Synthetic routes to fluorescent dyes exhibiting large stokes shifts

Article abstract of DOI:10.1021/jo301059u

Derivatives of isomeric 2-(hydroxytolyl)-4,6-dimethylamino-1,3,5-triazines have been synthesized in high yields in a controlled manner using a multistep reaction sequence. Iodination of either 2-(1′-hydroxy-6′-methylphen- 2′-yl)- or 2-(1′-hydroxy-4′-methylphen-2′-yl)-4,6- dimethylamino-1,3,5-triazine with ICl provides species differing in the positioning of the iodo group relative to the hydroxyl which readily undergo Suzuki, Sonogashira, and Heck reactions under Pd(0) catalysis. Thus, thienyl, bisthienyl, and 3,4-ethylenedioxythienyl groups have been directly grafted, while unsubstituted polycyclic aromatics such as pyrene and perylene have been linked via alkyne bridges, as have ethynyldifluoroborondipyrromethane (BODIPY) dyes prepared in situ. The presence of a hydrogen bond in the ground state involving the hydroxyl substituent has been established by proton NMR and several X-ray structure determinations. All of the new dyes with a simple substituent (phenyl, thienyl) exhibited a pronounced green fluorescence resulting from an intramolecular proton transfer in the excited state (ESIPT) which produces a large Stokes shift (>10 000 cm^-1). With other dyes, the fluorescence of the keto form responsible for the ESIPT process could be used as the input energy in efficient intramolecular energy transfer processes. Replacing perylene with pyrene allowed reversal of the direction of energy transfer from the polyaromatic module to the keto form.

Full text of DOI:10.1021/jo301059u

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pubs.acs.org/joc
Synthetic Routes to Fluorescent Dyes Exhibiting Large Stokes Shifts
Sandra Rihn,† Pascal Retailleau,‡ Antoinette De Nicola,† Gilles Ulrich,† and Raymond Ziessel†,*
†Laboratoire de Chimie Organique et Spectroscopies Avancee
Chimie, Polymeres, Materiaux de Strasbourg (ECPM), 25 rue Becquerel, 67087 Strasbourg, Cedex 02 France
‡Laboratoire de Crystallochimie, ICSN-CNRS, Bat
. 27-1 avenue de la Terrasse, 91198 Gif-sur-Yvette, Cedex, France
́ ́
s (LCOSA), UMR 7515 au CNRS, Universite de Strasbourg, Ecole de
̀
́
̂
S
* Supporting Information
ABSTRACT: Derivatives of isomeric 2-(hydroxytolyl)-4,6-dimethyla-
mino-1,3,5-triazines have been synthesized in high yields in a controlled
manner using a multistep reaction sequence. Iodination of either 2-(1′-
hydroxy-6′-methylphen-2′-yl)- or 2-(1′-hydroxy-4′-methylphen-2′-yl)-
4,6-dimethylamino-1,3,5-triazine with ICl provides species differing in
the positioning of the iodo group relative to the hydroxyl which readily
undergo Suzuki, Sonogashira, and Heck reactions under Pd(0) catalysis.
Thus, thienyl, bisthienyl, and 3,4-ethylenedioxythienyl groups have been directly grafted, while unsubstituted polycyclic aromatics
such as pyrene and perylene have been linked via alkyne bridges, as have ethynyldifluoroborondipyrromethane (BODIPY) dyes
prepared in situ. The presence of a hydrogen bond in the ground state involving the hydroxyl substituent has been established by
proton NMR and several X-ray structure determinations. All of the new dyes with a simple substituent (phenyl, thienyl) exhibited
a pronounced green fluorescence resulting from an intramolecular proton transfer in the excited state (ESIPT) which produces a
large Stokes shift (>10 000 cm−1). With other dyes, the fluorescence of the keto form responsible for the ESIPT process could be
used as the input energy in efficient intramolecular energy transfer processes. Replacing perylene with pyrene allowed reversal of
the direction of energy transfer from the polyaromatic module to the keto form.
in the excited state (ESIPT process). Such dyes have become
well-known since the discovery of this mechanism in
methylsalicylate and related derivatives.10,11 They include o-
hydroxybenzophenones,12 o-hydroxyphenylbenzotriazoles,13 o-
hydroxyphenylbenzoxazoles,14 o-hydroxyphenylbenzothia-
zole,15 and some more sophisticated species,16 and they have
found application as UV stabilizers in polymers and sun
creams.12b
The anomalous emissions with large Stokes shifts displayed
in solution and the solid-state spectra of 6-(2-hydroxy-5-
methylphenyl)-1,3,5-triazine17 attracted our attention to them
as a potential platform for chemical transformations on the
phenyl residue aimed at (i) shifting the emissive properties into
the red; (ii) using the emission of the keto form (obtained by
the ESIPT process), as input energy in more sophisticated
multimodule systems; (iii) caging the photoluminescence by
protective residues; and finally (iv) tuning the optical properties
by changing the local environment of the dye (hydrophilic
versus hydrophobic).
INTRODUCTION
■
The ever-increasing interest in fluorescent probes has propelled
numerous research programs aimed at the discovery of new
dyes displaying high photostability and emission wavelength
tunability.1,2 After years of intense interdisciplinary research,
some basic rules have become clear for designing an effective
fluorescence probe suited to applications in chemistry and
biology. First, the dyes should possess large absorption cross
sections and high fluorescence quantum yields. Second, it
should be possible to tailor the probes at will in order to tune
the spectroscopic properties and to use them in multiplexing
experiments for tracking several targets.3,4 Third, the energy
offset between the dye and the medium of use should be well-
controlled to avoid nonradiative deactivation channels. Finally,
the dyes should have large Stokes shifts to provide high
resolution and low detection limits. These shifts reflect the
reorganization energy between the ground and excited state
and are quite difficult to manipulate with singlet excited states.5
One elegant recent solution was that of linking the dye (e.g., a
difluoroboron dipyrromethene, BODIPY) with modules
capable of intramolecular energy transfer (IMET).6 Under
these conditions, very large Stokes shifts (>10 000 cm−1) result
with anthracene-, pyrene-, and perylene-linked dyads or tryads.7
A cascade energy transfer event is the result of favorable
spectral overlap between the energy of the donor (e.g., pyrene)
and the energy of the acceptor (e.g., BODIPY),8 and in some
specific cases, through-bond energy transfer has also been
claimed.9
Access to 2,4,6-trifunctionalized 1,3,5-triazines is facile due to
the well-known ease of displacement of the chloride atoms in
cyanuric chloride by various nucleophiles in the presence of a
base.18 The substitution pattern is controlled mostly by the
temperature and the kinetics but also depends on the structure
of the nucleophile. The fact that with N-nucleophiles
symmetrical and unsymmetrical mono-, di-, and trisubstituted
Another way to promote large Stokes shifts is to engineer
molecules in which intramolecular proton transfer is promoted
Received: May 31, 2012
© XXXX American Chemical Society
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1,3,5-triazines can be easily prepared also opens up additional
synthetic possibilities.19
a very strong hydrogen bond20 was apparent from the chemical
shift of the phenolic proton at δ 14.4 and 14.0, respectively, in
neutral CDCl3.
Our present objective was to prepare 2-(hydroxy(methyl)-
phenyl)-4,6-dimethylamino-1,3,5-triazine derivatives function-
alized on the phenyl ring with various electron-rich modules so
as to enable tuning of their fluorescence properties. In
particular, we targeted the synthesis of two regioisomers of
each in order to determine the influence of the substituents on
proton transfer in the excited state (Chart 1).
Iodination of compound 3 using a solution of iodine
monochloride in methanol led to introduction of an iodo group
exclusively in the 4′ position of the phenyl ring as shown in
structure 7. For this compound, the phenyl protons resonate as
4
doublets at δ 8.48 and 7.50 with a JH−H coupling constant of
ca. 2.4 Hz. The X-ray structures of the functionalized
derivatives 8 confirmed the regioselectivity of the iodination
reaction (vide infra). The iodo derivatives were then submitted
to different Pd-catalyzed cross-coupling reactions (Suzuki,
Sonogashira, Heck) in order to extend the aromatic
functionality of the phenyltriazine compounds and, thereafter,
compare their photophysical properties (Scheme 2). Initially,
comparison was made of aryl derivatives with vinyl or acetylene
tethers with those having an aryl unit directly linked to the
phenyl core. Suzuki cross-coupling reaction with [Pd(PPh3)4]
as the catalyst precursor and K2CO3 as base was used to insert
different thienyl units (Scheme 2).21
Chart 1
Styrene was used in a Heck coupling using Pd(II) and
K2CO3 in benzene/DMF to afford compound 11.22 The Z-
conformation of the double bond was confirmed by the 16.9 Hz
proton−proton coupling constant. A Sonogashira cross-
coupling reaction [Pd(PPh3)4] catalyst, triethylamine as base
was used to insert a tolylacetylene residue. 4,4-Difluoro-
1,3,5,7,8-pentamethyl-2-iodo-4-bora-3a,4a-diaza-s-indacene
(BODIPY)23 was also linked to compound 7 via a one-pot
synthetic protocol. The instability of the corresponding
BODIPY-CCH under the conditions used forced us to
produce this intermediate in situ by (i) cross-coupling
trimethylsilyl acetylene to the iodo-BODIPY derivative and
then (ii) removing the TMS group with 1,8-diazabicyclo[5.4.0]-
undec-7-ene (DBU) in the presence of substoichiometric
amounts of water (40 mol %)24 and finally (iii) cross-linking
the resultant and nonisolated alkyne derivative to compound 7
to produce the target dyes 14 in acceptable yields.
Iodination of compound 6 was realized under the same
conditions using a solution of iodine monochloride in methanol
and led to introduction of an iodo group exclusively in the 6′
positions of the phenyl ring as shown in structure 17. For this
isomer, the phenyl protons resonate as doublets at δ 8.16 and
7.68 ppm with a 4JH−H coupling constant of ca. 2.0 Hz. The X-
ray structures of the functionalized derivatives 18 confirmed the
RESULTS AND DISCUSSION
■
The molecules of interest were prepared according to Scheme
1. Five steps are required to produce the pivotal compounds 3
and 6 in good yields. The sequence includes the protection of
the phenolic hydroxyl group of o- and p-cresol by
methoxymethyl chloride (MOMCl), using sodium hydride in
dimethylformamide to afford the substitution products 1 and 4
in quantitative yields. The protected phenols were then treated
with n-butyllithium in tetrahydrofuran at −78 °C to generate
the 2-lithio-aromatics. These were reacted with 1 equiv of
cyanuric chloride to give the monoaryl derivative and the
remaining chloro substituents then displaced by reaction with
dimethylamine (40 wt % in water) to produce compounds 2
and 5 in fair yields. Finally, removal of the MOM groups in acid
gave the desired compounds 3 and 6 (Scheme 1). In both cases,
Scheme 1. Preparation of the Triazine Starting Materials 3 and 6
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Scheme 2. Preparation of the para-Substituted Derivatives
regioselectivity of the iodination reaction (vide infra). This iodo
derivative was then submitted to different Pd-catalyzed cross-
coupling reactions (Suzuki, Sonogashira) in order to extend the
aromatic functionality of the phenyltriazine compounds and,
thereafter, compare their photophysical properties with the
other isomers described in Scheme 2. BODIPY was also linked
to isomer 17 via a similar one-pot synthetic protocol described
above for compound 14, involving the in situ preparation of
ethynyl-BODIPY derivative following a controlled cross-
coupling reaction with 17 in the presence of low valent
palladium(0) to produce the target dye 20 in acceptable yields
(Scheme 3).
