Synthesis, photophysical, and two-photon absorption properties of elongated phosphane oxide and sulfide derivatives

Article abstract of DOI:10.1002/asia.201000681

A series of rod-shaped and related three-branched push-pull derivatives containing phosphane oxide or phosphane sulfide (PO or PS)a-as an electron-withdrawing group conjugated to electron-donating groups, such as amino or ether groups, with a conjugated rod consisting of arylene-vinylene or arylene-ethynylene building blocksa-were prepared. These compounds were efficiently synthesized by a Grignard reaction followed by Sonogashira coupling. Their photophysical properties including absorption, emission, time-resolved fluorescence, and two-photon absorption (TPA) were investigated with special attention to structure-property relationships. These fluorophores show high fluorescence quantum yields and solvent-dependent experiments reveal that efficient intramolecular charge transfer occurs upon excitation, thereby leading to highly polar excited states, the polarity of which can be significantly enhanced by playing on the end groups and conjugated linker. Rod-shaped and related three-branched systems show similar fluorescence properties in agreement with excitation localization on one of the push-pull branches. By using stronger electron donors or replacing the arylene-ethynylene linkers with an arylene-vinylene one induces significant redshifts of both the low-energy one-photon absorption and TPA bands. Interestingly, a major enhancement in TPA responses is observed, whereas OPA intensities are only weakly affected. Similarly, phosphane oxide derivatives show similar OPA responses than the corresponding sulfides but their TPA responses are significantly larger. Finally, the electronic coupling between dipolar branches promoted by common PO or PS acceptor moieties induces either slight enhancement of the TPA responses or broadening of the TPA band in the near infrared (NIR) region. Such behavior markedly contrasts with triphenylamine-core-mediated coupling, which gives evidence for the different types of interactions between branches.

Full text of DOI:10.1002/asia.201000681

FULL PAPERS
DOI: 10.1002/asia.201000681
Synthesis, Photophysical, and Two-Photon Absorption Properties of
Elongated Phosphane Oxide and Sulfide Derivatives
Valꢀrie Alain-Rizzo,[a] Delphine Drouin-Kucma,[b] Cꢀdric Rouxel,[b] Issa Samb,[c]
Jꢀrꢀmy Bell,[a] Patrick Y. Toullec,[c] Vꢀronique Michelet,*[c] Isabelle Leray,*[a] and
Mireille Blanchard-Desce*[b]
Abstract: A series of rod-shaped and
related three-branched push–pull deriv-
atives containing phosphane oxide or
phosphane sulfide (PO or PS)—as an
electron-withdrawing group conjugated
to electron-donating groups, such as
amino or ether groups, with a conjugat-
ed rod consisting of arylene–vinylene
experiments reveal that efficient intra-
molecular charge transfer occurs upon
excitation, thereby leading to highly
polar excited states, the polarity of
which can be significantly enhanced by
playing on the end groups and conju-
gated linker. Rod-shaped and related
three-branched systems show similar
fluorescence properties in agreement
with excitation localization on one of
the push–pull branches. By using stron-
ger electron donors or replacing the ar-
ylene–ethynylene linkers with an ary-
lene–vinylene one induces significant
redshifts of both the low-energy one-
photon absorption and TPA bands. In-
terestingly, a major enhancement in
TPA responses is observed, whereas
OPA intensities are only weakly affect-
ed. Similarly, phosphane oxide deriva-
tives show similar OPA responses than
the corresponding sulfides but their
TPA responses are significantly larger.
Finally, the electronic coupling be-
tween dipolar branches promoted by
common PO or PS acceptor moieties
induces either slight enhancement of
the TPA responses or broadening of
the TPA band in the near infrared
(NIR) region. Such behavior markedly
contrasts with triphenylamine-core-
mediated coupling, which gives evi-
dence for the different types of interac-
tions between branches.
or
arylene–ethynylene
building
blocks—were prepared. These com-
pounds were efficiently synthesized by
a Grignard reaction followed by Sono-
gashira coupling. Their photophysical
properties including absorption, emis-
sion, time-resolved fluorescence, and
two-photon absorption (TPA) were in-
vestigated with special attention to
structure–property relationships. These
fluorophores show high fluorescence
quantum yields and solvent-dependent
Keywords: charge transfer · fluo-
rescence · phosphanes · solvato-
chromism · two-photon absorption
Introduction
for potential applications in biology[1] or for the environ-
ment with the development of sensors.[2] In the course of
our recent ongoing program toward novel fluorophores, we
have recently prepared and evaluated the photophysical
Over the past few years significant research has been direct-
ed toward the development of new fluorescent molecules
[c] Dr. I. Samb, Dr. P. Y. Toullec, Dr. V. Michelet
Ecole Nationale Supꢀrieure de Chimie de Paris
Chimie ParisTech, Laboratoire Charles Friedel
UMR CNRS 7223, 11 rue P. et M. Curie
75231 Paris Cedex 05 (France)
[a] Dr. V. Alain-Rizzo, J. Bell, Dr. I. Leray
PPSM, ENS de Cachan, CNRS (UMR 8531)
UniverSud Paris, 61 avenue du Prꢀsident Wilson
94230 Cachan (France)
Fax : (+33)147402454
E-mail: isabelle.leray@ppsm.ens-cachan.fr
Fax : (+33)144071062
E-mail: veronique-michelet@chimie-paristech.fr
[b] D. Drouin-Kucma, C. Rouxel, Dr. M. Blanchard-Desce
Universitꢀ de Rennes 1, CNRS
Chimie et Photonique Molꢀculaires (UMR6510)
Campus de Beaulieu Case 1003
35042, Rennes Cedex (France)
Fax : (+33)223236955
E-mail: mireille.blanchard-desce@univ-rennes1.fr
1080
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Chem. Asian J. 2011, 6, 1080 – 1091

properties of novel molecules 1–2, bearing a phosphane
oxide (PO) as an acceptor group and a methoxy or a dime-
thylamino group as the donor moiety.[3–7] These systems ex-
hibit high fluorescence quantum yields and the excitation in-
duces very efficient charge redistribution in the molecules,
typical of an intramolecular charge-transfer transition
(ICT). We also demonstrated that the electronic properties
of 1–2 are strongly affected by the nature of the donor, the
length, and the nature of the conjugated linker between the
core acceptor and the peripheral donors. The photophysical
properties of the star-shaped fluorophores (1a–b) and rod-
shaped (2a–b) fluorophores were found to be similar, which
indicated that emission originates from a single branch for
all star-shaped derivatives. These branched derivatives—in
which dipolar ICT branches are connected by a common ac-
ceptor core—are thus interesting model compounds for in-
vestigating the ability of the triphenylphosphane oxide
(TPPO) moiety to promote coupling between dipolar
branches, thereby leading to modification of (linear or non-
linear) absorption properties. Whereas the donating triphe-
nylamine moiety is known as an efficient electron-donating
coupling unit promoting coherent coupling between branch-
es (both in octupolar derivatives[8–11] and in branched deriva-
tives),[12] little is known about using TPPO as an electron-
withdrawing coupling unit possibly promoting excitonic cou-
pling.
