Controlling UV/vis absorption and stokes shifts in highly fluorescent chromophores by molecular dynamics in targeted construction of dyads

Article abstract of DOI:10.1021/jo301417p

Perylenedicarboximides were interlinked in their free peri-position to form dyads where the UV/vis absorptivity was amplified by exciton effects and the strong fluorescence bathochromically shifted by molecular dynamics. Applications of this type of dye w

Full text of DOI:10.1021/jo301417p

Article
pubs.acs.org/joc
Controlling UV/vis Absorption and Stokes Shifts in Highly
Fluorescent Chromophores by Molecular Dynamics in Targeted
Construction of Dyads
Heinz Langhals* and Alexander Hofer
Department of Chemistry, LMU University of Munich, Butenandtstrasse 13, D-81377 Munich, Germany
S
* Supporting Information
ABSTRACT: Perylenedicarboximides were interlinked in their free peri-position to form dyads
where the UV/vis absorptivity was amplified by exciton effects and the strong fluorescence
bathochromically shifted by molecular dynamics. Applications of this type of dye with such
increased Stokes shifts were discussed.
we targeted dyads where X is an element of structure of a
chromophore. A ring-closure from X to R allows the construc-
tion of rigid structures suitable for high fluorescence quantum
yields.
INTRODUCTION
■
Rigid aromatic systems are preferred as basic structures for the
development of highly fluorescent materials.1 Small Stokes
shifts are generally observed for such fluorophores because the
electronic excitation does not induce significant geometric altera-
tions and the conditions are similar in the electronic transitions
both for absorption and fluorescence, respectively. On the other
hand, strongly fluorescent materials with large Stokes shift are of
interest for many fields such as laser dyes,2 solar energy collec-
tors,3 analytics,4 and many more applications because reabsorp-
tion of the fluorescent light is avoided. We intend to solve this
problem with the development of dyads with dynamic inter-
links. Moreover, the interaction of such proximate chromophores
may cause exciton effects as a consequence of optical resonance
where Davidov splitting and alterations of the absorptivities,
respectively, can be additionally applied for the control of the
UV/vis spectra.
We made suitable dyads with the perylene dye series5,6
because of their high fluorescent quantum yields7 and chemical
and photochemical stability8 and started synthesis with the
perylene anhydride carboximides9 1 where the long chain sec-
alkyl substituent R = 1-hexylheptyl (swallow-tail substituent)
was used to increase solubility.10 A copper-induced decarbox-
ylation11 allowed the direct preparation of 2a in 30% yield in
air-equilibrated solution; see Scheme 1. The alkyl chains of R at
the nitrogen atoms were further extended to 1-nonyldecyl12 in
2b in order to increase the solubility and diminish the tendency
of aggregation, respectively, in weakly solubilizing media; other
derivatives of 2 were described previously in the literature as
intermediates for syntheses,13 however, without reporting any
special photophysical properties.
Some 3 was formed as a product of reduction; 3 became the
main product by thorough exclusion of oxygen where the qua-
lity of applied copper powder was essential for high yields; com
pare to ref 12. 3 was additionally converted to 2 by bromination
to form 4 and, finally, palladium-mediated coupling. Hydrolysis
of 2 by means of KOH in tert-butyl alcohol9 was not successful.
On the other hand, such a hydrolysis of 4 proceeded to form 6,
and a palladium-mediated coupling allowed the preparation of
5. Finally, the bromination of the well accessible12,15 7 was an
alternative for the preparation of 6 and 5, respectively. 5 and 7,
respectively, react with aqueous potassium hydroxide to form
the water-soluble 8 and potassium perylene-3,4-dicarboxylate,
respectively.
RESULTS AND DISCUSSION
■
We estimated that peri-linked binaphthyls would be suitable
structures for dynamically increased Stokes shifts according to
Figure 1 where there is a tendency from steric effects for the
two naphthyl units in the So ground state to be orthogonal. The
light absorption (ℏν) means a fast, vertical electronic transition
to the S1 state preserving the initial geometry. The subsequent
relaxation to the S1′ state is fast enough not to affect the
electronic excitation. Bathochromically shifted fluorescence
(−ℏν′) proceeds as a vertical electronic transition to the elec-
tronic ground state So′ where a further relaxation closes the
circle to the initial state So. One can expect that the S1′ state is
more planar than the initial state So because the π-system is less
firm as a consequence of the electronic excitation and the con-
jugation between the naphthalene units becomes more impor-
tant, forcing the two systems in plane. Naphthalene is colorless
because of UV absorption, and a bathochromic shift is neces-
sary for light absorption in the visible region. As a consequence,
Furthermore, we expanded the perylene dye 9 laterally to the
more bathochromically absorbing and highly fluorescent
imidazolo derivative 10 according to Scheme 2 and hydrolyzed
Received: July 30, 2012
© XXXX American Chemical Society
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Figure 1. Left: Increase of the Stokes shift of fluorescent materials by fast dynamic processes in binaphthyls: Start with the initial state So, vertical
electronic transition by light absorption (ℏν) to the electronically excited state S1, relaxation to the excited state S1′, bathochromic fluorescence
(−ℏν′) to the ground state So′, and relaxation back to the initial state So. X, R: Structure elements of chromophores. Right: Schematic energy
diagram (E) of electronic transitions and relaxation processes; overlaying vibronic processes are omitted because of clearness.
a
Scheme 1. Synthesis of the Dyad 2 (1a−4a: R = 1-hexylheptyl, 1b−4b: R = 1-nonyldecyl)
a
Reagents and conditions: (i) Cu, 3-picoline, air-equilibrated, 28%; (ii) Cu, 3-picoline, exclusion of air and moisture; (iii) Br2, I2, H2SO4; (iv)
Pd(OAc)2, (C4H9)4NBr, NEt3, toluene, 34%; (v) (1) KOH, tert-butyl alcohol (2) HCl, (vi) KOH/H2O.
one carboximide ring to obtain 11.14 A copper-mediated
decarboxylation gave 12 where a coupling to 14 could not be
detected (the yield of 12 depends on the quality of the copper
powder). As an alternative, 12 was brominated to form 13 and,
finally, palladium-induced coupled to the dyad 14. The hetero
dyad 16 was prepared starting with 4 and the exchange of the
bromine atom by a pinacolyl boronic unit in 15, where a cross
coupling with 13 gave the hetero dyad 16.