X-ray Structure Determinations. The structures of the
isomers 8 and 18 provide an indication of the consequences of
the differences in location of a relatively small (thienyl)
substituent on the properties of the molecule in the solid state.
In both, it is apparent that the H-bond between the hydroxyl
group and a triazine-N25 plays an important role in maintaining
the planarity of the hydroxyphenyltriazine core (Figures 1 and
2).
deviation from an overall planar conformation (Figure 3). The
molecules 8 and 18 have a thienyl ring flip disorder, the
thiophene ring being disordered over two conformations about
the C5−C1 (C15, respectively) bond with a major−minor ratio
refined to values of 0.675(4):0.325(4) (0.515(3):0.485(3),
respectively). Compound 13 (Figure 3) also displays disorder
of one of the two alkyl chains over two sets of positions with
occupancies refined to 0.661(6) and 0.339(6) for the major and
minor conformations, respectively.
Although all three compounds have an overall conformation
which is close to planar, only the lattice of 8 shows a layered
structure with sheets parallel to the (20−1) plane having a
mean separation of 3.4 Å and centroid−centroid distance
between parallel triazine and adjacent rings (a triazine at
position 1−x, 2−y, 1−z and the phenyl at position −x, 2−y, 1−
z) along the a direction of 3.76 Å (Figure 4).
Within a layer in which molecules are separated by normal
van der Waals interactions, those which are not related by an
inversion center assemble preferentially into strips running
along [001] through formation of C−H···O hydrogen bonds
(H···O 2.3 Å; CHO 163.7°) (Figure 5).
The dihedral angle between the ethynylaniline phenyl ring
and the triazine unit of compound 13 is 26.52(7)°, a significant
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Scheme 3. Preparation of the ortho-Substituted Derivatives
Figure 2. ORTEP view (30% probability ellipsoids) of the molecular
unit found in the crystal lattice of 18. Dashed lines represent a minor
conformation of disordered atoms.
thiophene rings. In the case of 13, the inversion-related
molecules are segregated into undulating stripes running along
the [101] direction and stacking along the b direction with a
relative orientation of 35° between adjacent molecules (Figure
7). Interestingly, π−π stacking interactions mainly involve two
phenyl rings related by a center of inversion with a centroid
distance of 3.72 Å.
Optical Properties. The principal spectroscopic data
relevant to the present discussion are given in Table 1, and
typical examples are given in Figures 8−10. Generally, all dyes
exhibit absorption patterns typical for substituted 1,3,5-triazine
derivatives with an unstructured absorption band in the 320−
400 nm range depending on the substitution patterns and more
intense π−π* absorption at about 260 nm characteristic of the
phenyl fragments.25 Additional absorption transitions are found
as expected by grafting BODIPY (λabs 529 nm), pyrene (λabs
392 nm), or perylene (λabs 472 nm) modules. Interestingly, in
most cases, by irradiation in the triazine absorption around 350
nm, we did not observe the fluorescence expected for a classical
organic dye (such as emission profiles which mirror the
absorption, weak Stokes shift, etc.).5a Instead, we observed only
a green emission with a maximum lying in the 490−550 nm
range, with a large Stokes shift of about 10 000 cm−1 or 170 nm
(Figures 8−10).
This green fluorescence with large Stokes shifts is assigned to
that of the species resulting from intramolecular proton transfer
(excited keto form, S1′*) of the triazine derivatives (Chart
2).16a,26 In all present cases, the normal fluorescence of the
excited enol form (S1*) was not observed. This indicates that
either the lifetime of the fluorescent state S1 (excited enol
form) was extremely short (<10−12 s−1) or that a strong
intramolecular hydrogen bond was involved in the ground state
of the starting material. This has clearly been observed by NMR
spectroscopy in the severe deshielding of the phenolic signal
(see above).20 This shows that with the present 1,3,5-triazine
derivatives there is no hydrogen bond broken form (open-ring
conformer) in contrast to those of other aromatic compounds
such as salicylates giving ESIPT systems.11b
Figure 1. ORTEP view (30% probability ellipsoids) of the molecular
unit found in the crystal lattice of 8. Dashed lines represent a minor
conformation of disordered atoms.
The structure 18 features a herringbone packing motif
evident in a projection along the c axis with a dihedral angle of
70.1° between inverted molecules and those generated by the
mirror glide or helicoidal two-fold axis (Figure 6).
This arrangement results from π−π stacking interactions,
slightly offset and with centroid separation of 3.56 Å between
molecules at general position and those at 3−x, 1−y, 2−z, and
by triazine methyl hydrogen interactions with phenyl or
The fluorescence decay is monoexponential in all cases, and
the lifetime is on the nanosecond time scale (Table 1). The
corrected excitation spectrum matches well with the absorption
spectrum over the entire spectral window. In addition, the
fluorescence quantum yields and the excited-state lifetime
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Figure 3. ORTEP view (30% probability ellipsoids) of the molecular unit found in the crystal lattice of 13. Dashed lines represent a minor
conformation of disordered atoms.
Figure 4. Packing of molecules 8 in layers viewed down the c direction.
Figure 5. Packing of molecules 8 along the a direction. Molecules at general position (gray) and those related by an inversion center (gold).
recorded for the new dyes are independent of excitation
wavelength.
isomers, no effect was observed with thienyl compounds 8 and
18 and only a weak hypsochromic shift (5 nm) in absorption
was found for the 3,4-ethylenedioxythienyl (EDOT)-substi-
tuted compounds 9 and 19.
However, within a given isomer series, noticeable differences
were observed. Replacing an iodo group by a thienyl unit causes
25 and 38 nm bathochromic shifts, respectively, in the
The nature of the isomer has a relatively minor influence on
the energy of the low energy absorption band. A weak 8 nm
bathochromic shift was found in the absorption and emission
spectra of the para-isomer 3 with respect to the ortho-isomer 6
(for unsubstituted derivatives). In comparing both substituted
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a
Table 1. Selected Spectroscopic Data for the New Dyes
c
c
kr
(108
s−1
knr
(108
s−1
λabs
dyes (nm) cm−1
ε (M−1
λem
ΔSS
τF
Φ
Fb
)
(nm) (cm−1
)
(ns) (%)
)
)
3
6
319
327
332
357
360
355
316
300
341
325
529
350
392
472
333
356
355
532
350
7870
489
497
492
530
546
552
536
510
10900
4.5
5.3
1.1
4.7
4.1
1.8
3.4
5.8
28
30
7
0.6
0.6
8.7
0.5
0.4
0.3
0.3
0.4
1.6
1.3
0.5
1.6
2.0
5.4
2.7
1.3
7550
6060
10500
9800
7
8
5560
9100
25
18
5
9
4500
9500
10
11
12
43600
39500
31600
5600
10100
13000
9700
9
23
13
14
47000
52000
10100
36700
50500
9030
533
600
12000
2200
4.9
2.0
21
10
0.4
0.5
1.6
4.4
Figure 6. Packing of molecules 18 along the c axis. Molecules at
general position (gray), related by a center of inversion (gold), by a 21
axis (green), by a glide mirror c (magenta).
15
16
17
18
19
20
512
485
499
551
558
586
6000
570
4.5
2.0
1.2
2.5
2.3
1.3
46
46
6
0.1
2.3
0.5
0.5
0.5
1.2
1.2
2.8
7.8
3.5
3.9
6.5
absorption and emission spectra (Figure 9). Increasing the
electronic density by using EDOT had little effect on the
optical properties, whereas grafting of a bisthienyl unit
(compound 10) had detrimental effects on both the wave-
lengths of the absorption and emission and also on the
quantum yield (Figure 9). The increase of the nonradiative rate
for 10 may be due to the flexibility of the bisthienyl unit. Free
rotation along the C−C linkage favors nonradiative deactiva-
tion channels.
The linking of a tolyl moiety through an ethynyl bond
provided a greater bathochromic shift and a higher quantum
yield than with an ethenyl bond (λabs 341 nm, ϕF 23% for 12
compared to λabs 316 nm, ϕF 9% for 11, Figure 10). Switching
from a methyl group to a dibutylamino function had little effect
on the ϕF but induced a hypsochromic shift of 16 nm (compare
dyes 12 and 13, Table 1). The dibutylamino-functionalized
1,3,5-triazine is an interesting case because the spectroscopic
properties were sensitive to the environment and, in particular,
to acidic conditions. By spiking the solution with anhydrous
HCl vapor, the absorption and emission bands of dye 13 were
hypsochromically shifted by 14 and 50 nm, respectively (Figure
11). In situ deprotonation of the dibutylamino fragment using
triethylamine restored the initial absorption and emission
10100
9900
10300
1700
9170
12
11
16
7650
57000
14600
a
Measured in dichloromethane at rt except for dyes 14 and 20, which
b
were measured in toluene to limit aggregation. Using Rhodamine 6G
as reference, Φ = 0.78 in water,27 λex = 488 nm. Calculated using the
c
following equations: kr = ΦF/τF, knr = (1 − ΦF)/τF, assuming that the
emitting state is produced with unit quantum efficiency.
spectrum, proving the excellent stability of dye 13 under acidic,
neutral, and basic conditions. Note that the excitation spectra
perfectly match the absorption spectra in both situations.
We next investigated the spectroscopy of the dyads, in
particular, the BODIPY-linked 1,3,5-triazine (Figure 12). As
would be expected based on literature data,28 the major
absorption at low energy was the BODIPY-centered S0→S1
transition. At higher energy, the main absorption bands of the
substituted 1,3,5-triazine were seen at 348 and 364 nm, and the
structureless absorption at about 380 nm was assigned in the
light of previous data to the S0→S2 transition of the BODIPY
subunit.29 By excitation into the BODIPY absorption band at
Figure 7. Packing of molecules 13 along the b direction. Molecules at general position (gray), related by a center of inversion (gold), by a 21 axis
(green), by a glide mirror c (magenta).
