Design and construction of supramolecular polysulfurated metallodendrimers with various shapes and sizes via coordination-driven self-assembly

Article abstract of DOI:10.1016/j.tet.2013.04.058

A new family of 120 polysulfurated dipyridine donors have been successfully designed and synthesized, from which a series of novel rhomboidal and hexagonal supramolecular polysulfurated metallodendrimers were prepared via coordination-driven self-assembly. The structures of the newly designed polysulfurated metallodendrimers were characterized by multinuclear NMR ( ¹H and ³¹P), mass spectrometry (CSI-TOF-MS), and elemental analysis. Moreover, the shape and size of these novel metallodendrimers were investigated with PM6 semi-empirical molecular orbital methods.

Full text of DOI:10.1016/j.tet.2013.04.058

Tetrahedron 69 (2013) 5981e5988
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Design and construction of supramolecular polysulfurated
metallodendrimers with various shapes and sizes via
coordination-driven self-assembly
Nai-Wei Wu a, Quan-Jie Li b, Jing Zhang a, Jiuming He c, Jiang-Kun Ou-Yang a,
,
Hongwei Tan b, Zeper Abliz c, Hai-Bo Yang a
*
a Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 N.
Zhongshan Road, Shanghai 200062, PR China
b Department of Chemistry, Beijing Normal University, Beijing 100875, PR China
c Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, PR China
a r t i c l e i n f o
a b s t r a c t
A new family of 120ꢀ polysulfurated dipyridine donors have been successfully designed and synthesized,
Article history:
Received 25 January 2013
Received in revised form 1 April 2013
Accepted 15 April 2013
from which
a series of novel rhomboidal and hexagonal supramolecular polysulfurated metal-
lodendrimers were prepared via coordination-driven self-assembly. The structures of the newly designed
polysulfurated metallodendrimers were characterized by multinuclear NMR (1H and 31P), mass spec-
trometry (CSI-TOF-MS), and elemental analysis. Moreover, the shape and size of these novel metal-
lodendrimers were investigated with PM6 semi-empirical molecular orbital methods.
Ó 2013 Elsevier Ltd. All rights reserved.
Available online 3 May 2013
1. Introduction
Dendrimers have a highly branched, three-dimensional archi-
tecture, composed of several dendritic wedges that extend outward
Coordination-driven self-assembly1 has proven to be a particu-
larly powerful tool for the construction of delicate supramolecular
two-dimensional (2-D) and three-dimensional (3-D) metal-
containing architectures with well-defined shape and size. Metal-
eligand directional bonds between two or more predesigned mo-
lecular building blocks often feature significant synthetic
advantages such as few steps, fast and facile construction of the
final products, and inherently self-correcting, defect-free assembly.
Thus by employing coordination-driven self-assembly, a great
number of well-defined 2-D and 3-D metal-containing structures
have been successfully designed and constructed during the past
few decades.2 However, the most 2-D metal-containing polygons
were built from simple, fairly inert building blocks that are often
aliphatic or aromatic in nature. Therefore many self-assembled
metallocycles are, for the most part, unfunctionalized. Recently,
substantial efforts have focused on incorporating suitable func-
tional moieties onto the resulted supramolecular complexes with
the aim to the fabrication of functional artificial molecular devices.3
For instance, an exo-functionalization approach has been widely
utilized to prepare discrete supramolecular metal-containing as-
semblies functionalized with crown ether, ferrocene, and hydro-
phobic and hydrophilic units that have been distributed within
building blocks.4
from an internal core.5 In the past few decades, the design and
synthesis of diverse dendrimers have evolved to be one of the most
important subjects within modern chemistry not only because of
their aesthetically pleasing structures but also as a result of their
various applications in catalysis, encapsulation and delivery, and
materials science.6 It should be noted that, since the pioneering
work by Newkome and co-workers7 and Balzani and co-workers8
in the early 1990s, metallodendrimers9 have received consider-
able attention because of their potential application in catalysis,10
biological mimetics,9l,11 and photo- and electrochemistry.12 For
example, we have previously reported the self-assembly of a vari-
ety of metallodendrimers with cavities of various shapes and sizes
such as rhomboids, triangle, and hexagons.4f,13 Moreover, Schalley
and co-workers have synthesized a family of new metallodendritic
0
ꢀ
squares from 4,4 -bipyridines functionalized with Frechet dendrons
and (dppp)-Pt(II) or Pd(II) triflate.14 Very recently, Newkome and
co-workers have reported the synthesis and photophysical prop-
erties of a series of new dendron-functionalized bis(terpyridine)-
iron(II) or -cadmium(II) metallomacrocycles.15
During the past few decades, a new family of polysulfurated
aromatic dendrimers have received considerable attention be-
cause of their unique structures and potential application in
photo- and electrochemistry.16 The investigation of these den-
drons containing thiol groups opened a door to some novel and
rare sulfur-containing arenes. For example, the synthesis and
* Corresponding author. E-mail address: hbyang@chem.ecnu.edu.cn (H.-B. Yang).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.04.058

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N.-W. Wu et al. / Tetrahedron 69 (2013) 5981e5988
characterization of a novel class of dendrimers consisting of
a polysulfurated pyrene core were presented by Gingras’ group.16a
It was found that their photophysical behavior and redox prop-
erties could be fine-tuned by the length of their branches. More-
over, a great deal of polysulfurated dendrimers with various
molecular shapes such as asterisks, chains, wheels, and windmills
were reported.16b Stimulated by our previous successful examples
of supramolecular metallodendrimers,4f,13 we envisioned that the
construction of a new family of polysulfurated dendrimers with
well-designed and controlled metal-containing rings would be
realized by the proper choice of subunits with predefined angles
and symmetry. This study could likely give rise to the design and
synthesis of novel polysulfurated dendritic species with inspired
functionality arising from their unique interior cavities and den-
dritic exteriors. Herein, we report our results on the self-assembly
of polysulfurated metallodendrimers possessing rings of various
size and shape at the core from newly designed [G-0]e[G-2] 120ꢀ
polysulfurated dendritic donors 3aec (Fig. 1).
