Platinum acetylide complexes containing iptycene as cores: A new family of unexpected efficient organometallic gelators

Article abstract of DOI:10.1021/om2002987

A new family of platinum acetylide derivatives containing iptycene building blocks end-capped with 3,4,5-tris(alkoxy)phenyl substituents has been successfully synthesized. The structure of the newly designed complexes was characterized by multinuclear NMR

Full text of DOI:10.1021/om2002987

ARTICLE
pubs.acs.org/Organometallics
Platinum Acetylide Complexes Containing Iptycene as Cores: A New
Family of Unexpected Efficient Organometallic Gelators
Jing Zhang,† Xing-Dong Xu,† Li-Jun Chen,† Qi Luo,† Nai-Wei Wu,† De-Xian Wang,‡ Xiao-Li Zhao,†
and Hai-Bo Yang*,†
†Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University,
3663 N. Zhongshan Road, Shanghai 200062, People's Republic of China
‡Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function,
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
S Supporting Information
b
ABSTRACT: A new family of platinum acetylide derivatives containing
iptycene building blocks end-capped with 3,4,5-tris(alkoxy)phenyl
substituents has been successfully synthesized. The structure of the
newly designed complexes was characterized by multinuclear NMR
(1H, 31P, and 13C) and mass spectroscopy and elemental analysis.
Unexpectedly, all compounds presented good gel formation properties
in some common organic solvents. The morphology of the xerogels was
investigated by scanning electron microscopy (SEM). An investigation
using electronic absorption and emission spectra was carried out to
study the spectroscopic properties of all organometallic complexes in
both solution and gel states.
gel is a solid, jellylike material, which has a continuous
structure with macroscopic dimensions that are permanent
approach to the preparation of functional soft materials from
small building blocks.5
A
on the time scale of an analytical experiment.1 Usually, gels are
formed by warming a small amount of gelator in an appropriate
solvent until the solid is dissolved. When the solution is cooled to
below Tgel (temperature of gelation), the entire volume of the
solvent is immobilized and can support its own weight without
collapsing. In the most cases, it is believed that the phenomenon
of gelation arises from fibers becoming entangled and trapp-
ing solvent via surface tension. The physical characteristics of
gels can range from those of surfactants in solution to those of
polymers.2
Supramolecular gels containing metal-organic subunits have
currently attracted great interest. Conceptually, in comparison to
conventional organic gelators, there is no obvious difference of
a gelator containing a strongly bound metal ion within the
molecule. However, the introduction of a metal center, especially
a transition-metal center, into the skeletons of gelator molecules
can affect self-aggregation modes and allow additional scope for
tuning gel properties.6 For example, Adia and co-workers have
successfully synthesized an interesting class of trinuclear Au(I)
pyrazolate metallacyclic gels. Upon doping or dedoping of Ag(I)
ions, the gelÀsol phase transition showed a reversible switching
of redÀgreenÀblue luminescence.6i In addition, a new family of
organometallic gelators comprised of platinum(II) terpyridyl
alkynyl species has been reported by Yam’s group, which shows
drastic color and emission changes during solÀgel transitions.6j
However, in comparison to the considerable work on supramo-
lecular organogels, relatively few studies have explored the synth-
esis and properties of supramolecular gels consisting of metal-
organic subunits. Particularly, the construction of functionalized
organometallic gels is still challenging.
Recently, organogels prepared via a “bottom-up” strategy from
small- or medium-sized molecules have evolved to be one of the
most attractive subjects within supramolecular chemistry, due to
their potential applications in materials and biological fields.3 In
the process of organogelation, self-assembly has been proven to
play an essential role. Driven by noncovalent interactions, such as
hydrogen bonding, solvophobic interactions, πÀπ stacking,
electrostatic interactions, and van der Waals forces, the organic
gelator molecules self-assemble to form nanometer-scale fibrous
structures, which sequentially build up a micrometer-scale inter-
woven three-dimensional network entrapping solvent molecules.4
This process is spontaneous and can be easily controlled without
using technologically advanced techniques. By a small modifica-
tion of the structure of the gelator subunit or by changing the
experimental conditions, such as the polarity of the solvents, the
morphologies and the properties of the resulted organogels could
be finely tuned. This provides a simple, yet highly efficient
In the past decades, iptycene units have been extensively
explored in supramolecular chemistry and material sciences be-
cause of not only their three-dimensional, noncompliantstructures
but also their wide applications in the areas of electro-and
Received: April 6, 2011
Published: July 14, 2011
r
2011 American Chemical Society
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Scheme 1. Synthesis of Platinum Acetylide Derivatives
Containing Triptycene Building Blocks End-Capped with
3,4,5-Tris(alkoxy)phenyl Substituents 1aÀc
Figure 1. Chemical structures of the iptycene-containing platinum
acetylide organogelators 1aÀc and 2aÀc.
photochemistry, sensors, and molecular devices.7 Surprisingly,
until now, there has been no report on organometallic gelators
containing iptycene moieties, to the best of our knowledge. This
might be caused by the fact that iptycene groups usually prevent
effective packing during the formation of regular aggregates.
On the basis of our previous research8 on the synthesis and
utilization of platinum acetylide building blocks, we designed and
synthesized a new family of platinum complexes, in which the
iptycene groups were introduced into the platinum acetylide
frameworks, followed by the decoration of long alkyl chains on
two sides of the molecules (Figure 1). Unexpectedly, all newly
designed complexes featured efficient gel formation properties in
most nonpolar alkyl solvents and some polar solvents. Obviously,
this surprising result provides an opportunity to construct new
iptycene-containing organometallic gels.