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Figure 9. Absorption, emission, and excitation spectra of dyes 7, 8, 9,
and 10. Absorption (blue line for 7, red for 8, yellow for 9, and green
for 10), emission (purple for 7, black for 8, brown for 9, and pink for
10), and excitation (dashed blue line for 7, red for 8, yellow for 9, and
green for 10). For absorption, [c] ∼ 2 × 10−5 M for 7, 8, and 9, [c] ∼
1.3 × 10−5 M for 10; for emission, [c] ∼ 2 × 10−6 M for 7, 8, and 9
and [c] ∼ 1.3 × 10−6 M for 10 (λexc = 310 nm for 7, 350 nm for 8 and
9, 300 nm for 10); for excitation, [c] ∼ 2 × 10−6 M for 7, 8, and 9 and
[c] ∼ 1.3 × 10−6 M for 10 (λem = 450 nm for 7 and 8 and 500 nm for
9 and 10) in CH2Cl2 at rt .
Figure 8. Absorption, emission, and excitation spectra of dyes 7 and 8.
Absorption (blue line for 7, red for 8), emission (green for 7, yellow
for 8), and excitation (dashed blue line for 7, red for 8). For
absorption, [c] ∼2 × 10−5 M for both dyes; for emission, [c] ∼2 ×
10−6 M for both dyes (λexc = 310 nm for 7 and 350 nm for 8); for
excitation, [c] ∼2 × 10−6 M for both dyes (λexc = 450 nm for 7 and 8)
in CH2Cl2 at rt .
Chart 2. Schematic Representation of the Energy-State
Diagram for the Ground and Excited State of Triazine
Derivatives during the Intramolecular Proton Transfer
Processes: S0,S′0 and S1,S′1 Denote, Respectively, the
Ground and Excited States
Figure 10. Absorption, emission, and excitation spectra of dyes 11 and
12. Absorption (blue line for 11, red for 12), emission (green for 11,
and yellow for 12), excitation (dashed blue line for 11, and red for 12).
For absorption, [c] ∼ 1.2 × 10−5 M for 11 and 1.8 × 10−5 M for 12;
for emission, [c] ∼ 1.2 × 10−6 M for 11 and 1.8 × 10−6 M for 12 (λexc
= 300 nm for both dyes); for excitation, [c] ∼ 1.2 × 10−6 M for 11 and
1.8 × 10−6 M for 12 (λem = 480 nm for 11 and 460 nm for 12) in
CH2Cl2 at rt .
(Figure 12 and Table 1). From a mechanistic viewpoint, this is
an interesting case because the emission of the keto form
strongly overlaps with the absorption of the BODIPY singlet,
and the hypothetical emission of the enol form should strongly
overlap with the absorption of the second excited state of the
BODIPY subunit. Keeping in mind that the excited state of the
enol form is very short and that of the keto form is on the
nanosecond time scale, we prefer the first hypothesis. These
results are in keeping with previous results obtained with 4-
alkyne-functionalized [2,2′-bipyridine]-3,3′-diol ESIPT dye
types.30
500 nm, intense emission of the BODIPY was detected.
Interestingly, the irradiation into the triazine fragment at 350
nm resulted exclusively in BODIPY emission with no residual
emission of the triazine ESIPT form (below 550 nm). This
interesting result indicates that almost quantitative energy
transfer from the ESIPT excited state to the BODIPY was
occurring and that the triazine module could be used as an
input energy device in more sophisticated systems. This result
also held true for the ortho-isomer triazine-BODIPY dyad, 20
It is instructive to take stock of the likely events that follow
selective excitation into pyrene or perylene residues in the
triazine dyads 15 and 16 (Figure 13). As would be expected
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Figure 13. Absorption, emission, and excitation spectra of dyes 15 and
16. Absorption (blue line for 15, red for 16), emission (blue for 15,
and red for 16), excitation (dashed blue line for 15, and red for 16).
For absorption, [c] ∼ 1 × 10−5 M for 15 and 9 × 10−6 M for 16; for
emission, [c] ∼ 1 × 10−6 M for 15 and 9 × 10−7 M for 20 (λexc = 340
nm for 15 and 430 nm for 16); for excitation, [c] ∼ 1 × 10−6 M for 15
and 9 × 10−7 M for 16 (λem = 450 nm for 15 and 500 nm for 16) in
CH2Cl2 at rt .
Figure 11. Absorption, emission, and excitation spectra of dye 13.
Absorption and emission (blue line), excitation (dashed line blue),
emission with addition of anhydrous HCl vapors (yellow line),
excitation with addition of anhydrous HCl vapors (dashed line
yellow), emission after addition of anhydrous HCl vapors then
triethylamine (green line) excitation after addition of anhydrous HCl
vapors then triethylamine (dashed green line). For absorption, [c] ∼
1.4 × 10−5 M; for emission, [c] ∼ 1.4 × 10−6 M (λexc = 300 nm); for
excitation, [c] ∼ 1.4 × 10−6 M for 11 and 1.8 × 10−6 M for 12 (λem
=
500 nm) in EtOH at rt .
substitution of the iodo function in 7 or 17 with, for example,
thienyl groups or by grafting electron-rich modules such as the
bisthienyl or perylene fragments (Figure 13). Switching from
pyrene to perylene (compound 16) induced a pronounced shift
of the main absorption of the polyaromatic moiety to lower
energies (about 450 nm) and reduced the spectral overlap
between the emission of the perylene and the absorption of the
triazine. As a major consequence, excitation in the perylene
subunit produced the characteristic structured emission of
perylene.31 This emission mirrored the absorption and is
characteristic of a singlet excited state having a excited-state
lifetime of 1.3 ns. By irradiation in the triazine absorption band
in compound 16, no emission of the keto form was found at
512 nm and the excited-state decay lifetime of the emission at
520 nm was monoexponential, excluding the presence of two
overlapping emissive species. In the case of the perylene-grafted
molecule 16 and contrary to the pyrene case 15, energy transfer
occurred from the keto form to the emissive state of perylene.
Furthermore, the corrected excitation spectrum matched well
with the absorption spectrum over the entire spectral window,
and it is clear that photons collected by the pyrene subunit in
the case of 15 and by the keto form of the triazine in the case of
16 were transferred quantitatively to the keto or perylene
modules, respectively, under these conditions (Figure 13). This
is interesting and has not been previously observed in related
BODIPY dyads or tryads.8
In short, we have succeeded in extending the scope of 2-
phenyl-functionalized 1,3,5-triazine platforms and have devel-
oped efficient routes to a variety of derivatives. Two series of
constitutional isomers have been prepared and their spectro-
scopic properties studied. It was clearly established based on
the chemical shift of the phenolic proton (>14.0 ppm) and
confirmed by several X-ray diffraction studies that a very strong
hydrogen bond favors the flat structure and a very efficient
proton transfer in the excited state (ESPIT) provides a green
fluorescence and a large Stokes shift. Absorption and emission
are tunable by changing the nature of the substituent over a
range of about 320 to 472 nm when comparing the
unsubstituted triazine to the perylene-functionalized dye. The
Figure 12. Absorption, emission, and excitation spectra of dyes 14 and
20. Absorption (blue line for 14, red for 20), emission (blue for 14,
and red for 20), excitation (dashed blue line for 14, and red for 20).
For absorption, [c] ∼ 1.5 × 10−5 M for 14 and 7.7 × 10−6 M for 20;
for emission, [c] ∼ 1.5 × 10−6 M for 14 and 7.7 × 10−6 M for 20 (λexc
= 500 nm for both dyes); for excitation, [c] ∼ 1.2 × 10−6 M for 11 and
1.8 × 10−6 M for 12 (λem = 630 nm for both dyes) in toluene at rt .
based on the results described above with the BODIPY
modules, the absorption spectrum of dyads 15 and 16 is almost
a linear combination of the absorption of the triazine, pyrene,
or perylene, respectively. The pyrene has a pronounced
absorption which is overlapping with the absorption of the
triazine. By irradiation in the pyrene band at ca. 400 nm, no
residual emission of the pyrene was observed and only emission
at 512 nm was triggered. This emission was assigned to the
emission of the keto form of the triazine for which a marked
ESIPT process is occurring (Chart 2). Interestingly, the
quantum yield was the highest determined within this series
of dyes (46%, Table 1). It is likely that the emission of the
pyrene overlaps with the absorption of the triazine. The
absorption of the latter is probably shifted bathochromically
due to the high electron density imported by the pyrene
moiety. Similar bathochromic shifts were observed by
H
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General Procedure 1 for the Synthesis of Hydroxyphenyl-
1,3,5-triazine-2,4-dimethylamine Compounds. To a solution of
the MOM-protected toluene derivatives in anhydrous THF was added
n-BuLi (1.1 equiv, 1.6 M solution in hexane) at −78 °C under argon.
The reaction mixture was allowed to warm to room temperature and
stirred for 2 h. The resulting solution was slowly added to a solution of
cyanuric chloride (1 equiv) in THF at −78 °C. The mixture was then
warmed to rt and stirred for another 18 h. A 40% aqueous solution of
dimethylamine (9 equiv) was added to the mixture and refluxed until
TLC analysis showed that all starting material had been consumed.
After being cooled to room temperature, the organic layer was
separated and the aqueous layer was extracted with AcOEt. The
combined organic phases were dried over MgSO4, and the solvents
were evaporated. The residue was then submitted to column
chromatography separation on silica gel with petroleum ether/ethyl
acetate (5:1) as eluant to give the desired compound in better than
50% yield.
General Procedure 2 for the Methoxymethylether Depro-
tection. Compound 2 or 5 was dissolved in a solution of CH2Cl2 (20
mL)/MeOH (20 mL)/EtOH (10 mL), and a solution of 6 M HCl was
slowly added. The solution was stirred 12 h at rt. The mixture was
poured into water (50 mL) and was extracted with CH2Cl2. The
combined CH2Cl2 solution was washed with a saturated solution of
NaHCO3 and dried over MgSO4. The residue was then submitted to
column chromatography separation on silica gel.
General Procedure 3 for the Hydroxyphenyl-s-triazine-2,4-
dimethylamine Iodinations. To a solution of hydroxyphenyl-1,3,5-
triazine-2,4-dimethylamine (1 equiv) in a 50/50 mixture of DMF/
MeOH was added dropwise a solution of ICl (1.5 equiv) in MeOH
(10 mL). The reaction mixture was then stirred at room temperature,
and the reaction progress was checked by TLC. After a period of time,
TLC indicated that all starting material had been consumed. The
reaction mixture was then diluted with CH2Cl2, washed with water,
and extracted with CH2Cl2. The organic layer was dried over MgSO4,
and the solvents were evaporated. The crude product was recrystal-
lized from EtOH/nonane to give white crystals.
