The synthesis and characterisation of a free-base porphyrin-perylene dyad that exhibits electronic coupling in both the ground and excited states

Article abstract of DOI:10.1002/chem.200801779

A covalent dyad composed of a free-base porphyrin and a perylene diimide (1) was synthesised and characterised by NMR, HRMS, UV/Vis and fluorometric methods. UV/Vis spectrophotometric analysis indicated a moderate coupling between the components in the gr

Full text of DOI:10.1002/chem.200801779

DOI: 10.1002/chem.200801779
The Synthesis and Characterisation of a Free-Base Porphyrin–Perylene Dyad
that Exhibits Electronic Coupling in Both the Ground and Excited States
Simon Mathew and Martin R. Johnston*[a]
Abstract: A covalent dyad composed of a free-base porphyrin and a perylene di-
ACHTUNGTRENNUNGimide (1) was synthesised and characterised by NMR, HRMS, UV/Vis and fluoro-
metric methods. UV/Vis spectrophotometric analysis indicated a moderate cou-
pling between the components in the ground state. Fluorescence spectroscopy re-
vealed that the emissive properties of the dyad showed that the quantum yield of
emission from the porphyrin Soret band increased dramatically and could not be
rationalised by a straightforward photoinduced energy (and/or electron) transfer,
but rather a coupling of excited states.
Keywords: dyes/pigments · energy
conversion · fluorescence · porphy-
AHCTUNGTERGrNNUN inoids · UV/Vis spectroscopy
Introduction
performed on porphyrin–perylene dyads formed through al-
kynyl linkages between the two chromophores.[7–9] These
particular modes of connections between chromophores in
previously reported dyads caused the arrays to behave as a
supposition of the individual dye molecules, as observed
through absorption spectroscopy. Recently, we have synthes-
ised and characterised a dyad composed of a free-base por-
phyrin and a perylene diimide, in which the two components
are connected covalently through a methylene amide spacer,
pictured in Figure 1. The presence of the methylene spacer
in this dyad is a unique aspect and it is this particular fea-
ture as that extends unorthodox spectroscopic properties to
this molecule.
The utility of the perylene chromophore in dyad 1 is two-
fold in this construct. Firstly, the presence of the 3,5-di-tert-
butylphenoxy groups increases the solubility of the dyad.
This is important as both porphyrin and perylene diimide
molecules with low substitution are notorious for possessing
low solubilities in organic solvents, as a result of cofacial ag-
gregation.[10,11] Secondly, the high fluorescence quantum
yield associated with the perylene diimide family of mole-
cules ensures that photoinduced events initiated by the sin-
glet state of the perylene should correspondingly occur with
high quantum efficiency.[12]
The study of covalent and noncovalent photoactive dyads
and triads continues to be of interest due to the structural
and functional similarities these constructs share with the re-
action centre within the photosystem of purple photosyn-
thetic bacteria.[1,2] These particular constructs have been
studied due to their ability to donate and accept electrons
upon the absorption of light and it is this ability that has po-
tential applications in the field of solar-energy conver-
sion.[3,4]
We have recently embarked on a study of multichromo-
phoric arrays in the hope that these constructs will be utilis-
ed to realise artificial photosynthetic devices. As part of our
investigation toward the synthesis of multichromophoric
supramolecular triads and ternary systems, we have synthes-
ised a covalently bound dyad composed of a free-base por-
phyrin and a tetraarylperylene diimide.
Free-base porphyrin–perylene dyads have featured in pre-
vious studies with the majority of reports utilising an imide-
type connection between the chromophores, facilitated by
the reaction of an amino-functionalised porphyrin and a per-
ylene anhydride.[5,6] Comprehensive studies have also been
[a] Dr. S. Mathew, Dr. M. R. Johnston
School of Chemistry, Physics and Earth Sciences
Flinders University, GPO Box 2100
Adelaide SA 5001 (Australia)
Results and Discussion
Fax : (+618)8201-2905
E-mail: martin.johnston@flinders.edu.au
Synthesis of the free-base porphyrin perylene dyad 1: The
synthesis of 1 was performed by the coupling of respective
porphyrin (5) and perylene (10) units, the syntheses of
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200801779.
