Synthesis, fluorescence, and two-photon absorption of a series of elongated rodlike and banana-shaped quadrupolar fluorophores: A comprehensive study of structure-property relationships

Article abstract of DOI:10.1002/chem.200600689

An extensive series of push-push and pull-pull derivatives was prepared from the symmetrical functionalization of an ambivalent core with conjugated rods made from arylene-vinylene or arylene-ethynylene building blocks, bearing different acceptor or donor

Full text of DOI:10.1002/chem.200600689

FULL PAPER
DOI: 10.1002/chem.200600689
Synthesis, Fluorescence, and Two-Photon Absorption of a Series of
Elongated Rodlike and Banana-Shaped Quadrupolar Fluorophores:
A Comprehensive Study of Structure–Property Relationships
Olivier Mongin,* Laurent Porr›s, Marina Charlot, Claudine Katan, and
Mireille Blanchard-Desce*[a]
Abstract: An extensive series of push–
push and pull–pull derivatives was pre-
pared from the symmetrical functional-
ization of an ambivalent core with con-
jugated rods made from arylene–vinyl-
ene or arylene–ethynylene building
blocks, bearing different acceptor or
donor end-groups. Their absorption
and photoluminescence, as well as their
two-photon-absorption (TPA) proper-
ties in the near infrared (NIR) region,
were systematically investigated to
derive structure–property relationships
and to lay the guidelines for both spec-
tral tuning and amplification of molec-
ular TPA in the target region. Whatev-
er the nature of the core or of the con-
nectors, push–push systems were found
to be more efficient than pull–pull sys-
tems, and planarization of the core
(fluorene versus biphenyl) always leads
to an increase in the TPA cross sec-
tions. In contrast, increasing the conju-
gation length as well as replacement of
a phenylene moiety by a thienylene
moiety in the conjugated rods did not
necessarily lead to increased TPA re-
sponses. The present study also demon-
strated that the topology of the conju-
gated rods can dramatically influence
the TPA properties. This is of particu-
lar interest in terms of molecular engi-
neering for specific applications, as
both TPA properties and photolumi-
nescence characteristics can be consid-
erably affected. Thus, it becomes possi-
ble to optimize the transparency/TPA
and fluorescence/TPA efficiency trade-
offs for optical limiting in the red-NIR
region (700–900 nm) and for two-
photon-excited fluorescence (TPEF)
microscopy applications, respectively.
Keywords: chromophores · fluores-
cence · nonlinear optics · photolu-
minescence · two-photon absorp-
tion
Introduction
widespread popularity in the biology community and has
given rise to the technique of two-photon laser scanning
fluorescence microscopy,[14–16] which enables, for instance, in
vivo imaging of calcium dynamics[17,19–21] or intracellular
zinc.[22,23] Use of a two-photon-excitation process (i.e., a
nonlinear process involving the simultaneous absorption of
two photons) instead of a conventional one-photon excita-
tion actually offers a number of advantages. These include
the ability for a highly confined excitation and intrinsic
three-dimensional resolution in microscopic imaging. More-
over, by replacing one-photon excitation in the UV-visible
blue region by two-photon excitation in the visible red-NIR
region (typically 700–1200 nm), TPEF offers the advantage
of imaging at an increased penetration depth in tissues
(owing in particular to a reduction of scattering losses) with
reduced photodamage, as well as improved signal-to-noise
ratio (owing to reduced background fluorescence). The fast
development of TPEF microscopy has triggered the search
for novel fluorophores specifically engineered for TPEF.
Fluorophores with TPA cross sections many orders of mag-
Molecular two-photon absorption (TPA) has attracted grow-
ing interest over recent years owing to its applications in
various fields such as spectroscopy,[1,2] three-dimensional op-
tical data storage,[3–7] microfabrication,[8–11] laser up-conver-
sion,[12,13] high-resolution three-dimensional imaging of bio-
logical systems,[14–17] and photodynamic therapy.[18] Among
these, two-photon-excited fluorescence (TPEF) has gained
[a]Dr. O. Mongin, Dr. L. Porr›s, Dr. M. Charlot, Dr. C. Katan,
Dr. M. Blanchard-Desce
Synth›se et ElectroSynth›se Organiques (CNRS, UMR 6510)
Institut de Chimie, UniversitØ de Rennes 1
Campus Scientifique de Beaulieu, Bât 10A
35042 Rennes Cedex (France)
Fax : (+33)223-236-955
E-mail: olivier.mongin@univ-rennes1.fr
mireille.blanchard-desce@univ-rennes1.fr
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
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nitude larger than endogenous fluorophores (such as fluo-
rescent amino acids, flavins)[24–26] are attractive for reducing
background fluorescence by selective two-photon-excitation
of TPEF probes. In addition, TPEF fluorophores with both
broad and intense TPA bands are also of interest because of
the versatility they offer in terms of excitation sources (inso-
far as costly, tunable short-pulse lasers can be replaced by
less-expensive, nontunable laser sources).
Multiphoton absorption has also attracted considerable
attention for optical limiting,[27–39] focusing mainly on optical
limiting in the visible region aiming at eye protection.[37–39]
Although a number of multiphoton chromophores have
been designed and studied in this context, only scarce effort
has been dedicated to the protection of near infrared (NIR)
detectors typically working in the 700–900 nm region. Thus,
chromophores combining full transparency and strong multi-
photon absorptivities (such as overlapping of strong two-
photon and excited-state absorptions) in that spectral range
are required.
Within this context, we have implemented a molecular-en-
gineering approach towards elongated rodlike or banana-
shaped fluorophores with enhanced TPA cross sections (s2)
in the target spectral window (i.e., 700–1000 nm).[40] A high
fluorescence quantum yield (F) is required for TPEF appli-
cations, whereas a full linear transparency is required for op-
tical-limiting applications. Here, we describe and discuss
their molecular design, synthesis, photophysical and TPA
properties. A wide scope of molecules was prepared and in-
vestigated to derive structure–property relationships and to
lay the guidelines for both spectral tuning of both absorp-
tion and fluorescence and amplification of molecular TPA.
By following the route for molecular TPA optimization
proposed by Marder and collaborators,[41,42] we focused on
the optimization of quasi-one-dimensional quadrupolar sys-
tems, that is, symmetrical conjugated molecules bearing two
electron-releasing (D) or electron-withdrawing (A) end-
groups.[40,43–45] Indeed, quadrupolar systems[27,30,35,39–79] have
been found to be more efficient than push–pull sys-
tems[13,28,46,47,56,64,68,80–88] in terms of TPA, in particular for
multiphoton-based optical-limiting applications.[27,30,39] Such
derivatives can display very large TPA cross sections in con-
nection with a quadrupolar intramolecular charge transfer
taking place between the ends and the center of the mole-
cules.[42] Very large s2 values have been obtained with
DAAD, ADDA, DADAD, DDADD··· systems having
strong D and A moieties, but often at the cost of reduced
fluorescence quantum yield and/or pronounced red-shift of
the one-photon-absorption band.[41,77] In this context, our
purpose was the design of optimized systems displaying en-
hanced s2 values in the red-NIR region (700–1000 nm),
while maintaining high fluorescence quantum yields. Our
strategy, founded on a three-VB-state model,[89–91] was based
on the push–push or pull–pull functionalization of a semirig-
id, conjugated system.[40,43–45]
The structure was built from the symmetrical grafting,
onto a conjugated core, of two elongated conjugated rods
bearing either a D or A end-group (Figure 1). The central
building blocks were selected as more or less rigid units that
may assist quadrupolar intramolecular charge transfer by
acting either as a (weak) donor or acceptor core. We select-
ed biphenyl (BP) or fluorene (Fl) central units, which allow
the tuning of the electronic delocalization along the conju-
gated backbone in the ground state by modulation of the
twist angle between the two halves of the molecules.[40] It
should be noted that the fluorene building block was suc-
cessfully used in the design of both dipolar[46,83] and quadru-
polar systems with large multiphoton absorption,[40,59,69]
owing to the planarity it provides. Conjugated rods built
Figure 1. Molecular engineering of pull–pull and push–push fluorophores designed for TPEF (Non=nonyl).
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Quadrupolar Fluorophores
FULL PAPER
from arylene–ethynylene and/or arylene–vinylene oligomers
were investigated to maintain fluorescence and to modulate
the electronic communication between the end-groups and
the core of the molecules. The aim of these systematic struc-
tural variations was both to derive comprehensive structure–
TPA relationships and to ascertain the appropriate combina-
tion of core, linker (double versus triple bond), and connec-
tor (phenylene P, thienylene T, furylene F, fluorenylene Fl)
moieties for optimized TPA/luminescence and/or TPA/trans-
parency properties. Long alkyl chains were grafted onto the
peripheral groups and/or onto the core to obtain highly solu-
ble derivatives, which are required for optical-limiting appli-
cations. Moreover, the central nonyl chains on the fluorenyl
core were intended to hinder p stacking and aggregation
processes that are detrimental to TPA[79] and photolumines-
cence properties.
Results and Discussion
Scheme 1. a) 2-methyl-3-butyn-2-ol, [Pd
(82%); b) NaOH, toluene/iPrOH, reflux, 1 h (87%); c) 1d (1 equiv), 1,4-
diiodobenzene (3 equiv), [Pd(PPh3)2Cl2], CuI, toluene/Et3N, 30 8C, 6 h
(71% of 2a); d) 1d (1 equiv), 4-bromobenzaldehyde (1.2 equiv), [Pd-
(PPh3)2Cl2], CuI, toluene/Et3N, 40 8C, 15 h (74% of 2b); e) 3c, 4-iodo-
benzaldehyde, tBuOK, CH2Cl2, 208C, 5 h, then I2 cat., hn (85% of 4a);
f) 3b, terephthalaldehyde mono(diethylacetal), tBuOK, CH2Cl2, 208C,
24 h; HCl, 208C, 1 h; I2 cat., hn (84% of 4b); g) 3b or 3c, conditions as
in (f) (95% of 6a, 79% of 6b, 85% of 6c). Bu=butyl, Hex=hexyl;
Oct=octyl.
A
Synthesis: The assembly of cores, linkers, and end-groups
was performed by means of Sonogashira or Heck couplings
and Wittig or Horner–Wadsworth–Emmons condensations.
Amino (1a) and dialkylamino (1b)[92] moieties bearing an
iodo group were used as electron-releasing building blocks,
and 1b was also converted to the extended rigid moieties 2a
and 2b in three-step sequences: 1) palladium(II)-catalyzed
reaction with 2-methyl-3-butyn-2-ol, 2) base-promoted de-
protection, and 3) cross-coupling with 1,4-diiodobenzene
and 4-bromobenzaldehyde, respectively (Scheme 1). Other
electron-donating dialkylamino building blocks were pre-
pared, bearing either a formyl (1e)[93] or a phosphonium
(3a–c)[94] group. Phosphonium salts 3b and 3c were also
converted to the semirigid stilbene rods 4b and 4a, respec-
tively, through their Wittig condensation with terephthalal-
dehyde mono(diethylacetal) and 4-iodobenzaldehyde, re-
spectively. The furylene–vinylene- and thienylene–vinylene-
containing building blocks 6a–c were obtained by reaction
of 2,5-furanedicarboxaldehyde monoacetal (5a)[95] or 2,5-
AHCTREUNG
AHCTREUNG
thio
phenedicarboxaldehyde monoacetal (5b)[96] with phos-
A
phonium salts 3b or 3c, followed by acidic hydrolysis of the
intermediate acetals (Scheme 1).
Scheme 2. a) 7a, H2O2, Na2WO4·2H2O cat., EtOH, reflux, 1 h (93% of
8a); b) 7b, H2O2, AcOH, reflux, 3 h (89% of 8b); c) HC=CSiMe3, [Pd-
The electron-withdrawing alkylsulfone 8a was prepared
by oxidation of thioether 7a,[97] and the trifluoromethylsul-
fone 8d was obtained from 7b in a three-step sequence, in-
volving oxidation, palladium(II)-catalyzed reaction with
ethynyltrimethylsilane, and cleavage of the trimethylsilyl
group. Phosphonates 9a[98] and 9b, as well as phenylene–vi-
nylene-extended phosphonate 11,[99] were also used as elec-
tron-withdrawing moieties. The halogen-bearing sulfone 10
was obtained from a Horner–Wadsworth–Emmons conden-
sation between 9b and 4-iodobenzaldehyde (Scheme 2).