General Procedure 4 for the Suzuki Cross-Coupling
Reaction. A Schlenk tube was charged with a solution of appropriate
iodo- and arylboronic acid or boronate derivatives in toluene. A
mineral base (K2CO3) was also added. The solution was degassed with
argon for 30 min, then [Pd(PPh4)3] was added. The mixture was
stirred at 60 °C until complete consumption of the starting material
(monitored by TLC). The solution was then extracted with CH2Cl2,
washed with water, dried over MgSO4, and evaporated under vacuum.
The residue was purified by column chromatography.
BODIPY modules extend the absorption to about 530 nm. In
the case of the polyaromatic modules, interesting energy
transfer pathways from the excited polycycles to the keto form
of the excited triazine-phenol core or to the polycycle have
been observed. All of these processes appear to be efficient and
fast keeping in mind the short excited-state lifetimes. Many
interesting features emerge from these studies, and solid-state
spectroscopy should help the design of light-emitting devices.
These multifunctional molecules not only are promising as
fluorophores but also provide a new prospect for dye
innovation. The synthetic protocols and methodology pave
the way for the design of more sophisticated scaffoldings in
which multicascade energy transfer process could be used to
concentrate photons to a large extent in order to promote
chemical transformations or charge separation. Work along
these lines is currently in progress.
EXPERIMENTAL SECTION
■
General Methods. All reactions were performed under a dry
atmosphere of argon using standard Schlenk tube techniques. All
chemicals were used as received from commercial sources without
further purification unless otherwise stated. CH2Cl2 was distilled from
P2O5 under an argon atmosphere. THF was distilled from sodium and
benzophenone under an argon atmosphere. Toluene was distilled from
sodium under an argon atmosphere. DMF was allowed to stand one
night on KOH pellets prior to being distilled. The 200, 300, 400 (1H)
and 50, 75, 100 MHz (13C) NMR spectra were recorded at room
temperature using perdeuterated solvents as internal standards: ‰
(H) in parts per million relative to residual protiated solvent; ‰ (C)
in parts per million relative to the solvent. Mass spectra were measured
with a ESI-MS mass spectrometer. Chromatographic purifications
were performed using 40−63 μm silica gel. TLC was performed on
silica gel plates coated with a fluorescent indicator.
Electronic absorption and emission spectra were measured under
ambient conditions using commercial instruments. Fluorescence
spectra were recorded with a spectrofluorimeter. Solvents for
spectroscopy were spectroscopic grade and were used as received
after checking for impurities. A wide variety of excitation wavelengths
were used, according to the species under investigation. Luminescence
lifetimes were measured on a spectrofluorimeter, using software with
time-correlated single photon mode coupled to a Stroboscopic system.
The excitation source was a laser diode (λ 310 nm). No filter was used
for the excitation. The instrument response function was determined
by using a light-scattering solution (LUDOX).
General Procedure 5 for the Sonogashira Cross-Coupling
Reactions Using [Pd(PPh3)4]. A Schlenk tube was charged with a
solution of appropriate iodo and ethynyl derivatives in a mixture of
benzene/triethylamine (5/1). The solution was degassed with argon
for 30 min, then [Pd(PPh3)4] (10 mol %) was added. The mixture was
stirred at 60 °C overnight. After being cooled, the solution was
extracted with CH2Cl2, washed with water, dried over MgSO4, and
evaporated under vacuum. The residue was purified by column
chromatography.
The following equation was used to determine the relative
fluorescence quantum yield:
OD
OD
I
n2
ref
Φ
= Φ
cmp
ref
nr2ef
I
ref
Here, I denotes the integral of the corrected emission spectrum, OD is
the optical density at the excitation wavelength, and η is the refractive
index of the medium. The reference fluorescence quantum yields were
measured relative to Rhodamine 6G and cresyl violet27 as standards.
Synthesis. All moisture-sensitive reactions were carried out under
dry argon by using Schlenk tube techniques. All reagents were used
directly as obtained commercially unless otherwise noted. o-Cresol, p-
cresol, cyanuric chloride, butyllithium solution, dimethylamine
solution 40 wt % in H2O, sodium hybride 60% dispersion in mineral
oil, 2,4-dimethylpyrrole, boron trifluoride etherate, copper(I) iodide,
ethynyltrimethylsilane, 3,4-ethylenedioxythiophene, iodine mono-
chloride, styrene, 1,8-diazabycyclo[4.5.0]undec-7-ene, diisopropyl-
amine, and 4-ethynyltoluene were purchased from different
commercial sources and used without further purification. [Pd-
(PPh3)4],32 [Pd(PPh3)2Cl2],33 3-ethynylperylene,34 1-ethynylpyrene,35
compounds 136 and 4,37 and 4,4-difluoro-1,3,5,7,8-pentamethyl-2-
iodo-4-bora-3a,4a-diaza-s-indacene23 were synthesized according to
the literature procedures.
2-Thielnylboronic Acid.38 A solution of thiophene (9.93 mL,
10.43 g, 0.124 mol) in dry THF (120 mL) cooled at −78 °C was
treated dropwise with n-BuLi (100 mL, 1.6 mol/L). The reaction
mixture was stirred at −78 °C for 30 min and then allowed to warm to
−20 °C slowly. This 2-thienyllithium was again cooled to −78 °C and
transferred by cannula into a solution of trisethylborate (28.1 mL,
24.08 g, 0.165 mol) in dry THF (80 mL) at −78 °C. The reaction
mixture was stirred at −78 °C for 1 h before warming to room
temperature. The mixture was then treated with 1 M aqueous HCl
(200 mL) and the organic layer separated. The aqueous layer was then
extracted with dichloromethane (5 × 120 mL), and the combined
organic layers were dried (MgSO4) and concentrated under reduced
pressure to afford a white solid. Recrystallized of the white solid from
water gave thiopheneboronic acid as a pure white solid (10.0 g, 63%):
mp 126 °C; 1H NMR (200 MHz, CDCl3) δ = 7.59 (dd, 2H, 3J = 18.4
I
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4
3
Hz, J = 4.0 Hz), 7.14 (t, 1H, J = 4.0 Hz), 6.55 (s, 2H); 13C NMR
9.80 mmol) and KOH (275 mg, 4.90 mmol). The mixture was stirred
for 1 h and filtered. The solvent was removed by rotary evaporation.
The residue was purified by chromatography on silica gel, eluting with
dichloromethane/petroleum ether (v/v 15/85) to give 222 mg (82%)
of 3-ethynylperylene as a yellow solid: 1H NMR (400 MHz, CDCl3) δ
(acetone, 75 MHz) δ = 140.7, 136.3, 130.4.
4,4,5,5-Tetramethyl-2-(2-thienyl)-1,3,2-dioxaborolane.39 To
a solution of 2-iodothiophene (210.0 mg, 1.00 mmol), copper iodine
(19.0 mg, 0.01 mmol), and sodium hybride (60.0 mg, 1.50 mmol) in
dry THF (4 mL) was added pinacolborane (192.0 mg, 1.50 mmol,
0.218 mL) via syringe under argon atmosphere. The resultant mixture
was stirred at room temperature until the iodoaryl disappeared as
monitored by TLC. After the reaction was quenched by adding 10 mL
of saturated NH4Cl, the mixture was extracted with ethyl acetate. The
combined organic layers were washed with brine and dried over
MgSO4. The solution was concentrated under vacuo, and the residue
was chromatographed eluting with a mixture of petroleum ether/ethyl
acetate (9:1) to give the desired compound as a white solid (182.8 mg,
87%): 1H NMR (200 MHz, CDCl3) δ = 7.66−7.63 (m, 2H), 7.19 (dd,
3
= 8.24−8.17 (m, 4H), 8.11 (d, 1H, J = 8.0 Hz), 7.72−7.68 (m, 3H),
7.57 (t, 1H, 3J = 8.0 Hz), 7.47 (td, 2H, 3J = 8.0, 4J = 1.7 Hz), 3.55 (s,
1H); 13C NMR (100 MHz, CDCl3) δ = 134.9, 134.5, 132.3, 131.8,
131.4, 130.8, 130.5, 128.5, 128.4, 128.1, 127.3, 126.6, 125.9, 121.0,
120.7, 119.4, 118.9, 82.8, 82.1.
Compound 2. Prepared according to general procedure 1: 2-
(methoxymethyl)toluene compound 1 (4 g, 25.1 mmol), dry THF
(150 mL), n-Buli (17.25 mL, 1.77 g), cyanuric chloride (4.63 g, 25.1
mmol) in dry THF (80 mL), dimethylamine (28.6 mL, 25.5 g).
Column chromatography on silica gel eluting with petroleum ether/
ethyl acetate (5:1) as eluant to give compound 2 as a white powder
(4.41 g, 55%): 1H NMR (200 MHz, CDCl3) δ = 7.66 (dd, 1H, 3J = 7.8
Hz, 4J = 1.8 Hz), 7.24 (d, 1H, 3J = 7.8 Hz), 7.06 (m, 1H), 5.00 (s, 2H),
3.47 (s, 3H), 3.19 (s, 12H), 2.38 (s, 3H); 13C NMR (CDCl3, 50 MHz)
δ = 171.8, 165.3, 154.7, 143.4, 132.4, 132.0, 129.4, 123.6, 100.5, 57.1,
36.1, 17.1; EI-MS, m/z (%) 317.1 (100). Anal. Calcd for C16H23N5O2:
C, 60.55; H, 7.30; N, 22.07. Found: C, 60.44; H, 6.97; N, 21.82.
Compound 3. Prepared according general procedure 3: compound
2 (1.0 g, 3.15 mmol), 6 M HCl (9 mL). Column chromatography on
silica gel eluting with CH2Cl2 to give compound 3 as a white solid
(787.5 mg, 91%): mp 161−162 °C; IR (ATR) ν in cm−1 2921 (w),
2865 (w), 1561 (s), 1514 (s), 1407 (s), 1393 (s), 1368 (s), 1209 (m),
3
3
1H, J = 3.1 Hz, J = 2.3 Hz), 1.35 (s, 12H).
