Theoretical and Experimental Study on Boron β-Diketonate Complexes with Intense Two-Photon-Induced Fluorescence in Solution and in the Solid State

Article abstract of DOI:10.1002/cphc.201600178

Three boron diketonate chromophores with extended π-conjugated backbone were prepared and their spectroscopic features were investigated through a combined theoretical/experimental study. It was shown that these complexes, which undergo very large electro

Full text of DOI:10.1002/cphc.201600178

DOI: 10.1002/cphc.201600178
Articles
Theoretical and Experimental Study on Boron
b-Diketonate Complexes with Intense Two-Photon-Induced
Fluorescence in Solution and in the Solid State
Pierre-Henri Lanoꢀ,[a] Bastien Mettra,[a] Yuan Yuan Liao,[a] Nathalie Calin,[a] Anthony D’Alꢁo,*[b]
Tomotaka Namikawa,[c] Kenji Kamada,[c] Frꢁderic Fages,[b] Cyrille Monnereau,*[a] and
Chantal Andraud*[a]
Three boron diketonate chromophores with extended p-conju-
gated backbone were prepared and their spectroscopic fea-
tures were investigated through a combined theoretical/exper-
imental study. It was shown that these complexes, which un-
dergo very large electronic reorganization upon photoexcita-
tion, combine large two-photon absorption cross section with
an emission energy and quantum efficiency in solution that is
strongly dependent on solvent polarity. The strong positive in-
fluence of boron complexation on the magnitude of the two-
photon absorption was clearly established, and it was shown
that the two-photon absorption properties were dominated by
the quadrupolar term. For one of the synthesized compounds,
intense one- and two-photon-induced solid-state emission
(fluorescence quantum yield of 0.65 with maximum wave-
length of 610 nm) was obtained as a result of antiparallel J-ag-
gregate crystal packing.
1. Introduction
Chromophores that combine large two-photon absorption
cross sections with high solid-state fluorescence quantum
yields are valuable candidates for applications ranging from
optoelectronics (upconversion lasing) to biophotonics (ultra-
bright nanosized fluorescent contrast agent).[1] Yet, reports on
such molecules are relatively scarce in the literature.[2]
thus avoiding the formation of aggregates, which are in the
most general cases detrimental to emission efficiency.[5]
In parallel, the two-photon-induced fluorescence (TPIF) prop-
erties of various boron complexes have been quite extensively
studied by different groups. Besides archetypical boron–dipyr-
romethene (BODIPY), used in bioimaging since the early 2000s
and almost immediately investigated in the context of TPIF,[6]
other types of boron compounds, particularly trivalent ones,
have received considerable attention.[7] In 2003 and 2004 suc-
cessive reports by the groups of Marder and Blanchard-Desce
showed that fluorophores based on b-(diketonato)boron moi-
eties displayed, in spite of a short p-conjugated backbone, un-
expectedly large cross section values up to 200 GM (Gçppert
Meyer unit, 1 GM=10ꢀ50 cm4 sphotonꢀ1).[8]
It was recently established by different groups that boron di-
fluoride complexes of a variety of organic ligands present ex-
ceptional solid-state luminescence properties.[3] It has been
proposed that these exceptional features are most likely a con-
sequence of restrictions of the rotational/torsional mobility
arising from the formation of a boron chelate.[4] Alternatively, it
has also been suggested that steric hindrance induced by the
substituents attached to the boron complex can also partici-
pate in reducing molecular interactions in the crystal packing,
As a consequence, it can be anticipated that similar boron
complexes could constitute an interesting basis to be used as
two-photon solid-state emitters. Indeed, recent studies by
D’Alꢁo, Fages, and co-workers have clearly established that
borylated curcuminoid derivatives are particularly attractive
candidates in this regard, as they combine relatively large two-
photon cross sections with significant fluorescence quantum
yields in solution and in the solid state, with emission that can
reach the near-IR region in the condensed phase.[4f,9]
[a] Dr. P.-H. Lanoꢀ, Dr. B. Mettra, Dr. Y. Y. Liao, Dr. N. Calin, Dr. C. Monnereau,
Dr. C. Andraud
Laboratoire de Chimie UMR CNRS 5182
Ecole Normale Supꢁrieure de Lyon/Universitꢁ de Lyon
46 Allꢁe d’Italie, 69007 Lyon (France)
E-mail: cyrille.monnereau@ens-lyon.fr
chantal.andraud@ens-lyon.fr
[b] Dr. A. D’Alꢁo, Prof. F. Fages
CINAM UMR CNRS 7325
In the present paper, we show that a boron complex of 1,3-
diphenylpropane-1,3-dione—a scaffold that has already been
used in the context of solid-state fluorescent materials[10]—for
which both phenyl groups are halogenated in their para posi-
tions, can be used as a convenient and highly reactive elec-
tron-deficient synthetic intermediate towards a variety of two-
photon-absorbing boron diketonate complexes with tunable
absorption and emission wavelengths (labs and lem). We took
Universitꢁ Aix-Marseille
Campus de Luminy, Case 913, 13288 Marseille (France
E-mail: daleo@cinam.univ-mrs.fr
[c] T. Namikawa, Prof. K. Kamada
IFMRI
National Institute of Advanced Industrial Science and Technology (AIST)
Ikeda, Osaka 563-8577 (Japan)
Supporting Information for this article can be found under http://
dx.doi.org/10.1002/cphc.201600178.