248
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Chem. Eur. J. 2009, 15, 248 – 253

FULL PAPER
Perylene fragment 10 was synthesised over four steps,
shown in Scheme 2, from the commercially available
1,6,7,12-tetrachloro-3,4:9,10-perylene dianhydride (6). For-
mation of the corresponding cyclohexyl diimide 7, was fol-
lowed by substitution of the halogen substituents of the per-
ylene core by 3,5-di-tert-butylphenol/K2CO3 in 1-methyl-2-
pyrrolidone (NMP), affording the highly soluble tetraaryl-
perylene diimide 8.[14] Anhydride 9 was formed by heating 8
in a solution of KOH in tert-BuOH/H2O. The desired pery-
lene fragment 10 was synthesised by the imidation reaction
of 9 by treatment with ammonium propionate in propionic
acid at reflux.
The synthesis of dyad 1 was achieved by a nucleophilic
substitution reaction between porphyrin 5 and the dianion
of 10, which was generated in situ by heating in NMP/
K2CO3 as outlined in Scheme 3. Slow addition of a solution
of 5 in NMP and monitoring of the reaction by TLC ensured
a reasonable yield (56%) of dyad 1. The identity of 1 was
1
confirmed by H and 13C NMR spectroscopy and high-reso-
lution ESI-MS. Characterisation by UV/Vis and fluores-
cence spectroscopic methods were also performed and are
discussed in the following section.
Spectrophotometric characterisation of dyad 1
Figure 1. The schematic (top) and an AM1 optimised geometry (below)
of the free-base porphyrin–perylene dyad 1.
UV/Vis spectrophotometric analysis of dyad 1: The UV/Vis
spectrum of 1, along with that of porphyrin reference 2 and
perylene reference 8, are shown in Figure 2 and summarised
in Table 1. The absorption spectrum of 1 possesses a porphy-
rin-derived Soret band at 420 nm and Q-bands at 519, 549
and 647 nm. A perylene-derived maximum at 590 nm is also
apparent in the UV/Vis spectrum of 1. The Soret absorption
in porphyrin reference 2 ap-
which are shown in Schemes 1 and 2. Porphyrin fragment 5
was synthesised by the regioselective mononitration and re-
duction of the tetraphenyl porphyrin 2.[13] This was followed
by the acylation of 4 with chloroacetyl chloride, as shown in
Scheme 1.
pears at 418 nm and exhibits a
molar
absorptivity
of
490000mÀ1 cmÀ1. Incorporation
of a free-base porphyrin into
dyad 1 causes red-shifting of
the Soret band by 2 nm and a
decrease of molar absorptivity
to a value of 285000mÀ1 cmÀ1.
In a similar manner, the Q-
band of 2 at 650 nm exhibits a
molar
absorptivity
of
5000mÀ1 cmÀ1 with the corre-
sponding peak in the dyad ex-
perienced a blue shift of 3 nm
and a decrease of molar absorp-
tivity to 3000mÀ1 cmÀ1. Perylene
reference 8 exhibits a maximum
at 582 nm, but comparisons of
molar absorptivities cannot be
made due to an overlapping Q-
band in the UV/Vis spectrum
of 1.
Scheme 1. The synthesis of porphyrin fragment 5. Reaction conditions: i) propionic acid, reflux, 17%;
ii) NaNO2, trifluoroacetic acid, 258C, 94%; iii) SnCl2·2H2O, conc. HCl(aq), 808C, 27%; iv) 2-chloroacetyl chlo-
ride, CH2Cl2, Et3N, 25 8C, 97%.