Scheme 2. Synthesis of Platinum Acetylide Derivatives
Containing Pentiptycene Building Blocks End-Capped with
3,4,5-Tris(alkoxy)phenyl Substituents 2aÀc
Results and Discussion. The target molecules 1aÀc and
2aÀc were synthesized by two steps of cross-coupling reactions,
starting with the triptycene diacetylene and pentiptycene diace-
tylene, respectively (Schemes 1 and 2). The molecular structures
of compounds 1aÀc and 2aÀc were characterized with multi-
nuclear NMR (1H, 31P, and 13C) and mass spectroscopy and
elemental analysis. The multinuclear NMR analyses of 1aÀc and
2aÀc exhibited very similar characteristics, which all suggested
the formation of discrete, highly symmetric platinum acetylide
conjugates with triptycene or pentiptycene as cores. For instance,
the 31P{1H} NMR spectra of 1aÀc displayed a sharp singlet
(ca. 12.1 ppm) shifted downfield from that of the starting
platinum compound 4 by approximately 2.7 ppm due to electron
withdrawal by the large π-conjugated bridges. Similar results
were also observed in the case of 2aÀc. In addition, the 1H NMR
spectra of all complexes showed characteristic proton resonances
of 1,4-bis-substituted triptycene or pentiptycene in the bridge-
head area, one singlet at 6.01 ppm for 1aÀc, and one singlet at
5.93 ppm for 2aÀc, respectively.
PÀPtÀI angles in the ranges 84.9 and 95.6°, which might be
caused by the steric demand of the bulky triethylphosphine
ligands (Table 1). The C1ÀC2 bond was shorter than the CtC
bond in the compound end-capped with an acetylenylbenzene
group (the bond length is 1.221 Å).9 This difference may be
dictated by the acetylenylbenzene group, which makes the
C1ÀC2 bond more electron rich. A view of the unit cell packing
diagrams for 4 and 7 viewed along the a axis are also shown in
Figure 2. It is quite evident from the diagram that, due to the large
steric constraint imposed by the PEt3 groups and the iptycene
units, the distances between the nearest two platinum atoms
in the adjacent molecules are approximately 7.37 Å for 4 and
15.20 Å for 7, which exceed the distance for the existence of a
Unfortunately, all attempts to grow X-ray-quality single crys-
tals of the compounds 1aÀc and 2aÀc have proven unsuccessful.
However, single crystals of the precursors 4 and 7, suitable for
X-ray diffraction studies, were grown by slow vapor evaporation
of a solution of a solvent mixture (dichloromethane/methanol
1/1) at ambient temperature for 5À7 days. ORTEP representa-
tions of the structures of 4 and 7 are shown in Figure 2. The
platinum atoms in both complexes were found to adopt a slightly
distorted trans-square-planar geometry with CÀPtÀP and
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Figure 2. Crystal structures of precursors 4 (A) and 7 (B) and packing diagrams for 4 (C) and 7 (D) viewed along the a axis.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 4
and 7
the molecules in the gel state should be very similar to those of the
isolated molecules in solution.
The gelation properties of compounds 1aÀc and 2aÀc were
evaluated in various aromatic, nonaromatic, polar, and nonpolar
solvents. A weighed sample (2.0 μmol) was mixed with a solvent
(50 μL) in a capped vial. The mixture was then heated until the
solid was completely dissolved. Subsequently the clear solution
was cooled to 298 K (for 1b, 275 K) to form a gel. Surprisingly,
it was found that all compounds except 1a exhibited good
gel formation properties in the most nonpolar solvents such as
n-hexane, n-pentane, n-octane, etc. and some polar solvents such
as n-propanol. The organometallic gels melt to a clear nonviscous
solution that could be reversibly turned back to the gel state upon
cooling. Photographs of selected organometallic gels and their
corresponding solutions are shown in Figure 3.
The critical gelator concentrations (CGCs) of complexes
1aÀc and 2aÀc were determined by measuring the minimum
amount of compound required for the formation of a gel. In
comparison to the lowest molecular weight organic gelator
molecules, the CGCs of 1aÀc and 2aÀc were slightly higher.