The nature and strength of the electronic coupling pro-
moted by a (electron-donating or -withdrawing) coupling
unit can be evaluated by investigating the photophysical and
two-photon absorption (TPA) properties of derivatives built
from dipolar branches connected by such moieties. Such
methodology has already proven useful in the case of the
triphenylamine core unit, which was shown to be a potent
coupling unit[13,14] and 1,3,5-triphenylbenzene (shown to be a
Chem. Asian J. 2011, 6, 1080 – 1091
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V. Michelet, I. Leray, M. Blanchard-Desce et al.
FULL PAPERS
poor coupling unit).[14,15] Hence we have investigated the
TPA properties of the previously described compounds (1–
2) as well as of the newly synthesized derivatives 3–4 for
which the conjugated path has been modified by the re-
placement of one phenylene–ethynylene (PE) building
block with a phenylene–vinylene one (PV) to favor a red-
shift of both TPA and one-photon absorption (OPA) spectra
and enhance TPA responses.[15,16] Following this aim, we
have also been interested in investigating the behavior of
phosphane sulfide (PS) analogues (5a, 5b, 6a, and 6b), an-
ticipating that the triphenylphosphane sulfide (TPPS)
moiety would affect coupling and influence both fluores-
cence and TPA properties. Having no precedent and no
data for such derivatives, we wish therefore to describe
therein our study concerning the synthesis, photophysical,
and TPA properties of these new derivatives.
spectively (Scheme 1).[3] The introduction of one or three
phenyl-vinylene arms was envisaged through the iodostyr-
ene intermediates 10 and 11. They were easily prepared by
starting from 4-iodobenzaldehyde and the phosphonium salt
bearing either an O-octyl or N-(octyl)2 group.[17] The Wittig
reaction employed compounds 12 and 13, respectively
(using solid-liquid phase-transfer conditions);[18] this afford-
ed the desired iodostyrene derivatives 10 and 11 in 92%
and 75% isolated yield, respectively.[16,19] It should be noted
that the treatment of the crude reaction mixture with cata-
lytic iodine under natural light led to complete E stereo-
chemistry of the alkene function. The Sonogashira cross-
couplings[20] were then performed either on trialkyne 8 or on
monoalkyne 9. The star-shaped phosphane oxides 3a and 3b
were obtained in 85 and 88% yield, respectively. The mono-
substituted analogues 4a and 4b were isolated in good yield.
The syntheses of the phosphane sulfides 5–6 followed the
same strategy (Scheme 2). Starting from the same precursor
7, the phosphorylation using the Grignard derivative in the
presence of trichlorophosphane or chlorodiphenylphosphane
was this time followed by treatment with elemental sulfur
and the desilylation step under basic conditions afforded the
key intermediates 8’ and 9’ in 42 and 52% overall yield, re-
spectively (Scheme 2).[3]
Results and Discussion
The preparation of 1–2 was realized according to previous
methodologies.[3,5] The synthesis of 3–6 has been conducted
as described in Schemes 1 and 2. By starting from the com-
The Sonogashira cross-cou-
plings between the thiophos-
phano products 8’ (9’, respec-
tively) and the iodostyrene de-
rivatives 10 or 11 were per-
formed in the presence of palla-
dium catalyst (5 mol%) and
copper iodide (15 mol%) in tol-
uene at 608C; this led to the
desired phosphane sulfides 5a–
b (6a–b, respectively) in 71 and
63% (70 and 65%, respective-
ly) isolated yield.
Photophysical Properties
The absorption and emission
spectra of the newly synthe-
sized phosphane oxide com-
pounds are displayed in Figure-
s 1a and b. The absorption and
emission data of all compounds
(including phosphane sulfide
Scheme 1. Syntheses of phosphane oxides 3 and 4 and iodostyrene intermediates 10 and 11: a) 10 or 11, [PdCl2
ACHTUNGTRENNUNG(PPh3)2] (5 mol%), CuI (15 mol%), iPr2NH, toluene, 508C, 20 h; b) NaH, [18]crown-6, THF, 208C, then I2
(3mol%), CH2Cl2, RT, hn.
derivatives 5–6) together with
those previously reported for
the PO derivatives containing a
phenyl–ethynylene bridge are
mercially available 4-bromotrimethylsilyl phenylacetylene
(7), the phosphorylation by using the Grignard derivative in
the presence of trichlorophosphane or chlorodiphenylphos-
phane followed by the oxidation of the phosphorus atom
and the desilylation step under basic conditions afforded the
key intermediates 8 and 9 in 44 and 60% overall yield, re-
collected in Table 1. As previously observed for compounds
containing diphenylene–ethynylene bridges (PE2) as the
conjugated path between the donating peripheral groups
(compounds 1–2) and the TPPO moiety, the PO as well as
PS compounds containing phenylene–ethynylene phenyl-
ene–vinylene bridges (PE–PV; compounds 3–6) show an in-
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Chem. Asian J. 2011, 6, 1080 – 1091

Phosphane Oxide and Sulfide Derivatives
double bond (Table 1), in
agreement with increased elec-
tronic conjugation.
As reported earlier for quad-
ripolar fluorophores,[16] a 40%
decrease in the fluorescence
quantum yield is observed by
replacing the PE2 bridge with a
PE–PV bridge. This is most
probably related to the de-
creased rigidity of the conjugat-
ed path in the PE–PV bridge,
thereby leading to larger con-
formational flexibility favoring
nonradiative deactivation pro-
cesses. As expected, a marked
bathochromic shift of the ab-
sorption and emission spectra is
Scheme 2. Syntheses of phosphane sulfides 5 and 6: a) Mg/THF , 558C then PSCl3 or ClPPh2; b) S8/toluene,
958C; c) K2CO3, MeOH/CH2Cl2 (2:1), 8’ (42%, over 3 steps) and 9’ (52%, over 3 steps); d) 10 or 11, [PdCl2
ACHTUNGTRENNUNG(PPh3)2] (5 mol%), CuI (15 mol%), iPr2NH, toluene, 608C, 3 h.
Table 1. Photophysical properties of compounds 1–6 in chloroform.
abs
em
max
Compounds
lmax
10ꢀ4 emax
[mꢀ1 cmꢀ1
l
F[a]
Slope
[103 cmꢀ1
]
[b]
[nm]
G
]
[nm]
U
1a
2a
1b
2b
3a
4a
3b
4b
5a
6a
5b
6b
338
335
369
369
361
359
409
404
356
360
408
405
17.7
5.9
12.5
4.1
12.4
5.2
12.2
3.6
11.9
4.18
11.2
3.5
392
388
478
471
435
434
518
516
438
435
523
515
0.77
0.76
0.56
0.66
0.34
0.34
0.43
0.34
0.49
0.45
0.49
0.49
13.7
13.5
26.0
27.1
13.2
13.3
18.3
18.3
13.2
12.5
21.6
20.1
[a] Fluorescence quantum yield. [b] Slope value derived from the linear
variation of the Stokes shifts on the polarity–polarizability function of
the solvent (Lippert–Mataga correlation).
observed by increasing the electron-donating strength of the
peripheral groups (1b (2b–6b, respectively) versus 1a (2a–
6a, respectively)). This also leads to a slight decrease in the
fluorescence quantum yield in the case of compounds con-
taining the PE2 bridge, whereas no such effect is observed in
the case of compounds for which the PE2 bridge has been
replaced by the PE–PV bridge (3–4). The replacement of
the PO acceptor moiety by the PS core induces only a slight
hypochromic shift of the absorption and a slight bathochro-
mic shift of the emission band as well as a definite increase
in the fluorescence quantum yield (Table 1).