2. Results and discussion
2.1. Synthesis of [G-0]e[G-2] 120ꢀ Polysulfurated Dendritic
Donors 3aec
The new 120ꢀ polysulfurated dendritic donors can be easily
synthesized in two steps as shown in Scheme 1. The polysulfurated
dendrimers were introduced by a nucleophilic substituting reaction
of 1,3,5-tribromobenzene with the corresponding thiolate of the
dendrimers.17 The selectivity for substituting monobromide of
1,3,5-tribrotnobenzene was achieved through using a controlled
amount of thiolate. From dendritic 3,5-dibromobenzene de-
rivatives 2aec, the desired 120ꢀ dendritic donor building blocks
3aec were obtained by the coupling reaction with 4-
ethynylpyridine in satisfactory yields in the presence of Pd(PPh3)4
and CuI as catalysts. The molecular structures of polysulfurated
dendritic precursors 3aec were well characterized by using mul-
tiple nuclear NMR (1H and 13C) and mass spectrometry.
Fig. 1. Molecular structures of [G-0]e[G-2] 120ꢀ polysulfurated dendritic donors 3aec.
Scheme 1. Synthesis of [G-0]e[G-2] 120ꢀ polysulfurated dendritic donors 3aec.

N.-W. Wu et al. / Tetrahedron 69 (2013) 5981e5988
5983
2.2. Self-assembly of [G-0]e[G-2] polysulfurated dendritic
rhomboids 5aec
m/z¼1135.01 for 5b, and m/z¼1442.39 for 5c), where M represents
the intact [2þ2] assemblies, were observed. These peaks were
isotopically resolved, and they agree very well with their respective
theoretical distribution (Fig. 4).
In general, the shape of an individual two-dimensional polygon
is determined by the value of the turning angle within its angular
components.1aec For example, the combination of 60ꢀ units with
complementary 120ꢀ linking components will yield a molecular
rhomboid.13c With the newly designed 120ꢀ polysulfurated den-
dritic precursors in hand, the self-assembly of polysulfurated
metallodendrimers with rhomboidal cavities was investigated.
Stirring the [G-0]e[G-2] 120ꢀ angular donors 3aec with an equi-
molar amount of the known 60ꢀ angular acceptor, 2,9-(trans-
Pt(PEt3)2NO3)2-phenanthrene (4),2h in CD2Cl2 for 1 h resulted in the
formation of [2þ2] rhomboidal metallodendrimers 5aec, re-
spectively (Scheme 2).
2.3. Self-assembly of hexagonal polysulfurated metal-
lodendrimers 7aec
According to the ‘directional bonding’ model and the ‘symmetry
interaction’ model,1a,b discrete molecular hexagons can be prepared
via the combination of two complementary ditopic building blocks A2
and X2, each incorporating 120ꢀ angles between their coordination
sites, leading to the formation of hexagonal structures of type A23X32.18a
Recently, we have reported the construction of dendritic multi-
ferrocenyl hexagons by using this strategy.13a In order to extend the
S
S
S
S
S
S
S
S
Et3P
ONO2
Pt
S
[2+2]
PEt3
2
S
)
S
S
°
2
+
CH2Cl2
PEt3
Pt
ONO2
Et3P
S
S
4
S
3a–c
4
S
S
S
5a–c
Scheme 2. Cartoon representations of the formation of rhomboidal polysulfurated metallodendrimers 5aec from 120ꢀ polysulfurated dendritic donors 3aec and 60ꢀ di-platinum
acceptor 4.