The reductions in the molar
absorptivities of the absorption
Chem. Eur. J. 2009, 15, 248 – 253
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www.chemeurj.org
249

M. R. Johnston and S. Mathew
Scheme 2. The synthesis of the perylene component 10. Reaction conditions: i) cyclohexylamine, H2O, reflux, 81%; ii) 3,5-di-tert-butylphenol, K2CO3,
NMP, 1208C, 83%; iii) KOH, H2O, tert-BuOH, 98%; iv) NH3(g), propionic acid, reflux, 87%.
bands in the UV/Vis spectra of
dyad 1 and reference 2 are con-
sistent with the presence of a
ground-state interaction be-
tween electroactive components
within the dyad.[15] The width of
the Soret band was analysed to
further clarify the nature of the
coupling. Events leading to ag-
gregation can be identified by
changes in the width and mag-
nitude of the Soret absorption
relative to 2.[16,17] As depicted
in Figure 2, the Soret band of 1
Scheme 3. The synthesis of dyad 1. Reaction conditions: i) K2CO3, NaI, NMP, 808C, 56%.
exhibits no broadening behav-
iour, suggesting that the por-
phyrinic component exists in
the monomeric form. Thus, it was concluded that the nature
of the observed moderate coupling is a product of coupling
between the porphyrin and perylene components of the
dyad in the ground state.[18]
Steady-state fluorometric analysis of dyad 1: The steady-state
emission spectra of 1, along with reference compounds 2
and 8 are presented in Figure 3 as well as Table 1. Excitation
of solutions of the compounds in toluene at 585 nm allowed
near-selective excitation (Abs2/Abs1 12:1) of the perylene
component within the dyad. Excitation of 1 at 585 nm re-
sulted in a fluorescence spectrum with the maxima at 615
and 650 nm reminiscent of a perylene diimide. The slight
shoulder at 720 nm in the emission spectrum of the dyad
was assigned to emission from
Figure 2. UV/Vis spectrum of 1 (black), 2 (dark grey), 8 (light grey) in
toluene and enlargement of S1 state transitions (inset).
the free-base porphyrin within
Table 1. Absorbance and emission maxima with respective molar absorptivities and emission origins.
1. The perylene-derived fluores-
cence from experienced
1
2
3
1
l [nm]
e [mcmÀ1
]
l [nm]
e [mcmÀ1
]
l [nm]
e [mcmÀ1
]
quenching when compared to
an optically matched solution
of perylene reference com-
pound 8. Reference 8 produced
an emission maximum at
606 nm, indicating that forma-
tion of the dyad was accompa-
absorbance
maxima
420
519
549
590
647
615
660
276000
25100
37400
56500
3000
418
514
549
592
650
653
719
490000
21200
8700
5800
4800
444
539
582
4500
27000
48000
emission
maxima
pery-type
porph-type
porph-type
porph-type
606
pery-type
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Chem. Eur. J. 2009, 15, 248 – 253

Porphyrin–Perylene Dyad
FULL PAPER
Figure 4. Excitation spectrum of 1 (black), 2 (dark grey) and 8 (light
grey) in toluene (lem =715 nm).
Figure 3. Emission spectrum of 1 (black, inset), 2 (dark grey, inset) and 8
(light grey) in toluene (lem =585 nm) and enlargement of 1 and 2 (inset).
nied by a 9 nm red-shift in emission maximum. The emission
greater contribution to the porphyrin-derived emission at
715 nm than 2, albeit the Soret absorption of 1 has a low-
ered molar absorptivity as ascertained from UV/Vis experi-
ments. The contribution of the Soret band of 1 is in fact
much larger than the additive contributions of 2 and 8 at
428 nm in producing emission at 715 nm. The excitation
spectrum of the perylene reference 8 exhibits a maximum at
583 nm, correlating well to the perylene excitation maxi-
mum of 1 at 589 nm. In a similar fashion to the correspond-
ing absorbance in the UV/Vis spectrum, formation of the
dyad resulted in red-shifting of this perylene excitation max-
imum.