The effect of coupling several dipolar branches with a
common electron-withdrawing PO or PS moiety is already
noticeable on the absorption properties. Comparison of the
absorption properties of three-branched compound 3b and
its monomeric analogue 4b shows a redshift and an increase
in the maximum molar extinction coefficient per subchro-
mophore in the branched system (Table 1). A slight batho-
chromic and hyperchromic shift of the absorption band is
Figure 1. Normalized absorption of phosphane oxide derivatives 3 and 4
chloroform (top) and corrected normalized emission spectra of phos-
phane oxide derivatives 3 and 4 in chloroform (bottom).
tense band in the near UV/Vis blue region. A noticeable
bathochromic shift of both the absorption and the emission
spectra was observed by replacing the triple bond by a
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V. Michelet, I. Leray, M. Blanchard-Desce et al.
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also observed in the case of the branched compound 5b rel-
ative to its monomeric analogue 6b. In the case of the 3a/4a
pair, the effect is only a slight redshift for the three-
branched system as well as a broadening and consequent de-
crease in the maximum molar extinction coefficient per sub-
chromophore. In the case of the 5a/6a pair, a slight blueshift
and a definite broadening of the low-energy absorption
band (showing a clear shoulder at lower wavelengths) and
consequent decrease in maximum molar extinction coeffi-
cient per subchromophore (Table 1) is observed in the
three-branched system. The observed changes of absorption
properties when comparing three-branched derivatives with
their monomeric analogues demonstrate that interactions
take place between branches.
The emission bands of the three-branched phosphane
oxide and sulfide compounds are very similar to those of
their dipolar counterparts but are slightly redshifted as
shown in Figure 1b. From Table 1, we observe that the red-
shift depends on the nature of the end groups and connec-
tors. Larger redshifts are observed for more rigid connectors
(1a vs 2a and 1b vs 2b relative to 3a vs 4a and 3b vs 4b).
In addition, a stronger donor leads to more pronounced red-
shifts (in particular in the case of 1b and 5b). Such a red-
shift can be related to the proximity of dipolar branches in
relation with localization of emission (vide infra). Indeed
stronger electron donors lead to larger dipole moments and
thus generate larger dipole–dipole interactions between sub-
chromophores in three-branched systems.
Figure 2. Corrected normalized emission spectra of compounds 3b (top)
and 4b (bottom) in different solvents: a) Cyclohexane, b) dioxane,
c) CHCl3, d) CH2Cl2, e) EtOH, f) CH3CN, g) DMSO. DMSO=dimethyl
sulfoxide.
Nature of the Emitting Excited State
The solvatochromic behavior of PO and PS was investigated
to gain information about the nature of the excited state of
the star-shaped (i.e., three-branched) systems. In particular,
solvatochromic effects of the new fluorophores (3–4 and 5–
6) were studied and compared with the previously observed
PO derivatives data. As was reported earlier for derivatives
1–2,[5] increased polarity produces an important bathochro-
mic shift of the emission spectra but only a slight redshift of
the absorption spectra (Figure 2). This is a clear signature of
an intramolecular charge-transfer transition with a signifi-
cant increase in dipole moment in the excited state, thereby
leading to highly polar excited states.
Interestingly the solvatochromic behavior of the three-
branched derivative 3b is found to be similar to that of its
monomeric dipolar analogue 4b. Hence, the emissive excit-
ed state of the three-branched system is also strongly dipo-
lar. Such phenomenon is also observed for compounds 3a
and 4a (see Figure S2’ in the Supporting Information). Such
behavior is similar to that reported for three-branched octu-
polar systems built from a common triphenylamine donor
core[8–10] and points to excitation localization on one of the
branches of the branched derivatives occurring after excita-
tion, prior to emission. Further information on the polarity
of the excited state of the various phosphane oxide and sul-
fide derivatives can be gained by examination of the varia-
tion in the Stokes shifts function of polarity. This variation
can be fitted by using the well-known Lippert–Mataga equa-
tion[21] (Figure 3):
2
hca3
2
ð1Þ
vaꢀvb ¼
ðmeꢀmgÞ Df þ C
in which na and nf are the maximum absorption and fluores-
cence wavenumber, respectively, h is Planckꢂs constant, c is
the velocity of light, a is the radius of the cavity, me and mg
are the excited and ground-state dipole moments, and Df is
the orientation polarizability defined as:
eꢀ1
n2ꢀ1
ð2Þ
Df ¼
ꢀ
2e þ 1 2n2 þ 1
in which e is the static dielectric constant and n the optical
refractive index of the solvent.
As shown in Figure 3, in which the Stokes shift values in
various solvents are plotted against Df, for several PO deriv-
atives, a linear dependency is obtained, thus allowing the de-
termination of the slope values (Table 1). The slope values
are directly related to Dm/a3 thus giving information on the
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Phosphane Oxide and Sulfide Derivatives
slope values are found to be somewhat smaller when com-
paring related derivatives containing PE–PV bridges and a
PE2 conjugated path (1a–b vs 3a–b, 2a–b), thereby provid-
ing evidence that the triple bond leads to larger dipole mo-
ments in the excited state than for analogues with a double
bond. Such an effect is most probably related to the rigidity
of the linker as was observed earlier for one-dimensional
push–pull compounds containing different conjugated paths
and acceptor end groups (i.e., push–pull carotenoids and
polyenes).[22,23]
To further characterize the photophysical properties of
the synthesized compounds, time-resolved fluorescence
measurements were performed by using the single-photon-
counting method with picosecond laser excitation. The fluo-
rescence decays of phosphane oxide derivatives with PE–PV
linkers are displayed in Figure 4. The time constants ob-
tained by decay analysis for the phosphane oxide and sulfide
derivatives are gathered in Table 2.
For the compounds containing PE2 bridges (both mono-
and trisubstituted arms), satisfactory fits can be obtained by
considering a single exponential (c2R <1.25). For the com-
pounds containing
a PE–PV bridge, monoexponential
decays were obtained for the monosubstituted fluorescent
arm (compounds 4a and 4b). In contrast, satisfactory fits
are obtained only by considering two (phosphane sulfide de-
Figure 3. Lippert–Mataga correlations for phosphane oxide fluorophores
3a, 3b, 4a, and 4b (top) and phosphane sulfide fluorophores 5a, 5b, 6a,
and 6b (bottom).
polarity of the excited states of the different compounds.