For instance, the CGC of 1c in ethyl acetate is 24 mg/mL,
indicating that one molecule of 1c could entrap approximately
0.8 Â 103 solvent molecules. Considering the large molecular
weight of these compounds, for example, 2976 Da for 1c, the
CGCs obtained were still acceptable. It was obvious that the
compounds containing triptycene as cores can form gels more
Compound 4
Pt(1)ÀC(1)
Pt(1)ÀP(2)
C(1)ÀC(2)
1.944(6)
2.302(2)
1.204(9)
Pt(1)ÀP(1)
Pt(1)ÀI(1)
C(2)ÀC(3)
2.298(2)
2.6367(5)
1.436(8)
C(1)ÀPt(1)ÀI(1)
P(2)ÀPt(1)ÀI(1)
C(1)ÀPt(1)ÀP(2)
C(1)ÀC(2)ÀC(3)
176.7(2)
95.01(6)
85.8(2)
P(2)ÀPt(1)ÀP(1)
P(1)ÀPt(1)ÀI(1)
C(1)ÀPt(1)ÀP(1)
174.76(9)
90.16(7)
88.9(2)
179.4(7)
Compound 7
Pt(1)ÀC(1)
Pt(1)ÀP(2)
C(1)ÀC(2)
1.961(5)
2.3076(15)
1.208(7)
Pt(1)ÀP(1)
Pt(1)ÀI(1)
C(2)ÀC(3)
2.3081(16)
2.6427(4)
1.425(7)
C(1)ÀPt(1)ÀI(1)
P(2)ÀPt(1)ÀI(1)
C(1)ÀPt(1)ÀP(2)
C(1)ÀC(2)ÀC(3)
177.05(17)
95.60(4)
P(2)ÀPt(1)ÀP(1)
P(1)ÀPt(1)ÀI(1)
C(1)ÀPt(1)ÀP(1)
174.06(5)
90.17(4)
89.41(15)
84.90(15)
175.4(6)
PtÀPt interaction. Thus, the PtÀacetylide chains are well sepa-
rated in the crystal. It was expected that the optical properties of
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easily than those containing pentiptycene as the building block,
presumably due to the static hindrance. It is worth noting that
compounds 1b and 2b, due to their C12 alkoxy chain, could
generate transparent gels in a nonpolar solvent, which was quite
different from the case for other compounds. All the above results
demonstrate that the structural factors, including the shape of
the gelator molecules, have a dramatic influence on the formation
of the supramolecualr gels. The gelation properties of all six
compounds 1aÀc and 2aÀc are summarized in Table 2.
diameter of 4.6 μm was obtained, which was quite different from
its morphology in nonpolar solvent (Figure 4D). This outcome
again proved that by changing experimental conditions, such as
the polarity of solvents, the morphology of the resulted organo-
metallic gel could be tuned.
The electronic absorption spectra of compounds 1aÀc and
2aÀc in dilute dichloromethane solutions at 298 K exhibited
similar characteristics (Figure S14, Supporting Information).
The absorption spectra were dominated by a strong and rela-
tively broad band in the near-UV region (330À350 nm) with
weaker transitions at higher energy. The dominant absorption
band was assigned as the long-axis-polarized π,π* transition of
the PtÀacetylide chromophore. In comparison to 1aÀc, the
absorption spectra of complexes 2aÀc presented a small bath-
ochromic shift (ca. 20 nm) of the main absorption band peaks. In
addition, the emission spectra of compounds 1aÀc featured a
moderately intense emission band with a maximum at ∼510 nm.
In the case of 2aÀc, the predominant band was similar to those of
1aÀc but exhibited a blue shift about 20 nm. Interestingly, in
The aggregation structures of the xerogels (air-dried gels)
were investigated by scanning electron microscopy (SEM)
(Figure 4). The typical fibrous networks were observed in the
electron micrographs of xerogels 1c and 2c in hexane. For
instance, in the case of 1c, a three-dimensional (3D) network
comprised of entangled fibers with diameter of 260À900 nm
was found. Similarly, the xerogels of 2c from hexane exhibited a
dense network consisting of larger fibers with diameters of 570À
1550 nm. Interestingly, the morphologies of the xerogels 1c were
strongly dependent on the polarity of the tested solvents. For
example, in n-propanol, a globular morphology with a mean
Figure 3. (Top) Photographs of the gel forms of 1aÀc (aÀc) and 2aÀc
(dÀf) in hexane. (Bottom) Photographs of the gel (left) and sol (right)
forms of 2c in hexane.
Figure 4. SEM images of the xerogels of 1c in hexane (A), 2c in hexane
(B), 1c in n-propanol (C), and 1c in n-propanol at higher magnification(D).
Table 2. Summary of Gelation Propertiesa
solvent
1a
1b
1cc
2a
2b
2cc
cyclohexane
n-hexane
G (39.3)b
G (19.7)b
G (29.5)b
S
S
S
S
P
G (65.3)b
G (65.3)b
G (65.3)b
G (65.3)b
G (60.0)
G (60.0)
G (60.0)
G (60.0)
G (60.0)
S
G (32.0)
G (24.0)b
G (24.0)b
G (24.0)b
G (21.2)b
G(63.0)
n-heptane
n-octane
P
P
P
I
G(63.0)
G (39.3)
G(63.0)
n-decane
G (39.3)
G(63.0)
dodecane
toluene
PG
G (37.7)b
G (14.3)b
G(63.0)
S
S
S
S
S
S
S
S
I
S
S
P
P
S
P
I
xylenes
S
S
S
S
ethyl acetate
tetrahydrofuran
dioxane
S
S
G (24.0)
S
P
S
S
S
S
S
G (60.0)
P
S
acetone
S
P
G (40.8)
G (40.8)
I
n-propanol
2-propanol
G (29.5)
G (8.4)
G (60.0)
I
G (19.7)
G (25.8)
P
I
I
a Legend: G, opaque stable gel; PG, partial gel; S, soluble; I, insoluble; P, precipitation. Values in parentheses are the critical gelator concentrations
(CGCs) in mg/mL. All gels are light yellow unless otherwise noted. b The gel is transparent or translucent. c The gel is white.
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comparison to the corresponding emission band in the dilute
solution, the emission bands of 1aÀc in the gel state were
observed at ca. 506À507 nm, blue-shifted about 6 nm. Addi-
tionally, the dominant emission bands in the gel state of 2aÀc
were almost identical with those in the dilute solution, which
might be caused by the efficiency of pentiptycene in prevent-
ing interchain aggregation being higher than that of triptycene.10
The photophysical data of 1aÀc and 2aÀc are summarized in
Table S1 (Supporting Information).
