Dendron-functionalized macromolecules: Enhancing core luminescence and tuning carrier injection

Article abstract of DOI:10.1021/ma049754e

A novel series of naphthalimide dendrimers has been synthesized based on a convergent and divergent combined approach. The dendrimers consist of naphthalimide-based cores, Frechet-type poly(aryl ether) dendrons, and carbazole (CZ) or oxadiazole (OXZ) peri

Full text of DOI:10.1021/ma049754e

Macromolecules 2004, 37, 4387-4398
4387
Dendron-Functionalized Macromolecules: Enhancing Core
Luminescence and Tuning Carrier Injection
P a Du ,†, Wei-Hon g Zh u ,†, Yu -Qin g Xie,‡ F ei Zh a o,† Ch ien -F on g Ku ,§ Yon g Ca o,‡
Ch en -P in Ch a n g,§ a n d He Tia n *,†
Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science &
Technology, Shanghai 200237, China, Institute of Polymer Optoelectronic Materials and Devices,
South China University of Technology, Guangzhou 510640, China, and Department of Chemistry,
Fu J en Catholic University, Shin Chung, Taipei 104, China
Received February 4, 2004; Revised Manuscript Received April 2, 2004
ABSTRACT: A novel series of naphthalimide dendrimers has been synthesized based on a convergent
and divergent combined approach. The dendrimers consist of naphthalimide-based cores, Fre´chet-type
poly(aryl ether) dendrons, and carbazole (CZ) or oxadiazole (OXZ) peripheral groups. The higher generation
dendrimer has site-isolation effect, or the dilution effect of the dendrons. This configuration would reduce
the aggregating extent or possibility of the core unit, thus resulting in a relatively small red-shift of
absorption and fluorescent spectra when they form a solid film for the applications. Studies of steady-
state fluorescence properties of the dendrimers show that excitation of the terminal chromophores results
mainly in the core emission alone, as the donor emission is seriously quenched due to its effective Fo¨rster
intramolecular energy transfer to the core. The dendrimers show enhanced luminescence properties of
the core, and the enhanced luminescent efficiency is dependent on the generation number of the
dendrimers. Time-resolved luminescent measurements further supported the conclusion that the
contribution tendency for each peripheral donor is decreased with the increasing of the generation number,
especially for the third generation. The dendron-incorporated carbazole unit can decrease the HOMO
orbital energy by 0.4 eV, thus facilitating the hole-injection in electroluminescent (EL) devices. The
preliminary EL results with a single-layer architecture made with the dendrimers by means of the spin-
coating technique demonstrate that these dendrimers could be utilized as promising active nondoping
emitters.
In tr od u ction
mophores, that is, dendrons act as the “molecular lens”.7
For example, Fre´chet et al.8 reported poly(aryl ether)
dendrimers, in which coumarin 2 acts as a light-
harvesting antenna and coumarin 343 as a focal chro-
mophore acceptor. In the phenyl acetylene dendrimers
reported by Moore and co-workers, there is an energy
gradient from the periphery toward the center.9
Research on novel luminescent materials has played
an important role in developing organic light-emitting
diodes (OLEDs). Both small molecules1 and polymers2
have been studied extensively for use in OLEDs. Re-
cently, several research groups have investigated some
well-defined dendrimers as an alternative class of
electroluminescent (EL) materials.3 In contrast to poly-
mers, the beauty of dendrimers is that their size and
architecture can be specifically controlled in their
synthesis.4 The dendritic architecture can be also used
to improve the solubility of luminescent chromophores
to form a uniform film with the spin-coating technique,
thus overcoming the high cost of the vacuum deposition
process.5
A characteristic of dendritic macromolecules is the
presence of numerous peripheral chain ends that all
surround a single core. The globular shape of dendrim-
ers provides a large surface area that can be decorated
with the chromophores, thus resulting in a large ab-
sorption cross section and enabling efficient capture of
photons.6 Furthermore, both the peripheral chro-
mophores and the focal dye (or core) are capable of
contributing the absorption of the entire macromolecule.
In a dendritic antenna, the peripheral donor units
collect photons and transfer the excitation energy
through space to the core or focal point acceptor chro-
Luminescent dendrimers consists of three main
units: the emissive core, the dendrons, and the terminal
or periphery groups. This modular construction enables
the processing and electronic properties to be tuned
independently. Dendrimers provide new opportunities
for precisely placing some charge-carrier transporting
units by the generation in a three-dimensional nano-
scale construction. Despite the impressive scope of
controlling solubility and amorphous form,7 examples
of the design of modulating charge carrier-transporting
dendron-function of a dendrimer for OLED applications
so far are rare. Here we report a novel series of
naphthalimide-based dendrimers (shown in Scheme 1),
into which the dendron periphery group carbazole or
oxadiazole is introduced to design charge carrier trans-
porting tunable type emitters for OLEDs. These dendri-
mers show specific light-antenna capacity and tunable
charge carrier-transporting characteristics. Specifically,
the enhanced emission for the dendrimers were ob-
served comparing with that of a direct-core emission,
that is, light harvest for the luminescence of the
chromophore by the light antenna is more efficient than
direct excitation at the absorption maximum by an
external light source. Time-resolved luminescence mea-
surements have been done for the dendrimers to reveal
the interaction between the donors and the core.
* Corresponding author. E-mail: tianhe@ecust.edu.cn.
† East China University of Science & Technology (ECUST).
‡ South China University of Technology (SCUT).
§ Fu J en Catholic University (FJ U).
These authors contributed equally to this work.
10.1021/ma049754e CCC: $27.50 © 2004 American Chemical Society
Published on Web 05/18/2004

4388 Du et al.
Macromolecules, Vol. 37, No. 12, 2004
Sch em e 1. Ch em ica l Str u ctu r es of Ta r get Den d r im er s a n d th e Refer en ce Com p ou n d s
Resu lts a n d Discu ssion
structed by Fre´chet-type poly(aryl ether) dendrons
(shown in Scheme 1). We chose 1,8-naphthalimide (NP)
as a fluorescent core because of its chemical stability
and high fluorescent efficiency, whose derivatives are
known to be acted as the promise triplet host matrix,10
supramolecular moieties for the study of photoinduced
Design a n d Syn th esis of Ligh t-Em ittin g Den -
d r im er s. To study the properties of site-isolation and
light harvesting, the synthesized dendrimers features
the naphthalimide chromophore at the center of the
dendrimer with a specific functional periphery con-

Macromolecules, Vol. 37, No. 12, 2004
Novel Naphthalimide Dendrimers 4389
Sch em e 2. Syn th etic Rou te of Secon d -Gen er a tion Den d r im er s 4CZ-NP m
Sch em e 3. Attem p t to Syn th esize Ta r get Den d r im er s Usin g both Con ven tion a l Syn th etic Ester P r otocols a n d
Meth od s w ith ou t Tosyla tion Activa tion
electron transfer,11 fluorescence switches,12 liquid crys-
tal displays,13 and EL materials.14 The functional
periphery of the dendrimers is carbazole (CZ) or oxa-
diazole (OXZ) units that can play a major role in charge
carrier-transporting and also act as energy donors (light
antenna) for the core acceptor chromophores. A combi-
nation of divergent and convergent steps, also known
as the double-stage convergent approach,15 can be
specifically developed to synthesize the dendrimers nCZ-
NPm (n ) 2, 4, 8; m ) 1, 2, 3) and nOXZ-NPm (n ) 2,
4; m ) 1, 2, 3). NPm serves as a molecular core unit
that bears two acid groups. Such reactivity polarity is
reversed to the “classical” convergent synthesis of poly-
ether dendrimers originally reported by Hawker and
Fre´chet.16 Coupling two CZ or OXZ units, which will
become the terminal groups, to 3,5-dihydroxybenzyl
alcohol occurred readily in the presence of potassium
carbonate and 18-crown-6 in acetone when heated at
reflux. This gave the first-generation dendron alcohol
(CZ)2-(G-1)-OH or (OXZ)2-(G-1)-OH. To illustrate this
case, the synthesis of 4CZ-NP3 by the convergent
growth approach is shown in Scheme 2. Reaction of 9-(4-
bromobutyl)-9H-carbazole with 3,5-dihydroxybenzyl al-
cohol yielded (CZ)2-(G-1)-OH, followed by tosylation at
ambient temperature to give the second-generation
dendron (CZ)2-(G-1)-OSO2Me. The bromination of the
benzyl alcohol group at the focal point of (CZ)2-(G-1)-
OH by reaction with carbon tetrabromide/triphenylphos-
phine proceeded smoothly to afford the corresponding
bromide (CZ)2-(G-1)-Br. Reaction of 2.1 equiv of (CZ)2-
(G-1)-Br with 3,5-dihydroxybenzyl alcohol gave (CZ)4-
(G-2)-OH, which when reacted with methane sulfonyl
chloride gave the third-generation dendron (CZ)4-(G-2)-
OSO2Me. In the presence of potassium carbonate in
DMF at 100 °C, assembly of the core intermediate with
the corresponding different generation dendrons was
achieved to obtain the final dendrimers. Similarly, we
prepared other target dendrimers.
It should be pointed out that the activation step of
tosylation is very critical to make the coupling possible
and successful. Using conventional synthetic ester
protocols and methods (shown in Scheme 3), attempts
to prepare target dendrimers failed. The dendrons and
the dendrimers were characterized by 1H NMR, 13C
NMR, and FAB or MALDI-TOF mass spectroscopy.
1
With the dendron generation increasing, H NMR and
13C NMR signals become more complicate and difficult
to discern structures. To assess more clearly the identity
of chemical structures, further characterization has
been performed by MALDI-TOF mass spectroscopy,
which has become very valuable for macromolecules
(MW > 1500).7 All of the third generation of dendrimers
show the corresponding ion peaks of M+ + Na and M+
+ K (Figure 1). The charge-state determination for

