Design and preparation of platinum-acetylide organogelators containing ethynyl-pyrene moieties as the main skeleton

Article abstract of DOI:10.1002/chem.201202902

A series of new platinum-acetylide complexes containing ethynyl-pyrene moieties as the main skeleton were synthesized and characterized. The investigation of the absorption and emission spectra of these complexes revealed that the extension of the molecular size with the introduction of different numbered platinum-acetylide fragments can efficiently tune the absorption and emission bands from the UV to the longer wavelength region. Moreover, the gelation properties of these complexes were investigated by the "stable-to-inversion-of-a-test-tube" method. Most newly designed platinum-acetylide compounds presented a stable gel-formation property in some of the tested solvents. The morphology of the xerogels was investigated by scanning electron microscopy (SEM). Furthermore, the concentration- and temperature-dependent absorption and emission properties of these complexes were investigated, which support the formation of J-type assemblies during the aggregation process. More importantly, it was found that the complexes 4 a-C6, 4 a, and 4 a-C18 with four platinum-acetylide fragments presented potential applications as luminescent organometallic gels.

Full text of DOI:10.1002/chem.201202902

DOI: 10.1002/chem.201202902
Design and Preparation of Platinum–Acetylide Organogelators Containing
Ethynyl–Pyrene Moieties as the Main Skeleton
Xing-Dong Xu,[a] Jing Zhang,[a] Xudong Yu,[b] Li-Jun Chen,[a] De-Xian Wang,[c]
Tao Yi,*[b] Fuyou Li,[b] and Hai-Bo Yang*[a]
Abstract: A series of new platinum-
acetylide complexes containing ethyn-
yl-pyrene moieties as the main skeleton
were synthesized and characterized.
The investigation of the absorption and
emission spectra of these complexes re-
vealed that the extension of the molec-
ular size with the introduction of differ-
ent numbered platinum-acetylide frag-
ments can efficiently tune the absorp-
tion and emission bands from the UV
to the longer wavelength region. More-
over, the gelation properties of these
complexes were investigated by the
“stable-to-inversion-of-a-test-tube”
Furthermore, the concentration- and
temperature-dependent absorption and
emission properties of these complexes
were investigated, which support the
formation of J-type assemblies during
the aggregation process. More impor-
tantly, it was found that the complexes
4a-C6, 4a, and 4a-C18 with four plati-
num-acetylide fragments presented po-
tential applications as luminescent or-
ganometallic gels.
method. Most newly designed plati-
num-acetylide compounds presented a
stable gel-formation property in some
of the tested solvents. The morphology
of the xerogels was investigated by
scanning electron microscopy (SEM).
Keywords: gels
· luminescence ·
platinum · pyrene · self-assembly ·
supramolecular chemistry
Introduction
scale structures, which sequentially build up micrometer
scale interwoven three-dimensional networks, entrapping
solvent molecules. This process is spontaneous and easily
controlled without using advanced techniques. By a small
modification of the structure of the gelator subunit or by
changing the experimental conditions, such as the polarity
of solvents, the morphology and the properties of the result-
ed organogels could be finely tuned.[2a–c] Thus, this provides
a simple yet highly efficient approach to the preparation of
functional soft materials from small building blocks.
In particular, the self-assembly of organic p-conjugated
molecules into luminescent organogels has attracted much
attention because of their potential applications in field-
effect transistors (FETs), organic light-emitting diodes
(OLEDs), organic light-emitting transistors (OLETs), and
sensors.[2f,4,5] For example, Ajayaghosh and co-workers[5a]
has demonstrated that a oligo(p-phenylenevinylene) (OPV)-
based fluorescent organogelator exhibited superior detec-
tion capability for TNT in the gel form compared with that
in the solution state. Moreover, by introducing fluorescent
groups into gelators, several luminescent gels have been de-
signed and synthesized.[6] As a p-conjugated molecule,
pyrene and its derivatives[7] have been explored in the field
of luminescent gels.[8] For instance, Kato and co-workers[8a]
have reported color-tunable blue fluorescent organogels
containing pyrene moieties and dendritic oligopeptides.
However, despite their wide application in the area of mate-
rial science, there is one major drawback in using pyrene as
a chromophore; the absorption and emission wavelengths of
the pyrene monomer are generally confined to the UV
region. In fact, it is desirable to employ a fluorophore probe
Organogels, as an important class of soft material, have
evolved to be one of the most attractive subjects within su-
pramolecular chemistry and material sciences during the
past few decades.[1–3] During the process of gelation, self-as-
sembly has proven to play an essential role by employing in-
termolecular non-covalent interactions, such as hydrogen-
bonding, metal–ligand coordination, p–p interaction, elec-
trostatic and van der Waals forces, hydrophobic and hydro-
philic interactions.[2,3] Driven by such non-covalent interac-
tions, the organic gelators self-assemble to form nanometer
[a] X.-D. Xu, J. Zhang, L.-J. Chen, Prof. H.-B. Yang
Shanghai Key Laboratory of Green Chemistry
and Chemical Processes, Department of Chemistry
East China Normal University, 3663 N. Zhongshan Road
Shanghai 200062 (P.R. China)
Fax : (+86)21-6223-5137
E-mail: hbyang@chem.ecnu.edu.cn
[b] X. Yu, Prof. T. Yi, Prof. F. Li
Department of Chemistry, Fudan University
Shanghai 200433 (P.R. China)
Fax : (+86)21-5566-4185
E-mail: yitao@fudan.edu.cn
[c] Prof. D.-X. Wang
Beijing National Laboratory for Molecular Sciences
CAS Key Laboratory of Molecular Recognition
and Function Institute of Chemistry
Chinese Academy of Sciences
Beijing 100190 (P.R. China)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201202902.