The change in dipole moment values can then be derived if
accurate cavity size can be estimated for such compounds.
Alternatively, comparison of the slope values obtained for
chromophores of similar shape and size provides valuable
information on the polarity of the emitting excited states.
As clearly seen in Figure 3 and noted from Table 1, three-
branched phosphane oxides show similar solvatochromic
amplitude as their one-branch counterpart. This confirms
that emission originates from a dipolar branch (acting as a
subchromophore) due to excitation localization. We also ob-
serve from comparison of phosphane oxide and sulfide de-
rivatives that compounds bearing the stronger dialkylamino
donor (derivatives b) always show more pronounced solva-
tochromic behavior (i.e., larger slope values) than their ana-
logues bearing weaker electron-donating alkoxide end
groups (Figure 3a). Since the cavity sizes are the same be-
tween pairs of a and b derivatives; this provides evidence
that the dialkyamino compounds lead to more polar excited
states. Similarly, sulfide derivatives show larger slope values
than the corresponding oxide derivatives (Figure 3b), indi-
cative of more polar emitting excited states. In contrast, the
Figure 4. Fluorescence decays of the compounds 3a, 3b, 4a, and 4b in
chloroform.
Table 2. Fluorescence decay components ai and ti of compounds 1–6 in
chloroform.
Product
t1 [ns] (a1)
t2 [ns] (a2)
t3 [ns] (a3)
c2
R
1a
2a
1b
2b
3a
4a
3b
4b
5a
6a
5b
6b
0.74 (1)
0.78 (1)
1.52 (1)
1.52 (1)
0.70 (0.72)
0.65 (1)
1.28 (0.74)
1.24 (1)
0.72 (0.88)
0.69 (1)
1.36 (0.83)
1.24 (1)
1.05
1.02
1.07
0.12 (0.27)
0.18 (0.25)
0.09 (0.12)
0.22 (0.17)
2.17 (0.01)
4.01 (0.01)
1.10
1.03
1.11
1.33
1.09
1.07
1.14
1.07
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V. Michelet, I. Leray, M. Blanchard-Desce et al.
FULL PAPERS
rivatives) or three exponentials (phosphane oxide deriva-
tives) for the three-branched fluorescent compounds
(Figure 4). The main lifetime is similar to that of the related
rod-shaped derivatives, in agreement with localization of the
excitation on one of the subchromophoric branches. Addi-
tional lifetimes suggest that interactions occur in the excited
state of compounds 3a–b and 5a–b due to the conforma-
tionnal flexibility ((S)-cis to (S)-trans) they provide. Indeed
interactions between the excited subchromophoric branch
and other branches can lead to the formation of an “inter-
nal” excimer. Such phenomena have been reported earlier
in the case of multichromophoric derivatives for which
push–pull compounds are grafted in close proximity on a
common platform by a short flexible linker[24] and in the
case of bidentate PO derivatives.[7]
Two-Photon Properties
The TPA characteristics of compounds 1–6 were determined
in the 700–1000 nm spectral region by studying their two-
photon excited fluorescence, following the methodology de-
scribed by Webb and collaborators, and by using fs pulse ex-
citation and fluorescein as a reference compound. The TPA
data measured in chloroform are collected in Table 3. In all
cases we observe that the lowest energy band peaks at
about half the energy (i.e., twice the wavelength) of the
lowest energy one-photon absorption band, which indicates
that the lowest excited state is both one and two-photon al-
lowed.
Figure 5. TPA spectra of 4b/6b (top; & =4b, +=6b) and 3b/5b (bottom;
*
^
=3b, =5b) in chloroform.
whereas extinction coefficients are reduced by only 10 to
20% (Table 1).
Core Effect: TPPO Versus TTPS
End-Group Effect: Donor Strength
As clearly evidenced from Table 3 and illustrated in
Figure 5, the phosphane sulfides show much lower TPA re-
sponses than the corresponding phosphane oxides. The
slight redshift of the TPA peaks parallels the effect observed
for OPA peaks. However, the reduction in TPA cross-sec-
tions is much more pronounced than the hypochromic shift
of the OPA band. The TPA peak cross-sections in the NIR
region are typically reduced by a factor of three to four,
For all phosphane oxide and sulfide derivatives, increasing
the strength of electron-donating end groups results in a sig-
nificant bathochromic shift and pronounced enhancement of
the TPA band (Figure 6). Here again, the redshift of the
TPA band parallels the redshift of the OPA band. However,
whereas stronger electron-donating terminal groups gener-
ate a slight decrease in OPA, a major increase in the TPA
cross-sections in the NIR region is obtained, typically by a
factor of three to five for the
peak
TPA
cross-sections
Table 3. Two-photon absorption properties of compounds 1–6 in chloroform.
(Table 3).
[a]
max
TPA
Product
Neff
l
[nm]
s2max[b] [GM]
s2max/N[c] [GM]
s2max/MW [GMgꢀ1 mol]
s2max/Neff [GM]
1a
2a
1b
2b
3a
4a
3b
4b
5a
6a
5b
6b
38.2
23.7
38.2
23.7
38.2
23.7
38.2
23.7
38.2
23.7
38.2
23.7
<700
>135
>150
600
180
360
145
1300
650
120
85
>45
>50
200
180
120
145
420
650
40
>0.139
>0.295
0.595
0.435
0.284
0.238
0.811
0.903
0.093
0.136
0.259
0.231
>3.5
>6.3
15.7
7.6
9.4
6.1
34.1
27.5
3.1
3.6
11.0
7.2
Connector Effect: Phenylene–
Vinylene (PV) Versus
Phenylene–Ethynylene (PE)
Moieties
<700
760
760
750
750
820
820
740
750
820
830
Replacing
a phenylene–vinyl-
ene unit by a phenylene–ethy-
nylene unit in the conjugated
linker between the PO core and
the donating end groups also
induces a significant bathochro-
mic shift of the TPA spectra,
and leads to a major increase in
85
140
170
420
170
[a] Effective number of p electrons in the conjugated systems.[25] [b] TPA cross-section at maximum, 1 GM=
10ꢀ50 cm4 s.photonꢀ1. [c] Maximum TPA cross-section normalized with respect to the number of branches (N),
the number of p electrons (Neff), or the molecular weight (MW).
1086
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Chem. Asian J. 2011, 6, 1080 – 1091

Phosphane Oxide and Sulfide Derivatives
~
~
~
*
Figure 7. TPA spectra of 1a/3a (top; =1a, =3a) and 1b/3b (bottom;
Figure 6. TPA spectra of 1a/1b (top; =1a, =1b) and 3a/3b (bottom;
~
*
*
*
=3a, =3b) in chloroform.