An investigation of concentration- and temperature-variation
spectra was carried out in both solution and gel state. No significant
changes were observed in variable-concentration absorption and
emission spectra of 1aÀc and 2aÀc (Figures S15 and S16,
Supporting Information). However, it was found that the orga-
nometallic gels 1aÀc showed temperature-dependent emission
properties (Figure S17, Supporting Information). For instance,
the spectra of gel 1a exhibited a small red shift upon increasing
the temperature from 298 to 338 K. Similar results were found in
the investigation of the temperature-dependent emission spectra
of 1b,c. In contrast, 2aÀc showed no significant shifts in the
temperature-variation emission spectra. This was conceivable
because the interchain aggregation effect became weak by
introducing the iptycene moiety into the skeletons. Moreover,
the crystal-packing patterns of the precursor 4 and 7 provide
further support for the obtained results.
Although several models have been developed to indicate the
transition from a simple organic molecule to a gel,3 it is still
challenging to illustrate the exact mechanisms of such processes.
On the basis of all the above experimental facts, a possible
procedure for the formation of obtained organometallic gels is
proposed. At the beginning, the primary ordered strands are
formed from simple building blocks mostly driven by solvopho-
bic interactions and other weaker bonds such as van der Waals
interactions. Subsequently, these strands evolve to be secondary
structures of fibrils or bunches of fibrils (fibers). Finally, the
three-dimensional network is obtained from the mutual entan-
glement of linear fibers or the cross-linking of branching fibers. It
is noted that the spectroscopic investigations did not provide
obvious proof for the existence of PtÀPt interactions in the
aggregate structures in this study. In previous reports on supra-
molecular assemblies consisting of platinum terpyridine chro-
mophores, it has been well illustrated that the PtÀPt interactions
play an important role in the formation of supramolecular
aggregates.4a,6j The lack of significant PtÀPt interactions in our
systems might be caused by the fact that the platinum centers are
sterically congested by iptycene units.
Conclusion. In summary, we have successfully synthesized a
new series of platinum(II) acetylide complexes 1aÀc and 2aÀc
containing iptycene as cores. The structures of all compounds
were characterized by multinuclear NMR (1H, 31P, and 13C) and
mass spectroscopy and elemental analysis. Unexpectedly, all
compounds give rise to gels in some common organic solvents,
which provides a simple yet highly efficient approach to the
preparation of iptycene-containeing soft materials from medium-
sized building blocks. It was found that the compounds contain-
ing the triptycene moiety can form gels more easily than those
containing a pentiptycene subunit. By a change in the polarity of
the solvents, the morphology of the resulting organogels of 1c
could be tuned. This is the first report on the synthesis and study
of the properties of organometallic gels containing an iptycene
building block, which obviously enriches the library of organome-
tallic gels. Continued research to better understand the properties
and utilization of this new family of organometallic gels is being
carried out.
’ EXPERIMENTAL SECTION
1. General Experimental Procedures. Triptycene diacety-
lene and penptycene diacetylene were synthesized according to
the literature procedures.10 Tetrahydrofuran (THF) was distilled
from sodium/benzophenone. Diethylamine (Et2NH) was dried
from potassium hydroxide. Both of THF and Et2NH were degassed
by nitrogen (N2) for 30 minutes before use. All reactions were
performed in standard glassware under an inert N2 atmosphere.
1H NMR, 13C NMR, and 31P NMR spectra were recorded on
Bruker 300 MHz spectrometer (1H: 300 MHz; 13C: 75 MHz;
31P: 121.4 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 of 85%
H3PO4 (δ 0.0). Coupling constants (J) are denoted in Hz and
chemical shifts (δ) in ppm. Multiplicities are denoted as follows:
s = singlet, d = doublet, m = multiplet, t = triplet.
UV-Vis spectra were recorded with a Cary 50Bio UV-vis
spectrophotometer. Emission spectra were measured on a Cary
eclipse luminescence spectrometer. Samples for absorption and
emission measurements were contained in 1 cm or 0.2 cm quartz
cuvettes. SEM images of xerogels were obtained by using a
S-4800 (Hitachi Ltd.) with an accelerating voltage of 1.0 kV.
Samples were prepared by dropping dilute gels onto a silicon wafer.
2. Synthetic procedures. Synthesis of 4. To a solution of CuI
(24.6 mg, 0.129 mmol) and Pt(PEt3)2I2 (2.53 g, 3.687 mmol) in
a mixed solvent of 113 mL THF and 44 mL Et2NH was added
dropwise a solution of compound 3 (278.7 mg, 0.922 mmol) in
THF (30 mL) under an atmosphere of nitrogen. The mixture
was then stirred at room temperature for 3 hours. The solvent
was removed in vacuo and the residue was purified via column
chromatography with dichloromethane as eluent afforded the light
yellow solid of 4 with a yield of 54.3%: Rf = 0.47 (dichloromethane/
petroleum ether 3:2). Mp: 256 °C. lH NMR (CDCl3, 300 MHz):
δ 7.30 (dd, J = 3.3 and 5.4 Hz, 4H), 6.98 (dd, J = 3.3 and 5.4 Hz,
4H), 6.84 (s, 2H), 5.98 (s, 2H), 2.31-2.21 (m, 24H), 1.28-1.17 (m,
36H). 13C NMR (CDCl3, 75 MHz): δ 145.56, 144.47, 127.04,
124.89, 123.39, 120.86, 98.25, 93.18, 51.97, 16.53, 8.32.31P NMR
(CDCl3, 121.4 Hz): δ 9.42 (s, 1JPt-P = 2323.6 Hz).
