Excited state intramolecular proton transfer in electron-rich and electron-poor derivatives of 10-hydroxybenzo[ h ]quinoline

Article abstract of DOI:10.1021/jp305459r

Eight previously inaccessible derivatives of 10-hydroxybenzo[h]quinoline were prepared via a straightforward strategy comprising formation of the benzo[h]quinoline skeleton followed by C-H acetoxylation at position 10. The occurrence of excited state intr

Full text of DOI:10.1021/jp305459r

Article
pubs.acs.org/JPCA
Excited State Intramolecular Proton Transfer in Electron-Rich and
Electron-Poor Derivatives of 10-Hydroxybenzo[h]quinoline
Joanna Piechowska,† Kirsi Huttunen,‡ Zbigniew Wrobel,† Helge Lemmetyinen,‡ Nikolai V. Tkachenko,*,‡
́
and Daniel T. Gryko*,†,§
†Institute of Chemistry of the Polish Academy of Sciences, Warsaw, Poland
‡Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland
§Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
S
* Supporting Information
ABSTRACT: Eight previously inaccessible derivatives of 10-hydroxybenzo-
[h]quinoline were prepared via a straightforward strategy comprising
formation of the benzo[h]quinoline skeleton followed by C−H acetoxylation
at position 10. The occurrence of excited state intramolecular proton transfer
(ESIPT) was detected in all cases since emission was observed only from the
excited keto-tautomer. Studies on derivatives bearing both electron-donating
and electron-withdrawing groups adjacent to the pyridine ring allowed us to
identify some design patterns giving rise to NIR emission and large Stokes
shifts. For a derivative of 10-hydroxybenzo[c]acridine, emission at 745 nm was observed, one of the lowest energy fluorescence
ever reported for ESIPT system. On the basis of time-resolved measurements, proton transfer was found to be extremely fast
with time constants in the range (0.08−0.45 ps).
with this modern synthetic tool could provide easy access to an
almost unlimited variety of structural analogues of 10-
hydroxybenzo[h]quinoline, which would then allow studies of
the structure−photophysical properties relationship. While
many heterocyclic systems have been reported to display
ESIPT, only a few reports have been devoted to the systematic
study of the optical properties of any of these scaffolds. Little is
known about the properties of the HBQ derivatives, especially
those bearing strongly electron-withdrawing and -donating
groups at various positions. The aim of this study was to apply
this new synthetic strategy to obtain a range of unique
derivatives of HBQ and to investigate their fundamental optical
properties. This approach would allow us to address the
tunability of chromophore absorption as well as proton transfer
emission, some of the most important issues of the ESIPT
system.
INTRODUCTION
■
Excited state inter- and intramolecular proton transfer
(ESIPT)1 has emerged as an interesting phenomenon that
can be utilized in the design of fluorescent sensors.2
Compounds displaying ESIPT include benzoxazoles,3 flavones,4
imidazoles,5 benzothiazoles,6 and anthraquinones.7 These
compounds possess a large Stokes shift and hence are suitable
for many applications such as laser dyes,8 fluorescence
recording,9 ultraviolet stabilizers,10 probes for solvation
dynamics,11 probes for biological environments,12 and, recently,
organic light emitting devices.13 10-Hydroxybenzo[h]quinoline
(HBQ) represents a fundamental heterocyclic systems in which
ESIPT occurs. Although this molecule has long been used as a
reagent in the preparation of optical filter agents in photo-
graphic emulsions, the fundamental studies of Chou and
colleagues identified ESIPT as the process responsible for the
strongly bathochromically shifted fluorescence of HBQ.14
Detailed photophysical and theoretical studies of HBQ showed
very fast and solvent-independent ESIPT,15 but broader studies
were hampered by considerable difficulties with the preparation
of its more elaborated derivatives.16 The recent discovery by
Sanford and co-workers of coordination-assisted acetoxylation
of derivatives and analogues of 2-phenylpyridine opened up
new possibilities.17 Acetate derivatives of 10-hydroxybenzo[h]-
quinoline prepared by this method can be easily hydrolyzed to
the corresponding phenol. It is noteworthy that, in 6-, 7-, and 8-
hydroxyquinolines, excited state proton transfer also occurs in
intra- or intermolecular fashion.18 These analogues of HBQ are
known to be photoacids.19 We envisioned that the combination
of the rich chemistry of quinolines (and their benzoanalogues)
EXPERIMENTAL SECTION
■
All chemicals were used as received unless otherwise noted.
Reagent grade solvents (CH2Cl2, hexanes) were distilled prior
1
to use. All reported H NMR and 13C NMR spectra were
collected using 600, 500, 400, or 200 MHz spectrometers.