The synthesis of the biphenyl-cored fluorophores 13a,
13b, and 14 was achieved by means of a double Sonogashira
coupling of 12[100] with 1b, 2a, and 4a, respectively
(Scheme 3). Bisphosphonate 15b (prepared by Michaelis–
Arbusov reaction of 4,4’-bis(bromomethyl)-1,1’-biphenyl
A
ride (TBAF), THF (64%); e) 9b, 4-iodobenzaldehyde, NaH, THF, 208C,
15 h (61%).
(15a)[101] with triethylphosphite) was used to prepare the
other biphenyl-cored fluorophores 16a, 16b, 17a, and 17b,
by condensation with aldehydes 1e, 2b, 6a, and 6c, respec-
tively (Scheme 3).
The fluorene core 18d was obtained from 9,9-dinonyl-
fluorene (18a) in a three-step sequence: 1) diiodination,
2) cross-coupling with 2-methyl-3-butyn-2-ol, and 3) base-
promoted deprotection (Scheme 4). Double Sonogashira
coupling of 18d with 1b, 2a, and 4a afforded push–push
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M. Blanchard-Desce, O. Mongin et al.
Scheme 3. a) 1b (2.3 equiv), [Pd
(a), 3.5 h (81%); d) P(OEt)3, toluene, reflux, 60 h (86%); e) 1e (2 equiv), NaH, THF, 208C, 20 h, then reflux, 4 h (70% of 16a); f) 2b (2.3 equiv), NaH,
THF, [18]crown-6 cat., 408C, 3 h (84% of 16b); g) 6a or 6c (2.1 equiv), NaH, THF, 208C, 16–19 h (80% of 17a, 64% of 17b).
(PPh3)2Cl2], CuI, toluene/Et3N, 20 8C, 2 h (84% of 13a); b) 2a, conditions as in (a) (86% of 13b); c) 4a, conditions as in
ACHTREUNG
Scheme 4. a) I2, H5IO6, AcOH, H2SO4, H2O, 75 8C, 2 h (69%); b) 2-methyl-3-butyn-2-ol, [Pd
A
iPrOH, reflux, 0.5 h (88%); d) 1b (2.4 equiv), [Pd(PPh3)2Cl2], CuI, toluene/Et3N, 20 8C, 3 h (45% of 19a); e) 2a, conditions as in (d), 20 h (82% of 19b);
AHCTREUNG
f) 4a, conditions as in (d), 15 h (83%); g) 8a, conditions as in (d), 458C, 6 h (84% of 21a); h) 18b, 8d (2.5 equiv), conditions as in (d), 408C, 14 h (60%
of 21b); i) 10, conditions as in (d), 358C, 14 h (87% of 21c).
molecules 19a, 19b, and 20, respectively, whereas reaction
with 8a and 10 gave pull–pull molecules 21a and 21c, re-
spectively. The bistrifluoromethylsulfone 21b was obtained
by reacting the diiodo-fluorene core 18b and the alkyne 8d
(Scheme 4).
The bisaldehyde core 22b was also obtained from 9,9-di-
nonylfluorene (18a), by successive dibromination, double
bromine–lithium exchange, and formylation reactions
(Scheme 5). Wittig condensation of bisaldehyde 22b with
two equivalents of 4-(methoxybenzyl)triphenylphosphonium
bromide gave (after isomerization with a catalytic amount
of iodine under illumination) fluorophore 23, whereas the
same reaction with one single equivalent of phosphonium
salt 3a lead to the formation of fluorophore 24 together
with the new extended building block 25. Vinylic bissulfones
26a and 26b were synthesized by a double Horner–Wads-
worth–Emmons condensation of the same bisaldehyde 22b
with phosphonates 9a and 11, respectively (Scheme 5).
The bisvinyl fluorene core 27, obtained by condensation
of 22b with methyltriphenylphosphonium iodide, was react-
ed with 4-iodoaniline 1a to afford fluorophore 28, by means
of a double Heck-type coupling under Jefferyꢁs[102] condi-
tions (Scheme 6).
Conversion of 22b to the fluorenebisphosphonate 29c was
achieved in a three-step sequence (reduction, bromination,
and Michaelis–Arbusov reaction). Finally, this new fluorene
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Quadrupolar Fluorophores
FULL PAPER
Scheme 5. a) Br2 (2 equiv), CH2Cl2, 208C, 15 h (97%); b) nBuLi, benzene, 608C, 4 h, then N-formylpiperidine, 208C, 14 h (48%); c) 4-(methoxybenzyl)-
triphenylphosphonium bromide (2.2 equiv), tBuOK, CH2Cl2, 208C, 48 h, then I2 cat., hn (75%); d) 3a (1.0 equiv), tBuOK, CH2Cl2, 208C, 16 h, then I2
cat., hn (12% of 24, 59% of 25); e) 9a (2.2 equiv), NaH, THF, 208C, 16 h (95% of 26a); f) 11, conditions as in (e) (63% of 26b).
{[5-(1-piperidinyl)-2-thienyl]-
methyl}triphenylphosphonium
iodide (Scheme 8).
All new fluorophores were
fully characterized by NMR
spectroscopy, HRMS, and/or
1
elemental analysis. The H and
Scheme 6. a) Methyltriphenylphosphonium iodide (2.5 equiv), NaH, THF, 208C, 48 h (63%); b) 1a
(2.5 equiv),[Pd(OAc)2], PPh3, nBu4NCl, K2CO3, DMF, 908C, 22 h (56%).
ACHTREUNG
13C NMR spectra confirm their
high symmetry. In addition,
their all-E stereochemistry was
core was reacted with aldehydes 4b, 6b, and 25 in the pres-
ence of sodium hydride to give phenylene–vinylene-linked
fluorophore 30, its thienylene–vinylene analogue 31, and the
trimeric fluorenylene–vinylene 32, respectively (Scheme 7).
Finally, the bisaldehyde core 22b and its thienylene–vinyl-
ene-extended analogue 33, obtained by reaction of bis-
derived from the values of the 3J coupling constants between
vinylic protons (J~16 Hz). All the dinonylfluorene deriva-
tives are extremely soluble in chlorinated solvents (typically
higher than 500 gLꢀ1) as well as in THF and toluene, where-
as the extended biphenyl fluorophores (13b, 14, 16b) exhibit
much lower solubilities (1–5 gLꢀ1). Long alkyl chains locat-
ed on the central cores are more efficient in increasing the
solubility than those located on the peripheral groups.
ACHTREUNG
Scheme 7. a) KBH4, EtOH/CH2Cl2, 208C, 14 h (97%); b) concd HBr, reflux, 3 h (90%); c) P
A
208C, 20 h (53%); e) 6b (2.5 equiv), NaH, THF, [18]crown-6 cat., reflux, 7 h (68%); f) 25 (2.2 equiv), NaH, THF, 208C, 16 h (84%).
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M. Blanchard-Desce, O. Mongin et al.
Scheme 8. a) 5b (2.3 equiv), NaH, THF, 208C, 15 h, then 608C, 2 h; HCl, 208C, 2 h (55%); b) 22b, {[5-(1-piperidinyl)-2-thienyl]methyl}triphenylphospho-
nium iodide (2.3 equiv), tBuOK, CH2Cl2, 208C, 48 h, then I2 cat., hn (22% of 34a); c) 33, conditions as in (b) (18% of 34b).
Moreover, the latter are unnecessary if nonyl chains are
present on the core, as exemplified with methylsulfonyl de-
rivatives 26a,b, the solubility of which is quite similar to
that of the other dinonylfluorene derivatives.
molecules exhibit good fluorescence quantum yields, ranging
between 0.45 and 0.98.
Core effect: Substitution of the biphenyl core by a fluorene
core produces a systematic red-shift of the absorption band
while maintaining quasiidentical fluorescence properties
(Supporting Information, Figure S1). Thus, the resulting
Stokes shift is consistently reduced. Moreover, except for
compounds 14 and 20, the halfbandwidth of fluorenyl deriv-
atives is systematically smaller than that of its biphenyl ana-
logue. In fact, these distinctive features are directly related
to geometrical properties: although the fluorene core is al-
ready planar in the ground state, the biphenyl unit has some
torsional flexibility, the lowest-energy conformation corre-
sponding to a twist angle of about 358.[73] This leads to both
blue-shift and broadening of the absorption band of biphen-
yl derivatives in contrast to fluorene analogues. The similari-
Absorption and photoluminescence properties: The photo-
physical properties (absorption and fluorescence) of the new
series of fluorophores are collected in Table 1 and include
fluorescence quantum yields and lifetimes. Corresponding
figures are given as Supporting Information. We observe
that all fluorophores display an intense absorption in the
near UV-visible blue region, with typical molar extinction
coefficients ranging from 60,000–180,000 molꢀ1 Lcmꢀ1. Their
absorption and emission range can be tuned by playing on
the nature of the end-groups, of the core moiety, and on the
nature and length of the conjugated rods. In addition, all
Table 1. Photophysical properties of quadrupolar compounds in toluene.
abs
max
em
max
Compound
Length
[nm]
l
logemax
FWHM
[cmꢀ1
l
Stokes shift
[cmꢀ1
F[a]
t[b]
[nm]
G
]
[nm]
H
]
[ns]
Name
End-group
Linker
Core
13a
16a
13b
14
16b
17a
17b
NHex2
NHex2
NHex2
NOct2
NHex2
NOct2
NHex2
PE
PV
PE2
PV–PE
PE–PV
PV–FV
PV–TV
BP
BP
BP
BP
BP
BP
BP
2.4
2.3
3.8
3.7
3.7
3.5
3.6
374
401
381
406
400
443
458
4.92
4.92
5.03
5.13
5.22
5.13
5.10
3800
3900
4250
3600
3950
4400
3900
424
456
433
463
452
522
522
3200
3000
3200
3000
2900
3400
2700
0.90
0.84
0.82
0.50
0.81
0.69
0.51
0.70
0.82
0.73
0.74
0.79
1.25
0.85
19a
23
28
NHex2
OMe
NH2
NBu2
Pip
NHex2
NHex2
NOct2
NBu2
NOct2
Pip
PE
PV
PV
PV
TV
PE2
PV2
PV–PE
PV–FlV
PV–TV
TV2
FL
FL
FL
FL
FL
FL
FL
FL
FL
FL
FL
2.4
2.3
2.3
2.3
2.2
3.8
3.6
3.7
4.5
3.5
3.5
387
381
392
415
387
387
431
411
429
470
451
4.92
4.82
4.87
4.98
4.78
5.11
5.13
5.10
5.26
5.09
4.98
3700
3900
4000
3600
3900
4100
4000
4300
3700
3800
3900
421
415
433
457
484
433
480
464
472
525
540
2100
2200
2400
2200
5200
2700
2400
2800
2100
2200
3600
0.80
0.90
0.82
0.79
0.45
0.82
0.85
0.61
0.78
0.47
0.45
0.74
0.87
0.83
0.87
1.00
0.60
0.83
0.80
0.73
0.79
0.67
24
34a
19b
30
20
32
31
34b
21b
21a
26a
21c
26b
SO2CF3
SO2Oct
SO2Me
SO2Oct
SO2Me
PE
PE
PV
PV–PE
PV2
FL
FL
FL
FL
FL
2.4
2.4
2.3
3.7
3.7
372
363
387
382
412
4.84
4.86
4.82
5.08
4.91
3900
3500
3600
4500
4000
404
389
423
419
456
2200
1800
2200
2300
2300
0.98
0.76
0.91
0.90
0.73
0.79
0.64
0.87
0.56
0.74
[a]Fluorescence quantum yield determined relative to fluorescein in 0.1 m NaOH. [b]Fluorescence lifetime determined by using time-correlated single-
photon counting (TCSPC).
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Quadrupolar Fluorophores
FULL PAPER
ties of the emission properties clearly demonstrate that the
biphenyl core becomes planar in the relaxed emitting excit-
ed state.
other photoluminescence characteristics are differently af-
fected, depending on the nature of the connector. If the
length is increased by doubling the same connector (Sup-
porting Information, Figure S4, Table 1), absorption bands
undergo a broadening and emission bands are red-shifted.
