Synthesis and Characterization of Dendritic Multichromophores Based on Rylene Dyes for Vectorial Transduction of Excitation Energy

Article abstract of DOI:10.1002/chem.200305359

The synthesis of dendritic multichromophores based on a rigid polyphenylene scaffold is presented. Different rylene chromophores are incorporated into the core, the branches, and the surface of the dendrimer. In this way, two generations of dendritic dyads consisting of a terrylenediimide core, a stiff polyphenylene scaffold, and a perylenemonoimide periphery were obtained. Furthermore, the first synthetic approach to a dendritic triad is introduced. The outer sphere of this macromolecule is formed by naphthalenemonoimide chromophores, whereas perylenemonoimide groups are located in the dendritic scaffold, and the terrylenediimide chromophore serves as a core molecule. This multichromophore absorbs over the whole range of the visible spectrum and shows well-separated absorption envelopes. In the course of dendrimer synthesis new attempts towards a straightforward functionalization strategy for rylene dyes are also presented.

Full text of DOI:10.1002/chem.200305359

FULL PAPER
Synthesis and Characterization of Dendritic Multichromophores Based on
Rylene Dyes for Vectorial Transduction of Excitation Energy
[a]
Tanja Weil,Erik Reuther,Cornelia Beer,and Klaus M¸llen*
Abstract: The synthesis of dendritic
multichromophores based on a rigid
polyphenylene scaffold is presented.
Different rylene chromophores are in-
corporated into the core, the branches,
and the surface of the dendrimer.In
this way, two generations of dendritic
dyads consisting of a terrylenediimide
core, a stiff polyphenylene scaffold,
and a perylenemonoimide periphery
were obtained.Furthermore, the first
synthetic approach to a dendritic triad
is introduced.The outer sphere of this
macromolecule is formed by naphtha-
lenemonoimide chromophores, whereas
perylenemonoimide groups are located
in the dendritic scaffold, and the terry-
lenediimide chromophore serves as a
core molecule.This multichromophore
absorbs over the whole range of the
visible spectrum and shows well-sepa-
rated absorption envelopes.In the
course of dendrimer synthesis new at-
tempts towards a straightforward func-
tionalization strategy for rylene dyes
are also presented.
Keywords: chromophores
¥
cycloaddition ¥ dendrimers ¥ energy
transfer ¥ rylene dyes
17]
20]
Introduction
Moore et al.,[15 Frÿchet et al.,[18 Aida et al.,[21] and Bal-
zani et al.[10a,b] Moore et al.reported phenylacetylene den-
drimers with a central perylene dye and a scaffold consisting
of ethynyl groups with different conjugation lengths.Most
of the other groups used an aryl ether scaffold introduced
by Frÿchet et al.[22,23] These dendrimers have been decorated
with two kinds of coumarin dyes or porphyrins.In all cases,
efficient energy transfer was observed,[24] and for the phenyl-
acetylene dendrimers an energy gradient from the periphery
towards the center has been proven.[16] However, the investi-
gation of chromophore interactions in these dendrimers is
often very complicated due to the flexible nature of the den-
dritic branches of most dendrimers and the low photostabili-
ty and fluorescence quantum yields of the chosen chromo-
phores.[24,25] Collective effects, quite well-known in biological
systems, have been demonstrated in rigid polyphenylene
dendrimers functionalized with very photostable perylene-
monoimide chromophores at the periphery, for which an in-
vestigation at the single-molecule level could be achieved.[26]
Here, we present a new approach towards the synthesis of
dendritic multichromophores in which the topology of the
chromophores within the dendrimer is well defined due to a
In recent years different attempts towards the synthesis of
3]
organic,[1 supramolecular,[4] polymeric,[5] and dendritic[6]
multichromophores have been reported.Among other rea-
sons, these molecules have been of special interest for the
investigation of interactions between chromophores and
have been considered to be promising model compounds for
multichromophore arrays and potential light-harvesting sys-
tems.In this context, the importance of dendrimers as
model compounds for biopolymers such as proteins has
been especially emphasized, which is due to their combina-
tion of high molecular weight and structural perfection
(monodispersity).[6] Furthermore, dendrimers can be grown
from a focal point and offer the unique possibility that func-
tional groups can be introduced at three different posi-
tions[7]: The center,[8] the scaffold,[4,9,10] and the periph-
ery.[11,12] This holds especially true for so-called rigid den-
drimers, in which the branches show no backfolding[13,14] and
the topology of the functionality is retained even in solution.
Important examples of dendritic multichromophores bearing
different types of chromophores have been reported by
polyphenylene scaffold which serves as a stiff matrix.Since
29]
rylene dyes survive a temperature of 2008C[27
and have
excellent photostability, high extinction coefficients, and a
fluorescence quantum yield of approximately one,[30] we
were able to design an outstanding multichromophoric array
by using a thermally and chemically stable polyphenylene
dendrimer.For the buildup of multichromophores in which
efficient energy transfer over long distances can take place,
[a] Dr.T.Weil, Dr.E.Reuther, C.Beer, Prof.Dr.K.M¸llen
Max-Planck-Institute for Polymer Research
Ackermannweg 10
55128 Mainz (Germany)
Fax : (+49)6131-379100
E-mail: muellen@mpip-mainz.mpg.de
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1398 1414
the optical properties of the individual chromophores and
their spatial arrangement are crucial.[31] Nature has brought
this principle to perfection, as can be seen from the crystal
structure of the light-harvesting antenna complex (LH2) of
the purple bacterium Rhodopseudomonas acidophila.[32] In a
photosynthetic system light is collected by the antenna
system and transferred to the reaction center.Therefore,
chromophores absorbing short wavelengths are located at
the outside and transfer their energy to longer-wavelength-
absorbing acceptor chromophores.In this way, energy trans-
fer is achieved over large distances.These very efficient sys-
tems inspired us to synthesize globular polyphenylene den-
drimers bearing a long-wavelength-absorbing terrylenedii-
mide (TDI) chromophore (Figure 1a) in the center and
shorter-wavelength-absorbing perylenemonoimide (PMI)
chromophores (Figure 1a) at the periphery.The spatial ar-
rangement of PMI chromophores at the periphery and a
TDI chromophore in the center was chosen with a view to
the formation of an energy gradient from the periphery to-
wards the center of the dendrimer.[35] The synthesis of a bi-
chromophore as well as a dendrimer allowing very efficient
energy transfer between perylene and terrylene chromo-
phores has already been demonstrated in the literature,
albeit based on a different structural concept to that pre-
sented here.[33,34]
Furthermore, the synthesis of the first dendritic triad con-
sisting of terrylenetetracarboxdiimide, perylenedicarboxmo-
noimide, and naphthalenedicarboxmonoimide (NMI, Fig-
ure 1a) chromophores is presented in detail.[35] Figure 1b
outlines the synthetic concept: A depicts a dendritic multi-
chromophore consisting of one type of chromophore (e.g.,
PMI), whereas B and C represent two molecular dyads with
increasing interchromophore distance, and D stands for an
NMI-PMI-TDI-containing molecular triad.To contribute to
the clarity of the molecular structure, the notation ™dyad∫
(Figure 1b, B and C) is used in the following for dendritic
multichromophores bearing two, and ™triad∫ for the respec-
tive multichromophores bearing three different types of
chromophores (Figure 1b, D).
Results and Discussion
We have already described the synthesis of polyphenylene
dendrimers decorated with PMI chromophores.[34,36] Fluores-
cent first-generation polyphenylene dendrimers (4,
Scheme 1) were obtained by Diels Alder cycloaddition of a
tetraphenylcyclopentadienone carrying one PMI chromo-
phore 2 with a tetrahedral core molecule 1 bearing free eth-
ynyl groups.This reaction proceeds at 170 8C in o-xylene
with extrusion of CO.For the convergent buildup of second-
generation polyphenylene den-
drimer 5 a functionalized poly-
phenylene dendrimer branch 3
(dendron) is required (Sche-
me 1).[34,37,40a]
Here we describe the spatial-
ly defined introduction of chro-
mophores into the center (Fig-
ure 2a), the scaffold (Fig-
ure 2b), and at the surface (Fig-
ure 2c) of the dendrimer.For
this purpose, the synthesis of a
chromophore core building
block and cyclopentadienone
branching
and
terminating
agents functionalized with dif-
ferent chromophores are cru-
cial.In our case, a core building
block bears more than one free
ethynyl group, and this allows
regular dendrimer growth by re-
action with cyclopentadienones
(Figure 2a).Branching agents
allow the introduction of func-
tionalities within the dendritic
scaffold and therefore bear at
least one ethynyl group as well
as the functional group, for ex-
ample,
a chromophore (Fig-
ure 2b, 12 in Figure 4), whereas
terminating agents are cyclo-
pentadienones lacking ethynyl
groups (Figure 2c).After cyclo-
Figure 1.a) Chemical structures of unsubstituted rylenediimide chromophores: naphthalenedicarboximide
(NMI), perylenedicarboximide (PMI), and terrylenetetracarboxdiimide (TDI); b) Sketch of the herein-report-
ed synthetic approach. A represents a multichromophore carrying PMI substituents at the surface; B and C
correspond to two molecular dyads, and D stands for an NMI-PMI-TDI triad.
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K.M¸llen et al.
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addition with a terminating re-
agent further dendritic growth
is no longer possible.
First, the synthesis of a TDI
core molecule bearing free eth-
ynyl groups is presented.This
synthetic approach requires the
introduction of bromine sub-
stituents in the so-called bay
region of the TDI chromophore
(Figure 1a), which has not been
described before.Furthermore,
tetraphenylcyclopentadienones
and polyphenylene dendrons
functionalized with PMI and
NMI dyes must be synthesized
which will serve as terminating
reagents for the introduction of
chromophores exclusively in
the outer sphere.Therefore, the
synthesis of a dendritic triad re-
quires
a
cyclopentadienone
branching agent bearing a chro-
mophore and a protected eth-
ynyl group.