=1b, =3b) in chloroform.
the TPA cross-sections in the NIR region (Figure 7). The
peak TPA cross-sections are enhanced by a factor of two to
three (the stronger enhancement being obtained for a stron-
ger terminal donor), whereas the maximum extinction coef-
ficients are found to decrease (the stronger donors also
giving rise to the larger effect). Hence, in that case, opposite
effects are obtained for OPA and TPA. Replacement of the
PE2 linker by the PE–PV linker is thus a successful strategy,
as was already observed in the case of symmetrical quadru-
polar derivatives.[16]
To further examine the effect of coupling between
branches on the TPA in phosphine oxide and sulfide deriva-
tives, we have compared the normalized TPA response by
using two different normalization procedures. The first one,
which is relevant for applications, such as optical limita-
tion,[10] is based on the molecular weight (MW). The different
s2max/MW values determined for the various derivatives are
gathered in Table 3. In the case of the PE2 derivatives, we
observe a major enhancement of the s2max/MW value for the
three-branched derivatives, whereas the PE–PV derivatives
show different trends depending on the nature of the donor
end groups or the core (PS versus PO). A slight enhance-
ment is obtained only for PO derivatives containing the
alkoxy donor end groups or the PS derivatives containing
the dialkyamino donor end groups. The second normaliza-
tion procedure based on the number of conjugated p-elec-
trons (Neff)[25] gives more precise information on the intrinsic
Branching Effect
To examine the effect of coupling between branches on
TPA responses, we have compared the response per sub-
chromophore (Figure 8) for all pairs of derivatives (three-
branched vs monomeric compound). In the case of phos-
phane oxides containing a PE2 connector, we observe that
the coupling with a common PO electron-withdrawing
moiety leads to a very slight enhancement of TPA response
following the trend observed for OPA. Hence, in the case of
such rigid compounds, the slight electronic coupling between
branches results in weak enhancement of both OPA and
TPA. In the case of phosphane oxide and sulfide derivatives
containing a PE–PV connector coupling leads instead to a
marked broadening of the TPA band and a consequent
small decrease in the peak TPA responses. This effect can
be related to the conformational flexibility of the PE–PV
linker.
effect of coupling between branches in phosphane oxide and
max
sulphide derivatives. As clearly shown in Table 3, the s2
/
Neff values are larger for the three-branched derivatives
except in the case of the sulfide derivative 5a, which is the
only derivative for which branching leads to a blueshift of
the low-energy absorption band. As was the case with other
normalization criteria, the PE2 linker leads to the steepest
effect, which confirms that the rigidity of the branches plays
an important role in promoting enhancement of the TPA re-
sponse in TPPO and TPPS three-branched derivatives.
Chem. Asian J. 2011, 6, 1080 – 1091
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1087

V. Michelet, I. Leray, M. Blanchard-Desce et al.
FULL PAPERS
of donating end groups or the conjugated linkers, whereas
stronger donor groups and PE–PV linkers allow the en-
hancement of TPA responses in a significant way. This study
thus opens a promising route towards new biphotonic envi-
ronment sensitive probes by the suitable combination of
donor end groups (powerful donor groups), acceptor TPPO
moieties, and conjugated linkers (elongated systems based
on PE–PV linkers) to ensure both highly environment-de-
pendent fluorescence and very large TPA responses. This is
of high interest for sensing in media for which endogenous
fluorophores or fluorescent contaminants are present. It
should be stressed that the modularity of synthesis allows
variation of the structure to modify the affinity/solubility of
such compounds.
Finally, coupling between branches leads to either a very
slight enhancement of TPA response per subchromophoric
unit (branch) or to broadening of the TPA band in the NIR
region and subsequent decrease in the peak TPA cross-sec-
tions. This study thus shows that TPPO and TPPS cores do
not promote major cooperative enhancement of the TPA re-
sponses, as was the case for branched octupolar derivatives
built from a common electron-donating triphenylamine core
(leading to the rise of an intense TPA band at higher
energy)[10–14,26–27] or from a common connecting benzene
moiety (leading to enhancement of the low-energy TPA
band),[28] but rather lead to TPA broadening. Such behavior
is closer to that reported for octupolar derivatives built from
a triphenylbenzene core,[15] which suggests that TPPO and
TPPS cores do not promote coherent coupling between
branches but instead through-space electrostatic interactions
between dipolar subchromophores are responsible for modi-
fications of the TPA responses of the branched phosphane
oxide and sulfide compounds.[29]
Experimental Section
~
^
Figure 8. TPA spectra of 1b/2b (top; =2b, =1b), 3b/4b (middle; & =
*
^
4b, =3b), and 5b/6b (bottom; +=6b, =5b) in chloroform.
Synthesis of Phosphane Derivatives
Reagents were commercially available from Acros and Aldrich and used
without further purification unless otherwise stated. Column chromatog-
raphy was performed with E. Merck 0.040–0.063 mm Art. 11567 silica
1
gel. H, 13C, and 31P NMR spectra were recorded on a Bruker AV 400 in-
Conclusions
strument. Chemical shifts were reported downfield from Me4Si (d=
0 ppm) for 1H and 13C spectroscopy, and H3PO4 was used as an internal
standard for 31P NMR spectroscopy. Coupling constants (J) are reported
in Hz and refer to apparent peak multiplicities. MS analyses were per-
formed at IMAGIF/ICSN and at the University P. et M. Curie. Com-
pounds 1–2, 8–9, and 8’ were prepared according to previously published
procedures.[3,5,6] Compounds 11 and 12 were also prepared according to
published procedures.[16,19]
New rod-shaped and three-branched derivatives formed by
the coupling of dipolar branches based on PE–PV conjugat-
ed linkers with a common PO or PS core have been pre-
pared and investigated. Photophysical studies show that all
compounds combine significant fluorescence and TPA re-
sponse in the NIR region. Time-resolved fluorescence decay
and solvatochromic studies indicate that excitation is local-
ized on one of the branches, leading to highly dipolar excit-
ed states. As a result, the chromophores behave as fluores-
cence polarity probes for polarity sensing. In addition, the
excited state polarity can be significantly enhanced by se-
lecting appropriate conjugated linkers and terminal moiet-
ies: stronger donating end groups, TTPS core, and more
rigid linkers lead to a greater sensitivity to polarity. In addi-
tion, OPA intensities are only weakly affected by the nature
Phosphane Oxide 3a
CuI (4 mg, 0.021 mmol) and [PdCl2ACHTNUGTRNEUNG(PPh3)2] (5 mg, 0.007 mmol) were
added to a solution of [(E)-1-iodo-4-(4-octyloxy)styryl]benzene (236 mg,
0.54 mmol), tris(4-ethynylphenyl)phosphane oxide (48 mg, 0.136 mmol)
in a mixture of toluene (5 mL), and diisopropylamine (3 mL). The result-
ing mixture was stirred for 15 h at 508C, then cooled to room tempera-
ture and concentrated under vacuum. The residue was purified by silica
gel chromatography (dichloromethane/methanol 98:2) to give the prod-
uct (147 mg, 85%). 1H NMR (400 MHz, CDCl3): d=7.60–7.70 (m, 12H;
ArH), 7.44–7.54 (m, 18H; ArH), 7.11 (d, 3H, J=16.0 Hz; HC=C), 6.96
1088
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Chem. Asian J. 2011, 6, 1080 – 1091

Phosphane Oxide and Sulfide Derivatives
(d, 3H, J=16.0 Hz; Hvin), 6.90 (d, 6H, J=8.7 Hz; ArH), 3.98 (t, 6H, J=
6.6 Hz), 1.79 (m, 6H), 1.40–1.50 (m, 6H), 1.25–1.40 (m, 24H), 0.89 ppm
(t, 9H, J=6.6 Hz); 13C NMR (100 MHz, CDCl3): d=159.4 (3C), 138.5
(3C), 132.2 (6C), 132.1 (d, J=10.5 Hz, 6C), 131.7 (d, J=12.4 Hz, 6C),
131.7 (d, 3C), 129.8 (3C), 129.7 (3C), 128.0 (6C), 127.7 (3C), 126.3 (6C),
125.7 (3C), 121.1 (3C), 114.9 (6C), 92.9 (3C), 89.2 (3C), 68.3 (3C), 32.0
(3C), 29.5 (3C), 29.4 (6C), 26.2 (3C), 22.8 (3C), 14.3 ppm (3C);
31P NMR (162 MHz, CDCl3): d=28.9 ppm; HRMS (ESI+): m/z: calcd
for C90H94O4P: 1269.6884; found: 1269.6937 [M+H]+.