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advantage of this approach to introduce three different end
groups with varying electron-donating abilities, namely,
a strong dialkylaniline donor, a weaker alkoxyphenyl moiety,
and an intermediate alkoxyfluorene; these groups constitute
some of the most archetypical electron-donating groups used
in nonlinear optical chromophores. As a consequence of their
electronic dissymmetry, the resulting compounds possess sig-
nificantly large two-photon absorption cross sections, above
1000 GM for the best compound within the series. Their fluo-
rescence is highly solvatochromic, and its efficiency is very de-
pendent on the polarity of the solvent. For one of these com-
plexes, 6b, a very intense solid-state emission centered around
610 nm is obtained by using both one- and two-photon excita-
tion, which is in good compliance with bioimaging require-
ments. The origin of this luminescence is discussed on the
basis of its crystal-packing parameters, and we show that it
can be achieved by using either one- or two-photon
excitation.
noate followed by acidolysis afforded diketone ligand 3, which
was involved in complexation with boron trifluoride to afford
target intermediate 4 in a satisfactory overall yield of 66%.
Target chromophores 6a, 6b, and 6c were finally obtained
through a very efficient Sonogashira cross-coupling step with
alkynes 5a,[12] 5b,[13] and 5c, respectively.[14] Owing to the pres-
ence of the strong electron-withdrawing boron diketonate
group, this last step, which usually requires relatively strong
heating over several hours, was readily achieved in a couple of
minutes at room temperature. In the cases of 6a and 6b, the
target chromophores precipitated during the course of the re-
actions and were isolated in good yields and with good analyt-
ical purities after simple filtration and precipitation in a di-
chloromethane/pentane mixture. For 6c, additional column
chromatography was required. In all cases, the identities and
purities of the compounds were confirmed by a variety of ana-
lytical techniques (see Sections S1–S5 in the Supporting
Information).
2.2. Spectroscopy
2. Results and Discussion
The spectroscopic features of these three complexes in solu-
tions were then investigated in detail (the data are gathered in
Table 1). In all cases, broad structureless absorption bands
were observed, characteristic of an intramolecular charge
transfer (ICT) electronic transition (see Sections S8–S10).[15] For
all compounds, the absorption band was slightly affected by
the solvent’s polarity, whereas all the chromophores displayed
marked positive solvatochromism of their emission (Figure 1).
This clearly indicated a strong increase in their dipole moments
between their ground and excited states,[16] which could only
2.1. Synthesis
The syntheses of all target molecules (Scheme 1) relied on
a similar strategy that involved key intermediate boron com-
plex 4, which we obtained through a classical literature proce-
dure.[11] First, condensation of commercially available p-bromo-
benzaldehyde and (p-bromophenyl)methyl ketone by using
the standard Claisen–Schmidt procedure afforded b-enone 1.
This compound was then treated with bromine to afford addi-
tion product 2. Reaction of compound 2 with sodium metha-
Scheme 1. Synthesis of compounds 6a–c.
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Table 1. Main spectroscopic features of compounds 6a–c in solution.
Compd
Solvent
labs [nm]
lem [nm]
Ff[a]
Stokes [cmꢀ1
]
6a[b]
cyclohexane
1,4-dioxane
toluene
520
510
515
540
426
440
442
448
455
442
436
440
450
458
462
468
472
462
544
672
620
753
465
504
487
542
568
563
553
628
497
575
543
666
707
694
0.72
0.30
0.62
0.05
0.69
1
850
4730
3290
5240
1970
2890
2090
3870
4370
4860
4850
6800
2100
4440
3230
6350
7040
7230
CHCl3
6b[34]
cyclohexane
1,4-dioxane
toluene
CHCl3
1,2-dichlorobenzene
THF
EtOAc
MeOH
cyclohexane
dioxane
toluene
1
1
0.94
0.88
0.91
0.018
0.74
0.68
0.74
0.25
<0.01
0.025
6c[c]
CHCl3
1,2-dichlorobenzene
THF
[a] Rubren in methanol was used as a reference (Ff =0.27). [b] No fluorescence observed in dichlorobenzene, EtOAc, THF, or MeOH. [c] No fluorescence ob-
served in EtOAc or MeOH.
be related to transfer of electron density from the peripheral
donor groups to the central boron diketonate moiety. A
Mataga–Lippert plot[17] of the Stokes shift of compound 6b
versus the solvent polarity allowed us to estimate the dipole
moment variation between the ground and excited states
(Dmge) to be about 18 D, which confirmed this hypothesis.