Because the hyperchromic effect tends to increase the radia-
tive decay, whereas the emission red-shift has an opposite
effect, the fluorescence quantum yields increase (compound
30 versus 24) if the former effect dominates, whereas the op-
posite is observed if the latter dominates (compound 26b
versus 26a). In the case of thienylene–vinylene oligomers,
increasing the number of thienylene–vinylene units leads to
the largest red-shifts of both the absorption and emission
bands, as well as to a hyperchromic effect of the absorption
band (Supporting Information, Figure S4b). The fluores-
cence quantum yield is maintained, but its lifetime decreases
by about 30% due to the combination of faster radiative (in
relation with the hyperchromic effect) and nonradiative con-
stants. In comparison, the lengthening of the conjugated
rods based on phenylene–ethynylene oligomers leads to a
definite hyperchromic effect, but to only a slight bathochro-
mic shift of the absorption bands (Supporting Information,
Figure S4c). Similarly to phenylene–vinylene oligomers, a
red-shift of the emission bands is observed, whereas the
fluorescence quantum yields are maintained or decrease
only slightly.
Insertion of thienylene–vinylene, furylene–vinylene, or
fluorenylene–vinylene leads to bathochromic shifts of both
the absorption and emission bands (Supporting Information,
Figure S5). We note that the fluorenylene–vinylene leads to
the smallest red-shift and highest fluorescence quantum
yield, whereas the thienylene–vinylene unit leads to the larg-
est red-shift and lowest quantum yield, most probably be-
cause of increased nonradiative decay due to enlarged inter-
system crossing. Interestingly, the furylene–vinylene unit
leads to a significantly longer fluorescence lifetime, most
probably because of a reduction in the radiative decay due
to the marked red-shift of the absorption band, which is not
compensated by a hyperchromic effect of the absorption
band, as well as to higher Stokes shifts relative to other con-
jugating units.
Connector effect: phenylene–vinylene versus phenylene–ethy-
nylene: Changing the nature of the conjugated linker allows
spectral tuning of both the absorption and emission charac-
teristics. Replacing a triple bond by a double bond induces a
bathochromic shift and hyperchromic effect of both the ab-
sorption and emission bands, in agreement with an extended
electronic conjugation in the ground and excited states (Sup-
porting Information, Figure S2). Interestingly, the fluores-
cence lifetime always increases, most likely due to the
ꢁ
higher stretching frequency of a C C bond relative to that
of a C=C bond, which is responsible for more efficient non-
radiative decay.
On the other hand, replacement of a triple bond by a
double bond in elongated derivatives (PE2) produces very
different effects on the fluorescence quantum yield, depen-
A
shorter derivatives (i.e., connectors=PE and PV) show sim-
ilar fluorescence quantum yields. For the longer derivatives,
the replacement of a triple bond by a double bond does not
significantly affect the fluorescence quantum yield if the
substituted triple bond is positioned next to the central
block (i.e., connector=PE–PV instead of PE2). However, a
decrease of 25–40% in the fluorescence quantum yield is
obtained if the double bond is located close to the end-
groups (i.e., linker PV–PE instead of PE2).[103] This demon-
strates that subtle changes in the topology of the conjugated
rods may strongly influence the photoluminescence efficien-
cy of the series of quadrupolar fluorophores investigated in
the present work. Interestingly, further replacement of a
triple bond by a double bond (i.e., connector=PV2) restores
high fluorescence quantum yields.
Connector effect: influence of arylene moieties: Replacing a
phenyl unit by a thienyl unit in the conjugated connectors
always induces a significant bathochromic shift of the emis-
sion band, but leads either to a blue-shift (PV versus TV
and PV–TV versus TV2) or a red-shift (PV2 versus PV–TV
or TV2) of the absorption band (Supporting Information,
Figure S3), indicating that the reduction in the aromaticity
in the connectors does not necessarily lead to a reduction of
the electronic gap between the ground and excited states.
On the other hand, the introduction of the low-aromaticity
thiophene heterocycle in the conjugated systems always re-
sults in lower fluorescence quantum yields. In most cases,
larger Stokes shifts are observed, but no major nor regular
effects are visible on the fluorescence lifetime. This can be
related to the combination of slower radiative decays, relat-
ed to the red-shifted emission, and greater nonradiative
decay due to enlarged intersystem crossing.[104]
End-groups effect: Finally, we note that increasing either the
electron-withdrawing (Supporting Information, Figure S6a)
or electron-releasing (Supporting Information, Figure S6b)
character of the peripheral groups leads to a bathochromic
shift of both the absorption and emission bands, indicative
of a more pronounced either core-to-periphery or periph-
ery-to-core intramolecular charge transfer. This indicates
that the core can act as either an acceptor[105] or a donor
moiety,[106] depending on the peripheral counterparts. This
was confirmed by molecular orbital calculations.
We observe that pull–pull compounds appear blue-shifted,
compared to push–push derivatives. Interestingly, increasing
the donor strength leads to a slight decrease in the fluores-
cence quantum yield, whereas increasing the acceptor
strength leads to an increase.
Length effect: Increasing the connector length induces a sys-
tematic, but more or less pronounced, red-shift and hyper-
chromic effect on the absorption bands. On the other hand,
Chem. Eur. J. 2007, 13, 1481 – 1498
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1487

M. Blanchard-Desce, O. Mongin et al.
Two-photon absorption
resonant TPA reported recently[109–112]).The TPA cross sec-
tions were determined by comparing their TPEF to that of
fluorescein in water (pH 11),[107] according to the following
Equation (1):
The TPA spectra of the fluorophores were determined in
the NIR range (700–1000 nm) by investigating their two-
photon-excited fluorescence (TPEF) in 10ꢀ4 m toluene solu-
tions. The measurements were performed under excitation
with 150 fs pulses from a Ti:sapphire laser by using the ex-
perimental protocol of Xu and Webb.[107] The quadratic de-
pendence of the TPEF signal on the excitation intensity was
checked for each data point and confirmed that no photode-
gradation or saturation occurs. TPEF allows direct measure-
ment of the TPEF-action cross section s2F, the relevant
figure of merit for imaging applications. From these values,
the corresponding TPA cross sections s2 can be derived.
This method has been recognized to be more reliable than
nonlinear transmission measurements.[108] We emphasize
that experiments were conducted in the femtosecond
regime, thereby preventing contribution from linear nonre-
sonant absorption or from excited-state absorption that is
known to lead to artificially enhanced “effective” TPA cross
sections if measurements are conducted in the nanosecond
regime. We also stress that the reported values are non-one-
photon resonant values, meaning that these chromophores
could actually allow for the three-dimensional resolution of-
fered by selective two-photon excitation in the NIR region.
This is not the case if even slight one-photon absorption is
present (such as for a number of chromophores with giant
Ss hr Fr C
Sr hs Fs Cs
ð1Þ
ss ¼
r sr
in which the subscripts s and r refer to the sample and refer-
ence molecules, respectively. The intensity of signal collect-
ed by a photomultiplier was denoted as S. The h and F are
the overall fluorescence collection efficiency and the fluo-
rescence quantum yield, respectively. The number density of
the molecules in solution is denoted as C. The sr is the TPA
cross-section value of the reference (i.e., fluorescein). The
experimental data are collected in Table 2.
From Table 2, we observe that in most cases the lowest-
energy TPA band is observed at a lower wavelength than
twice that of the lowest-energy band in the one-photon-ab-
sorption spectrum. In fact, as these quadrupoles are nearly
centrosymmetric, the one-photon excited state has only little
TPA activity[41,89,90] and the two-photon-allowed excited
state lies at higher energy. After two-photon excitation, re-
laxation to the lowest-energy excited state leads to the
lowest-energy one-photon-allowed excited state, thus allow-
ing for radiative deactivation to take place. Note that given
the spectral window investigated here, the TPA maxima cor-
Table 2. Structure–TPA properties of quadrupolar compounds in toluene.
[a]
OPA
max
TPA
max1
TPA
max2
[c]
[d]
Compound
Egap
2l
l
l
s2
Ne
s2/Ne
[eV]
[nm]
[nm]
[nm]
[GM][b]
[GM]
TPA
TPA
Name
End-group
Linker
Core
at 705 nm
at l
at l
max2
max1
13a
16a
13b
14
16b
17a
17b
NHex2
NHex2
NHex2
NOct2
NHex2
NOct2
NHex2
PE
PV
PE2
PV–PE
PE–PV
PV–FV
PV–TV
BP
BP
BP
BP
BP
BP
BP
3.12
2.90
3.06
2.87
2.92
2.59
2.54
748
802
762
812
800
886
916
–
–
–
–
–
–
–
960
890
740
610
1140
1230
810
–
–
–
–
–
–
28
28
44
44
44
44
44
31.8
37.1
18.6
25.9
28.0
18.4
69.1
730
750
815
740
850
880
1040
820
910
1050
420
1350
–
3040
1020
19a
23
28
NHex2
OMe
NH2
NBu2
Pip
NHex2
NHex2
NOct2
NBu2
NOct2
Pip
PE
PV
PV
PV
TV
PE2
PV2
PV–PE
PV–FlV
PV–TV
TV2
Fl
Fl
Fl
Fl
Fl
Fl
Fl
Fl
Fl
Fl
Fl
3.07
3.12
3.01
2.85
2.88
3.03
2.73
2.84
2.76
2.50
2.53
774
762
784
830
774
774
862
822
858
940
902
–
–
–
740
–
735
730
815
730
880
735
–
–
–
–
–
–
815
–
–
1200
110
400
1130
95
1080
2110
1970
3470
5480
850
–
–
–
–
–
–
–
–
–
28
28
28
28
28
44
44
44
56
44
44
42.9
3.9
14.3
45.0
3.4
24.5
48.0
44.8
62.0
124.5
19.3
24
1260
–
34a
19b
30
20
32
1020
1920
1150
2960
1530
680
1210
–
–
–
–
31
34b
–
–
21b
21a
26a
21c
26b
SO2CF3
SO2Oct
SO2Me
SO2Oct
SO2Me
PE
PE
PV
PV–PE
PV2
Fl
Fl
Fl
Fl
Fl
3.20
3.30
3.07
3.10
2.87
744
726
774
764
824
730
730
–
–
725
–
–
–
–
83
52
220
610
1040
68
33
–
–
960
–
–
–
–
420
32
32
32
48
48
2.6
1.6
6.9
12.7
21.7
815
[a]The electronic gap (E gap) is calculated from the absorption and emission maxima. [b]1 GM =10ꢀ50 cm4 sphotonꢀ1; TPEF measurements were per-
formed by using a mode-locked Ti:sapphire laser delivering 80 fs pulses at 80 MHz, calibrating with fluorescein.[107] [c]Effective number of p electrons in
the conjugated system.[114] [d]Largest TPA cross section measured in the 700–1000 nm range, normalized by the effective number Ne of p electrons in
the conjugated system.
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Quadrupolar Fluorophores
FULL PAPER
responding to this higher-lying state is not systematically
reached for all chromophores (Table 2).
End-groups effect: As noted from Table 2 and illustrated in
Figure 2, push–push chromophores show larger TPA cross
Figure 4. TPA spectra of 21a and 21b in toluene: acceptor-strength
effect.
fluorene, always leads to a significant increase in the TPA
cross section (Table 2). For instance, as observed from
Figure 5, the push–push fluorene-core derivative 24 shows
larger TPA cross sections than its biphenyl analogue 16a in
the whole red-NIR region.
Figure 2. TPA spectra of 26b and 30 in toluene: end-group (push–push
vs. pull–pull) effect.
sections in the NIR region than corresponding pull–pull de-
rivatives, following the definite red-shift of both the one-
photon- and two-photon-absorption spectra and the reduc-
tion of the electronic gap between ground and excited
states. Increasing the strength of electron-donating end-
groups results in a pronounced enhancement of the TPA
cross sections in the NIR region, again following the red-
shift of both one- and two-photon-absorption spectra of
push–push derivatives, as illustrated in Figure 3 and ob-
served from Table 2. A similar effect is observed with elec-
tron-withdrawing groups (Figure 4).
Figure 5. TPA spectra of 16a and 24 in toluene: core effect.
