N-(2-(N′,N′-diethylamino)ethyl)perylene-3,4-dicarboximide and its quaternized derivatives as fluorescence probes of acid, temperature, and solvent polarity

Article abstract of DOI:10.1007/s10895-010-0708-z

In this manuscript, we report the fluorescence properties of N-(2-(N′,N′-diethylamino)ethyl)perylene-3,4-dicarboximide (1) and its quaternized derivative N-(2-(N′,N′- diethyl-N′- methylammonium)ethyl)perylene-3,4-dicarboximide tosylate (2) in organic solv

Full text of DOI:10.1007/s10895-010-0708-z

J Fluoresc (2011) 21:213–222
DOI 10.1007/s10895-010-0708-z
ORIGINAL PAPER
N-(2-(N’,N’-Diethylamino)ethyl)perylene-3,4-dicarboximide
and its Quaternized Derivatives as Fluorescence Probes
of Acid, Temperature, and Solvent Polarity
Liming Huang & Suk-Wah Tam-Chang
Received: 20 October 2009 /Accepted: 11 August 2010 /Published online: 25 August 2010
#
Springer Science+Business Media, LLC 2010
Abstract In this manuscript, we report the fluorescence
properties of N-(2-(N’,N’-diethylamino)ethyl)perylene-3,4-
dicarboximide (1) and its quaternized derivative N-(2-(N’,N’-
diethyl-N’-methylammonium)ethyl)perylene-3,4-dicarboxi-
mide tosylate (2) in organic solvents. The effects of carboxylic
acids and amines on the fluorescence properties of these
compounds were investigated. In addition, we studied the
aggregation and fluorescence properties of (2) and its
9-bromo-substituted derivative (3) in aqueous solution. The
fluorescent properties of these compounds change dramatical-
ly with the extent of aggregation, thus allowing these
compounds to be used as fluorescent probes for changes in
temperature and solvent polarity. For instance, the fluores-
cence emission intensity of 3 increases by about 28 times as
the temperature of the solution increases from 10°C to 85°C.
The fluorescent intensities of 2 and 3 in methanol are higher
than that in water by about 8 and 25 times, respectively.
these compounds have potential applications in bioassays
[9–16], light harvesting systems, and photovoltaic devices
[17–27], the structural effects on the fluorescence properties
of perylene-3,4-dicarboximides, particularly in aqueous
solution, remain largely unexplored. A deeper understanding
of the structural effects on electronic transition and fluores-
cence properties of perylene-3,4-dicarboximides is important
for developing applications and future design of fluoro-
phores with desired properties.
We reported recently the direction-dependent electronic
transition and fluorescence properties of N-(2-(N’,N’-dieth-
ylamino)ethyl)perylene-3,4-dicarboximide 1 and its quater-
nized derivative 2 in the crystal phase [28, 29]. In this
manuscript, we report the fluorescence properties of these
compounds and the 9-bromo-substituted derivative 3 in
organic solvents and aqueous solution. The structures of
compounds 1–3 are shown in Fig. 1.
We are interested in investigating the fluorescence proper-
ties of these compounds in solution for several reasons. Firstly,
the flexible (N,N-diethylamino)ethyl group of compound 1
not only imparts solubility in common organic solvents but
also present an electron rich amino group for quenching
fluorescence emission of the perylene-3,4-dicarboximide ring
by photoinduced electron transfer (Fig. 2). Protonation of the
amino nitrogen lone-pair electrons will turn off this quench-
ing mechanism, thereby allowing the use of 1 as fluorescence
probe for detection of acids. Secondly, compounds that
fluoresce in aqueous solution are generally useful in medical
diagnostics, studies in life sciences, biomedical and biological
research, and environmental analysis [30–35]. The quater-
nized derivative 2 has higher solubility than 1 in polar
solvents and aqueous solution and is potentially useful in a
broader range of applications. Water-soluble fluorophores
with properties that vary with changes in environment are
particularly important for sensing applications [36, 37]. In this
.
.
Keywords Perylene monoimide Fluorescence probe
.
Photoinduced electron transfer Aggregates
Introduction
Fluorescent compounds have important applications in
clinical diagnostics, biomedical research, studies in life
sciences, and as luminescent materials in optical devices [1].