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FULL PAPER
that absorbs and emits in the longer wavelength region,
preferably in the visible region when it is employed as a bio-
sensor.[9] It has been demonstrated that the emission charac-
teristics of pyrene derivatives can be bathochromatically
tuned to the visible region by extending the p-conjugated
systems upon the introduction of ethynyl subunits.[10a] Along
with this strategy, ethynyl-pyrene derivatives and oligomers
have been extensively explored in the area of photonic devi-
ces and biological probes.[10] However, little attention has
been paid to the preparation of luminescent organogels by
using p-conjugated ethynyl-pyrene moieties as the main
skeleton, which might be caused by the obstacle of synthe-
sis.[11]
and synthesis of new supramolecular gels consisting of
metal-organic skeletons. Particularly, the construction of
functionalized organometallic gels is of great interest. Based
on our previous research results on platinum-acetylide
chemistry,[14,15,18] we envisioned that the ethynyl-pyrene
moiety might serve as an ideal and unique platform for the
construction of new luminescent organometallic gels. Sur-
prisingly, to the best of our knowledge, there is no report on
the construction of platinum-acetylide organogels containing
ethynyl-pyrene moieties as main scaffold. Herein, we de-
signed and synthesized a family of new platinum-acetylide
gelators 1a–4a (Figure 1) employing the ethynyl-pyrene
In the past few decades, there has been growing interest
in the investigation of organometallic gels, because the pres-
ence of metal centers allows for the additional scope to tune
the gel properties such as photochemistry, electrochemistry,
and catalytic activity.[12] For example, Adia and co-work-
ers[12e] have successfully synthesized an interesting class of
trinuclear AuI pyrazolate metallacyclic gels. Upon doping or
de-doping of AgI ions, the gel–sol phase transition showed a
reversible switching of red-green-blue luminescence. Very
recently, Tu and co-workers has realized the visual chiral
recognition of (R)- and (S)-binap through an enantioselec-
tive breakdown of metallogels prepared from new aromatic-
linker-steroidal-type pincer platinum gelators.[12l]
Figure 1. Molecular structures of the target complexes 1a–4a and 1b–4b.
It should be noted that platinum-acetylide complexes
have been extensively explored in the area of supramolecu-
lar self-assembly[13,14] and functional material sciences[15,16]
due to their unique p-conjugated character. Recently, plati-
num-acetylide gelators have received considerable attention
because of their versatile spectroscopic and luminescence
properties.[17] For instance, the groups of Yam[17a] and Zies-
sel[17b] have prepared a series of new alkynylplatinum com-
pounds, respectively, which were capable of forming stable,
charged metallogels and showed rich luminescence proper-
ties. Different from the research objects of Yam and Ziessel,
Schanze, and co-workers[17c] reported the first example of
neutral platinum-acetylide organogelators and observed the
triplet exciton diffusion and trapping in a molecular aggre-
gation. Evidently, this is just a prelude of the investigation
of the neutral platinum-acetylide compounds as the new or-
ganometallic gelators. Recently, we have reported the con-
struction of a series of new platinum-acetylide gelators with
different cores.[18] For example, a new family of the rod-coil-
shaped platinum-acetylide complexes exhibited a highly or-
dered honeycomb pattern on a large-scale in their xero-
gels.[18a] Moreover, we have proven that, different from
other shapes such as linear or triangular, the rectangular
platinum-acetylide derivatives featured a stronger tendency
of gelation.[18b] Although a great number of platinum-acety-
lide gelators have been reported by the groups of Ziessel,
Yam, Schanze, and Sun and so on, there are few studies on
introducing the functional group to the platinum-acetylide
skeletons.
moiety as a key skeleton. To investigate the influence of the
amide on gel formation, another series of platinum-acetylide
complexes 1b–4b with an amide group were also designed
and synthesized. It was found that most of the newly de-
signed platinum-acetylide complexes presented a stable gel
formation property in the tested solvents. Extension of the
molecular size with the introduction of different numbered
conjugated platinum-acetylide fragments can efficiently tune
the absorption and emission properties from the UV to the
longer wavelength region. Particularly, it was found that the
new organometallic gelatos with four platinum-acetylide
fragments presented potential applications as luminescent
organometallic gels.
Results and Discussion
Synthesis and characterization: The preparation of plati-
num-acetylide complexes 1a–4a and 1b–4b is outlined in
Schemes 1–3, respectively. The synthesis began with the So-
nogashira coupling of the protected acetylene with different
bromopyrenes with various substitution patterns.[19] For ex-
ample, the cross-coupling of 1-bromopyrene (10) with (tri-
methylsilyl)acetylene (TMSA) in the presence of [Pd-
AHCTUNTGRENGUN(N PPh3)4] and CuI as the catalyst afforded the mono-(trime-
thylsilylethynyl) pyrene (11). Then, 1-alkynylpyrene (12)
was prepared by the deprotection reaction of 11 with K2CO3
in a mixture of methanol and THF. Compound 12 was then
reacted with trans-[PtI2ACHTNUTRGNE(UNG PEt3)2] (4 equiv) to give compound
Moreover, compared with the considerable work on su-
pramolecular organogels, there is a large space in the design
5 in accordance with the similar procedure in our previous
reports.[14,15,18] Subsequent coupling reaction with the corre-
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T. Yi, H.-B. Yang et al.
Figure 2. Theoretical (gray) and experimental (black) MALDI-TOF-MS
spectra of 4a.
successful. However, single crystals of the key precursors 5–
8 were grown by slow evaporation of a mixture solution of
dichloromethane and methanol at ambient temperature for
5–7 days. All the crystal structures of precursors 5–8 are
shown in Figure 3. Each ORTEP representation of the crys-
Scheme 1. Synthesis route of target molecules 1a and 1b.
sponding alkynes resulted in the final complexes in high
yield (1a, 92.4%; 1b, 97.0%). Similarly, the other platinum-
acetylide complexes 2a–4a and 2b–4b were synthesized by
employing the coupling reaction of trans-[PtI2ACTHNUTRGEN(UGN PEt3)2] with
À
C H bonds in alkynes as the key step, respectively
(Scheme 2 and Scheme 3).