4,4′,5,5′-Tetramethyl-1,3,2-dioxaboronic Ester of 3,4-Ethyl-
enedioxythiophene.40 A solution of 3,4-ethylenedioxythiophene
(1.33 g, 9.36 mmol) in dry THF (25 mL) was cooled to −78 °C under
argon, and 7.02 mL of n-BuLi solution (1.6 M, 11.2 mmol) was slowly
added. The mixture was stirred at 0 °C for 30 min and then recooled
to −78 °C. At this temperature, the reaction was treated with 2-
isopropoxy-4,4′,5,5′-tetramethyl-1,3,2-dioxaborolane (5.34 mL, 26.2
mmol), and the mixture was stirred for one night. The reaction was
poured into crushed ice/NH4Cl, and the product was then extracted
with Et2O (3 × 30 mL). After being dried over MgSO4, the solvent
was removed at reduced pressure. The white solid product was used
without further purification: 1H NMR (200 MHz, CDCl3) δ = 6.65 (s,
1H), 4.31 (m, 2H), 4.21 (m, 2H), 1.35 (s, 12H).
44
1
816 (s); H NMR (200 MHz, CDCl3) δ = 14.43 (s, 1H), 8.25 (dd,
1H, 3J = 7.8 Hz, 4J = 1.5 Hz), 7.24 (d, 1H, 3J = 8.8 Hz), 6.79 (t, 1H, 3J
= 7.8 Hz), 3.21 (s, 12H), 2.29 (s, 3H); 13C NMR (CDCl3, 50 MHz) δ
= 170.1, 163.6, 160.2, 134.0, 126.8, 126.1, 117.8, 117.7, 36.4, 16.0; EI-
MS, m/z (%) 274.2 (100). Anal. Calcd for C14H19N5O: C, 61.52; H,
7.01; N, 25.62. Found: C, 61.27; H, 6.64; N, 25.84.
4,4-Difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene
was synthesized according to a literature procedure41 and recovered as
1
orange needles: yield 44%; H NMR (300 MHz, CDCl3) δ = 6.05 (s,
2H), 2.58 (s, 3H), 2.52 (s, 6H), 2.41 (s, 6H); UV−vis (CH2Cl2) λ nm
(ε, M−1 cm−1) 496 (94000), 467 (sh, 23000), 422 (6400), 356 (6200).
4,4-Difluoro-1,3,5,7,8-pentamethyl-2-iodo-4-bora-3a,4a-diaza-s-in-
dacene was synthesized according to literature procedures42 and
recovered as orange needles: yield 66%; 1H NMR (CDCl3, 400 MHz)
δ = 6.12 (s, 1H), 2.60 (s, 6H), 2.53 (s, 3H), 2.45 (s, 3H), 2.42 (s, 3H);
13C NMR (CDCl3, 75 MHz) δ = 156.2, 143.2, 141.3, 140.9, 84.4, 19.6,
Compound 5. Prepared according to general procedure 1: 4-
(methoxymethyl)toluene compound 4 (2.5 g, 15.7 mmol), dry THF
(125 mL), n-Buli (11.0 mL, 1.11 g), cyanuric chloride (2.89 g, 15.7
mmol) in dry THF (50 mL), dimethylamine (17.9 mL, 15.9 g).
Column chromatography on silica gel eluting with petroleum ether/
ethyl acetate (5:1) as eluant to give compound 5 as a white powder
17.7, 17.2, 15.9, 14.7; 11B NMR (CDCl3, 128 MHz) δ = 3.55 (t, J =
1
1
4
(2.51 g, 50%): H NMR (200 MHz, CDCl3) δ = 7.53 (d, 1H, J =
7.84), 7.11 (m, 2H), 5.16 (s, 2H), 3.50 (s, 3H), 3.18 (s, 12H), 2.32 (s,
3H); 13C NMR (CDCl3, 75 MHz) δ = 171.5, 165.4, 153.5, 131.7,
131.4, 131.0, 130.3, 118.2, 96.4, 56.0, 36.2, 20.7; EI-MS, m/z (%)
318.1 (100). Anal. Calcd for C16H23N5O2: C, 60.55; H, 7.30; N, 22.07.
Found: C, 60.37; H, 7.09; N, 21.79.
32 Hz); UV−vis (CH2Cl2) λ (nm) (ε, M−1 cm−1) = 509 (90000), 478
(sh, 27000), 421 (7000), 367 (9000); IR (KBr, cm−1) 2963, 2923,
2853, 1782, 1547, 1528,1482, 1459, 1443, 1401, 1374, 1345, 1304,
1261, 1225, 1196, 1165, 1139, 1126, 1105, 1083, 1063, 1026, 975;
FAB+-MS m/z (nature of peak, relative intensity) 389.1 ([M+H]+,
100), 369.1 ([M−F]+, 15). Anal. Calcd for C14H16BF2IN2: C, 43.34; H,
4.16; N, 7.22. Found: C, 43.20; H, 3.92; N, 7.05.
Compound 6. Prepared according general procedure 3: compound
5 (4.41 g, 13.89 mmol), 6 N HCl (40 mL). Column chromatography
on silica gel eluting with CH2Cl2 to give compound 6 as a white solid
(2.73 g, 72%): mp 162−163 °C; IR (ATR) ν in cm−1 2921 (w), 2865
(w), 1561 (s), 1514 (s), 1407 (s), 1393 (s), 1368 (s), 1209 (m), 816
N,N-Dibutyl-4-ethynylaniline.43 A 25 mL round-bottom flask
equipped with a magnetic stir bar was charged with N,N-dibutyl-4-
((trimethylsilyl)ethynyl)aniline (160.0 mg, 0.530 mmol), KOH (35.7
mg, 0.637 mmol), THF (1.0 mL), MeOH (5.0 mL), and water (1.0
mL). The reaction mixture was stirred for 90 min at 60 °C, diluted
with Et2O, washed with H2O and brine, and dried over MgSO4. The
solvent was removed under reduced pressure, and the crude product
was used without further purification (116.9 mg, 96% yield, green oil):
1
3
(s); H NMR (200 MHz, CDCl3) δ = 14.0 (s, 1H), 8.15 (d, 1H, J =
1.9 Hz), 7.16 (dd, 1H, 3J = 7.2 Hz, 4J = 1.2 Hz), 6.86 (d, 1H, 3J = 8.3
Hz), 3.20 (s, 12H), 2.32 (s, 3H); 13C NMR (CDCl3, 50 MHz) δ =
170.0, 163.7, 159.7, 134.2, 129.0, 127.4, 118.1, 117.4, 36.4, 20.8; EI-
MS, m/z (%) 274.2 (100). Anal. Calcd for C14H19N5O: C, 61.52; H,
7.01; N, 25.62. Found: C, 61.38; H, 6.76; N, 25.35.
1H NMR (CDCl3, 200 MHz) 6.92 (ABsyst, 4H, J = 9.0 Hz, υ0δ =
3
157.5 Hz), 3.26 (t, 4H, 3J = 7.6 Hz), 2.96 (s, 1H), 1.56−1.28 (m, 8H),
Compound 7. Prepared according general procedure 3: compound
3 (650.0 mg, 2.38 mmol), ICl (579.1 mg, 3.57 mmol), MeOH (50
mL), DMF (50 mL). The crude product was recrystallized from
EtOH/nonane to give compound 7 as yellow powder (856.3 mg,
90%): mp 215−216 °C; IR (ATR) ν in cm−1 2916 (w), 2863 (w),
1589 (s), 1557 (s), 1513 (s), 1460 (m), 1434 (m), 1403 (s), 1388 (s),
1357 (m), 1205 (m), 1053 (m), 866 (s), 805 (s); 1H NMR (200 MHz,
CDCl3) δ = 14.55 (s, 1H), 8.49 (d, 1H, 3J = 2.4 Hz), 7.50 (d, 1H, 3J =
2.0 Hz), 3.20 (s, 12H), 2.23 (s, 3H); 13C NMR (CDCl3, 50 MHz) δ =
168.8, 163.4, 160.1, 141.9, 135.2, 129.1, 119.2, 79.4, 36.5, 16.7; EI-MS,
m/z (%) 400.0 (100). Anal. Calcd for C14H18IN5O: C, 42.12; H, 4.54;
N, 17.54. Found: C, 41.80; H, 4.77; N, 17.49.
3
0.95 (t, 6H, J = 7.3 Hz).
1-Ethynylpyrene. To a solution 3-(pyren-1-yl)prop-2-yn-1-ol
(400 mg, 1.56 mmol) in THF (30 mL) were added MnO2 (1.36 g,
15.62 mmol) and KOH (438 mg, 7.81 mmol). The mixture was stirred
for 1 h and filtered. The solvent was removed by rotary evaporation.
The residue was purified by chromatography on silica gel, eluting with
dichloromethane/petroleum ether (v/v 5/95) to give 297 mg (84%)
of 1-ethynylpyrene as a white solid: 1H NMR (200 MHz, CDCl3) δ =
8.60 (d, 1H, J = 9.0 Hz), 8.22−8.04 (m, 8 H), 3.63 (s, 1 H); 13C
3
NMR (50 MHz, CDCl3) δ = 132.5, 131.6, 131.1, 131.0, 130.2, 128.6,
128.4, 127.2,126.6, 126.3, 125.7, 125.3, 124.4, 82.8, 82.6.
3-Ethynylperylene. To a solution 3-(perylen-3-yl)prop-2-yn-1-ol
(300 mg, 0.98 mmol) in THF (50 mL) were added MnO2 (852 mg,
Compound 8. Prepared according to general procedure 4:
compound 7 (50.0 mg, 0.125 mmol), 2-thienylboronic acid (0.500
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mmol, 64.2 mg, 4 equiv), and aqueous K2CO3 (86.5 mg, 0.626 mmol,
5 equiv) in toluene (10 mL). Column chromatography on silica gel
eluting with petroleum ether/CH2Cl2 4:6 to 1:9 as eluant to give
compound 8 as a yellow powder (13.9 mg, 31%): mp 209−210 °C; IR
(ATR) ν in cm−1 3097 (w), 3058 (w), 2923 (m), 1613 (m), 1563 (s),
mL). Column chromatography on silica gel eluting with petroleum
ether/CH2Cl2 8:2 to 5:5 as eluant to give compound 12 as a pale
yellow powder (43.7 mg, 90%): mp 218−219 °C; IR (ATR) ν in cm−1
2924 (w), 2857 (w), 1612 (m), 1563 (s), 1511 (s), 1435 (m), 1390
1
(s), 1209 (m), 1055 (m), 810 (s); H NMR (200 MHz, CDCl3) δ =
1
8.41 (d, 1H, 3J = 2.2 Hz), 7.41 (d, 1H, 3J = 2.2 Hz), 7.28 (AB sys, 4H,
JAB = 7.9 Hz, υoδ = 56.1 Hz), 3.23 (s, 12H), 2.36 (s, 3H), 2.29 (s, 3H);
13C NMR (CDCl3, 50 MHz) δ = 169.4, 163.4, 160.6, 137.7, 136.8,
131.3, 130.4, 129.0, 126.6, 120.8, 117.8, 112.5, 89.4, 87.2, 36.4, 21.5,
15.9; EI-MS, m/z (%) 387.1 (100). Anal. Calcd for C23H25N5O: C,
71.29; H, 6.50; N, 18.07. Found: C, 70.92; H, 6.32; N, 17.80.