Although there are reports of the photophysical properties of
perylene-3,4-dicarboximides (or perylene monoimide) in
organic solvents [2–4] and polymers [5–8] suggesting that
:
L. Huang S.-W. Tam-Chang (*)
Department of Chemistry, University of Nevada,
Reno, NV, USA
e-mail: tchang@unr.edu

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J Fluoresc (2011) 21:213–222
O
O
N
O
SO3
ly, the emission of 2 is not quenched by intramolecular PET
and does not vary with the acid concentration in solution.
The pKa values of the N-(2-(N’,N’-diethylamino)ethyl)
perylene-3,4-dicarboximide and perylene-3,4:9,10-bis
(dicarboximide) in methanol or ethanol and water mixtures
were found to be in the range of 9.5–9.8 [35], which are
similar to the value of 9.9 determined for the pKa of the
monoprotonated species of 1-amino-2-diethylaminoethane
and not significantly influenced by the aromatic rings. Base
on these values, the pKa value of 1 is estimated to be in the
same range (9.5–9.8).
Using fluorescein (quantum yield of 1.0 in MeOH with
0.01 M KOH) as reference standard [40], the fluorescence
quantum yield of 2 in MeOH was determined to be 0.50.
The quantum yield of 1 in DCM is only 0.06 presumably
due to quenching by intramolecular PET. The quantum
yield of 1 in MeOH/DCM (v:v=50:50) is 0.12, slightly
higher than that in DCM, presumably because of the
presence of some protonated form in MeOH/DCM (v:v=
50:50). Fluorescence emission of the protonated form is not
quenched by intramolecular PET.
N
O
N
Me
N
X
2: X=H
3: X=Br
Me
1
Fig. 1 Structures of perylene-3,4-dicarboximides 1–3
paper, the effects of temperature and solvent polarity on the
fluorescence properties of 2 in aqueous solution are pre-
sented. Thirdly, substituents on the perylene-3,4-dicarboxi-
mide ring may modulate the aggregation, and hence
fluorescence properties of ionic perylene-3,4-dicarboximides
in aqueous solution. We demonstrate such effect using the
ionic 9-bromoperylene-3,4-dicarboximide derivative 3.
Results and discussion
Effects of organic acids and bases on the UV-vis absorption
and fluorescence properties of 1 and 2 in organic solvents
2-(N,N-Diethylamino)ethylperylene-3,4-dicarboximide (1)
is soluble in organic solvents such as chloroform (CHCl3)
and dichloromethane (DCM), but less soluble in methanol
(MeOH). The ionic derivative 2 has higher solubilities in
MeOH than in CHCl3. To allow comparison of the optical
properties of 1 and 2 in organic solvents, UV-vis and
fluorescence studies were performed in a mixture of DCM/
MeOH. In this solvent mixture, compounds 1 and 2 have
similar electronic transition properties which are not
affected significantly by the addition of organic acids such
as 5 vol% of formic acid (HCOOH) or acetic acid
(CH3COOH) (Fig. 3). In the presence of an organic base
such as 5 vol% of piperidine, a small blue shift (about
10 nm) in the absorption band of 1 is resulted.
Both 1 and 2 exhibit fluorescence emission (λmax of
emission at about 560 nm) upon excitation at 491–495 nm;
a Stokes shift of about 70 nm. As shown in Fig. 4, there is
no significant change in fluorescence emission of 2 in the
presence of as much as 5 vol % of CH3COOH or HCOOH.
At similar concentrations (1.0×10−7 M), the emission
intensity of 1 is substantially lower than that of 2 and is
greatly enhanced in the presence of CH3COOH (Fig. 5).
The enhancement can be observed in the presence of as
little as 5 μM of CH3COOH. Presumably, the fluorescence
emission of 1 is quenched by a photoinduced electron
transfer (PET) process [1, 30–35, 38, 39] in the presence of
lone-pair electrons of the tertiary amino group of 1.
Removal of the lone-pair electrons of the amino group of
1 by protonation with acids prevents the quenching of
fluorescence emission by PET. The results show that 1
serves as fluorescence probe of acids in organic solvents.