The UV/vis absorption spectrum of 3 is typical of perylene
dicarboximides12 with a double maximum and a strong yellow
fluorescence (≈100% quantum yield); see Figure 2. The arrange-
ment of two chromophores in 2 induces both a bathochromic
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a
Scheme 2. Synthesis of the Dyad 14 and 16 (R = 1-hexylheptyl)
a
Reagents and conditions: (i) sodium amide, benzonitrile; (ii) KOH, tert-butyl alcohol; (iii) Cu, 3-picoline, 48%; (iv) Br2, chloroform, 88%; (v)
Pd(OAc)2, (C4H9)4NBr, NEt3, toluene, 60%; (vi) pinacole diborane, PdCl2(dppf), KOAc, 1,4-dioxane, 63%; (vii) Pd[P(C6H5)3]4, 2 M aqueous
Na2CO3, ethanol, toluene, 60%.
shift and an appreciable amplification of the light absorption by
co-operative exciton interactions, where the molar absorptivity
ε was increased from 31600 L·mol·cm−1 of 3 to even 96000 for
2, and the spectrum was dominated by a strong additional
exciton band in 2; only a doubling of the molar absorptivity
would be expected for simple additive effects in the dyad,
whereas exciton effects cause a further increase to more than
three times the absorptivity of a single chromophore (compare
to ref 16). Dye 3a is highly fluorescent, where a quantum yield
of ≈100% was found in chloroform. The high fluorescence
quantum yield is preserved in the bichomophore 2a (≈100%)
and indicates that the mobile single bond between the chro-
mophores does not interfere with high fluorescence quantum
yields. The Stokes shift of 2a is appreciably increased com-
pared with the monochromophore 3a. We interpret this
photophysical effect in terms of a dynamic process of the
Figure 2. UV/vis absorption (left) and fluorescence spectra (right) of
2a (solid lines) and 3a (dotted lines) in chloroform.
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Figure 3. Left from top to bottom: The calculated geometries (DFT, B3LYP) of the ground state of 3, the equilibrated LUMO of 2, and the HOMO
of 2. Right from top to bottom: The LUMO of 3, the HOMO of 3, the equilibrated LUMO of 2, and the HOMO of 2.
electronically excited state of the dye molecules according to
Figure 1. The ground state of 2 is characterized by steric effects
as the driving force to an orthogonal arrangement of the two
chromophores; this causes an electronic decoupling of the
π-systems, however, leaves exciton effects unaffected. We
calculated the geometry of 2 quantum chemically (DFT) and
obtained a dihedral angle of 76° (C9a−C9−C9′−C9a′). The
vertical electronic transition by light absorption preserves this
geometry; however, the π-system becomes less firm because
there is one additional nodal plane of the orbital occupying the
excited electron and the interchromophore bond gets more
π-character. As a consequence, the excited molecule relaxes to a
more planar state with lower energy where the electronic transi-
tion of fluorescence becomes bathochromically shifted and the
Stokes shift is increased, respectively. We calculated the geom-
etry of the excited state (RTD-CAM-B3LYP-FC) and found a
lowered interplanar angle of 53°. DFT calculations of the trip-
let state with a less firm π-system gave a similar result (46°);
involved orbitals and geometries are shown in Figure 3.
The coupling of two chromophores in 14 causes a slight
additional bathochromic shift and an appreciable increase of the
absorptivity by exciton effects similarly to 2. The strong
fluorescence (close to 100% quantum yield) is bathochromi-
cally shifted such as in 2 and causes an increase of the Stokes
shift, respectively, where we make the mechanism of Figure 1
responsible for this effect; the high fluorescence quantum yield
indicates that there is no interference either by the dynamic of
the flexible interlinking single bond or by the bathochromicity
of fluorescence extending into the NIR. The bathochromic shift
of the fluorescence is so pronounced that the visual fluores-
cence of 14 is weaker than that of 12 and 2, respectively, because
despite the high fluorescence quantum yield, an appreciable part
of the fluorescence light is in the invisible and the spectral region
and region of low eye sensitivity.
We calculated the geometry of both the ground state and the
excited state in the same manner as for 2 and found a similar
orthogonal geometry for the ground state of 14: dihedral
angle of 90° and only a slight change for the excited state; this
may be a consequence of dipole−dipole interactions of the
annelated heterocyclic rings. The anhydride 7 is strongly
fluorescent (quantum yield close to 100%) and is of special
interest because it consists only on C, H, and O and may be
applied as a nitrogen-free fluorescent dye. As a consequence,
we coupled two chromophores to obtain 5 in order to get a
structure suitable for the mechanism according to Figure 1.
The UV/vis spectra in Figure 5 indicate an amplified UV/vis
absorption by exciton interactions and an increased Stokes
shift by the dynamic process according to Figure 1 in com-
plete analogy to the carboximides 2 and 14, respectively; 7
exhibits a bright orange fluorescence with a quantum yield
close to 100% in chloroform. Quantum chemical calculations
(DFT, B3LYP) indicate a dihedral angle of 76° for the ground
state and 48° for the first excited state (45° for the triplet),
verifying the concept of the dynamic increase of the Stokes
shift. The anhydride 7 can be ring-opened by means of diluted
aqueous KOH to form the water-soluble 8. The fluorescence
quantum yield of such aqueous solutions is appreciably lower
than for 2, 14, and 7; however, the dynamics for the increase
of the Stokes shift proceeds for this tetraanion in the aqueous
phase in the same way as with the other dyads, indicating that
We tested the more general applicability of the concept of
Figure 1 and prepared the imidazoloperylene derivative 12 where
the transversal extension by an imidazolo ring causes a batho-
chromic shift of the absorption compared with 3 and a bright red
fluorescence with a quantum yield close to 100%; see Figure 4.