1510 (s), 1434 (m), 1384 (s), 1210 (m), 1054 (m), 807 (m); H
NMR (300 MHz, CDCl3) δ =15.0 (s, 1H), 8.51 (d, 1H, 3J = 2.4 Hz),
7.50 (d, 1H, 3J = 2.4 Hz), 7.24 (m, 2H), 6.79 (dd, 1H, 3J = 5.2 Hz, 4J =
3.4 Hz), 3.22 (s, 12H), 2.34 (s, 3H); 13C NMR (CDCl3, 75 MHz) δ =
169.3, 163.1, 159.9, 144.9, 132.1, 127.8, 126.9, 124.5, 123.4, 121.8,
117.6, 36.5, 16.1; EI-MS, m/z (%) 356.1 (100). Anal. Calcd for
C18H21N5OS: C, 60.82; H, 5.95; N, 19.70. Found: C, 60.66; H, 5.77;
N, 19.52.
Compound 13. Prepared according to general procedure 6:
compound 7 (60.0 mg, 0.150 mmol), p-(dibutylamino)-
phenylacetylene (41.4 mg, 0.180 mmol, 1.2 equiv) in a mixture of
benzene/triethylamine (5 mL/1 mL). Column chromatography on
silica gel eluting with petroleum ether/CH2Cl2 7:3 to 3:7 as eluant to
give compound 13 as a greenish amorphous powder (78.4 mg, 40%):
IR (ATR) ν in cm−1 2955 (m), 2923 (m), 2854 (m), 1736 (w), 1610
Compound 9. Prepared according to general procedure 4:
compound 7 (100.0 mg, 0.250 mmol), 4,4′,5,5′-tetramethyl-1,3,2-
dioxaboronic ester of 3,4-ethylenedioxythiophene (0.376 mmol, 100.7
mg, 1.5 equiv), and aqueous K2CO3 (69.2 mg, 0.500 mmol, 2 equiv) in
toluene (10 mL). Column chromatography on silica gel eluting with
petroleum ether/CH2Cl2 4:6 to CH2Cl2 as eluant to give compound 9
as a yellow powder (28.1 mg, 27%): mp 227−229 °C; IR (ATR) ν in
cm−1 3097 (w), 3058 (w), 2923 (m), 2857 (w), 1613 (m), 1564 (s),
1
(m), 1562 (s), 1509 (s), 1466 (w), 1435 (m), 1398 (s), 810 (s); H
NMR (200 MHz, CDCl3) δ = 8.39 (d, 1H, 3J = 2.4 Hz), 7.38 (d, 1H,
3J = 2.4 Hz), 6.96 (AB sys, 4H, JAB = 5.6 Hz, υoδ = 157.8 Hz), 3.30−
3.12 (m, 4H), 3.16 (s, 12H), 2.28 (s, 3H), 1.56 (m, 4H), 1.39−1.31
1
1511 (s), 1433 (m), 1393 (s), 1054 (m), 807 (m); H NMR (200
MHz, CDCl3) δ = 8.57 (d, 1H, 3J = 1.4 Hz), 7.64 (d, 1H, 3J = 1.4 Hz),
6.22 (s, 1H), 4.30 (m, 2H), 4.25 (m, 2H), 3.24 (s, 12H), 2.36 (s, 3H);
13C NMR (CDCl3, 50 MHz) δ = 162.6, 159.1, 142.4, 137.3, 132.9,
127.3, 125.0, 123.9, 117.9, 117.5, 96.4, 64.9, 64.7, 36.8, 16.6; EI-MS,
m/z (%) 413.1 (100). Anal. Calcd for C20H23N5O3S: C, 58.09; H,
5.61; N, 16.94. Found: C, 57.74; H, 5.47; N, 16.79.
3
(m, 4H), 0.95 (t, 6H, J = 4.8 Hz); 13C NMR (CDCl3, 75 MHz) δ =
169.8, 163.9, 160.7, 148.3, 136.9, 132.9, 130.2, 127.1, 118.2, 113.6,
111.7, 109.5, 88.6, 87.6, 51.1, 36.7, 36.5, 29.8, 20.7, 16.1, 14.2; EI-MS,
m/z (%) 500.2 (100). Anal. Calcd for C30H40N6O: C, 71.97; H, 8.05;
N, 16.79. Found: C, 72.35; H, 8.41; N, 16.94.
Compound 14. A Schlenk tube was charged with a solution of 4,4-
difluoro-1,3,5,7,8-pentamethyl-2-iodo-4-bora-3a,4a-diaza-s-indacene
(190.0 mg, 0.490 mmol), trimethylsilylacetylene (50.6 mg, 0.515
mmol, 1.05 equiv) in a mixture of benzene/diisopropylamine (10 mL/
2 mL). The solution was degassed with argon for 30 min, then
[Pd(PPh2)2Cl2] (5 mol %, 18.1 mg) and CuI (6 mol %, 5.9 mg) were
added. The mixture was stirred at rt for one night (monitored by
TLC). Compound 7 (195.4, 0.490 mmol), DBU (895.6 mg, 5.88
mmol, 12 equiv), and 40 mol % of H2O were then added, and the
solution was stirred for an additional 3 days. The solution was then
extracted with CH2Cl2, washed with water, dried over MgSO4, and
evaporated under vacuum. The residue was purified by column
chromatography on silica gel eluting with petroleum ether/CH2Cl2 8:2
to 0:10 as eluant to give compound 14 as a purple powder (181.1 mg,
66%): mp dec >270 °C; IR (ATR) ν in cm−1 2923 (w), 2866 (w),
1556 (s), 1510 (s), 1467 (m), 1395 (s), 1199 (s), 1063 (s), 980 (s);
Compound 10. Prepared according to general procedure 4:
compound 7 (50.0 mg, 0.125 mmol), 5′-hexyl-2,2′-bithiophene-5-
boronic acid pinacol ester (0.250 mmol, 94.3 mg, 2 equiv), and
aqueous K2CO3 (86.5 mg, 0.626 mmol, 5 equiv) in toluene (10 mL).
Column chromatography on silica gel eluting with petroleum ether/
CH2Cl2 8:2 to 5:5 as eluant to give compound 10 as a yellow
amorphous powder (26.6 mg, 41%): IR (ATR) ν in cm−1 2923 (m),
2855 (w), 1611 (m), 1562 (s), 1508 (s), 1434 (m), 1394 (s), 1383 (s),
1209 (m), 1053 (m), 790 (s); 1H NMR (200 MHz, CDCl3) δ = 8.45
3
3
3
(d, 1H, J = 2.2 Hz), 7.47 (d, 1H, J = 2.2 Hz), 7.13 (d, 1H, J = 3.9
Hz), 7.02 (d, 1H, 3J = 3.6 Hz), 6.97 (d, 1H, 3J = 3.6 Hz), 6.66 (d, 1H,
3
3J = 3.9 Hz), 3.23 (s, 12H), 2.77 (t, 2H, J = 7.4 Hz), 2.33 (s, 3H),
3
1.65 (m, 2H), 1.28 (m, 6H), 0.87 (t, 3H, J = 6.6 Hz); 13C NMR
(CDCl3, 50 MHz) δ = 170.0, 163.9, 160.7, 145.7, 143.5, 136.1, 135.4,
131.5, 127.4, 126.5, 125.2, 124.3, 124.2, 123.3, 122.6, 118.3, 36.7, 36.5,
32.1, 32.0, 30.6, 29.2, 23.0, 16.3, 14.3; EI-MS, m/z (%) 521.1 (100).
Anal. Calcd for C28H35N5OS2: C, 64.46; H, 6.76; N, 13.42. Found: C,
64.22; H, 6.44; N, 13.18.
3
1H NMR (200 MHz, CDCl3) δ = 14.8 (s, 1H), 8.40 (d, 1H, J = 2.0
3
Hz), 7.40 (d, 1H, J = 2.0 Hz), 6.09 (s, 1H), 3.22 (s, 12 H), 2.67 (s,
3H), 2.62 (s, 3H), 2.56 (s, 3H), 2.54 (s, 3H), 2.43 (s, 3H), 2.29 (s,
3H); 13C NMR (CDCl3, 75 MHz) δ = 169.4, 163.5, 155.3, 155.1,
142.1, 141.6, 104.4, 136.8, 133.5, 133.2, 130.2, 126.8, 126.7, 124.8,
121.9, 117.8, 112.7, 96.4, 79.5, 36.5, 36.3, 17.5, 16.7, 16.0, 15.9, 15.3,
14.6; EI-MS, m/z (%) 557.2 (100). Anal. Calcd for C30H34BF2N7O: C,
64.64; H, 6.15; N, 17.59. Found: C, 64.52; H, 5.82; N, 17.38.
Compound 11. A Schlenk flask was charged with compound 7
(50.0 mg, 0.125 mmol), styrene (0.250 mmol, 0.029 mL, 2 equiv), and
K2CO3 (26.0 mg, 0.188 mmol, 1.5 equiv) in a mixture of benzene (2
mL) and DMF (6 mL). The solution was degassed with argon for 30
min, then [Pd(PPh3)2Cl2] (10 + 10 mol %) was added. The mixture
was stirred at 80 °C for 11 h (monitored by TLC). The solution was
extracted with CH2Cl2, washed with water, dried over MgSO4, and
evaporated under vacuum. The residue was purified by column
chromatography on silica gel eluting with petroleum ether/CH2Cl2 8:2
to 6:4 as eluant to give compound 11 as a white powder (13.0 mg,
28%): mp 180−182 °C; IR (ATR) ν in cm−1 3097 (w), 3058 (w),
2922 (m), 2850 (w), 1611 (m), 1563 (s), 1557 (s), 1509 (s), 1434
Compound 15. Prepared according to general procedure 5:
compound 7 (50.0 mg, 0.125 mmol), 1-ethynylpyrene (31.2 mg, 0.138
mmol, 1.1 equiv) in a mixture of benzene/triethylamine (5 mL/1 mL).
The solution was degassed with argon for 30 min, then [Pd(PPh3)4]
(10 mol %, 15.0 mg) and CuI (12 mol %, 3.0 mg) were added.