Multinuclear NMR (1H and 31P) analysis of [G-0]e[G-2] assem-
blies 5aec exhibited very similar characteristics, which all sug-
gested the formation of discrete, highly symmetric polysulfurated
metallodendrimers with rhomboidal cavities. The 31P{1H} NMR
spectra of the [G-0]e[G-2] assemblies 5aec displayed a sharp
singlet (ca. 12.5 ppm) shifted upfield from the signal of the starting
platinum acceptor 4 by approximately 6.2 ppm (Fig. 2). This change,
as well as the decrease in coupling of the flanking 195Pt satellites
(ca.
D
1JPPt¼ꢁ134 Hz), is consistent with electron back-donation
from the platinum atoms. Examination of the 1H NMR spectra
(Fig. 3 and Supplementary data) also indicated the existence of
highly symmetric structures. In the 1H NMR spectrum of each as-
sembly, the
0.1e0.7 ppm downfield shifts, and the
a
-hydrogen nuclei of the pyridine rings exhibited
-hydrogen nuclei showed
b
about 0.3e0.6 ppm downfield shifts, due to the loss of electron
density that occurs upon coordination of the pyridine N atom with
the Pt(II) metal center. Notably, two doublets were found for
a-
hydrogen nuclei and
b
-hydrogen nuclei on pyridine rings in the 1H
NMR spectrum of rhomboidal polysulfurated metallodendrimers.
This observation might be attributed to the hindered rotation about
the PteN(pyridyl) bond that has been reported previously.13d
The structures of the rhomboidal metallodendrimers 5aec have
also been confirmed by cold-spray ionization mass (CSI-TOF-MS),
which allows the assemblies to remain intact during the ionization
process while obtaining the high resolution required for isotopic
distribution. In the CSI-TOF-MS spectra of the [G-0]e[G-2] assem-
blies 5aec, peaks attributable to the loss of nitrate counterions,
[Mꢁ2NO3]2þ (m/z¼1503.49 for 5a, m/z¼1733.51 for 5b, and
m/z¼2194.56 for 5c) and [Mꢁ3NO3]3þ (m/z¼981.66 for 5a,
Fig. 2. Partial 31P{1H} NMR spectra (400 MHz, CD2Cl2, 298 K) of 60ꢀ di-Pt(II) acceptor 4
(A) and polysulfurated dendritic rhomboids (for [G-0] 5a, B; for [G-1] 5b, C; for [G-2]
5c, D).

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N.-W. Wu et al. / Tetrahedron 69 (2013) 5981e5988
indicated by the appearance of a sharp singlet (ca. 13.3 ppm) with
concomitant 195Pt satellites, shifted upfield by ca. 6.0 ppm as
compared to 6 (Fig. 5). As expected, a decrease in coupling of the
flanking 195Pt satellites was also observed (ca.
D
1JPPt¼ꢁ148 Hz),
lending the further support to the formation of the hexagonal
polysulfurated metallodendrimers 7aec. In the 1H NMR spectra of
metallodendrimers 7aec, the
a-H and b-H of the pyridine rings
exhibited ca. 0.2e0.3 ppm and ca. 0.4e0.5 ppm downfield shifts,
respectively, relative to free ligands 3aec (Fig. 6). In contrast to the
results for rhomboidal polysulfurated metallodendrimers 5aec, the
1H NMR spectra of 7aec showed only one doublet for the
a-H and
b-H protons of the pyridine ring linked to the Pt(II) center.
The structures of the hexagonal metallodendrimers have been
further confirmed by CSI-TOF-MS spectrometry and elemental
analysis as well. However, compared to the previous rhomboidal
polysulfurated metallodendrimers 5aec, it has proven more diffi-
cult to get strong mass signals for the charged hexagons 7aec on
account of their larger molecular weight even under the CSI-TOF-
MS conditions. With considerable effort, the peaks attributable to
[Mꢁ5OTf]5þ (m/z¼897.08 for 7a, m/z¼1035.52 for 7b, m/z¼1311.55
for 7c) were observed, where M represents the intact [3þ3] as-
semblies. These peaks were isotopically resolved, and they agree
with their respective theoretical distribution, although the resolu-
tion is not as good as that in the case of rhomboidal polysulfurated
metallodendrimers 5aec (see Supplementary data).