4390 Du et al.
Macromolecules, Vol. 37, No. 12, 2004
Ta ble 1. Absor p tion a n d F lu or escen ce Em ission Sp ectr a l Da ta in THF a n d Solid F ilm for Ta r get Den d r im er s a n d
Meltin g P oin ts
in THF
(nm) (log ꢀ)
in solid film
dendrimers
mp/°C
λabs
λemmax/nm
ηa (%)
LERb (λex (nm))
λabs
(nm)
λem
(nm)
max
max
max
2OXZ-NP1
2OXZ-NP2
2OXZ-NP3
4OXZ-NP1
4OXZ-NP2
4OXZ-NP3
2CZ-NP1
2CZ-NP2
2CZ-NP3
4CZ-NP1
4CZ-NP2
4CZ-NP3
8CZ-NP1
8CZ-NP2
8CZ-NP3
149-150 295 (4.89), 411 (4.12)
154-155 296(4.92), 400 (4.1)
168-170 296(1.92), 391 (4.09)
196-198 296 (5.26), 411 (4.02)
172-173 296 (5.28), 406 (4.06)
195-196 296 (5.28), 393 (4.14)
355, 514
355, 516
355, 511
355, 514
355, 521
355, 513
351,366, 514
94
88
91
96
98
98
87
92
93
94
95
96
84
89
90
4.8 (295)
5.1 (296)
6.7 (296)
11.9 (296)
12 (296)
317, 436
318, 421
318, 415
315, 424
314, 410
319, 400
542
537
527
534
527
537
534
522
537
531
519
528
531
518
16.3 (296)
136-137 330 (4.09), 345 (4.15) 411 (4.17)
3.6 (330), 3.5 (345) 333, 432, 348
3.6 (330), 3.3 (345) 333, 424, 348
2.8 (330), 2.4 (345) 333, 418, 348
5.8 (330), 5.7 (345) 333, 426, 348
5.4 (330), 5.0 (345) 333, 413, 348
5.4 (330), 4.2 (345) 333, 406, 348
5.7 (330), 5.6 (345) 333, 426, 348
5.0 (330), 4.4 (345) 333, 413, 348
5.4 (330), 4.0 (345) 333, 405, 348
136-138 330 (4.14), 345 (4.20), 406 (4.24) 351,366, 521
150-151 330 (4.0), 345 (4.11), 393 (4.06)
144-145 330 (4.26), 345 (4.34) 411 (4.11)
139-140 330 (4.37), 345 (4.33) 406 (4.19)
351,366, 513
351, 366, 514
351, 366, 521
194-195 330 (4.29), 345 (4.36), 393 (4.11) 351, 366, 513
107-109 330 (4.49), 345 (4.53), 411 (3.94) 351, 366, 514
115-117 330 (4.45), 345 (4.51), 406 (4.01) 351, 366, 521
116-118 330 (4.46), 345 (4.53), 393 (4.0)
351, 366, 513
a
Peripheral donor emission quenching efficiency (η) was calculated by comparing the integration of donor emission between the simple
mixture and the target dendrimer excited at corresponding donor absorption peak when these two spectra are normalized at the λmax
b
value of the core chromophore. The core luminescence enhancing ratio (LER) was calculated by comparing the integration of acceptor
emission between the simple mixture and the target dendrimer excited at corresponding donor absorption peak when these two spectra
are normalized at the λmax value of the core chromophore.
F igu r e 2. Absorption spectra of 8CZ-NP3, 4CZ-NP3, and 2CZ-
NP3 in THF (2.4 × 10-5 mol‚L-1), normalized at the absorption
peak of naphthalimide unit.
F igu r e 1. MALDI-TOF mass spectra of dendrimers 8CZ-NP1
(top) and 8CZ-NP3 (bottom).
isotropic distributions with peak separation of 1.0 was
performed by high-resolution scan experiments. A peak
at m/z 2930.42 for 8CZ-NP1 ascribed to M+ + Na has
been observed. Another centered at 2946.39 with higher
abundance for 8CZ-NP1 corresponds to M+ + K.
Ligh t-Ha r vestin g a n d En h a n ced Lu m in escen ce
P r op er ties. The absorption and emission spectral data
of the dendrimers are listed in Table 1. In THF, the
absorption peaks at about 330 and 345 nm are at-
tributed to the absorption of the carbazole moiety; the
F igu r e 3. Normalized absorption spectra of 2CZ-NP3, 4CZ-
NP3, and 8CZ-NP3 in solid film. Note: the absorbance of
carbazole unit disproportional to the generation and the
absorption peak at 296 nm is attributed to the OXZ
moiety. The absorption peaks characterized for naph-
thalimide unit NP1, NP2, and NP3 are located at 411,
number of carbazole is attributed to the thickness difference
406, and 393 nm, respectively. The dendrimers nCZ-
NPm (n ) 2, 4, 8) show very similar absorption
characteristics in THF, as shown in Figure 2. In solid
neat film, the CZ moiety of 2CZ-NPm, 4CZ-NPm, and
8CZ-NPm also shows similar absorption characteristics
(Figure 3). In contrast to the absorption in the solution,
the absorption of core chromophores NP1, NP2, and
NP3 in solid film shifts bathochromically due to the
aggregation effect. However, the red-shift in the absorp-
of the inhomogeneous film samples.
tion spectra is greatly dependent on the dendrimer
generation number. For instance, compared with their
absorption in the solution, the absorption red shifts of
2CZ-NP3, 4CZ-NP3, and 8CZ-NP3 are 25, 13, and 12
nm, respectively. It can be concluded that the higher
generation dendrimer has a site-isolation effect or a
dilution effect due to the dendrons. This configuration

Macromolecules, Vol. 37, No. 12, 2004
Novel Naphthalimide Dendrimers 4391
F igu r e 6. Absorption spectra of compounds 2CZ-NP1 (curve
F igu r e 4. Emission spectra of 4CZ-NP3 in THF (2.4 × 10-5
mol‚L-1) at excitation of (a) the dendrimer periphery CZ (330
nm), (b) the dendrimer periphery CZ (345 nm), and (c) the core
(393 nm). The relative fluorescent intensities for the core: 1.16,
1.20, and 1.00, respectively.
a), 2CZ-NP2 (curve b), and 2CZ-NP3 (curve c) and emission
spectra of (CZ)2-(G-1)-OH (curve d) in THF (2.4 × 10-5 mol‚L-1
)
excited at 330 nm. It indicates that there exists an overlap
between the emission band of the donor and the absorption
band of the acceptor, resulting in Fo¨rster energy transfer
(FRET) occurring from a carbazole unit to the core naphthal-
imide.
F igu r e 5. Emission spectra of 4OXZ-NP3 in THF (3.0 × 10-6
mol‚L-1) at the excitation of (a) the dendrimer periphery OXZ
(296 nm) and (b) the core (393 nm). The relative fluorescent
intensities for the core are 3.9 and 1.0, respectively.
F igu r e 7. Emission spectra in THF (2.4 × 10-5 mol‚L-1) of
(a) 8CZ-NP3, (b) 4CZ-NP3, (c) 2CZ-NP3, and (d) a simple
mixture of (CZ)2-(G-1)-OH and NP3 (molar ratio ) 2:1) at an
excitation of 345 nm.
would reduce the aggregating extent or possibility of the
core unit, thus resulting in a relatively small red-shift
of absorption and fluorescent spectra when the solid film
is formed for the applications.
The light harvesting and the enhanced luminescence
properties of the core might be explained by the interac-
tion between the core chromophore and the terminal
groups. The excitation spectra of the dendrimers clearly
indicate that the fluorescence of the core naphthalimide
unit results not only from the contribution of itself but
also from that of the peripheral carbazole or oxadiazole
units. The optical properties of each interactive compo-
nent are illustrated using first-generation dendrimers
2CZ-NP1, 2CZ-NP2, 2CZ-NP3, and (CZ)2-(G-1)-OH (as
shown in Figure 6), and there exists an overlap between
the emission band of the donor and the absorption band
of the acceptor, thus creating a pathway for Fo¨rster
resonance energy transfer (FRET) to occur from the
carbazole unit to the core naphthalimide. Figure 7
shows the relative emission intensity for different
generation dendrimers 2CZ-NP3, 4CZ-NP3, and 8CZ-
NP3 when excited at 345 nm. Comparing with that of
the simple mixture containing peripheral donor and the
core dye, the core emission of all dendrimers increased.
The fluorescent intensity of 4CZ-NP3 is strongest, where
a 4.2-fold increase in the core emission relative to the
emission of the core lacking the peripheral donors, a 4.0-
fold increase in the core emission in 8CZ-NP3, and a
2.4-fold enhancement of the core emission in 2CZ-NP3
were observed. The emission of the donor CZ was
drastically decreased, and the fluorescent quenching
Dendrimers have an ideal architecture to study the
interaction between the chromophores. The reference
carbazole that lacks the acceptor focal dye shows two
strong emission peaks at 351 and 363 nm excited at 330
nm. However, the excitation of the peripheral donor
units (carbazole or oxadiazole) of the dendrimers in this
work mainly results in the fluorescence of the core dye
alone (Figures 4 and 5). Actually, the emission intensity
of the core for 4CZ-NP3 excited at peripheral group (345
nm) is about 20% higher than that of the direct core
excitation (393 nm). Similarly as shown in Figure 5, the
emission intensity of the core for 4OXZ-NP3 excited at
the peripheral group (296 nm) is 3.9 times higher than
that of the direct core excitation (393 nm). The intensity
of the harvested emission for the dendrimers synthe-
sized in this work is stronger than that of the direct-
core emission; that is, light harvest for the luminescence
of the chromophore by the light antenna is more efficient
than direct excitation at the absorption maximum by
an external light source.17 A similar effect has already
been described for coumarin-labeled dendrimers18 as
well as for phenyl acetylene dendrimers that bear a focal
perylene chromophore.19