The molecular structures of complexes 1a–4a and 1b–4b
were characterized by using multiple nuclear NMR spectros-
copies (1H, 31P, and 13C), mass spectroscopy, and elemental
analysis. The multinuclear NMR analyses of all target mole-
cules exhibited very similar characteristics, which all suggest-
ed the formation of discrete, highly symmetric platinum-ace-
tylide conjugates with ethynyl-pyrene moieties as cores. For
instance, the 31P {1H} NMR spectra of 1a and 1b displayed a
sharp singlet (ca. d=11.7 ppm) shifted downfield from the
starting platinum compound 5 by approximately d=2.8 ppm
due to the electron-withdrawing large p-conjugated bridges.
1
Figure 3. Crystal structures of precursors a) 5, b) 6, c) 7, and d) 8.
In addition, the H NMR spectra of all complexes showed
characteristic proton resonances of various substituted pyr-
enes. For example, in the spectrum of 4a, two singlets at d=
8.51 and 7.88 ppm in a 2:1 ratio for the typical protons on
pyrene ring were found. In particular, the MALDI-TOF-MS
spectrometric studies of complexes 1a–4a and 1b–4b pro-
vided further strong support for the formation of the desired
complexes (see the Supporting Information). For example,
the MALDI-TOF-MS spectrum of 4a exhibited a strong
signal of 4633.975, corresponding to the [M+H]+ species.
This peak was isotopically resolved, and it is in good agree-
ment with its theoretical distribution (Figure 2).
tal structure showed that all atoms (except for the triethyl-
phosphine ligands) lie approximately in the same plane. The
platinum atoms in the complexes were found to adopt a
slightly distorted trans square-planar geometry with C-Pt-P
and P-Pt-I angles in the ranges 84.7 and 95.58, which might
be caused by the steric demand of the bulky triethylphos-
phine ligands. Interestingly, the alkyne bond was shorter
ꢀ
than the typical C C bond in the compound end-capped
with an acetylenyl benzene group (e.g., the bond length is
1.20 ꢁ for 5).[20] This difference may be caused by the ethyn-
yl-pyrene group, which makes the alkyne bond more elec-
Unfortunately, all attempts to grow X-ray quality single-
crystals of the complexes 1a–4a and 1b–4b have proven un-
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Platinum-Acetylide Organogelators
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Scheme 2. Synthesis route of target molecules 2a, 2b, 3a, and 3b.
tron-rich. Table S2 in the Supporting Information summariz-
es the data, structure solution, and refinement for crystal
structures 5–8.
absorption bands are described as an admixture of intraACHTUNGTRENNUNGli-
ꢀ
E
G
ꢀ
fer (MLCT) [d(Pt) p–p*
G
The investigation of UV/Visible absorption spectroscopy
of the platinum-acetylide complexes 1a–4a and 1b–4b in di-
luted dichloromethane solutions were carried out at 298 K.
The electronic absorption spectra of complexes 1a–4a with-
out an amide group and complexes 1b–4b with an amide
group exhibited very similar patterns (Figure 4 and Fig-
ure S1 in Supporting Information). For example, the absorp-
tion spectrum of 1a showed intense absorption bands in the
range of 234–291 nm and 368–399 nm. Likewise, the absorp-
tion spectrum of 1b is dominated by strong absorption
bands at lmax =291 and 386 nm. With reference to the previ-
ous spectroscopic investigation[21] by Yam and Ziessel on
nant IL character. The higher-energy absorption bands are
likely due to p–p* and n–p* transitions localized on the al-
koxyphenyl fragments. It should be noted that the absorp-
tion maxima of the platinum-acetylide bridged pyrene deriv-
atives 1a–4a and 1b–4b consecutively shift to the longer
wavelength region, and their absorption coefficients increase
with the increase of the number of platinum-acetylide
groups (Table 1 and Table S1 in the Supporting Informa-
tion). For example, the absorption spectrum of 4a showed a
pronounced bathochromic shift of the main absorption
bands, which are now located in the range of 458 and
490 nm. This electronic absorption spectrum exhibited a dra-
matic redshift of ꢁ155 nm as compared with that of a naked
ꢀ
trans-[PtACHTUNGTRENNUNG(PEt3)2ACHTUNGTRENNUNG(C CR)2] and its derivatives, the low energy
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T. Yi, H.-B. Yang et al.
Scheme 3. Synthesis route of target molecules 4a and 4b.
pyrene[22] (335 nm), which is attributed to the introduction
of multiple conjugated ethynyl-phenyl fragments.
ed by the “stable-to-inversion-of-a-test-tube” method in var-
ious polar or nonpolar, aromatic or nonaromatic solvents. It
was found that most compounds exhibited stable gel-forma-
tion properties in nonpolar alkyl solvents or polar alcohol
solvents such as cyclohexane, n-hexane, n-propanol, and so
on. In each case, the complete volume of solvent is immobi-
lized and can support its own weight without collapsing. The
photographs of selected organometallic gels of 1b and 2b
are shown in Figure 5 as representatives.
The obtained organometallic gels exhibited thermally re-
versible sol-to-gel phase transitions. Moreover, it was found
that the structural effects, such as the number of platinum-
acetylide fragments and the existence of the amide group,
have an observable influence on the gel formation. For in-
stance, complex 1a was found to be deprived of gelation
ability, and upon cooling to the room temperature, partial
gels were always found in the tested solvent. However, com-
plex 1b with amide group can form gels in the most nonpo-
lar alkyl solvents, even in some polar alcohol solvents.