Fig. 3. Partial 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of [G-2] polysulfurated
dendritic donor 3c (A) and [G-2] polysulfurated dendritic rhomboid 5c (B).
scope of this approach to the construction of hexagonal polysulfurated
metallodendrimers, we have investigated the self-assembly of 120ꢀ
polysulfurated dendritic donors 3aec with 120ꢀ di-platinum acceptor
6. When the [G-0]e[G-2] 120ꢀ angular donor subunits 3aec were
reacted with the 120ꢀ ketone di-Pt(II) acceptor 618b in CD2Cl2 at room
temperature, the [3þ3] hexagonal polysulfurated metallodendrimers
7aec was formed, respectively (Scheme 3).
31P{1H} NMR analysis of the reaction mixtures 7aec is consis-
tent with the formation of a single, highly symmetric species, as
As mentioned previously, the [3þ3] discrete hexagonal struc-
tures can be self-assembled by combining three 120ꢀ pyridyl donor
Fig. 4. Theoretical (top) and experimental (bottom) CSI-TOF-MS spectra of polysulfurated dendritic rhomboids (for [G-0] 5a, A; for [G-1] 5b, B; for [G-2] 5c, C).
S
S
S
S
S
S
O
S
S
S
[3+3]
Et3P
Pt
PEt3
Pt
S
S
S
)
3
3
°
CH2Cl2
S
S
S
+
TfO
OTf
PEt3
Et3P
S
S
S
S
S
6
3a–c
6
S
S
S
7a–c
Scheme 3. Cartoon representations of formation of hexagonal polysulfurated metallodendrimers 7aec from 120ꢀ polysulfurated dendritic donors 3aec and 120ꢀ di-platinum
acceptor 6.

N.-W. Wu et al. / Tetrahedron 69 (2013) 5981e5988
5985
have proven to be unsuccessful to date. Thus PM6 semi-empirical
molecular orbital method19 was employed to optimize the geom-
etry of all polysulfurated metallodendrimers. In the case of 5aec,
the optimized structure of each assembly featured a very similar,
roughly planar rhomboidal ring at the core surrounded by flexible
polysulfurated dendrons. Moreover, it was found that the rhom-
boidal polysulfurated metallodendrimers 5aec possess a well-
defined rhombus structure with a 2.4ꢂ1.3 nm cavity in average
(Fig. 7A). With the increase of the dendron generation, the external
dimensions of the rhomboidal structures increased (5a,
3.1ꢂ3.0 nm; 5b, 4.1ꢂ3.0 nm; 5c, 4.6ꢂ3.1 nm). The similar results
were observed in the case of the hexagonal polysulfurated metal-
lodendrimers 7aec. For example, in the case of [G-2] hexagonal
polysulfurated metallodendrimers 7c (Fig. 7B), the hexagonal ring-
shaped metallodendrimer has an internal radius of approximately
1.4 nm and an average outer dendron radius of 3.2 nm. More
simulated geometry information about the rhomboidal and hex-
agonal polysulfurated metallodendrimers 5aec and 7aec could be
found in Supplementary data.
3. Conclusion
In summary, we have designed and synthesized a new family of
120ꢀ polysulfurated dendritic donor subunits, from which novel
rhomboidal and hexagonal polysulfurated metallodendrimers
5aec and 7aec can be easily formed via coordination-driven self-
assembly. All polysulfurated metallodendrimers were character-
ized with multinuclear NMR, CSI-TOF-MS, and elemental analysis.
Their structural properties have been studied by using PM6 semi-
empirical molecular orbital methods. Hence, we have demon-
strated again that highly convergent synthetic protocols based on
the simultaneous assembly of appropriate predetermined building
block allow the rapid construction of novel polysulfurated metal-
lodendrimers. In particular, this approach is capable of preparing
a variety of metallodendrimers with different shape and size
through the proper choice of subunits with predefined angles and
symmetry, which enriches the library of polysulfurated arenes.
Further studies on their applications of these supramolecular pol-
ysulfurated metallodendrimers are in progress.
Fig. 5. Partial 31P{1H} NMR spectra (400 MHz, CD2Cl2, 298 K) of 120ꢀ di-Pt(II) acceptor
6 (A) and [3þ3] hexagons [G-0] 7a (B), [G-1] 7b (C), [G-2] 7c (D).
4. Experimental section
4.1. General information
Fig. 6. Partial 1H NMR spectra (400 MHz, CD2Cl2, 298 K) of [G2]-donor 3c (A) and [G-2]
polysulfurated dendritic hexagon 7c (B).