Beside this emission solvatochromism, the emission quan-
tum efficiency also showed a strong dependence on the sol-
vent’s polarity. As a general statement, upon increasing the sol-
vent polarity, a marked decrease in the luminescence efficiency
was observed. This behavior, sometimes referred to as “positive
solvatokinetics”,[18] is classical behavior for such charge-transfer
(CT) chromophores and can be attributed to increased vibronic
contributions to the nonradiative de-excitation pathways as
the emission energy is decreased.[18,19] It was previously report-
ed, and found to be particularly marked, in other boron
complexes.[20]
mophores with large Stokes shifts, it is well documented that
excited-to-ground-state vibronic couplings can play an impor-
tant role in nonradiative decay of the excited state at low
emission energies, which often results in important lumines-
cence quenching.[21] In the present case, this led to a rapid de-
crease in the emission of the studied compounds above a cer-
tain threshold, typically located between wavelengths of 600
and 650 nm.
Whereas 6b displayed distinctively high solid-state emission
(Figure 2), with a quantum yield of 0.65 and a maximum emis-
sion wavelength of 610 nm, the other two complexes did not
display any detectable solid-state emission. In addition to the
abovementioned ground-to-excited-state vibronic coupling, in-
termolecular vibrational and dipolar coupling processes may
also contribute to emission quenching in the solid state in the
latter.[22]
The extent of this emission quenching process turned out to
be markedly dependent on the substitution parameters (Fig-
ure S11). Thus, whereas methoxy-substituted 6b presented
a fluorescence quantum yield (Ff) that remained high in a vari-
ety of solvents with polarities ranging from cyclohexane to
ethyl acetate, the drop in luminescence quantum efficiency
was much more pronounced in the case of dialkylamino-termi-
nated compound 6a, the emission of which was the most red-
shifted within the series: a rapid drop in the fluorescence
quantum efficiency was observed upon going from cyclo-
hexane (0.72) to dioxane (0.28) and dichloromethane (0.05),
and fluorescence was not observed in solvents of higher
polarities.
2.3. Crystal Structure
Crystals suitable for X-ray diffraction were obtained as long,
thin, bright orange-like needles by slow diffusion of diisopropyl
ether into a chloroform solution of 6b. An orthorhombic crys-
tal structure was obtained. Its main crystal parameters are
summarized in Section S17.
The crystal structure shows that, as expected, the molecule
consists of an essentially flat V-shaped p-conjugated backbone,
in which the two oxygen atoms of the central b-diketonate
moieties complex a single boron atom. Fluoride substituents
lie in a plane orthogonal to the plane of the rest of the mole-
cule. An attractive interaction seem to take place between the
fluoride groups and the aromatic protons of the neighboring
chromophore, as illustrated by the presence of short contact
distances (2.40 ꢃ, compared with the sum of van der Waals
radii, 2.67 ꢃ; Figure 3b). Such H···F bonds of similar lengths
have been thoroughly reported and described in the past,[23]
Moreover, intermediate behavior was observed for 6c, for
which fluorescence was not seen in ethyl acetate or methanol.
This suggested that, more than the solvent’s polarity, the posi-
tion of the maximum emission wavelength determined the ef-
ficiency of the fluorescence process. Indeed, for such CT chro-
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Figure 1. Emission spectra of a) compound 6a, b) compound 6b, and
c) compound 6c in solvents of different polarities.
Figure 3. Crystal structure of compound 6b. a) Structure of an individual
molecule of 6b within its crystal cell; hydrogen atom are omitted for clarity.
b) Close up of the H···-F short contact; (methoxy)phenylethynyl moieties are
omitted for clarity. c) Crystal packing diagram of 6b shown down the direc-
tion of the b axis.
polar interactions classically encountered in such boron diketo-
nate complexes, to stabilizing the antiparallel and partly offset
stacking of molecules along the b axis of the cell, with an inter-
planar distance of 3.49 ꢃ (Figure 3c).
Figure 2. Crystalline powder sample of 6b under left) natural and right) UV-
A (l=365 nm) light.
including in related dioxazoborine-based compounds;[24] in the
present case, it certainly contributes, along with the strong di-
This kind of “antiparallel J-aggregate” configuration accounts
for the high luminescence efficiency of the solid, in agreement
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with published works,[25] including examples on related boron
diketonate complexes.[26]
2.4. Two-Photon Absorption
Two-photon cross sections were then systematically evaluated
for compounds 6a–c by using TPIF spectroscopy.[27] In the
cases of compounds 6a and 6c, for which the two-photon
spectrum envelope exceeded the limit of the working wave-
length of the laser used for the TPIF measurements, the two-
photon absorption cross section values were cross-checked by
an additional Z-scan measurement[28] to fill the missing points
and ascertain the accuracy of the TPIF measurement. Toluene
was used as a common solvent for the entire study, as all com-
plexes possessed good emission efficiency in this solvent,
which thus facilitated the TPIF measurements. All three com-
plexes displayed significantly high two-photon cross section
values, in the range of 200 to 1300 GM (Figure 4). As expected,
an increase in the strength of the terminal electron donor or in
the conjugation length resulted in an enhancement in the
cross section value. This trend was, however, particularly
marked here: dialkylamino-substituted 6a possessed a cross
section (1300 GM) almost one order of magnitude higher than
that of its methoxy counterpart 6b (170 GM), whereas substi-
tution of the phenyl group by a fluorenyl group in 6c resulted
in a threefold increase in the two-photon efficiency (570 GM).