Connector effect: phenylene–vinylene versus phenylene–ethy-
nylene: We observe from Table 2 that replacement of a
triple bond by a double bond always leads to a significant
increase in the TPA cross sections in the NIR region, what-
ever the nature of the end-groups (D or A) of the core
moiety and of the length of the conjugated rods. In addition,
the replacement of triple bonds by double bonds also indu-
ces a significant broadening and red-shift of the TPA spec-
tra, as illustrated in Figure 6. This effect parallels the red-
shift of both absorption and emission bands, that is, it corre-
lates with the reduction of the electronic gap between
ground and excited states. As a result, all fluorophores built
from vinylene linkers instead of ethynylene linkers show
much larger TPA cross sections in the whole red-NIR
region, the effect being more pronounced for higher wave-
lengths, as clearly seen from Figure 6. This is of particular
importance for imaging applications because 1) improved
penetration depth is achieved upon shifting to higher wave-
length (due to reduction of scattering losses) and 2) spectral
Figure 3. TPA spectra of 23, 28, and 24 in toluene: donor-strength effect.
Core effect: Comparison of push–push derivatives built from
the different core moieties and bearing similar end-groups
demonstrates that the nature of the conjugated core signifi-
cantly influences the TPA spectra and governs the TPA
cross-section magnitude. Independently of the connector
nature, rigidification of the biphenyl unit, as obtained with
Chem. Eur. J. 2007, 13, 1481 – 1498
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1489

M. Blanchard-Desce, O. Mongin et al.
Figure 6. TPA spectra in toluene of 19b, 20, and 30: linker effect.
broadening offers much more flexibility in terms of two-
photon excitation (allowing for a wider choice of laser sour-
ces).
Connector effect: influence of arylene moieties: The nature
of the arylene unit in the conjugated rods also plays an im-
portant role in tuning the TPA spectra and influencing the
TPA cross-section magnitude. For derivatives of comparable
length and bearing similar peripheral groups, we observe
that replacement of the phenyl unit by a thienyl unit in the
conjugated backbone has a markedly different impact, de-
pending on its position in the conjugated backbone. In par-
ticular, if a terminal phenyl ring is substituted by a thienyl
ring, a major decrease in the TPA efficiency is obtained
(Table 2). For instance, compound 34a displays TPA cross
sections of about one order of magnitude lower than com-
pound 24 (Figure 7a) throughout the red-NIR range. A simi-
lar effect is observed if compounds 34b and 31 are com-
pared (Figure 7b). In contrast, if the phenyl ring is replaced
by a thienyl ring close to the core, a distinct increase in the
TPA magnitude, as well as a red-shift and definite broaden-
ing of the TPA spectrum in the NIR region, is observed
(Table 2). For instance, compound 31 displays a TPA cross
section that is more than twice that of compound 30 at
705 nm and more than three times that at 900 nm. As a
result, fluorophore 31 maintains a large TPEF-action cross
section (s2F) at 1 mm (i.e., 265 GM), a region of particular
interest for imaging applications due to the increased pene-
tration depth in tissues and availability of lower-cost lasers.
This effect parallels the bathochromic shift of both the ab-
sorption and emission bands, that is, the significant reduc-
tion in the electronic gap.
Figure 7. TPA spectra in toluene of a) 24 and 34a; b) 30, 31, and 34b; c)
17a and 17b: connector effects.
by a furyl ring, whose aromaticity is much lower,[113] in the
conjugated system results in a major decrease in the TPA
cross sections within the whole red-NIR spectral range (Fig-
ure 7c). This clearly demonstrates the limitations of the pop-
ular strategy consisting of reducing the aromaticity of conju-
gated systems for improvement of nonlinear, and particular-
ly TPA, properties. Clearly, a more subtle approach is
needed for molecular optimization of TPA properties.
We emphasize that the present study demonstrates that
the topology of the conjugated connectors dramatically influ-
ences the TPA properties. Indeed, replacing the phenyl ring
by the less aromatic thienyl ring may have either a positive
or negative effect on TPA properties, depending on its loca-
tion in the conjugated system. Furthermore, decreasing the
aromaticity of the connector does not necessarily lead to en-
hanced TPA properties, even if the aromatic connector is lo-
cated close to the core. This is clearly shown from compari-
son of compounds 17a and 17b: replacing the thienyl ring
Topology effect: The importance of the topology of the con-
jugated system is also seen clearly from comparison of com-
pounds 14 and 16b that have the same end-groups, core,
and analogous connectors, except for the location of the
triple-bond linker either close to the core (molecule 14) or
close to the end-groups (molecule 16b). Although com-
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Quadrupolar Fluorophores
FULL PAPER
pounds 14 and 16b have similar one-photon characteristics
(Table 1), they clearly show different TPA spectra within the
NIR range (Figure 8). Indeed, if the triple bond linker is lo-
cated closer to the core, the low-energy TPA band is red-
Figure 8. TPA spectra of 16b and 14 in toluene: topology effect.
shifted, its maximum being shifted by 75 nm. Consequently,
compound 14 shows higher TPA efficiency at wavelengths
longer than 770 nm. As an illustration, the TPA cross section
of molecule 14 is more than twice that of its analogue 16b
at 850 nm. Hence, compound 14, although showing similar
linear transparency to compound 16b, has broader TPA in
the NIR. Such an effect is of particular interest in optical-
limiting applications for which improved nonlinearity/trans-
parency trade-off is an important issue. In this respect, it is
also interesting to note that chromophore 14 has a lower
fluorescence quantum yield while maintaining a similar ex-
cited-state lifetime, thus offering better characteristics for
broadband optical limiting in the visible-NIR region based
on multiphoton absorption (including two-photon-induced
excited-state absorption in the nanosecond regime).[35] This
shows that subtle changes in the structures of the conjugated
arms may have important implications in terms of molecular
engineering for specific applications.
Figure 9. TPA spectra in toluene of a) 24 and 30; b) 34a and 34b; and c)
13a and 13b: length effects.
Length effect: The lengthening of the conjugated rods based
on either phenylene–vinylene (Figure 9a) and thienylene–vi-
nylene (Figure 9b) oligomers leads to a major increase in
the TPA magnitude throughout the whole red-NIR range,
which parallels the lowering of the electronic gap between
the ground and the first excited states (Table 2). It should
be stressed that the TPA magnitude increases by more than
the size of the molecule in the case of oligomeric phenyl-
ene–vinylene or thienylene–vinylene connectors, as indicat-
ed by s2/Ne, the peak TPA cross section normalized by the
effective number of electrons[114] (Table 2). In addition, we
observe a marked red-shift of the TPA bands that results in
a significant improvement in the TPA properties at higher
wavelength. As a result, elongated fluorophores show not
only higher TPA peaks, but also much broader TPA activity
in the target spectral range. This superlinear increase indi-
cates that the lengthening approach is a valid strategy for
TPA enhancement in the red-NIR range.
However, it should be stressed that the amplitude of the
increase depends markedly on the nature of the extensor.
For instance, the lengthening of the conjugated rods based
on phenylene–ethynylene oligomers does not necessarily
lead to an increase in the TPA response (Table 2 and Fig-
ure 9c): a marked red-shift and broadening of the TPA re-
sponse is obtained in the red-NIR range (Figure 9c), where-
as the one-photon-absorption band is only slightly red-shift-
ed (Supporting Information, Figure S4c). Consequently, a
major increase in TPA efficiency in the NIR region is ob-
served (by a factor of three to more than ten in the 750–
850 nm region) with nearly no loss of linear transparency.
Chem. Eur. J. 2007, 13, 1481 – 1498
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1491

M. Blanchard-Desce, O. Mongin et al.
Hence, phenylene–ethynylene oligomers appear as suitable
connectors for broadband optical limiting in the visible-NIR
region.
Finally, incorporation of a fluorenylene–vinylene or a
thienylene–vinylene extensor in the conjugated arms also
leads to a major increase in the TPA efficiency throughout
the whole red-NIR range, that is, the spectral range of inter-
est (Figure 10). Interestingly, the strongest effect (both net
structure–property relationships of great significance for
both spectral tuning and amplification of the molecular TPA
in the NIR spectral range. The influence of each moiety
constituting these quadrupolar structures (cores, linkers,
connectors, and end-groups) was studied in detail. Push–
push systems were found to be more efficient than pull–pull
systems, and planarization of the core (fluorene vs. biphen-
yl) always leads to an increase in the TPA cross sections.
The role of the conjugated rods should also be emphasized:
their length is, of course, an important parameter, however,
the nature of the linkers (double or triple bonds) and of the
arylene units (phenylene, thienylene, furylene, fluorenylene)
is also of particular importance. Concerning this last point,
we have shown that the classical strategy consisting of re-
ducing the aromaticity of the connectors does not necessari-
ly give rise to an enhancement of the TPA response within
the spectral region of interest. Moreover, we have demon-
strated that the topology of the conjugated system, that is,
the location of linkers and connectors in the conjugated
rods, can dramatically influence the TPA properties. Small
changes in the structure may have important implications in
terms of molecular engineering for specific applications, be-
cause the TPA properties (in terms of cross sections, posi-
tion of the maximum, and bandwidth), as well as the one-
photon and the photoluminescence characteristics can be af-
fected considerably. Thus, it becomes possible to optimize
the transparency/TPA efficiency and the fluorescence/TPA
efficiency trade-offs. With these findings, quadrupolar fluo-
rophores combining very large peak TPA cross sections (up
to 5480 GM), broad TPA bands throughout the whole 700–
1000 nm range, and high fluorescence quantum yields (rang-
ing from 0.45 to 0.98) could, thus, be obtained. Such com-
pounds are of particular interest for TPEF microscopy,[45] as
well as optical limiting in the visible[39] and NIR[35] regions.
Figure 10. TPA spectra of 24, 30, 32, and 31 in toluene.
increase and spectral broadening further to the NIR region)
is obtained for the thienylene–vinylene connector, in corre-
lation with the smallest energy gap between relaxed ground
and excited states. Compared to insertion of a phenylene–vi-
nylene, the insertion of a fluorenylene–vinylene allows for a
major TPA increase, mainly to the blue of the lowest-energy
TPA peak. In contrast, insertion of a thienylene–vinylene
unit allows a larger TPA increase throughout the whole red-
NIR range than insertion of a phenylene–vinylene unit
(Figure 10). In comparison to both thienylene–vinylene
oligomers and phenylene–vinylene oligomers, extended
arms based upon the alternation of thienylene–vinylene and
phenylene–vinylene moieties lead to major TPA enhance-
ment and broadening in the red-NIR range. Indeed, chro-
mophore 31 shows a normalized TPA cross section (s2/Ne)
measured in the femtosecond regime similar to that of the
best (in terms of non-one-photon resonant TPA) chromo-
phore reported so far,[115] although being blue-shifted by
nearly 40 nm. Thus, this molecule is particularly promising
for optical limiting in the 700–900 nm region in the nanosec-
ond regime. The present study provides evidence that by
playing not only on the length of the conjugated arms, but
more importantly on their nature and their topology, major
(and nonlinear) increases in the TPA efficiency throughout
the whole NIR range can be achieved.
Experimental Section
Photophysical methods: UV/Vis spectra were recorded by using a Jasco
V-570 spectrophotometer. Steady-state fluorescence measurements were
performed at RT on dilute solutions (ca. 10ꢀ6 m) by using an Edinburgh
Instruments (FLS 920) spectrometer working in photon-counting mode,
equipped with a calibrated quantum counter for excitation correction.
Fully corrected emission spectra were obtained, for each compound, at
lex =lambasx with Al ꢂ0.1 to minimize internal absorption. Fluorescence
ex
quantum yields were measured by using standard methods[116] on air-equi-
librated samples at RT. Fluorescein in 0.1m NaOH (F=0.90 at lex
=
470 nm) was used as a reference.[117] The reported fluorescence quantum
yields are within ꢃ10%. Fluorescence lifetimes were measured by time-
correlated single-photon counting (TCSPC) by using the same FLS 920
fluorimeter. Excitation was achieved by a hydrogen-filled nanosecond
flashlamp (repetition rate 40 kHz). The instrument response (FWHM ca.
1 ns) was determined by measuring the light scattered by a Ludox sus-
pension. The TCSPC traces were analyzed by standard iterative reconvo-
lution methods implemented in the software of the fluorimeter. All com-
pounds displayed strictly monoexponential fluorescence decays (c2 <1.1).