4392 Du et al.
Macromolecules, Vol. 37, No. 12, 2004
Ta ble 2. F lu or escen ce Lifetim es of 4CZ-NP 3 (λem ) 350
n m ) Obta in ed fr om th e Tr a n sien t Deca y a ga in st th e
Con cen tr a tion Va r ia tion of TiO2 Excited a t th e
Absor p tion P ea k of th e CZ (330 n m )
lifetime τ (ns)
(component ratio (%))
compound (concn (mol‚L-1))
4CZ-NP3 (1.0 × 10-5
)
0.31 (53.86) 7.71 (46.14)
0.69 (73.00) 8.22 (27.00)
0.60 (100)
0.59 (100)
0.73 (100)
4CZ-NP3 (1.0 × 10-5) + TiO2 (1.0 × 10-5
4CZ-NP3 (1.0 × 10-5) + TiO2 (3.0 × 10-5
4CZ-NP3 (1.0 × 10-5) + TiO2 (6.0 × 10-5
4CZ-NP3 (1.0 × 10-5) + TiO2 (9.0 × 10-5
4CZ-NP3 (1.0 × 10-5) + TiO2 (1.2 × 10-4
4CZ-NP3 (1.0 × 10-5) + TiO2 (1.5 × 10-4
)
)
)
)
)
)
0.54 (100)
0.59 (100)
Ta ble 3. F lu or escen ce Lifetim e of 8CZ-NP 3 (λem ) 350 n m )
Obta in ed fr om th e Tr a n sien t Deca y a ga in st th e
Con cen tr a tion Va r ia tion of TiO2 Excited a t th e
Absor p tion P ea k of th e CZ (330 n m )
F igu r e 8. Fluorescence decay profiles of the compounds in
THF (1 × 10-5 mol‚L-1): (a) CZ, (b) 8CZ-NP3, and (c) 4CZ-
NP3 at 350 nm upon excitation at 345 nm.
lifetime τ (ns)
(component ratio (%))
compound (concn (mol‚L-1))
reached higher than 84%. If one considers the number
of peripheral donors in different generation dendrimers,
the core luminescence-enhancing ratio for the contribu-
tion of each donor CZ unit in 2CZ-NP3, 4CZ-NP3, and
8CZ-NP3 is 1.2, 1.04 and 0.5, respectively. It can be
demonstrated that the energy transfer efficiency is
highly dependent on the dendrimer generation number.
That is, with the dendrimer generation number increas-
ing, the contribution tendency of each CZ unit for the
core luminescence enhancement decreased, especially
for the third generation. This might be explained in
terms of the Fo¨rster mechanism. Since Fo¨rster transfer
is a resonant dipole coupling process that transfers
energy between singlet states and conserves the spin
state of the donor and the acceptor chromophores,20 it
is known that the efficiency of Fo¨rster energy transfer
decreases as the inverse sixth power dependence on the
donor-acceptor separation. Generally, the higher the
number of donor peripheral groups that surround the
core, the larger the cross-section for energy collection.
However, the average distance between the core and the
peripheral donor groups also increases as the generation
number increases. Therefore, dendrimer generation
number determines the Fo¨rster energy transfer ef-
ficiency of the donor CZ to the core. The luminescence-
enhancing ratios of other dendrimers are summarized
in Table 1 and show a very similar tendency.
8CZ-NP3 (1.0 × 10-5
)
0.53 (22.55) 7.82 (77.45)
1.03 (31.62) 7.89 (68.38)
1.31 (41.18) 7.51 (58.82)
1.49 (53.78) 8.29 (46.22)
1.22 (61.85) 8.35 (38.15)
1.68 (66.71) 9.38 (33.29)
1.12 (68.92) 8.19 (31.08)
8CZ-NP3 (1.0 × 10-5) + TiO2 (1.0 × 10-5
8CZ-NP3 (1.0 × 10-5) + TiO2 (3.0 × 10-5
8CZ-NP3 (1.0 × 10-5) + TiO2 (6.0 × 10-5
8CZ-NP3 (1.0 × 10-5) + TiO2 (9.0 × 10-5
8CZ-NP3 (1.0 × 10-5) + TiO2 (1.2 × 10-4
8CZ-NP3 (1.0 × 10-5) + TiO2 (1.5 × 10-4
)
)
)
)
)
)
NP3, the CZ unit has two components with fluorescent
lifetimes of 0.314 ns (53.86%) and 7.713 ns (46.14%).
8CZ-NP3 shows two character fluorescent lifetimes for
the CZ unit with 0.533 ns (22.55%) and 7.818 ns
(77.45%). The relatively short-lived fluorescent lifetimes
can be assignable to the residual component after the
photochemical communication between CZ units and
naphthalimide cores. Comparing the shorter lifetime
components of the second-generation dendrimer 4CZ-
NP3 (0.314 ns) and the third-generation dendrimer 8CZ-
NP3 (0.553 ns), the fluorescence of the CZ unit in 4CZ-
NP3 is more obviously quenched due to the effective
intramolecular energy transfer and the photoinduced
electron transfer to the core. From the semiempirical
simulation of hyperchemistry, the average rate constant
(k ) 1/τD(R0/R1)6) for the fluorescence decay became
smaller as the CZ units increased from 4CZ-NP3 (2.42
ns-1) to 8CZ-NP3 (1.3 ns-1), which is almost consistent
with the core luminescence-enhancing ratio for each
donor contribution.
It should be pointed that the intramolecular energy
transfer efficiency in dendrimer system is much higher
than that of an intermolecular energy transfer in the
simple mixture of the core and the peripherals. The
obvious fluorescence quenching of the donor CZ in
dendrimers is shown in Figure 7. This conclusion is
further supported by the dependence of the fluorescence
on the solution concentrations. The fluorescence of the
simple mixture is much more significantly dependent
on the concentration than that for the corresponding
dendrimers. Indeed, for a diluted mixture almost no
fluorescent quenching of the CZ chromophore was
observed, which indicates the less effective intermo-
lecular energy transfer process in the mixture.
It is well-known that TiO2 nanoparticle can be utilized
21
as a “trap” for photoinduced electrons.
When nano-
particle TiO2 was added to the solution of 4CZ-NP3 and
8CZ-NP3 in THF, it can be expected that the interaction
between the core NP and the peripheral CZ would be
disturbed, thus monitoring the mechanism of light-
harvesting in the dendrimers. In fact, with increasing
concentration of TiO2, the content percentage of the
relatively short-lived component characterized for the
CZ unit in 4CZ-NP3 and 8CZ-NP3 increased (Tables 2
and 3). In particular, when the concentration of TiO2
reached 3 × 10-5 mol‚L-1, 4CZ-NP3 exhibits only single
short-live component fluorescence at 350 nm, the long-
live component is disappeared due to the electron
trapping by nanoparticle TiO2. This indicates an ef-
ficient electron transfer between TiO2 nanoparticles and
the CZ units of the dendrimers. In this case the
intramolecular interaction between the core NP and the
peripheral CZ units is efficiently inhibited. The interac-
tion between the peripheral CZ units and TiO2 is
dominated, which decreases the light-antenna effect
Photoinduced electron transfer between the core and
peripheral units might also take place, which should be
further studied by transient fluorescence spectra. The
reference compound carbazole exhibits only a single-
exponential decay with a fluorescent lifetime of 8.401
ns (Figure 8). In contrast, the carbazole units CZ in
dendrimers 4CZ-NP3 and 8CZ-NP3 have dual-exponen-
tial decay characteristics (Figure 8). That is, for 4CZ-

Macromolecules, Vol. 37, No. 12, 2004
Novel Naphthalimide Dendrimers 4393
Ta ble 4. Oxid a tion P oten tia ls a n d Ca lcu la ted HOMO a n d
LUMO En er gies for th e Den d r im er sa
E
ox (V vs reference
HOMO
(eV)
LUMO
(eV)
compounds
electrode Ag/AgCl)
2OXZ-NP1
4OXZ-NP1
2OXZ-NP2
4OXZ-NP2
2OXZ-NP3
4OXZ-NP3
2CZ-NP1
4CZ-NP1
8CZ-NP1
2CZ-NP2
4CZ-NP2
8CZ-NP2
2CZ-NP3
4CZ-NP3
8CZ-NP3
1.24
1.24
1.34
1.34
1.39
1.39
0.90
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
-5.52
-5.52
-5.62
-5.62
-5.67
-5.67
-5.18
-5.21
-5.21
-5.21
-5.21
-5.21
-5.21
-5.21
-5.21
-3.04
-3.04
-3.01
-3.01
-2.97
-2.97
-3.04
-3.04
-3.04
-3.01
-3.01
-3.01
-2.97
-2.97
-2.97
F igu r e 9. Emission spectra of 4CZ-NP3 in THF (1 × 10-5
mol‚L-1) plotted against different concentrations of TiO2
excited at the absorption peak of carbazole (330 nm).
a
between the CZ units and the core naphthalimide
chromophore, as shown in Figure 9.
The oxidative potential of reference ferrocene (Fc) vs reference
electrode Ag/AgCl is 0.52 V.
Electr och em ica l P r op er ties. Cyclic voltammetry
measurements were carried out at a platinum electrode
using millimolar solutions in CH2Cl2 containing 0.1 M
of the support electrolyte, tetrabutylammonium per-
chloride, in a three-electrode cell and potentiostat
assembly. For the dendrimers with carbazole peripheral
groups, the oxidative sweep is predominated by two
reversible peaks originated from the carbazole unit
appeared at 0.93 and 1.24 V (shown in Figure 10), with
which an irreversible peak of the naphthalimide unit
located between 1.10 and 1.30 V is overlapped. While
for the dendrimers with oxadiazole peripheral groups,
only an irreversible peak in oxidative scan arises from
the naphthalimide unit. The HOMO energy values for
the dendrimers were calculated according to the value
of -4.8 eV for ferrocene (Fc) with respect to zero vacuum
level. And the optical edge was utilized to derive the
band gap and give the LUMO energy values for the
dendrimers.22 The measured oxidation potentials (vs
reference electrode Ag/AgCl) and HOMO and LUMO
energy values for dendrimers are summarized in Table
4. It should be noted that the shell effect does not
distinctly occur, such as redox wave broadening or
shift,23 which can be attributed to the fact that the
dendrimers synthesized in this work are not global
shape.
Th er m a l Sta bility. Starburst compounds and den-
drimers are capable of preventing spatial reorientation
of the molecules, thus eliminating the recrystallization
tendency and favoring the formation of a stable amor-
phous state. This molecular design strategy had been
successfully applied to develop triarylamine-based hole-
transporting materials.24 For the dendrimers in this
study, the second-generation dendrimers have a higher
melting point than those of the first- and third-genera-
tion dendrimers (Table 1). For instance, careful exami-
nation of DSC thermograms for 4CZ-NP3 revealed that
F igu r e 10. Cyclic voltammogram in CH2Cl2: (a) 2CZ-NP1, (b) 4CZ-NP1, (c) 8CZ-NP1, and (d) reference carbazole.