Comparison between the one- and two-photon absorption
spectra of all complexes showed unambiguously that the two-
photon transition was systematically blueshifted relative to
that of the one-photon transition; thus, the one- and two-
photon transitions are mutually exclusive. This behavior is gen-
erally associated with centrosymmetric chromophores, in
which the zero permanent dipole moment cancels the dipolar
term in the third-order hyperpolarizability equation.[29] Strictly,
the molecules studied here are not centrosymmetric; neverthe-
less, the blueshift suggests that the quadrupolar term is domi-
nant in the two-photon absorption processes of 6a–c. Similar
observations have already been reported for other V-shaped
chromophores such as various polymethines[30] and (aza)-
BODIPY derivatives,[6b] and this trend seems to be a general
characteristic of curcuminoids and diketonate boron
complexes.[31]
2.5. Theoretical Calculations
To clarify the nature of the transitions involved in the one- and
two-photon processes, quantum-chemical calculations were
performed for model molecules 6a’ and 6c’, in which the
hexyl groups of 6a and 6c were replaced with methyl groups
to save computational costs (Figures 5 and S16). Geometry op-
timization and calculations of the excited states were per-
formed in the gas phase at the B3LYP//6-31G(d) level of theory
with the Gaussian09 program (details of the calculation results
and the geometries are given in the Supporting Information,
see Section S16). As shown in Figure 5, the first intense two-
photon absorption (TPA) transition can be assigned to the
transition from the ground state to the S2 excited state that
Figure 4. Two-photon absorption spectra by TPIF (red marks) overlapped
with the corresponding one-photon absorption spectrum (full, black) for
compounds 6a–c in toluene. For compounds 6a and 6b, accuracy of the
TPIF measurement was ascertained by a complementary Z-scan measure-
ment (blue marks). The typical Z-scan traces can be found in Figures S15-
1 and S15-2. sTPA =two-photon absorption cross section; e=molar extinction
coefficient.
has gerade-like symmetry against the vertical symmetric plane
of the molecule, whereas the first and third excited states (S1
and S3) have ungerade-like symmetry and are responsible for
the one-photon absorption (OPA) bands. These calculations
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Figure 5. Structures of model compounds 6a’ and 6c’ with the orbital patterns involved in the optical transitions to the first three excited states [transition
energy, oscillator strength (f), and approximate symmetry are shown in parentheses]. The number next to the arrow stands for the orbital component of the
configuration to the transition. The u and g attached to the orbital names are the approximate symmetries, that is, ungerade- and gerade-like, respectively,
against the vertical symmetry plane of the molecule.
clearly ascertained the CT character of the one- and two-
photon transitions, with a shift in the electronic density from
the peripheral donors to the central boron complex.
obtain additional insight into the influence of symmetry
(Figure 6). The absorption and emission profiles of 7 and 8 in
various solvents are given in Sections S12 and S13.
The energy of the OPA-allowed lowest-lying excited state
(S1) was nicely reproduced [e.g. calcd value of 2.316 eV for 6a’
vs. exptl values of 2.26 (in dichlorobenzene) to 2.43 eV (in diox-
ane) for 6a], and calculations showed that this transition pos-
sessed dominant HOMO!LUMO (with symmetry inversion, i.e.
ungerade-like) character. Conversely, the second lowest lying
excited state (S2) mainly corresponded to a HOMOꢀ1!LUMO
(with symmetry conservation, i.e. gerade-like) electronic transi-
tion, the energy of which closely matched our experimental
value for the two-photon transition [e.g. calcd value of 2.54 eV
for 6a’ vs. exptl values of 2.58 (TPIF) and 2.64 eV (Z-scan) for
6a], which confirmed the dominant quadrupolar nature of the
electronic transitions. The above discussion is limited to the
planar structure, as obtained by the geometrical optimization.
However, rotational motion around the triple bond can be acti-
vated at room temperature. Thus, we checked the influence of
rotational motion of the end groups on the optical properties
by calculating some selected rotational conformers. These re-
sults clarified that rotation from the planar structure diminishes
the one- and two-photon absorption bands because of de-
creasing overlap of the orbital (see Section S16 for details),
which suggests that the planar and planar-like structures are
responsible for the observed TPA band.
The two-photon absorption cross sections of both molecules
were evaluated by TPIF spectroscopy (Figure 7). The beneficial
influence of boron complexation on the TPA efficiency of the
molecule was clear, as the TPA cross section dropped by
almost one order of magnitude upon going from 6a
(1300 GM) to 7 (200 GM). This effect may arise from the largely
increased electron-withdrawing ability that results from boron
complexation but also from stabilization of the fully conjugat-
ed enol, relative to the ligand, in which both the enol and
ketol forms may coexist. The second hypothesis seems to be
1
ruled out by examination of the H NMR spectrum of the latter,
which clearly reveals the exclusive presence of a single methyl-
ene proton signal associated to the enol form at a chemical
shift (d=6.89 ppm) that is not markedly different from that of
the complex (d=7.15 ppm), and in close match with that in
the literature.[11] This indicates that the enol form is also pre-
dominant in the ligand.
In contrast, dipolar compound 8 displayed a two-photon ef-
ficiency (90 GM) that was lowered only by a factor of two rela-
tive to that of its quadrupolar counterpart 7 (200 GM), which,
given the difference in size between both compounds, corre-
sponds to a very similar two-photon efficiency per p electron.