Scheme 1.Schematic overview of Diels Alder cycloaddition of a tetraphenyltetraethynylmethane core 1 with
a tetraphenylcyclopentadienone building block 2 or a dendrimer branch 3 decorated with PMI chromophores
leading to first- and second-generation polyphenylene dendrimers 4 and 5, respectively.[34,40a]
Synthesis of the terrylenetetra-
carboxdiimide core: As core
molecule we chose a terrylene-
tetracarboxdiimide
chromo-
phore (TDI, 6) because its ab-
sorption maximum is located at
longer wavelength in the visible
spectrum.[38,39] The synthesis of
6 was first published by us,[38]
and a recent improvement to
this synthetic approach has
made larger quantities availa-
ble.[40b] However, the functional-
ization of 6 has not been descri-
bed before.Tetrabromoterryle-
netetracarboxdiimide chromo-
phore 7 was prepared by bromi-
nation of 6 with five equivalents
of bromine in boiling trichloro-
methane (Scheme 2).Monitor-
ing of the reaction by TLC or
FD mass spectrometry is indis-
pensable to avoid overbromina-
tion after extended reaction
times.Purification was achieved
by column chromatography
with trichloromethane as eluent
(Rf =0.9). Sometimes, a further
chromatographic step using tol-
uene was required (Rf =0.15)
which gave pure 7 as a blue
solid in 75% yield.The intro-
duction of substituents in the
Figure 2.Introduction of functional groups at different locations of a polyphenylene dendrimer: core molecule
(a), branching agent (b), and terminating agent (c).
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Dendritic Multichromophores
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Scheme 2.Introduction of functional groups into the bay region of the TDI chromophore 6.i) 5 equiv Br 2, chloroform, 75%; ii) 15 equiv 4-iodophenol
(18), 7.5 equiv K2CO3, N-methylpyrrolidone, 12 h, 908C, 55%; iii) 5 equiv triisopropylsilylacetylene, 0.4 equiv copper(i) iodide, 0.4 equiv PPh3, 0.2 equiv
[Pd(PPh2)Cl2], THF/triethylamine (3/1), 60%; iv) 1 equiv tetrabutylammonium fluoride, THF, 3 min, 91%.
bay region of TDI chromophore 6 reduces the planarity of
the aromatic terrylene chromophore and results in a signifi-
cantly higher solubility of 7 in organic solvents such as di-
chloromethane, toluene, and THF.Consequently, purifica-
tion and characterization are facilitated.In the next step, we
achieved complete exchange of the four bromine groups of
7 by 4-iodophenol (10 equiv) in moderate yields (55%).The
reaction proceeded with eight equivalents of K2CO3 in N-
methylpyrrolidone at 908C over 12 h.The crude mixture
was poured into 2n HCl, and a blue precipitate was formed.
After filtration the product mixture was washed twice with
water/dichloromethane and purified by column chromatog-
raphy with dichloromethane as eluent (Rf =0.86). Thus, 8
was obtained in 55% yield.
Compound 8 was treated with triisopropylsilylacetylene
(TiPS-acetylene) at room temperature over 20 h to give the
corresponding TDI chromophore 9 carrying four triisopro-
pylsilylethynyl groups in a procedure first reported by Sono-
gashira et al.[41] In some cases a mixture of tri- and tetrasub-
stituted derivatives was obtained even after extended reac-
tion times and with an excess of the acetylene component.
However, the byproduct could easily be separated by
column chromatography with dichloromethane/petroleum
ether (1/1, Rf(product)=0.95, Rf(by-product)=0.81), which
gave 9 in 60% yield.Cleavage of the four triisopropylsilyl
protecting groups of 9 with one equivalent of Bu4NF¥3H2O
was complete after 3 min in freshly distilled THF.There-
after, the reaction was quenched with water and washed
with water and dichloromethane.Longer reaction times led
to a drastically reduced yield of 10, and monitoring of
he reaction by TLC (dichloromethane) is therefore indis-
pensable.After column chromatography with dichloro-
methane the desired TDI core molecule 10 was obtained
in 91% yield as a dark blue solid.This core molecule
possesses four ethynyl groups which can be subjected
to Diels Alder cycloaddition with tetraphenylcyclopentadie-
nones to give a polyphenylene dendrimer with a TDI
core.
1
Figure 3 shows the H NMR spectrum of 10.The assign-
ment of the signals was based on H,H COSY and NOE ex-
periments.The singlet at 93.0 ppm with a relative intensity
of 4H corresponds to H-1 of the bay region of the TDI
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K.M¸llen et al.
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ly shifted relative to TDI.
Therefore, PMI chromophores
should be positioned in the
dendritic scaffold or at the pe-
riphery, where they can pass on
energy after excitation from the
surface toward the TDI center.
For the preparation of a den-
dritic triad, the NMI chromo-
phore, which absorbs and emits
at shorter wavelength than PMI
and TDI, must be located ex-
clusively at the periphery to
generate an energy gradient be-
tween the periphery and the
center.With regard to the char-
acteristic spectral features of
these chromophores, the follow-
ing chromophore-labeled cyclo-
pentadienone building blocks
are required for the synthesis of
dendritic dyads and triads
(Scheme 3):
none-based terminating agent
11 bearing a single PMI chro-
A cyclopentadie-
Figure 3.500 MHz 1H NMR spectrum of 10 in [D8]THF at 298 K.
mophore and a polyphenylene
chromophore, and the four protons located near the imide
structure H-2 are observed at 8.23 ppm.
dendron 14 carrying two PMI chromophores, which will
allow the synthesis of first- and second-generation dyads
with varying PMI TDI distances.
Synthesis of the dendritic scaffold: The PMI dye shown in
Figure 1a has absorption maxima which are hypsochromical-
The synthesis of a dendritic triad requires a branching
agent, namely, 12 bearing a PMI chromophore and an addi-
Scheme 3.Tetraphenylcyclopentadienone-based building blocks for introduction of chromophores into the dendritic scaffold and at the periphery. Com-
pound 11 serves as a terminating agent for introduction of PMI chromophores at the periphery, 12 is a building block for introduction of PMI chromo-
phores into the dendritic scaffold, and 13 and 14 are terminating building block for buildup of second-generation dendrimers bearing NMI or PMI chro-
mophores.
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Dendritic Multichromophores
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tional triisopropylsilyl-protected ethynyl unit which leads to
further dendrimer growth.The NMI-substituted dendron 13
can also serve as terminating agent.
has not been described before.We achieved the synthesis of
17 in six steps and high yield (Scheme 5).
1-Bromo-4-iodobenzene (18) underwent selective cou-
pling with trimethylsilylacetylene (TMS-acetylene) at room
temperature in toluene/triethylamine (1/3) according to a lit-
erature procedure.[46] Thereafter, Sonogashira coupling of 19
with TiPS-acetylene proceeded under the same reaction
conditions but at a temperature above 708C to give 20 in
95% yield.Compound 20 bears two different ethynyl pro-
tecting groups, whereby only the TMS group is sensitive to
caustic conditions.Thus, 20 could selectively be deprotected
by using 1m potassium hydroxide in THF, as already descri-
bed.[46] Compound 21 could be subjected to a further Sono-
gashira coupling with 1-bromo-4-iodobenzene to give diphe-
nylacetylene 22.After purification by column chromatogra-
phy with petroleum ether as eluent 22 was obtained as a col-
orless solid in 81% yield.The next reaction step involved
the oxidation of 22 with I2 in DMSO at 1908C over 12 h.
This reaction proceeded in high yield, whereupon benzil de-
rivative 23 was isolated as a bright yellow solid.The last
step was based on a Knoevenagel condensation of 23 with
1.1 equivalents of 1,3-diphenylacetone (24) and tetrabutyl-
amonium hydroxide in ethanol at 808C (15 min).[47] After
cooling, a dark precipitate was formed, which was collected
by filtration, washed with a small amount of cold ethanol,
and purified by column chromatography with dichlorome-
thane/petroleum ether (1/1) to give 17 as a dark purple solid
in 78% yield.A key feature is that the bromo substituent of
17 allows a wide variety of functional groups to be intro-
duced by palladium-catalyzed coupling with, for example,
boronic acid, as was shown above (Scheme 4).
An important compound for
The synthesis of cyclopentadienones and dendrons carry-
ing one PMI dye has already briefly been discussed in the
literature.[34] The key building block is the boronic ester of a
PMI chromophore (15), which is accessible by palladium-
catalyzed coupling of commercially available bispinacolato-
diboron and the corresponding bromo-substituted chromo-
phore[42] in a modification of the Suzuki procedure[43]
(Scheme 4).
This mild procedure particularly tolerates already existing
functional groups such as esters, ketones, and cyano or nitro
substituents, in contrast to conventional methods involving
lithiation reactions.The reaction proceeded in high yield in
dioxane and potassium acetate at 808C with exclusion of
light.In some cases homocoupling of two PMI chromo-
phores can occur.However, by-products were separated by
column chromatography with dichloromethane.Compound
15 was then treated with bromo-substituted tetraphenylcy-
clopentadienone 16 or 17 in a palladium-catalyzed coupling
reaction under Suzuki conditions[44,45] (Scheme 4).By using
a 1.5-fold excess of 15, catalytic amounts of [Pd(PPh3)4], and
caustic conditions (2n K2CO3) in a two-phase system (tolu-
ene/ethanol) at 858C, both 11 and 12 were obtained in a
single reaction step.Purification by column chromatography
with dichloromethane gave the cyclopentadienones 11 and
12 in 51 and 59% yield, respectively.A further chromatog-
raphy step with dichloromethane/petroleum ether (1.5/1)
was sometimes necessary to achieve sufficient purity.The
synthesis of a cyclopentadienone branching agent such as 17
the preparation of polypheny-
lene dendrons was 4,4’-diethy-
nylbenzil (25), whose synthesis
was previously published by
our group.[34,37] Compound 25
was treated with an excess of 3-
(4-bromophenyl)-2,4,5-triphen-
ylcyclopentadienone (16) in a
Diels Alder cycloaddition in
refluxing o-xylene (Scheme 6).
Hereby, benzil 26 was formed
as a pale yellow amorphous
powder in high yield (97%).
Purification was achieved by
column chromatography or
simple precipitation from meth-
anol.The latter method re-
duced the overall yield by
about 10%.Subsequent Knoe-
venagel condensation of 26
with 1,3-diphenylacetone (24)
in toluene in the presence of
tetrabutylammonium hydroxide
at 1008C (50 min) gave the cor-
responding dendron 27 in 63%
yield.
Scheme 4.Functionalization of cyclopentadienone building blocks with PMI chromophores. i) 08. equiv 17,
K2CO3, toluene/ethanol, 12 h, 808C, 59%; ii) 0.8 equiv 16, K2CO3, toluene/ethanol, 12 h, 808C, 51%.