4394 Du et al.
Macromolecules, Vol. 37, No. 12, 2004
Ta ble 5. EL Device P er for m a n ces of 2CZ-NP 3 a n d 8CZ-NP 3
bias
(V)
current
(mA)
luminance
(cd/m2)
eff
(%)
EL peak
(λmax/nm)
EL device structure
ITO//PEDOT(65 nm)//2CZ-NP3(120 nm)//Ba (4 nm) /Al (150 nm)
ITO//PEDOT(65 nm)//8CZ-NP3(80 nm)//Ba (4 nm) /Al (150 nm)
12.48
11.7
15.30
3.12
7.73
5.01
41.94
5.35
308
190
59
0.50
0.48
0.02
0.01
526
526
5
F igu r e 11. EL spectrum and luminance-efficiency-voltage
characteristics of the device ITO//PEDOT(65 nm)//2CZ-NP3-
(120 nm)//Ba (4 nm)/Al (150 nm).
F igu r e 12. EL spectrum and luminance-efficiency-voltage
characteristics of device and ITO//PEDOT(65 nm)//8CZ-NP3
(80 nm)//Ba (4 nm)/Al (150 nm).
there is no distinct glass transition state below 180 °C
(shown in Figure S-1 of the Supporting Information).
When the sample was cooled under rate of 10 °C /min
from 180 to 50 °C, no distinct crystallization phase was
observed. The glass transition temperatures (Tg) of
2OXZ-NP3 and 4OXZ-NP2 are located at 139 and 102
°C, respectively. No distinct glass transition state was
observed for them when taken on the second heating.
Thus, thermal analysis results indicate that such den-
dron-functionalized luminescent materials have good
thermal stability, which is very essential for fabricating
stable organic EL devices.
by 0.4 eV (Table 5), which reduces the hole-injecting
barrier and thus facilitates the hole injection from ITO
electrode. Electrons are injected from the cathode to the
LUMO orbital of the naphthalimide moiety with high
electron affinity (about 3.0 eV) and holes are also
injected from ITO (4.6 eV) to the HOMO orbital of the
carbazole moiety (5.2 eV). Then the holes are transferred
to HOMO orbital of the naphthalimide (ca. 5.5 eV).
Hence, the holes and electrons are trapped in the
naphthalimide moiety to form exciton that undergoes
radiative decay resulting in the naphthalimide charac-
teristic emission.
Electr olu m in escen t P r op er ties. The main objec-
tive of this study is to develop novel dendron-function-
alized luminescent materials. For the preliminary stud-
ies in light-emitting devices, a dendrimer acting as an
active single-layer luminescent material was utilized
(ITO//PEDOT(65 nm)//dendrimers//Ba (4 nm)/Al (150
nm)). Preliminary results of EL devices made with these
dendrimers are listed in Table 5. In both EL devices,
only the emission peak at 526 nm was detected (Figures
11 and 12). Compared with the PL spectrum of the
dendrimers in solid film, the EL spectra are similar to
the PL spectra of corresponding dendrimers, which
indicates the same band gap involved in the EL and the
PL spectra. The peripheral of carbazole unit did not emit
light in the operation of the devices. It is believed that
the carbazole unit decreases the HOMO orbital energy
Con clu sion s
We have synthesized three generations of a novel
series of dendrimers that contain naphthalimide cores,
Fre´chet-type poly(aryl ether) dendrons, and functional
peripheral groups such as carbazole or oxadiazole units
to improve the charge carrier-transporting property for
the application in OLEDs. This modular construction
enables the processing and electronic properties to be
tuned independently. This is a significant advantage
over polymeric or molecular materials where attempts
to tune the solubility often lead to an undesirable
change in the emission properties. We have demon-
strated the fact that the peripheral chromophores CZ
or OXZ have specific light-antenna and enhanced core

Macromolecules, Vol. 37, No. 12, 2004
Novel Naphthalimide Dendrimers 4395
dryness under reduced pressure. The residue was partitioned
between CH2Cl2 and water, and the aqueous layer was
extracted with CH2Cl2 (40 mL × 3). The combined extracts
were dried with anhydrous MgSO4 and evaporated. The
product was purified by column chromatography on silica gel
eluting with CH2Cl2 to give 4 as pale yellow powder (3.44 g,
yield 82.8%). Mp: 118-120 °C. 1H NMR (500 MHz, CDCl3,
ppm): δ ) 1.8 (m, 4 H, -CH2), 2.1 (m, 4 H, -CH2), 3.85 (t, J
) 6.1 Hz, 4 H, -NCH2-), 4.37 (t, J ) 7.1 Hz, 4 H, -OCH2-),
4.7 (s, -CH2OH, 2 H), 6.25 (s, 1 H, Ph-H), 6.5 (s, 2 H, Ph-
H), 7.2 (t × d, J ) 6.8 Hz, J ) 1.0 Hz, 4 H, Ph-H(CZ)), 7.4 (d,
J ) 8.0 Hz, 4 H, Ph-H(CZ)), 7.48 (t × d, J ) 7.9 Hz, J ) 1.0
Hz, 4 H, Ph-H(CZ)), 8.2 (d, J ) 7.8 Hz, 4 H, Ph-H(CZ)).
(CZ)2-(G-1)-OSO2Me (5) (Meth a n esu lfon ic Acid 3,5-Bis-
(4-ca r ba zol-9-yl-bu tyloxy)ben zyl Ester ). A solution of com-
pound 4 (3.1 g, 1.43 mmol) in anhydrous CH2Cl2 (20 mL) was
stirred at room temperature. MeSO2Cl (0.162 g, 1.43 mmol)
and triethylamine (0.144 g, 1.43 mmol) were added dropwise
to the solution and stirred for 24 h. Then water was added to
the solution. The aqueous layer was extracted with CH2Cl2
(40 mL × 3). The extract was dried with anhydrous MgSO4
and evaporated. The product was purified by column chroma-
tography eluting on silica gel with CH2Cl2 to give a white
powder (1.01 g, yield 94%). Mp: 148-149 °C. 1H NMR (500
MHz, CDCl3, ppm): δ ) 1.8 (m, 4 H, -CH2), 1.6 (s, 3 H, -CH3),
2.1 (m, 4 H, -CH2), 3.85 (t, 4 H, J ) 6.0 Hz, -NCH2-), 4.37
(t, J ) 7.1 Hz, 4 H, -OCH2-), 4.5 (s, 2 H, -CH2OSO2Me),
6.30 (s, 1 H, Ph-H), 6.45 (s, 2 H, Ph-H), 7.2 (t, 4 H, Ph-
H(CZ), J ) 7.3 Hz), 7.4 (d, 4 H, Ph-H(CZ), J ) 8.0 Hz), 7.48
(t × d, 4 H, Ph-H(CZ), J ) 7.8 Hz, J ) 1.0 Hz), 8.2 (d, 4 H,
Ph-H(CZ), J ) 8 Hz).
(OXZ)2-(G-1)-OH (6) ((3,5-Bis-{4-[5-(4-ter t-bu tyl-p h en -
yl)-[1,3,4]oxa d ia zol-2-yl]ben zyloxy}p h en yl)m eth a n ol). A
mixture of 2-(4-bromomethyl-phenyl)-5-(4-tert-butyl-phenyl)-
[1,3,4]oxadiazole (OXZ-Br, 5.4 g, 14.5 mmol), 3,5-dihydroxy-
benzyl alcohol (1.0 g, 7.1 mmol), potassium carbonate (3.4 g,
60 mmol), and 18-crown-6 (0.38 g, 1.42 mmol) in anhydrous
acetone (50 mL) was heated at reflux and stirred vigorously
under nitrogen for 56 h. The mixture was allowed to cool and
evaporated to dryness under reduced pressure. The residue
was partitioned between CH2Cl2 and water, and the aqueous
layer was extracted with CH2Cl2 (40 mL × 3). The combined
extracts were dried with anhydrous MgSO4 and evaporated.
The product was purified by column chromatography on silica
gel eluting with CH2Cl2 to give 6 as a pale yellow crystalline
solid (4.2 g, yield 82.4%). Mp: 106-108 °C. 1H NMR (500 MHz,
CDCl3, ppm): δ ) 1.3 (s, 18 H, -CH3), 4.7 (s, 2 H, -CH2OH),
5.2 (s, 4 H, -CH2-), 6.5 (s, 1 H, Ph-H), 6.7 (s, 2 H, Ph-H),
7.5 (d, 4 H, J ) 8.1 Hz), 7.55 (d, 4 H, J ) 7.8 Hz), 8.05 (d, 4 H,
J ) 8.0 Hz), 8.15 (d, 4 H, J ) 7.8 Hz).
(OXZ)2-(G-1)-OSO2Me (7) (Met h a n esu lfon ic Acid 3,5-
Bis{4-[5-(4-ter t-b u t ylp h en yl)-[1,3,4]oxa d ia zol-2-yl]b en -
zyloxy}ben zyl Ester ). A solution of compound 6 (6.1 g, 1.25
mmol) in anhydrous CH2Cl2 (20 mL) was stirred at room
temperature. MeSO2Cl (0.142 g, 1.25 mmol) and triethylamine
(0.126 g, 1.25 mmol) were added dropwise to the solution and
stirred for 24 h. Then water was added to the solution. The
aqueous layer was extracted with CH2Cl2 (40 mL × 3). The
extract was dried with anhydrous MgSO4 and evaporated to
give compound 7 (4.2 g, yield 95.5%). Mp: 104-105 °C. 1H
NMR (500 MHz, CDCl3, ppm): δ ) 1.3 (s, 18 H, -CH3), 1.6 (s,
3 H, -CH3), 4.5 (s, 2 H, -CH2O-), 5.2 (s, 4 H, -CH2-), 6.5 (s,
1 H, Ph-H), 6.7 (s, 2 H, Ph-H), 7.5 (d, 4 H, J ) 8.4 Hz), 7.55
(d, 4 H, J ) 7.6 Hz), 8.05 (d, 4 H, J ) 8.0 Hz), 8.15 (d, 4 H, J
) 8.3 Hz).
(CZ)2-(G-1)-Br . A mixture of compound 4 (1.0 g, 1.72 mmol)
and CBr4 (0.44 g, 1.25 mmol) in dry CH2Cl2 (20 mL) was cooled
to 0 °C. Triphenylphosphine (0.4 g, 1.5 mmol) was then slowly
added and stirred for 5 h. After CH2Cl2 was removed, the
product was purified by column chromatography on silica gel
using CH2Cl2 as eluent to give a pale yellow powder (1.02 g,
yield 92.1%). Mp: 163-164 °C. 1H NMR (500 MHz, CDCl3,
ppm): δ ) 1.8 (m, 4 H, -CH2), 2.1 (m, 4 H, -CH2), 3.85 (t, 4
H, J ) 6.1 Hz, -NCH2-), 4.2 (s, 2 H, -CH2Br), 4.37 (t, J )
7.1 Hz, 4 H, -OCH2-), 6.30 (s, 1 H, Ph-H), 6.45 (s, 2 H, Ph-
luminescence properties, whose efficiency is dependent
on the dendrimer generation number. Time-resolved
luminescence further supported the conclusion that the
contribution tendency for each peripheral donor is
decreased with increasing the generation number, es-
pecially for the third-generation dendrimers. Specifi-
cally, the intensity of an enhanced emission for the
dendrimers synthesized in this study is stronger than
that of a direct-core emission; that is, the light harvest
for the luminescence of the chromophore by the light
antenna is more efficient than direct excitation at the
absorption maximum by an external light source. All
dendrimers including three generations can be spin-
coated from solution to form good quality thin films and
have good thermal stability. The preliminary EL results
with a single-layer architecture made with the den-
drimers demonstrate that these dendrimers could be
utilized as a promising active nondoping emitter with
charge carrier-transporting ability.
Exp er im en ta l Section
Instrumentation. Melting points were measured on an X4
micromelting point apparatus. 1H NMR and 13C NMR spectra
were recorded on a Bruker AM-500 spectrometer. MS were
recorded on FAB or MALDI-TOF mass spectroscopy using
R-cyano-4-hydroxycinnamic acid as a matrix. Glass-transition
temperatures (Tg) were measured using a differential scanning
calorimeter TA DSC 2910 instrument at a scan rate of 10 °C/
min. Absorption and fluorescence spectra were recorded on a
Varian Cary 500 and a Varian Cary Eclipse, respectively. The
nanoparticle TiO2 used in this study is produced by Alfa Aesar
Co. and is the anatase 99.9% (metals basis), which is for
research and development use only, with reagent number 27
AF-39953.
Cyclic voltammetry (CV) measurements were carried out
on a CHI 800 electrochemical instrument with a platinum
electrode using millimolar solutions in CH2Cl2 containing 0.1
M of the support electrolyte of tetrabutylammonium perchlo-
ride, in a three-electrode cell and potentiostat assembly. The
potentials were measured at the scan rate of 100 mV/s. Ag/
AgCl electrode is the reference electrode, and each measure-
ment was calibrated with an internal standard of the ferrocene/
ferrocenium (Fc) system.
The dendrimer films were spin-coated on ITO glass from
the chlorobenzene solution. OLEDs are prepared according to
the following standard procedure: ITO coated glass substrates
were cleaned via repeated ultrasonic washing and oxygen
plasma treating. The buffer layer was spin-coated from the
aqueous dispersion of poly(3,4-ehtylenedioxythiophene-poly-
styrenesulfonic acid) (PEDOT) (Bayer AG). The active den-
drimer layer was spin-coated from 2 wt % chlorobenzene
solution. The cathode layer of Ba (4 nm)/Al (150 nm) was
thermally evaporated in a vacuum chamber (pressure < 2 ×
10-4 Pa). The thickness of different layers was measured by
Tencor R-step 500 surface-profiler. The I-V and L-V charac-
teristics were measured with a computer-controlled source
meter Keithley 236 and Si-photodiode calibrated by an inte-
grating sphere. The EL spectra were recorded on an Oriel CCD
spectrograph.
The fluorescence lifetime study was performed by an Ed-
inburgh FL 900 single-photon counting system with a hydrogen-
filled flash lamp/or a nitrogen lamp as the excitation source.
Data were analyzed using a nonlinear least-squares fitting
program, with deconvolution of the exciting pulse being ∼200
ps.
Syn th esis. (CZ)2-(G-1)-OH (4) ([3,5-Bis(4-ca r ba zol-9-yl-
bu tyloxy)p h en yl]m eth a n ol). A mixture of 9-(4-bromo-butyl)-
9H-carbazole (4.4 g, 14.5 mmol), 3,5-dihydroxybenzyl alcohol
(1.0 g, 7.1 mmol), potassium carbonate (3.4 g, 60 mmol), and
18-crown-6 (0.38 g, 1.42 mmol) in anhydrous acetone (50 mL)
was heated at reflux and stirred vigorously under nitrogen for
56 h. The mixture was allowed to cool and evaporated to