Moreover, compared with the complex 1a without an amide
group, complex 1b has a lower critical gelator concentration
(CGCs) when forming gels. For instance, the CGC of 1b in
n-propanol was 28.6 mgmLÀ1, indicating that one molecule
of 1b could entrap approximately 665 solvent molecules,
whereas the CGC of 1a in n-propanol was 52.0 mgmLÀ1.
We envisioned that the presence of amide groups may lead
to stronger intermolecular interactions through the forma-
tion of hydrogen bonds, resulting in a higher tendency
toward the gelation. Similar investigation results were ob-
served in the case of 2a and 2b. Unexpectedly, in the case
of 3b and 4b, no gel was obtained because they were insolu-
The emission spectroscopy of the platinum-acetylide com-
plexes 1a–4a and 1b–4b in diluted dichloromethane solu-
tions were also investigated (Figure 4b and Figure S1 in the
Supporting Information). It was found that the emission
spectra of complexes from 1a to 4a presented a redshift
from 435 to 537 nm with the introduction of different num-
bers of platinum-acetylide fragments, which is indicative of
an efficient delocalization in the excited state. Introduction
of one platinum-acetylide fragment to the pyrene unit led to
a bathochromic shift of ꢁ42 nm as compared with a naked
pyrene[22] (393 nm), and introduction of four platinum-acety-
lide fragments resulted in a dramatic bathochromic shift of
almost 144 nm. For example, under excitation at the low-
energy absorption band (lex =365 nm) in diluted dichloro-
methane solution, compound 4a showed intense emissions
at approximately 506 and 537 nm with a quantum yield of
35%. Evidently, the extension of the molecular size with the
introduction of conjugated platinum-acetylide fragments can
efficiently tune the emission properties from the UV to the
longer-wavelength region. Moreover, in the emission spec-
trum of each complex, the mirror symmetry with the respect
to the lowest-energy absorption bands was observed, which
indicated the same optical transition involving in both ab-
sorption and emission processes. The related photophysical
data for 1a–4a and 1b–4b was summarized in Table 1 and
Table S1 in the Supporting Information.
Gelation properties: The gelation properties of the plati-
num-acetylide complexes 1a–4a and 1b–4b were investigat-
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Platinum-Acetylide Organogelators
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Figure 5. The gel state photographs of a) 1b in various organic solvents
(from left to right): cyclohexane, n-hexane, n-heptane, n-octane, n-
decane, n-propanol, and isopropanol; and b) 2b in various organic sol-
vents (from left to right): cyclohexane, n-hexane, n-heptane, n-octane,
and n-decane.
during the process of molecular aggregation. The more
amide groups might lead to the existence of increased hy-
drogen-bonding, thus resulting in the precipitation of com-
plexes 3b and 4b in the test solvents. It should be noted
that compared with the typical low-molecular-weight orga-
nogelator molecules, the organometallic gelators in this
study have relatively higher CGCs when they formed gels.
However, considering the large molecular weight of these
compounds, for example, 4636.19 Da for 4a, the CGCs are
still acceptable. Interestingly, in contrast to other complexes,
which formed the turbid gels in the most tested solvents,
transparent gels were obtained in the case of 2b in nonpolar
alkyl solvents. The gelation properties of all compounds 1a–
4a and 1b–4b are summarized in Table 2.
Figure 4. a) UV/Vis absorption and b) emission spectra of 1a–4a in
CH2Cl2 in 1.0ꢂ10À5 m at room temperature (lex =365 nm).
To investigate the morphologies of the obtained metallic
organogels, scanning electron microscopy (SEM) was per-
formed with the corresponding xerogels (air-dried gels). Gel
samples were slowly evaporated to dryness, and the resul-
tant xerogels were examined. It was found that the morphol-
ogies of xerogels were dependent on the molecular shapes
and the solvents of gelation, as shown in Figure 6 and the
Supporting Information. Moreover, fibrous networks were
observed in many cases, which is similar with the typical or-
ganogels and metallogels. For example, the SEM micrograph
of 3a in n-propanol and isopropanol showed large multi-lay-
ered fibers, which are relatively straight with only slight
bending. The smallest fibers present have an approximate
width of 200 nm (Figure 6e and f). A lack of twisting and
regular shape indicates that the fibers are formed by well-or-
dered molecular packing. Furthermore, the SEM micro-
graph of 1b in cyclohexane exhibited a thick, dense, fibrous
network (Figure 6a). Different from 3a, which showed elon-
gated fibers as mentioned above, the fibers in 1b are fused
together to form thick clumps of fibers resulting in a dense
irregular network. The fibers are approximately 100 nm in
width and fuse together to form bundles that are approxi-
mately 15 mm in width. This result indicates that when the
solvent-gelator interactions become too strong, isotropic ge-
Table 1. Photophysical properties of compounds 1a–4a at 298 K in
CH2Cl2 (1.0ꢂ10À5 m).
Compound
labs [nm]
e [mÀ1 cmÀ1
]
lF [nm]
Fem [%]
1a
399
387
368
291
234
434
404
301
288
238
434
407
338
234
490
458
368
232
41900
44400
36800
43200
58100
105800
68200
59100
58900
87600
69700
47500
49500
76100
90300
56200
83000
108000
435
0.61
2a
458
453
0.83
3a
4a
0.29
506
537
35.32
ble in the most of the tested solvents. This result indicates
that there is a balance between gelation and precipitation
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T. Yi, H.-B. Yang et al.