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PMI-substituted dendron 14 in
o-xylene at 1708C over three
days.Compound 30 was puri-
fied by column chromatography
with acetone.After separation
of the starting material, 30 was
eluted with THF.Pure dyad 30
was obtained as a purple solid
in 83% yield.For the synthesis
of the triad 32 a multistep reac-
tion was necessary.First TDI
core 10 was treated with five
equivalents of PMI-labeled
branching agent 12 at 1708C
over 12 h.Thereafter, the crude
product was separated by
column chromatography with
dichloromethane to give 31a in
90% yield.Compound 31a has
nearly the same chemical struc-
ture as 29, the only difference
being four TiPS-protected eth-
ynyl groups at the periphery of
the dendrimer.These protecting
groups could be cleaved by ap-
plying one equivalent of tetra-
butylammonium fluoride in
THF.After four minutes, the
reaction was quenched by
adding water, and the whole re-
action mixture was washed with
water and dichloromethane.
Pure 31b was obtained in
nearly quantitative yield after
filtration through a short pad of
silica gel with dichloromethane
as solvent.This first-generation
polyphenylene dendrimer bear-
ing two different types of chro-
mophores can now undergo a
further reaction with dendron
Scheme 5.Synthesis of a building block for the introduction of functionalities into the dendritic scaffold.
i) 1.25 equiv trimethylsilylacetylene, 0.1 equiv triphenylphosphane, 0.1 equiv copper(i) iodide, 0.05 equiv
[PdCl2(PPh3)2] toluene/triethylamine (1/3), 12 h, RT, 89%; ii) 1.25 equiv triisopropylsilylacetylene, 0.1 equiv tri-
phenylphosphane, 0.1 equiv cooper(i) iodide, 0.05 equiv [PdCl2(PPh3)2], toluene/triethylamine (1/3), 12 h,
808C, 95%; iii) 2n potassium hydroxide, ethanol, 3 h, RT, 84%; iv) 1.25 equiv 4-bromoiodobenzene, 0.1 equiv
triphenylphosphane, 0.1 equiv cooper(i)iodide, 0.05 equiv [PdCl2(PPh3)2] catalyst, toluene/triethylamine (1/3),
12 h, RT, 81%; v) iodine, DMSO, 1908C, 12 h, 84%; vi) 1 equiv 24, tetrabutylammonium hydroxide, toluene,
15 min, 908C, 78%.
Scheme 6.Synthesis of a polyphenylene dendron carrying two bromo substituents.i) 3 equiv 16, o-xylene, 12 h,
1708C, 97%; ii) 1.1 equiv 24, tetrabutylammonium hydroxide, toluene, 50 min, 908C, 63%.
Finally, the introduction of the chromophore units was
achieved by Suzuki coupling of 27 and a 1.5-fold excess of
the appropriate chromophore 15 or 28 with catalytic
amounts of [Pd(PPh3)4] under caustic conditions (2n
K2CO3), as described before (Scheme 7).After column chro-
matography with dichloromethane the twofold PMI- and
NMI-substituted dendrons 13 and 14, respectively, were iso-
lated in moderate yields (42 43%) as a dark red (PMI com-
pound) and brownish solids (NMI dendron).
13 carrying two NMI substituents.This reaction proceeded
in a o-xylene/diphenyl ether (1/1) at 1958C over three days.
Workup again required column chromatography, with ace-
tone as an eluent.In this way, the multichromophore 32 was
obtained as a dark purple solid in 63% yield.
Typical MALDI-TOF mass spectra are shown in Figure 4.
The MALDI-TOF spectra of 30 and 32 (matrix: dithranol,
addition of silver triflate; Figure 4) show only one peak at
m/z 9703 and m/z 12165, respectively, in accordance with
the molecular mass of the [M+Ag]+ cluster.The perfect
agreement between the calculated and experimentally deter-
mined m/z ratios for different generations of dendrimers
confirms their monodispersity.
Synthesis of multichromophores: In the last step, TDI core
10 was treated with five equivalents of PMI-cyclopentadie-
none building block 11 in o-xylene at 1708C (Scheme 8).
After 12 h the crude product was purified by column chro-
matography with dichloromethane to give first-generation
multichromophore 29 bearing four PMI substituents at the
periphery.Second-generation multichromophore 30 was ob-
tained by reaction of TDI core 10 with 10 equivalents of
1
Figure 5 shows the H NMR spectrum of 29.Well-separat-
ed and assignable signals are obtained for the aliphatic CH
and (CH3)2 groups of PMI and the TDI core molecule, the
aromatic protons of the bay region of the PMI and TDI
chromophores, and the H-4 protons of the pentaphenyl
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Dendritic Multichromophores
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groups of the dendrimer branches.The signals of the other
aromatic protons of the chromophores and the polypheny-
lene dendrons can not be distinguished due to strong over-
lap.The number of aromatic signals is higher for high-gener-
ation dendrimers, and unstructured signals are obtained in
the aromatic region between d=6.6 and 7.4 ppm.
This is also true of the 1H NMR spectrum of 32
(Figure 6).Here, the aforementioned characteristic signals
of protons in the bay region of
shows the absorption spectra of dyads 29 and 30, TDI chro-
mophore 10, and a series of polyphenylene dendrimers car-
rying a one, four (4, TdPMI4, Scheme 1) and eight PMI
chromophores (5, TdPMI8, Scheme 1) at the periphery,
whose synthesis has already been described by us.[34]
TdPMI4 absorbs at 502 (e=119200) and 526 nm (e=
119200mÀ1 cmÀ1), whereas TDI chromophore 10 absorbs at
667 nm (e=87125mÀ1 cmÀ1, Table 1).The dyad 29 displays
the PMI and TDI chromo-
Table 1. lmax [nm] and e [mÀ1 cmÀ1] of dendrimers 29, 30, 34,32 , and the TDI core 10 in toluene.
phores are still clearly assigna-
ble.Furthermore, additional
signal groups at d=7.87 and
7.79 ppm are detected, which
could correspond to the protons
of the NMI chromophores or to
the protons of the pentaphenyl
groups of the dendrimer
branches.Although the dendrit-
ic triad 32 contains over 500
protons, characteristic signals of
different chromophore substitu-
ents are still evident.
Compound
Absorption
lmax [nm] (e [mÀ1 cmÀ1])
PMI
Emission
lmax [nm]
NMI
TDI
TdG1PMI1
501 (42200)
527 (41400)
502 (119200)
526 (119200)
501 (218300)
525 (216500)
553 (PMI)[b,d]
556 (PMI)[b,d]
557 (PMI)[b,d]
698 (TDI)[c]
4
TdG1PMI4
5
TdG2PMI8
10
-
667
(87125)
675
(85671)
674
(89990)
676
(98462)
29
30
32
501 (118200)
526 (111350)
500 (227270)
524 (222680)
501 (134576)
526 (136565)
559w (PMI)[b]
701s (TDI)
557w (PMI)[b]
702s (TDI)
370 (178854)
432w (NMI)[a]
Isolation of chromophore sites
at the periphery: Figure 7
[a] lexc at 370 nm.[b] lexc =488 nm.[c] lexc =675 nm.[d] Fluorescence quantum yield of 09. 8 in toluene.
Scheme 7.Functionalization of a polyphenylene dendron with PMI and NMI substituents.i) 3 equiv 28, K2CO3, toluene/ethanol, 12 h, 808C, 43%; ii) 3 e-
quiv 15, K2CO3, toluene/ethanol, 12 h, 808C, 42%.
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K.M¸llen et al.
FULL PAPER
Scheme 8.Synthetic approach to dendritic dyads and triads. Synthesis of the dendritic dyads 29, 30, 34, and the triad 32.i) 5 equiv 11, o-xylene, 12 h,
1708C, 92%; ii) 10 equiv 14, o-xylene, three days, 1708C, 83%; iii) a) 5 equiv 12, o-xylene, 12 h, 1708C, 90%; b) 1 equiv nBu4N¥3H2O, THF, 4 min, 88%;
iv) 16 equiv 13, o-xylene/diphenyl ether (1/1), three days, 1958C, 63%.
absorption maxima at 501 (e=118200), 526 (e=11350), and
675 nm (e=85671mÀ1 cmÀ1), corresponding to the absorp-
tion of the PMI and the TDI units.Consequently, the ab-
sorption spectra of 29 and 30 can be approximated as a su-
perposition of the spectra of the constituent moieties.
A direct correlation exists between the number of chro-
mophores and the extinction coefficients at the absorption
maximum (inset to Figure 7).This behavior can be attribut-
ed to the absence of intramolecular chromophore interac-
tions in the ground state and indicates that the chromo-
phores are spatially well isolated at the surface of the den-
drimer.
This observation was also supported by investigating the
three-dimensional structures of 29, 30, and 32.Figure 8
shows the minimized structure[51] of 30 with views of the
imide structure (middle) and bay region (right) of the cen-
tral TDI chromophore.It is evident that the terminal PMI
chromophores are located exclusively at the periphery, spa-
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Dendritic Multichromophores
1398 1414
Vectorial energy transfer: The
synthesis of multichromophores
containing different types of
chromophores enables the in-
vestigation of energy transfer
processes between these chro-
mophores.After exciting the
PMI chromophores of dyad 29
at 488 nm a strong emission at
701 nm occurs (Figure 9), which
is due to efficient energy trans-
fer from the PMI chromo-
phores towards the TDI center.
The emission maxima of the
dyads 29 and 30 are given in
Table 1.This energy transfer
proceeds by the Fˆrster mecha-
nism[48,49] and has already been
investigated in solution[35] and
at the single-molecule level.[50]
Triad 32 bears a TDI chro-
mophore in the center, four
PMI chromophores in the scaf-
fold, and eight NMI chromo-
phores at the periphery.The ab-
sorption spectrum of 32 was
discussed before[35] and it was
pointed out that this multichro-
mophore absorbs over the
whole visible spectrum with
well-separated absorption enve-
lopes.This fact is of special im-
portance with regard to selec-
tive excitation of different chro-
mophore units of the multichro-
mophore.It was shown that ex-
citation
of
the
NMI
chromophores at the periphery
of the dendrimer results in
weak emissions of the NMI and
PMI groups but in strong emis-
sion from the TDI core[35]
(Figure 9).
This behavior has been at-
Figure 4.a) MALDI-TOF mass spectrum of second-generation polyphenylene dyad 30 in the presence of
silver triflate (m/z 9703 [M+Ag]+ ; calcd for 30: 9594).b) MALDI-TOF mass spectrum of triad 32 in the pres- tributed to efficient vectorial
ence of silver triflate (m/z 12165 [M+Ag]+ ; calcd for 32: 12053).
energy transfer from the NMI
donor chromophores at the pe-
riphery via the PMI chromo-
tially well-isolated from each other.Furthermore, it was re-
ported previously that the dynamics of peripheral groups in
high-generation polyphenylene dendrimers are strongly re-
duced due to the formation of a dense shell of phenyl rings
at the outer sphere of the dendrimer.[52] Therefore, the prob-
ability that two chromophores come close enough to form
excimerlike species is low.Consequently, even for polyphe-
nylene dendrimers carrying a high number of terminal chro-
mophores, nearly quantitative fluorescence quantum yields
have been determined (Table 1), which makes these mole-
cules highly fluorescent ™superchromophores∫.
phores in the scaffold towards the TDI center of 32.For vec-
torial transduction of excitation energy, formation of an
energy gradient is required, which has been achieved by spa-
tial localization of the chromophore units by using a poly-
phenylene dendrimer scaffold as a stiff matrix.