The observations from the excitation experiments indicate
that dyad 1 emits with an enhanced quantum yield of fluo-
rescence relative to 2. The ground- and excited-state cou-
plings between the components in 1 observed in the UV/Vis
and fluorescence emission spectra allow the blending of
emission properties to occur. As a result of the enhanced
electronic interaction between the chromophores, the por-
phyrin component in 1 has adopted the high quantum yield
characteristics of the perylene component at the porphyrinic
Soret absorbance maximum.
The photoinduced behaviour of 1 is complex in nature,
but explainable by the lowest lying excited state characteris-
tics of the dyad being unified into a new single-quantum
system. The changes in emission intensity in Figure 4 are not
purely a product of photoinduced behaviour (photoinduced
electron or energy transfer) between the two components
within the dyad. A rationalisation of the degree of excitonic
coupling observed in dyad 1 is depicted in Figure 5. The dia-
gram shows two scenarios, one in which the coupling be-
tween components is strong and the compound behaves as a
new single-quantum system (left) with the energy delocal-
ised over the entire system. The other scenario depicted in
Figure 5 is the weak coupling regime in which the electroac-
tive components behave as separate entities (right), preserv-
ing their spectral properties and causing a photoinduced
energy transfer from a donor to an acceptor.[19] Although it
has been proven that the components of 1 couple in the ex-
cited state, the excited state dynamics of dyad 1 is a median
between these two depicted scenarios.
spectrum of porphyrin reference
2 exhibited emission
maxima at 653 and 719 nm. These maxima correlate well to
the features of the lower energy emissions of 1 at 650 nm
and the shoulder at 720 nm, respectively. The porphyrin-
type emission from 1 is significantly enhanced when com-
pared to the emission from an optically matched solution of
reference compound 2. The observation of fluorescence
quenching of the perylene component and the correspond-
ing enhancement of emission intensity from the porphyrin
component of the dyad is indicative of excited-state cou-
pling between the porphyrin and perylene components of
the dyad. Thus the electronic coupling between chromo-
phores identified in the UV/Vis spectrum of 1 is greater
than indicated by the absorption spectrum, as the coupling
regime extends into the excited state.
The blending of porphyrin and perylene excited states in
1 that yields an emission spectrum featuring the characteris-
tic emission maxima of both components is possible if the
observed porphyrinic emission intensity occurs at the ex-
pense of perylene emission intensity. The observation of de-
creased emission intensity from the perylene component of
1 is consistent with the occurrence of photoinduced energy
transfer within the dyad.
Evidence of the moderate level of excitonic coupling was
investigated further by obtaining excitation spectra by moni-
toring the emission intensity at 715 nm (corresponding to
the maximum lowest energy emission from tetraphenylpor-
phyrin) of 1, 2 and 8 as depicted in Figure 4. Figure 4 shows
that dyad 1 produced excitation maxima at 420, 551, 589
and 646 nm through reading the emission intensity at
715 nm. The peaks at 420, 551 and 646 nm clearly represent
a contribution from the porphyrin (Soret and Q-band) ab-
sorptions within 1 as presented in Figure 4. The excitation
spectrum of 2 possessed corresponding Soret and Q-band
maxima at 428, 547 and 648 nm. The greatest difference be-
tween the excitation spectra of 1 and 2 are their respective
emissions at 715 nm upon absorption of the Soret band. The
ratio of excitation energy (Em1:Em2) provided by the Soret
bands of 1 and 2 was calculated to be approximately 3:1.
Thus, absorption by the Soret band in 1 gave a threefold
Chem. Eur. J. 2009, 15, 248 – 253
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251

M. R. Johnston and S. Mathew
Experimental Section
1,6,7,12-Tetrachloro-3,4:9,10-perylene dianhydride (6) was purchased
from Synthon Chemicals (Wolfen, Germany) and used without further
purification. The remaining chemicals were purchased from Sigma–Al-
drich. Chemicals were purified as recommended by Perrin[22] and purified
solvents for chromatography were stored under 4ꢁ molecular sieves.
Thin-layer chromatography (TLC) was performed on pre-coated sheets
of Merck silica gel 60 and visualised using UV light (254 nm). Column
chromatography was carried out under a positive pressure of nitrogen
using Merck silica gel (230–400 mesh). NMR spectra were acquired on a
Varian Gemini 300 MHz spectrometer by using standard pulse sequences.