Figure 4. UV/vis absorption (left) and fluorescence spectra (right) of
14 (straight lines) and 12 (dotted lines) in chloroform.
D
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Figure 5. Left from top to bottom: The calculated geometries (DFT, B3LYP) of the ground state of 12, the equilibrated LUMO of 14, and the
HOMO of 14. Right from top to bottom: The LUMO of 12, the HOMO of 12, the equilibrated LUMO of 14, and the HOMO of 14.
the aqueous phase is generally suitable for dynamics accord-
ing to Figure 1.
Finally, the concept for the increase of the Stokes shift by the
dynamic of peri-linked dyads was extended to hetero dyads.
This is of special interest because Forster resonance energy
̈
transfer (FRET) may proceed from the hypsochromically absorb-
ing chromophore to the bathochromically absorbing and fluores-
cent chromophore where the dynamic process may increase the
Stokes shift of the latter. As a consequence, one may construct
broad-band absorbing dyads with increased Stokes shifts. Dyad
16 fulfills these conditions because of the linking of two highly
fluorescent chromophores based on 3 and 12. The UV/vis
spectra reported in Figure 6 correspond to an addition of the
spectra of 3 and 12 where the bathochromically absorbing chro-
mophore of 12 seems to dominate in 16. No hypsochromic fluores-
cence is observed even with the predominant electronic exci-
tation of the more hypsochromically absorbing component
based on 3, indicating an efficient energy transfer according to
Figure 6. UV/vis absorption (left) and fluorescence spectra (right) of
3 (dashed lines), 12 (dotted lines), and 16 (straight lines) in
chloroform.
CONCLUSIONS
■
Forster’s mechanism (FRET). The Stokes shift of 16 is increased
̈
We conclude that the linking of aromatic systems in peri-
positions to form dyads allows the construction of fluorescent
dyes with increased Stokes shifts by molecular dynamics where
the molecules undergo of a cyclic process to give high fluores-
cence quantum yields. Perylenedicarboximides linked in the free
peri-position to dyads are good candidates for such fluorescent
compared with 12, indicating a dynamic process although the
effect is not as pronounced as with the homo dyads. A dihedral
angle of 78° was calculated for the ground state and a diminished
angle for the excited state of 55°; this corresponds with the
Stokes shift.
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(w), 2922.4 (w), 2852.8 (w), 2348.5 (w), 1749.7 (vs), 1717.9 (s),
1653.8 (w), 1590.4 (s), 1568.6 (s), 1521.8 (w), 1498.7 (w), 1457.6
(w), 1408.9 (w), 1370.7 (w), 1339.6 (s), 1306.1 (w), 1282.3 (s),
1231.8 (w), 1191.5 (w), 1151.6 (w), 1130.3 (m), 1018.2 (s), 995.7 (s),
902.1 (w), 857.4 (w), 834.1 (w), 807.8 (s), 762.0 (m), 739.6 (s), 675.2
(w), 657.1 cm−1 (w). 1H NMR (600 MHz, CDCl3, 25 °C, TMS): δ =
7.65−7.80 (m, 4 H), 7.94−7.99 (m, 2 H), 8.25−8.71 ppm (m, 12 H).
13C NMR (150 MHz, CDCl3 and trace of paraffin, 25 °C, TMS): δ =
123.1, 123.3, 123.4, 123.5, 126.5, 129.6, 130.0, 130.5, 131.2, 132.0,
134.3, 135.3, 136.5, 146.2, 146.9, 164.3 ppm. UV/vis (CHCl3): λmax
(ε) = 354.0 (16670), 489.0 (61300), 511.0 nm (59600). Fluorescence
(CHCl3, λmax = 490.4 nm): λmax (Irel) = 548.5 (1.00), 586.8 nm (0.87).
Fluorescence quantum yield (λexc = 490.4 nm, E490.4 nm/1 cm = 0.0192,
CHCl3, reference 9a with Φ = 1.00): 0.78. MS (DEI+, 70 eV) m/z
(%): 643 (21) [M+ + H], 642 (45) [M+], 336 (23), 323 (26), 322
(100) [M+ −C22H8O3], 278 (24), 250 (76), 249 (28), 248 (42), 128
(25), 125 (29), 124 (43), 97, (25), 85 (46), 83 (83), 82 (19), 71 (21),
70 (20), 69 (54), 57 (37), 55 (57), 43 (28), 41 (25). HRMS (DEI+,
70 eV, C44H18O6): Calcd m/z: 642.1103; found m/z: 642.1101,
Δ = −0.0002.
dyes because of their high photostability and fluorescence
quantum yields where the extension of the aromatic system
allows the adaption of the UV/vis spectra. Such systems with
increased Stokes shifts may be of interest for applications where
the reabsorption of the fluorescent light by the chromophore is
problematic such as for laser applications,2 for fluorescent planar
solar-light concentrators3,17 where the behavior in glassy matrixes
has to be investigated, for analytical applications, and even for
strong visual impressions of fluorescence.
EXPERIMENTAL SECTION
■
General. All FAB spectra were recorded in 3-nitrobenzyl alcohol as
the matrix. The interpretation of NMR signals was verified with
carbon−proton and proton−proton correlation methods.