Chemical shifts (δ ppm) were determined with TMS as the
internal reference; J values are given in Hz. The UV/vis
absorption spectra were recorded in CH2Cl2 or TFA. The
absorption wavelengths are reported in nm with the extinction
Received: June 4, 2012
Revised: August 15, 2012
Published: September 4, 2012
© 2012 American Chemical Society
9614
dx.doi.org/10.1021/jp305459r | J. Phys. Chem. A 2012, 116, 9614−9620

The Journal of Physical Chemistry A
Article
coefficient in M−1 cm−1 in parentheses. The melting points of
compounds were determined using a capillary type apparatus.
Chromatography was performed on silica (230−400 mesh) or
neutral alumina. Dry column vacuum chromatography
(DCVC)20 was performed on preparative thin-layer chroma-
tography alumina. The mass spectra were obtained via field
desorption MS (FD-MS), electrospray ionization (ESI-MS),
and electron impact MS (EI-MS). Compounds 1,21 9,22 15,23
and 1723 were prepared according to the literature procedures.
A spectrophotometer and a spectrofluorimeter were used to
acquire the absorption and emission spectra. Spectrophoto-
metric grade solvents were used without further purification.
Optical Studies. Steady-state absorption spectra were
measured by Shimadzu UV-3600 spectrophotometer. Cor-
rected emission spectra were acquired by Fluorolog 3
fluorimeter (SPEX Inc.), with excitation at 328−409 nm,
depending on the compound. Emission quantum yields of 2,
14, and 18 was determine using Rhodamine 6G as a standard.
The quantum yields of other compounds were too low to use a
highly emissive standard; therefore, 14 was used as the standard
for other compounds. Emission decays were measured using
two methods, femtosecond up-conversion and picosecond
time-correlated single-photon counting (TCSPC). The up-
conversion instrument has been described elsewhere.24 In brief,
the femtosecond pulses (ca. 50 fs) were generated by tunable
Ti:sapphire laser, which provided the excitation wavelengths in
the range 380−400 nm and the time resolution of
approximately 150 fs. The emission decays were measured at
three wavelengths when possible: at the expected emission
maximum of the enol form and close to the maximum and at
the red sides of the keto form emission band. The longest delay
time is limited by 1.2 ns for the up-conversion instrument.
Therefore, the samples with emission lifetime longer than a few
hundredths of picoseconds were also measured using TCSPC
instrumentation described elsewhere.24 In brief, the samples
were excited with a pulsed diode laser at 405 nm (LDH-P-C-
405B, PicoQuant GmbH), the emission detection range was
450−840 nm, and the time resolution was 60−70 ps.
Scheme 1. Preparation of 10-Hydroxybenzo[h]quinolines 2
and 7
RESULTS AND DISCUSSION
■
Design and Synthesis. Until recently, only a few
derivatives and analogues of 10-hydroxybenzo[h]quinoline
were known.16 We were interested in the effect of structural
modifications on photophysical properties. The design of our
small library was driven by two considerations: (a) introduction
of strongly electron-withdrawing and electron-donating sub-
stituents at this core and (b) expansion of the chromophore
itself. Along these lines, by combination of known methods for
the construction of quinolines, we synthesized eight analogues
of 10-hydroxybenzo[h]quinolines 2, 7, 8, 13, 14, 16, 18, and 22
(Schemes 1−5).21−31 Details of the synthesis are presented in
the Supporting Information.
emission spectra and the positions of the emission maxima
were strongly solvent dependent (Figure 2b). The absorption
spectra of 16 in THF and acetonitrile displayed no clear band,
which could be attributed to the lowest energy excited state
(Figure 1c); therefore, only a rough estimation of the maximum
positions were made for this compound, and consequently, the
calculated Stokes shift values are also estimations (Table 1).
The third compound with a clear solvent dependence on the
emission was 18 with the 7-nitro group, for which the emission
quantum yield was almost 20-fold lower in acetonitrile than in
toluene. However, the position of the emission maximum was
practically independent of the nature of the solvent.
Optical Studies. An examination of the spectral character-
istics of compounds 2, 7, 9, 12, 13, 15, 18, and 22 as compared
to those of the parent 10-hydroxybenzo[h]quinoline14,16a
(Table 1; Figures 1 and 2) revealed that ESIPT occurred in
all compounds. Steady-state fluorescence emission maxima
measurements showed emission by the keto-tautomer in the
spectral range 450−750 nm.
The positions of absorption and emission maxima were
virtually solvent independent with the exceptions of 7 and 16.