(2C), 127.5 (C), 126.0 (2C), 124.1 (C), 122.7 (C), 120.2 (C), 111.7 (2C),
92.9 (C), 89.0 (C), 51.2 (2C), 32.0 (2C), 29.6 (2C), 29.5 (2C), 27.5 (2C),
22.8 (2C), 14.3 ppm (2C); 31P NMR (162 MHz, CDCl3): d=29.6 ppm;
HRMS (ESI+): m/z: calcd for C50H59NOP: 720.4328; found: 720.4347
[M+H]+.
Phosphane Sulfide 9’
Magnesium turnings (100 mg, 4.17 mmol) were placed in
Schlenk tube under argon. Distilled tetrahydrofuran (THF; 6 mL) and 4-
(bromophenylethynyl)trimethylsilane (992 mg, 4 mmol) were added
a 25 mL
5
Phosphane Oxide 4a
and the reaction was stirred overnight at room temperature. Chlorodi-
phenylphosphine (882 mg, 4 mmol) and distilled THF (2 mL) were
placed in a 50 mL Schlenk tube under argon at 08C. The solution of the
Grignard reagent was added dropwise over 15 min. The reaction mixture
was allowed to warm up to room temperature and stirred for 1 h. The so-
lution was then filtrated through a pad of silica with diisopropyl ether
(20 mL). The solvents are removed in vacuo, the oily residue is redis-
solved in distilled toluene (30 mL), and sulfur (172 mg, 6 mmol) is added.
The reaction mixture was heated to 1008C for 2 h. The solvents were re-
moved under vacuum and the residue was purified by silica gel chroma-
tography (petroleum ether/ethyl acetate 90:10) to give [4-(diphenylphos-
phinothioyl)phenylethynyl]trimethylsilane (450 mg, 1.15 mmol). The oily
product is placed in a 100 mL flask and redissolved in a mixture of di-
chloromethane (20 mL) and methanol (40 mL). Potassium carbonate
(159 mg, 1.15 mmol) was added and the reaction mixture was stirred at
room temperature for 1 h. The solvents were evaporated under vacuum
and the residue redissolved in diisopropyl ether (30 mL). Filtration
through a pad of silica and evaporation of the solvents gave the phos-
phane sulfide 7 (340 mg, 27%) as a yellow oil. 1H NMR (300 MHz,
CDCl3): d=7.65–7.75 (m, 6H; ArH), 7.40–7.55 (m, 9H; ArH), 3.20 ppm
(s, 1H; HCꢁC); 13C NMR (75 MHz, CDCl3): d=133.6 (d, J=85.2 Hz;
C), 132.5 (d, J=85.7 Hz; 2C), 132.2 (d, J=10.5 Hz; 4C), 132.1 (d, J=
7.2 Hz; C), 132.0 (d, J=8.8 Hz; 2C), 131.7 (d, J=2.8 Hz; C), 128.6 (d, J=
12.2 Hz; 4C), 125.5 (d, J=3.3 Hz; 2C), 81.9 (C), 79.3 ppm (C); 31P NMR
(121 MHz, CDCl3): d=43.2 ppm; HRMS (ESI+): m/z: calcd for
C20H15NaPS: 340.0524; found: 340.0525.
CuI (9 mg, 0.047 mmol) and [PdCl
added to a solution of [(E)-1-iodo-4-(4-octyloxy)styryl]benzene (273 mg,
0.628 mmol), diphenyl(4-ethynylphenyl)phosphane oxide (95 mg,
2ACHTNUGTREN(NNUG PPh3)2] (11 mg, 0.015 mmol) were
0.314 mmol) in a mixture of toluene (10 mL), and diisopropylamine
(5 mL). The resulting mixture was stirred for 15 h at 508C, then cooled to
room temperature and concentrated under vacuum. The residue was pu-
rified by silica gel chromatography (dichloromethane/methanol 98:2) to
give the product (151 mg, 79%). 1H NMR (400 MHz, CDCl3): d=7.54–
7.72 (m, 10H; ArH), 7.44–7.54 (m, 10H; ArH), 7.10 (d, 1H, J=16.0 Hz;
HC=C), 6.95 (d, 1H, J=16.0 Hz; HC=C), 6.89 (d, 2H, J=8.7 Hz; ArH),
3.98 (t, 2H, J=6.7 Hz), 1.79 (m, 2H), 1.45 (m, 2H), 1.20–1.40 (m, 8H),
0.89 ppm (t, 3H, J=6.9 Hz); 13C NMR (100 MHz, CDCl3): d=159.4 (C),
138.4 (C), 132.4 (d, J=103.9 Hz, 2C), 132.3 (d, J=103.9 Hz, C), 132.2 (d,
2C), 132.2 (2C), 132.1 (d, 4C), 132.1 (d, 2C), 131.5 (d, 2C), 129.7 (C),
129.7 (C), 128.7 (d, J=11.5 Hz, 4C), 128.0 (2C), 127.4 (C), 126.3 (2C),
125.7 (C), 121.1 (C), 114.9 (2C), 92.6 (C), 89.3 (C), 68.3 (C), 32.0 (C),
29.5 (C), 29.4 (2C), 26.2 (C), 22.8 (C), 14.3 ppm (C); 31P NMR
(162 MHz, CDCl3): d=29.6 ppm; HRMS (ESI+): m/z: calcd for
C42H42O2P: 609.2917; found: 609.2891 [M+H]+.