9,9′-Bis[perylene-3,4-dicarboxylic-3,4-(1-nonyldecylimide)]
(2b). Copper powder (10.43 g, 164.17 mmol) was disperged in 3-
picoline (1400 mL), stirred at 80 °C for 24 h, treated with N-(1-
nonyldecyl)-3,4,9,10-perylenetetracarboxylic-9,10-anhydride-3,4-imide
(21.6 g, 32.84 mmol), and stirred at 140 °C for 24 h. The mixture was
allowed to cool and poured into 2 M HCl (4000 mL). The solid was
collected by vacuum filtration (Buchner filter), dried at 110 °C in air,
̈
and purified by column separation (silica gel, chloroform; second,
strongly reddish orange fluorescent band). Yield 3.55 g (28%) of a
reddish orange solid, mp >250 °C. Rf (silica gel, chloroform/isohexane
̃
1:1): 0.95. IR (ATR): ν = 3394.9 (w), 3297.6 (w), 3052.8 (w), 2952.5
12: Copper powder (1.28 g, 20.1 mmol) in 3-picoline (160 mL)
was stirred with the exclusion of moisture and air (nitrogen) at 85 °C
for 5 h and treated with 11 (2.50 g, 4.02 mmol). The mixture was
heated to reflux (165 °C bath) for 24 h, allowed to cool, and treated
with 2 M aqueous HCl (500 mL). The solid was collected by vacuum
filtration (D4 glass filter), dried at 110 °C for 16 h, and purified by
column separation (silica gel, chloroform). Yield: 1.20 g (48%) of a
violet solid, mp 167 °C. Rf (silica gel, chloroform): 0.85. IR (ATR):
(m), 2919.3 (s), 2850.6 (s), 2587.3 (w), 2238.9 (w), 1922.8 (w),
1688.8 (s), 1647.8 (s), 1594.1 (s), 1573.6 (s), 1501.6 (m), 1456.0 (m),
1404.7 (m), 1371.5 (w), 1343.9 (s), 1306.2 (m), 1285.2 (m), 1249.4
(m), 1217.9 (m), 1205.9 (m), 1171.3 (m), 1156.5 (m), 1132.5 (w),
1110.2 (w), 1044.5 (m), 963.5 (w), 945.2 (w), 898.9 (w), 850.2 (w),
836.6 (w), 803.7 (s), 788.5 (m), 747.4 (m), 731.8 (w), 720.7 (w),
669.7 cm−1 (w). 1H NMR (600 MHz, CDCl3, 25 °C, TMS): δ = 0.84
3
(t, J(H,H) = 7.0 Hz, 12 H), 1.21−1.37 (m, 56 H), 1.85−1.90 (m, 4
̃
ν = 3422 (w), 2953.6 (m), 2920.0 (m), 2853.1 (m), 1725.5 (m), 1673.9
H), 2.24−2.30 (m, 4 H), 5.12−5.24 (m, 2 H), 7.48−7.57 (m, 4 H),
3
(s), 1635.9 (vs), 1619.6 (vs), 1564.2 (s), 1564.2 (m), 1534.5 (w),
1486.8 (w), 1486 (w), 1466.8 (m), 1453.8 (m), 1410.6 (w), 1397.0
(m), 1376.3 (w), 1340.2 (vs), 1318.2 (m), 1279.0 (s), 1250.1 (s),
1226.0 (m), 1155.9 (w), 1118.1 (m), 1068.4 (w), 1053.3 (m), 1025.4
(w), 1001.5 (w), 951.9 (w), 939.8 (w), 920.3 (w), 893.4 (w), 878.1
(w), 831.4 (m), 809.9 (s), 775.6 (m), 759.4 (s), 724.4 (w), 703.2(w),
682.2 (s) cm−1. 1H NMR (600 MHz, CDCl3, 25 °C): δ = 0.84 (t, 3J =
7.0 Hz, 6 H), 1.20−1.48 (m, 16 H), 1.88−2.00 (m, 2 H), 2.28−2.40
(m, 2 H), 5.21−5.34 (m, 1 H), 7.58 (t, 3J = 7.8 Hz, 2 H.), 7.85 (d, 3J =
7.72 (d, J (H,H) = 7.6 Hz, 2 H), 8.66−8.55 (m, 4 H), 8.58 (d,
3
3J(H,H) = 8.1 Hz, 2 H), 8.45 (t, J(H,H) = 8.0 Hz, 4 H). 13C NMR
(150 MHz, CDCl3, 25 °C, TMS): δ = 14.0, 22.6, 27.0, 29.3, 29.5, 31.8,
32.4, 54.5, 120.4, 120.5, 123.1, 123.8, 126.6, 127.3, 128.3, 129.2, 129.6,
129.6, 130.0, 131.2, 132.0, 133.7, 136.6, 140.4, 164.1, 165.1 ppm. UV/
vis (CHCl3): λmax (Erel) = 495.6 (sh, 0.68), 526.8 (1.00). Fluorescence
(CHCl3, λexc = 495.6): λmax (Irel) = 597.1 (1.00). Fluorescence
quantum yield (λexc = 495.6, E491 nm/1 cm = 0.0151, CHCl3, reference 9a
with Φ = 1.00): ≈1.00. MS (FAB−): m/z (%): 1173.7 [M]‑ (11). MS
(FAB+): m/z (%): 1173.7 [M + H]+ (7). HRMS (FAB+, quadrupole,
C82H97N2O4, M+ + H): Calcd 1173.7404, found 1173.7450, Δ =
+0.0046. C82H96N2O4 (1172.7): Calcd C 83.92, H 8.24, N 2.39; C
83.93, H 8.28, N 2.38.
3
3
8.0 Hz, 2 H.), 8.32 (d, J = 8.1 Hz, 2 H), 8.35 (d, J = 7.4 Hz, 2 H),
8.50 (br, 2 H), 10.54 (d, 3J(H,H) = 7.6 Hz, 1 H), 11.46 ppm (s, 1 H).
