.18 g, ¼ 7.52 (d, J ¼ 8.7 Hz, 2H), 7.48 (d, J ¼ 8.2 Hz, 2H), 7.38 (d, J ¼ 9.2
99%). 1H NMR (400 MHz, CDCl3): d (ppm) ¼ 7.54 (d, J ¼ 9.2 Hz, Hz, 4H), 7.12 (d, J ¼ 8.2 Hz, 2H), 7.04 (d, J ¼ 8.7 Hz, 2H), 7.00 (d,
2H); 6.71 (d, J ¼ 8.7 Hz, 2H); 4.69 (t, J ¼ 3.4 Hz, 1H); 4.12–3.52 J ¼ 9.2 Hz, 4H), 4.78 (t, J ¼ 3.7 Hz, 1H), 4.24–3.58 (m, 6H), 1.92–
(m, 6H); 1.85–1.52 (m, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) 1.60 (m, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 158.3,
¼ 158.9, 138.3, 117.3, 99.2, 83.3, 67.7, 65.8, 62.4, 30.6, 25.5, 19.5; 146.4, 145.5, 132.9, 132.3, 127.63, 127.60, 125.4, 124.7, 115.5,
IR (cmꢀ1): 2939, 2871, 1586, 1573, 1484, 1452, 1282, 1242, 1200, 115.0, 98.9, 67.5, 65.8, 62.1, 30.5, 25.4, 19.4; IR (cmꢀ1): 2941,
1138, 1124, 1077, 1032, 1020, 985, 871, 815.
1607, 1579, 1484, 1455, 1313, 1284, 1268, 1248, 1201, 1176,
2-[40-(400-Triphenylamine)phenylethoxy]tetrahydro-2H-pyran 1125, 1071, 1035, 1007, 988, 819.
(12). The procedure B was applied using 2-(40-bromophenyle-
thoxy)tetrahydro-2H-pyran 9 (889 mg, 3.12 mmol, 1.1 eq) and 4- 200-yloxy)ethyl]biphenyl)amine (16). The procedure B was applied
(N,N-diphenylamino)phenylboronic acid (800 mg, 2.77 mmol, using
N,N-Di-(4-methoxy-10,100-biphenyl)-N-(4-[20-(tetrahydro-2H-pyran-
2-[20-(400-[4000-N,N-di-(40000-bromophenyl)aniline]phenyl)
1.0 eq). The crude product was puried by a silica gel column ethoxy]tetrahydro-2H-pyrane 14 (402 mg, 0.662 mmol, 1.0 eq)
chromatography (petroleum ether/CH2Cl2: 2/8 to CH2Cl2) to and 4-methoxyphenylboronic acid (245 mg, 1.61 mmol, 2.4 eq).
1
give a colorless oil (1.05 g, 84%). H NMR (400 MHz, CDCl3): d The crude product was puried by a silica gel column chro-
(ppm) ¼ 7.49 (d, J ¼ 8.2 Hz, 2H), 7.46 (d, J ¼ 8.7 Hz, 2H), 7.30– matography (petroleum ether/CH2Cl2: 6/4 to CH2Cl2) to give a
1
7.24 (m, 6H), 7.13 (m, 6H), 7.03 (dd, J ¼ 7.3, 7.3 Hz, 2H), 4.62 (t, white solid (380 mg, 87%). m.p.: 126 ꢃC; H NMR (400 MHz,
J ¼ 3.4 Hz, 1H), 4.00–3.48 (m, 4H), 2.95 (t, J ¼ 7.3 Hz, 2H), 1.83– CDCl3): d (ppm) ¼ 7.55–7.47 (m, 14H), 7.31 (d, J ¼ 8.2 Hz, 2H),
1.51 (m, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 147.9, 7.21 (d, J ¼ 8.7 Hz, 4H), 6.98 (d, J ¼ 8.7 Hz, 4H), 4.64 (t, J ¼ 3.5
147.1, 138.7, 137.9, 135.2, 129.5, 129.4, 127.8, 126.7, 124.5, Hz, 1H), 3.86 (s, 6H), 4.02–3.50 (m, 4H), 2.97 (t, J ¼ 7.1 Hz, 2H),
124.1, 123.0, 98.9, 68.4, 62.4, 36.1, 30.8, 25.6, 19.7; IR (cmꢀ1): 1.90–1.52 (m, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 158.9,
3029, 2940, 1591, 1492, 1325, 1276, 1135, 1120, 1077, 1030, 972, 146.9, 146.4, 138.6, 137.9, 135.3, 135.3, 133.3, 129.5, 127.8,
870, 839, 816.