All solvents were dried according to standard procedures and all
of them were degassed under N2 for 30 min before use. Reagents
were used as purchased. All air-sensitive reactions were carried out
under argon atmosphere. 1H NMR, 13C NMR, and 31P NMR spectra
were recorded on Bruker 400 MHz spectrometer (1H: 400 MHz;
13C: 100 MHz; 31P: 161.9 MHz) at 298 K. The 1H and 13C NMR
chemical shifts are reported relative to residual solvent signals, and
31P NMR resonances are referenced to an internal standard sample
building blocks and three 120ꢀ di-platinum acceptors.18a Further-
more, recent studies have indicated that the addition of functional
groups at the vertices of individual building units, such as ferrocene
and crown ether moieties, does not hinder the formation of [3þ3]
self-assembled supramolecular hexagons.4b,13a In this study, the
sharp NMR signals in both the 31P{1H} and 1H NMR spectra along
with the solubility of these species ruled out the formation of
oligomers. Moreover, the CSI-TOF-MS results ensure that only
[3þ3] hexagonal polysulfurated metallodendrimers are formed in
each self-assembly.
of 85% H3PO4
(Hz) and chemical shifts (
(
d
0.0). Coupling constants (J) are denoted in hertz
) in parts per million (ppm). Multiplici-
d
ties are denoted as follows: s¼singlet, d¼doublet, m¼multiplet,
br¼broad.
The CSI-TOF-MS spectra were acquired using an AccuTOFCS
mass spectrometer (JMS-T100CS, JEOL, Tokyo, Japan). All the com-
plexes were prepared and diluted to about 0.1
CH2Cl2, and the solution was delivered to the ion source by an in-
fusion syringe pump at a flow rate of 20 L/min. The needle voltage
mg/mL in a solution of
2.4. Molecular simulation
m
Large supramolecular coordination-compounds and flexible,
high generation dendrimers often prove difficult to crystallize. All
attempts to grow X-ray quality single crystals of the rhomboidal
and hexagonal polysulfurated metallodendrimers 5aec and 7aec
was set at 3000 V; the orifice 1 voltage was set at 40 V; the orifice 2
voltage was 20 V. The flow rate of spray gas was 2.5 L/min at room
temperature. The resolution of the mass analyzer was optimized at
6000 (50% peak). Mass scan range was set at 100e3000 Da.

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N.-W. Wu et al. / Tetrahedron 69 (2013) 5981e5988
Fig. 7. Simulated molecular models of the [G-2] polysulfurated dendritic rhomboid 5c (A) and [G-2] polysulfurated dendritic hexagon 7c (B).
4.2. General procedure for the synthesis of 2aec
1H), 7.34 (d, J¼2.0 Hz, 2H), 7.27 (d, J¼8.0 Hz, 8H), 7.14 (d, J¼8.0 Hz,
8H), 7.04 (d, J¼1.6 Hz, 2H), 7.02 (t, J¼1.6 Hz, 2H), 6.86e6.84 (m, 6H),
Synthesis of compound 2. Under an atmosphere of nitrogen, [G-
n]-SH17 (for G-0, 394 mg, 3.18 mmol; for G-1, 443 mg, 1.25 mmol;
for G-2, 145 mg, 0.178 mmol) and appropriate NaH were placed in
a 50 mL Schlenk flask followed by 10e15 mL of anhydrous DMF. The
mixture was stirred for 10 min at room temperature. The appro-
priate 1.0 equiv compound 1 was then added under nitrogen. The
reaction was continued at 80 ꢀC for another 12 h and then
quenched by 10 mL of water, extracted with ethyl acetate, and dried
with MgSO4. The solvent was removed by evaporation on a rotary
evaporator. The residue was purified by column chromatography
on silica gel (petroleum ether/CH2Cl2z10:1) to give compounds
2aec.
2.34 (s, 12H). 13C NMR (CD2Cl2, 100 MHz):
d 141.57, 139.67, 138.82,
136.85, 136.54, 134.34, 133.87, 132.61, 132.30, 132.21, 131.12, 129.52,
128.44, 127.30, 124.20, 21.80. MALDI-TOF-MS: m/z (%)¼1046.0 (Mþ,
40.58), 1047.9 [(Mþ2H)þ, 100.00]. MALDI-HRMS calcd for
C52H40Br2S7: 1045.9542, found: 1045.9536.
4.3. General procedure for the preparation of [G-0]e[G-2]
dendritic precursors 3aec
Under an atmosphere of nitrogen, 10 mL THF and 10 mL i-Pr2NH
were added to a mixture of 4-ethynylpyridine hydrochloride
(558 mg, 4.00 mmol), compounds 2aec (2a, 800 mg, 2.25 mmol;
2b, 669 mg, 1.14 mmol; 2c, 129 mg, 0.35 mmol), 0.05 equiv
Pd(PPh3)4, and 0.05 equiv CuI in 100 mL Schlenk flask. The mixture
was stirred at 65 ꢀC for 12 h. Then insoluble materials were filtrated
through filter paper and the solvent was removed by evaporation
on a rotary evaporator. Column chromatography with CH2Cl2/
methanol (50:1) as eluent afforded compounds 3aec.