The great importance of the PMI chromophores in the
dendritic scaffold for energy transfer becomes obvious when
the emission spectrum of an NMI chromophore is compared
with the absorption spectrum of a TDI chromophore, since
both spectra reveal only a small spectral overlap.However,
an efficient energy transfer according to the Fˆrster mecha-
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K.M¸llen et al.
FULL PAPER
nism[49,50] requires a sufficient
spectral overlap of the constitu-
ent chromophores.Therefore,
the PMI chromophores in the
dendritic scaffold play an essen-
tial role in transferring excita-
tion energy from the NMI
donors towards the TDI accept-
or.In this way, it is a key fea-
ture that the well-separated pe-
ripheral chromophores allow
the transfer of excitation
energy to the center without
sustaining losses due to the for-
mation of excimers.
Conclusion and Outlook
We have presented a new syn-
thetic approach to dendritic
multichromophores containing
up to three different rylene
chromophores at distinct posi-
tions within the dendrimer.A
key step was the development
of new building blocks which
open up the unique possibility
to incorporate functionalities in
the center, scaffold, and periph-
ery of the dendrimer.In this
way, the herein-reported build-
ing-block chemistry allows the
synthesis of a large variety of
different multichromophores in
which the number of chromo-
phores and the interchromo-
phore distances can easily be
changed.To realize this con-
cept, two different dyads 29 and
30 containing a TDI core and a
PMI periphery were prepared.
With regard to synthesis the
dendritic triad 32 consisting of
NMI chromophores at the pe-
riphery, PMI chromophores
within the dendritic scaffold,
and a TDI chromophore at the
center is the first example of a
dendrimer bearing three differ-
ent types of chromophores.As
a special feature, the chromo-
phores with different absorp-
tion and emission wavelengths
are localized precisely and form
an energy gradient from the pe-
riphery towards the center.The
occurrence of energy transfer
was shown for the dyads and
Figure 5.500 MHz 1H NMR spectrum of 29 in [D8]THF at 298 K.
Figure 6.500 MHz 1H NMR spectrum of triad 32 in [D8]THF at 298 K.
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Dendritic Multichromophores
1398 1414
for the triad.In case of the den-
dritic triad, vectorial energy
transfer proceeds stepwise from
the chromophores at the pe-
riphery over the functionalized
scaffold towards the center.
Time-resolved
spectroscopy
fluorescence
measurements,
which are currently underway,
will provide deeper insight into
the energy-transfer processes
taking place in such a complex
but still highly ordered macro-
molecule as the herein-present-
ed triad.
The chief merits of these new
dendrimers are high spatial res-
olution of different types of
chromophores by a stiff back-
bone which, due to its structure,
isolates the chromophores and
does not participate in energy
transfer.Due to the high photo-
chemical stability of the chro-
mophore units, the dendritic
dyads and triad reported herein
can be used for single-molecule
spectroscopy, which could give
new insight into interactions of
chromophores in close proximi-
ty and defined environment.
Thus, these novel dendrimers
Figure 7.Absorption spectra of a series of polyphenylene dendrimers based on a tetrahedral core bearing one
(TdG1PMI1), four (4, TdG1PMI4), and eight (5, TdG2PMI8) PMI chromophores at the periphery, as well as of
the TDI core 10 and the dyads 29 (dashed line) and 30 (dotted line) in toluene.Inset: Number of PMI chro-
mophores of the dendrimer versus the extinction coefficient at the first absorption maximum of the PMI unit
and correlation function with correlation factor.
Figure 8.Left: 2D structure of 30.Middle: 3D structure of 30 with view over a) the imide structure and b) the bay-region of the central TDI-chromo-
phore.[51]
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K.M¸llen et al.
FULL PAPER
(d, 3J(H,H)=6.71 Hz, 24H); 13C NMR
(67 MHz, CD2Cl2): d=161.4, 144.93,
137.7, 137.4, 133.5, 129.6, 129.4, 128.4,
128.3, 127.1, 126.12, 123.3, 120.9, 119.7,
28.8, 23.5 ppm; IR (KBr pellet): n˜ =
2963, 2927, 2867, 1711 (C=O), 1672
(C=O), 1583, 1465, 1389, 1347, 1308,
1236, 1172, 1198, 846, 810 cmÀ1; UV/
Vis (CHCl3): lmax (e)=656 (93325),
605 (46773), 559 nm (15848mÀ1 cmÀ1);
Elemental analysis (%) calcd for
C58H42N2O4Br4: C, 60.55; H, 3.68; N,
2.43; Found: C, 60.52; H, 3.69; N, 2.44.
8: Compound 7 (224 mg, 0.195 mmol),
4-iodophenol (644 mg, 2.925 mmol),
and K2CO3 (202 mg, 1.46 mmol) were
heated
in
N-methylpyrrolidone
(34 mL) at 908C under argon for 17 h.
After cooling to room temperature the
reaction mixture was poured into HCl
(2n, 100 mL).The crude solid was sep-
arated under vacuum, dissolved in di-
chloromethane, and
dried over
MgSO4.Column chromatography on
silica gel with dichloromethane as
eluent gave 8 (182 mg, yield: 55%) as
a blue solid, m.p. >3008C; MS (FD,
8 kV): m/z (%): 1707 [M]+, 853 [M]2+
,
(calcd for C82H58I4N2O8: 1707.00);
1H NMR (500 MHz, C2D2Cl4, 363 K):
d=9.29 (s, 4H), 8.18 (s, 4H), 7.66 (d,
3J(H,H)=8.85 Hz, 8H), 7.37 (t,
3J(H,H)=7.65 Hz, 2H), 7.21 (d,
3J(H,H)=7.65 Hz, 4H), 6.91 (d,
3J(H,H)=8.85 Hz, 8H), 2.58 (sept.,
3J(H,H)=6.7 Hz, 4H), 1.15 (s, 84H),
1.05 (d, 3J(H,H)=6.75 Hz, 24H);
13C NMR (75 MHz, C2D2Cl4, 363 K):
Figure 9.Emission spectra of dyad 29 (lexc =488 nm, dashed line) and triad 32 (lexc =370 nm, straight line) in
toluene, and chemical structure of the chromophore units at their emission area (D marks the positions at
which the polyphenylene dendrons are attached to the chromophore).
are attractive candidates for a better understanding of pho-
d=161.4, 154.7, 153.1, 144.9, 138.8, 138.6, 137.7, 137.4, 133.5, 130.4, 129.9,
129.6, 128.5, 128.3, 127.9, 127.1, 126.1, 125.4, 123.3, 122.5, 121.7, 120.4,
119.7, 28.3, 23.1 ppm; IR (KBr pellet): n˜ =3052, 3023, 2962, 2869, 1702,
1664, 1590, 1498, 1357, 1243, 1176, 1072, 840, 811, 754, 700 cmÀ1; Elemen-
tal analysis (%) calcd for C82H58I4N2O8: C, 57.70; H, 3.42; N, 1.64;
Found: C, 57.61; H, 3.36; N, 1.62.
tophysical processes such as those observed in natural multi-
chromophore arrays.Since the dendritic triad absorbs light
energy over the whole visible spectrum, this compound is
currently being investigated with a view to its suitability for
the development of novel emissive layers for the design of
photonic devices.
9: Compound
8
(181 mg, 0.106 mmol), triisopropylsilylacetylene
(0.12 mL, 0.530 mmol), copper(i) iodide (8.1 mg, 0.0424 mmol), triphenyl-
phosphane (11 mg, 0.0424 mmol), and [PdCl2(PPh3)2] (15 mg,
0.0212 mmol) were dissolved in dry THF (7 mL) and dry triethylamine
(2.3 mL) at RT under argon with exclusion of light. After 24 h, the
Experimental Section
reaction mixture was poured into
a solution consisting of distilled
water (50 mL) and hydrochloric acid (25 mL, 2n) and stirred for a few
minutes.Then, the mixture was extracted several times with dichloro-
methane and then with a saturated solution of ammonium chloride.
The organic phases were washed with distilled water, dried over MgSO4,
and purified by column chromatography with dichloromethane/petrole-
um ether as eluent (1/1, Rf =0.94). Mixed fractions were separated by
further column chromatography with petroleum ether/dichloromethane
(1.5/1, Rf =0.32) to afford 9 (115 mg, 60%) as a blue solid, m.p. >3008C;
MS (FD, 8 kV) m/z (%): 1925 [M]+, 962 [M]2+ (calcd for
C126H142N2O8Si4: 1925); 1H NMR (300 MHz, CD2Cl2): d=9.31 (s, 4H),
8.22 (s, 4H), 7.44 (d, 3J(H,H)=8.55 Hz, 8H), 7.40 (t, 3J(H,H)=7.95 Hz,
2H), 7.23 (d, 3J(H,H)=7.95 Hz, 4H), 7.03 (d, 3J(H,H)=9.2 Hz, 8H),
2.61 (sept., 3J(H,H)=6.7 Hz, 4H), 1.15 (s, 84H), 1.04 (d, 3J(H,H)=
6.7 Hz, 24H); 13C NMR (75 MHz, [D2]CD2Cl2): d=163.00 (q, C=O),
156.34 (q), 153.61 (q), 146.11(q), 134.25 (t), 131.25 (q), 131.02 (q),
129.59 (t), 129.43 (q), 129.06 (t), 128.87 (q), 126.97 (q), 124.95 (t), 124.15
(t), 123.91 (q), 122.62 (q), 118.7 (t), 118.23 (q), 107.79 (q, C ethynyl),
90.96 (CH ethynyl), 29.17 (t, CHCH3), 23.78 (t, CHCH3), 17.57 (CH
TiPS), 12.44 (CH3-TiPS); Elemental analysis (%) calcd for
C126H142N2O8Si4: C, 78.62; H, 7.44; N, 1.46; Found: C, 78.73; H, 7.39; N,
1.44.