13C NMR (150 MHz, CDCl3, 25 °C): δ = 14.0, 22.6, 27.1, 27.2, 29.3,
29.7, 31.8, 32.4, 32.6, 118.3, 123.5, 123.8, 126.4, 127.3, 127.4, 128.2,
128.7, 129.2, 129.5, 130.5, 130.8, 131.5, 133.7 ppm. UV/vis (CHCl3):
λmax (ε) = 357.4 (7400), 376.4 (9900), 412.8 (11000), 432.8 (14500),
489.6 (11800), 525.6 (29900), 561.8 nm (39800). Fluorescence
(CHCl3, λmax = 525.0 nm): λmax (Irel) = 581.8 (1.00), 633.0 (0.58),
692.6 nm (0.12). Fluorescence quantum yield (λexc = 525.0 nm,
E525.0 nm/1 cm = 0.0168, CHCl3, reference 9a with Φ = 1.00): 0.96. MS
(DEI+, 70 eV): m/z (%): 620.3 (32.8) [M + H]+, 619.3 (69.1) [M+],
438.1 (52.6), 437.1 (100), 322.1 (13.0), 321.1 (30.7). HRMS (DEI+,
C42H41N3O2): Calcd m/z: 619.3199, found m/z: 619.3185, Δ =
−0.0014. C42H41N3O2 (619.3): Calcd C 81.37, H 6.67, N 6.78; found
C 81.49, H 6.86, N 6.75.
5: 9-Bromoperylene-3,4-dicarboxylic anhydride (6, 300 mg, 0.748
mmol) and freshly distilled and anhydrous toluene (40 mL) were
heated at 70 °C with thorough exclusion of air and moisture (argon
atmosphere) and treated with palladium(II) acetate (129 mg, 0.576
mmol) and tetrabutylammonium bromide (424 mg, 1.32 mmol). The
mixture was heated at 100 °C, treated with triethylamine (2 mL),
stirred at 120 °C for 12 h, allowed to cool, and treated with 2 M
aqueous HCl. The precipitate was collected by vacuum filtration (D4
glass filter), washed with distilled water, dried at 110 °C for 16 h, and
purified by column separation (silica gel, chloroform/acetic acid 100:1;
second, red band). Yield 81.7 mg (34%) of a dark red solid, mp >250 °C.
13: 12 (540 mg, 0.871 mmol) was disperged in chloroform, heated
at 40 °C, and treated with Br2 (0.18 mL, 1.60 mmol). The mixture was
stirred at 40−50 °C for 2.5 h and evaporated. The residue was purified
by column separation (silica gel, chloroform). Yield: 536 mg (88%),
̃
mp 186−187 °C. Rf (silica gel, chloroform): 0.75. IR (ATR): ν =
3412.6 (w), 3073.6 (w), 2953.0 (m), 2920.2 (s), 2853.6 (s), 1730.3
(w), 1708.5 (w), 1678.3 (s), 1636.3 (vs), 1619.5 (vs), 1605.4 (vs),
1591.7 (s), 1560.3 (s), 1534.2 (m), 1520.2 (w), 1504.2 (w), 1485.8
(m), 1453.4 (s), 1408.2 (m), 1393.6 (w), 1341.7 (vs), 1321.9 (vs),
1294.2 (m), 1282.3 (w), 1255.6 (s), 1222.5 (m), 1204.9 (m), 1170.3
(w), 1157.0 (w), 1116.0 (w), 1054.3 (w), 968.2 (w), 951.8 (w), 917.7
̃
Rf (silica gel/chloroform): 0.12. IR (ATR): ν = 3091.2 (w), 3052.0
F
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(w), 881.9 (w), 835.7 (w), 821.5 (w), 802.9 (m), 775.2 (w), 749.8 (s),
1.45 (s, 9 H, 12 H), 1.80−1.88 (m, 2 H), 2.20−2.29 (m, 2 H), 5.14−
5.22 (m, 1 H), 7.63 (t, 3J(H,H) = 7.9 Hz, 1 H), 8.16 (d, 3J(H,H) = 7.9
Hz 1 H), 8.35−8.43 (m, 4 H), 8.50−8.60 (m, 2 H) 8.38 (d, 3J(H,H) =
8.3 Hz, 1 H). 13C NMR (150 MHz, CDCl3, 25 °C): δ = 14.0, 22.6,
25.0, 27.0, 29.2, 31.8, 32.4, 54.4, 84.2, 120.2, 120.7, 122.5, 123.4, 126.6,
127.2, 127.7, 129.0, 129.8, 131.5, 131.7, 136.2, 138.0 ppm. UV/vis
(CHCl3): λmax (Erel) = 488.6 (0.96), 514.8 nm (1.00). Fluorescence
(CHCl3, λmax = 488.6 nm): λmax (Irel) = 546.5 (1.00), 587.5 nm (0.79).
Fluorescence quantum yield (λexc = 488.6 nm, E488.6 nm/1 cm = 0.0115,
CHCl3, reference 9a with Φ = 1.00): 0.82. MS (FAB+): m/z (%):631.4
(9.2) [M+ + 2H], 630.4 (42.8) [M+ + H], 629.4 (100) [M+], 628.4
(21.7), 448.2 (42.6), 447.2 (84.4), 446.2 (20.0), 348.1 (11.2), 347.1
(14.7), 84.9 (15.3), 82.9 (24.9). HRMS (FAB+, C41H48BNO4): Calcd
m/z: 629.3676, found m/z: 629.3678, Δ = +0.0002.