4396 Du et al.
Macromolecules, Vol. 37, No. 12, 2004
H), 7.2 (t, 4 H, Ph-H(CZ), J ) 7.3 Hz), 7.4 (d, 4 H, Ph-H(CZ),
J ) 8.0 Hz), 7.48 (t × d, 4 H, Ph-H(CZ), J ) 7.8 Hz, J ) 1.0
Hz), 8.2 (d, 4 H, Ph-H(CZ), J ) 7.8 Hz).
stirred vigorously for 24 h. After cooling to ambient temper-
ature, the mixture was poured into water, filtered, and then
purified by column chromatography on silica gel, eluting with
CH2Cl2 to give 2OXZ-NP3 (0.141 g, yield 51%). Mp: 154-155
°C. 1H NMR (500 MHz, CDCl3, ppm): δ ) 1.3 (s, 18 H, -CH3),
3.3 (t, 4 H, N-CH2, J ) 4.4 Hz), 4.05 (t, 4 H, O-CH2, J ) 4.4
Hz), 5.2 (s, 4 H, PhO-CH2-Ph), 5.4 (s, 2 H, PhCOO-CH2-
Ph), 6.6 (s, 1 H, Ph-H), 6.75 (s, 2 H, Ph-H), 7.2 (d, 1 H,
naphthalene-H, J ) 8.1 Hz), 7.4 (d, 2 H, Ph-H), 7.6 (d, 4 H,
Ph-H(OXZ)), 7.65 (d, 4 H, Ph-H(OXZ)), 7.72 (t, 1 H, naph-
thalene-H), 8.1 (d, 4 H, Ph-H(OXZ), J ) 7.9 Hz), 8.2 (d, 4 H,
Ph-H(OXZ), J ) 7.8 Hz), 8.25 (s, 2 H, Ph-H), 8.4 (d, 1 H,
naphthalene-H, J ) 8.5 Hz), 8.5 (d, 1 H, naphthalene-H, J )
8.1 Hz), 8.6 (d, 1 H, naphthalene-H, J ) 7.2 Hz).
(CZ)4-(G-2)-OH (1). A mixture of (CZ)2-(G-1)-Br (8.3 g, 14.5
mmol), 3,5-dihydroxybenzyl alcohol (1.0 g, 7.1 mmol), potas-
sium carbonate (3.4 g, 60 mmol), and 18-crown-6 (0.38 g, 1.42
mmol) in 50 mL of anhydrous THF was heated at reflux and
stirred vigorously under nitrogen for 56 h. The mixture was
allowed to cool and evaporated to dryness under reduced
pressure. The residue was partitioned between CH2Cl2 and
water, and the aqueous layer was extracted with CH2Cl2 (40
mL × 3). The combined extracts were dried with anhydrous
MgSO4 and evaporated. The product was purified by column
chromatography on silica gel eluting with CH2Cl2 to give 1 as
pale yellow powder (7.1 g, yield 79.2%). Mp: 96-98 °C. 1H
NMR (500 MHz, CDCl3, ppm): δ ) 1.8 (m, 8 H, -CH2), 2.05
(m, 8 H, -CH2), 3.85 (t, J ) 6.1 Hz, 8 H, -NCH2-), 4.37 (t, J
) 7.0 Hz, 8 H, -OCH2-), 4.6 (s, -CH2OH, 2 H,), 4.9 (4 H,
-OCH2-), 6.25 (s, 2 H, Ph-H), 6.4 (s, 5 H, Ph-H), 6.5 (s, 2
H, Ph-H), 7.2 (t × d, J ) 7.8 Hz, J ) 1.0 Hz, 8 H, Ph-H(CZ)),
7.4 (d, J ) 7.9 Hz, 8 H, Ph-H(CZ)), 7.48 (t × d, J ) 7.9 Hz, J
) 1.0 Hz, 8 H, Ph-H(CZ)), 8.2 (d, J ) 7.7 Hz, 8 H, Ph-H(CZ)).
(CZ)4-(G-2)-OSO2Me (2). A solution of (CZ)4-(G-2)-OH (1.8
g, 1.43 mmol) in anhydrous CH2Cl2 (20 mL) was stirred at
room temperature. MeSO2Cl (0.162 g, 1.43 mmol) and triethyl-
amine (0.144 g, 1.43 mmol) were added dropwise to the
solution and stirred for 24 h. Then water was added to the
solution. The aqueous layer was extracted with CH2Cl2 (40 mL
× 3). The extract was dried with anhydrous MgSO4 and
evaporated. The product was purified by column chromatog-
raphy on silica gel eluting with CH2Cl2 to give white powder
(1.8 g, yield 94.6%). Mp: 70-71 °C. 1H NMR (500 MHz, CDCl3,
ppm): δ ) 1.6 (s, 3 H, -CH3), 1.8 (m, 8 H, -CH2), 2.05 (m, 8
H, -CH2), 3.85 (t, J ) 6.1 Hz, 8 H, -NCH2-), 4.37 (t, J ) 7.0
Hz, 8 H, -OCH2-), 4.5 (s, -CH2OMS, 2 H), 4.9 (s, 4 H,
-OCH2-), 6.25 (s, 2 H, Ph-H), 6.4 (s, 5 H, Ph-H), 6.5 (s, 2
H, Ph-H), 7.2 (t, 8 H, Ph-H(CZ)), 7.4 (d, 8 H, Ph-H(CZ)),
7.48 (t, 8 H, Ph-H(CZ)), 8.1 (d, J ) 7.6 Hz, 8 H, Ph-H(CZ)).
2OXZ-NP 1. A mixture of compound 7 (0.45 g, 0.56 mmol),
compound 11 (0.10 g, 0.28 mmol), and potassium carbonate
(0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C
and stirred vigorously for 24 h. After cooling to ambient
temperature, the mixture was poured into water, filtered, and
then purified by column chromatography on silica gel, eluting
with CH2Cl2 to give 2OXZ-NP1 (0.16 g, yield 54%). Mp: 149-
4OXZ-NP 1. A mixture of compound 7 (0.41 g, 0.52 mmol),
compound 9 (0.1 g, 0.25 mmol), and potassium carbonate (0.1
g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C and
stirred vigorously for 24 h. After cooling to ambient temper-
ature, the mixture was poured into water, filtered, and then
purified by column chromatography on silica gel, eluting with
CH2Cl2 to give 4OXZ-NP1 (0.073 g, yield 16.3%). Mp: 196-
198 °C. 1H NMR (500 MHz, CDCl3, ppm): δ ) 1.3 (s, 36 H,
-CH3), 3.1 (s, 6 H, -N(CH3)2), 5.1 (s, 8 H, PhO-CH2-Ph),
5.4 (s, 4 H, PhCOO-CH2-Ph), 6.5 (s, 2 H, Ph-H), 6.7 (s, 4 H,
Ph-H), 7.15 (d, J ) 8.3 Hz, 1 H, naphthalene-H), 7.5 (d, J )
8.3 Hz, 8 H, Ph-H(OXZ)), 7.6 (d, J ) 8.0 Hz, 8 H, Ph-H
(OXZ)), 7.7 (t, J ) 7.9 Hz, 1 H, naphthalene-H), 8.05 (d, J )
8.2 Hz, 8 H, Ph-H(OXZ)), 8.13 (d, J ) 8.1 Hz, 8 H, Ph-
H(OXZ)), 8.25 (s, 2 H, Ph-H), 8.44 (d, J ) 8.2 Hz, 1 H,
naphthalene-H), 8.48 (d, J ) 8.2 Hz, 1 H, naphthalene-H), 8.6
(d, J ) 7.1 Hz, 1 H, naphthalene-H), 8.9 (s, 1 H, Ph-H). 13C
NMR (100 MHz, CDCl3): δ ) 31.121, 35.096, 44.739, 66.941,
69.443, 82.711, 107.354, 112.367, 121.049, 123.552, 126.047,
126.779, 127.122, 127.778, 138.223, 140.550, 155.351, 159.830,
164.118, 164.675, 171.648. MS (FAB): m/z [M+] 1811, [M+
Na] 1833.
+
4OXZ-NP 2. A mixture of compound 7 (0.38 g, 0.473 mmol),
compound 10 (0.10 g, 0.23 mmol), and potassium carbonate
(0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C
and stirred vigorously for 24 h. After cooling to ambient
temperature, the mixture was poured into water, filtered, and
then purified by column chromatography on silica gel, eluting
with CH2Cl2 to give 4OXZ-NP2 (0.103 g, yield 24.8%). Mp:
172-173 °C.1H NMR (500 MHz, CDCl3): δ ) 1.4 (s, 36 H,
-CH3), 1.65 (m, 2 H, -CH2-), 1.85 (m, 4 H, -CH2-), 3.2 (t, 4
H, -NCH2), 5.1 (s, 8 H, PhO-CH2-Ph), 5.4 (s, 4 H, PhCOO-
CH2-Ph), 6.5 (s, 2 H, Ph-H), 6.7 (s, 4 H, Ph-H), 7.25 (d, J )
8.2 Hz, 1 H, naphthalene-H), 7.55 (d, J ) 8.0 Hz, 8 H, Ph-
H(OXZ)), 7.6 (d, J ) 7.8 Hz, 8 H, Ph-H(OXZ)), 7.7 (t, J ) 7.9
Hz, 1 H, naphthalene-H), 8.05 (d, J ) 8.0 Hz, 8 H, Ph-
H(OXZ)), 8.13 (d, J ) 7.8 Hz, 8 H, Ph-H(OXZ)), 8.25 (s, 2 H,
Ph-H), 8.44 (d, J ) 8.5 Hz, 1 H, naphthalene-H), 8.48 (d, J )
8.0 Hz, 1 H, naphthalene-H), 8.6 (d, J ) 7.2 Hz, 1 H,
naphthalene-H), 8.9 (s, 1 H, Ph-H). 13C NMR (100 MHz,
CDCl3): δ ) 23.392, 31.121, 35.088, 69.436, 107.354, 121.065,
126.047, 126.779, 127.130, 127.786, 137.613, 140.543, 155.344,
159.838, 164.705, 168.314, 198.664, 212.733, 230.181. MS
(FAB): m/z [M+] 1852.
1
150 °C. H NMR (500 MHz, CDCl3, ppm): δ ) 1.35 (s, 18 H,
-CH3), 3.15 (s, 6 H, N(CH3)2), 5.15 (s, 4 H, PhO-CH2-Ph),
5.38 (s, 2 H, PhCOO-CH2-Ph), 6.6 (s, 1 H, Ph-H), 6.75 (s, 2
H, Ph-H), 7.15 (d, 1 H, naphthalene-H, J ) 8.3 Hz), 7.4 (d, 2
H, Ph-H, J ) 7.2 Hz), 7.55 (d, 4 H, Ph-H(OXZ), J ) 8.1 Hz),
7.6 (d, 4 H, Ph-H(OXZ), J ) 8.2 Hz), 7.7 (t, 1 H, naphthalene-
H), 8.05 (d, 4 H, Ph-H(OXZ), J ) 8.5 Hz), 8.18 (d, 4 H, Ph-
H(OXZ), J ) 8.1 Hz), 8.25 (d, 2 H, Ph-H), 8.49 (d, 1 H,
naphthalene-H), 8.51 (d, 1 H, naphthalene-H), 8.6 (d, 1 H,
naphthalene-H, J ) 7.2 Hz).
2OXZ-NP 2. A mixture of compound 7 (0.40 g, 0.5 mmol),
compound 12 (0.10 g, 0.25 mmol), and potassium carbonate
(0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C
and stirred vigorously for 24 h. After cooling to ambient
temperature, the mixture was then filtered and purified by
column chromatography on silica gel. eluting with CH2Cl2 to
give 2OXZ-NP2 (0.103 g, yield 51%). Mp: 154-155 °C. 1H
NMR (500 MHz, CDCl3, ppm): δ ) 1.3 (s, 18 H, -CH3), 1.75
(m, 2 H, -CH2-), 1.9 (m, 4 H, -CH2-), 3.5 (t, 4 H, N-CH2),
5.2 (s, 4 H, PhO-CH2-Ph), 5.4 (s, 2 H, PhCOO-CH2-Ph),
6.6 (s, 1 H, Ph-H), 6.75 (s, 2 H, Ph-H), 7.2 (d, 1 H,
naphthalene-H, J ) 8.1 Hz), 7.4 (d, 2 H, Ph-H), 7.6 (d, 4 H,
Ph-H(OXZ)), 7.65 (d, 4 H, Ph-H(OXZ)), 7.72 (t, 1 H, naph-
thalene-H), 8.1 (d, 4 H, Ph-H(OXZ), J ) 7.9 Hz), 8.2 (d, 4 H,
Ph-H(OXZ), J ) 7.8 Hz), 8.25 (d, 2 H, Ph-H, J ) 8.4 Hz), 8.4
(d, 1 H, naphthalene-H, J ) 8.5 Hz), 8.5 (d, 1 H, naphthalene-
H, J ) 8.1 Hz), 8.6 (d, 1 H, naphthalene-H, J ) 7.2 Hz).
2OXZ-NP 3. A mixture of compound 7 (0.4 g, 0.5 mmol),
compound 13 (0.1 g, 0.25 mmol), and potassium carbonate (0.1
g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C and
4OXZ-NP 3. A mixture of compound 7 (0.38 g, 0.473 mmol),
compound 3 (0.10 g, 0.22 mmol), and potassium carbonate
(0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C
and stirred vigorously for 24 h. After cooling to ambient
temperature, the mixture was poured into water, filtered, and
then purified by column chromatography on silica gel eluting
with CH2Cl2 to give 4OXZ-NP3 (0.086 g, yield 20.7%). Mp:
195-196 °C. 1H NMR (500 MHz, CDCl3): δ ) 1.4 (s, 36 H,
-CH3), 3.3 (t, 4 H, -NCH2-), 4.0 (t, 4 H, -OCH2-), 5.1 (s, 8
H, PhO-CH2-Ph), 5.4 (s, 4 H, PhCOO-CH2-Ph), 6.5 (s, 2 H,
Ph-H), 6.7 (s, 4 H, Ph-H), 7.25 (d, J ) 8.1 Hz, 1 H,
naphthalene -H), 7.55 (d, J ) 8.0 Hz, 8 H, Ph-H(OXZ)), 7.6
(d, J ) 7.8 Hz, 8 H, Ph-H(OXZ)), 7.7 (t, J ) 7.6 Hz, 1 H,
naphthalene-H), 8.05 (d, J ) 7.9 Hz, 8 H, Ph-H(OXZ)), 8.13
(d, J ) 7.7 Hz, 8 H, Ph-H(OXZ)), 8.25 (s, 2 H, Ph-H), 8.44
(d, J ) 8.3 Hz, 1 H, naphthalene-H), 8.48 (d, J ) 7.8 Hz, 1 H),