General: The solvents used were of commercial grade; THF was dried
over potassium; toluene was distilled from sodium. 1H NMR and
13C NMR spectra were recorded on
a Bruker DRX 500 (500 and
125 MHz, respectively) or Bruker AMX 300 (300 and 75 MHz, respec-
tively).Mass spectra were recorded on a Bruker MALDI-TOF spectrom-
eter.UV/Vis data were obtained on a Perkin-Elmer Lambda 9, and fluo-
rescence spectra were measured on a SPEX Fluorolog 2 Type 212 spec-
trometer.[Pd(PPh )4] and [PdCl2(dppf)]¥CH2Cl2 (dppf=1,1’-bis(diphenyl-
3
phosphanyl)ferrocene) catalysts were purchased from ABCR.
N,N’-Bis(2,6-diisopropylphenyl)-1,6,9,13-tetrabromoterrylen-3,4:11,12-tet-
racarbooxdiimide (7): N,N’-Bis(2,6-diisopropylphenyl)terrylen-3,4:11,12-
tertacarboxdiimide (6, 834 mg, 1 mmol) was dissolved in chloroform
(50 mL).Then bromine (5 mmol) was added and the reaction mixture
was heated to reflux for 12 h with exclusion of light.Thereafter, the mix-
ture was flushed with nitrogen to remove remaining bromine, and the
solvent was evaporated under vacuum.Column chromatography on silica
gel with dichloromethane as eluent afforded 7 (900 mg, 75%) as a blue
solid, m.p. >3008C; MS (FD, 8 kV): m/z (%): 1145.3 [M]+ 1H NMR
;
(500 MHz, CDCl3): d=9.52 (s, 2H), 8.92 (s, 2H), 7.44 (t, 3J(H,H)=
7.78 Hz, 2H), 7.29 (d, 3J(H,H)=7.94 Hz, 4H), 2.70 (m, 4H), 1.16 ppm
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Dendritic Multichromophores
1398 1414
10: Compound 9 (211 mg, 0.191 mmol) was dissolved in freshly distilled
THF (12 mL) and flushed with argon for 10 min.Then, a solution of
Bu4NF¥3H2O (60 mg, 0.191 mmol) in dry THF (2 mL) was added. The re-
action mixture immediately turned dark, and the progress of the reaction
was monitored by TLC with petroleum ether/dichloromethane (1/1, Rf =
0.71). After 4 min the reaction was finished, and distilled water (20 mL)
was added.Then the crude mixture was extracted with dichloromethane
and washed with water.The organic phases were dried over MgSO 4, and
the solvent was evaporated under reduced pressure.Column chromatog-
raphy with dichloromethane/petroleum ether (1/1) gave 9 (226 mg, 91%)
as a dark blue solid, m.p. >3008C; MS (FD, 8 kV): m/z=1299 [M]+
(calcd for C90H62N2O8 =1299 g/mol); 1H NMR (500 MHz, CD2Cl2): d=
9.30 (s, 4H), 8.23 (s, 4H), 7.44 (d, 3J(H,H)=8.55 Hz, 8H), 7.40 (t,
3J(H,H)=7.95 Hz, 2H), 7.24 (d, 3J(H,H)=7.95 Hz, 4H), 7.03 (d,
3J(H,H)=9.2 Hz, 8H), 3.04 (s, 4H), 2.62 (sept., 3J(H,H)=6.7 Hz, 4H),
1.04 (d, 3J(H,H)=6.7 Hz, 24H); 13C NMR (75 MHz, CD2Cl2): d=163.00
(q, C=O), 156.34 (q), 153.61 (q), 146.11(q), 134.25 (t), 131.25 (q), 131.02
(q), 129.59 (t), 129.43 (q), 129.06 (t), 128.87 (q), 126.97 (q), 124.95 (t),
124.15 (t), 123.91 (q), 122.62 (q), 118.7 (t), 118.23 (q), 82.70 (q, C ethyn-
yl), 77.28 (CH ethynyl), 29.17 (t, CHCH3), 23.78 (t, CHCH3); UV/Vis
(CHCl3): lmax (e)=665 nm (88865mÀ1 cmÀ1); IR (KBr pellet): n˜ =2921
(s), 2850 (s), 1702, 1660, 1589, 1504, 1463, 1328, 1278, 1207 cmÀ1; Elemen-
tal analysis (%) calcd for C90H62N2O8: C, 83.19; H, 4.81; N, 2.16; Found:
C, 83.01; H, 4.78; N, 2.13.
124.46, 123.59, 123.47, 123.71, 121.99, 29.56, 24.04 ppm; elemental analy-
sis (%) calcd for C137H102N2O5: C 88.64, H 5.54, N 1.51; found: C 88.19,
H 5.38, N 1.43.
14: Compound 27 (1.89 g, 1.4 mmol) and 15 (3 g) were dissolved in tolu-
ene (59 mL).Ethanol (11 mL) and a solution K 2CO3 (9.65 g) in water
(28 mL) were added, and the mixture was flushed with argon.
[Pd(PPh3)4] catalyst (167 mg, 0.14 mmol) was added, and the reaction
mixture stirred at 808C for 24 h.The resulting solution was washed three
times with water and dichloromethane.The organic phases were separat-
ed and dried over MgSO4.The crude product was purified by chromatog-
raphy with dichloromethane to afford 14 (1.24 g, 42%) as a red solid;
m.p. >3008C; MS (FD, 8 kV): m/z (%): 2104 (87) [M]+, 1052 (13) [M]2+
(calcd for C157H110N2O5: 2104.64); 1H NMR (250 MHz, [D8]THF): d=
8.56 8.54 (m, 12H), 7.62 6.71 (m, 72H), 2.78 (sept., 4H, CHCH3),
1.12 ppm (d, 3J(H,H)=6.48 Hz, 24H, CHCH3); 13C NMR (75 MHz,
[D8]THF): d=200.18 (q, C=O), 164.60, 154.95, 147.13, 143.07, 142.96,
142.39, 142.32, 141.95, 141.75, 141.43, 141.21, 141.06, 138.68, 138.52,
138.25, 133.9, 132.88, 132.62, 132.38, 131.69, 131.28, 131.26, 131.11, 130.74,
130.58, 130.28, 129.96, 129.75, 129.51, 129.19, 128.93, 128.77, 128.10,
127.92, 127.62, 127.13, 126.91, 126.63, 126.41, 125.18, 124.82, 124.58,
122.54, 122.41, 121.72, 121.50, 30.27, 24.57 ppm; IR (KBr pellet): n˜ =
3063, 2963, 2868, 1698, 1659, 1593, 1570, 1505, 1467, 1449, 1403, 1360,
1329, 1294,1247, 1201, 1170, 1164, 1135, 1034, 946, 906, 875, 854, 844, 813,
753, 713, 703, 689, 658, 645 cmÀ1; UV/Vis (CHCl3): lmax (e)=482 (43000),
505 nm (42000mÀ1 cmÀ1); elemental analysis (%) calcd for C157H110N2O5:
C 89.60, H 5.27, N 1.33; found: C 89.14, H 5.23, N 1.31.
12: Compound 17 (1 g, 1.44 mmol) and 15 (0.450 g, 1.81 mmol) were dis-
solved in toluene (82.5 mL). Ethanol (6.05 mL) and a solution of K2CO3
(9.75 g) in water (32 mL) were added, and the mixture was flushed with
argon.[Pd(PPh 3)4] catalyst (84 mg, 0.073 mmol) was added, and the reac-
tion mixture stirred at 808C for 12 h.The resulting solution was washed
three times with distilled water and dichloromethane.The organic phases
were separated and dried over MgSO4.The crude product was purified
by chromatography with dichloromethane (Rf =0.77). Mixed fractions
were purified by column chromatography with dichloromethane/petrole-
um ether (1.5/1, Rf =0.2) to give 17 (3.35 g, 59%) as a red solid; m.p. >
3008C; MS (FD, 8 kV): m/z (%): 1044 (100) [M]+ (calcd for
C74H65NO3Si: 1044.43); 1H NMR (250 MHz, [D8]THF, 289 K): d=8.59
8.52 (m, 6H), 7.93 (d, 3J(H,H)=8.37 Hz, 1H), 7.63 (m, 2H), 7.45 7.04
(m, 21H), 2.80 (sept., 5H), 1.14 ppm (br, 30H); 13C NMR (75 MHz,
[D8]THF, 289 K): d=200.13 (q, C=O), 164.60 (q, C=O), 154.99 (q),
154.54 (q), 147.15 (q), 143.56 (q), 141.44 (q), 138.63 (q), 138.38 (q),
135.00 (q), 134.99 (q), 133.62 (q), 133.03 (q), 132.74 (t), 132.26 (q), 132.10
(q), 131.67 (q), 131.38 (t), 131.05 (q), 130.88 (t), 130.13, 129.9, 129.82,
129.65, 129.48, 129.12 (t), 129.06 (t), 128.65 (t), 128.24 (q), 128.11 (q),
127.10 (q), 126.93 (q), 125.33 (q), 124.92 (t), 124.77 (q), 124.60 (t), 122.64
(q), 122.58(q), 122.88 (t), 121.72 (t), 108.44 (q), 92.56 (q), 30.92 (t,
CH(CH3)2), 24.49 (t, CH(CH3)2), 19.36 (t, SiCH(CH3)2), 12.56 ppm (t,
SiCH(CH3)2); IR (KBr pellet): n˜ =3056, 2961, 2928, 2867, 1701, 1661,
1592, 1574, 1443, 1358, 1293, 1245, 1197, 1178, 911, 834, 811, 752, 725,
706, 693 cmÀ1; UV/Vis (CHCl3): lmax (e)=250 (56400), 482 (43000),
505 nm (42000mÀ1 cmÀ1); elemental analysis (%) calcd for C74H65NO3Si:
C 85.10, H 6.27, N 1.34; found: C 84.83, H 6.45, N 1.33.
N-(2,6-Diisopropylphenyl)-9-(4,4,5,5-teramethyl-1,3,2-dioxaborolan-2-yl)-
perylene-3,4-dicarboximide (15): A mixture of N-(2,6-diisopropylphenyl)-
9-bromoperylene-3,4-dicarboximide (1.1 g, 0.2 mmol), bis(pinacolato)di-
boron (558 mg, 2.5 mmol), and potassium acetate (588 mg, 5.3 mol) was
dissolved in dioxane (20 mL) under an argon atmosphere.