For 7, the absorption maximum shifted slightly to the blue in
more polar solvents. The intensities of the fluorescence
In his fundamental paper, Chou and co-workers stated that
the addition of electron-withdrawing substituents at the
pyridine ring of HBQ should result in a decrease of the lowest
9615
dx.doi.org/10.1021/jp305459r | J. Phys. Chem. A 2012, 116, 9614−9620

The Journal of Physical Chemistry A
Article
Scheme 2. Preparation of 10-Hydroxybenzo[h]quinolines
Scheme 4. Preparation of 10-Hydroxybenzo[h]quinoline 18
10, 13, and 14
Scheme 5. Preparation of Compound 22
Scheme 3. Preparation of 10-Hydroxybenzo[h]quinoline 16
methyl to cyano and SO2Ph group at position 4 of HBQ (14, 2,
13, and 10, respectively), we observed a small bathochromic
shift in absorption maxima (from 373 to 402 nm in CH2Cl2). In
agreement with the predictions of Chou, with the addition of
stronger electron-withdrawing substituents, the emission
maxima showed significant red-shifting from 599 nm for 4-
morpholino 14 to 720 nm for compounds 10 (4-tosyl) and 13
(4-cyano) (Table 1, Figure 1). Simultaneously, we detected
decreases in fluorescence quantum yields ranging 1.5−2.5% for
methyl derivative 2 and tertiary amine 14 to ∼0.05% for
derivatives 10 and 13, the compounds bearing electron-
withdrawing groups. This is also in line with observations of
Chou and co-workers and was attributed to energy gap law
predicting exponential increase of nonradiative relaxation rate
constant with a decrease of the emission energy gap.16a
unoccupied molecular orbital (LUMO), hence a decrease of the
energy gap of the keto-tautomer.16a This hypothesis, based on
DFT calculations, was never experimentally proved. Our results
are in agreement with this proposal. For derivatives substituted
at the pyridine ring, moving from tertiary amine through
9616
dx.doi.org/10.1021/jp305459r | J. Phys. Chem. A 2012, 116, 9614−9620

The Journal of Physical Chemistry A
Article
Surprisingly, the π-expanded derivative 7 lacked a bath-
ochromic shift of absorption. Its absorption maximum was
located around 395 nm (depending on the solvent). Its
emission was observed at 511 nm in CH2Cl2, a much shorter
wavelength value than any other HBQ derivative studied, and
this compound is characterized by the smallest Stokes shift in
this series. Probably steric flexibility of the styryl group is
responsible for rather different properties of this compound.
The 6-nitro 16 and 7-nitro 18 derivatives showed a minor
shift in fluorescence emission maxima to shorter wavelengths in
more polar solvents, but the emission quantum yield was clearly
solvent dependent. In more polar solvents, the fluorescence
emission intensity is weaker than in nonpolar solvents. This
effect is the most pronounced for 10-hydroxy-6-nitro-
benzoquinoline (16), one of the first derivatives with a
substituent at the middle ring ever studied (Figure 2c). The
addition of an electron withdrawing nitro group at position 7
(derivative 18), which belongs to dienone moiety and affects
mainly the highest occupied molecular orbital (HOMO) of
keto-tautomer, increases the energy gap for the keto-tautomer
(hypsochomic shift of the emission), as expected. The same
nitro group at position 6 (derivative 16) is expected to affect
mostly LUMO of the keto-tautomer, which should lead to
reduction of the energy gap and bathochromic emission shift.
However, the actual effect of nitro group at position 7 is a
hypsochromic emission shift as compared to nonsubstituted
benzo[h]quinoline and only minor bathochromic shift
compared to 16. Apparently, substitution at position 7 affects
both HOMO and LUMO with a net effect of a minor increase
of the energy gap of keto-tautomer.
Table 1. Optical Properties of Compounds 2, 7, 10, 13, 14,
16, 18, and 22
compound
λabs (nm)
λem (nm)
Stokes shift (cm−1
)
φF (%)
2
CH3CN
DCM
toluene
7
370
372
376
604
602
609
10500
10300
10200
1.43
1.73
1.38
CH3CN
DCM
toluene
10
390
394
399
470
511
447
4400
5800
2700
0.194
0.181
0.213
CH3CN
DCM
toluene
13
396
402
406
716
714
714
11300
10900
10600
0.059
0.067
0.077
CH3CN
DCM
toluene
14
402
408
411
712
714
717
11100
10500
10500
0.057
0.057
0.063
CH3CN
DCM
toluene
16
370
373
376
596
599
604
10200
10100
10000
2.23
2.50
1.96
a
CH3CN
DCM
toluene
18
420
582
580
587
6600
5800
5600
0.05
0.06
0.13
a
434
a
442
CH3CN
DCM
toluene
22
368
371
370
566
566
577
9500
9300
9700
0.16
0.58
3.05
Fluorescence quantum yields of products 2, 7, 10, 13, 14, 16,
18, and 22 were found to be generally very low (0.05−2.3) in
CH3CN (Table 1) and solvent independent, except com-
pounds 18 and 16 to a lesser degree. Fluorescence spectra were
obtained by exciting the molecules at 328−409 nm depending
on the compound. When compared to parent compound HBQ,
the Stokes shifts of many substituted derivatives were lower
(11 000 cm−1 for HBQ and 4400−9500 cm−1 for compounds 7,
16, 18, and 22). Both absorption and emission of π-expanded
compound 22 were bathochromically shifted versus HBQ,
which resulted in the lowest energy emission (∼745 nm) ever
reported for a ESIPT-capable system (Table 1).