Table 2. Solvents tested for gelation with compounds 1a–4b.[a]
greater depth/volume. The regular shape and the
extreme ratio between width and length in this
system may arise from a strong anisotropic growth
process resulting in the possible presence of some
1-D structure in the system. It should be noted, the
morphologies of the xerogels were strongly influ-
enced by the polarity of tested solvents as well. For
example, in the case of 1b, a dense network of con-
tinuous fibrous structures was observed in cyclo-
hexane, whereas the gel featured a sheet-like mor-
phology in n-propanol (Figure 6d).
Solvent
1a
1b
2a
2b
3a
3b 4a
4b
cyclohexane
n-hexane
n-heptane
n-octane
n-decane
dodecane
benzene
S
I
G
G
G
G
G
G
S
S
S
G
G
S
N
G
I
I
P
P
G
S
S
PG
I
I
I
S
(96.0)
G
G
G
G
G
G
S
S
S
S
S
S
S
S
S
G
G
PG
S
P
I
I
I
I
S
S
S
G
G
G
S
S
S
I
I
I
I
I
I
I
P
S
P
I
PG
PG
PG
PG
S
S
S
G
T
U
I
R
S
S
S
PG
PG
P
S
S
P
I
toluene
xylenes
n-propanol
isopropanol
acetone
tetrahydrofuran
ethyl acetate
E
ACHTUNGTRENNUNG
A
I
I
I
G
S
P
(26.0)
P
S
P
I
S
I
P
S
P
S
S
S
P
Study of the aggregation process in solution: To
obtain insights into the aggregation mode during
the gel formation, a further spectroscopic investi-
gation of these platinum-acetylide gelators was car-
ried out. Complex 2b was selected as a representa-
tive to illustrate the spectroscopic changes during
the gel formation. Firstly, the UV/Visible absorp-
P
S
[a] G=opaque stable gel; S=soluble; I=insoluble; P=precipitation. The values in
parentheses are the critical gelation concentrations (CGCs) in mgmLÀ1. [b] The gel is
transparent.
tion spectra of 2b in cyclohexane at different concentration
were measured. As shown in Figure 7a, it was found that
Figure 6. SEM images of the xerogels of 1b in a) cyclohexane, b) n-hep-
tane, c) n-octane, d) n-propanol and 3a in e) n-propanol, f) isopropanol.
Scale bars: 20.0 mm.
lator molecular aggregation occurs resulting in the loss of
the fibrous structure and favoring of clusters, which has
been reported in the previous report.[23] Interestingly, when
the solvents changed from cyclohexane to n-heptane or n-
octane, the rope-like fibers were obtained as shown in Fig-
ure 6b and c. The fibrous network is made up of fibers that
are approximately 170 nm in width and orientated randomly
relative to each other. The thin fibers twist together in bun-
dles to produce rope-like thicker fibers with a width of
1.3 mm, and are hardly distinguished from the thinner fibers
because their highly twisted nature results in a relatively
Figure 7. UV/Vis absorption spectra of 2b in cyclohexane a) at different
concentrations and b) different temperatures (1.0ꢂ10À4 m).
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Platinum-Acetylide Organogelators
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the increase of the concentration from 1.0ꢂ10À6 to 5.0ꢂ
10À5 m at 298 K, led to a decrease in the intensity of the ini-
tial absorption bands at 366 and 386 nm with the concomi-
tant growth of an intense redshifted band at 427 nm through
an isosbestic point at 392 nm. This observation is consistent
with the formation of J-type assemblies during the aggrega-
tion process as illustrated in previous reports,[24] which was
promoted by the hydrogen-bonding and hydrophobic inter-
actions between the complex molecules. Additionally, as
shown in Figure 7b, upon warming a gelled solution of 2b
(1.0ꢂ10À4 m in cyclohexane), the absorption spectrum of gel
2b exhibited a small blueshift upon increasing the tempera-
ture from 288 to 338 K.
Over the same temperature range the sample undergoes a
gel–sol transition. Thus, the thermally induced shift in the
emission spectra is clearly associated with the phase transi-
tion.
1
Furthermore, the concentration-dependent H NMR spec-
troscopic studies of 1b–4b in CDCl3 were performed to
probe the driving forces for the self-assembly process
(Figure 9 and Figure S6–S8 in Supporting Information). It
It should be noted that the complex 2b also showed con-
centration- and temperature-dependent emission properties
(Figure 8a and b). For example, upon increasing the concen-
tration from 1.0ꢂ10À6 to 1.0ꢂ10À3 m at 298 K, the high-
energy emission band at 493 nm was observed to disappear
with a concomitant growth of a new low-energy emission at
approximately 544 nm. Moreover, as shown in Figure 8b,
the emission spectrum of 2b featured a slight blueshift (ca.
12 nm) by warming a gelled solution from 288 to 338 K.
Figure 9. Region of the 1H NMR spectrum (400 MHz, CDCl3, 298 K) of
compound 2b at different concentrations.
was found that the NH resonance displayed an obvious
downfield shift upon an increase of concentration (e.g., 2b,
d=7.631 ppm at 1.6 mm and d=7.889 ppm at 50 mm), which
was indicative of the existence of hydrogen-bonding interac-
tions during the formation of supramolecular aggregates in
the case of 1b–4b.
Based on all above experimental facts, a possible mecha-
nism for the formation of such organometallic gels was pro-
posed. Initially, the primary-ordered aggregates were
formed from the simple building blocks mostly driven by hy-
drophilic/hydrophobic interaction, hydrogen-bonding (for
1b and 2b), and other possible non-covalent interactions.
Subsequently, these primary aggregates evolved to be secon-
dary fiber-like structures, which ultimately intertwine to
form large intense three-dimensional networks or other
morphologies with large bulks. Although it is still very diffi-
cult to demonstrate the definite process of the formation of
such organometallic gels, there is no doubt that the structur-
al effects, such as the number of platinum-acetylide frag-
ments and the existence of the amide group, play important
roles during the formation of ordered aggregates.