Macromolecules, Vol. 37, No. 12, 2004
Novel Naphthalimide Dendrimers 4397
naphthalene-H), 8.6 (d, J ) 6.9 Hz, 1 H, naphthalene-H), 8.9
(s, 1 H, Ph-H).
naphthalene-H), 8.5 (d, J ) 7.1 Hz, 1 H, naphthalene-H), 8.82
(s, 1 H, Ph-H).
4CZ-NP 2. A mixture of compound 5 (0.30 g, 0.473 mmol),
compound 10 (0.10 g, 0.23 mmol), and potassium carbonate-
(0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C
and stirred vigorously for 24 h. After cooling to ambient
temperature, the mixture was poured into water, filtered, and
then purified by column chromatography on silica gel, eluting
with CH2Cl2 to give 4CZ-NP2 (0.072 g, yield 20.2%). Mp: 139-
140 °C. 1H NMR (500 MHz, CDCl3): δ ) 1.65 (m, 2 H, -CH2-
), 1.75 (m, 8 H, -CH2), 1.8 (m, 4 H, -CH2), 2.1 (m, 8 H, -CH2),
3.2 (t, 4 H, -NCH2), 3.85 (t, J ) 6.1 Hz, 8 H, -NCH2-), 4.37
(t, J ) 7.1 Hz, 8 H, -CH2-O), 5.2 (s, 4 H, -CH2O-), 6.3 (s, 2
H, Ph-H), 6.5 (s, 4 H, Ph-H), 7.07 (d, J ) 8.2 Hz, 1 H,
naphthalene-H), 7.17 (t, J ) 7.3 Hz, 8 H, Ph-H(CZ)), 7.38 (d,
J ) 8.0 Hz, 8 H, Ph-H(CZ)), 7.42 (t, J ) 7.6 Hz, 8 H, Ph-
H(CZ)), 7.6 (t, J ) 7.9 Hz, 1 H, naphthalene-H), 8.1 (d, J )
7.6 Hz, 8 H, Ph-H(CZ)), 8.2 (s, 2 H, Ph-H), 8.37 (d, J ) 8.0
Hz, 1 H, naphthalene-H), 8.42 (d, J ) 8.2 Hz, 1 H, naphthalene-
H), 8.5 (d, J ) 7.1 Hz, 1 H, naphthalene-H), 8.82 (s, 1 H, Ph-
H).13C NMR (100 MHz, CDCl3): δ ) 15.831, 25.788, 26.169,
26.866, 39.208, 42.656, 54.467, 67.132, 67.521, 69.741, 98.313,
101.365, 106.790, 108.621, 114.656, 115.144, 118.768, 120.294,
122.713, 122.796 125.612, 130.319, 131.326, 131.502, 131.845,
133.218, 134.752, 136.415, 137.712, 140.314, 160.150, 164.743.
MS (FAB): m/z [M+] 1574.
2CZ-NP 1. A mixture of compound 5 (0.33 g, 0.52 mmol),
compound 11 (0.1 g, 0.28 mmol), and potassium carbonate (0.1
g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C and
stirred vigorously for 24 h. After cooling to ambient temper-
ature, the mixture was poured into water, filtered, and then
purified by column chromatography on silica gel, eluting with
CH2Cl2 to give 2CZ-NP1 (0.21 g, yield 55.3%). Mp: 136-137
°C.1H NMR (500 MHz, CDCl3): δ ) 1.8 (m, 4 H, -CH2-), 2.1
(m, 4 H, -CH2), 3.05 (s, 6 H, -N(CH3)2), 3.85 (t, J ) 6.1 Hz,
4 H, -NCH2-), 4.37 (t, J ) 6.5 Hz, 4 H, -CH2O-), 5.25 (s, 2
H, -CH2O-), 6.3 (s, 1 H, Ph-H), 6.5 (s, 2 H, Ph-H), 7.2 (d, J
) 8.3 Hz, 1 H, naphthalene-H), 7.25 (t, J ) 7.1 Hz, 4 H, Ph-
H(CZ)), 7.38 (d, J ) 7.9 Hz, 4 H, Ph-H (CZ)), 7.42 (t, J ) 7.4
Hz, 4 H, Ph-H(CZ)), 7.5 (d, J ) 7.1 Hz, 2 H, Ph-H), 7.75 (t,
J ) 7.8 Hz, 1 H, naphthalene-H), 8.05 (d, J ) 7.9 Hz, 4 H,
Ph-H(CZ)), 8.25 (d, J ) 8.4 Hz, 2 H, Ph-H), 8.5 (d, J ) 8.5
Hz, 1 H, naphthalene-H), 8.6 (d, J ) 8.0 Hz, 1 H, naphthalene-
H), 8.75 (d, J ) 7.2 Hz, 1 H, naphthalene-H).
2CZ-NP 2. A mixture of compound 5 (0.304 g, 0.473 mmol),
compound 12 (0.1 g, 0.25 mmol), and potassium carbonate-
(0.1 g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C
and stirred vigorously for 24 h. After cooling to ambient
temperature, the mixture was poured into water, filtered, and
then purified by column chromatography on silica gel, eluting
with CH2Cl2 to give 2CZ-NP2 (0.18 g, yield 50%). Mp: 136-
138 °C. 1H NMR (500 MHz, CDCl3): δ ) 1.65 (m, 2 H, -CH2-
), 1.75 (m, 4 H, -CH2), 1.8 (m, 4 H, -CH2), 2.1 (m, 4 H, -CH2),
3.2 (t, 4 H, -NCH2), 3.85 (t, J ) 6.1 Hz, 4 H, -NCH2-), 4.37
(t, J ) 7.1 Hz, 4 H, -CH2-O), 5.2 (s, 2 H, -CH2O-), 6.3 (s, 1
H, Ph-H), 6.5 (s, 2 H, Ph-H), 7.2 (d, J ) 8.2 Hz, 1 H,
naphthalene-H), 7.2 (t, J ) 7.3 Hz, 4 H, Ph-H(CZ)), 7.4 (d, J
) 8.0 Hz, 4 H, Ph-H(CZ)), 7.45 (t, J ) 7.6 Hz, 4 H, Ph-H(CZ)),
7.5 (d, J ) 8.0 Hz, 2 H, Ph-H), 7.75 (t, J ) 7.9 Hz, 1 H,
naphthalene-H), 8.1 (d, J ) 7.9 Hz, 4 H, Ph-H(CZ)), 8.25 (d,
J ) 8.4 Hz, 2 H, Ph-H), 8.5 (d, J ) 7.8 Hz, 1 H, naphthalene-
H), 8.6(d, J ) 8.0 Hz, 1 H, naphthalene-H), 8.75 (d, J ) 7.2
Hz, 1 H, naphthalene-H).
4CZ-NP 3. A mixture of compound 5 (0.31 g, 0.473 mmol),
compound 3 (0.10 g, 0.22 mmol), and potassium carbonate
(0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C
and stirred vigorously for 24 h. After cooling to ambient
temperature, the mixture was poured into water, filtered, and
then purified by column chromatography on silica gel, eluting
with CH2Cl2 to give 4CZ-NP3 (0.079 g, yield 22.3%). Mp: 194-
1
195 °C. H NMR (500 MHz, CDCl3): δ ) 1.7 (m, 8 H, -CH2),
1.95 (m, 8 H, -CH2), 3.2 (t, J ) 4.0 Hz, 4 H, -NCH2), 3.8 (t,