Spectra were recorded at 298 K in CDCl3 unless otherwise stated. Chemi-
cal shifts (d) are reported as parts per million (ppm) with respect to tet-
ramethylsilane (TMS) or CDCl3. Abbreviations used in assigning spectra
include: s, singlet; brs, broad singlet; d, doublet; t, triplet; q, quartet and
m, multiplet. The assignments observed in various NMR data were con-
firmed by homonuclear (1H-1H) correlation spectroscopy (COSY) and
heteronuclear (1H-13C) correlation spectroscopy (HETCOR) when re-
quired. HRMS acquired at Monash University (Melbourne, Australia) by
using electrospray ionisation (ESI-MS) or laser desorption ionisation
time-of-flight (LDI-ToF-MS) mass spectrometry. ESI-MS was performed
on a Micromass Quattro II Triple-Quadrupole mass spectrometer. LDI-
Figure 5. Depictions of the strong coupling regime (left) in which mole-
cules in a dyad behave as a single quantum system and weak coupling
(right) in which the molecules behave as separate entities (as observed
spectroscopically).[19]
The scenario between the two extreme cases in Figure 5
fits the photoinduced transitions observed in 1. In the
ground state of 1, a weak interaction between electroactive
centres of the dyad was established by UV/Vis spectroscopic
analysis, but the lack of a charge-transfer band indicated
that there was no significant electronic communication be-
tween the components. Upon absorption of light at 585 nm,
1 entered an excited state at which the moderate excitonic
interaction caused partial delocalisation of energy over the
whole system, resulting in diminished emission from the per-
ylene component. This quenching of emission intensity from
the perylene component within the dyad is likely to origi-
nate from the corresponding blending of emission proper-
ties. The quenching can be rationalised through the blending
of quantum yields for all the deactivation processes from
both of the components. That is, although the emission from
1 is predominantly derived from the perylene component,
the magnitude of the emission is dictated by a greater con-
tribution by internal conversion and intersystem crossing
contributions from the porphyrinic component of 1. Like-
wise, the threefold enhancement of Soret absorption in the
excitation spectrum of 1 (Figure 4) can be understood by
the delocalisation of excitation energy across the whole mol-
ecule. This particular mode of photoinduced behaviour is
highly unlikely if the dyad behaves as a superposition of the
individual components and this is not the case for 1. Similar
observations have been made for the aggregation of mole-
cules with the corresponding decrease in luminescence emis-
sion corresponding to increased phosphorescence.[20]
ToF-MS was performed on an Applied BioACHTUNTRGNEUNGsystems Voyager-DE STR Bi-
oSpectrometry Workstation. The instrument was operated in positive-ion
mode with the reflectron enabled for high-resolution analysis. Sample
was spotted on a stainless steel sample plate and allowed to air dry. Data
from 500 laser shots (337 nm nitrogen laser) were collected, signal aver-
aged and processed with the provided Data Explorer software. UV/Vis
experiments were performed at an ambient temperature of 258C by
using a Varian Cary 50 Scan Spectrophotometer. The samples were ana-
lysed in a Quartz cuvette obtained from Starna Pty. Steady-state fluores-
cence experiments were conducted on a Varian Cary Eclipse fluorescence
spectrophotometer equipped with a Varian single cell Peltier accessory
used in conjunction with a Gilson MINIPULS3 peristaltic pump to aid
temperature control of the sample. The samples were held in a quartz
cuvette obtained from Sigma-Aldrich and stirred with a magnetic flea.
Melting points were obtained on a Reichhart hot-stage apparatus and are
uncorrected. Calculations were performed on Spartanꢂ02 for Macintosh
by using the semi-empirical AM1 method.