Amino nitrogen lone-pair is not available in 2, consequent-
Results of the time-resolved fluorescence lifetime studies of
the effect of acids are consistent with the results of the steady
state experiments. The lifetime of a 1.0×10−6 M solution of 2
in MeOH/DCM (v:v=50:50) is 5.3 ns and it does not change
in the presence CH3COOH (1–5 vol %) in MeOH/DCM. In
contrast, the lifetime of 1 changes in the presence of acid.
Lifetime studies of 1 in MeOH/DCM (v:v=50:50), indicated
the presence of a species (20%) with a lifetime of 5.0 ns, and
a short-lived species (80%) with a lifetime of about 1.0 ns.
Presumably, 1 has a short lifetime of about 1 ns because of
quenching by the nitrogen lone-pair of the amino side chain,
and some protonated form of 1 is present in MeOH/DCM
resulting in the longer lifetime of 5.0 ns observed. After the
addition of CH3COOH (1–5 vol %), the amino group of 1 is
protonated, resulting in a species of lifetime of 5.3 ns only.
Although the fluorescence emission of 2 is not quenched
by intramolecular PET process, it can be quenched by
intermolecular PET. Quenching of 2 by intermolecular PET
was studied using piperidine (an alicyclic amine) and N-
Fig. 2 Diagram illustrating the quenching of fluorescence emission of
1 by photoinduced electron transfer (PET) from the non-bonding
orbital of amine nitrogen

J Fluoresc (2011) 21:213–222
215
Fig. 3 (a) Absorption spectra of
1 in (Δ) MeOH/DCM (v/v=50/
50) and (o) MeOH/DCM/
HCOOH (v/v/v=47.5/47.5/5),
and (x) MeOH/DCM/piperidine
(v/v/v=47.5/47.5/5). (b) Ab-
sorption spectra of 2 in (Δ)
MeOH/DCM (v/v=50/50) and
(o) MeOH/DCM/HCOOH (v/v/
v=47.5/47.5/5), and (x) MeOH/
DCM/piperidine (v/v/v=47.5/
47.5/5)
ethylaniline (an aromatic amine). As shown in Fig. 6, the
addition of piperidine (e.g., 1 vol%, ~0.1 M) to a solution
of 2 (e.g., 1×10−7 M) in methanol has no significant effect
on the wavelengths of emission, however, it lowers the
fluorescence intensity of 2. The quenching effect is weak
and requires a high molar ratio of piperidine to cause a
significant decrease in fluorescence intensity. The quench-
ing constants (KD) determined from the slopes of the linear
Stern-Volmer plots (Fig. 7) are 1.3, 1.8, and 2.3 M−1 at 25°
C, 35°C, and 45°C, respectively. The increase in quenching
constant with temperature suggests that the decrease in
fluorescence is caused by collisional quenching effect [1] of
piperidine. Diffusion rate, and thus, quenching by collision
increase as temperature increases.
required for 50% quenching. An upward curvature is
observed for the Stern-Volmer plot (Fig. 8, left). The
dependence of F0/F on the concentration of N-ethylaniline
is second order in the concentration of N-ethylaniline. This
suggests that the quenching of 2 occurs by both collisional
quenching and a static mechanism [1]. The values of
collision quenching constant (KD) and static quenching
constant (KS) were determined from the plot of ((Fo-F)/F[N-
ethylaniline]) versus [N-ethylaniline]. According to Eq. 1,
the slope of the linear plot equals KDKS and the intercept
equals (KD+KS) [1]. From the slope and intercept of the
plot (Fig. 8, right), the values of KD and KS at 35°C were
calculated to be 4.5 M−1 and 97 M−1, respectively.
N-ethylaniline is a more effective quencher than piper-
idine. Quenching of emission of 2 (1×10−7 M) at 35°C
occurs in the presence of N-ethylaniline at concentrations as
low as 0.5 mM, and only about 0.01 M of N-ethylaniline is
ðFo ꢀ FÞ=F½N ꢀ ethylanilineꢁ ¼ KDKS½N ꢀ ethylanilineꢁ þ ðKD þ KSÞ
ð1Þ
Effects of solvent polarity and temperature on UV-vis
absorption and fluorescence properties of 2 and 3
in MeOH and aqueous solution
The ionic derivatives 2 and 3 have higher solubilities in
MeOH than in CHCl3. They can also be dissolved in water to
give dilute solutions at room temperature. Compounds 2 (1.0×
10−5 M) and 3 (1.0×10−5 M) in MeOH have similar λmax of
absorption. At similar concentrations, the λmax values of these
compounds in water are blue-shifted compared to that in
MeOH. The molar absorptivities of these compounds in water
are lower than those in MeOH (see λmax values and molar
absorptivities provided in the experimental section.)