1
706.2 (w), 684.2 (s) cm−1. H NMR (600 MHz, CDCl3, 25 °C): δ =
0.84 (t, 3J = 7.0 Hz, 6 H), 1.21−1.42 (m, 16 H), 1.85−1.93 (m, 2 H),
3
2.23−2.31 (m, 2 H), 5.16−5.24 (m, 1 H), 7.45 (t, J = 7.9 Hz, 1 H),
7.61 (d, 3J = 8.0 Hz, 2 H), 7.81 (d, 3J = 8.1 Hz, 1 H), 8.00 (d, 3J = 8.0
3
3
Hz, 1 H), 8.02 (d, J = 8.3 Hz, 1 H), 8.08 (d, J = 8.0 Hz, 1 H), 8.09
(d, J = 8.3 Hz, 1 H), 8.41 ppm (m br, 2 H). 13C NMR (150 MHz,
3
CDCl3, 25 °C): δ = 14.0, 22.6, 27.1, 27.2, 29.3, 31.8, 32.4, 32.6, 118.7,
123.9, 127.4, 127.5, 129.2, 129.7, 129.8, 131.7 ppm. UV/vis (CHCl3):
λmax (ε) = 357.4 (6400), 376.4 (8300), 417.6 (11800), 438.2 (14600),
491.4 (12900), 526.6 (34000), 564.0 nm (47800). Fluorescence
(CHCl3, λmax = 526.6 nm): λmax (Irel) = 581.8 (1.00), 633.0 (0.58),
692.6 nm (0.12). Fluorescence quantum yield (λexc = 525.0 nm,
E525.0 nm/1 cm = 0.01681, CHCl3, reference 9a with Φ = 1.00): 0.96. MS
(DEI+, 70 eV): m/z (%): 700.2 (46.6), 699.2 (81.7) [M+ + 2H], 698.2
(49.3) [M+ + H], 697.2 (100) [M+], 619.3 (12.2), 519.0 (18.4) 516.0
(59.9), 438.1 (14.7), 437.1 (24.7), 56.9 (14.1), 54.9 (24.9), 43.1
(20.1), 41.2 (16.6). HRMS (DEI+, C42H40BrN3O2): Calcd m/z:
697.2304, found m/z: 697.2308, Δ = +0.0004. C42H40BrN3O2 (679.2):
Calcd C 72.20, H 5.77, N 6.01; found C 71.95, H 5.76, N 6.03.
14: 13 (100 mg, 0.143 mmol) in a heat-degassed Schlenk vessel was
flushed with argon, dissolved in warm toluene (8 mL), heated to
70 °C, and treated with tetrabutyl ammonium bromide (81.2 mg,
0.252 mmol) and Pd(OAc)2(24.7 mg, 0.110 mmol). The mixture was
heated at 100 °C, treated with triethylamine (1 mL), heated at 120 °C
for 15 h, allowed to cool, treated with 2 M aqueous HCl (100 mL),
and extracted with chloroform. The organic phase was dried with
MgSO4 and the reaction product purified by column separation (silica
gel, chloroform). Yield: 53.1 mg (60.0%) of a violet solid, mp >250 °C.
̃
Rf (silica gel, chloroform): 0.70. IR (ATR): ν = 3413.9 (w), 2953.8 (m),
2924.7 (vs), 2854.0 (s), 2359.9 (w), 2339.3 (w), 2097.0 (w), 1734.3
(w), 1718.5 (w), 1683.9 (s), 1637.9 (vs), 1622.4 (vs), 1606.5 (s),
1562.4 (m), 1535.2 (w), 1486.8 (w), 1455.0 (m), 1408.0 (w), 1408.0
(w), 1375.5 (w), 1344.1 (vs), 1294.2 (w), 1256.7 (w), 1224.8 (w),
1207.0 (w), 1120.5 (w), 1053.8 (w), 1024.6 (w), 947.3 (w), 811.9 (w),
16: N-(1-Hexylheptyl)-9-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)-3,4-perylenedicarboximide (15, 164 mg, 0.260 mmol) and 13 (200
mg, 0.286 mmol) were added to freshly distilled toluene (20 mL) with
the exclusion of air (argon atmosphere), treated with 1 M aqueous
Na2CO3 (16 mL) and ethanol (2 mL), heated at 80 °C, and treated
with Pd(PPh3)4 (34.6 mg, 0.03 mmol). The mixture was stirred at
80 °C for 16 h and allowed to cool to room temperature. The organic
phase was separated, dried with MgSO4, and purified by column
separation (silica gel, toluene). Yield: 53.1 mg (60.0%) of a violet solid,
mp >250 °C. Rf (silca gel/chloroform): 0.72. IR (ATR): ν = 3410.8
(w), 2951.6 (w), 2923.0 (m), 2854.2 (w), 1690.4 (s), 1651.8 (s),
1638.6 (vs), 1605.7 (s), 1591.8 (s), 1571.2 (s), 1534.4 (w), 1485.9
(w), 1453.8 (m), 1408.2 (m), 1374.3 (w), 1346.3 (vs), 1324.3 (s),
1291.5 (m), 1246.0 (s), 1208.1 (m), 1171.6 (m), 1106.8 (w), 1053.3
(w), 955.2 (w), 917.6 (w), 843.0 (m), 811.9 (vs), 777.7 (w), 757.4 (s),
723.0 (w), 687.1 cm−1 (m). 1H NMR (600 MHz, CDCl3, 25 °C): δ =
0.83 (t, 12 H, 3J(H,H) = 6.9 Hz, 12 H), 1.19−1.40 (m, 32 H), 1.83−
1.97 (m, 4 H), 2.25−2.38 (m, 4 H), 5.18−5.35 (m, 2 H), 7.46−
7.58 (m, 2 H.), 7.60−7.63 (m, 3 H), 7.65−7.80 (m, 4 H), 7.87 (d,
3J(H,H) = 7.7 Hz, 1 H),. 8.22−8.37 (m, 2 H), 8.45−8.50 (m, 2 H),