CH3CN
DCM
toluene
458
461
464
740
745
745
8300
8300
8100
0.076
0.074
0.075
a
Approximate value for a maximum corresponding to the lowest
energy band.
According to expectations, the bathochromic shift of
absorption was visible when going from simple derivatives of
benzo[h]quinoline to its π-expanded analogues (Table 1;
Figures 1−2; λabs(13) = 411 nm (toluene); λabs(22) = 464 nm
(toluene)). However, the Stokes shift for π-expanded derivative
22 is smaller than that for derivative 13, which indicates that
enlarging conjugation of the pyridine moiety has an effect
similar to the attachment of an electron donating group.
(As indicated in Table 1, as a general trend, the polarity of
the solvent had little effect on the fluorescence quantum yield
(φF). As illustrated by compounds 2 and 14, the quantum
yields were relatively high and independent of solvent polarity.
Figure 1. (a) Absorption spectra of 2, 10, 13, 14, 18,and 22 in DCM. (b) Absorption spectra of 7 in four solvents. (c) Absorption spectra of 16 in
four solvents.
9617
dx.doi.org/10.1021/jp305459r | J. Phys. Chem. A 2012, 116, 9614−9620

The Journal of Physical Chemistry A
Article
Figure 2. (a) Emission spectra of 2, 13, 14, 18, 10, and 22 in DCM; multiplication factors are indicated in brackets. (b) Emission spectra of 7 in four
solvents (the sharp bands around 450 nm are due to Raman scattering by the solvents). (c) Emission spectra of 16 in four solvents.
Figure 3. Emission decays of 18 in acetonitrile monitored at three wavelengths, 500, 600, and 660 nm. Solid lines present global fit curves. Panel b
shows the same data as that in panel a but in an expanded time scale. Sample was excited at 390 nm.
Table 2. Decay Time Constants of Enol- (τenol) and Keto-Tautomers (τketo) Obtained from Emission Time-Resolved
Measurements, Emission Quantum Yields (φF), and Radiative Rate Constants (kr)
acetonitrile
THF
toluene
compound τenol (ps) τketo (ps) φf (%) kr (109 s−1
)
τenol (ps) τketo (ps) φf (%) kr (109 s−1
)
τenol (ps) τketo (ps) φf (%) kr (109 s−1
)
a
a
a
2
0.31
0.14
0.21
0.36
0.33
627
36
1.4
0.022
0.017
0.019
0.025
0.02
0.30
0.12
0.13
0.39
0.49
654
47
1.4
0.022
0.015
0.014
0.024
0.024
0.45
0.19
0.24
0.45
0.35
690
56
1.4
0.02
10
13
14
18
0.06
0.06
2.2
0.07
0.05
2.1
0.08
0.06
2.0
0.014
0.013
0.024
0.021
32
35
45
a
a
a
a
863
82
876
993
818
a
0.16
2.4
1490
3.1
a
Measured by TCSPC instrument.
For 18, however, the emission yield was highest in nonpolar
toluene, 3.05%, but fell to 0.16% in more polar acetonitrile.)
We considered that low emission yield could arise from fast
nonradiative relaxation. To verify this hypothesis, we measured
emission decays for 2, 10, 13, 14, and 18 in acetonitrile, THF,
and toluene. The primary excited state for the compounds
should be the singlet excited state of the enol-tautomer. One
can expect to observe the fluorescence of the enol-tautomer at
the red edge of the absorption band since the Stokes shift for
the enol-tautomer should be relatively small. Therefore, we
measured the fluorescence emission decays at three wave-
lengths: close to the red edge of the absorption band
representing the enol-tautomer, close to the emission maximum
of the keto-tautomer, and at the red edge of the keto emission
band. As an example, the emission decays are shown for 18 in
acetonitrile in Figure 3. The decays at all three wavelengths
were fitted simultaneously using a three-exponential model,
which gave lifetimes of 0.33, 14, and 82 ps. The fast component
dominates the decay at 500 nm, which is expected to be the
decay of the singlet excited state of the enol-tautomer. At 600
and 660 nm, the decay is almost monoexponential with time
constant of 82 ps, which is the lifetime of the keto-tautomer,
and the 0.33 ps component is seen as formation of the
emission. This observation has a straightforward interpretation:
the singlet excited enol-tautomer has a very short lifetime and
undergoes rapid conversion to the keto-tautomer. Thus, the
time constant for the proton transfer in this case is 0.33 ps, and
the lifetime of the excited state of keto- tautomer is 82 ps. An
intermediate component, with lifetime of 14 ps, is relatively
weak at all wavelengths and presumably originates from the
solvent relaxation dynamics.32,33 Similar emission decays were
obtained for all compounds, and the lifetimes are summarized
in Table 2.