[PdCl2(dppf)]¥CH2Cl2 catalyst (44 mg, 0.1 mmol) was added, and the re-
sulting mixture stirred for 16 h at 708C.Then the product mixture was
washed with distilled water and dichloromethane.The dichloromethane
layer was separated, dried over MgSO4, and the crude product purified
by column chromatography with dichloromethane to afford 15 (0.9 g,
75%) as a red solid, m.p. >2008C; MS (FD, 8 kV): m/z (%): 607.4 (100)
[M]+ 1H NMR (250 MHz, CD2Cl2, 258C): d=8.86 (d, J=8.25 Hz, 1H),
;
8.62 (dd, 2H), 8.43 (m, 4H), 8.16 (d, J3(H,H)=7.57 Hz, 1H), 7.63 (t,
7.59 Hz, 1H), 7.50 (t, 7.74 Hz, 1H), 7.35 (d, 3J(H,H)=7.58 Hz, 2H), 2.79
(h, 2H), 1.46 (s, 12H), 1.15 ppm (d, 12H); 13C NMR (62.5 MHz, CD2Cl2,
258C): d=165.85, 165.80, 147.94, 139.57, 138.93, 137.83, 133.59, 133.46,
133.39, 133.17, 132.13, 131.07, 130.55, 129.31, 128.73, 128.50, 125.80,
125.46, 124.60, 123.02, 122.56, 122.47, 122.04, 86.09, 30.69, 26.60, 25.56,
25.53 ppm; UV/Vis (CHCl3): lmax (e)=241 (28159), 265 (30569), 485
(36712), 515 nm (36897mÀ1 cmÀ1); IR (KBr pellet): n˜ =2970, 2862, 1708,
1667, 1594, 1512, 1470, 1429 1367, 1336, 1243, 1144, 1113, 963, 865, 818,
762 cmÀ1; elemental analysis (%) calcd for C40H38NO4B: C 79.08, H 6.30,
N 2.31; found: C 78.53, H 6.91, N 2.25.
3-(4-Bromophenyl)-2,5-diphenyl-[4-(triisopropylsilylethynyl)phenyl]cy-
clopenta-2,4-dien-1-one (17): 4,4’-Bis(triisopropylsilylethynyl)benzil (23,
4.92 g, 23.4 mmol) and 1,3-diphenylacetone (24, 10 g, 21.3 mmol) were
heated in tert-butyl alcohol (30 mL) at 808C.Tetrabutylammonium hy-
droxide (10.11 mL) in methanol (0.8m) was added, and the reaction mix-
ture was stirred for 15 min at 908C.The reaction mixture was washed
three times with water and dichloromethane, and the organic phases
were separated and dried over MgSO4.The crude product was purified
by column chromatography with dichloromethane/petroleum ether (1/1)
to give 17 as a brown powder (2.1 g, 78%); m.p. 100 1158C (decomp);
MS (FD, 8 kV): m/z (%): 643 (100) [M]+ (calcd for C40H39BrOSi:
643.75); 1H NMR (300 MHz, [D8]THF, 298 K): d=7.40 (d, 3J(H,H)=
8.37 Hz, 2H), 7.31 (d, 3J(H,H)=8.76 Hz, 2H), 7.23 7.19 (m, 10H), 6.95
(d, 3J(H,H)=8.4 Hz, 2H), 6.89 (d, 3J(H,H)=8.4 Hz, 2H), 1.15 ppm (m,
21H, Halkyl); 13C NMR (75 MHz, [D8]THF, 298 K): d=199.59, 153.94,
153.79, 134.33, 133.26, 132.51, 132.29, 132.13, 131.66, 131.64, 131.03,
130.99, 130.40, 128.79, 128.34, 126.78, 124.47, 123.61, 108.01, 92.28, 19.05,
12.24 ppm; elemental analysis (%) calcd for C40H39BrOSi: C 74.63, H
6.11; found: C 74.65, H 6.21.
13: Compounds 27 (1 g, 0.767 mmol) and 28 (1.26 g, 2.61 mmol) were dis-
solved in toluene (31 mL).Ethanol (6 mL) and a solution of K 2CO3
(5.1 g) in H2O (15 mL) were added, and the mixture was flushed with
argon.[Pd(PPh )4] catalyst (100 mg, 0.0865 mmol) was added, and the re-
3
action mixture stirred at 808C for 12 h.The resulting solution was
washed three times with distilled water and dichloromethane.Then, the
organic phases were separated and dried over MgSO4.The crude product
was purified by chromatography with dichloromethane (Rf =0.50). Mixed
fractions were purified thereafter by column chromatography with di-
chloromethane/petroleum ether (1.5/1, Rf =0.12) to give 13 (612 mg,
43%) as a brownish yellow solid; m.p. >3008C; MS (FD, 8 kV): m/z:
1856 [M]+ (calcd for C137H102N2O5 =1856.35); 1H NMR (300 MHz,
CD2Cl2, 298 K): d=8.63 8.57 (m, 4H), 7.93 7.91 (m, 1H), 7.86 7.83 (m,
1H), 7.74 7.59 (m, 6H), 7.50 7.46 (m, 2H), 7.35 6.89 (m, 60H), 6.72
6.69 (m, 4H), 2.73 (sept., J=6.7 Hz, 4H), 1.11 ppm (d, J(H,H)=6.7 Hz,
24H); 13C NMR (75 MHz, CD2Cl2, 298 K): d=200.39 (q, C=O), 164.56,
154.47, 147.47, 143.71, 142.51, 142.45, 142.27, 142.01, 141.66, 141.43,
141.22, 141.09, 136.45, 136.21, 133.33, 132.91, 132.28, 132.17, 131.63,
131.30, 130.86, 130.55, 130.35, 129.96, 129.75, 129.51, 129.19, 128.93,
128.77, 128.10, 127.92, 127.62, 127.13, 126.94, 126.85, 126.35, 125.93,
4-(Bromophenylethynyl)trimethylsilane (19): 4-Bromoiodobenzene (18,
50 g, 0.1767 mol), trimethylsilylacetylene (34.88 mL, 0.246 mol), copper(i)
iodide (4.5 g, 0.0237 mol), triphenylphosphane (3.6 g, 0.0137 mol), and
1411
Chem. Eur. J. 2004, 10, 1398 1414
www.chemeurj.org
¹ 2004 Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim

K.M¸llen et al.
FULL PAPER
[PdCl2(PPh3)2] catalyst (5 g, 0.007 mol) were dissolved in dry toluene
(270 mL) and dry triethylamine (450 mL) under argon at room tempera-
ture with exclusion of light.After 24 h, the reaction mixture was poured
into a solution of distilled water (50 mL) and hydrochloric acid (25 mL,
2n) and stirred for a few minutes.The mixture was extracted several
times with dichloromethane and then with a saturated solution of ammo-
nium chloride.The organic phases were washed with distilled water,
dried over MgSO4, and purified by column chromatography with petrole-
um ether to afford 19 (40 g, 89%) as a colorless oil; MS (FD, 8 kV): m/z
(%): 253 (100) [M]+ (calcd for C11H13BrSi: 253.22); 1H NMR (300 MHz,
CDCl3, 298 K): d=7.44 (d, J(H,H), 8.45 Hz, 2H), 7.33 (d, J(H,H)=8.49,
2H), 0.05 ppm (s, 9H); 13C NMR (75 MHz, CDCl3, 298 K): d=133.55,
131.65, 123.17, 104.04, 95.59, 78.37 (CBr), 0.08 ppm; IR (film): n˜ =3267,
140.87 (q), 140.74 (q), 140.69 (q), 140.61 (q), 140.48 (q), 140.37 (q),
140.23 (q), 134.46 (t), 132.58 (t), 132.44 (q), 132.38 (q), 131.65 (t), 131.27
(t), 131.00 (t), 130.97 (t), 130.27 (t), 128.89 (t), 128.74 (t), 128.46 (t),
128.29 (t), 128.26 (t), 127.96 (t), 127.71 (q), 127.54 (q), 127.41 (q), 127.19
(q), 127.10 (q), 126.83 (q), 120.99 (q), 120.72 ppm (q); elemental analysis
(%) calcd for C47H48Br2O2: C 78.73, H 4.29; found: C 78.13, H 4.26.
27: Compound 26 (3.5 g, 3.1 mmol) and diphenylacetone (24, 0.717 g,
3.41 mmol) were dissolved in toluene (100 mL) under inert conditions.
The reaction mixture was heated to 908C, then tetrabutylammonium hy-
droxide (2.1 mL, 0.8m) was added slowly by syringe, and the reaction
mixture stirred for 40 min at 908C.FD mass spectrometry was used to
monitor the reaction.Then, water was carefully added to the hot reaction
mixture.After cooling to room temperature, the reaction mixture was
washed several times with water and dichloromethane.The organic
phases were collected, dried over MgSO4, and the solvent evaporated.
Column chromatography with CH2Cl2/petroleum ether (1/3, Rf =0.29)
gave 27 (2.53 g, 63%) as a brown solid; m.p. >3008C; MS (FD, 8 kV):
2976, 1902, 1584, 1484, 1069, 821 cmÀ1
.
1-(Triisopropylsilanylethynyl)-4-trimethylsilanylethynylbenzene
(20):
Compound 19 (45 g, 0.1772 mol), triisopropylsilylacetylene (32 g,
0.1772 mol), copper(i) iodide (4.5 g, 0.0237 mol), triphenylphosphane
(3.5 g, 0.0134 mol), and [PdCl2(PPh3)2] (5 g, 0.007 mol) were dissolved in
toluene (270 mL) and triethylamine (450 mL) according to the procedure
for the synthesis of 19.After column chromatography with petroleum
ether 20 (60.1 g, 95%) was isolated as a colorless oil. MS (FD, 8 kV): m/z
(%): 354 (100) [M]+ (calcd for C22H340Si2: 354.69); 1H NMR (300 MHz,
CDCl3, 298 K): d=7.39 (s, 4H), 1.12 (m, 21H), 0.25 ppm (s, 9H);
13C NMR (75 MHz, CDCl3, 298 K): d=131.86, 131.76, 123.59, 122.99,
106.61, 104.67, 96.16, 92.81, 18.71, 11.33, 0.04 ppm; IR (film): n˜ =
2159 cmÀ1 (m, CꢀC).
(4-Ethynylphenylethynyl)triisopropylsilylsilane (21): Compound 20 (60 g,
0.169 mol) was dissolved in THF (500 mL). Then ethanol (500 mL) and
sodium hydroxide (6.77 g) dissolved in water (170 mL, 1m) were added,
and the reaction mixture was stirred for 2 h at 808C under argon.Then
the mixture was extracted several times with dichloromethane, and the
organic phases were washed with distilled water and dried over MgSO4.