The aggregation of 2 and 3 in water was investigated
using UV-vis spectroscopy. Upon varying the concentration
of 2 over the range of 1.0×10−7 M to 1.0×10−3 M, a blue
shift in λmax from 504 nm to 482 nm in the visible spectra
was observed due to aggregation of 2 (Fig. 9a). Similar
shift was observed for 3 (Fig. 9b). At a low concentration
(1.0×10−7 M), the λmax of 3 is at 487 nm. It shifts gradually
Fig. 4 Fluorescence spectra of 2 (1.0×10−7 M) (o) in MeOH/DCM
(v/v=50/50), (x) in MeOH/DCM/CH3COOH (v/v/v=47.5/47.5/5),
and (Δ) in MeOH/DCM/HCOOH (v/v/v=47.5/47.5/5). The spectra
in the presence of CH3COOH or HCOOH overlapped with the spectra
in the absence of acids

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Fig. 6 Effect of piperidine on the fluorescence properties of 2 (1.0×
10−7 M) in MeOH at 25°C. The intensities of emission spectra
decreased gradually as the volume % of piperidine was increased from
0 to 1, 2, 4, 6, 9, 12, 15, and 20 vol%
increase in molar absorptivity. A red shift from 480 nm at 10°
C to 490 nm at 80°C was observed for 3 (1×10−5 M). Such
changes are indicative of the formation of H-aggregation of
these compounds in water at low temperature. The extent of
aggregation decreases as temperature increases resulting in an
increase in λmax and molar absorptivity.
Compounds 2 and 3 fluoresce in water and show an
excitation band with a maximum at 491 nm and an emission
band at about 590 nm; a very large Stokes shift of almost
100 nm. The effect of temperature on the fluorescent
properties of these compounds is dramatic. As temperature
was raised from 10°C to 80°C, about 14-fold increase in
emission intensity was observed for a 1×10−5 M solution of 2
Fig. 5 Effect of CH3COOH on fluorescence emission of 1 (1.0×
10−7 M) in MeOH/DCM (v/v=50/50)
to 475 nm as the concentration increases to 1.0×10−4 M.
Spectral changes in the visible region of 2 and 3 suggest the
formation of H-aggregates [41, 42] of these compounds in
water. Studies reported for other ionic aromatic dyes in
aqueous solution suggested that there is no optimum
aggregation size and no critical concentration for the
formation of aggregates [43–45].
Further evidence for the formation of H-aggregates is
provided by the temperature-dependent absorption spectra of
these compounds. As shown in Fig. 10, the λmax of absorption
of 2 (1×10−5 M) in water is red-shifted from 485 nm at 10°C
to 495 nm at 80°C. The red shift is accompanied by an
Fig. 7 Stern-Volmer plots of quenching of 1.0×10−7 M of 2 in MeOH
by piperidine at 25°C (Δ), 35°C (•), and 45°C (o)

J Fluoresc (2011) 21:213–222
217
Fig. 8 (Left) Stern-Volmer plots of quenching of 1.0×10−7 M of 2 in MeOH by N-ethylaniline at 35°C. (Right) A plot of the apparent quenching
constant ((Fo-F)/F[N-ethylaniline]) versus [N-ethylaniline]
(Figs. 11a and 12). At a low temperature, the aggregation of 2
in water results in significant self-quenching. The extent of
aggregation decreases at a higher temperature, consequently
reducing the extent of self-quenching.
The substitution of hydrogen at the 9-position of the
perylene-3,4-dicarboximide ring by bromine resulted in
very significant difference in the temperature-dependent
aggregation and fluorescence properties of 3. At 10°C,
the emission intensity of 3 (1.0×10−5 M) is significantly
lower than that of 2 at similar concentrations (Fig. 11b).
This is attributed to the bromine substitution that (1)
causes quenching of fluorescence by heavy atom effect
and (2) modulates the solubility and stacking of aromatic
rings, thereby, increases aggregation and self-quenching
of 3. More importantly, the fluorescence emission inten-
sity increases dramatically by about 28-fold as the
temperature of the solution increases from 10°C to 85°C
(Figs. 11b and 12).