Column chromatography on silica gel eluting with petroleum ether/
CH2Cl2 7:3 to 5:5 as eluant to give an orange powder (79.0 mg, 41%):
mp dec >250 °C; IR (ATR) ν in cm−1 2920 (w), 1610 (m), 1569 (m),
1
(m), 1384 (s), 1210 (m), 1056 (m), 810 (s); H NMR (300 MHz,
3
3
(CD3)2CO) δ = 8.43 (d, 1H, J = 2.2 Hz), 7.61 (d, 1H, J = 2.2 Hz),
1
3
3
3
1513 (s), 1389 (s), 845 (s); H NMR (200 MHz, CDCl3) δ = 14.85
7.57 (d, 2H, J = 7.8 Hz), 7.35 (t, 2H, J = 7.7 Hz), 7.22 (t, 1H, J =
7.9 Hz), 7.22 (d, 1H, 3J = 16.0 Hz), 7.1 (d, 1H, 3J = 16.0 Hz), 3.24 (s,
12H), 2.27 (s, 3H); 13C NMR (CDCl3, 75 MHz) δ = 160.2, 138.1,
132.1, 131.7, 131.6, 129.1, 129.0, 128.8, 128.7, 128.5, 128.2, 127.1,
126.3, 126.0, 125.8, 36.6, 16.4; EI-MS, m/z (%) 375.2 (100). Anal.
Calcd for C22H25N5O: C, 70.38; H, 6.71; N, 18.65. Found: C, 70.11;
H, 6.54; N, 18.47.
(s, 1H), 8.70 (d, 1H, 3J = 9.3 Hz), 8.59 (d, 1H, 3J = 2.2 Hz), 8.26−8.00
(m, 8H), 7.61 (d, 1H, 3J = 2.2 Hz), 3.25−3.19 (m, 12H), 2.33 (s, 3H);
13C NMR (CD2Cl2, 75 MHz) δ = 168.8, 162.9, 160.7, 136.3, 131.1,
130.9, 130.7, 130.4, 130.0, 128.9, 127.7, 127.6, 127.4 126.8, 126.5,
125.8, 125.2, 125.0, 124.1, 123.8, 118.1, 117.5, 111.8, 95.6, 85.7, 35.9,
35.6, 15.3; EI-MS, m/z (%) 497.2 (100). Anal. Calcd for C32H27N5O:
C, 77.24; H, 5.47; N, 14.07. Found: C, 77.04; H, 5.25; N, 13.69.
Compound 16. Prepared according to general procedure 5:
compound 7 (50.0 mg, 0.125 mmol), 1-ethynylperylene (36.3 mg,
Compound 12. Prepared according to general procedure 5:
compound 7 (50.0 mg, 0.125 mmol), 4-ethynyltoluene (17.5 mg,
0.150 mmol, 2 equiv) in a mixture of benzene/triethylamine (5 mL/1
K
dx.doi.org/10.1021/jo301059u | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Featured Article
0.131 mmol, 1.05 equiv) in a mixture of benzene/triethylamine (5
mL/1 mL), [Pd(PPh3)4] (10 mol %, 14.5 mg), and CuI (12 mol %,
3.0 mg) were added. Column chromatography on silica gel eluting
with petroleum ether/CH2Cl2 9:1 to 4:6 as eluant to give compound
16 as an orange powder (32.6 mg, 48%): mp dec >270 °C; IR (ATR)
ν in cm−1 2922 (w), 1611 (m), 1574 (s), 1507 (s), 1403 (s), 1391 (s),
1382 (s), 809 (s), 761 (s); 1H NMR (200 MHz, CDCl3) δ = 14.91 (s,
1H), 8.53 (d, 1H J = 2.0 Hz), 8.35 (d, 1H, J = 8.2 Hz), 8.27−8.14
(m, 4H), 7.78−7.26 (m, 7H), 3.26−3.22 (m, 12H), 2.33 (s, 3H); due
to the low solubility of the compound, the carbon NMR spectra have
not been determined; EI-MS, m/z (%) 547.2 (100). Anal. Calcd for
C36H29N5O: C, 78.95; H, 5.34; N, 12.79. Found: C, 78.61; H, 5.12; N,
12.43.
mg, 50%): mp dec >270 °C; IR (ATR) ν in cm−1 2923 (w), 2867 (w),
1556 (s), 1511 (s), 1479 (m), 1446 (w), 1398 (s), 1195 (s), 1057 (s),
979 (s); 1H NMR (200 MHz, CDCl3) δ = 14.72 (s, 1H), 8.17 (d, 1H,
3
3J = 1.9 Hz), 7.40 (d, 1H, J = 1.9 Hz), 6.09 (s, 1H), 3.23 (s, 12H),
2.71 (s, 3H), 2.63 (s, 3H), 2.61 (s, 3H), 2.54 (s, 3H), 2.44 (s, 3H),
2.33 (s, 3H); 13C NMR (CDCl3, 75 MHz) δ = 168.9, 165.7, 155.4,
152.2, 151.6, 151.1, 142.6, 137.0, 140.0, 133.0, 131.9, 130.6, 128.9,
129.4, 126.3, 122.8, 122.1, 105.3, 35.8, 21.05, 17.3, 17.0, 15.4, 14.3,
13.5; TOF HR-MS EI, exact mass 557.2880, calcd 557.2886 for
C30H34BF2N7O.
3
3
ASSOCIATED CONTENT
* Supporting Information
■
S
Compound 17. Prepared according general procedure 3:
compound 6 (600.0 mg, 2.19 mmol), ICl (534.6 mg, 3.29 mmol),
MeOH (50 mL), and DMF (50 mL). The crude product was
recrystallized from EtOH/nonane to give compound 17 as a pale
yellow powder (871.4 mg, 99%): mp 211−213 °C; IR (ATR) ν in
cm−1 2916 (w), 2863 (w), 1600 (m), 1567 (s), 1511 (s), 1450 (m),
1391 (s), 1361 (m), 804 (s), 698 (s); 1H NMR (200 MHz, CDCl3) δ
X-ray crystal structure determination parameters for 8, 13, and
18, as well as proton and carbon NMR traces for all
compounds. Absorption, emission, and excitation spectra for
each compound are also provided. This material is available free
of charge via the Internet at http://pubs.acs.org.
1
3
3
= 15.14 (s, 1H), 8.15 (d, H, J = 2.0 Hz), 7.67 (d, 1H, J = 2.0 Hz),
3.20 (s, 12H), 2.29 (s, 3H); 13C NMR (CDCl3, 50 MHz) δ = 168.9,
163.4, 158.5, 143.1, 129.6, 129.2, 118.3, 85.7, 36.6, 36.3, 20.2; EI-MS,
m/z (%) 400.0 (100). Anal. Calcd for C14H18IN5O: C, 42.12; H, 4.54;
N, 17.54. Found: C, 41.94; H, 4.28; N, 17.27.
AUTHOR INFORMATION
Corresponding Author
*E-mail: ziessel@unistra.fr.
■
Compound 18. Prepared according to general procedure 4:
compound 17 (50.0 mg, 0.125 mmol), 2-thienylboronic acid (0.500
mmol, 64.2 mg, 4 equiv), and aqueous K2CO3 (86.5 mg, 0.626 mmol,
5 equiv) in toluene (10 mL). Column chromatography on silica gel
eluting with petroleum ether/CH2Cl2 4:6 to 2:8 as eluant to give
compound 18 as a yellow powder (21.0 mg, 47%): mp 227−228 °C;
IR (ATR) ν in cm−1 3097 (w), 3058 (w), 2923 (m), 2857 (w), 1611
(m), 1566 (s), 1506 (s), 1454 (w), 1434 (w), 1401 (s), 1383 (s), 1371
(s), 807 (s), 708 (s); 1H NMR (200 MHz, CDCl3) δ = 14.98 (s, 1H),
8.16 (d, 1H, 3J = 2.4 Hz), 7.62 (dd, 1H, 3J = 4.1 Hz, 4J = 1.3 Hz), 7.55
(d, 1H, 3J = 2.4 Hz), 7.31 (dd, 1H, 3J = 5.3 Hz, 4J = 1.3 Hz), 7.13−7.08
(m, 1H), 3.21 (s, 12H), 2.37 (s, 3H); 13C NMR (CDCl3, 50 MHz) δ =
169.8, 163.4, 156.6, 140.0, 132.9, 128.5, 126.9, 125.3, 124.7, 122.6,
118.6, 36.5, 36.4, 20.8; EI-MS, m/z (%) 356.1 (100). Anal. Calcd for
C18H21N5OS: C, 60.82; H, 5.95; N, 19.70. Found: C, 60.72; H, 5.62;
N, 19.42.
ACKNOWLEDGMENTS
■
We thank the Centre National de la Recherche Scientifique
(CNRS) and ANR Programme Blanc 2009, ANR-09-Blan-
0081-01, for financial support of this work, and Professor Jack
Harrowfield (ISIS in Strasbourg) for a critical reading of this
manuscript prior to publication. The ANR is acknowledged for
a PhD grant to S.R.
REFERENCES
■
(1) Sauer, M.; Hofkens, J.; Enderlein, J. Handbook of Fluorescence
Spectroscopy and Imaging: From Ensemble to Single Molecules; Wiley-
VCH: Weinheim, Germany, 2010.
(2) Sabnis, R. W. Handbook of Biological Dyes and Stains. Synthesis and
Industrial Applications; Wiley & Sons: Hoboken, NJ, 2010.
(3) Levenson, R. M.; Mansfield, J. R. Cytometry 2006, 69, 748−758.
Compound 19. Prepared according to general procedure 4:
compound 17 (100.0 mg, 0.250 mmol), 4,4′,5,5′-tetramethyl-1,3,2-
dioxaboronic ester of 3,4-ethylendioxythiophene (0.376 mmol, 100.7
mg, 1.5 equiv), and aqueous K2CO3 (69.2 mg, 0.500 mmol, 2 equiv) in
toluene (8 mL). Column chromatography on silica gel eluting with
petroleum ether/CH2Cl2 5:5 to CH2Cl2 as eluant to give compound
19 as a yellow powder (26.9 mg, 27%): mp 237−239 °C; IR (ATR) ν
in cm−1 2923 (m), 2866 (w), 1611 (m), 1566 (s), 1510 (s), 1435 (m),
1403 (s); 1H NMR (200 MHz, CDCl3) δ = 14.90 (s 1H), 8.12 (d, 1H,
̀
(4) Geissler, D.; Charbonniere, L. J.; Ziessel, R. F.; Butlin, N. G.;
Lohmannsroben, H.-G.; Hildebrandt, N. Angew. Chem., Int. Ed. 2010,
̈
̈
49, 1396−1401.