Synthesis of 1a-c. Under an atmosphere of nitrogen, a mixed
solvent of 7.0 mL THF and 7.0 mL Et2NH was added to a mix-
ture of compound 4 (180 mg, 0.127 mmol), compound 5a
(204.6 mg, 0.508 mmol), and CuI (3.9 mg, 0.018 mmol). The
mixture was stirred at room temperature for 2 hours. The solvent
was removed in vacuo and the residue was purified via column
chromatography with dichloromethane as eluent afforded the
light yellow solid of 1a. The similar procedure was employed for
the preparation of compounds 1b and 1c.
Compound 1a. Yield, 75.1%, Rf = 0.50 (acetone/petroleum
ether 1:5). Mp: 106 °C. 1H NMR (CDCl3, 300 MHz ): δ 7.30
(dd, J = 3.3 and 5.4 Hz, 4H), 6.97-6.94 (m, 4H), 6.82 (s, 2H), 6.52
(s, 4H), 6.01 (s, 2H), 3.98-3.90 (m, 12H), 2.25-2.18 (m, 24H),
1.81-1.71 (m, 12H), 1.47-1.25 (m, 72H), 0.91 (t, J = 6.6 Hz,
18H). 13C NMR (CDCl3, 75 MHz): δ 152.57, 145.76, 144.38,
137.11, 127.18, 124.73, 123.36, 120.98, 110.54, 109.77, 107.22,
105.59, 73.33, 68.99, 52.02, 31.67, 31.48, 30.16, 29.29, 25.67, 22.57,
22.52, 16.42, 13.97, 13.92, 8.40. 31P NMR (CDCl3, 121.4 Hz): δ
1
12.10 (s, JPt-P = 2367 .4 Hz). Anal. Calcd for C100H154O6P4Pt2
CH2Cl2: C, 59.14; H, 7.67. Found: C, 59.31; H, 7.68. MALDI
3
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HRMS: m/z calced for C100H155O6P4Pt2, ([M + H]+) 1966.00,
found 1966.0.
Compound 2b. Yield, 74.2%: Rf = 0.60 (dichloromethane /
petroleum ether 6:1). Mp: 188 °C. 1H NMR (CDCl3, 300 MHz ):
δ 7.23 (dd, J = 3.3 and 5.1 Hz, 8H), 6.90-6.88 (m, 8H), 6.57 (s,
4H), 5.93 (s, 4H), 4.00-3.92 (m, 12H), 2.27-2.23 (m, 24H), 1.83-
1.73 (m, 12H), 1.41-1.27 (m, 144H), 0.87 (t, J = 6.6 Hz, 18H).
13C NMR (CDCl3, 75 MHz): 8 152.60, 146.24, 141.25, 136.94,
124.59, 123.61, 123.23, 117.17, 113.68, 109.77, 105.58, 104.49,
73.42, 68.99, 52.15, 31.91, 30.30, 29.73, 29.65, 29.42, 29.36,
26.12, 22.67, 16.44, 14.11, 8.62. 31P NMR (CDCl3, 121.4 Hz):
δ 12.23 (s, 1JPt-P = 2372.2 Hz). MALDI HRMS: m/z calced for
C150H235O6P4Pt2, ([M + H]+) 2646.63, found 2646.9.
Compound 2c. Yield, 97.3%: Rf = 0.60 (dichloromethane /
petroleum ether 4:1). Mp: 140 °C. 1H NMR (CDCl3, 300 MHz ): δ
7.22 (dd, J = 3.0 and 4.8 Hz, 8H), 6.90-6.87 (m, 8H), 6.57 (s,
4H), 5.93 (s, 4H), 4.00-3.91 (m, 12H), 2.27-2.23 (m, 24H), 1.83-
1.72 (m, 12H), 1.48-1.26 (m, 216H), 0.88 (t, J = 4.5 Hz, 18H).
13C NMR (CDCl3, 75 MHz): 8 152.63, 146.27, 141.29, 136.98,
124.62, 123.64, 123.26, 117.20, 113.72, 109.82, 105.62, 104.52,
73.47, 69.05, 52.18, 31.92, 29.73, 29.47, 29.37, 26.16, 22.69,
16.47, 14.13, 8.66. 31P NMR (CDCl3, 121.4 Hz): δ 12.26 (s,
1JPt-P = 2372.2 Hz). Anal. Calcd for C186H306O6P4Pt2: C, 70.86; H,
9.78. Found: C, 70.56; H, 10.17. MALDI HRMS: m/z calced for
C186H307O6P4Pt2, ([M + H]+) 3151.19, found 3151.4.
Compound 1b. Yield, 83%; Rf = 0.58 (acetone/petroleum
ether 1:7). Mp: 78 °C. 1H NMR (CDCl3, 300 MHz ): δ 7.30 (dd,
J = 3.3 and 5.4 Hz, 4H), 6.97-6.94 (m, 4H), 6.82 (s, 2H), 6.52 (s,
4H), 6.01 (s, 2H), 3.97-3.89 (m, 12H), 2.25-2.20 (m, 24H), 1.83-
1.67 (m, 12H), 1.46-1.22 (m, 144H), 0.88 (t, J = 6.9 Hz, 18H).