After filtration and evaporation of the solvent, 21 (40 g, 84%) was ob-
tained as a colorless solid; m.p. 43 458C; MS (FD, 8 kV): m/z: 282 [M]+
(calcd for C19H26Si: 282.51); 1H NMR (300 MHz, CDCl3, 298 K): d=7.40
(s, 4H), 3.13 (s, 1H), 1.19 1.07 ppm (m, 21H); 13C NMR (75 MHz,
CDCl3, 298 K): d=131.76, 131.67, 123.46, 121.99, 106.28, 93.39, 83.17,
78.93, 18.7, 11.34 ppm; IR (KBr pellet): n˜3295, 2960, 2899, 2159, 1495,
1403, 1251, 1222, 1103, 1018, 839, 760, 732, 700, 628 cmÀ1; elemental anal-
ysis (%) calcd for C19H26Si: C 80.78, H 9.28; found: C 80.71, H 9.24.
m/z (%): 1303 (68) [M]+
;
651 (32) [M]2+ (calcd for C89H58Br2O:
1303.26); 1H NMR (300 MHz, CD2Cl2, 298 K): d=7.53 (s, 2H), 7.26 7.17
3
(m, 20H, Harom), 7.08 (d, 2H, J(H,H)=8.4 Hz), 7.04 6.7 (m, 32H, Harom),
6.67 ppm (d, 3J(H,H)=8.4 Hz, 2H); 13C NMR (75 MHz, CD2Cl2, 298 K):
d=200.34, 154.44, 142.43, 142.38, 142.04, 141.95, 141.80, 141.38, 141.18,
141.01, 140.81, 140.44, 140.12, 139.95, 139.80, 139.60, 138.70, 133.58,
133.52, 131.87, 131.78, 131.73, 131.38, 131.31, 131.23, 130.51, 130.39,
130.28, 130.11, 129.77, 129.27, 128.35, 128.15, 127.98, 127.71, 127.43,
127.22, 127.16, 126.92, 126.78, 126.43, 126.26, 126.01, 125.71, 120.14,
119.86 ppm; elemental analysis (%) calcd for C89H58Br2O: C 82.02, H
4.49; found: C 82.29, H 4.73.
N-(2,6-Diisopropylphenyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)-1,8-naphthalenedicarboximide (28): N-(2,6-Diisopropylphenyl)-4-
bromo-1,8-naphthalenedicarboximide (1 g, 2.3 mmol), bis(pinacolato)di-
boron (700 mg, 2.7 mmol), [PdCl2(dppf)]¥CH2Cl2 (131 mg, 0.16 mmol),
and potassium acetate (270 mg, 2.75 mmol) were dissolved in toluene
(150 mL) under argon.The reaction mixture was stirred for 48 h at 60 8C.
Then the solvent was evaporated under vacuum while keeping the tem-
perature of the reaction mixture below 608C.Then the crude product
was purified by column chromatography with dichloromethane/pentane
(4/1) to afford 28 (533 mg, 48%) as a light yellow solid; MS (FD, 8 kV):
m/z (%): 483.1 (100) [M]+ 1H NMR (500 MHz, CDCl3): d=9.18 (d,
;
3J(H,H)=8.16, 1H), 8.63 (m, 2H), 8.35 (d, 3J(H,H)=7.22, 1H), 7.84 (t,
3
J=7.86, 1H), 7.48 (t, J=7.86, 1H), 7.31 (d, J(H,H)=7.53, 2H), 2.72 (m,
[4-(4-Bromophenylethynyl)phenylethynyl]triisopropylsilane (22): Com-
pound 21 (40 g, 0.1418 mol), 4-bromiodobenzene (18, 40 g, 0.1418 mol),
copper(i) iodide (2.68 g, 0.0141 mol), triphenylphosphane (3.695 g, 0.0141
mol), and [PdCl2(PPh3)2] (5.14 g, 0.007 mol) were dissolved in toluene
(600 mL) and triethylamine (800 mL) according to the procedure for the
synthesis of 19.After column chromatography with petroleum ether, 22
(50.5 g, 81%) was isolated as a colorless solid; MS (FD, 8 kV): m/z (%):
437 (100) [M]+ (calcd for C25H29BrSi: 437.5); 1H NMR (300 MHz,
CDCl3, 298 K): d=7.68 (d, 3J(H,H)=8.3 Hz, 2H), 7.45 (s, 4H), 7.23 (d,
3J(H,H)=8.3 Hz, 2H), 1.04 ppm (m, 21H); 13C NMR (75 MHz, CDCl3,
298 K): d=137.16, 133.98, 131.98, 131.49, 123.21, 122.95, 122.58, 104.60,
98.31, 96.58 (CBr), 90.49, 90.40, 19.8, 12.4 ppm; IR (KBr pellet): n˜ =2284
(w, CꢀC), 2162 cmÀ1 (m, CꢀCSi); elemental analysis (%) calcd for
C25H29BrSi: C 68.64, H 6.68; found: C 68.57, H 6.66.
2H), 1.44 (s, 12H), 1.14 ppm (d, 3J(H,H)=6.59, 12H); 13C NMR
(125 MHz, C2D2Cl4, 908C): d=163.96, 145.67, 135.35, 134.99, 133.97,
131.13, 131.00, 130.83, 129.68, 128.93, 128.15, 126.77, 126.67, 124.33,
123.58, 122.26, 84.29, 28.66, 24.39 ppm; IR (KBr): n˜ =2964, 2930, 2869,
1711, 1671, 1590, 1469, 1434, 1360, 1239, 1193, 839, 786, 705 cmÀ1; UV/Vis
(CHCl3): lmax (e)=257 (17446), 356 (10347), 370 nm (8665mÀ1 cmÀ1); ele-
mental analysis (%) calcd for C30H34BNO4: C 74.54, H 7.09, N 2.90;
found: C 74.73, H 7.15, N 2.82.
29: Compounds 10 (40 mg, 0.031 mmol) and 11 (150 mg, 0.174 mmol)
were heated in o-xylene (2 mL) under inert conditions for 12 h at 1708C.
Then, the solvent was evaporated under vacuum, and the crude product
purified by column chromatography on silica gel by first eluting with di-
chloromethane until red fractions were no longer collected.Then acetone
was used as an eluent (Rf(29)<0.1). Finally, the product was eluted with
THF to give 29 (132 mg, 92%) as a violet solid; m.p. >3008C; MALDI-
TOF MS: m/z: 4641 [M]+ (calcd for C338H242N6O16: 4643); 1H NMR
(500 MHz, [D8]THF, 298 K): d=9.51 (s, 4H), 8.55 (m, 24H), 8.24 (s, 4H,
H), 7.71 (s, 4H), 7.60 6.91 (m, 122H), 2.80 (m, 12H), 1.14 ppm (m,
72H); 13C NMR (125 MHz, [D8]THF, 298 K): d=164.61 (q), 163.81 (q),
156.09 (q), 155.61 (q), 147.13 (q), 144.19 (q), 142.83 (q), 142.71 (q),
142.61 (q), 142.52 (q), 142.36 (q), 142.29 (q), 142.22 (q), 141.58 (q),
141.44 (q), 141.13 (q), 140.81 (q), 140.65 (q), 140.40 (q), 140.17 (q),
139.61 (q), 138.74 (q), 138.68 (q), 138.49 (q), 133.93 (q), 133.29 (t), 132.97
(t), 132.80 (t), 132.62 (t), 131.93 (t), 131.23 (t), 131.07 (t), 130.54 (q),
130.25 (t), 129.95 (t), 129.69 (t), 129.66 (t), 129.47 (q), 128.93 (t), 128.47
(t), 128.21 (t), 128.06 (q), 127.69 (t), 127.20 (t), 126.65 (q), 125.21 (t),
124.80 (t), 124.59 (t), 123.85 (q), 122.48 (q), 122.35 (q), 121.65 (t), 121.45
(t), 121.26 (q), 120.99 (q), 120.03 (t), 30.24 (t, CH(CH3)2), 24.73 ppm (t,
CH(CH3)2); UV/Vis (CHCl3): lmax (e)=509 (135016), 526 (133404),
675 nm (85635mÀ1 cmÀ1); IR (KBr pellet): n˜ =700, 754, 811, 840, 931,
26: Diethynylbenzil (25, 1.7 g, 6.58 mmol) and 3-(4-bromo-phenyl)-2,4,5-
triphenylcyclopentadienone (16, 7.3 g, 15 mmol) were dissolved in o-
xylene (100 mL) and heated for 12 h at 1708C under inert conditions.
After cooling to RT the crude product was dissolved in the minimum
amount of dichloromethane and added slowly to methanol (700 mL).The
resulting precipitate was collected by filtration under vacuum, redissolved
in dichloromethane and reprecipitated by addition to methanol.This pro-
cedure was repeated until a bright yellow solid was obtained.To increase
the overall yield, the filtrates were collected, the solvent was evaporated,
and the crude product was purified by column chromatography with di-
chloromethane/petroleum ether (1/2, Rf =0.16). 26 (7.2 g, 97%) was iso-
lated as a bright yellow solid, m.p. >3008C; MS (FD, 8 kV): m/z: 1129
[M]+ (calcd for C47H48Br2O2: 1129.01); 1H NMR (300 MHz, [D8]THF,
3
298 K): d=7.73 (d, J(H,H)=8.4 Hz, 4H); 7.34 (s, 1H); 7.55 (s, 1H); 7.32
(d, 3J(H,H)=8.4 Hz, 4H); 7.14 6.70 ppm (m, 38H, Harom); 13C NMR
(75 MHz, [D8]THF, 298 K): d=194.51 (C=O), 149.62 (q), 143.89 (q),
142.62 (q), 142.53 (q), 142.41 (q), 142.15 (q), 141.49 (q), 141.08 (q),
1412
¹ 2004 Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 1398 1414

Dendritic Multichromophores
1398 1414
1074, 1176, 1357, 1498, 1590, 1664, 1702, 2869, 2962, 3025, 3054 cmÀ1; ele-
mental analysis (%) calcd for C338H242N6O16: C 87.42, H 5.25, N 1.81;
found: C 87.33, H 5.14, N 1.79.