Two-photon-absorption (TPA) measurements were conducted by investi-
gating the two-photon-excited fluorescence (TPEF) of the fluorophores
in toluene at RT on air-equilibrated solutions (10ꢀ4 m), by using a Ti:sap-
phire laser delivering 150-fs excitation pulses, according to the experi-
mental protocol established by Xu and Webb.[107] This protocol avoids
Conclusion
This systematic study of the absorption, photoluminescence,
and two-photon-absorption properties on such a broad
series of quadrupolar fluorophores allowed us to derive
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Chem. Eur. J. 2007, 13, 1481 – 1498

Quadrupolar Fluorophores
FULL PAPER
contributions from excited-state absorption that are known to result in
largely overestimated TPA cross sections. The quadratic dependence of
the fluorescence intensity on the excitation intensity was verified for
each data point, indicating that the measurements were carried out in in-
tensity regimes in which saturation or photodegradation do not occur.
TPEF measurements were calibrated relative to the absolute TPEF-
(86%) of 13b: M.p. 234–2358C; 1H NMR (300.13 MHz, CDCl3): d=7.61
(s, 8H), 7.49 and 7.46 (AA’XX’,
JAX =8.7 Hz, 8H), 7.36 and 6.56
(AA’XX’, JAX =9.3 Hz, 8H), 3.27 (m, 8H), 1.66–1.52 (m, 8H), 1.31 (m,
24H), 0.90 ppm (t, J=6.6 Hz, 12H); 13C NMR (50.32 MHz, CDCl3): d=
148.1, 140.0, 132.9, 132.1, 131.4, 131.1, 126.9, 124.3, 122.5, 121.8, 111.1,
108.3, 93.2, 90.6, 90.4, 87.0, 50.9, 31.7, 27.2, 26.8, 22.7, 14.0 ppm; MS (ES+
, CH2Cl2/MeOH): m/z: 921.6 [M+H]+, 461.4 [M+2H]2+; HRMS (ES+,
CH2Cl2/MeOH): m/z: calcd for C68H77N2 [M+H]+: 921.6087; found:
921.6110; elemental analysis calcd (%) for C68H76N2 (921.36): C 88.65, H
8.31, N 3.04; found: C 88.72, H 8.41, N 2.80.
action cross sections determined by Xu and Webb for fluorescein (10ꢀ4
m
in 0.01m aqueous NaOH) in the 690–1000 nm range.[107,118] This procedure
provides the TPEF-action cross section s2F from which the correspond-
ing s2 value is derived. The experimental uncertainty of the absolute
action cross sections determined by this method has been estimated to be
ꢃ20%.[107]
4,4’-[(1,1’-Biphenyl)-4,4’-diylbis[2,1-ethynediyl-4,1-phenylene-(1E)-2,1-
ethenediyl]]bis(N,N-dioctylbenzenamine) (14): Reaction of 12 (34.6 mg,
0.171 mmol) with 4a (215 mg, 0.394 mmol), as described for 13a, for
3.5 h, with subsequent purification by column chromatography (heptane/
CH2Cl2, gradient from 40:60 to 0:100) and crystallization, afforded
144.4 mg (81%) of 14: M.p. 221–2228C; 1H NMR (200.13 MHz, CDCl3):
d=7.61 (s, 8H), 7.51 and 7.44 (AA’XX’, JAX =8.8 Hz, 8H), 7.38 and 6.62
Synthetic procedures
General methods: All air- or water-sensitive reactions were carried out
under argon. Solvents were generally dried and distilled prior to use. Re-
actions were monitored by performing thin-layer chromatography on
Merck silica gel or neutral aluminum oxide 60 F254 precoated aluminum
sheets. Column chromatography: Merck silica gel Si 60 (40–63 mm, 230–
400 mesh), except otherwise noted. Melting points were determined by
using an Electrothermal IA9300 digital melting-point instrument. NMR:
Bruker AM 200 (1H: 200.13 MHz), AM250 (1H: 250.13 MHz, 13C:
62.90 MHz, 31P: 101.25 MHz), ARX 200 (1H: 200.13 MHz, 13C:
50.32 MHz), or Avance AV 300 (1H: 300.13 MHz, 13C: 75.48 MHz, 19F:
(AA’XX’,
JAX =8.8 Hz, 8H), 7.08 (d, J=16.3 Hz, 2H), 6.86 (d, J=
16.3 Hz, 2H) 3.28 (m, 8H), 1.67–1.52 (m, 8H), 1.31 (m, 40H), 0.89 ppm
(t, J=6.3 Hz, 12H); 13C NMR (50.32 MHz, CDCl3): d=148.0, 139.8,
138.5, 132.0, 131.8, 129.9, 128.8, 127.9, 126.8, 125.8, 124.1, 122.7, 120.8,
111.6, 90.9, 89.7, 51.1, 31.8, 29.5, 29.3, 27.3, 27.2, 22.6, 14.1 ppm; HRMS
(LSIMS+, mNBA): m/z: calcd for C76H96N2 [M+]: 1036.7574; found:
1036.7565; elemental analysis calcd (%) for C76H96N2 (1037.61): C 87.97,
H 9.33, N 2.70; found: C 87.95, H 9.56, N 2.71.
1
282.38 MHz, 31P: 121.50 MHz), in CDCl3 solutions; H chemical shifts (d)
are given in ppm relative to TMS as internal standard, 13C chemical shifts
are given relative to the central peak of CDCl3 at 77.0 ppm, 31P relative
to H3PO4 as external standard, and 19F relative to CFCl3 as internal stan-
dard. High- and low-resolution mass spectra measurements were per-
formed at the Centre RØgional de Mesures Physiques de lꢁOuest
(C.R.M.P.O., Rennes) by using a Micromass MS/MS ZABSpec TOF in-
strument with EBE TOF geometry; liquid secondary ion mass spectrom-
etry (LSIMS) at 8 kV with Cs+ in m-nitrobenzyl alcohol (mNBA) or o-
nitrophenyloctyl ether (oNPOE); ES+ (electrospray ionization, positive
mode) at 4 kV; EI (electron ionization) at 70 eV; CI (chemical ioniza-
tion) with NH3 or CH4 as ionization gas. Elemental analyses were per-
formed at I.C.S.N.–C.N.R.S. (Gif-sur-Yvette, France) or at the
C.R.M.P.O. Compounds 1b,[92] 1e,[93] 3a–c,[94] 5a,[95] 5b,[96] 7a,[97] 9a,[98]
12,[100] and 15a[101] were synthesized according to the respective literature
procedures. [(4-Methoxyphenyl)methyl]triphenylphosphonium bromide
was prepared according to ref. [119]. {[5-(1-Piperidinyl)-2-thienyl]-
4,4’-[(1,1’-Biphenyl)-4,4’-diyldi-(1E)-2,1-ethenediyl]bis(N,N-dihexylben-
zenamine) (16a): NaH (0.45 g, 60% dispersion in mineral oil) was added
to a solution of 15b (1.70 g, 3.74 mmol) and 1e[93] (2.494 g, 7.48 mmol) in
anhyd THF (70 mL). The mixture was stirred at 208C for 20 h, then
under reflux for 4 h. After addition of water (25 mL), the THF was
evaporated. The resulting precipitate was filtered and washed successive-
ly with EtOH and pentane. The crude product was then purified by
column chromatography (heptane/CH2Cl2 60:40) to yield 1.90 g (70%) of
16a: M.p. 147–1488C; 1H NMR (200.13 MHz, CDCl3): d=7.59 and 7.53
(AA’XX’, JAX =8.6 Hz, 8H), 7.39 and 6.62 (AA’XX’, JAX =8.8 Hz, 8H),
7.08 (d, J=16.2 Hz, 2H), 6.90 (d, J=16.2 Hz, 2H), 3.28 (m, 8H), 1.59 (m,
8H), 1.32 (m, 24H), 0.91 ppm (t, J=6.4 Hz, 12H); 13C NMR (50.32 MHz,
CDCl3): d=147.8, 138.7, 137.2, 128.8, 127.8, 126.8, 126.3, 124.4, 123.1,
111.6, 51.0, 31.7, 27.3, 26.8, 22.7, 14.1 ppm; HRMS (LSIMS+, mNBA):
m/z: calcd for C52H72N2 [M+]: 724.5696; found: 724.5694; elemental anal-
ysis calcd (%) for C52H72N2 (725.15): C 86.13, H 10.01, N 3.86; found: C
85.81, H 10.03, N 3.78.
methyl}triphenylphosphonium iodide was prepared analogously to
ref. [94]. Phosphonates 9b and 11 were prepared analogously to ref. [98]
and ref. [120], respectively. 9,9-Dinonyl-9 H-fluorene (18a) was prepared
by reaction of fluorene with 1-bromononane using n-butyllithium in
THF, analogously to ref. [121]. Synthetic procedures and characterization
data for all quadrupolar chromophores are given hereafter, and those for
intermediate compounds can be found in the Supporting Information.
4,4’-[(1,1’-Biphenyl)-4,4’-diylbis
ethynediyl]]bis(N,N-dihexylbenzenamine) (16b): NaH (26 mg, 60% dis-
persion in mineral oil) was added to solution of 15b (75.4 mg,
A
a
0.166 mmol), 2b (148.5 mg, 0.381 mmol), and [18]crown-6 (4.3 mg) in
anhyd THF (8 mL). The mixture was stirred at 408C for 3 h. After addi-
tion of water, the precipitate was filtered and washed with water, EtOH,
Et2O, and pentane successively, and dried under vacuum. The product
was then purified by column chromatography (heptane/CH2Cl2, gradient
from 40:60 to 0:100) to yield 128 mg (84%) of 16b: M.p. 243–2448C;
1H NMR (200.13 MHz, CDCl3): d=7.65 and 7.59 (AA’XX’, JAX =8.7 Hz,
8H), 7.49 (s, 8H), 7.37 and 6.57 (AA’XX’, JAX =9.1 Hz, 8H), 7.15 (s,
4H), 3.28 (m, 8H), 1.65–1.50 (m, 8H), 1.32 (m, 24H), 0.91 ppm (t, J=
6.6 Hz, 12H); MS (ES+, CHCl3/MeOH): m/z: 925.6 [M+H]+, 463.4
4,4’-[(1,1’-Biphenyl)-4,4’-diyldi-2,1-ethynediyl]bis(N,N-dihexylbenzenam-
T
0.445 mmol) and 1b[92] (431 mg, 1.112 mmol) in 4 mL of toluene/Et3N
(5:1) by blowing argon for 20 min. Then CuI (3.4 mg, 0.018 mmol) and
[Pd(PPh3)2Cl2](12.5 mg, 0.018 mmol) were added, and deaeration was
T
continued for 10 min. Thereafter, the mixture was stirred at 208C for 2 h.
The solvent was removed under reduced pressure, and the crude product
was purified by column chromatography (heptane/CH2Cl2 90:10 then
80:20) to yield 270.4 mg (84%) of 13a: M.p. 113.5–114.58C; 1H NMR
[M+2H]2+
;
HRMS (ES+, CHCl3/MeOH): m/z: calcd for C68H81N2
(200.13 MHz, CDCl3): d=7.56 (s, 8H), 7.38 and 6.58 (AA’XX’, JAX
=
[M+H]+: 925.6400; found: 925.6391; elemental analysis calcd (%) for
C68H80N2 (925.39): C 88.26, H 8.71, N 3.03; found: C 88.03, H 8.95, N
2.97.
9.0 Hz, 8H), 3.28 (m, 8H), 1.66–1.52 (m, 8H), 1.32 (m, 24H), 0.91 ppm
(t, J=6.5 Hz, 12H); 13C NMR (50.32 MHz, CDCl3): d=147.9, 139.2,
132.9, 131.6, 126.6, 123.4, 111.2, 108.6, 91.9, 87.0, 50.9, 31.7, 27.2, 26.8,
22.7, 14.0 ppm; HRMS (LSIMS+, mNBA): m/z: calcd for C52H68N2 [M+]:
720.5383; found: 720.5390; elemental analysis calcd (%) for C52H68N2
(721.12): C 86.61, H 9.50, N 3.88; found: C 86.42, H 9.64, N 3.90.