13C NMR (CDCl3, 75 MHz): δ 152.54, 145.83, 144.31, 136.91,
127.16, 124.70, 123.56, 123.36, 120.99, 110.97, 109.69, 107.20,
105.53, 73.34, 68.92, 52.02, 31.85, 30.24, 29.67, 29.65, 29.62,
29.59, 29.36, 29.31, 29.30, 26.06, 22.61, 16.35, 14.03, 8.39. 31P
NMR (CDCl3, 121.4 Hz): δ 11.87 (s, 1JPt-P = 2379.4 Hz). Anal.
Calcd for C136H226O6P4Pt2: C, 66.10; H, 9.22. Found: C, 65.68;
H, 9.63. MALDI HRMS: m/z calced for C136H227O6P4Pt2,
([M + H]+) 2470.56, found 2470.7.
Compound 1c. Yield, 78.8%; Rf = 0.60 (acetone/petroleum
ether 1:12). Mp: 67 °C. 1H NMR (CDCl3, 300 MHz ): δ 7.29-
7.28 (m, 4H), 6.97-6.96 (m, 4H), 6.82 (s, 2H), 6.52 (s, 4H), 6.01
(s, 2H), 3.98-3.90 (m, 12H), 2.25-2.20 (m, 24H), 1.81-1.71 (m,
12H), 1.46-1.23 (m, 216H), 0.88 (t, J = 6.9 Hz, 18H). 13C NMR
(CDCl3, 75 MHz): δ 152.61, 145.92, 144.35, 137.04, 127.22,
124.74. 123.63, 123.43, 121.07, 111.02, 109.85, 109.64, 107.27,
105.62, 73.42, 69.04, 52.10, 31.91, 30.31, 29.71, 29.66, 29.44,
29.35, 26.13, 22.67, 16.43, 14.08, 8.45.31P NMR (CDCl3, 121.4
Hz): δ 12.12 (s, 1JPt-P = 2377.0 Hz).
’ ASSOCIATED CONTENT
Synthesis of 7. To a solution of CuI (6 mg, 0.029 mmol) and
Pt(PEt3)2I2 (573 mg, 0.836 mmol) in 25 mL THF and 10 mL
Et2NH was added dropwise a solution of compound 6 (100 mg,
0.209 mmol) in THF (10 mL) under an atmosphere of nitrogen.
Then the mixture was stirred at room temperature for 1.5 hours.
The solvent was removed in vacuo and the residue was purified
via column chromatography with dichloromethane/petroleum
ether (1:1) as eluent afforded the light yellow solid of 7 with a
yield of 55.5%: Rf = 0.48 (dichloromethane /petroleum ether
S
Supporting Information. Figures and text giving details
b
of the syntheses and 1H, 31P, and 13C NMR spectra of 4, 1aÀc, 7,
and 2aÀc, high-resolution MALDI mass spectra of 1a,b and
2aÀc, electronic absorption spectra of 1aÀc and 2aÀc in dilute
solution and gel states, concentration-variation electronic ab-
sorption spectra, concentration-variation emission spectra, and
temperature-dependent emission spectra of gels. This material is
available free of charge via the Internet at http://pubs.acs.org.
l
1:1). Mp: >300 °C. H NMR (CDCl3, 300 MHz): δ 7.23 (dd,
’ AUTHOR INFORMATION
J = 3.3 and 5.4 Hz, 8H), 6.91 (dd, J = 3.3 and 5.4 Hz, 8H), 5.91 (s,
4H), 2.31-2.25 (m, 24H), 1.35-1.25 (m, 36H). 13C NMR (CDCl3,
75 MHz): δ 145.92, 141.53, 124.78, 123.24, 116.96, 95.86, 95.66,
52.09, 16.62, 8.69, 8.38. 31P NMR (CDCl3, 121.4 Hz): δ 9.59 (s,
1JPt-P = 2318.8 Hz).
Corresponding Author
*E-mail: hbyang@chem.ecnu.edu.cn.
’ ACKNOWLEDGMENT
Synthesis of 2a-c. Under an atmosphere of nitrogen, a mixed
solvent of 6.0 mL THF and 6.0 mL Et2NH was added to a
mixture of compound 7 (180 mg, 0.113 mmol), compound 5a
(181.9 mg, 0.452 mmol) and CuI (3.0 mg, 0.016 mmol). The
mixture was then stirred at room temperature for 2 hours. The
solvent was removed in vacuo and the residue was purified via
column chromatography with dichloromethane as eluent afforded
the light yellow solid of 2a. The similar procedure was employed
for the preparation of compounds 2b and 2c.
H.-B.Y. thanks the NSFC (Nos. 91027005 and 20902027),
Shanghai Pujiang Program (No. 09PJ1404100), Shanghai Shu-
guang Program (No. 09SG25), Innovation Program of the
SMEC (No. 10ZZ32), the RFDP (No. 20100076110004) of
Higher Education of China, and “the Fundamental Research
Funds for the Central Universities” for financial support. We
thank Prof. Jun-Li Hou (Fudan University) for help with SEM
measurements.
Compound 2a. Yield >99%: Rf = 0.40 (dichloromethane).
Mp: 266 °C dec. 1H NMR (CDCl3, 300 MHz ): δ 7.22 (dd, J =
3.3 and 5.1 Hz, 8H), 6.89 (dd, J = 3.3 and 5.4 Hz, 8H), 6.57 (s,
4H), 5.93 (s, 4H), 4.00-3.92 (m, 12H), 2.27-2.23 (m, 24H), 1.86-
’ REFERENCES
(1) Flory, P. J. Faraday Discuss. 1974, 57, 7.