142.22 (q), 141.58 (q), 141.44 (q), 141.13 (q), 140.81 (q), 140.65 (q),
140.40 (q), 140.17 (q), 139.61 (q), 138.74 (q), 138.68 (q), 138.49 (q),
133.93 (q), 133.29 (t), 132.97 (t), 132.80 (t), 132.62 (t), 131.93 (t), 131.23
(t), 131.07 (t), 130.54 (q), 130.25 (t), 129.95 (t), 129.69 (t), 129.66 (t),
129.47 (q), 128.93 (t), 128.47 (t), 128.21 (t), 128.06 (q), 127.69 (t), 127.20
(t), 126.65 (q), 125.21 (t), 124.80 (t), 124.59 (t), 123.85 (q), 122.48 (q),
122.35 (q), 121.65 (t), 121.45 (t), 121.26 (q), 120.99 (q), 120.03 (t), 84.81
30: Compounds 10 (30 mg, 0.023 mmol) and 14 (389 mg, 0.185 mmol)
were dissolved in o-xylene (3 mL) and diphenyl ether (3 mL) and heated
under inert conditions for 48 h at 1908C.After the mixture had been al-
lowed to cool, the crude product was dissolved in dichloromethane and
precipitated in methanol (50 mL).The precipitate was filtered, dried, and
purified by column chromatography with dichloromethane and then with
acetone, as for 29.By using THF as eluent, 30 (183 mg, 83%) was isolat-
(q,
C ethynyl), 79.15 (CH ethynyl), 78.97 (CH ethynyl), 30.20 (t,
CH(CH3)2), 24.68 (t, CH(CH3)2), 24.61 (t, CH(CH3)2) ppm; IR (KBr
pellet): n˜ =2921 (s), 2850 (s), 1702, 1660, 1589, 1504, 1463, 1328, 1278,
1207 cmÀ1; elemental analysis (%) calcd for C364H242N6O16: C 87.68, H
5.15, N 1.77; found: C 87.51, H 5.11, N 1.76.
ed as
a violet solid, m.p. >3008C; MALDI-TOF MS: m/z: 9703
[M+Ag]+ (calcd for C714H502N10O24 =9594.01); 1H NMR (500 MHz,
C2D2Cl4, 353 K): d=9.39 (s, 4H), 8.55 8.52 (m, 48H), 8.18 (s, 4H), 7.54
7.57 (m, 306H), 2.69 (m, 20H), 1.11 ppm (d, 3J(H,H)=6.1 Hz, 120H);
13C NMR (500 MHz, [D2]C2H2Cl4, 353 K): d=164.03 (C=O), 146.06 (q),
143.84 (q, br), 142.16 (q), 142.05 (q), 141.70 (q), 141.54 (q), 141.11 (q),
140.93 (q), 140.82 (q), 140.70 (q), 140.42 (q), 140.21 (q), 139.94 (q),
139.69 (q), 138.58 (q), 137.94 (q), 136.99 (q), 136.71 (q), 133.11 (q),
132.07 (t, br), 131.69 (q), 131.36 (t), 130.78 (q), 130.38 (q), 130.24 (t),
130.23 (t), 129.57 (q), 129.35 (t), 128.69 (t), 128.52 (q, br), 128.38 (t),
128.14 (t), 128.07 (t), 127.87 (t), 127.19 (t), 127.10 (t), 126.88 (t), 126.51
(t), 125.85 (t), 124.11 (t), 123.66 (t), 121.38 (q), 121.25 (q), 120.60 (t),
120.34 (t), 29.70 (t, CHCH3), 24.22 ppm (t, CHCH3); UV/Vis (CHCl3):
lmax (e)=509 (258150), 526 (251611), 675 nm (85413mÀ1 cmÀ1); IR (KBr
pellet): n˜ =700, 754, 811, 840, 931, 1074, 1176, 1357, 1498, 1590, 1664,
1702, 2869, 2962, 3025, 3054 cmÀ1; elemental analysis (%) calcd for
C714H502N10O24: C 89.28, H 5.27, N 1.46; found: C 88.73, H 5.02, N 1.35.
32: Compounds 31b (30 mg, 0.0063 mmol) and 13 (187 mg, 0.101 mmol)
were dissolved in o-xylene (3 mL) and diphenyl ether (3 mL) and heated
under inert conditions for 3 4 days at 1908C.After the mixture had been
allowed to cool, the crude product was dissolved in dichloromethane and
precipitated in methanol.The precipitate was filtered, dried, and purified
by column chromatography with dichloromethane and then with acetone,
as described above for 29.By using THF as eluent, 32 (48 mg, 63%) was
isolated as a dark solid, m.p. >3008C; MALDI-TOF MS: m/z: 12165
[M+Ag]+ (calcd for C42H40Si: 12053); 1H NMR (500 MHz, [D8]THF,
298 K): d=9.53 (s, 4H), 8.68 8.55 (m, 40H), 8.23 (s, 4H), 7.87 (m, 8H)*,
7.79 (m, 8H)*, 7.68 6.52 (m, 390H), 2.75 (m, 28H), 1.10 ppm (m, 168H);
13C NMR (125 MHz, [D8]THF, 324 K): d=164.93 (C=O), 164.72 (C=O),
164.64 (C=O), 163.82 (q), 156.24 (q), 156.17 (q), 155.55 (q), 148.19 (q),
148.12 (q), 144.49 (q), 143.28 (q), 143.13 (q), 143.02 (q), 142.93 (q),
142.87 (q), 142.80 (q), 142,78 (q), 142.72 (q), 142.68 (q), 142.58 (q),
142.49 (q), 142.34 (q), 142.29 (q), 142.11 (q), 141.89 (q), 141.79 (q),
141.52 (q), 141.44 (q), 141.38 (q), 141.32 (q), 141.09 (q), 140.86 (q),
140.61 (q), 140.51 (q), 140.41 (q), 140.15 (q), 140.09 (q), 139.74 (q,
broad), 138.77 (q), 138.64 (q), 138.38 (q), 137.52 (q), 137.25 (q), 134.10
(q), 133.65 (q), 133.56 (q), 133.10 (t), 132.88 (t), 132.68 (t), 132.36 (t),
132.10 (t), 131.83 (t), 131.70 (t), 131.19 (t), 131.06 (t), 130.85 (q), 130.73
(q), 130.63 (q), 130.40 (t), 130.22 (q), 130.11 (q), 129.95 (t), 129.60,
129.49, 129.19 (t), 128.78 (t), 128.68 (t), 128.55, 128.45, 128.38, 128.20,
128.09 (t, br), 127.81 (t, br), 127.52 (q), 127.39 (q), 127. 30 (q), 126.84,
126.54, 125.17, 124.78, 124 59 (t), 124.48 (t), 123.91, 123.34 (q), 123.31 (q),
122.69 (q, br), 122.63 (q), 122.58 (q), 121.76, 121.59, 121.51 (q), 120.03 (q,
br), 30.29 (t, CH(CH3)2), 24.66 (t, CH(CH3)2), 24.56 (t, CH(CH3)2),
24.48 ppm (t, br, CH(CH3)2); UV/Vis (CHCl3): lmax (e)=371 (182163)
509 (138112), 527 (141218), 677 nm (98578mÀ1 cmÀ1); IR (KBr pellet):
n˜ =700, 754, 811, 840, 931, 1074, 1176, 1357, 1498, 1590, 1664, 1702, 2869,
2962, 3025, 3054 cmÀ1; elemental analysis (%) calcd for C890H650N14O32: C
88.69, H 5.44, N 1.63; found: C 87.97, H 5.24, N 1.51. * Signals not re-
solved.
31a: Compounds 10 (40 mg, 0.031 mmol) and 12 (150 mg, 0.174 mmol)
were dissolved in o-xylene (2 mL) under inert conditions and heated for
12 h at 1708C.After the mixture had been allowed to cool, the crude
product was dissolved in dichloromethane and precipitated in methanol
(50 mL).The precipitate was collected by filtration, dried, and purified
by column chromatography with dichloromethane and then with acetone
as described above for 29.By using THF as eluent, 31a (159 mg, 90%)
was isolated as a violet solid; m.p. >3008C; MALDI-TOF MS: m/z:
5365 [M]+ (calcd for C381H318N6O16Si4: 5365.20); 1H NMR (500 MHz,
[D8]THF, 298 K): d=9.51 (s, 4H), 8.54 (brm, 24H), 8.23 (s, 4H), 7.71 (s,
2H), 7.69 (s, 2H), 7.60 6.91 (m, 118H), 2.80 (m, 12H), 1.16 (m, 72H),
1.05 ppm (d, 3J=6.7 Hz, 84H); 13C NMR (125 MHz, [D8]THF, 298 K):
d=164.61 (q), 163.81 (q), 156.09 (q), 155.61 (q), 147.13 (q), 144.19 (q),
142.83 (q), 142.71 (q), 142.61 (q), 142.52 (q), 142.36 (q), 142.29 (q),
142.22 (q), 141.58 (q), 141.44 (q), 141.13 (q), 140.81 (q), 140.65 (q),
140.40 (q), 140.17 (q), 139.61 (q), 138.74 (q), 138.68 (q), 138.49 (q),
133.93 (q), 133.29 (t), 132.97 (t), 132.80 (t), 132.62 (t), 131.93 (t), 131.23
(t), 131.07 (t), 130.54 (q), 130.25 (t), 129.95 (t), 129.69 (t), 129.66 (t),
129.47 (q), 128.93 (t), 128.47 (t), 128.21 (t), 128.06 (q), 127.69 (t), 127.20
(t), 126.65 (q), 125.21 (t), 124.80 (t), 124.59 (t), 123.85 (q), 122.48 (q),
122.35 (q), 121.65 (t), 121.45 (t), 121.26 (q), 120.99 (q), 120.03 (t), 84.81
(q,
C ethynyl), 79.15 (CH ethynyl), 78.97 (CH ethynyl), 30.20 (t,
Acknowledgment
CH(CH3)2), 24.68 (t, CH(CH3)2), 24.61 (t, CH(CH3)2), 18.57 (CH TiPS),
13.79 ppm (CH3 TiPS); IR (KBr pellet): n˜ =700, 754, 811, 840, 931, 1074,
1176, 1357, 1498, 1590, 1664, 1702, 2869, 2962, 3025, 3054 cmÀ1; elemental
analysis (%) calcd for C382H322N6O16Si4: C 85.52, H 6.05, N 1.57; found: C
84.98, H 5.83, N 1.45.
This research was supported by the BMBF nano-center, the SFB, and the
European Associated Laboratory (LEA).We thank S.Spang for his sup-
port in the syntheses, and Dr.F.Dˆtz and Dr.M.Baumgarten, who
kindly read the manuscript and made many valuable comments.
31b: Compound 31a (180 mg, 0.0335 mmol) was dissolved in freshly dis-
tilled THF (8 mL) and flushed with argon for 10 min.Then Bu NF¥3H2O
4
(14 mg, 0.0436 mmol) in THF (2 mL) was added by syringe. The reaction
mixture immediately turned dark, and the progress of the reaction was
monitored by TLC with petroleum ether/dichloromethane (1/1).After
5 min, the reaction was finished, and distilled water (20 mL) was added.
Then the crude product was extracted with dichloromethane and washed
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¹ 2004 Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim
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Chem. Eur. J. 2004, 10, 1398 1414