In all cases, the proton transfer was found to be extremely
fast with time constants in the range 0.08−0.45 ps. The proton
transfer leads to the formation of the singlet excited keto-
tautomer. The time constant of the relaxation of the excited
state of the keto tautomer was much slower, with the most
9618
dx.doi.org/10.1021/jp305459r | J. Phys. Chem. A 2012, 116, 9614−9620

The Journal of Physical Chemistry A
Article
rapid being 32 ps for 13 in acetonitrile and the slowest at 1.5 ns
for 18 in toluene. The longest delay time available from our up-
conversion instrument was 1 ns; therefore, to obtain accurate
lifetimes in time scales longer than a few hundredths of a
picosecond, the TCSPC instrument was used. An example of
the emission decays measured by TCSPC instrument is
presented in Figure 4 and shows the measurements of 18 in
CONCLUSIONS
■
Using novel compounds, we systematically studied the effect of
both electron-donating and electron-withdrawing substituents
on the optical properties of derivatives and analogues of 10-
hydroxybenzo[h]quinoline. Insertion of electron-withdrawing
groups at the pyridine-ring of HBQ resulted in extending the
fluorescence emission to the NIR region and affording large
Stokes shifts. Conversely, a strongly electron-donating amino
group influenced neither the emission nor the absorption
maxima. Derivatives bearing electron-donating groups dis-
played higher fluorescence quantum yields. The strongly
electron-withdrawing nitro group had various effects on
absorption maxima depending on the actual site of insertion.
We proved that, as far as the radiative rate constants are
concerned, similarity in chromophore scaffold is a more
important factor than large structural variations at its periphery.
These results are not only of theoretical significance in that they
provide new insight into factors influencing the ESIPT
phenomenon but they may also open doors to practical
applications in biological imaging.
Figure 4. Emission decays of 18 at 600 nm in the indicated solvents as
measured by TCSPC instrumentation.
ASSOCIATED CONTENT
■
S
* Supporting Information
Syntheses and complete experimental section. This material is
available free of charge via the Internet at http://pubs.acs.org.
four solvents. Compound 18 was the only candidate with
strong solvent dependency for the emission lifetime. The wide
variations in decay rates with respect to solvent polarity were
expected, considering that the emission intensities and the
quantum yields were greater in more nonpolar solvents.
Emission quantum yield divided by the lifetime of the
emissive state gives the radiative rate constant. Notably, for all
measured samples, the radiative rate constants for the keto-
tautomer are in the range (1.3−2.4) × 107 s−1, despite rather
large structural and photophysical differences between
compounds. Apparently, the similarity in chromophore back-
bone is the main determinant of the radiative rate constants,
and this fact accounts for the consistency of the results obtained
by different methods. The large variation in emission lifetimes
and thus emission quantum yields is due to the large difference
in nonradiative decay rate constants for this series of
compounds. Previously, a good correlation between the
nonradiative rate constant and energy gap of keto tautomer
was reported by Chou and co-workers.16a A similar trend can
be seen for compounds 2, 10, 13, and 14. Derivatives 2 and 14
have a larger energy gap for the keto-tautomer and a longer
emission lifetime than derivatives 10 and 13. However,
behavior of derivative 18 is more complex. In toluene, the
compound has the longest emission lifetime compared to
compounds 2, 10, 13, and 14, which is in agreement with the
fact that derivative 18 has the highest energy gap, but the
lifetime decreases sharply with an increase in solvent polarity,
whereas the energy gap remains almost independent of the
solvent. This type of behavior is indicative for an opening of
another relaxation channel in polar solvents. One of the
processes sensitive to the solvent polarity is intramolecular
charge transfer, which may take place considering strong
electron withdrawing character of the nitro group and highly
uneven electron density distribution in core HBQ structure, but
at present, we have no firm experimental proof for this
hypothesis.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: dtgryko@icho.edu.pl (D.T.G.); nikolai.tkachenko@
tut.fl (N.V.T.).
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was funded by the Foundation for Polish Science
(TEAM-2009-4/3).
REFERENCES
■
(1) (a) Herbich, J.; Dobkowski, J.; Thummel, R. P.; Hegde, V.;
Waluk, J. J. Phys. Chem. A 1997, 101, 5839−5845. (b) Kyrychenko, A.;
Herbich, J.; Izydorzak, M.; Gil, M.; Dobkowski, J.; Wu, F. Y.;
Thummel, R. P.; Waluk, J. Isr. J. Chem. 1999, 39, 309−318.