5-(p-Chloroacetamidophenyl)-10,15,20-triphenylporphyrin (5): Com-
pound 4 (63 mg, 0.1 mmol) was dissolved in Et3N (1 mL) and CH2Cl2
(12.5 mL) under an atmosphere of nitrogen. Chloroacetyl chloride
(0.105 mmol, 8.4 mL) was added and the solution stirred for 1 h. Chloro-
AHCTUNGERTGaNNUN cetyl chloride (1.26 mmol, 100 mL) was added dropwise and the solution
stirred for a further 2 h. The solvent was evaporated and the crude prod-
uct subjected to column chromatography (silica, hexane then 1:2 EtOAc/
hexane then 1:1 EtOAc/hexane) to afford the desired product (69 mg,
97%) as a purple solid. M.p>3008C; 1H NMR (300 MHz, CDCl3, 258C,
TMS): d=À2.73 (brs, 2H; NH), 4.35 (s, 2H; CH2), 7.76–7.80 (m, 9H;
Ar-H), 7.95 (d, J=8.6 Hz, 2H; Ar-H), 8.22–8.28 (m, 8H; Ar-H), 8.58
(brs, 1H; NH), 8.90 ppm (s, 8H; b-H); 13C NMR (75 MHz, CDCl3, 258C,
TMS): d=43.01, 118.27, 119.08, 120.21, 120.26, 126.68, 127.72, 131.13,
134.53, 135.13, 136.40, 139.08, 142.08, 164.11 ppm; HRMS (ESI): m/z
calcd for C46H33ClN5O+ [M+H]+: 706.2368; found: 706.2366.
Conclusion
A free-base porphyrin–perylene dyad possessing a unique
methylene amide spacer has been synthesised and character-
ised. The spectroscopic properties of the dyad indicate the
presence of appreciable levels of electronic coupling be-
tween the chromophores in both ground and excited states.
Having studied the unusual spectrophotometric behaviour
of the dyad, corresponding studies of a hybrid covalent/
supramolecular triad can be performed utilising an appropri-
ate hydrogen-bonded electron acceptor.[21]
N,N’-Dicyclohexyl-1,6,7,12-tetrachloro-3,4:9,10-perylenediimide
(7):
Compound 6 (1 g, 2.0 mmol) and water (25 mL) were combined and,
with vigorous stirring, cyclohexylamine (5 mL, 4.34 g, 43 mmol) was
added dropwise. The resulting solution was heated to reflux for 10 h with
stirring. After cooling, the solution was diluted with water (100 mL) and
filtered onto a G4 sintered funnel. The solids were washed with water
(50 mL) and dried in an oven at 858C for 15 h to afford the product as
an orange solid (1.12 g, 81%). 1H NMR (300 MHz, CDCl3, 258C, TMS):
d=1.31–1.94 (m, 16H; CH2), 2.52 (m, 4H; CH2), 5.02 (t, J=12 Hz, 2H;
CH), 8.63 ppm (s, 4H; pery-H); 13C NMR (75 MHz, CDCl3, 258C, TMS):
d=25.32, 26.47, 29.03, 29.09, 54.46, 123.32, 123.77, 128.37, 131.39, 132.87,
135.28, 152.62, 162.63 ppm.