However, a difference exists in the nature of the transition in-
volved in both cases, as 8 shows superimposition of its one-
photon and two-photon transitions, whereas the two-photon
spectrum was significantly blueshifted in the case of 7, as it
was in complex 6a. This is in good agreement with an elec-
tronic transition fully delocalized over the entire chromophore
backbone, which gives it pseudoquadrupolar character; this is
consistent with the purely enol nature of the molecule as sug-
gested above.
2.6. Comparison with Benchmark Compounds
With the aim to evaluate the influence of boron complexation
on the two-photon absorption cross sections of the complexes,
we synthesized compound 7 (see Section S2 and S6), a non-
borylated analogue of 6a (most efficient complex within the
series in terms of two-photon efficiency).
Moreover, compound 8 (see Section S2 and S7) was also
evaluated as a dipolar counterpart of 7, which allowed us to
Finally, we tested the relevance of our approach for applica-
tions requiring two-photon solid-state emitters. To this end,
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Figure 7. Solid-state one-photon (black, full) and two-photon (red marks) ex-
citation and emission (black, dotted) spectra of a powdered sample of 6b.
Solid-state emission upon one-photon excitation is featured as a dotted
gray line for comparison.
3. Conclusions
In the course of this study, we synthesized three new diketo-
nate boron complexes as potential candidates for applications
dealing with two-photon-induced solid-state emission.
Through a detailed spectroscopic study we clearly established
that all three compounds display intense two-photon absorp-
tion (200 to 1200 GM) in the near-IR range (l=700–1100 nm),
along with emission quantum yields that exceed 0.6 and that
can reach unity in toluene. However, this luminescence was
found to be extremely sensitive to environmental parameters,
such as solvent polarity and solid-state interactions. These re-
sults were rationalized on the basis of theoretical calculations,
which clearly ascertained the strong charge-transfer character
!
of the low-energy electronic transition (S1 S0) and the domi-
nant quadrupolar character of the two-photon-allowed transi-
!
tion (S2 S0). This last feature was also confirmed by comple-
mentary spectroscopic measurements and comparisons on
model compounds 7 and 8, which also clearly established the
importance of boron complexation in the magnitude of the
two-photon absorption cross section.
For one of the complexes, that is, 6b, intense solid-state
emission with a quantum yield of 0.65 could be achieved. TPIF
measurements were performed on a crystalline powder sample
of this complex: a very intense TPIF signal was obtained,
which further demonstrated the applicability of complex 6b as
a two-photon solid-state emitter. More specifically, because of
its orange-red fluorescence, and because of the tremendous
interest and growing use of curcuminoid complexes in the
framework of biomedical applications,[33] we believe that 6b[34]
could constitute a very appealing chromophore towards the
making of organic nanoparticles for two-photon laser scanning
microscopy bioimaging.
Figure 6. Structure and overlaid one- and two-photon absorption spectra in
toluene for benchmark compounds a) 7 and b) 8.
a powder sample of compound 6b was compressed into
a tablet, which was placed in a TPIF setup. By varying the inci-
dent laser wavelength, we were able to obtain a solid-state
two-photon excitation spectrum (Figure 7).[32] In contrast with
the one-photon excitation spectrum, which showed a broad
structureless band, characteristic of molecular aggregates, the
spectrum consisted in a narrow band, the maximal two-
photon excitation wavelength of which was centered around
790 nm, in close match with the solution data.
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Y. Poon, W.-Y. Wong, F. Ibersiene, S. Fathallah, A. Boucekkine, J.-F. Halet,
T. B. Marder, J. Mater. Chem. 2009, 19, 7532–7544.
Acknowledgements
[8] a) M. Halik, W. Wenseleers, C. Grasso, F. Stellacci, E. Zojer, S. Barlow, J.-L.
Bredas, J. W. Perry, S. R. Marder, Chem. Commun. 2003, 1490–1491; b) E.
Cognꢁ-Laage, J.-F. Allemand, O. Ruel, J.-B. Baudin, V. Croquette, M. Blan-
chard-Desce, L. Jullien, Chem. Eur. J. 2004, 10, 1445–1455.
[9] a) A. D’Alꢁo, A. Karapetyan, V. Heresanu, M. Giorgi, F. Fages, Tetrahedron
2015, 71, 2255–2259; b) A. D’Alꢁo, D. Gachet, V. Heresanu, M. Giorgi, F.
Fages, Chem. Eur. J. 2012, 18, 12764–12772.
This work was partially supported by the Ministry of Education,
Culture, Sports, Science and Technology (MEXT), Japan, through
a Grant-in-Aid for Scientific Research on Innovative Areas “Stimu-
li-Responsive Chemical Species” (no. 25109544 to K.K.). P.H.L. ac-
knowledges the ANR P3N Program (ANR-09-NANO-027–04,
NanoPDT) for a postdoctoral grant.
[10] G. Zhang, J. P. Singer, S. E. Kooi, R. E. Evans, E. L. Thomas, C. L. Fraser, J.
Mater. Chem. 2011, 21, 8295–8299.