(c) Kyrychenko, A.; Herbich, J.; Izydorzak, M.; Wu, F.; Thummel,
R. P.; Waluk, J. J. Am. Chem. Soc. 1999, 121, 11179−11188.
(d) Herbich, J.; Hung, C. Y.; Thummel, R. P.; Waluk, J. J. Am.
Chem. Soc. 1996, 118, 3508−3518. (e) Dobkowski, J.; Herbich, J.;
Galievsky, V.; Thummel, R. P.; Wu, F. Y.; Waluk, J. Ber. Bunsenges.
Phys. Chem. 1998, 102, 469−475. (f) Kyrychenko, A.; Herbich, J.; Wu,
F.; Thummel, R. P.; Waluk, J. J. Am. Chem. Soc. 2000, 122, 2818−
2827. (g) Herbich, J.; Waluk, J.; Thummel, R. P.; Hung, C. Y. J.
Photochem. Photobiol., A 1994, 80, 157−160. (h) Herbich, J.; Kijak, M.;
́
Zielinska, A.; Thummel, R. P.; Waluk, J. J. Phys. Chem. A 2002, 106,
2158−2163. (i) Waluk, J. Acc. Chem. Res. 2003, 36, 832−838.
(j) Kwon, J. E.; Park, S. Y. Adv. Mater. 2011, 23, 3615−3642. (k) Fang,
C.; Frontiera, N. N.; Tran, R.; Mathies, R. A. Nature 2009, 462, 200−
204.
(2) (a) Kim, J. S.; Quang, D. T. Chem. Rev. 2007, 107, 3780−3799.
(b) Wang, B.; Anslyn, E. V. Chemosensors: Principles, Strategies, and
Applications; Wiley: New York, 2011; pp 253−273; (c) Roshal, A. D.;
Grigorovich, A. V.; Doroshenko, A. O.; Pivovarenko, V. G. J. Phys.
Chem. A 1998, 102, 5907−5914. (d) Landge, S. M.; Tkatchouk, K.;
Benitez, D.; Lanfranchi, D. A.; Elhabiri, M.; Goddard, W. A., III;
Aprahamian, I. J. Am. Chem. Soc. 2011, 133, 9812−9823.
9619
dx.doi.org/10.1021/jp305459r | J. Phys. Chem. A 2012, 116, 9614−9620

The Journal of Physical Chemistry A
Article
(e) Svechkarev, D. A.; Karpushina, G. V.; Lukatskaya, L. L.;
Doroshenko, A. O. Cent. Eur. J. Chem. 2008, 6, 443−449.
́ ́
(3) (a) Mordzinski, A.; Grabowska, A.; Kuhnle, W.; Krowczynski, A.
H. Anal. Chem. 2003, 75, 413−419. (c) Gryko, D. T.; Piechowska, J.;
Gałęzowski, M. J. Org. Chem. 2010, 75, 1297−1300.
(17) (a) Dick, A. R.; Hull, K. L.; Sanford, M. S. J. Am. Chem. Soc.
2004, 126, 2300−2301. (b) Desai, L. V.; Stowers, K. J.; Sanford, M. S.
J. Am. Chem. Soc. 2008, 130, 13285−13293. (c) Stowers, K. J.; Sanford,
M. S. Org. Lett. 2009, 11, 4584−4587. (d) Dick, A. R.; Kampf, J. W.;
Sanford, M. S. J. Am. Chem. Soc. 2005, 127, 12790−12791. (e) Fu, Y.;
Li, Z.; Liang, S.; Guo, Q.-X.; Liu, L. Organometallics 2008, 27, 373−
3742. (f) Racowski, J. M.; Dick, A. R.; Sanford, M. S. J. Am. Chem. Soc.
2009, 131, 10974−10983. (g) Lyons, T. W.; Sanford, M. S. Chem. Rev.
2010, 110, 1147−1169. (h) Powers, D. C.; Ritter, T. Nat. Chem. 2009,
1, 302−309. (i) Bian, Y.-J.; Xiang, C.-B.; Chen, Z.-M.; Huang, Z.-Z.
Synlett 2011, 2407−2409.
Chem. Phys. Lett. 1983, 101, 291−296. (b) Frey, W.; Laermer, F.;
Elsaesser, T. J. Phys. Chem. 1991, 95, 10391−10395. (c) Das, K.;
Sarkar, N.; Majumda, D.; Bhattacharyya, K. Chem. Phys. Lett. 1992,
198, 443−448. (d) Fores, M.; Duran, M.; Sola, M.; Adamowicz, L. J.