In addition to temperature, the fluorescence emissions of
2 and 3 in aqueous solution can be varied by the addition of
a less polar solvent, such as methanol. As shown in Fig. 13,
the λmax of emission of 2 and 3 in methanol are slightly
blue-shifted (about 20 nm) compared to that in water. The
relaxation of the excited state dipole of fluorophores by
solvation of solvent dipoles will result in lower energy of
the excited state [38, 39]. Since stabilization of the excited
state dipole in methanol is less effective than in water,
emission in methanol is at higher energy or shorter
wavelength. In addition to different λmax values of
emission, the fluorescent intensities of 2 and 3 in methanol
are higher than that in water by about 8 and 25 times,
respectively. Several factors contribute to the lower fluo-
rescent emission intensities in water compared to methanol.
The molar absorptivities of 2 and 3 in water are lower than
those in methanol. Furthermore, the rate constants of non-
radiative decays of fluorophores are not the same in
different solvents. Most significantly, the aggregation of
these fluorophores in water results in reabsorption and self-
quenching of fluorescent emission.
Fig. 9 Series of offset visible spectra of (a) 2 of concentrations from
1.0×10−3 M (top spectrum) to 1.0×10−7 M (bottom spectrum) and (b)
3 of concentrations from 1.0×10−4 M (top spectrum) to 1.0×10−7
M
Using fluorescein (quantum yield of 1.0 in methanol
with 0.01 M KOH) as reference standard, the fluores-
(bottom spectrum) in water

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J Fluoresc (2011) 21:213–222
Fig. 10 Spectra showing the
effect of temperature on the uv-
vis absorption properties of (a) 2
(1×10−5 M) and (b) 3 (1×
10−5 M) in water. Spectra were
taken at increments of 10°C in
temperature
cence quantum yields of 2 and 3 in MeOH were
determined to be 0.50 and 0.41, respectively (Table 1).
The lower quantum yield observed for 3 is probably
caused by the presence of bromine which increases
fluorescence quenching by heavy atom effect. The average
quantum yields of the aggregates in water were also
determined. In consistent with the lower fluorescent
emission intensities in the steady state spectra observed
for these compounds in water, the average quantum yields
of the aggregates of 2 and 3 in water were found to be
lower than the quantum yields in methanol. Furthermore,
the quantum yields decrease as self-quenching increase
with aggregation at higher concentrations.
Conclusions
Overall, perylene-3,4-dicarboximide is an excellent scaffold for
constructing fluorophores with desired properties for sensing
applications. The solubility, aggregation, and fluorescence
properties can be modulated by the structure of the group
attached to the imide nitrogen and substituent on the aromatic
ring. Compounds 1–3 can be excited with visible light at
wavelengths of commercially available lasers and fluores-
cence emission can be observed without the need to remove
oxygen from the solution. The large Stokes shift permits easy
filtering of emission light from excitation light in studies by
fluorescence microscopy and spectroscopy techniques.
Fig. 11 Temperature-dependent
fluorescence excitation and
emission spectra of (a) 2 (1.0×
10−5 M) and (b) 3 (1.0×10−5 M)
in water. Spectra were taken at
increments of 5°C in tempera-
ture. Excitation spectra were
acquired at emission wavelength
of 586 nm and the emission
spectra were acquired at excita-
tion wavelength of 491 nm

J Fluoresc (2011) 21:213–222
219
synthesized by reaction of 9-bromo-(N-(2-(N’,N’-diethyla-
mino)ethyl)perylene-3,4-dicarboximide (4) with methyl p-
toluenesulfonate as described below.