Investigation of luminescent organometallic gels: As men-
tioned previously, the luminescent organogels containing p-
Figure 8. Emission spectra of 2b in cyclohexane a) at different concentra-
tions and b) different temperatures (CGC concentration).
Chem. Eur. J. 2012, 18, 16000 – 16013
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T. Yi, H.-B. Yang et al.
conjugated
chromophores
have received considerable at-
tention because of their poten-
tial applications in the area of
optical and semiconductor ma-
terials.[2f,4,5] Inspired by the
fact that the complex 4a with
four platinum-acetylide frag-
ments featured the intense
emissions in the longer-wave-
length region with a quantum
yield of 35%, the further in-
vestigation on this new family
organometallic gels was car-
ried out.
Scheme 4. Synthesis route of complexes 4a-C6 and 4a-C18.
To check the effect of the
length of the alkoxy chains
during the formation of supermolecular aggregation, the
synthesis of other compounds (4a-C6 and 4a-C18) with dif-
ferently sized alkoxy chains was carried out (Scheme 4).
Their molecular structures and purity were characterized by
using multiple nuclear NMR spectroscopies (1H, 31P, and
13C), mass spectroscopy, and elemental analysis (see the
Supporting Information).
In the gel states of 4a-C6, 4a, and 4a-C18, the absorption
spectra displayed a small redshift by about 10 nm compared
with that in diluted solutions (Figure 10a). This change is
very similar to the spectra of J-aggregates of p-conjugated
chromophores with a slipped stacked geometry.[26] Notably,
all the platinum-acetylide complexes 4a-C6, 4a, and 4a-C18
presented strong emissive properties in the gel states at
298 K (Figure 10 insert). Compared with the emission spec-
tra of 4a-C6 in dilute solution, the decrease of emission
bands at approximately 506–507 nm along with the increase
of emission bands at approximately 535–538 nm was found
in their gel states. Moreover, in the case of 4a-C6, the emis-
sion maxima featured a large redshift from that measured in
dilute solution by approximately 70 nm. This change, as well
as the broad and featureless emission, is probably caused by
the formation of excimers in the solid states.
The excitation spectra of 4a-C6 with different concentra-
tions have been monitored to provide further support for
the formation of excimers in gel states. The peak maximum
showed a redshift of 18 nm with the emission at 535 nm
from 8.0ꢂ10À6 to 8.0ꢂ10À5 m at 298 K (Figure S5 in the Sup-
porting Information). In addition, the time-resolved fluores-
cence measurement of 4a-C6 both in the gel state and in
solution was carried out. It was found that the fluorescence
lifetimes of 4a-C6 in gel state are 0.34 and 1.01 ns, whereas
those in the sol state are 1.01 and 4.08 ns, respectively.
These results indicated the formation of the excimer of the
ethynyl-pyrene derivative in the gel state, which is consistent
with the similar report by Kato and co-workers.[27] Interest-
ingly, 4a-C6 showed concentration- and temperature-de-
pendent emission properties (Figure 10b and the Supporting
Information). For example, in the case of 4a-C6, upon an in-
crease in the concentration from 8.0ꢂ10À6 to 4.0ꢂ10À4 m at
Figure 10. a) Normalized UV/Vis spectra of 4a-C6 in solution (8.0ꢂ
10À6 m) and in gel state (4.0ꢂ10À3 m) in cyclohexane; b) emission spectra
of 4a-C6 in cyclohexane at different concentrations (lex =365 nm). The
insets show the photographs of 4a-C6 in solution (8.0ꢂ10À6 m) and gel
state in cyclohexane under a) visible and b) UV light, respectively.
298 K, the high-energy emission band at 493 nm was ob-
served to disappear with a concomitant growth of a new
low-energy emission at approximately 544 nm (Figure 10b).
Similar results were found in the case of 4a and 4a-C18 (see
the Supporting Information).
Interestingly, the morphologies of the gel structures re-
sulting from complexes 4a-C6, 4a and 4a-C18 featured dif-
16008
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Platinum-Acetylide Organogelators
FULL PAPER
Figure 11. SEM images of the xerogels of a) 4a-C6 in cyclohexane, b) 4a
in n-octance, and c) 4a-C18 in n-heptane. Scale bars: 5.0 mm.
ferent characteristics (Figure 11). For instance, in the case of
4a-C6, short sticks were obtained in the SEM images, which
is obviously different from the typical organogels with fi-
brous networks. The diameter observed for the sticks is in
the range of 400–900 nm, and their length is approximately
40 mm. For the xerogel from compound 4a in n-octane, it ap-
peared as a 3D network comprised of entangled fibers with
diameter of 400–600 nm. Moreover, compound 4a-C18 in n-
heptane exhibited a cross-linked globular morphology with
a dense network of fibrillar structures inside. Given the sim-
ilar polarity of the three types of solvent, the different mor-
phology of xerogels derived from 4a-C6, 4a, and 4a-C18
might be caused by the effect of the length of the alkoxy
chains.
With the aim of obtaining further insight into the mor-
phologies and optical properties of this new family of orga-
nometallic gels, the laser scanning confocal microscopy
(LSCM) was performed[28] on the xerogels of 4a-C6, 4a, and
4a-C18 (Figure 12). Notably, the green luminescence is emit-
ted from a nanoscale structures, which is directly observed
by LSCM images as shown in Figure 12. Moreover, the in-
vestigation of LSCM on samples of 4a-C6, 4a and 4a-C18
offered similar morphologies as that observed in the SEM
studies. The short sticks, 3-D networks comprised by fibers,
and porous globular structures were found in LSCM images
of 4a-C6, 4a, and 4a-C18, respectively, which again proved
the effect of the length of the alkoxy chains on the morphol-
ogies of the metallic organogels.