Phys. Chem. A 1999, 103, 4413−4420. (e) Wang, H.; Zhang, H.; Abou-
Zied, O. K.; Yu, C.; Romesberg, F. E.; Glasbeek, M. Chem. Phys. Lett.
2003, 367, 599−608. (f) Rini, M.; Dreyer, J.; Nibbering, E. T. J.;
Elsaesser, T. Chem. Phys. Lett. 2003, 374, 13−19.
(4) (a) McMorrow, D.; Kasha, M. J. Phys. Chem. 1984, 88, 2235−
2243. (b) Strandjord, A. J. G.; Smith, D. E.; Barbara, P. F. J. Phys.
Chem. 1985, 89, 2362−2366. (c) Chou, P.-T.; Chen, Y.-C.; Yu, W.-S.;
Chen, Y.-M. Chem. Phys. Lett. 2001, 340, 89−97.
(5) (a) Druzhinin, S. I.; Rodchenkov, G. M.; Uzhinov, B. M. Chem.
Phys. 1988, 128, 383−394. (b) LeGourrierec, D.; Kharlanov, V. A.;
Brown, R. G.; Rettig, W. J. Photochem. Photobiol., A 2000, 130, 101−
111. (c) Chen, K.-Y.; Cheng, Y.-M.; Lai, C.-H.; Hsu, C.-C.; Ho, M.-L.;
Lee, G.-H.; Chou, P.-T. J. Am. Chem. Soc. 2007, 129, 4534−4535.
(d) Kanda, T.; Momotake, A.; Shinohara, Y.; Sato, T.; Nishimura, Y.;
Arai, T. Bull. Chem. Soc. Jpn. 2009, 82, 118−120. (e) Kaczmarek, Ł.;
Balicki, R.; Lipkowski, J.; Borowicz, P.; Grabowska, A. J. Chem. Soc.,
Perkin Trans. 2 1994, 1603−1610. (f) Bulska, H.; Grabowska, A.;
Grabowski, Z. R. J. Lumin. 1986, 35, 189−197. (g) Skonieczny, K.;
Ciuciu, A. I.; Nichols, E.; Hugues, V.; Blanchard-Desce, M.; Flamigni,
L.; Gryko, D. T. J. Mater. Chem. 2012, 22, 20649−20664. (h) Park, S.;
Kwon, J. E.; Park, S. Y. Phys. Chem. Chem. Phys. 2012, 14, 8878−8884.
(6) (a) Ding, K.; Courtney, S. J.; Strandjord, A. J.; Flom, S.; Friedrich,
D.; Barbara, P. F. J. Phys. Chem. 1983, 87, 1184−1188. (b) Grando, S.
R.; Pessoa, C. M.; Gallas, M. R.; Costa, T. M. H.; Rodembusch, F. S.;
Benvenutti, E. V. Langmuir 2009, 25, 13219−13223. (c) Yao, D.;
Zhao, S.; Guo, J.; Zhang, Z.; Zhang, H.; Liu, Y.; Wang, Y. J. Mater.
Chem. 2011, 21, 3568−3570.
(18) (a) Bardez, A. Isr. J. Chem. 1999, 39, 319−332. (b) Arnaut, L.
G.; Formosinho, S. J. J. Photochem. Photobiol., A 1993, 75, 1−20.
(c) Bach, A.; Tanner, C.; Manca, C.; Frey, H.-M.; Leutwyler, S. J.
Chem. Phys. 2003, 119, 5933−5942. (d) Lahmani, F.; Douhal, A.;
Breheret, E.; Zehnacker-Rentien, A. Chem. Phys. Lett. 1994, 220, 235−
242.
(19) (a) Bardez, E.; Chatelain, A.; Larrey, B.; Valeur, B. J. Phys. Chem.
1994, 98, 2357−2366. (b) Solntsev, K. M.; Clower, C. E.; Tolbert, L.
M.; Huppert, D. J. Am. Chem. Soc. 2005, 127, 8534−8544.
(20) Pedersen, D. S.; Rosenbohm, C. Synthesis 2001, 2431−2434.
(21) Campbell, K. N.; Schaffner, I. J. J. Am. Chem. Soc. 1945, 67, 86−
89.
́
(22) Wrobel, Z. Eur. J. Org. Chem. 2000, 521−525.
(23) Barltrop, J. A.; MacPhee, K. E. J. Chem. Soc. 1952, 638−642.
(24) Niemi, M.; Tkachenko, N. V.; Efimov, A.; Lehtivuori, H.;
Ohkubo, K.; Fukuzumi, S.; Lemmetyinen, H. J. Phys. Chem. A 2008,
112, 6884−6892.
(25) Piechowska, J.; Gryko, D. T. J. Org. Chem. 2011, 76, 10220−
10228.
(26) Eynde, J. J. V.; Pascal, L.; Haverbeke, Y. V.; Dubois, P. Synth.