(2) (a) Hoffmann, H. Adv. Colloid Interface Sci. 1990, 32, 123. (b) De
Gennes, P. G. Scaling Concepts in Polymer Physics; Cornell University
Press: Ithaca, NY, 1979. (c) Gelbart, W. M.; Ben-Shaul, A. J. Phys. Chem.
1996, 100, 13169.
(3) (a) Terech, P.; Weiss, R. G. Chem. Rev. 1997, 97, 3133–3159.
(b) Abdallah, D. J.; Weiss, R. G. Adv. Mater. 2000, 12, 1237–1247.
(c) Estroff, L. A.; Hamilton, A. D. Chem. Rev. 2004, 104, 1201–1217.
(d) vanEsch, J. H.; Feringa, B. L. Angew. Chem. Int. Ed. 2000, 39,
2263–2266. (e) Sangeetha, N. M.; Maitra, U. Chem. Soc. Rev. 2005,
34, 821–836. (f) Special issue: “Low Molecular Mass Gelators. Design,
1.70 (m, 12H), 1.49-1.30 (m, 72H), 0.92 (t, J = 6.9 Hz, 18H). 13
C
NMR (CDCl3, 75 MHz): δ 152.55, 146.19, 141.20, 136.94, 124.52,
123.59, 123.15, 117.09, 113.63, 109.78, 105.54, 104.43, 73.32,
68.93, 52.11, 31.69, 31.50, 30.17, 29.29, 25.69, 22.59, 22.54, 16.40,
14.00, 13.95, 8.54. 31P NMR (CDCl3, 121.4 Hz): δ 12.22 (s, 1JPt-P
=
2372.2 Hz). Anal. Calcd for C114H162O6P4Pt2: C, 63.91; H, 7.62.
Found: C, 63.77; H, 7.91. MALDI HRMS: m/z calced for
C
114H163O6P4Pt2, ([M + H]+) 2142.06, found 2142.1.
4037
dx.doi.org/10.1021/om2002987 |Organometallics 2011, 30, 4032–4038

Organometallics
ARTICLE
Self-Assembly, Function” (Fages F., Ed.): Top. Curr. Chem. 2005, 256.
(g) Molecular Gels: Materials with Self-Assembled Fibrillar Networks;
Weiss, R. G., Terech, P., Eds; Kluwer Academic: Dordrecht, The
Netherlands, 2005. (h) de Loos, M.; Feringa, B. L.; van Esch, J. H.
Eur. J. Org. Chem. 2005, 3615–3631.
Yang, H. -B.; Ghosh, K.; Zhao, L.; Stang, P. J. Chem. Eur. J. 2009,
15, 7203–7214. (g) Zhao, G.-Z.; Chen, L.-J.; Wang, C.-H.; Yang, H.-B.;
Ghosh, K.; Zheng, Y.-R.; Lyndon, M. M.; Muddiman, D. C.; Stang, P. J.
Organometallics 2010, 29, 6137–6140.
(9) Zhao, X.; Cardolaccia, T.; Farley, R. T.; Abboud, K. A.; Schanze,
(4) (a) Tam, A. Y.-Y.; Wong, K. M.-C.; Wang, N.; Zhu, G.; Yam,
V. W.-W. Langmuir 2009, 25, 8685–8695. (b) Cardolaccia, T.; Li, Y.;
Schanze, K. S. J. Am. Chem. Soc. 2008, 130, 2535–2545. (c) Diring, S.;
Camerel, F.; Donnio, B.; Dintzer, T.; Toffanin, S.; Capelli, R.; Muccini, M.;
Ziessel, R. J. Am. Chem. Soc. 2009, 131, 18177–18185. (d) Cai, W.; Wang,
G.-T.; Du, P.; Wang, R.-X.; Jiang, X.-K.; Li, Z.-T. J. Am. Chem. Soc. 2008,
130, 13450–13459. (e)Zhang, S.;Yang, S.; Lan, J.; Tang, Y.;Xue, Y.; You,J.
J. Am. Chem. Soc. 2009, 131, 1689–1691. (f) Zhan, C.; Gao, P.; Liu, M.
Chem. Commun. 2005, 462–464. (g) Wang, C.; Zhang, D.; Zhu, D.
Langmuir 2007, 23, 1478–1482. (h) Wang, S.; Shen, W.; Feng, Y.; Tian,
H. Chem. Commun. 2006, 1497–1499. (i) Yang, H.; Yi, T.; Zhou, Z.; Zhou,
Y.; Wu, J.; Xu, M.; Li, F.; Huang, C. Langmuir 2007, 23, 8224–8230.
(j) Wang, F.; Han, C.; He, C.; Zhou, Q.; Zhang, J.; Wang, C.; Ling, N.;
Huang, F. J. Am. Chem. Soc. 2008, 130, 11254–11255.
K. S. Inorg. Chem. 2005, 44, 2619–2627.
(10) Zhu, Z.; Swager, T. M. Org. Lett. 2001, 3, 3471–3474.
(5) (a) Ajayaghosh, A.; Varghese, R.; Praveen, V. K.; Mahesh, S.
Angew. Chem., Int. Ed. 2006, 45, 3261–3264. (b) Xu, Y.; Xue, P.; Xu, D.;
Zhang, X.; Liu, X.; Zhou, H.; Jia, J.; Yang, X.; Wang, F.; Lu, R. Org.