8.50−8.57 (m, 2 H), 8.58−8.70 (m, 4 H), 10.78−10.84 (m, 1 H),
11.52−11.60 ppm (m, 1 H). 13C NMR (150 MHz, CDCl3, 25 °C):
δ = 14.0, 22.6, 25.7, 27.0, 29.3, 31.8, 52.0, 54.4, 118.5, 120.0,
120.3, 122.0, 122.2, 123.7, 123.8, 124.0, 126.0, 126.1, 127.0,
127.9, 128.2, 130.1, 131.7, 147.6 ppm. UV/vis (CHCl3): λmax (ε) =
358.2 (12400), 378.0 (16800), 415.4 (20600), 436.4 (25300),
1
796.8 (w), 758.2 (w), 685.7 (w) cm−1. H NMR (600 MHz, CDCl3,
3
25 °C): δ = 0.84 (t, J = 7.0 Hz, 6 H), 1.20−1.48 (m, 16 H), 1.88−
2.00 (m, 2 H), 2.28−2.40 (m, 2 H), 5.21−5.34 (m, 1 H), 7.58 (t, 3J =
3
3
7.8 Hz, 2 H), 7.85 (d, J = 8.0 Hz, 2 H), 8.32 (d, J = 8.1 Hz, 2 H),
8.35 (d, 3J = 7.4 Hz, 2 H), 8.50 (br, 2 H).10.54 (d, 3J(H,H) = 7.6 Hz, 1
H), 11.46 ppm (s, 1 H). 13C NMR (150 MHz, CDCl3, 25 °C): δ =
14.0, 22.6, 27.1, 27.2, 29.3, 29.7, 31.8, 32.4, 32.6, 118.3, 123.5, 123.8,
126.4, 127.3, 127.4, 128.2, 128.7, 129.2, 129.5, 130.5, 130.8, 131.5,
133.7 ppm. UV/vis (CHCl3): λmax (ε) = 358.2 (12400), 378.0
(16800), 415.4 (20600), 436.4 (25300), 545.2 (51300), 586.0 nm
(10300). Fluorescence (CHCl3, λmax = 525.0 nm): λmax (Irel) = 581.8
(1.00), 633.0 (0.58), 692.6 nm (0.12). Fluorescence quantum yield
(λexc = 525.0 nm, E525.0 nm/1 cm = 0.01681, CHCl3, reference 9a with
Φ = 1.00): 0.96. MS (DEI+, 70 eV): m/z (%): 620.3 (32.8) [M+ + H],
619.3 (69.1) [M+], 438.1 (52.6), 437.1 (100), 322.1 (13.0), 321.1
(30.7). HRMS (DEI+, C42H41N3O2): Calcd m/z: 619.3199, found
m/z: 619.3185, Δ = −0.0014. C84H80N6O4 (1236.6): Calcd C 81.52,
H 6.79, N 6.52; found C 81.34, H 6.72, N 6.75.
15: N-(1-Hexylheptyl)-9-bromo-3,4-perylenedicarboximide (4, 770
mg, 1.32 mmol), bispinacolatodiborane (369 mg, 1.45 mmol), and
potassium acetate (376 mg, 3.83 mmol) were dissolved in 1,4-dioxane
(15 mL) with the exclusion of moisture and air (argon atmosphere)
and treated with PdCl2(dppf) (29.0 mg, 0.040 mmol). The mixture
was heated at 70 °C for 17 h and evaporated in vacuo. The residue was
purified by column separation (silica gel, chloroform). Yield: 524 mg
(63%) of an orange solid, mp >179−181 °C. Rf (silica gel/
545.2 (51300), 586.0 nm (10300). Fluorescence (CHCl3, λmax
=
545.2 nm): λmax (Irel) = 661.6 (1.00), 732.0 nm (0.49). Fluores-
cence quantum yield (λexc = 545.2 nm, E545.2 nm/1 cm = 0.0115,
CHCl3, reference 9a with Φ = 1.00): ca. 0.65. MS (FAB+): m/z (%):
1121.4 (8) [M+ + H], 1120.4 (6) [M+]. HRMS (FAB+, C77H76N4O4):
Calcd m/z: 1120.5867, found m/z: 1120.5924, Δ = +0.0057.
C77H76N4O4 (1120.6): Calcd C 82.47, H 6.83, N 5.00; found C
82.62, H 6.91, N 4.66.
̃
chloroform): 0.79. IR (ATR): ν = 2953.4 (m), 2924.3 (m), 2855.6
(m), 1689.6 (s), 1650.4 (vs), 1616.1 (w), 1591.5 (s), 1577.0 (m),
1523.0 (w), 1507.8 (m), 1459.5 (m), 1411.4 (m), 1377.6 (m), 1351.3
(s), 1328.3 (vs), 1293.0 (m), 1272.5 (m), 1245.6 (m), 1207.1 (m),
1170.3 (m), 1137.1 (s), 1114.6 (s), 1068.0 (m), 1051.1 (m), 966.6
(m), 934.5 (w), 900.1 (w), 858.9 (m), 840.2 (m), 809.1 (s), 764.3
(m), 751.0 (s), 724.7 (w), 713.5 (w), 700.0 (m), 681.8 (m), 666.6 (w),
ASSOCIATED CONTENT
* Supporting Information
Spectroscopic data of 8 and 10. This material is available free of
■
S
1
657.4 (w), 619.2 (w), 608.1 cm−1 (w). H NMR (600 MHz, CDCl3,
3
25 °C): δ = 0.81 (t, J(H,H) = 7.1 Hz, 6 H), 1.15−1.36 (m, 16 H),
charge via the Internet at http://pubs.acs.org.
G
dx.doi.org/10.1021/jo301417p | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
(13) (a) Quante, H.; Mullen, K. Angew. Chem. 1995, 107, 1487−
̈
AUTHOR INFORMATION
■
1489; Angew. Chem., Int. Ed. 1995, 34, 1323−1325. (b) Langhals, H.;
Corresponding Author
*E-mail: Langhals@lrz.uni-muenchen.de.
Sußmeier, F. J. Prakt. Chem. 1999, 341, 309−311.