Figure 12. LCSM images of xerogels of compound a) 4a-C6 in cyclohex-
ane, b) 4a in n-octane, and c) 4a-C18 in n-heptane (lex =405 nm, emis-
sion was collected at 450–550 nm).
using multiple nuclear NMR spectroscopies (1H, 31P, and
13C), mass spectroscopy, and elemental analysis. It was
found that the absorption and emission maxima of these
platinum-acetylide complexes consecutively shift to longer-
wavelength regions and their absorption coefficients in-
crease with increasing number of platinum-acetylide groups.
Moreover, most of these complexes featured stable gel-for-
mation properties in the tested solvents. The supramolecular
molecular aggregation in solution was studied through con-
centration- and temperature-dependent absorption and
emission spectra. Furthermore, the concentration-dependent
1H NMR spectroscopic studies were performed as well. All
the results indicated that the hydrophobic interaction be-
tween alkyl chains and the hydrogen-bonding between
amides play important roles during the formation of ordered
aggregates. More importantly, it was found that the gelated
materials 4a-C6, 4a, and 4a-C18 with four platinum-acety-
lide fragments exhibited strong luminescence.
In summary, we have designed and synthesized a series of
new platinum-acetylide complexes containing ethynyl-
pyrene moieties as the main skeleton, which enrich the
family of platinum-acetylide complexes. Moreover, with
proper design and modification, these platinum-acetylide
compounds can tune their luminescence from blue to
yellow. This result indicated that these newly designed com-
plexes have promising potential as flexible full-color organic
light-emitting diode displays or other luminescent materials.
More importantly, it was found that most of these com-
plexes featured stable gel-formation properties. Particularly,
complexes 4a-C6, 4a, and 4a-C18 with four platinum-acety-
lide fragments presented potential applications as lumines-
Conclusion
We utilized the coupling reaction of trans-[PtI2ACTHNUTRGEN(UGN PEt3)2] with
À
C H bonds in alkynes as a key step to synthesize a series of
neutral platinum-acetylide complexes containing an ethynyl-
pyrene moiety as the main skeleton. The molecular struc-
tures of these new complexes were fully characterized by
Chem. Eur. J. 2012, 18, 16000 – 16013
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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16009

T. Yi, H.-B. Yang et al.
1.10 ppm (m, 72H); 13C NMR (CDCl3, 75 MHz): d=131.3, 129.8, 125.1,
122.7, 99.7, 96.4, 16.7, 8.3 ppm; 31P NMR (CDCl3, 121.4 MHz): d=
cent organometallic gels. These findings clearly enrich the li-
brary of luminescent organogels and provide a new platform
to design potential functional metallogels and molecular de-
vices.
9.09 ppm (s,
JPtÀP =2323.6 Hz). HRMS (MALDI): m/z calcd for
C72H127I4P8Pt4: 2527.26 [M+H]+; found:2527.2613; elemental analysis
calcd (%) for C72H126I4P8Pt4: C 34.21, H 5.02; found: C 34.18, H 5.066.
General Procedure for the preparation of 1a–4a, 1b–4b, 4a-C6, and 4a-
C18: A 100 mL Schlenk flask was charged with 9a or 9b, the precursors
5–8 and cuprous iodide (7 mol%), degassed, and back-filled three times
with N2. Ethylamine and dried THF were introduced into the reaction
flask by syringe. The reaction was stirred under an inert atmosphere at
room temperature for about 4 h. The solvent was removed by evapora-
tion on a rotary evaporator. The residue was purified by column chroma-
tography on silica gel (dichloromethane/methanol ꢁ99:1) to give 1a–4a
in a reasonable yield. Complexes 1b–4b, 4a-C6, and 4a-C18 were synthe-
sized with the similar procedure for the preparation of 1a–4a, respective-
ly.
Experimental Section
General: All reagents and solvents were purchased from commercial
sources. THF was distilled from sodium, Et2NH was dried from potassi-
um hydroxide; both solvents were degassed under N2 for 30 min before
use. All reactions were performed in standard glassware under an inert
N2 atmosphere. Compound 12, 18, 19, and 22 were prepared as the re-
ported procedure.[29–31] The corresponding alkynes (9a and 9b) were syn-
thesized according to our previous reports.[18] 1H NMR, 13C NMR, and
31P NMR spectra were recorded on Bruker 300 or 400 MHz Spectrometer
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 in-
ternal standard sample of 85% H3PO4 (d=0.0). Coupling constants (J)
are denoted in Hz and chemical shifts (d) in ppm. Multiplicities are de-
noted as follows: s=singlet, d=doublet, m=multiplet, br=broad.
Compound 1a: Pale yellow solid. Yield: 231.9 mg, 92.4%. Rf =0.51 (di-
chloromethane/petroleum ether 2:1); m.p. 938C; 1H NMR (CDCl3,
300 MHz): d=8.72 (d, J=9.0 Hz, 1H), 8.13–7.92 (m, 8H), 6.52 (s, 2H),
3.98–3.90 (m, 6H), 2.27–2.21 (m, 12H), 1.84–1.69 (m, 6H), 1.47–1.23 (m,
72H), 0.90 ppm (br, 9H); 13C NMR (CDCl3, 75 MHz): d=152.6, 137.2,
131.5, 131.3, 131.0, 128.9, 127.3, 126.6, 125.7, 124.8, 124.7, 124.4, 124.3,
123.6, 109.9, 108.6, 73.4, 69.1, 31.9, 30.3, 29.7, 29.62, 29.58, 29.42, 29.37,
29.29, 26.1, 22.6, 16.5, 14.0, 8.3 ppm; 31P NMR (CDCl3, 121.4 MHz): d=
11.70 ppm (s, JPtÀP =2369.8 Hz); MALDI-TOF-MS: m/z calcd for
C74H117O3P2Pt: 1310.80 [M+H]+; found:1310.8; elemental analysis calcd
(%) for C74H116O3P2Pt: C 67.81, H 8.92; found: C 68.09, H 8.814.