N-(2-(N’,N’-diethyl-N’-methylammonium)ethyl)-9-bromo-
perylene-3,4-dicarboximide tosylate (3) Methyl p-toluene-
sulfonate (2.50 g, 13.5 mmol) was dissolved into 20 mL of
toluene. Then 9-bromo-2-(N,N-diethylamino)ethylperylene-
3,4-dicarboximide 4 (0.50 g, 1.0 mmol) was added and the
reaction mixture was refluxed overnight. After the reaction
mixture was cooled to room temperature, the solid was
collected by suction filtration and washed with toluene and
ether. The solid was dried under vacuum overnight and then
suspended into 50 mL of CHCl3. The suspension was
refluxed overnight. Then the resulting solid was collected by
suction filtration and dried over vacuum overnight to give 3
Fig. 12 Plot showing the effect of temperature on the fluorescent
emission intensity at λmax of aqueous solutions (1.0×10−5 M) of 2 and
3. For comparison of the relative increase in intensity, the emission
intensities are normalized with respect to the intensity at 10°C
1
(0.59 g, 86%). H NMR (400 MHz, CD3OD): δ=7.67 (d,
2H, 3J (H,H)=8.4 Hz, Ar-H), 7.63 (d, 1H, 3J (H,H)=9.6 Hz,
This study shows that the fluorescence emission of N-(2-
(N’,N’-diethylamino)ethyl)perylene-3,4-dicarboximide 1 is
partially quenched by photoinduced electron transfer from
the lone-pair electrons of its amino side chain. Fluorescence
emission is enhanced by protonation of the amino side
chain suggesting that 1 may serve as fluorescent probe for
acidic environment. Our studies show that 1 can detect
carboxylic acids in the μM concentration range. Quaterni-
zation of the amino side chain of 1 resulted in 2 with higher
fluorescent quantum yield and longer lifetime than 1. The
fluorescence emission of 2 is not affected by carboxylic
acids. The results of this research demonstrated that the
fluorescence emission of perylene-3,4-dicarboximide could
be switched on or off by controlling the availability of lone-
pair electrons of an amino group.
The ionic compounds 2 and 3 are soluble in water and
have potential applications as fluorescence probes of
temperature and solvent polarity. The fluorescence emission
intensity of 3 increases dramatically by about 28-fold as the
temperature of the solution increases from 10°C to 85°C. In
addition, the fluorescent intensities of 2 and 3 in methanol
are higher than that in water by about 8 and 25 times,
respectively. The 9-bromo substituent of 3 has substantially
change the extent of aggregation of the ionic perylene-3,4-
dicarboximides in water and resulted in a much larger
increase in fluorescence emission with temperature and
solvent polarity than 2.
Experimental
Fig. 13 Effect of solvent on the fluorescence emission spectra of (a) 2
(1×10−6 M) and (b) 3 (1×10−6 M). The emission spectra were
acquired at an excitation wavelength of 491 nm
Compounds 1 and 2 were synthesized according to proce-
dures described previously [28, 29]. Compound 3 was

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J Fluoresc (2011) 21:213–222
Φ of 3
Table 1 Quantum yields (Φ) of
2 and 3 in MeOH and water at
25°C
Entries
Solution
Φ of 2
1
2
3
4
In methanol
0.50 0.02
0.17 0.004
0.13 0.006
0.11 0.006
0.42 0.008
0.079 0.006
0.051 0.003
0.035 0.002
2×10−7 M in water
5×10−7 M in water
1×10−6 M in water
1×10−5 M in water
5a
5b
5c
at 80°C
at 25°C
at 10°C
0.13 0.003
0.021 0.0002
0.010 0.00009
0.072 0.001
0.0061 0.00009
0.0026 0.00004
Ar-H), 7.61 (d, 1H, 3J (H,H)=8.8 Hz, Ar-H), 7.60 (d, 1H, 3J
(H,H)=7.6 Hz, Ar-H), 7.52 (d, 1H, 3J (H,H)=7.6 Hz, Ar-H),
7.38 (d, 1H, 3J (H,H)=8.0 Hz, Ar-H), 7.28 (d, 1H, 3J (H,H)=
9.2 Hz, Ar-H), 7.27 (t, 1H, 3J (H,H)=8.4 Hz, Ar-H), 7.21 (d,
1H, 3J (H,H)=8.0 Hz, Ar-H), 7.18 (d, 2H, 3J (H,H)=8.0 Hz,
CH2), 2.82 (t, 2H, 3J (H,H) ) 7.5 Hz, β-CH2), 2.72 (q, 4H, 3J
3
(H,H) ) 7.0 Hz, -NCH2CH3), 1.14 (t, 6H, J (H,H) ) 8.0 Hz,
CH3) ppm; 13C NMR (125 MHz, CDCl3) δ=163.7, 163.7,
136.1, 136.0, 132.7, 131.3, 1,312, 131.1, 130.0, 129.3, 129.3,
128.7, 128.0, 126.2, 126.0, 124.1, 123.4, 121.2, 120.5, 120.2,
3
3
Ar-H), 7.14 (d, 1H, J (H,H)=7.6 Hz, Ar-H), 4.30 (t, 2H, J
(H,H)=7.6 Hz, -CH2), 3.54 (m, 4H, -N-(CH2)2-), 3.46 (t, 2H,
-CH2-N-(CH2)2), 3.16 (s, 3H, -N-CH3), 2.30 (s, 3H, CH3 of
50.0, 47.9, 38.2, 12.5 ppm; UV (CHCl3, 1.0×10−5 M) λmax
=
475 (ε=33,150), 497 (ε=34,100) nm; HRMS (FAB, m/z)
Calcd 499.1021, found 499.1004; mp 246°C.