J ) 6.0 Hz, 8 H, N-CH2), 3.94 (t, J ) 4.2 Hz, 4 H, -CH2-O),
4.25 (t, J ) 2.1 Hz, 8 H, -CH2O-), 6.3 (s, 2 H, Ph-H), 6.4 (s,
4 H, Ph-H), 7.05 (d, J ) 8.1 Hz, 1 H, naphthalene-H), 7.2 (t,
J ) 7.3 Hz, 8 H, Ph-H(CZ)), 7.3 (d, J ) 8.0 Hz, 8 H, Ph-
H(CZ)), 7.38 (t, J ) 7.5 Hz, 8 H, Ph-H(CZ)), 7.55 (t, J ) 7.9
Hz, 1 H, naphthalene-H), 7.98 (d, J ) 7.7 Hz, 8 H, Ph-H(CZ)),
8.12 (s, 2 H, Ph-H), 8.33 (d, J ) 8.0 Hz, 1 H, naphthalene-H),
8.37 (d, J ) 8.2 Hz, 1 H, naphthalene-H), 8.45 (d, J ) 7.1 Hz,
1 H, naphthalene-H), 8.82 (s, 1 H, Ph-H).13C NMR (100 MHz,
CDCl3): δ ) 25.795, 26.894, 42.672, 53.368, 66.911, 67.544,
106.813, 108.621, 109.758, 118.783, 120.309, 122.812, 125.619,
131.906, 137.712, 140.321, 160.166, 164.713. MS (FAB): m/z
[M+] 1576.
2CZ-NP 3. A mixture of compound 5 (0.31 g, 0.473 mmol),
compound 13 (0.1 g, 0.25 mmol), and potassium carbonate (0.1
g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C and
stirred vigorously for 24 h. After cooling to ambient temper-
ature, the mixture was poured into water, filtered, and then
purified by column chromatography on silica gel, eluting with
CH2Cl2 to give 2CZ-NP3 (0.21, yield 58.3%). Mp: 150-151 °C.
1H NMR (500 MHz, CDCl3): δ ) 1.8 (m, 4 H, -CH2-), 2.1 (m,
4 H, -CH2), 3.27 (t, 4 H, -NCH2), 3.9 (t, J ) 6.1 Hz, 4 H,
N-CH2), 4.05 (t, J ) 4.3 Hz, 4 H, -CH2-O), 4.4 (t, J ) 7.0
Hz, 4 H, -CH2O-), 5.2 (s, 2 H, -CH2O-), 6.3 (s, 1 H, Ph-H),
6.5 (s, 2 H, Ph-H), 7.19 (t, J ) 7.1 Hz, 4 H, Ph-H(CZ)), 7.25
(d, J ) 8.3 Hz, 1 H, naphthalene-H), 7.38 (d, J ) 7.9 Hz, 4 H,
Ph-H (CZ)), 7.42 (t, J ) 7.4 Hz, 4 H, Ph-H(CZ)), 7.5 (d, J )
7.1 Hz, 2 H, Ph-H), 7.75 (t, J ) 7.8 Hz, 1 H, naphthalene-H),
8.05 (d, J ) 7.9 Hz, 4 H, Ph-H(CZ)), 8.25 (d, J ) 8.4 Hz, 2 H,
Ph-H), 8.5 (d, J ) 8.5 Hz, 1 H, naphthalene-H), 8.6 (d, J )
8.0 Hz, 1 H, naphthalene-H), 8.75 (d, J ) 7.2 Hz, 1 H,
naphthalene-H).
8CZ-NP 1. A mixture of (CZ)4-(G-2)-OMS (0.34 g, 0.25
mmol), compound 9 (0.05 g, 0.12 mmol), and potassium
carbonate (0.1 g, 0.72 mmol) in dry DMF (10 mL) was heated
to 100 °C and stirred vigorously for 24 h. After cooling to
ambient temperature, the mixture was poured into water,
filtered, and then purified by column chromatography on silica
gel, eluting with CH2Cl2 to give 8CZ-NP1 (0.095 g, yield
26.1%). Mp: 107-109 °C.1H NMR (500 MHz, CDCl3): δ ) 1.8
(m, 16 H, -CH2-), 2.1 (m, 16 H, -CH2), 3.05 (s, 6 H,
-N(CH3)2), 3.85 (t, 16 H, -NCH2-), 4.3 (t, 16 H, -CH2O-),
4.83 (s, 8 H, -CH2O-), 5.25 (s, 4 H, -CH2O-), 6.25 (s, 4 H,
Ph-H), 6.45 (s, 8 H, Ph-H), 6.5 (s, 2 H, Ph-H), 6.7(s, 4 H,
Ph-H), 7.15 (d, J ) 7.3 Hz, 1 H, naphthalene-H), 7.2 (t, J )
7.4 Hz, 16 H, Ph-H(CZ)), 7.38 (d, J ) 8.0 Hz, 16 H, Ph-H
(CZ)), 7.42 (t, J ) 8.3 Hz, 16 H, Ph-H(CZ)), 7.6(t, J ) 7.8 Hz,
1 H, naphthalene-H), 8.1 (d, J ) 7.7 Hz, 16 H, Ph-H(CZ)),
8.2 (s, 2 H, Ph-H), 8.37 (d, J ) 8.5 Hz, 1 H, naphthalene-H),
8.42 (d, J ) 8.2 Hz, 1 H, naphthalene-H), 8.5 (d, 1 H,
naphthalene-H), 8.92 (s, 1 H, Ph-H). MS (MALDI-TOF): m/z
[M+ + Na] 2930.42, [M+ + K] 2946.39.
4CZ-NP 1. A mixture of compound 5 (0.33 g, 0.52 mmol),
compound 9 (0.1 g, 0.25 mmol), and potassium carbonate (0.1
g, 0.72 mmol) in dry DMF (10 mL) was heated to 100 °C and
stirred vigorously for 24 h. After cooling to ambient temper-
ature, the mixture was poured into water, filtered, and then
purified by column chromatography on silica gel, eluting with
CH2Cl2 to give 4CZ-NP1 (0.063 g, yield 16.6%. Mp: 144-145
°C. 1H NMR (500 MHz, CDCl3): δ ) 1.8 (m, 8 H, -CH2-), 2.1
(m, 8 H, -CH2), 3.05 (s, 6 H, -N(CH3)2), 3.85 (t, J ) 6.1 Hz,
8 H, -NCH2-), 4.37 (t, J ) 6.5 Hz, 8 H, -CH2O-), 5.25 (s, 4
H, -CH2O-), 6.3 (s, 2 H, Ph-H), 6.5 (s, 4 H, Ph-H), 7.05 (d,
J ) 8.3 Hz, 1 H, naphthalene-H), 7.2 (t, J ) 7.1 Hz, 8 H, Ph-
H(CZ)), 7.38 (d, J ) 7.9 Hz, 8 H, Ph-H (CZ)), 7.42 (t, J ) 7.4
Hz, 8 H, Ph-H(CZ)), 7.6 (t, J ) 7.9 Hz, 1 H, naphthalene-H),
8.05 (d, J ) 7.6 Hz, 8 H, Ph-H(CZ)), 8.2 (s, 2 H, Ph-H), 8.37
(d, J ) 8.3 Hz, 1 H, naphthalene-H), 8.42 (d, J ) 8.4 Hz, 1 H,
8CZ-NP 2. A mixture of (CZ)4-(G-2)-OMS (0.31 g, 0.23
mmol), compound 10 (0.05 g, 0.11 mmol), and potassium
carbonate (0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated
to 100 °C and stirred vigorously for 24 h. After cooling to
ambient temperature, the mixture was poured into water,
filtered, and then purified by column chromatography on silica
gel, eluting with CH2Cl2 to give 8CZ-NP2 (0.1 g, yield 30%).