2-(20-[400-(4000-Triphenylamine)phenoxy]ethoxy)tetrahydro-2H- 25.6, 19.6; IR (cmꢀ1): 2919, 1601, 1494, 1247, 1177, 1040, 818.
pyrane (13). The procedure B was applied using 2-[20-(400-iodo- N-(4-Bromophenyl)-N-(4-methoxy-10,100-biphenyl)-N-(4-[20-
127.5, 126.6, 124.6, 124.3, 114.3, 98.9, 68.4, 62.4, 55.4, 36.1, 30.8,
phenoxy)ethoxy]tetrahydro-2H-pyrane 11 (1.67 g, 4.79 mmol, 1.1 (tetrahydro-2H-pyran-200-yloxy)ethoxy]biphenyl)amine (17)
eq) and 4-(N,N-diphenylamino)phenylboronic acid (1.26 g, 4.35 and N,N-di-(4-methoxy-10,100-biphenyl)-N-(4-[20-(tetrahydro-
mmol, 1.0 eq). The crude product was puried by a silica gel 2H-pyran-200-yloxy)ethoxy]biphenyl)amine (18). The proce-
column chromatography (petroleum ether/CH2Cl2: 7/3 to dure B was applied using 2-[20-(400-[4000-N,N-di-(40000-bromophenyl)
1
CH2Cl2) to give a white solid (1.84 g, 91%). m.p.: < 50 ꢃC; H aniline]phenoxy)ethoxy]tetrahydro-2H-pyrane 15 (510 mg, 0.818
NMR (400 MHz, CDCl3): d (ppm) ¼ 7.51 (d, J ¼ 8.7 Hz, 2H), 7.45 mmol, 1.0 eq) and 4-methoxyphenylboronic acid (279 mg, 1.84
(d, J ¼ 8.7 Hz, 2H), 7.28 (dd, J ¼ 8.7, 7.3 Hz, 4H), 7.15 (m, 6H), mmol, 2.2 eq). The crude product was puried by a silica gel
7.05–7.00 (m, 4H), 4.75 (t, J ¼ 3.7 Hz, 1H), 4.23–3.52 (m, 6H), column chromatography (cyclohexane/AcOEt: 1/9) to give two
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white solids 17 (241 mg, 45%) and 18 (194 mg, 21%). Properties
of 17: m.p.: < 50 ꢃC; 1H NMR (400 MHz, CDCl3): d (ppm) ¼ 7.59
(d, J ¼ 8.7 Hz, 2H), 7.58 (d, J ¼ 8.7 Hz, 2H), 7.54 (d, J ¼ 8.7 Hz,
2H), 7.53 (d, J ¼ 8.7 Hz, 2H), 7.43 (d, J ¼ 8.7 Hz, 2H), 7.22 (d, J ¼
8.2 Hz, 4H), 7.10 (d, J ¼ 8.7 Hz, 2H), 7.08 (d, J ¼ 8.7 Hz, 2H), 7.05
(d, J ¼ 8.7 Hz, 2H), 4.84 (t, J ¼ 3.4 Hz, 2H), 4.29–3.62 (m, 6H),
3.91 (s, 3H), 2.00–1.63 (m, 6H); 13C NMR (100 MHz, CDCl3): d
(ppm) ¼ 158.9, 158.3, 146.8, 146.5, 145.9, 135.6, 133.1, 133.0,
132.2, 127.7, 127.6, 127.6, 127.5, 125.2, 124.6, 124.3, 115.0,
6 C. Quinton, V. Alain-Rizzo, C. Dumas-Verdes, F. Miomandre,
G. Clavier and P. Audebert, Chem.–Eur. J., 2015, 21, 2230–
2240.
7 C. Quinton, V. Alain-Rizzo, C. Dumas-Verdes, F. Miomandre,
G. Clavier and P. Audebert, RSC Adv., 2014, 4, 34332–34342.
8 Y. Kim, E. Kim, G. Clavier and P. Audebert, Chem. Commun.,
2006, 3612–3614.
9 Y. Kim, J. Do, E. Kim, G. Clavier, L. Galmiche and
P. Audebert, J. Electroanal. Chem., 2009, 632, 201.
´
114.9, 114.2, 99.0, 67.5, 65.9, 62.1, 55.3, 30.5, 25.5, 19.4; IR 10 F. Miomandre, E. Lepicier, S. Munteanu, O. Galangau,
(cmꢀ1): 1493, 1483, 1313, 1274, 1268, 1248, 1071, 1034, 847, 823,
J. F. Audibert, R. Meallet-Renault, P. Audebert and
R. B. Pansu, ACS Appl. Mater. Interfaces, 2011, 3, 690–696.
´
817. Properties of 18: m.p.: < 50 ꢃC; 1H NMR (400 MHz, CDCl3): d
´
(ppm) ¼ 7.53 (d, J ¼ 8.7 Hz, 4H), 7.52 (d, J ¼ 8.7 Hz, 2H), 7.47 (m, 11 C. Dumas-Verdes, F. Miomandre, E. Lepicier, O. Galangau,
´
6H), 7.20 (m, 6H), 7.00 (d, J ¼ 8.7 Hz, 2H), 6.97 (d, J ¼ 8.7 Hz,
4H), 4.74 (t, J ¼ 3.7 Hz, 1H), 4.22–3.54 (m, 6H), 3.85 (s, 6H), 1.87–
T. T. Vu, G. Clavier, R. Meallet-Renault and P. Audebert,
Eur. J. Org. Chem., 2010, 2525–2535.