̈
(14) Kinzel, S. Ph.D. thesis, Univ. Munich, 2010.
(15) (a) Langhals, H.; Hofer, A. Ger. Offen. DE 102012002678.1,
Feb 9, 2012. (b) Langhals, H.; von Unold, P.; Speckbacher, M. Liebigs
Ann./Recueil 1997, 467−468.
Notes
The authors declare no competing financial interest.
(16) Langhals, H.; Jona, W. Angew. Chem. 1998, 110, 998−1001;
Angew. Chem., Int. Ed. 1998, 37, 952−955.
(17) Langhals, H. Nachr. Chem., Tech. Lab. 1980, 28, 716−718;
Chem. Abstr. 1981, 95, R9816q.
ACKNOWLEDGMENTS
■
Financial support by the Fonds der Chemischen Industrie and
the CIPSM cluster Munich Center for Integrated Protein
Science is gratefully acknowledged. We thank Mr. Patrick Kolle
̈
for help with the quantum chemical calculations.
REFERENCES
■
(1) See for example: (a) Zollinger, H. Color Chemistry. Syntheses,
Properties and Applications of Organic Dyes and Pigments, 2nd ed.;
Weinheim, 1991; ISBN 3-527-28352-8. (b) Wolfbeis, O. S.
Fluorescence Spectroscopy, Methods and Applications; Springer Verlag:
Berlin, 1993.
(2) (a) Drexhage, K. H. Topics Appl. Phys. 1973, 1, 144−193.
(b) Shankarling, G. S.; Jarag, K. J. Resonance 2010, 15, 804−818;
Chem. Abstr. 2010, 153, 582539. (c) Luk’yanetz, E. A. Mol. Cryst.
Liquid Cryst. Sci. Technol., Sect. C 1992, 1, 15−28; Chem. Abstr. 1992,
117, 57729.
(3) (a) Langhals, H. Nachr. Chem., Tech. Lab. 1980, 28, 716−718;
Chem. Abstr. 1981, 95, R9816q. (b) Cole, T.; Zewail, A. H. Photochem.
Photobiol., Proc. Int. Conf. 1983, 2, 743−757; Chem. Abstr. 1985, 102,
48632.
(4) See for example: Langhals, H. Dyes for Fluorescent
Immunoassays. In Immunochemical Detection of Pesticides and their
Metabolites in the Water Cycle; Hock, B., Ed.; VCH Verlagsgesellschaft:
Weinheim, 1995; ISBN 3-527-27137-6; Chem. Abstr. 1996, 124,
24966z.
(5) Reviews: (a) Langhals, H. Helv. Chim. Acta 2005, 88, 1309−
1343. (b) Langhals, H. Heterocycles 1995, 40, 477−500.
(6) (a) Wurthner, F. Chem. Commun. 2004, 1564−1579. (b) Ilhan, F.
̈
D.; Tyson, S.; Stasko, D. J.; Kirschbaum, K.; Meador, M. A. J. Am.
Chem. Soc. 2006, 128, 702−703. (c) Vajiravelu, S.; Ramunas, L.; Vidas,
G. J.; Valentas, G.; Vygintas, J.; Valiyaveettil, S. J. Mater. Chem. 2009,
́
19, 4268−4275. (d) Fortage, J.; Severac, M.; Houarner-Rassin, C.;
Pellegrin, Y.; Blart, E.; Odobel, F. J. Photochem. Photobiol., A 2008, 197,
156−169. (e) Lukas, A. S.; Zhao, Y.; Miller, S. E.; Wasielewski, M. R. J.
Phys. Chem. B 2002, 106, 1299−1306. (f) Wurthner, F.; Sautter, A.;
̈
Schmid, D.; Weber, P. J. A. Chem.Eur. J. 2001, 7, 894−902.
(g) Ford, W. E.; Hiratsuka, H.; Kamat, P. V. J. Phys. Chem. 1989, 93,
6692−6696. (h) Zhan, X.; Facchetti, A.; Barlow, S.; Marks, T. J.;
Ratner, M. A.; Wasielewski, M. R.; Marder, S. R. Materials 2011, 23,
268−284. (i) Soh, N.; Ueda, T. Talanta 2011, 85, 1233−1237.
(j) Usta, H.; Facchetti, A.; Marks, T. J. Acc. Chem. Res. 2011, 44, 501−
510. (k) Zhan, X.; Facchetti, A.; Barlow, S.; Marks, T. J.; Ratner, M. A.;
Wasielewski, M R.; Marder, S. R. Adv. Mater. 2011, 23, 268−284.
(l) Metzger, R. M. Anal. Chim. Acta 2006, 568, 146−155. (m) Greene,
M. High Perform. Pigm. 2002, 249−261.
(7) Langhals, H.; Karolin, J.; Johansson, L. B.-Å. J. Chem. Soc.,
Faraday Trans. 1998, 94, 2919−2922.
(8) (a) Xerox Corp. Japan Pat. 03024059 A2, Feb 1, 1991; Chem.
Abstr. 1991, 115, 123841a. (b) Langhals, H.; Demmig, S. Ger. Offen.
DE 4007618.0, Mar 10, 1990; Chem. Abstr. 1992, 116, P117172n.
(9) Kaiser, H.; Lindner, J.; Langhals, H. Chem. Ber. 1991, 124, 529−
535.
(10) (a) Langhals, H.; Demmig, S.; Potrawa, T. J. Prakt. Chem. 1991,
333, 733−748. (b) Demmig, S.; Langhals, H. Chem. Ber. 1988, 121,
225−230.
(11) Sußmeier, F.; Langhals, H. Eur. J. Org. Chem. 2001, 607−610.
̈
(12) Feiler, L.; Langhals, H.; Polborn, K. Liebigs Ann. Chem. 1995,
1229−1244.
H
dx.doi.org/10.1021/jo301417p | J. Org. Chem. XXXX, XXX, XXX−XXX