3
p-toluenesulfonate), 1.47 (t, 6H, J (H,H)=7.2 Hz, -CH2-
Deuterated trifluoroacetic acid (TFA-d, D-99.5%), deu-
terated chloroform (CDCl3, D-99.8%), and deuterated
methanol (CD3OD, D-99.8%) were purchased from Cam-
bridge Isotopes. Formic acid (HCOOH(aq) conc. +88%)
and glacial acetic acid (100.0%) were purchased from
ACROS Organics and Fisher Scientific, respectively.
1H and 13C NMR spectra were acquired on either a
Varian MR 400 MHz or a GE QE 300 MHz spectrometer.
Infrared spectra were recorded on a Perkin-Elmer Spectrum
2000 FT-IR spectrometer. Spectra of powdered samples
were obtained in the form of KBr pellets prepared with
dried KBr using a mini-press from SpectraTech, Inc. Mass
spectra were recorded with Waters Micromass XQ detector
using ESI+ and ESI−. Electronic spectra were obtained with
a dual-beam Perkin Elmer Lambda 950 and software UV-
WIN Lab version 5.1.5.
Fluorescence spectra were acquired using a Jobin-Yvon
Horiba Fluorolog 3–222 spectrophotometer and software
FluorEssence. Lifetime measurement were performed at
25°C using the Fluorolog 3 equipped with a NanoLED-492,
FluoroHub TCSPC, a single photon detection cooled
photocathode TBX-05, and Datastation DAS6 Foundation
Software. The lifetime of fluorescein in MeOH was
determined under the same conditions for comparison and
was found to be 4.1 ns. All studies were preformed without
purging the solutions with inert gas to remove oxygen.
Quantum yields were determined according to the method
reported by Williams and his coauthors [46]. Solutions of
three concentrations (2.0×10−7 M, 5.0×10−7 M, and 1.0×
10−6 M) were prepared for fluorescein in MeOH (0.01 N
KOH) and perylene-3,4-dicarboximide 1–3 in the solvents to
be studied. The UV-vis absorption spectra of solutions of
both fluorescein and 1–3 were acquired using a 10 or 1-cm
CH3) ppm; 13C NMR (100 MHz, CF3COOD): δ=168.3,
167.7, 146.4, 140.7, 140.5, 138.6, 135.2, 135.2, 134.0, 133.9,
133.2, 132.9, 131.5, 131.2, 130.3, 130.0 129.4, 129.2, 127.9,
127.2, 127.0, 122.8, 122.4, 120.0, 119.9, 60.1, 58.3, 49.7,
36.4, 21.7, 8.9 ppm; UV (MeOH, 1.0×10−5 M) ) λmax=262
(ε=29,700), 338 (ε=2,800), 354 (ε=3,520), λmax=493 (ε=
35,500) nm, (water, 1.0×10−5 M) ) λmax=360 (ε=2,820), 481
(ε=16,500) nm; MS (ESI+, m/z) Calcd for [C29H26BrN2O2]+:
513.12; Found: 513.28.
N-(2-N’,N’-diethylamino)ethyl)-9-bromoperylene-3,4-dicar-
boximide (4) 2-(N,N-diethylamino)ethylperylene-3,4-dicar-
boximide (1) (3.01 g, 7.15 mmol) and 150 mL of
concentrated sulfuric acid were mixed in a 500-mL round-
bottom flask. The mixture was cooled to −10°C, then
0.48 mL of Br2 was added slowly with a 1-mL syringe.