4,4’-[(1,1’-Biphenyl)-4,4’-diylbis[(1E)-2,1-ethenediyl-5,2-furanediyl-(1E)-
C
2,1-ethenediyl]]bis(N,N-dioctylbenzenamine) (17a): NaH (150 mg, 60%
dispersion in mineral oil) was added to a solution of 15b (216 mg,
0.475 mmol) and 6a (422 mg, 0.965 mmol) in anhyd THF (10 mL). The
mixture was stirred at 208C for 19 h. After addition of water, the precipi-
tate was filtered and washed with water, EtOH, and pentane successively,
and dried under vacuum, to yield 390 mg (80%) of 17a: M.p. 247–2498C;
1H NMR (200.13 MHz, CDCl3): d=7.63 and 7.56 (AA’XX’, JAX =8.3 Hz,
8H), 7.37 and 6.62 (AA’XX’, JAX =8.6 Hz, 8H), 7.13 (d, J=16.3 Hz, 2H),
4,4’-[(1,1’-Biphenyl)-4,4’-diylbis(2,1-ethynediyl-4,1-phenylene-2,1-ethyne-
diyl)]bis(N,N-dihexylbenzenamine) (13b): Reaction of 12 (26.1 mg,
0.129 mmol) with 2a (146 mg, 0.299 mmol), as described for 13a, with
subsequent purification by column chromatography (heptane/CH2Cl2,
gradient from 50:50 to 0:100) and crystallization, afforded 102.6 mg
Chem. Eur. J. 2007, 13, 1481 – 1498
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
1493

M. Blanchard-Desce, O. Mongin et al.
7.08 (d, J=15.8 Hz, 2H), 6.91 (d, J=16.3 Hz, 2H), 6.67 (d, J=15.8 Hz,
2H), 6.39 (d, J=3.3 Hz, 2H), 6.28 (d, J=3.3 Hz, 2H), 3.29 (m, 8H), 1.56
(m, 8H), 1.31 (m, 40H), 0.89 ppm (t, J=6.6 Hz, 12H); 13C NMR
(50.32 MHz, CDCl3): d=154.3, 152.1, 147.8, 139.4, 136.4, 131.3, 129.4,
128.0, 127.7, 127.0, 126.7, 125.7, 124.1, 116.3, 111.6, 109.2, 51.0, 31.8, 29.5,
29.3, 27.3, 27.2, 22.7, 14.1 ppm; HRMS (LSIMS+, mNBA): m/z: calcd for
C72H96N2O2 [M+]: 1020.7472; found: 1020.7477.
column chromatography (heptane/CH2Cl2 35:65), afforded 186.0 mg
(84%) of 21a; 1H NMR (200.13 MHz, CDCl3): d=7.91 and 7.73
(AA’XX’, JAX =8.6 Hz, 8H), 7.72 (d, J=8.0 Hz, 2H), 7.56 (d, J=8.0 Hz,
2H), 7.54 (s, 2H), 3.11 (m, 4H), 2.00 (m, 4H), 1.73 (m, 4H), 1.41–1.02
(m, 44H), 0.87 (t, J=6.5 Hz, 6H), 0.81 (t, J=6.6 Hz, 6H), 0.61 ppm (m,
4H); 13C NMR (50.32 MHz, CDCl3): d=151.2, 141.2, 138.1, 132.0, 131.0,
129.1, 128.1, 126.1, 121.1, 120.2, 94.3, 88.2, 56.3, 55.3, 40.2, 31.7, 31.6, 29.9,
29.4, 29.2, 29.1, 28.9, 28.8, 28.2, 23.7, 22.59, 22.55, 22.50, 14.02, 14.01 ppm;
HRMS (LSIMS+, mNBA): m/z: calcd for C63H86O4S2 [M+]: 970.5968;
found: 970.5981; elemental analysis calcd (%) for C63H86O4S2 (971.49): C
77.89, H 8.92; found: C 77.66, H 8.96.
4,4’-[(1,1’-Biphenyl)-4,4’-diylbis[(1E)-2,1-ethenediyl-5,2-thiophenediyl-
G
(1E)-2,1-ethenediyl]]bis(N,N-dihexylbenzenamine) (17b): Reaction of
15b (227 mg, 0.5 mmol) with 6c (415 mg, 1.04 mmol), as described for
17a, for 16 h, afforded 301 mg (64%) of 17b: M.p. 250–2528C; 1H NMR
(200.13 MHz, CDCl3): d=7.62 and 7.53 (AA’XX’, JAX =8.3 Hz, 8H), 7.33
and 6.61 (AA’XX’, JAX =8.7 Hz, 8H), 7.23 (d, J=16.6 Hz, 2H), 6.97 (d,
J=16.0 Hz, 2H), 6.94 (d, J=3.7 Hz, 2H), 6.89 (d, J=16.6 Hz, 2H), 6.86
(d, J=3.7 Hz, 2H), 6.84 (d, J=16.0 Hz, 2H), 3.28 (m, 8H), 1.57 (m, 8H),
1.32 (m, 24H), 0.91 ppm (t, J=6.2 Hz, 12H); HRMS (LSIMS+, mNBA):
m/z: calcd for C64H80N2S2 [M+]: 940.5763; found: 940.5758.
9,9-Dinonyl-2,7-bis{[4-[(trifluoromethyl)sulfonyl]phenyl]ethynyl}-9H-flu-
orene (21b): Reaction of 18b (175.7 mg, 0.26 mmol) with 8d (153.4 mg,
0.66 mmol), as described for 13a, at 408C for 14 h, with subsequent pu-
rification by column chromatography (heptane/CH2Cl2 80:20), afforded
138.0 mg (60%) of 21b; 1H NMR (200.13 MHz, CDCl3): d=8.04 and
7.82 (AA’XX’, JAX =8.5 Hz, 8H), 7.74 (d, J=7.9 Hz, 2H), 7.58 (d, J=
7.9 Hz, 2H), 7.56 (s, 2H), 2.02 (m, 4H), 1.26–1.07 (m, 24H), 0.81 (t, J=
6.6 Hz, 6H), 0.62 ppm (m, 4H); 13C NMR (75.48 MHz, CDCl3): d=151.4,
141.6, 132.5, 132.4, 131.3, 130.7, 129.9, 126.4, 120.9, 120.4, 120.2 (q, J=
325.9 Hz), 96.7, 87.8, 55.5, 40.2, 31.8, 29.9, 29.5, 29.2, 23.7, 22.6, 14.0 ppm;
19F NMR (282.38 MHz, CDCl3): d=ꢀ78.22 ppm; HRMS (LSIMS+,
mNBA): m/z: calcd for C49H52F6O4S2 [M+]: 882.3211; found: 882.3225.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)di-2,1-ethynediyl]bis(N,N-dihex-
ylbenzenamine) (19a): Reaction of 18d (231.6 mg, 0.496 mmol) with
1b[92] (462.9 mg, 1.195 mmol), as described for 13a, for 3 h, with subse-
quent purification by column chromatography (heptane/CH2Cl2 90:10),
afforded 221 mg (45%) of 19a; 1H NMR (200.13 MHz, CDCl3): d=7.60
(d, J=8.3 Hz, 2H), 7.46 (d, J=8.3 Hz, 2H), 7.45 (s, 2H), 7.39 and 6.57
(AA’XX’, JAX =9.0 Hz, 8H), 3.27 (m, 8H), 1.96 (m, 4H), 1.58 (m, 8H),
1.32 (m, 24H), 1.30–0.99 (m, 24H), 0.90 (t, J=6.6 Hz, 12H), 0.83 (t, J=
6.7 Hz, 6H), 0.61 ppm (m, 4H); 13C NMR (50.32 MHz, CDCl3): d=150.9,
147.8, 140.0, 132.8, 130.3, 125.5, 122.7, 119.6, 111.2, 108.7, 91.1, 88.2, 55.1,
50.9, 40.5, 31.8, 31.7, 30.1, 29.6, 29.3, 29.2, 27.2, 26.8, 23.7, 22.7, 22.6, 14.1,
14.0 ppm; HRMS (LSIMS+, mNBA): m/z: calcd for C71H104N2 [M+]:
984.8200; found: 984.8209; elemental analysis calcd (%) for C71H104N2
(985.62): C 86.52, H 10.64, N 2.84; found: C 86.12, H 10.85, N 2.88.
9,9-Dinonyl-2,7-bis{[4-
A
AHCTREUNG
with 10 (271 mg, 0.562 mmol), as described for 13a, at 358C for 14 h,
with subsequent purification by column chromatography (heptane/
CH2Cl2 25:75 then 20:80), afforded 239.8 mg (87%) of 21c: M.p. 164–
1
1658C; H NMR (200.13 MHz, CDCl3): d=7.89 and 7.68 (AA’XX’, JAX
=
8.6 Hz, 8H), 7.69 (d, J=8.0 Hz, 2H), 7.53 (d, J=8.0 Hz, 2H), 7.60 and
7.54 (AA’XX’, JAX =8.8 Hz, 8H), 7.54 (s, 2H), 7.27 (d, J=16.5 Hz, 2H),
7.16 (d, J=16.5 Hz, 2H), 3.10 (m, 4H), 2.01 (m, 4H), 1.73 (m, 4H), 1.41–
1.00 (m, 44H), 0.86 (t, J=6.4 Hz, 6H), 0.83 (t, J=6.7 Hz, 6H), 0.62 ppm
(m, 4H); 13C NMR (50.32 MHz, CDCl3): d=151.1, 142.3, 140.7, 137.6,
136.1, 131.9, 131.7, 130.8, 128.5, 127.3, 127.0, 126.8, 125.9, 123.3, 121.8,
120.0, 92.0, 89.8, 56.3, 55.2, 40.3, 31.7, 31.6, 29.9, 29.4, 29.2, 29.1, 28.9,
28.8, 28.2, 23.7, 22.6, 22.54, 22.48, 14.01, 13.98 ppm; HRMS (LSIMS+,
mNBA): m/z: calcd for C79H98O4S2 [M+]: 1174.6907; found: 1174.6913; el-
emental analysis calcd (%) for C79H98O4S2 (1175.76): C 80.70, H 8.40;
found: C 80.71, H 8.41.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)bis(2,1-ethynediyl-4,1-phenylene-
2,1-ethynediyl)]bis(N,N-dihexylbenzenamine) (19b): Reaction of 18d
(100 mg, 0.214 mmol) with 2a (241 mg, 0.494 mmol), as described for
13a, for 20 h, with subsequent purification by column chromatography
(heptane/CH2Cl2, gradient from 90:10 to 80:20), afforded 208.6 mg
(82%) of 19b; 1H NMR (200.13 MHz, CDCl3): d=7.67 (d, J=8.4 Hz,
2H), 7.52 (d, J=8.4 Hz, 2H), 7.52 and 7.47 (AA’XX’, JAX =8.8 Hz, 8H),
7.50 (s, 2H), 7.37 and 6.57 (AA’XX’, JAX =8.9 Hz, 8H), 3.28 (m, 8H),
1.98 (m, 4H), 1.58 (m, 8H), 1.32 (m, 24H), 1.30–1.02 (m, 24H), 0.91 (t,
J=6.5 Hz, 12H), 0.82 (t, J=6.6 Hz, 6H), 0.61 ppm (m, 4H); 13C NMR
(50.32 MHz, CDCl3): d=151.1, 148.0, 140.7, 132.9, 131.4, 131.1, 130.7,
125.9, 124.2, 122.0, 121.9, 120.0, 111.1, 108.4, 93.1, 91.9, 89.8, 87.0, 55.2,
50.9, 40.3, 31.8, 31.7, 30.0, 29.5, 29.3, 29.2, 27.2, 26.8, 23.7, 22.7, 22.6,
14.04, 14.02 ppm; HRMS (LSIMS+, oNPOE): m/z: calcd for C87H112N2
[M+]: 1184.8826; found: 1184.8813; elemental analysis calcd (%) for
C87H112N2 (1185.86): C 88.12, H 9.52, N 2.36; found: C 88.00, H 9.65, N
2.18.