4.2.1. Compound 2a. Yield: 71%. Colorless oil. Rf¼0.80 (petroleum
ether). 1H NMR (CDCl3, 400 MHz):
d
7.42 (t, J¼1.2 Hz, 1H), 7.38 (d,
J¼8.4 Hz, 2H), 7.22e7.19 (m, 4H), 2.39 (s, 3H). 13C NMR (CDCl3,
100 MHz):
d 142.67, 139.15, 133.92, 131.00, 130.47, 128.86, 127.87,
123.09, 21.21. MS (EI): m/z (%)¼356 (Mþ, 52.55), 358 [(Mþ2H)þ,
100.00], 198 (66.78). HRMS (EI) calcd for C13H10Br2S: 355.8870,
found: 355.8871.
4.3.1. Compound 3a. Yield: 84%. Gray solid. Rf¼0.53 (CH2Cl2/
methanol 50:1). Mp: 136 ꢀC. 1H NMR (CD2Cl2, 400 MHz):
d 8.60 (d,
4.2.2. Compound 2b. Yield: 67%. Colorless oil. Rf¼0.51 (petroleum
J¼6.0 Hz, 4H), 7.55 (t, J¼1.6 Hz, 1H), 7.41e7.36 (m, 8H), 7.25 (d,
ether/CH2Cl2 8:1). 1H NMR (CDCl3, 400 MHz):
d
7.49 (t, J¼1.6 Hz,
J¼8.0 Hz, 2H), 2.38 (s, 3H). 13C NMR (CD2Cl2, 100 MHz):
d 150.13,
1H), 7.29e7.26 (m, 6H), 7.15 (d, J¼2.0 Hz, 4H), 6.90 (t, J¼1.6 Hz, 1H),
140.11, 139.36, 133.87, 132.73, 132.04, 130.81, 130.74, 129.10, 125.69,
123.69, 92.16, 88.24, 21.30. MS (EI): m/z (%)¼402 (Mþ, 100.00), 403
[(Mþ1H)þ, 32.00]. HRMS (EI) calcd for C27H18N2S: 402.1191, found:
402.1192.
6.78 (d, J¼1.6 Hz, 2H), 2.37 (s, 6H). 13C NMR (CDCl3, 100 MHz):
d
140.93, 139.07, 138.72, 135.46, 133.72, 132.53, 131.80, 130.30,
128.39, 127.12, 126.07, 123.15, 21.24. MS (EI): m/z (%)¼586 (Mþ,
47.58), 587 [(MþH)þ, 14.90], 588 [(Mþ2H)þ, 100.00], 358 (36.90),
198 (88.90). HRMS (EI) calcd for C26H20Br2S3: 585.9094, found:
585.9097.
4.3.2. Compound 3b. Yield: 77%. Gray solid. Rf¼0.48 (CH2Cl2/
methanol 50:1). Mp: 164 ꢀC. 1H NMR (CD2Cl2, 400 MHz):
d 8.62 (d,
J¼5.6 Hz, 4H), 7.62 (t, J¼1.6 Hz, 1H), 7.46 (d, J¼1.6 Hz, 2H), 7.42 (d,
J¼5.6 Hz, 4H), 7.28 (d, J¼8.0 Hz, 4H), 7.14 (d, J¼8.0 Hz, 4H), 6.83 (s,
1H), 6.82 (d, J¼1.6 Hz, 2H), 2.39 (s, 6H). 13C NMR (CDCl3, 100 MHz):
4.2.3. Compound 2c. Yield: 37%. Colorless oil. Rf¼0.48 (petroleum
ether/CH2Cl2 3:1). 1H NMR (CD2Cl2, 400 MHz):
d
7.58 (t, J¼1.6 Hz,

N.-W. Wu et al. / Tetrahedron 69 (2013) 5981e5988
5987
d
150.32, 141.25, 139.40, 136.93, 136.55, 135.17, 134.11, 134.07, 130.81,
3b, 2.84 mg, 0.00449 mmol; for 3c, 4.90 mg, 0.00449 mmol) drop
by drop with continuous stirring (10 min). The reaction mixture
was stirred 1 h at room temperature. The solution was evaporated
to dryness, and the product was collected.
130.69, 128.77, 127.06, 126.00, 125.82, 124.12, 91.77, 88.49, 21.35. MS
(EI): m/z (%)¼632 (Mþ, 100.00), 633 [(MþH)þ, 50.26], 634
[(Mþ2H)þ, 22.90]. HRMS (EI) calcd for C40H28N2S3: 632.1415,
found: 632.1414.