Phosphane Oxide 3b
CuI (4 mg, 0.021 mmol) and [PdCl2ACHTNUGTRNEUNG(PPh3)2] (5 mg, 0.007 mmol) were
added to a solution of (E)-4-(4-iodostyryl)-N,N-dioctylaniline (297 mg,
0.54 mmol), tris(4-ethynylphenyl)phosphane oxide (48 mg, 0.136 mmol)
in a mixture of toluene (5 mL), and diisopropylamine (3 mL). The result-
ing mixture was stirred for 15 h at 508C, then cooled to room tempera-
ture and concentrated under vacuum. The residue was purified by silica
gel chromatography (dichloromethane/methanol 98:2) to give the prod-
uct (192 mg, 88%). 1H NMR (400 MHz, CDCl3): d=7.61–7.78 (m, 12H;
ArH), 7.42–7.52 (m, 12H; ArH), 7.38 (d, 6H, J=8.7 Hz; ArH), 7.06 (d,
3H, J=16.0 Hz; HC=C), 6.85 (d, 3H, J=16.5 Hz; HC=C), 6.61 (d, 6H,
J=8.7 Hz; ArH), 3.28 (t, 12H, J=7.6 Hz), 1.59 (m, 12H), 1.20–1.35 (m,
60H), 0.89 ppm (t, 18H, J=6.6 Hz); 13C NMR (100 MHz, CDCl3): d=
148.1 (3C), 139.1 (3C), 132.2 (d, J=10.5 Hz; 6C), 132.1 (6C), 131.6 (d,
J=12.4 Hz; 6C), 131.4 (d, 3C), 130.4 (3C), 128.1 (6C), 127.8 (3C), 125.9
(6C), 124.0 (3C), 122.6 (3C), 120.1 (3C), 111.6 (6C), 93.1 (3C), 88.9
(3C), 51.1 (6C), 31.9 (6C), 29.6 (6C), 29.4 (6C), 27.4 (6C), 27.3 (6C),
22.8 (6C), 14.3 ppm (6C); 31P NMR (162 MHz, CDCl3): d=29.1 ppm;
HRMS (ESI+): m/z: calcd for C114H145N3OP: 1603.1119; found:
1603.1192 [M+H]+.
Phosphane Sulfide 5a
CuI (4 mg, 0.021 mmol) and [PdCl2ACHTNUGTRNEUNG(PPh3)2] (5 mg, 0.007 mmol) were
added to a solution of [(E)-1-iodo-4-(4-octyloxy)styryl]benzene (236 mg,
0.54 mmol), tris(4-ethynylphenyl)phosphane sulfide (50 mg, 0.136 mmol)
in a mixture of toluene (3 mL), and diisopropylamine (3 mL). The result-
ing mixture was stirred for 15 h at 508C, then cooled to room tempera-
ture and concentrated under vacuum. The residue was purified by silica
gel chromatography (cyclohexane/dichloromethane 6:5) to give the prod-
uct (125 mg, 71%). 1H NMR (300 MHz, CDCl3): d=0.89 (t, 9H, J=
7 Hz), 1.25–1.55 (m, 30H), 1.74–1.81 (m, 6H), 3.97 (t, 6H, J=7 Hz), 6.89
(d, 12H, J=8.6 Hz), 6.95 (d, 3H, J=16 Hz), 7.10 (d, 3H, J=16 Hz),
7.41–7.53 (m, 16H), 7.59–7.79 ppm (m, 8H); 13C NMR (75 MHz, CDCl3):
d=159.4 (3C), 138.4 (3C), 137.8 (3C), 132.5 (6C), 132.4 (d, J=10.4 Hz,
6C), 132.2 (6C) , 131.7 (6C), 129;7 (3C), 128.6 (d, J=12.6 Hz, 6C), 128.0
(3C), 126.3 (3C), 125.6 (3C), 121.0 (3C), 114.9 (6C), 92.9 (3C), 89.2
(3C), 68.2 (6C), 31.9 (6C), 29.8 (6C), 29.5 (6C), 29.4 (6C), 26.2 (6C),
22.8 (6C), 14.3 ppm (6C); 31P NMR (121 MHz, CDCl3): d=42.75 ppm;
HRMS (MALDI-TOF): m/z: calcd for C90H94O3PS: 1285.65; found:
1285.65 [M+H]+.
Phosphane Oxide 4b
CuI (9 mg, 0.047 mmol) and [PdCl
added to a solution of (E)-4-(4-iodostyryl)-N,N-dioctylaniline (343 mg,
0.628 mmol), diphenyl(4-ethynylphenyl)phosphane oxide (95 mg,
2ACHTNUGTREN(NNUG PPh3)2] (11 mg, 0.015 mmol) were
0.314 mmol) in a mixture of toluene (10 mL), and diisopropylamine
(5 mL). The resulting mixture was stirred for 15 h at 508C, then cooled to
room temperature and concentrated under vacuum. The residue was pu-
rified by silica gel chromatography (dichloromethane/methanol 99:1) to
give the product (188 mg, 84%). 1H NMR (400 MHz, CDCl3): d=7.53–
7.72 (m, 10H; ArH), 7.42–7.53 (m, 8H; ArH), 7.38 (d, 2H, J=9.2 Hz;
ArH), 7.07 (d, 1H, J=16.5 Hz; HC=C), 6.85 (d, 1H, J=16.5 Hz; HC=C),
6.61 (d, 2H, J=9.2 Hz; ArH), 3.28 (t, 4H, J=7.6 Hz), 1.59 (m, 4H),
1.20–1.40 (m, 20H), 0.89 ppm (t, 6H, J=6.9 Hz); 13C NMR (100 MHz,
CDCl3): d=148.2 (C), 139.2 (C), 132.4 (d, J=103.9 Hz, 2C), 132.2 (d,
4C), 132.2 (d, 2C), 132.1 (2C), 132.1 (d, 2C), 132.0 (d, J=103.9 Hz, C),
131.5 (d, J=12.4 Hz, 2C), 130.4 (C), 128.7 (d, J=12.4 Hz, 4C), 128.2
Phosphane Sulfide 5b
CuI (4 mg, 0.021 mmol) and [PdCl2ACHTNUGTRNEUNG(PPh3)2] (5 mg, 0.007 mmol) were
added to a solution of (E)-4-(4-iodostyryl)-N,N-dioctylaniline (297 mg,
0.544 mmol), tris(4-ethynylphenyl)phosphane sulfide (50 mg, 0.136 mmol)
in a mixture of toluene (3 mL), and diisopropylamine (3 mL). The result-
ing mixture was stirred at 508C for 15 h, then cooled to room tempera-
ture and concentrated under vacuum. The residue was purified by silica
gel chromatography (cyclohexane/dichloromethane 6:4) to give the prod-
uct (121 mg, 63%). 1H NMR (300 MHz, CDCl3): d=0.88 (t, 18H, J=
7 Hz), 1.28–1.31 (m, 48H), 1.55–1.58 (m, 24H), 3.27 (t, 12H, J=7 Hz),
6.61 (d, 12H, J=9 Hz), 6.85 (d, 3H, J=16 Hz), 7.08 (d, 3H, J=16 Hz),
Chem. Asian J. 2011, 6, 1080 – 1091
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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V. Michelet, I. Leray, M. Blanchard-Desce et al.