2,7-Bis[(1E)-2-(4-methoxyphenyl)ethenyl]-9,9-dinonyl-9H-fluorene (23):
E
tBuOK (87 mg, 0.77 mmol) was added to a solution of 22b (122.0 mg,
0.26 mmol) and 4-(methoxybenzyl)triphenylphosphonium bromide[119]
(261.8 mg, 0.57 mmol) in anhyd CH2Cl2 (5 mL). The mixture was stirred
at 208C for 48 h. After addition of water, extraction with CH2Cl2, and
drying (Na2SO4), the solvent was evaporated. The residue was purified
by filtration through a short pad of silica gel (CH2Cl2), to afford a mix-
ture of isomers, which was dissolved in Et2O (5 mL). A catalytic amount
of I2 was then added and the solution was stirred at 208C for 3 h under
light exposure (75-W lamp). The organic layer was washed with aq
Na2S2O3 and dried (Na2SO4). After evaporation of the solvent, the crude
product was purified by column chromatography (heptane/AcOEt 98:2
then 95:5) to yield 130.7 mg (75%) of 23; 1H NMR (200.13 MHz,
CDCl3): d=7.65 (d, J=7.8 Hz, 2H), 7.51 and 6.93 (AA’XX’, JAX =8.8 Hz,
8H), 7.48 (d, J=7.8 Hz, 2H), 7.46 (s, 2H), 7.16 (d, J=16.4 Hz, 2H), 7.07
(d, J=16.4 Hz, 2H), 3.85 (s, 6H), 2.02 (m, 4H), 1.27–1.08 (m, 24H), 0.82
(t, J=6.6 Hz, 6H), 0.69 ppm (m, 4H); 13C NMR (75.48 MHz, CDCl3):
d=159.2, 151.4, 140.3, 136.5, 130.3, 127.6, 127.4, 127.3, 125.3, 120.4, 119.8,
114.1, 55.2, 54.9, 40.5, 31.8, 30.0, 29.5, 29.24, 29.21, 23.7, 22.6, 14.0 ppm;
HRMS (ES+): m/z: calcd for C49H62NaO2 [M+Na]+: 705.4647; found:
705.4640; elemental analysis calcd (%) for C49H62O2 (683.03): C 86.17, H
9.15; found: C 85.53, H 9.14.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)bis[2,1-ethynediyl-4,1-phenylene-
(1E)-2,1-ethenediyl]]bis(N,N-dioctylbenzenamine) (20): Reaction of 18d
(96 mg, 0.206 mmol) with 4a (272 mg, 0.498 mmol), as described for 13a,
for 15 h, with subsequent purification by column chromatography (hep-
tane/CH2Cl2, gradient from 90:10 to 80:20), afforded 223 mg (83%) of
20; 1H NMR (200.13 MHz, CDCl3): d=7.66 (d, J=8.6 Hz, 2H), 7.52 (d,
J=8.6 Hz, 2H), 7.52 and 7.45 (AA’XX’, JAX =8.6 Hz, 8H), 7.50 (s, 2H),
7.38 and 6.62 (AA’XX’, JAX =8.7 Hz, 8H), 7.08 (d, J=16.1 Hz, 2H), 6.86
(d, J=16.1 Hz, 2H), 3.28 (m, 8H), 1.98 (m, 4H), 1.59 (m, 8H), 1.31 (m,
40H), 1.30–1.02 (m, 24H), 0.89 (t, J=6.2 Hz, 12H), 0.83 (t, J=6.7 Hz,
6H), 0.62 ppm (m, 4H); 13C NMR (50.32 MHz, CDCl3): d=151.1, 148.0,
140.6, 138.4, 131.8, 130.7, 129.9, 127.9, 125.8, 125.7, 124.2, 122.8, 122.1,
121.0, 119.9, 111.6, 90.9, 90.3, 55.2, 51.0, 40.4, 31.82, 31.80, 30.0, 29.52,
29.48, 29.31, 29.3, 29.2, 27.3, 27.2, 23.7, 22.64, 22.61, 14.1, 14.0 ppm;
HRMS (LSIMS+, oNPOE): m/z: calcd for C95H132N2 [M+]: 1301.0391;
found: 1301.0381; elemental analysis calcd (%) for C95H132N2 (1302.10): C
87.63, H 10.22, N 2.15; found: C 87.48, H 10.13, N 1.91.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)di-(1E)-2,1-ethenediyl]bis(N,N-
dibutylbenzenamine) (24) and 7-[(1E)-2-[4-(dibutylamino)phenyl]-
A
9,9-Dinonyl-2,7-bis{[4-(octylsulfonyl)phenyl]ethynyl}-9H-fluorene (21a):
Reaction of 18d (106.7 mg, 0.229 mmol) with 8a (174 mg, 0.523 mmol),
as described for 13a, at 458C for 6 h, with subsequent purification by
6.32 mmol) was added to a solution of 22b (2 g, 4.21 mmol) and 3a[94]
(2.56 g, 4.21 mmol) in anhyd CH2Cl2 (50 mL). The mixture was stirred at
208C for 16 h. After addition of water, extraction with CH2Cl2, and
1494
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 1481 – 1498

Quadrupolar Fluorophores
FULL PAPER
drying (Na2SO4), the solvent was evaporated. The residue was filtered
through a short pad of silica gel (CH2Cl2), to afford a mixture, which was
dissolved in Et2O (65 mL). A catalytic amount of I2 was then added and
the solution was stirred at 208C for 16 h under light exposure (75-W
lamp). The organic layer was washed with aq Na2S2O3 and dried
(Na2SO4). After evaporation of the solvent, the compounds were separat-
ed by column chromatography (heptane/CH2Cl2, gradient from 100:0 to
70:30) to yield 430 mg (12%) of 24 and 1.68 g (59%) of 25.
(AA’XX’, JAX =8.5 Hz, 8H), 7.10 (d, J=16.4 Hz, 2H), 7.00 (d, J=
16.4 Hz, 2H), 3.68 (brs, 4H), 2.03 (m, 4H), 1.30–1.10 (m, 24H), 0.87 (t,
6H), 0.70 ppm (m, 4H); 13C NMR (75.48 MHz, CDCl3): d=151.4, 145.9,
140.1, 136.7, 128.4, 127.8, 127.7, 125.8, 125.2, 120.3, 119.7, 115.3, 54.9,
40.6, 31.8, 30.1, 29.5, 29.2, 23.8, 22.8, 22.6, 14.0 ppm; HRMS (LSIMS+,
mNBA): m/z: calcd for C47H60N2 [M+]: 652.4756; found: 652.4733.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)bis
ACHTREUNG
ylene-(1E)-2,1-ethenediyl]]bis(N,N-dihexylbenzenamine)
Data for 24: M.p. 628C; 1H NMR (200.13 MHz, CDCl3): d=7.60 (d, J=
8.0 Hz, 2H), 7.43 (d, J=8.0 Hz, 2H), 7.41 (s, 2H), 7.40 and 6.63
(15 mg, 60% dispersion in mineral oil) was added to a solution of 29c
(124.4 mg, 0.17 mmol) and 4b (149.1 mg, 0.38 mmol) in anhyd THF
(9 mL). The mixture was stirred at 208C for 20 h and the solvent was re-
moved under reduced pressure. After addition of water, extraction with
CH2Cl2, and drying (Na2SO4), the solvents were evaporated. The residue
was purified by column chromatography (heptane/CH2Cl2 80:20) to yield
82.0 mg (53%) of 30; 1H NMR (300.13 MHz, CDCl3): d=7.62 (d, J=
8.3 Hz, 2H), 7.57–7.50 (m, 12H), 7.42 (d, J=8.7 Hz, 4H), 7.25 (d, J=
16.3 Hz, 2H), 7.17 (d, J=16.3 Hz, 2H), 7.10 (d, J=16.2 Hz, 2H), 6.93 (d,
J=16.2 Hz, 2H), 6.66 (d, J=8.7 Hz, 4H), 3.32 (m, 8H), 2.07 (m, 4H),
1.64 (m, 8H), 1.37 (m, 24H), 1.18–1.10 (m, 24H), 0.96 (t, J=6.4 Hz,
12H), 0.85 (t, J=6.9 Hz, 6H), 0.75 ppm (m, 4H); 13C NMR (75.48 MHz,
CDCl3): d=151.5, 147.8, 140.5, 137.6, 136.4, 135.7, 128.8, 128.5, 127.8,
127.7, 126.7, 126.2, 125.5, 124.5, 123.2, 120.7, 120.0, 111.6, 55.0, 51.0, 40.5,
31.8, 31.7, 30.1, 29.5, 29.24, 29.22, 27.3, 26.8, 23.8, 22.7, 22.6, 14.0 ppm;
HRMS (ES+): m/z: calcd for C87H121N2 [M+H]+: 1193.9530; found:
1193.9502.
(AA’XX’,
JAX =8.8 Hz, 8H), 7.09 (d, J=16.3 Hz, 2H), 6.95 (d, J=
16.3 Hz, 2H), 3.30 (m, 8H), 1.99 (m, 4H), 1.58 (m, 8H), 1.37 (m, 8H),
1.24–1.06 (m, 24H), 0.97 (t, J=7.2 Hz, 12H), 0.81 (t, J=6.5 Hz, 6H),
0.69 ppm (m, 4H); 13C NMR (50.32 MHz, CDCl3): d=151.3, 147.6, 139.8,
137.0, 128.0, 127.6, 124.9, 124.7, 124.3, 120.0, 119.5, 111.6, 54.8, 50.7, 40.6,
31.8, 30.1, 29.53, 29.47, 29.2, 23.7, 22.6, 20.3, 14.05, 13.99 ppm; HRMS
(LSIMS+, mNBA): m/z: calcd for C63H92N2 [M+]: 876.7261; found:
876.7258.
Data for 25: M.p. 778C; 1H NMR (200.13 MHz, CDCl3): d=10.04 (s,
1H), 7.85 (d, J=1.5 Hz, 1H), 7.84 (dd, J=8.2 Hz, 1.5, 1H), 7.78 (d, J=
8.2 Hz, 1H), 7.71 (d, J=8.0 Hz, 1H), 7.49 (d, J=8.0 Hz, 1H), 7.44 (s,
1H), 7.41 and 6.64 (AA’XX’, JAX =8.9 Hz, 4H), 7.14 (d, J=16.2 Hz, 1H),
6.96 (d, J=16.2 Hz, 1H), 3.30 (m, 4H), 2.02 (m, 4H), 1.60 (m, 4H), 1.37
(m, 4H), 1.24–1.04 (m, 24H), 0.97 (t, J=7.2 Hz, 6H), 0.82 (t, J=6.6 Hz,
6H), 0.62 ppm (m, 4H); 13C NMR (50.32 MHz, CDCl3): d=192.0, 152.6,
151.5, 147.8, 147.4, 139.2, 137.9, 134.8, 130.5, 129.4, 127.8, 125.1, 124.2,
123.5, 122.7, 121.0, 120.1, 119.5, 111.5, 55.0, 50.6, 40.2, 31.7, 29.8, 29.4,
29.1, 26.3, 23.6, 22.5, 20.2, 14.0. 13.9 ppm; HRMS (LSIMS+, mNBA): m/
z: calcd for C48H69NO [M+]: 675.5379; found: 675.5379.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)bis[(1E)-2,1-ethenediyl-5,2-thio-
A
phenediyl-(1E)-2,1-ethenediyl]]bis(N,N-dioctylbenzenamine) (31): NaH
(48 mg, 60% dispersion in mineral oil) was added to a solution of 29c
(140.5 mg, 0.195 mmol), 6b (225 mg, 0.496 mmol), and [18]crown-6
(10 mg) in anhyd THF (20 mL). The mixture was refluxed for 7 h. After
addition of water, extraction with CH2Cl2, and drying (Na2SO4), the sol-
vents were evaporated. The residue was then purified by column chroma-
tography (heptane/CH2Cl2 90:10) to yield 175 mg (68%) of 31; 1H NMR
(200.13 MHz, CDCl3): d=7.63 (d, J=8.1 Hz, 2H), 7.43 (d, J=8.1 Hz,
2H), 7.41 (s, 2H), 7.33 and 6.61 (AA’XX’, JAX =8.9 Hz, 8H), 7.24 (d, J=
15.9 Hz, 2H), 6.97 (d, J=15.6 Hz, 2H), 6.95 (d, J=15.9 Hz, 2H), 6.94 (d,
J=3.9 Hz, 2H), 6.86 (d, J=3.9 Hz, 2H), 6.83 (d, J=15.6 Hz, 2H), 3.28
(m, 8H), 2.00 (m, 4H), 1.59 (m, 8H), 1.30 (m, 40H), 1.15–1.07 (m, 24H),
0.89 (t, J=6.5 Hz, 12H), 0.82 (t, J=6.7 Hz, 6H), 0.67 ppm (m, 4H);
13C NMR (50.32 MHz, CDCl3): d=151.5, 147.8, 143.2, 140.6, 140.5, 136.1,
129.1, 128.3, 127.7, 127.0, 125.4, 125.3, 124.0, 121.4, 120.4, 119.9, 117.0,
111.6, 54.9, 51.0, 31.8, 30.0, 29.53, 29.50, 29.33, 29.26, 29.23, 27.3, 27.2,
22.65, 22.62, 14.10, 14.07 ppm; HRMS (LSIMS+, mNBA): m/z: calcd for
C91H132N2S2 [M+]: 1316.9832; found: 1316.9837; elemental analysis calcd
(%) for C91H132N2S2 (1318.18): C 82.92, H 10.09, N 2.12, S 4.86; found: C
82.82, H 10.33, N 2.07, S 4.83.