[11] G. E. Southard, G. M. Murray, J. Org. Chem. 2005, 70, 9036–9039.
[12] a) A. Scarpaci, C. Monnereau, N. Hergue, E. Blart, S. Legoupy, F. Odobel,
A. Gorfo, J. Perez-Moreno, K. Clays, I. Asselberghs, Dalton Trans. 2009,
4538–4546; b) C. Monnereau, E. Blart, F. Odobel, Tetrahedron Lett. 2005,
46, 5421–5423.
Keywords: boron · chromophores · fluorescence · solid-state
emission · theoretical calculations
[13] Y. Yamaguchi, T. Ochi, S. Miyamura, T. Tanaka, S. Kobayashi, T. Wakamiya,
Y. Matsubara, Z.-i. Yoshida, J. Am. Chem. Soc. 2006, 128, 4504–4505.
[14] A. Picot, C. Feuvrie, C. Barsu, F. Malvolti, B. Le Guennic, H. Le Bozec, C.
Andraud, L. Toupet, O. Maury, Tetrahedron 2008, 64, 399–411.
[15] D. V. Matyushov, M. D. Newton, J. Phys. Chem. A 2001, 105, 8516–8532.
[16] C. Reichardt, Chem. Rev. 1994, 94, 2319–2358.
[17] a) E. Lippert, Ber. Bunsen-Ges. Phys. Chem. 1957, 61, 962–975; b) N.
Mataga, Y. Kaifu, M. Koizumi, Bull. Chem. Soc. Jpn. Bull. Chem. Soc. Jpn
1956, 29, 465–470.
[1] a) J. Massin, W. Dayoub, J.-C. Mulatier, C. Aronica, Y. Bretonniꢄre, C. An-
draud, Chem. Mater. 2011, 23, 862–873; b) S. Varghese, S. Das, J. Phys.
Chem. Lett. 2011, 2, 863–873.
[2] a) F. Gao, Q. Liao, Z.-Z. Xu, Y.-H. Yue, Q. Wang, H.-L. Zhang, H.-B. Fu,
Angew. Chem. Int. Ed. 2010, 49, 732–735; Angew. Chem. 2010, 122,
744–747; b) S. L. Oliveira, D. S. CorrÞa, L. Misoguti, C. J. L. Constantino,
R. F. Aroca, S. C. Zilio, C. R. MendonÅa, Adv. Mater. 2005, 17, 1890–1893;
c) F. He, L. L. Tian, X. Y. Tian, H. Xu, Y. H. Wang, W. J. Xie, M. Hanif, J. L.
Xia, F. Z. Shen, B. Yang, F. Li, Y. G. Ma, Y. Q. Yang, J. C. Shen, Adv. Funct.
Mater. 2007, 17, 1551–1557.
[18] R. Lapouyade, A. Kuhn, J.-F. Letard, W. Rettig, Chem. Phys. Lett. 1993,
208, 48–58.
[3] K. Tanaka, Y. Chujo, NPG Asia Mater 2015, 7, e223.
[19] a) G. Zhang, S. Kim, R. Evans, B. Kim, J. N. Demas, C. Fraser, J. Fluoresc.
2009, 19, 881–889; b) J. Massin, A. Charaf-Eddin, F. Appaix, Y. Breton-
niere, D. Jacquemin, B. van der Sanden, C. Monnereau, C. Andraud,
Chem. Sci. 2013, 4, 2833–2843.
[4] a) W. Li, W. Lin, J. Wang, X. Guan, Org. Lett. 2013, 15, 1768–1771; b) K.
Benelhadj, J. Massue, P. Retailleau, G. Ulrich, R. Ziessel, Org. Lett. 2013,
15, 2918–2921; c) C.-W. Liao, R. Rao, M, S.-S. Sun, Chem. Commun. 2015,
51, 2656–2659; d) Y. Meesala, V. Kavala, H.-C. Chang, T.-S. Kuo, C.-F. Yao,
W.-Z. Lee, Dalton Trans. 2015, 44, 1120–1129; e) Y.-L. Rao, S. Wang,
Inorg. Chem. 2011, 50, 12263–12274; f) A. D’Alꢁo, V. Heresanu, M.
Giorgi, B. Le Guennic, D. Jacquemin, F. Fages, J. Phys. Chem. C 2014,
118, 11906–11918; g) Y. Zhou, Y. Xiao, S. Chi, X. Qian, Org. Lett. 2008, 10,
633–636.
[5] a) M. Elbing, G. C. Bazan, Angew. Chem. Int. Ed. 2008, 47, 834–838;
Angew. Chem. 2008, 120, 846–850; b) H. Lu, Q. Wang, L. Gai, Z. Li, Y.
Deng, X. Xiao, G. Lai, Z. Shen, Chem. Eur. J. 2012, 18, 7852–7861; c) G.-
L. Fu, H.-Y. Zhang, Y.-Q. Yan, C.-H. Zhao, J. Org. Chem. 2012, 77, 1983–
1990; d) A. D’Alꢁo, F. Fages, Disp. Imaging 2014, 1, 149–174.