1.53 (m, 6H); 13C NMR (100 MHz, CDCl3): d (ppm) ¼ 158.9, 12 A. C. Benniston, G. Copley, K. J. Elliott, R. W. Harrington and
158.3, 146.5, 135.2, 133.4, 133.3, 127.8, 127.7, 127.5, 124.5,
W. Clegg, Eur. J. Org. Chem., 2008, 2705–2713.
115.1, 114.3, 99.1, 67.6, 65.9, 62.3, 55.4, 30.6, 25.5, 19.5; IR 13 C. Quinton, V. Alain-Rizzo, C. Dumas-Verdes, G. Clavier,
(cmꢀ1): 1602, 1493, 1281, 1246, 1176, 1039, 846, 835, 820.
F. Miomandre and P. Audebert, Eur. J. Org. Chem., 2012,
1394–1403.
N,N-Di-[400-(N0,N0-dimethyl)-10,100-biphenyl]-N-(400-(2-(tetrahydro-
2H-pyran-2-yloxy)ethoxy)-10,100-biphenyl)amine (19). The procedure 14 C. Quinton, V. Alain-Rizzo, C. Dumas-Verdes, F. Miomandre
B was applied using 2-[20-(400-[4000-N,N-di-(40000-bromophenyl)aniline]
phenoxy)ethoxy]tetrahydro-2H-pyrane 15 (510 mg, 0.818 mmol, 15 H. G. Zhang, X. T. Tao, K. S. Chen, C. X. Yuan, S. N. Yan and
1.0 eq) and 4-(N,N-dimethylamino)phenylboronic acid (297 mg, M. H. Jiang, Chin. Chem. Lett., 2011, 22, 647–650.
1.80 mmol, 2.2 eq). The crude product was puried by a silica gel 16 Z. Qing, P. Audebert, G. Clavier, F. Miomandre, J. Tang,
and P. Audebert, Electrochim. Acta, 2013, 110, 693–701.
´
column chromatography (cyclohexane/AcOEt: 1/9) to give a white
solid (81 mg, 14%). m.p.: < 50 C; H NMR (400 MHz, CDCl3): d
T. T. Vu and R. Meallet-Renault, J. Electroanal. Chem.,
2009, 632, 39.
1
ꢃ
´
(ppm) ¼ 7.52–7.47 (m, 12H), 7.22–7.19 (m, 6H), 7.00 (d, J ¼ 8.7 Hz, 17 Q. Zhou, P. Audebert, G. Clavier, R. Meallet-Renault,
2H), 6.82 (d, J ¼ 8.7 Hz, 4H), 4.75 (t, J ¼ 3.4 Hz, 1H), 4.20–3.86 (m,
F. Miomandre, Z. Shaukat, T.-T. Vu and J. Tang, J. Phys.
Chem. C, 2011, 115, 21899–21906.
6H), 3.00 (s, 12H), 1.67–1.45 (m, 6H); 13C NMR (100 MHz, CDCl3): d
(ppm) ¼ 158.2, 149.7, 146.7, 146.0, 135.7, 134.8, 133.6, 129.1, 18 E. Jullien-Macchi, V. Alain-Rizzo, C. Allain, C. Dumas-Verdes
127.7, 127.6, 127.4, 127.0, 124.6, 124.1, 115.1, 113.0, 99.1, 67.6, and P. Audebert, RSC Adv., 2014, 4, 34127–34133.
66.0, 62.3, 41.2, 30.6, 25.5, 19.5; IR (cmꢀ1): 1608, 1494, 1249, 1177, 19 A. J. Wain, I. Streeter, M. Thompson, N. Fietkau, L. Drouin,
989, 869.
A. J. Fairbanks and R. G. Compton, J. Phys. Chem. B, 2006,
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20 S. Barlow, C. Risko, S. A. Odom, S. Zheng, V. Coropceanu,
´
L. Beverina, J.-L. Bredas and S. R. Marder, J. Am. Chem.
Acknowledgements
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49738 | RSC Adv., 2015, 5, 49728–49738
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