2,7-Bis[(1E)-2-[4-(methylsulfonyl)phenyl]ethenyl]-9,9-dinonyl-9H-fluo-
G
rene (26a): NaH (60 mg, 60% dispersion in mineral oil) was added to a
solution of 22b (237 mg, 0.499 mmol) and 9a[98] (337 mg, 1.1 mmol) in
anhyd THF (15 mL). The mixture was stirred at 208C for 16 h. After ad-
dition of water, extraction with CH2Cl2, and drying (Na2SO4), the solvent
was evaporated. The residue was purified by filtration through a short
pad of silica gel (CH2Cl2), to yield 370 mg (95%) of 26a: M.p. 152–
1
1538C; H NMR (200.13 MHz, CDCl3): d=7.94 and 7.71 (AA’XX’, JAX
=
8.3 Hz, 8H), 7.71 (d, J=8.2 Hz, 2H), 7.54 (d, J=8.1 Hz, 2H), 7.51 (s,
2H), 7.36 (d, J=16.3 Hz, 2H), 7.19 (d, J=16.3 Hz, 2H), 3.09 (s, 6H),
2.04 (m, 4H), 1.25–1.01 (m, 24H), 0.79 (t, J=6.6 Hz, 6H), 0.63 ppm (m,
4H); 13C NMR (50.32 MHz, CDCl3): d=151.7, 142.9, 141.2, 138.5, 135.4,
133.0, 127.8, 126.8, 126.2, 125.8, 121.1, 120.2, 55.0, 44.5, 40.3, 31.7, 29.9,
29.6, 29.4, 29.1, 23.6, 22.5, 14.0 ppm; HRMS (LSIMS+, mNBA): m/z:
calcd for C49H62O4S2 [M+]: 778.4090; found: 778.4096.
2,7-Bis
A
ACHTREUNG
mineral oil) was added to a solution of 22b (66.5 mg, 0.14 mmol) and 11
(115 mg, 0.28 mmol) in anhyd THF (10 mL). The mixture was stirred at
208C for 16 h and the solvent was removed under reduced pressure.
After addition of water, extraction with CH2Cl2, and drying (Na2SO4),
the solvent was evaporated. The residue was purified by column chroma-
tography (CH2Cl2) to yield 87 mg (63%) of 26b; 1H NMR (200.13 MHz,
CDCl3): d=7.93 and 7.70 (AA’XX’, JAX =8.5 Hz, 8H), 7.69 (d, J=8.8 Hz,
2H), 7.58 (m, 8H), 7.52 (d, J=8.8 Hz, 2H), 7.49 (s, 2H), 7.26 (d, J=
16.3 Hz, 2H), 7.25 (s, 4H), 7.16 (d, J=16.3 Hz, 2H), 3.08 (s, 6H), 2.02
(m, 4H), 1.24–1.07 (m, 24H), 0.81 (t, J=6.7 Hz, 6H), 0.67 ppm (m, 4H);
HRMS (LSIMS+, mNBA): m/z: calcd for C65H74O4S2 [M+]: 982.5029;
found: 982.4992.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)bis
dinonyl-9H-fluorenediyl)-(1E)-2,1-ethenediyl]]bis(N,N-dibutylbenzen-
amine) (32): NaH (25 mg, 60% dispersion in mineral oil) was added to a
A
AHCTREUNG
solution of 29c (200 mg, 0.278 mmol) and 25 (414 mg, 0.612 mmol) in
anhyd THF (15 mL). The mixture was stirred at 208C for 16 h and the
solvent was removed under reduced pressure. After addition of water, ex-
traction with CH2Cl2, and drying (Na2SO4), the solvent was evaporated.
The residue was purified by column chromatography (heptane/CH2Cl2,
gradient from 92:8 to 85:15) to yield 410 mg (84%) of 32; 1H NMR
(300.13 MHz, CDCl3): d=7.66 (d, J=7.6 Hz, 2H), 7.64 (s, 2H), 7.63 (d,
J=7.6 Hz, 2H), 7.53 (d, J=8.4 Hz, 2H), 7.52 (s, 2H), 7.52 (d, J=8.0 Hz,
2H), 7.51 (s, 2H), 7.45 and 6.64 (AA’XX’, JAX =8.8 Hz, 8H), 7.41 (d, J=
8.2 Hz, 4H), 7.27 (s, 4H), 7.10 (d, J=16.1 Hz, 2H), 6.97 (d, J=16.1 Hz,
2H), 3.30 (m, 8H), 2.02 (m, 12H), 1.60 (m, 8H), 1.37 (m, 8H), 1.22–1.07
(m, 72H), 0.97 (t, J=7.3 Hz, 12H), 0.81 (t, J=6.8 Hz, 18H), 0.68 ppm
(m, 12H); 13C NMR (75.48 MHz, CDCl3): d=151.5, 151.4, 147.7, 140.8,
140.5, 139.6, 137.3, 136.5, 136.1, 128.6, 128.2, 127.7, 125.7, 125.0, 124.7,
124.3, 120.5, 120.1, 119.8, 111.6, 55.0, 54.9, 50.8, 40.7, 31.7, 30.1, 29.5, 29.3,
29.2, 23.8, 22.6, 20.3, 14.1, 14.0 ppm; HRMS (ES+, CH2Cl2/MeOH): m/z:
calcd for C129H185N2 [M+H]+: 1762.4538; found: 1762.4533; elemental
analysis calcd (%) for C129H184N2 (1762.89): C 87.89, H 10.52, N 1.59;
found: C 88.05, H 10.35, N 1.31.
4,4’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)di-(1E)-2,1-ethenediyl]dibenzen-
amine (28): Air was removed from a solution of 27 (65.9 mg, 0.14 mmol),
4-iodoaniline (1a) (77.0 mg, 0.35 mmol), and K2CO3 (49.9 mg, 0.36 mmol)
in anhyd DMF (3 mL) by blowing argon for 30 min. Then nBu4NCl
(103.9 mg, 0.37 mmol), PPh3 (7.5 mg, 0.029 mmol) and Pd(OAc)2 (3.2 mg,
A
0.014 mmol) were added. Thereafter, the mixture was stirred at 908C for
22 h. The solvent was removed by distillation, and the crude product was
purified by column chromatography (heptane/CH2Cl2 30:70 then 25:75)
to yield 51.0 mg (56%) of 28; 1H NMR (200.13 MHz, CDCl3): d=7.62 (d,
J=7.9 Hz, 2H), 7.44 (d, J=7.9 Hz, 2H), 7.42 (s, 2H), 7.38 and 6.70
Chem. Eur. J. 2007, 13, 1481 – 1498
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
1495

M. Blanchard-Desce, O. Mongin et al.
1,1’-[(9,9-Dinonyl-9H-fluorene-2,7-diyl)bis
phenediyl]]bis(piperidine) (34a): tBuOK (92 mg, 0.82 mmol) was added
to a solution of 22b (129.6 mg, 0.27 mmol) and {[5-(1-piperidinyl)-2-
N
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thienyl]methyl}triphenylphosphonium iodide (357.6 mg, 0.63 mmol) in
A
anhyd CH2Cl2 (4 mL). The mixture was stirred at 208C for 48 h. After
addition of water, extraction with CH2Cl2, and drying (Na2SO4), the sol-
vent was evaporated. The residue was purified by filtration through a
short pad of silica gel (heptane/CH2Cl2 50:50), to afford a mixture of iso-
mers, which was dissolved in Et2O (5 mL). A catalytic amount of I2 was
then added and the solution was stirred at 208C for 3 h under light expo-
sure (75-W lamp). The organic layer was washed with aq Na2S2O3 and
dried (Na2SO4). After evaporation of the solvent, the crude product was
purified by column chromatography (heptane/AcOEt 99:1 then 99:2) to
yield 48.5 mg (22%) of 34a; 1H NMR (200.13 MHz, CDCl3): d=7.64 (d,
J=7.9 Hz, 2H), 7.49 (d, J=7.9 Hz, 2H), 7.41 (s, 2H), 7.21 (d, J=16.5 Hz,
2H), 7.18 (d, J=5.7 Hz, 2H), 6.97 (d, J=16.5 Hz, 2H), 6.92 (d, J=
5.7 Hz, 2H), 2.97 (m, 8H), 1.98 (m, 4H), 1.78 (m, 8H), 1.59 (m, 4H),
1.25–1.07 (m, 24H), 0.81 (t, J=6.6 Hz, 6H), 0.72 ppm (m, 4H); 13C NMR
(50.32 MHz, CDCl3): d=156.4, 151.5, 140.1, 136.9, 127.3, 127.2, 124.8,
124.1, 120.8, 120.7, 119.7, 117.2, 56.3, 54.8, 40.4, 31.8, 30.1, 29.6, 29.3, 29.2,
26.1, 23.9, 22.6, 14.1 ppm; HRMS (LSIMS+, mNBA): m/z: calcd for
C53H72N2S2 [M+]: 800.5137; found: 800.5149; elemental analysis calcd
(%) for C53H72N2S2 (801.30): C 79.44, H 9.06, N 3.50, S 8.00; found: C
79.66, H 9.42, N 3.22, S 7.70.
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phenediyl-(1E)-2,1-ethenediyl-5,2-thiophenediyl]]bis(piperidine) (34b):
Reaction of 33 (77.0 mg, 0.11 mmol) with {[5-(1-piperidinyl)-2-thienyl]-
methyl}triphenylphosphonium iodide (140.0 mg, 0.25 mmol), as described
for 34a, with subsequent purification by column chromatography (hep-
tane/CH2Cl2, gradient from 70:30 to 40:60), afforded 20.2 mg (18%) of
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1
34b; H NMR (300.13 MHz, CDCl3): d=7.64 (d, J=8.0 Hz, 2H), 7.45 (d,
J=8.0 Hz, 2H), 7.41 (s, 2H), 7.25 (d, J=15.9 Hz, 2H), 7.08 (d, J=5.4 Hz,
2H), 6.99 (d, J=15.9 Hz, 2H), 6.98 (s, 4H), 6.96 (d, J=3.8 Hz, 2H) 6.89
(d, J=3.8 Hz, 2H), 6.85 (d, J=5.4 Hz, 2H), 2.95 (m, 8H), 2.00 (m, 4H),
1.80 (m, 8H), 1.59 (m, 4H), 1.26–1.05 (m, 24H), 0.82 (t, J=6.8 Hz, 6H),
0.66 ppm (m, 4H); 13C NMR (75.48 MHz, CDCl3): d=156.8, 151.6, 142.9,
141.4, 140.6, 136.0, 128.7, 127.0, 126.6, 126.1, 125.4, 123.9, 121.6, 121.3,
120.5, 120.0, 119.9, 116.4, 56.3, 55.0, 40.6, 31.8, 30.1, 29.5, 29.3, 29.2, 26.2,
23.9, 23.8, 22.6, 14.1 ppm; HRMS (ES+, MeOH): m/z: calcd for
C65H81N2S4 [M+H]+: 1017.5283; found: 1017.5268.
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Acknowledgements
We acknowledge financial support from Rennes MØtropole and DØlØga-
tion GØnØrale pour lꢁArmement (DGA Grant 00.34.070.00.470.75.653).
L.P. and M.C. received fellowships from MENESR and DGA, respective-
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Published online: November 14, 2006
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