252
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Chem. Eur. J. 2009, 15, 248 – 253

Porphyrin–Perylene Dyad
FULL PAPER
N,N’-Dicyclohexyl-1,6,7,12-tetrakis(3,5-di-tert-butylphenoxy)-3,4:9,10-per-
ylenediimide (8): Compound 7 (1.2 g, 1.73 mmol), anhydrous K2CO3
(2.61 g, 18.9 mmol) and 3,5-di-tert-butylphenol (3.63 g, 17.4 mmol) were
combined in dry NMP (87 mL) under an inert atmosphere. The solution
was heated to 1208C for 48 h (endpoint by TLC silica, CHCl3). The solu-
tion was cooled and filtered through a G4 sintered funnel and the re-
maining solids stirred in water (200 mL). The product was filtered onto a
G4 sintered funnel, washed with water and dried in an oven at 858C
overnight to give the pure product (1.97 g, 83%). 1H NMR (300 MHz,
CDCl3, 258C, TMS): d=1.14 (s, 72H; CH3), 1.2–2.0 (m, 16H; CH2), 2.43
(m, 4H; CH2), 4.92 (m, 2H; CH), 6.82 (d, J=1.5 Hz, 8H; Ar-H), 7.14 (t,
J=1.5 Hz, 4H; Ar-H), 8.05 ppm (s, 4H; pery-H); 13C NMR (75 MHz,
CDCl3, 258C, TMS): d=25.40, 26.49, 29.08, 31.27, 34.82, 53.79, 115.12,
118.47, 119.00, 119.59, 112.77, 132.83, 152.78, 154.39, 156.79, 163.91 ppm;
UV/Vis (toluene): lmax(e)=582 (48000), 539 (27000), 444 nm
1.5 Hz, 2H; Ar-H), 7.68–7.78 (m, 9H; Ar-H), 7.87 (d, J=8.6 Hz, 2H; Ar-
H), 8.04 (brs, 1H; NH), 8.13 (d, J=8.6 Hz, 2H; Ar-H), 8.15 (s, 2H; pery-
H), 8.17–8.22 (m, 6H; Ar-H), 8.23 (s, 2H; pery-H), 8.54 (brs, 1H; NH),
8.82 (s, 4H; b-H), 8.84 ppm (s, 4H; b-H); 13C NMR (75 MHz, CDCl3,
258C, TMS): d=31.28, 31.30, 34.88, 34.90, 114.98, 115.13, 117.94, 118.50,
119.14, 119.28, 119.41, 120.10, 120.18, 126.63, 127.66, 130.99, 133.06,
133.30, 134.50, 135.00, 137.18, 138.18, 142.09, 152.91, 152.98, 154.19,
154.35, 156.76, 156.97, 163.15, 163.59, 165.35 ppm; UV/Vis (toluene):
lmax(e)=590
(57000),
549
(37000),
520
(26000),
420 nm
+
(284000 molÀ1 m3 cmÀ1); HRMS (ESI): m/z calcd for C126H122N7O9
[M+H]+: 1876.9299; found: 1876.9286.
+
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(14000molÀ1 m3 cmÀ1); HRMS (ESI): m/z calcd for C69H14NaO4
[M+Na]+: 1393.8151; found: 1393.8154.
1,6,7,12-Tetrakis(3,5-di-tert-butylphenoxy)-3,4:9,10-perylene dianhydride
(9): Compound
8 (0.892 g, 0.65 mmol) was added to tert-butanol
(52.7 mL), potassium hydroxide (5.27 g, 80 mmol) and water (2.6 mL)
and the resulting solution refluxed for 25 h. Hydrochloric acid (2n,
53 mL) was added to the cooled solution and stirring was continued for
6 h. The precipitate was filtered onto a G4 sintered funnel and washed
thoroughly with water then dried at 858C overnight to afford the anhy-
dride as a red powder (770 mg, 98%). 1H NMR (300 MHz, CDCl3, 258C,
TMS): d=1.15 (s, 72H; CH3), 6.81 (d, J=1.5 Hz, 8H; Ar-H), 7.19 (t, J=
1.5 Hz, 4H; Ar-H), 8.09 ppm (s, 4H; pery-H); 13C NMR (75 MHz,
CDCl3, 258C, TMS): d=31.24, 34.91, 114.93, 118.50, 119.62, 120.30,
120.79, 121.11, 133.51, 153.27, 154.01, 157.17, 159.94 ppm; HRMS (ESI):
+
m/z calcd for C81H93O11 [M+MeOH+H]+: 1241.6712; found: 1241.6720.
1,6,7,12-Tetrakis(3,5-di-tert-butylphenoxy)-3,4:9,10-perylene diimide (10):
Compound
9 (291 mg, 0.240 mmol) was dissolved in propionic acid
(15 mL) and anhydrous ammonia (2.01 g) was bubbled into the reaction.