4.5.1. Compound 7a. Yield: 99%. Gray solid. 1H NMR (CD2Cl2,
4.3.3. Compound 3c. Yield: 67%. Pale yellow solid. Rf¼0.44 (CH2Cl2/
400 MHz):
d
8.70 (d, J¼5.6 Hz, 4H), 7.81e7.77 (m, 5H), 7.56e7.43 (m,
methanol 50:1). Mp: 183 ꢀC. 1H NMR (CD2Cl2, 400 MHz):
d 8.64 (d,
12H), 7.29 (d, J¼8.0 Hz, 2H), 2.41 (s, 3H), 1.36 (br, 24H),1.18e1.10 (m,
J¼6.0 Hz, 4H), 7.69 (t, J¼1.2 Hz, 4H), 7.50 (t, J¼1.2 Hz, 4H), 7.40 (d,
J¼6.0 Hz, 4H), 7.28 (d, J¼8.0 Hz, 8H), 7.12 (d, J¼8.0 Hz, 8H),
7.02e7.00 (m, 3H), 6.87 (t, J¼1.6 Hz, 2H), 6.84 (d, J¼1.6 Hz, 4H), 2.36
36H). 31P NMR (CD2Cl2, 161.9 MHz):
d
13.30 (s, JPteP¼2652.41 Hz).
CSI-TOF-MS [Mꢁ5OTf]5þ
,
897.08. Anal. Calcd for C198H258
F18N6O21P12Pt6S9: C, 45.46; H, 4.92; N, 1.61. Found: C, 45.58; H, 5.17;
N, 1.59.
(s, 12H). 13C NMR (CD2Cl2, 100 MHz):
d 150.26, 141.14,139.28,138.19,
137.63, 136.31, 136.16, 135.26, 134.72, 133.90, 131.65, 131.32, 130.89,
130.72, 129.12, 127.90, 126.79, 125.95, 124.43, 91.84, 88.81, 21.39.
LCMS (ESI): m/z (%)¼1094 [(Mþ2H)þ, 10.00]. Anal. Calcd for
C66H48N2S7: C, 72.49; H, 4.42; N, 2.56. Found: C, 72.86; H, 4.81; N,
2.84.
4.5.2. Compound 7b. Yield: 98%. Gray solid. 1H NMR (CD2Cl2,
400 MHz):
d
8.72 (d, J¼5.6 Hz, 4H), 7.88e7.84 (m, 5H), 7.56e7.53 (m,
9H), 7.30 (d, J¼8.0 Hz, 4H), 7.17 (d, J¼8.0 Hz, 4H), 6.91 (s, 2H), 6.82 (s,
1H), 2.36 (s, 6H),1.36 (br, 24H),1.19e1.11 (m, 36H). 31P NMR (CD2Cl2,
161.9 MHz):
d
13.38 (s, JPteP¼2647.06 Hz). CSI-TOF-MS [Mꢁ5OTf]5þ
,
4.4. General procedure for the self-assembly of 5aec
1035.52; Anal. Calcd for C237H228F18N6O21P12Pt6S15: C, 48.07; H,
4.90; N, 1.42. Found: C, 47.81; H, 4.95; N, 1.63.
CD2Cl2 (1.0 mL) was added to a mixture of nitrate salts 4 (5.0 mg,
0.00430 mmol) and the appropriate [G-0]e[G-2] dendritic pre-
cursors 3aec (for 3a, 1.73 mg, 0.00430 mmol; for 3b, 2.71 mg,
0.00430 mmol; for 3c, 4.70 mg, 0.00430 mmol). The reaction
mixture was then stirred for 1 h at room temperature, upon which
starting materials were completely dissolved and the reaction
mixture attained a gray color. The self-assembly was monitored by
1H and 31P NMR spectroscopy and determined to be complete. The
deuterated solvent was evaporated to dry and the crude product
was obtained.
4.5.3. Compound 7c. Yield: 98%. Gray solid. 1H NMR (CD2Cl2,
400 MHz):
d
8.69 (d, J¼5.6 Hz, 4H), 7.92e7.81 (m, 5H), 7.58e7.53 (m,
10H), 7.26 (d, J¼8.0 Hz, 8H), 7.14 (d, J¼8.0 Hz, 8H), 6.81 (s, 4H), 6.80
(s, 2H), 2.34 (s, 12H), 1.35 (br, 24H), 1.17e1.09 (m, 36H). 31P NMR
(CD2Cl2, 161.9 MHz):
d
13.25 (s, JPteP¼2637.67 Hz). CSI-TOF-
MS [Mꢁ5OTf]5þ, 1311.55. Anal. Calcd for C315H348F18N6O21P12Pt6S27
:
C, 51.80; H, 4.80; N, 1.15. Found: C, 51.90; H, 5.20; N, 1.29.