[6] a) P. Didier, G. Ulrich, Y. Mely, R. Ziessel, Org. Biomol. Chem. 2009, 7,
3639–3642; b) P.-A. Bouit, K. Kamada, P. Feneyrou, G. Berginc, L. Toupet,
O. Maury, C. Andraud, Adv. Mater. 2009, 21, 1151–1154; c) N. Meltola, A.
Soini, P. Hꢅnninen, J. Fluoresc. 2004, 14, 129–138; d) F. Bestvater, E.
Spiess, G. Stobrawa, M. Hacker, T. Feurer, T. Porwol, U. Berchner-
Pfannschmidt, C. Wotzlaw, H. Acker, J. Microsc. 2002, 208, 108–115; e) L.
Porrꢄs, O. Mongin, M. Blanchard-Desce, Tetrahedron Lett. 2006, 47,
1913–1917.
[7] a) J. C. Collings, S.-Y. Poon, C. Le Droumaguet, M. Charlot, C. Katan, L.-O.
Pꢆlsson, A. Beeby, J. A. Mosely, H. M. Kaiser, D. Kaufmann, W.-Y. Wong,
M. Blanchard-Desce, T. B. Marder, Chem. Eur. J. 2009, 15, 198–208; b) Z.-
Q. Liu, Q. Fang, D.-X. Cao, D. Wang, G.-B. Xu, Org. Lett. 2004, 6, 2933–
2936; c) Z.-Q. Liu, M. Shi, F.-Y. Li, Q. Fang, Z.-H. Chen, T. Yi, C.-H. Huang,
Org. Lett. 2005, 7, 5481–5484; d) A. Hayek, J.-F. Nicoud, F. Bolze, C.
Bourgogne, P. L. Baldeck, Angew. Chem. Int. Ed. 2006, 45, 6466–6469;
Angew. Chem. 2006, 118, 6616–6619; e) M. Charlot, L. Porres, C. D. En-
twistle, A. Beeby, T. B. Marder, M. Blanchard-Desce, Phys. Chem. Chem.
Phys. 2005, 7, 600–606; f) A. Hayek, F. Bolze, C. Bourgogne, P. L. Bal-
deck, P. Didier, Y. Arntz, Y. Mꢁly, J.-F. Nicoud, Inorg. Chem. 2009, 48,
9112–9119; g) Z.-q. Liu, Q. Fang, D. Wang, D.-x. Cao, G. Xue, W.-t. Yu, H.
Lei, Chem. Eur. J. 2003, 9, 5074–5084; h) P. Chen, A. S. Marshall, S.-H.
Chi, X. Yin, J. W. Perry, F. Jꢅkle, Chem. Eur. J. 2015, 21, 18237–18247; i) L.
Ji, Q. Fang, M.-s. Yuan, Z.-q. Liu, Y.-x. Shen, H.-f. Chen, Org. Lett. 2010,
12, 5192–5195; j) Z.-q. Liu, Q. Fang, D. Wang, G. Xue, W.-t. Yu, Z.-s.
Shao, M.-h. Jiang, Chem. Commun. 2002, 2900–2901; k) L. Ji, R. M.
Edkins, L. J. Sewell, A. Beeby, A. S. Batsanov, K. Fucke, M. Drafz, J. A. K.
Howard, O. Moutounet, F. Ibersiene, A. Boucekkine, E. Furet, Z. Liu, J.-F.
Halet, C. Katan, T. B. Marder, Chem. Eur. J. 2014, 20, 13618–13635;
l) C. D. Entwistle, J. C. Collings, A. Steffen, L.-O. Palsson, A. Beeby, D.
Albesa-Jove, J. M. Burke, A. S. Batsanov, J. A. K. Howard, J. A. Mosely, S.-
[20] a) Y. Zhou, Y.-Z. Chen, J.-H. Cao, Q.-Z. Yang, L.-Z. Wu, C.-H. Tung, D.-Y.
Wu, Dyes Pigm. 2015, 112, 162–169; b) Z. Shen, H. Rçhr, K. Rurack, H.
Uno, M. Spieles, B. Schulz, G. Reck, N. Ono, Chem. Eur. J. 2004, 10,
4853–4871; c) Y.-H. Yu, A. B. Descalzo, Z. Shen, H. Rçhr, Q. Liu, Y.-W.
Wang, M. Spieles, Y.-Z. Li, K. Rurack, X.-Z. You, Chem. Asian J. 2006, 1,
176–187; d) L. Xie, Y. Chen, W. Wu, H. Guo, J. Zhao, X. Yu, Dyes Pigm.
2012, 92, 1361–1369; e) K. Rurack, M. Kollmannsberger, J. Daub, Angew.
Chem. Int. Ed. 2001, 40, 385–387; Angew. Chem. 2001, 113, 396–399.
[21] a) R. Englman, J. Jortner, Mol. Phys. 1970, 18, 145–164; b) M. Bixon, J.
Jortner, J. Cortes, H. Heitele, M. E. Michel-Beyerle, J. Phys. Chem. 1994,
98, 7289–7299.
[22] a) G.-L. Fu, H. Pan, Y.-H. Zhao, C.-H. Zhao, Org. Biomol. Chem. 2011, 9,
8141–8146; b) Y. Zhou, J. W. Kim, M. J. Kim, W.-J. Son, S. J. Han, H. N.