After the reaction mixture was stirred at −10 to −5°C for 4 h,
it was poured into 750 mL of cold distilled water in a 2,000-
mL flask in an ice bath. About 400 mL of 30% NH4OH(aq)
was added dropwise until the pH was 8–9. A bright red solid
formed was filtered and washed with 300 mL of 5%
NH4OH(aq) and then distilled water. The solid was dried in
an vacuum oven at 110°C. The bright red solid was purified
by recrystallization in 100 mL of 1% triethylamine in DMF
solution. The filtered solid was washed with ethyl ether and
1
dried under vacuum to yield 4 (2.96 g) in 83% yield. H
NMR (500 MHz, CDCl3) δ=8.30 (d, 1H, 3J (H,H) ) 8.0 Hz,
Ar-H), 8.27 (d, 1H, 3J (H,H) ) 8.5 Hz, Ar-H), 8.09 (d, 2H, 3J
(H,H) ) 8.5 Hz, Ar-H), 8.01 (d, 1H, 3J (H,H) ) 8.0 Hz, Ar-H),
7.93 (d, 1H, 3J (H,H) ) 8.0 Hz, Ar-H), 7.80 (d, 1H, 3J (H,H) )
8.0 Hz, Ar-H), 7.66 (d, 1H, 3J (H,H) ) 8.5 Hz, Ar-H), 7.51 (d,
1H, 3J (H,H) ) 8 Hz, Ar-H), 4.27 (t, 2H, 3J (H,H) ) 7.5 Hz, α-

J Fluoresc (2011) 21:213–222
221
9. Métivier R, Christ T, Kulzer F, Weil T, Müllen K, Basché Th
(2004) Single-molecule spectroscopy of molecular aggregates at
low temperature. J Lumin 110:217–224
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Charge transfer processes in conjugated triarylamine-oligothiophene-
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K, Hofkens J, De Schryver FC (2003) Intramolecular directional
forester resonace energy transfer at the single-molecular level in a
dendritic systems. J Am Chem Soc 125:13609–13617
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transfer in a naphthaleneimide-peryleneimide-terrylenediimide-
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(2002) Synthesis of perylene-porphyrin building blocks and rod-
like oligomers for light-harvesting applications. J Mater Chem
12:3438–3451
18. Tomizaki K, Thamyongkit P, Loewe RS, Lindsey JS (2003)
Practical synthesis of perylene-monomide building blocks that
possess features appropriate for use in porphyrin-based light-
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path length cuvette. Electronic spectra were obtained with a
dual-beam Perkin Elmer Lambda 950 and software UV-WIN
Lab version 5.1.5. Fluorescence spectra were acquired using
a Jobin-Yvon Horiba Fluorolog 3–222 spectrophotometer
and software FluorEssence. Emission in range from 460 nm
to 750 nm was acquired when the sample in a 1-cm path
length fluorescence cuvette was excited at 450 nm. The
integrated fluorescence intensity (that is, the area of the
fluorescence spectrum from 490 nm to 750 nm) was
calculated and note down from all fluorescence spectrum.
A graph of integrated fluorescence integration vs absorbance
(at 450 nm) was plotted for each compound. The slopes of
the graphs are proportional to the quantum yield of the
different samples. Absolute values were calculated according
to the following equation [46]:
À
Á
ΦX ¼ ΦSTðGradX=GradSTÞ η2X=ηS2T
Where Φ is the fluorescence quantum yield, ST and X
denote standard and test respectively, η is the refractive
index of the solvent, and Grad is the slope from the plot of
integrated fluorescence intensity vs absorbance.
Acknowledgments We thank the National Science Foundation
(DMR-0405532 and DMR0804897) for funding this research. Any
opinions, findings, and conclusions or recommendations expressed in
this material are those of the authors and do not necessarily reflect the
views of the National Science Foundation.
19. Muthukumaran K, Loewe RS, Kirmaier C, Hindin E, Schwartz
JK, Sazanovich IV, Diers JR, Bocian DF, Hotlen D, Lindsey JS
(2003) Synthesis and exciated-state photodynamics of a perylene-
monoimide-oxochlorin dyad. A light-harvesting array. J Phys
Chem B 107:3431–3442
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