FULL PAPERS
7.36–7.46 (m, 16H), 7.48–7.73 ppm (m, 8H); 13C NMR (75 MHz, CDCl3):
d=148.2 (3C), 139.1 (3C), 133.3 (6C), 132.9 (3C), 132.4 (d, J=10.5 Hz,
6C), 132.3 (6C), 132.2 (6C), 132.1 (6C),131.4 (d, J=12.3 Hz, 6C) 131.2
(3C), 130.3 (3C), 128.2 (6C), 127.7 (3C), 125.8 (6C), 124.3 (3C), 122.5
(3C), 120.3 (3C), 111.5 (6C), 92.9 (6C),51.2 (6C), 31.9 (6C), 29.9 (6C),
29.4 (6C), 27.4 (6C), 27.3 (6C), 22.8 (6C), 14.2 ppm (6C);31P NMR
(121 MHz, CDCl3): d=42.7 ppm; HRMS (MALDI-TOF): m/z: calcd for
C114H145N3PS: 1619.97; found 1619.97 [M+H]+
mamatsu MCP R3809U photomultiplier, connected to a constant fraction
discriminator. The time-to-amplitude converter was purchased from Ten-
nelec. Data were analyzed by a nonlinear least-squares method by using
Globals software (Globals Unlimited, University of Illinois at Urbana-
Champaign, Laboratory of Fluorescence Dynamics).
Two-Photon Absorption Experiments
TPA spectra were obtained by measuring the TPEF (two-photon excited
fluorescence) according to the well-established method described by Xu
and Webb[31] and the appropriate solvent-related refractive index correc-
tions.[32] TPEF cross-sections were measured relative to fluorescein in
0.01m aqueous NaOH for 715–980 nm.[31,33]. Data points between 700 and
715 nm were corrected according to reference.[34] A mode-locked Ti:sap-
phire laser generating 150 fs wide pulses at a rate of 76 MHz, with a
time-averaged power of several hundreds of mW (Coherent Mira 900
pumped by a 5 W Verdi) was used as the excitation source. The excitation
was focused into the cuvette through a microscope objective (10ꢃ, NA
0.25). The fluorescence was detected in epifluorescence mode by a di-
chroic mirror (Chroma 675dcxru) and a barrier filter (Chroma e650sp-
2p) by a compact CCD spectrometer module BWTek BTC112E. Total
fluorescence intensities were obtained by integrating the corrected emis-
sion spectra measured by this spectrometer.TPA cross-sections (s2) were
determined from the two-photon excited fluorescence (TPEF) cross-sec-
tions (s2F) and the fluorescence emission quantum yield (F).
Phosphane Sulfide 6a
CuI (9 mg, 0.047 mmol) and [PdCl2ACHTNUGRTNEUNG(PPh3)2] (11 mg, 0.015 mmol) were
added to a solution of [(E)-1-iodo-4-(4-octyloxy)styryl]benzene (273 mg,
0.629 mmol), diphenyl(4-ethynylphenyl)phosphane sulfide (100 mg,
0.314 mmol) in
a mixture of toluene (5 mL), and diisopropylamine
(3 mL). The resulting mixture was stirred for 15 h at 508C, then cooled to
room temperature and concentrated under vacuum. The residue was pu-
rified by silica gel chromatography (cyclohexane/dichloromethane 6:5) to
1
give the product (135 mg, 70%). H NMR (300 MHz, CDCl3): d=0.89 (t,
3H, J=7 Hz), 1.29–1.32 (m, 10H), 1.55–1.58 (m, 2H), 3.97 (t, 2H, J=
7 Hz), 6.89 (d, 4H, J=8.8 Hz), 6.95 (d, 1H, J=16 Hz), 7.10 (d, 1H, J=
16 Hz), 7.43–7.60 (m, 10H), 7.66–7.74 ppm (m, 8H); 13C NMR (75 MHz,
CDCl3): d=159.3 (C), 138.4 (C), 132.4 (d, J=10.5 Hz, 2C) 132.3 (2C),
132.2 (2C), 131.9 (2C), 131.6 (2C), 131.4 (2C), 129.7 (C), 128.8 (d, J=
12 Hz, 2C), 128.0 (2C), 126.9 (2C), 125.6 (C), 121.1 (C), 114.8 (2C), 92.6
(C), 89.2 (C), 51.2 (C), 31.9 (C), 29.6 (C), 29.4 (C), 27.4 (C), 27.3 (C),
22.8 (C), 14.2 ppm (C); 31P NMR (121 MHz, CDCl3): d=43.22 ppm;
HRMS (ESI+): m/z: calcd for C42H42OPS: 625.2616; found: 625.2603
[M+H]+.
Acknowledgements
Phosphane Sulfide 6b
We are grateful to A. Brosseau for his assistance in tuning the single-
photon timing instruments. We thank Dr. O. Mongin for helpful discus-
sions. This work was supported by the French Agence Nationale pour la
Recherche (grant no. ANR-08-CP2D-11). Rꢀgion Bretagne is gratefully
acknowledged for a fellowship to C.R.
CuI (9 mg, 0.047 mmol) and [PdCl2ACHTNUGRTNEUNG(PPh3)2] (11 mg, 0.015 mmol) were
added to a solution of (E)-4-(4-iodostyryl)-N,N-dioctylaniline (342 mg,
0.628 mmol), diphenyl(4-ethynylphenyl)phosphane sulfide (100 mg,
0.314 mmol) in
a mixture of toluene (5 mL), and diisopropylamine
(3 mL). The resulting mixture was stirred at 508C for 15 h, then cooled
to room temperature and concentrated under vacuum. The residue was
purified by silica gel chromatography (cyclohexane/dichloromethane 7:3)
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1
to give the product (150 mg, 65%). H NMR (300 MHz, CDCl3): d=0.90
(t, 6H, J=7 Hz), 1.29–1.32 (m, 20H), 1.55–1.58 (m, 4H), 3.28 (t, 4H, J=
7 Hz), 6.62 (d, 4H, J=9 Hz), 6.85 (d, 1H, J=16 Hz), 7.08 (d, 1H, J=
16 Hz), 7.37–7.67 (m, 10H), 7.70–7.77 ppm (m, 8H); 13C NMR (75 MHz,
CDCl3): d=148.2 (C), 139.1 (C), 133.4 (C), 132.4 (d, J=10.4 Hz, 3C),
132.3 (6C), 132.2 (2C), 132.1 (2C), 131.8 (2C), 131.6 (2C), 131.4 (2C),
130.4 (3C), 128.9 (C), 128.7 (d, J=12 Hz, 2C), 128.1 (2C), 125.5 (2C),
124.1 (C), 122.7 (2C), 120.2 (C), 111.6 (2C), 92.9 (C), 88.9 (C), 51.2 (2C),
31.9 (2C), 29.6 (2C), 29.4 (2C), 27.4 (2C), 27.3 (2C), 22.8 (2C),
14.2 ppm (2C); 31P NMR (121 MHz, CDCl3): d=43.22 ppm; HRMS
(ESI+): m/z: calcd for C50H59NPS: 736.4028; found: 736.4008 [M+H]+.
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Received: September 20, 2010
Published online: February 16, 2011
Chem. Asian J. 2011, 6, 1080 – 1091
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1091