(5) (a) Lakowicz, J. R. Principles of Fluorescence Spectroscopy, 3rd ed.;
Springer: New York, 2006. (b) Wang, L.; Tan, W. Nano Lett. 2006, 6,
84−88.
(6) (a) Ziessel, R.; Harriman, A. Chem. Commun. 2011, 47, 611−631.
(b) Boens, N.; Leen, V.; Dehaen, W. Chem. Soc. Rev. 2012, 41, 1130−
1172.
3
3J = 2.2 Hz), 7.76 (d, 1H, J = 2.2 Hz), 6.38 (s, 1H), 4.31−4.23 (m,
4H), 3.29 (s, 12H), 2.36 (s, 3H); 13C NMR (CDCl3, 75 MHz) δ =
169.9, 163.5, 156.8, 141.2, 138.2, 134.1, 128.1, 126.7, 120.8, 118.1,
113.6, 99.0, 64.8, 64.5, 36.3, 20.9; EI-MS, m/z (%) 413.1 (100). Anal.
Calcd for C20H23N5O3S: C, 58.09; H, 5.61; N, 16.94. Found: C, 57.89;
H, 5.32; N, 16.64.
(7) (a) Harriman, A.; Mallon, L.; Ziessel, R. Chem.Eur. J. 2008, 14,
11461−11473. (b) Harriman, A.; Mallon, L. J.; Goeb, S.; Ulrich, G.;
Ziessel, R . Chem.Eur. J. 2009, 15, 4553−4564.
(8) Harriman, A.; Izzet, G.; Ziessel, R. J. Am. Chem. Soc. 2006, 128,
10868−10875.
(9) Wan, C.-W.; Burghart, A.; Chen, J.; Bergstrom, F.; Johansson, L.
B.-Å.; Wolford, M. F.; Kim, T. G.; Topp, M. R.; Hochstrasser, R. M.;
̈
Compound 20. A Schlenk tube was charged with a solution of 4,4-
difluoro-1,3,5,7,8-pentamethyl-2-iodo-4-bora-3a,4a-diaza-s-indacene
(100.0 mg, 0.258 mmol), trimethylsilylacetylene (26.6 mg, 0.271
mmol, 1.05 equiv) in a mixture of benzene/diisopropylamine (10 mL/
2 mL). The solution was degassed with argon for 30 min, then
[Pd(PPh3)2Cl2] (10 mol %, 18.0 mg) and CuI (12 mol %, 5.9 mg)
were added. The mixture was stirred at rt for one night (monitored by
TLC). Compound 17 (103.0, 0.258 mmol), DBU (470.8 mg, 3.09
mmol, 12 equiv), and 40 mol % of H2O were then added and the
solution was stirred for an additional 10 days. The solution was then
extracted with CH2Cl2, washed with water, dried over MgSO4, and
evaporated under vacuum. The residue was purified by column
chromatography on silica gel eluting with petroleum ether/CH2Cl2 9:1
to CH2Cl2 as eluant to give compound 20 as a purple powder (72.1
́
Burgess, K. Chem.Eur. J. 2003, 9, 4430−4441.
(10) Weller, A. Z. Elektrochem. 1956, 60, 1144−1147.
(11) (a) Goodman, J.; Brus, L. E. J. Am. Chem. Soc. 1978, 100, 7472.
(b) Nagaoka, S.; Hirota, N.; Sumitani, M.; Yoshihara, K. J. Am. Chem.
Soc. 1983, 105, 4220−4226 and references cited therein..
(12) (a) Beckett, A.; Porter, G. Trans. Faraday Soc. 1963, 59, 2051−
2057. (b) Gupta, A.; Yavrouian, A.; DiStefano, S.; Merritt, C. D.; Scott,
G . W. Macromolecules 1980, 13, 821−825. (c) Richard, H.; Leduc, M;
Lagrange, A. PCT/FR97/01995 WO 98/25922.
(13) Werner, T. J. Phys. Chem. 1979, 83, 320−326.
(14) Woolfe, G. J.; Melzig, M.; Schneider, S.; Dorr, F. Chem. Phys.
1983, 77, 213−221.
̈
L
dx.doi.org/10.1021/jo301059u | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Featured Article
(15) Barbara, P. F.; Brus, L. E.; Rentzepis, P. M. J. Am. Chem. Soc.
1980, 102, 5631−5635.
(43) Rondeau-Gagne,
́
S.; Curutchet, C.; Grenier, F.; Scholes, G. D.;
Morin, J. F. Tetrahedron 2010, 66, 4230−4242.
(44) Note in some cases the hydrogen-bonded phenolic proton is not
observed.
(16) (a) Rossetti, R.; Raybord, R.; Haddon, R. C.; Brus, L. E. J. Am.
Chem. Soc. 1980, 102, 6913−6916. (b) Rossetti, R.; Raybord, R.;
Haddon, R. C.; Brus, L. E. J. Am. Chem. Soc. 1981, 103, 4303−4309.
(17) (a) Shizuka, H.; Machii, M.; Higaki, Y.; Tanaka, M.; Tanaka, I. J.
Phys. Chem. 1985, 89, 320−325. (b) Keck, J.; Roessler, M.; Schroeder,
́
C.; Stueber, G. J.; Waiblinger, F.; Stein, M.; LeGourrierec, D.; Kramer,
H. E. A.; Hoier, H.; Henkel, S.; Fischer, P.; Port, H.; Hirsch, T.; Rytz,
G.; Hayoz, P. J. Phys. Chem. B 1998, 102, 6975−6979.
(18) The literature on 2,4,6-trifunctionalized 1,3,5-triazine is too
large to be extensively cited; consequently, we have restricted our
overview on 2-phenyl functionalized-1,3,5-triazine. See for instance:
(a) Mur, V. I. Russ. Chem. Rev. 1964, 33, 92−103 and references cited
therein. (b) Giacomelli, G.; Porcheddu, A.; De Luca, L. Curr. Org.
Chem. 2004, 8, 1497−1519.
(19) Blotny, G. Tetrahedron 2006, 62, 9507−9522.
(20) Szatyłowicz, H. J. Phys. Org. Chem. 2008, 21, 897−914.
(21) Lee, J. W.; Ha, H.-H.; Vendrell, M.; Bork, J. T.; Chang, Y.-T.
Aust. J. Chem. 2011, 64, 540−544 and references cited therein..
(22) Islam, M.; Mondal, P.; Roy, A. S.; Tuhina, K. Transition Met.
Chem. 2010, 35, 491−499.
(23) Bonardi, L.; Ulrich, G.; Ziessel, R. Org. Lett. 2008, 10, 2183−
2186.
(24) Mio, M. J.; Kopel, L. C.; Braun, J. B.; Gadzikwa, T. L.; Hull, K.
L.; Brisbois, R. G.; Markworth, C. J.; Grieco, P. A. Org. Lett. 2002, 4,
3199−3202.
(25) Shizuka, H.; Matsui, K.; Okamura, T.; Tanaka, I. J. Phys. Chem.
1975, 79, 2731−2734.
(26) (a) Shizuka, H.; Matsui, K.; Hirata, Y.; Tanaka, I. J. Phys. Chem.
1976, 80, 2070−2072. (b) Shizuka, H.; Matsui, K.; Hirata, Y.; Tanaka,
I. J. Phys. Chem. 1977, 81, 2243−2246.
(27) Olmsted, J., III. J. Phys. Chem. 1979, 83, 2581−2584.
(28) (a) Ziessel, R.; Ulrich, G.; Harriman, A. New J. Chem. 2007, 31,
496−501. (b) Ziessel, R. CR Acad. Sci. Chim. 2007, 10, 622−629.
(c) Loudet, A.; Burgess, K. Chem. Rev. 2007, 107, 4891−4932.
(d) Ulrich, G.; Ziessel, R.; Harriman, A. Angew. Chem., Int. Ed. 2008,
47, 1184−1201.
(29) (a) Thoresen, L. H.; Kim, H.; Welch, M. B.; Burghart, A.;
Burgess, K. Synlett 1998, 1276−1278. (b) Chen, T.; Boyer, J. H.;
Trudell, M. L. Heteroat. Chem. 1997, 8, 31−39. (c) Sathyamoorthi, G.;
Wolford, L. T.; Haag, A. M.; Boyer, J. H. Heteroat. Chem. 1994, 5,
245−000. (d) Burghart, A.; Kim, H.; Wech, M. B.; Thorensen, L. H.;
Reibenspies, J.; Burgess, K. J. Org. Chem. 1999, 64, 7813−7819.
(30) Ulrich, G.; Nastasi, F.; Retailleau, P.; Puntoriero, F.; Ziessel, R.;
Campagna, S. Chem.Eur. J. 2008, 14, 4381−4392.
(31) Devadoss, C.; Bharathi, P.; Moore, J. S. J. Am. Chem. Soc. 1996,
118, 9635−9644.
(32) Coulson, D. R. Inorg. Synth. 1972, 13, 121−124.
(33) Dangles, O.; Guibe, F.; Balavoine, G. J. Org. Chem. 1987, 52,
4984−4993.
(34) Inouye, M.; Hyodo, Y.; Nakazumi, H. J. Org. Chem. 1999, 64,
2704−2710.
(35) Hissler, M.; Harriman, A.; Khatyr, A.; Ziessel, R. Chem.Eur. J.
1999, 5, 3366−3381.
(36) Molin, D. M.; Gasparini, G.; Scrimin, P.; Rastrelli, F.; Prins, L. J.
Chem. Commun. 2011, 47, 12476−12478.
(37) Sorgel, S.; Tokunaga, N.; Sasaki, K.; Okamoto, K.; Hayashi, T.
̈
Org. Lett. 2008, 10, 589−592.
(38) Collis, G. E.; Burrell, A. K.; Scott, S. M.; Officer, D. L. J. Org.
Chem. 2003, 68, 8974−8983.
(39) Zhu, W.; Ma, D. Org. Lett. 2006, 8, 261−263.
(40) Bolognesi, A.; DiGianvincenzo, P.; Giovanella, U.; Mendichi, R;
Schieroni, A. G. Eur. Polym. J. 2008, 44, 793−800.
(41) Shah, M.; Thangaraj, K.; Soong, M.-L.; Wolford, L. T.; Boyer, J.
H.; Politzer, I. R.; Pavlopoulos, T. G. Heteroat. Chem. 1990, 1, 389.
(42) Bonardi, L.; Ulrich, G.; Ziessel, R. Org. Lett. 2008, 10, 2183−
2186.
M
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