After sustaining the mixture overnight at reflux, the solution was cooled,
hydrochloric acid (1n, 15 mL) was added and the mixture stirred for 8 h.
The solids were filtered onto a G4 sintered funnel, washed with water
and dried in an oven at 858C. The solids were dissolved in minimal
CH2Cl2 and separated by column chromatography (silica, 30% EtOAc/
CH2Cl2) to afford the desired product (251 mg, 87%) as a crimson solid.
1H NMR (300 MHz, CDCl3, 258C, TMS): d=1.15 (s, 72H; CH3), 6.81 (d,
J=1.8 Hz, 8H; Ar-H), 7.16 (t, J=1.8 Hz, 4H; Ar-H), 8.09 (s, 4H; pery-
H), 8.38 ppm (brs, 2H; NH); 13C NMR (75 MHz, CDCl3, 258C, TMS):
d=31.27, 34.88, 114.99, 118.42, 119.21, 120.25, 122.19, 152.96, 154.31,
[10] G. Seybold, G. Wagenblast, Dyes Pigm. 1989, 11, 303–317.
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[12] H. Langhals, W. Jona, Angew. Chem. 1998, 110, 998–1001; Angew.
Chem. Int. Ed. 1998, 37, 952–955.
[13] R. Luguya, L. Jaquinod, F. R. Fronczek, M. G. H. Vicente, K. M.
Smith, Tetrahedron 2004, 60, 2757–2763.
[14] D. Dotcheva, M. Klapper, K. Muellen, Macromol. Chem. Phys.
1994, 195, 1905–1911.
[15] G. Hungerford, M. Van Der Auweraer, D. B. Amabilino, J. Porphy-
AHCTUNGTRENNrGUN ins Phthalocyanines 2001, 5, 633–644.
[16] K. Prochꢄzkovꢄ, Z. Zelinger, K. Lang, P. Kubat, J. Phys. Org. Chem.
2004, 17, 890–897.
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5425.
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age, N. Solladie, New J. Chem. 1999, 23, 1151–1158.
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E. M. H. P. van Dijk, N. F. van Hulst, ChemPhysChem 2005, 6, 819–
827.
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[21] S. Mathew, M. R. Johnston, unpublished results.
[22] D. D. Perrin, W. L. F. Armarego, D. R. Perrin, Purification of Labo-
ratory Chemicals, Pergamon Press, Oxford, 1966, p. 370.
+
156.76, 163.05 ppm; HRMS (ESI): m/z calcd for C80H91N2O8 [M+H]+:
1207.6769; found: 1207.6766.
Free-base porphyrin–perylene dyad (1): Compound 10 (100 mg,
0.08 mmol) was dissolved in NMP (10 mL) with K2CO3 (100 mg,
0.72 mmol) and NaI (100 mg, 0.67 mmol) at 808C for 1 h under an inert
atmosphere. Compound 5 (51 mg, 0.07 mmol) in NMP (5 mL) added
dropwise over the course of 2 h. The reaction mixture was poured into
water (200 mL) and extracted with toluene (5ꢃ20 mL). The organic ex-
tracts were washed with water (5ꢃ100 mL) dried (Na2SO4) and solvent
evaporated. Chromatography (silica, hexane then 1:2 EtOAc/hexane then
1:1 EtOAc/hexane) afforded the product (73 mg, 56%) as a purple solid.
M.p.>3008C; 1H NMR (300 MHz, CDCl3, 258C, TMS): d=À2.80 (brs,
1H; NH), 1.17 (s, 36H; CH3), 1.19 (s, 36H; CH3), 5.00 (d, J=15 Hz, 1H;
CH2), 5.19 (d, J=15 Hz, 1H; CH2), 6.87 (d, J=1.5 Hz, 4H; Ar-H), 6.88
(d, J=1.5 Hz, A4H; r-H), 7.19 (t, J=1.5 Hz, 2H; Ar-H), 7.20 (t, J=
Received: August 29, 2008
Published online: November 19, 2008
Chem. Eur. J. 2009, 15, 248 – 253
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
253