Commun. 2001, 31, 3167−3173.
(27) (a) Tipson, R. S. J. Am. Chem. Soc. 1945, 67, 507−511.
(b) Stevens, A. C.; Frutos, R.; Harvey, D. F.; Brian, A. A. Bioconjugate
Chem. 1993, 4, 19−24.
(28) Beverina, L.; Abbotto, A.; Landenna, M.; Cerminara, M.;
Tubino, R.; Meinardi, F.; Bradamante, S.; Pagani, G. A. Org. Lett. 2005,
7, 4257−4260.
(29) Mąkosza, M. Synthesis 2011, 2341−2356.
(30) Valeur, B. Molecular Fluorescence Principles and Applications;
Wiley-VCH: Berlin, Germany, 2002.
(7) (a) Jung, H. S.; Kim, H. J.; Vicens, J.; Kim, J. S. Tetrahedron Lett.
2009, 50, 983−987. (b) Van Benthem, M. H.; Gillispie, G. D. J. Phys.
Chem. 1984, 88, 2954−2960. (c) Smith, T. P.; Zaklika, K. A.; Thakur,
K.; Barbara, P. F. J. Am. Chem. Soc. 1991, 113, 4035−4036.
(d) Schmidtke, S. J.; Underwood, D. F.; Blank, D. A. J. Am. Chem.
Soc. 2004, 126, 8620−8621.
́
(8) (a) Acuna, A. V.; Amat-Guerri, F.; Catalan, J.; Costella, A.;
Figuera, J.; Munoz, J. M. Chem. Phys. Lett. 1986, 132, 567−569.
(b) Sakai, K. I.; Tsuzuki, T.; Itoh, Y.; Ichikawa, M.; Taniguchi, Y. Appl.
Phys. Lett. 2005, 86, 081103.
́
(31) Wrobel, Z. Synlett 2004, 1929−1932.
(32) Domcke, W.; Sobolewski, A. L.; Woywod, C. Chem. Phys. Lett.
1993, 203, 220−226.
(9) (a) Kim, S.; Park, S. Y. Adv. Mater. 2003, 15, 1341−1344.
(b) Kim, S.; Park, S. Y.; Tashida, I.; Kawai, H.; Nagamura, T. J. Phys.
Chem. B 2002, 106, 9291−9294.
(33) (a) Castner, E. W., Jr.; Maroncelli, M.; Fleming, G. R. J. Chem.
Phys. 1987, 86, 1090−1097. (b) Horng, M. L.; Gardecki, J. A.;
Papazyan, A.; Maroncelli, M. J. Phys. Chem. 1995, 99, 17311−17337.
́
(10) Catalan, J.; del Valle, J. C.; Claramunt, R. M.; Sanz, D.; Dotor, J.
J. Lumin. 1996, 68, 165−170.
(11) Parsapour, F.; Kelley, D. F. J. Phys. Chem. 1996, 100, 2791−
2798.
(12) Sytnik, A.; Kasha, M. Proc. Natl. Acad. Sci. U.S.A. 1994, 91,
8627−8630.
(13) (a) Kim, S.; Seo, J.; Jung, H. K.; Kim, J. J.; Park, S. Y. Adv. Mater.
2005, 17, 2077−2082. (b) Park, S.; Kwon, J. E.; Kim, S. H.; Seo, J.;
Chung, K.; Park, S.-Y.; Jang, D.-J.; Medina, B. M.; Gierschner, J.; Park,
S.-Y. J. Am. Chem. Soc. 2009, 131, 14043−14049.
(14) (a) Martinez, M. L.; Cooper, W. C.; Chou, P.-T. Chem. Phys.
Lett. 1992, 193, 151−154. (b) Chou, P.-T.; Chen, Y.-C.; Yu, W.-S.;
Chou, Y.-H.; Wei, C.-Y.; Cheng, Y.-M. J. Phys. Chem. A 2001, 105,
1731−1740.
(15) (a) Chou, P.-T.; Wei, C. Y. J. Phys. Chem. 1996, 100, 17059−
17066. (b) Takeuchi, S.; Tahara, T. J. Phys. Chem. A 2005, 109,
10199−10207. (c) Paul, B. K.; Guchhait, N. J. Lumin. 2011, 131,
1918−1926. (d) Higashi, M.; Saito, S. J. Phys. Chem. Lett. 2011, 2,
2366−2371.
(16) (a) Chen, K.-Y.; Hsieh, C.-C.; Cheng, Y.-M.; Lai, C.-H.; Chou,
P.-T. Chem. Commun. 2006, 4395−4397. (b) Matsumiya, H.; Hoshino,
9620
dx.doi.org/10.1021/jp305459r | J. Phys. Chem. A 2012, 116, 9614−9620