Biomol. Chem. 2010, 8, 4289–4296. (c) Ghosh, S.; Li, X.; Stepanenko, V.;
W€urthner, F. Chem. Eur. J. 2008, 14, 11343–11357. (d) Su, Y.-S.; Liu,
J.-W.; Jiang, Y.; Chen, C.-F. Chem. Eur. J. 2011, 17, 2435–2441.
(e) Dong, S.; Luo, Y.; Yan, X.; Zheng, B.; Ding, X.; Yu, Y.; Ma, Z.;
Zhao, Q.; Huang, F. Angew. Chem., Int. Ed. 2011, 50, 1905–1909.
(f) Duan, P.; Liu, M. Langmuir 2009, 25, 8706–8713. (g) Wang, C.;
Chen, Q.; Sun, F.; Zhang, D.; Zhang, G.; Huang, Y.; Zhao, R.; Zhu, D.
J. Am. Chem. Soc. 2010, 132, 3092–3096. (h) Zhu, L.; Ma, X.; Ji, F.;
Wang, Q.; Tian, H. Chem. Eur. J. 2007, 13, 9216–9222. (i) Wu, J.; Yi, T.;
Shu, T.; Yu, M.; Zhou, Z.; Xu, M.; Zhou, Y.; Zhang, H.; Han, J.; Li, F.;
Huang, C. Angew. Chem., Int. Ed. 2008, 47, 1063–1067.
(6) (a) Fages, F. Angew. Chem., Int. Ed. 2006, 45, 1680–1682.
(b) Kawano, S.; Fujita, N.; Shinkai, S. J. Am. Chem. Soc. 2004, 126, 8592–
8593. (c) Shirakawa, M.; Fujita, N.; Tani, T.; Kaneko, K.; Shinkai, S. Chem.
Commun. 2005, 4149–4151. (d) Camerel, F.; Bonardi, L.; Schmutz, M.;
Ziessel, R. J. Am. Chem. Soc. 2006, 128, 4548–4549. (e) Naota, T.; Koori,
H. J. Am. Chem. Soc. 2005, 127, 9324–9325. (f) Weng, W.; Beck, J. B.;
Jamieson, A. M.; Rowan, S. J. J. Am. Chem. Soc. 2006, 128, 11663–11672.
(g) Tu, T.; Aseenmacher, W.; Peterlik, H.; Weisbarth, R.; Nieger, M.;
D€otz, K. H. Angew. Chem., Int. Ed. 2007, 46, 6368–6371. (h) Piepenbrock,
M.-O. M.; Lloyd, G. O.; Clarke, N.; Steed, J. W. Chem. Rev. 2010,
110, 1960–2004. (i) Kishimura, A.; Yamashita, T.; Aida, T. J. Am. Chem.
Soc. 2005, 127, 179–183. (j) Tam, A. Y.-Y.; Wong, K. M.-C.; Wang, G. X.;
Yam, V. W.-W. Chem. Commun. 2007, 2028–2030.
(7) (a) Chong, J. H.; MacLachlan, M. J. Chem. Soc. Rev. 2009,
38, 3301–3315. (b) Yang, J.-S.; Swager, T. M. J. Am. Chem. Soc. 1998,
120, 11864–11873. (c) Yang, J.-S.; Yan, J.-L.; Hwang, C. -Y.; Chiou,
S.-Y.; Liau, K.-L.; Tsai, H.-H.; Lee, G. -H.; Peng, S.-M. J. Am. Chem. Soc.
2006, 128, 14109–14119. (d) Yang, J.-S.; Huang, Y.-T.; Ho, J.-T.; Sun,
W.-T.; Huang, H.-H.; Lin, Y.-C.; Huang, S.-J.; Huang, S.-L.; Lu, H.-F.;
Chao, I. Org. Lett. 2008, 10, 2279–2282. (e) Zhu, X.-Z.; Chen, C.-F.
J. Am. Chem. Soc. 2005, 127, 13158–13159. (f) Han, T.; Chen, C.-F. Org.
Lett. 2006, 8, 1069–1072. (g) Han, T.; Zong, Q.-S.; Chen, C.-F. J. Org.
Chem. 2007, 72, 3108–3111. (h) Chen, C.-F. Chem. Commun. 2011,
47, 1674–1688.
(8) (a) Yang, H.-B.; Das, N.; Huang, F.; Hawkridge, A. M.; Muddiman,
D. C.; Stang, P. J. J. Am. Chem. Soc. 2006, 128, 10014–10015. (b) Yang,
H.-B.; Hawkridge, A. M.; Huang, S. D.; Das, N.; Bunge, S. D.;
Muddiman, D. C.; Stang, P. J. J. Am. Chem. Soc. 2007, 129, 2120–
2129. (c) Yang, H.-B.; Ghosh, K.; Northrop, B. H.; Zheng, Y. -R.;
Lyndon, M. M.; Muddiman, D. C.; Stang, P. J. J. Am. Chem. Soc. 2007,
129, 14187–1489. (d) Ghosh, K.; Yang, H.-B.; Northrop, B. H.;
Lyndon, M. M.; Zheng, Y. -R.; Muddiman, D. C.; Stang, P. J. J. Am.
Chem. Soc. 2008, 130, 5320–5334. (e) Yang, H.-B.; Ghosh, K.; Zhao,
Y.; Northrop, B. H.; Lyndon, M. M.; Muddiman, D. C.; White, H. S.;
Stang, P. J. J. Am. Chem. Soc. 2008, 130, 839–841. (f) Zheng, Y. -R.;
4038
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