Kim, S. Han, Y. Kim, C. Lee, S.-J. Kim, D. H. Kim, J.-J. Kim, J. Yoon, Org.
Lett. 2010, 12, 1272–1275; c) W. C. Wu, H. C. Yeh, L. H. Chan, C. T. Chen,
Adv. Mater. 2002, 14, 1072–1075.
[23] a) Q. Bellier, S. Pꢁgaz, C. Aronica, B. L. Guennic, C. Andraud, O. Maury,
Org. Lett. 2011, 13, 22–25; b) G. Althoff, J. Ruiz, V. Rodriguez, G. Lopez,
J. Perez, C. Janiak, CrystEngComm 2006, 8, 662–665; c) L. Brammer, E. A.
Bruton, P. Sherwood, Cryst. Growth Des. 2001, 1, 277–290.
[24] D. Rohde, C.-J. Yan, L.-J. Wan, Langmuir 2006, 22, 4750–4757.
[25] a) L. Wang, Y. Shen, Q. Zhu, W. Xu, M. Yang, H. Zhou, J. Wu, Y. Tian, J.
Phys. Chem. C 2014, 118, 8531–8540; b) Y. Hong, J. W. Y. Lam, B. Z. Tang,
Chem. Commun. 2009, 4332–4353.
[26] G. Zhang, J. Lu, M. Sabat, C. L. Fraser, J. Am. Chem. Soc. 2010, 132,
2160–2162.
[27] M. A. Albota, C. Xu, W. W. Webb, Appl. Opt. 1998, 37, 7352–7356.
[28] M. Sheik-Bahae, A. A. Said, T. H. Wei, D. J. Hagan, E. W. Van Stryland, IEEE
J. Quantum Electron. 1990, 26, 760–769.
[29] M. Pawlicki, H. A. Collins, R. G. Denning, H. L. Anderson, Angew. Chem.
int. Ed. 2009, 48, 3244–3266; Angew. Chem. 2009, 121, 3292–3316.
[30] a) P.-A. Bouit, G. Wetzel, G. Berginc, B. Loiseaux, L. Toupet, P. Feneyrou,
Y. Bretonniꢄre, K. Kamada, O. Maury, C. Andraud, Chem. Mater. 2007, 19,
5325–5335; b) Q. Bellier, N. S. Makarov, P.-A. Bouit, S. Rigaut, K. Kamada,
P. Feneyrou, G. Berginc, O. Maury, J. W. Perry, C. Andraud, Phys. Chem.
Chem. Phys. 2012, 14, 15299–15307.
[31] a) A. D’Aleo, A. Felouat, F. Fages, Adv. Nat. Sci: Nanosci. Nanotech. 2015,
6, 015009; b) A. D’Aleo, A. Felouat, V. Heresanu, A. Ranguis, D. Chaudan-
son, A. Karapetyan, M. Giorgi, F. Fages, J. Mater. Chem. C 2014, 2, 5208–
5215.
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ÝÝ These are not the final page numbers!

Articles
[32] M. Ipuy, Y.-Y. Liao, E. Jeanneau, P. L. Baldeck, Y. Bretonniere, C. Andraud,
J. Mater. Chem. C 2016, 4, 766–779.
[34] CCDC 1426044 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre.
[33] a) S. Wanninger, V. Lorenz, A. Subhan, F. T. Edelmann, Chem. Soc. Rev.
2015, 44, 4986–5002; b) E. Kim, A. Felouat, E. Zaborova, J.-C. Ribierre,
J. W. Wu, S. Senatore, C. Matthews, P.-F. Lenne, C. Baffert, A. Karapetyan,
M. Giorgi, D. Jacquemin, M. Ponce-Vargas, B. L. Guennic, F. Fages, A.
D’Aleo, Org. Biomol. Chem. 2016, 14, 1311–1324; c) J. Samonina-Ko-
sicka, D. H. Weitzel, C. L. Hofmann, H. Hendargo, G. Hanna, M. W. Dew-
hirst, G. M. Palmer, C. L. Fraser, Macromol. Rapid Commun. 2015, 36,
694–699.
Manuscript received: February 19, 2016
Accepted Article published: March 18, 2016
Final Article published: && &&, 2016
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&
These are not the final page numbers! ÞÞ

ARTICLES
P.-H. Lanoꢀ, B. Mettra, Y. Y. Liao, N. Calin,
A. D’Alꢁo,* T. Namikawa, K. Kamada,
F. Fages, C. Monnereau,* C. Andraud*
Getting excited! The linear and nonlin-
ear optical properties of three two-
photon-absorbing, fluorescent boron di-
ketonate complexes are unraveled
through a combined spectroscopic and
computational study. All three com-
pounds display intense two-photon ab-
sorption (200–1200 GM) in the near-IR
range (l=700–1100 nm), along with
emission quantum yields that exceed
0.6 and that can reach unity in toluene.
&& – &&
Theoretical and Experimental Study
on Boron b-Diketonate Complexes
with Intense Two-Photon-Induced
Fluorescence in Solution and in the
Solid State
&
ChemPhysChem 2016, 17, 1 – 10
www.chemphyschem.org
10
ꢂ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!