4398 Du et al.
Macromolecules, Vol. 37, No. 12, 2004
Mp: 115-117 °C.1H NMR (500 MHz, CDCl3): δ ) 1.65 (m, 2
H, -CH2-), 1.75 (m, 16 H, -CH2-), 1.8 (m, 4 H, -CH2), 2.0
(m, 16 H, -CH2), 3.2 (t, 4 H, -NCH2), 3.85 (t, 16 H, -NCH2-
), 4.37 (t, 16 H, -CH2O-), 4.8 (s, 8 H, -CH2O-), 5.25 (s, 4 H,
-CH2O-), 6.3 (s, 4 H, Ph-H), 6.45 (s, 8 H, Ph-H), 6.5 (s, 2
H, Ph-H), 6.65 (s, 4 H, Ph-H), 7.05 (d, J ) 8.3 Hz, 1 H,
naphthalene-H), 7.23 (t, J ) 7.2 Hz, 16 H, Ph-H(CZ)), 7.38
(d, J ) 7.9 Hz, 16 H, Ph-H (CZ)), 7.42 (t, J ) 7.4 Hz, 16 H,
Ph-H(CZ)), 7.62 (t, 1 H, naphthalene-H), 8.05 (d, J ) 7.6 Hz,
16 H, Ph-H(CZ)), 8.18 (s, 2 H, Ph-H), 8.37 (d, 1 H, naphtha-
lene-H), 8.42 (d, J ) 7.9 Hz, 1 H, naphthalene-H), 8.48 (d, J
) 7.1 Hz, 1 H, naphthalene-H), 8.9 (s, 1 H, Ph-H). MS
(MALDI-TOF): m/z [M+ + Na] 2970.40, [M+ + K] 2986.33.
8CZ-NP 3. A mixture of (CZ)4-(G-2)-OMS (0.31 g, 0.23
mmol), compound 3 (0.05 g, 0.11 mmol), and potassium
carbonate (0.10 g, 0.72 mmol) in dry DMF (10 mL) was heated
to 100 °C and stirred vigorously for 24 h. After cooling to
ambient temperature, the mixture was poured into water,
filtered, and then purified by column chromatography on silica
gel eluting with CH2Cl2 to give 8CZ-NP3 (0.11 g, yield 33%.)
Mp: 116-118 °C.1H NMR (500 MHz, CDCl3): δ ) 1.75 (m, 16
H, -CH2-), 2.0 (m, 16 H, -CH2), 3.1 (t, 4 H, -NCH2), 3.85 (t,
J ) 6.1 Hz, 16 H, -NCH2-), 3.9 (t, 4 H, -OCH2), 4.3 (t, J )
6.5 Hz, 16 H, -CH2O-), 4.8 (s, 8 H, -CH2O-), 5.25 (s, 4 H,
-CH2O-), 6.25 (s, 4 H, Ph-H), 6.45 (s, 8 H, Ph-H), 6.5 (s, 2
H, Ph-H), 6.65 (s, 4 H, Ph-H), 6.95 (d, J ) 8.1 Hz, 1 H,
naphthalene-H), 7.2 (t, J ) 6.8 Hz, 16 H, Ph-H(CZ)), 7.38 (d,
J ) 7.8 Hz, 16 H, Ph-H (CZ)), 7.42 (t, J ) 7.9 Hz, 16 H, Ph-
H(CZ)), 7.6(t, J ) 7.9 Hz, 1 H, naphthalene-H), 8.05 (d, J )
7.6 Hz, 16 H, Ph-H(CZ)), 8.2 (s, 2 H, Ph-H), 8.37 (d, J ) 8.2
Hz, 1 H, naphthalene-H), 8.42 (d, J ) 8.0 Hz, 1 H, naphthalene-
H), 8.45 (d, J ) 7.1 Hz, 1 H, naphthalene-H), 8.9 (s, 1 H, Ph-
H). MS (MALDI-TOF): m/z [M+ + Na] 2972.46, [M+ + K]
2988.39.
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Ack n ow led gm en t. This work was partially sup-
ported by NSFC/China (Project No.: 20106006), Educa-
tion Committee of Shanghai and Scientific Committee
of Shanghai. W.-H.Z. thanks the Foundation for Na-
tional Excellent Dissertation of P. R. China (Project No.
200143). Y.-Q.X. and Y.C. (SCUT) are grateful for
financial support from MOST (Project 2002CB613404).
Su p p or tin g In for m a tion Ava ila ble: The concise scheme
for the synthesis of the dendrimers, text giving experimental
details for synthesizing intermediates 3, 9, 10, 11, 12, and 13,
and a differential scanning calorimeter (DSC) trace of 4CZ-
NP3 (Figure S-1). This material is available free of charge via
the Internet at http://pubs.acs.org.
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