Acknowledgements
4.4.1. Compound 5a. Yield: 99%. Gray solid. 1H NMR (CD2Cl2,
This work was financially supported by NSFC/China (No.
21132005 and 91027005), Shanghai Shuguang Program (No.
09SG25), RFDP (No. 20100076110004) of Higher Education of
China, Fok Ying Tung Education Foundation (No. 131014), and the
Program for New Century Excellent Talents in University of Min-
istry of Education of China (NCET-09-0358).
400 MHz):
d
9.30 (d, J¼5.6 Hz, 4H), 8.79 (s, 4H), 8.70 (d, J¼5.6 Hz,
4H), 7.96 (d, J¼5.6 Hz, 4H), 7.83 (s, 2H), 7.73 (d, J¼5.6 Hz, 4H),
7.60e7.53 (m, 12H), 7.46 (d, J¼8.0 Hz, 4H), 7.30 (d, J¼8.0 Hz, 4H),
2.42 (s, 6H), 1.36 (m, 48H), 1.18e1.10 (m, 72H). 31P NMR (CD2Cl2,
161.9 MHz):
d
12.65 (s, JPteP¼2705.67 Hz). CSI-TOF-
MS [Mꢁ2NO3]2þ, 1503.49; [Mꢁ3NO3]3þ, 981.66. Anal. Calcd for
C130H172N8O12P8Pt4S2$CH2Cl2: C, 48.92; H, 5.54; N, 3.58. Found: C,
48.86; H, 5.52; N, 3.57.
Supplementary data
4.4.2. Compound 5b. Yield: 98%. Gray solid. 1H NMR (CD2Cl2,
1H NMR, 13C NMR spectra of 2aec, 3aec and 1H NMR, 31P NMR
spectra of 5aec, 7aec, and CSI-TOF-MS of 7aec. Supplementary
data related to this article can be found in the online version, at
http://dx.doi.org/10.1016/j.tet.2013.04.058.
400 MHz):
d
9.39 (d, J¼6.0 Hz, 4H), 8.83 (s, 4H), 8.72 (d, J¼6.0 Hz,
4H), 8.01 (d, J¼7.2 Hz, 4H), 7.91 (t, J¼1.2 Hz, 2H), 7.76 (d, J¼7.2 Hz,
4H), 7.61e7.58 (m,12H), 7.31 (d, J¼8.0 Hz, 8H), 7.18 (d, J¼8.0 Hz, 8H),
6.90 (d, J¼1.6 Hz, 4H), 6.84 (t, J¼1.6 Hz, 2H), 2.37 (s, 12H), 1.37 (br,
48H), 1.19e1.11 (m, 72H). 31P NMR (CD2Cl2, 161.9 MHz):
d
12.51 (s,
1733.51;
References and notes
JPteP¼2713.77
Hz).
CSI-TOF-MS
[Mꢁ2NO3]2þ
,
[Mꢁ3NO3]3þ, 1135.01. Anal. Calcd for C156H192N8O12P8Pt4S6: C,
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4.4.3. Compound 5c. Yield: 97%. Gray solid. 1H NMR (CD2Cl2,
400 MHz):
d
9.39 (d, J¼6.0 Hz, 4H), 8.83 (s, 4H), 8.72 (d, J¼6.0 Hz,
4H), 8.01 (d, J¼7.2 Hz, 4H), 7.91 (t, J¼1.2 Hz, 2H), 7.76 (d, J¼7.2 Hz,
4H), 7.61e7.58 (m,12H), 7.31 (d, J¼8.0 Hz, 8H), 7.18 (d, J¼8.0 Hz, 8H),
6.90 (d, J¼1.6 Hz, 4H), 6.84 (t, J¼1.6 Hz, 2H), 2.37 (s, 12H), 1.37 (br,
48H), 1.19e1.11 (m, 72H). 31P NMR (CD2Cl2, 161.9 MHz):
d
12.46 (s,
2194.56;
JPteP¼2716.68
Hz).
CSI-TOF-MS
[Mꢁ2NO3]2þ
,
[Mꢁ3NO3]3þ, 1442.39. Anal. Calcd for C208H232N8O12P8Pt4S14: C,
55.35; H, 5.18; N, 2.48. Found: C, 55.30; H, 5.21; N, 2.29.
4.5. General procedure for the self-assembly of 7aec
To a 0.5 mL CD2Cl2 solution of triflate 6 (6.02 mg, 0.00449 mmol)
was added a 0.5 mL CD2Cl2 solution of the appropriate [G-0]e[G-2]
dendritic donor precursor 3aec (for 3a, 1.80 mg, 0.00449 mmol; for

5988
N.-W. Wu et al. / Tetrahedron 69 (2013) 5981e5988
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