UV/Vis spectra were recorded on a Cary 50Bio UV/Visible spectropho-
tometer. Emission spectra were measured on a Cary Eclipse fluorescence
spectrophotometer. Samples for absorption and emission measurements
were contained in 1 cmꢂ1 cm or 1 cmꢂ2 mm quartz cuvettes. SEM
images of the xerogels were obtained using an S-4800 (Hitachi Ltd.) with
an accelerating voltage of 1.0 kV or 10.0 kV. Samples were prepared by
dropping dilute gels onto a silicon wafer.
Compound 1b: Pale yellow solid. Yield: 416.0 mg, 97.0%. Rf =0.59 (di-
chloromethane); m.p. 1408C; 1H NMR (CDCl3, 400 MHz): d=8.73 (d,
J=9.2 Hz, 1H), 8.14–7.94 (m, 8H), 7.70 (s, 1H), 7.51 (d, J=8.0 Hz, 2H),
7.32 (d, J=8.0 Hz, 2H), 7.04 (s, 2H), 4.05–4.00 (m, 6H), 2.29–2.25 (m,
12H), 1.86–1.72 (m, 6H), 1.48–1.27 (m, 72H), 0.91 ppm (br, 9H);
13C NMR (CDCl3, 100 MHz): d = 165.4, 153.1, 141.3, 135.2, 132.9, 131.6,
131.44, 131.36, 131.0, 130.0, 129.0, 128.7, 127.3, 126.7, 126.3, 125.8, 125.1,
124.8, 124.5, 124.3, 119.8, 116.0, 109.3, 108.7, 107.1, 105.7, 73.5, 69.4, 31.9,
30.3, 29.71, 29.70, 29.67, 29.61, 29.55, 29.38, 29.35, 29.33, 26.05, 22.65,
16.5, 14.1, 8.4 ppm; 31P NMR (CDCl3, 161.9 MHz): d=11.86 ppm (s,
General procedure for the preparation of 5–8: A solution of trans-diiodo-
bis (triethyl phosphine)platinum and cuprous iodide (7 mol%) in a mix-
ture of THF/Et2NH was stirred at room temperature. Then ethynyl-
pyrene dissolved in THF was added dropwise to the reaction mixture for
0.5 hour. After another 0.5 h, a small amount of diethylammonium
iodide started precipitating out of solution. The solvent was then re-
moved in vacuo, the resulting residue was separated by column chroma-
tography on silica gel, and product was isolated.
J
PtÀP =2368.60 Hz); MALDI-TOF-MS: m/z calcd for C81H122NO4P2Pt:
1429.85 [M+H]+; found: 1429.3; elemental analysis calcd (%) for
C81H121NO4P2Pt: C 68.04, H 8.53, N 0.98; found: C 68.27, H 8.451, N
0.763.
Compound 5: Pale yellow solid. Yield: 150.3 mg, 67.8%. Rf =0.47 (di-
chloromethane/petroleum ether 2:3); m.p. 2098C; 1H NMR (CDCl3,
300 MHz): d=8.67 (d, J=9.0 Hz, 1H), 8.16–7.94 (m, 8H), 2.33–2.23 (m,
12H), 1.28–1.17 ppm (m, 18H); 13C NMR (CDCl3, 75 MHz): d=131.4,
131.2, 130.9, 128.8, 128.6, 127.2, 126.9, 126.5, 126.1, 125.8, 124.7, 124.6,
124.43, 124.41, 123.8, 99.7, 99.6, 97.3, 16.7, 8.2 ppm; 31P NMR (CDCl3,
121.4 MHz): d=8.90 ppm (s, JPtÀP =2318.8 Hz); HRMS (MALDI): m/z
calcd for C30H39IP2PtNa: 806.11 [M+Na]+; found: 806.1089; elemental
analysis calcd (%) for C30H39IP2Pt: C 45.99, H 5.02; found: C 46.27, H
5.064.
Compound 2a: Golden yellow solid. Yield: 353.1 mg, 79.7%. Rf =0.58
(dichloromethane/petroleum ether 5:1); m.p. 1568C; 1H NMR (CDCl3,
300 MHz): d=8.61 (d, J=9.0 Hz, 2H), 7.97–7.90 (m, 6H), 6.52 (s, 4H),
3.98–3.90 (m, 12H), 2.27–2.23 (m, 24H), 1.84–1.69 (m, 12H), 1.47–1.23
(m, 144H), 0.91 ppm (br, 18H); 13C NMR (CDCl3, 75 MHz): d=152.6,
137.1, 131.5, 129.0, 126.7, 125.6, 124.9, 123.9, 123.6, 109.8, 108.9, 73.4,
69.0, 31.9, 31.7, 30.3, 29.7, 29.6, 29.4, 29.33, 29.31, 26.3, 26.1, 22.9, 22.6,
16.5, 14.1, 8.4 ppm; 31P NMR (CDCl3, 121.4 MHz): d=12.15 (s, JPtÀP
=
Compound 6: Golden yellow solid. Yield: 306.5 mg, 56.2%. Rf =0.48 (di-
chloromethane/petroleum ether 1:1); m.p. 1568C; 1H NMR (CDCl3,
300 MHz): d=8.59 (d, J=9.0 Hz, 2H), 8.00–7.92 (m, 6H), 2.31–2.23 (m,
24H), 1.27–1.16 ppm (m, 36H); 13C NMR (CDCl3, 75 MHz): d=131.4,
129.2, 128.9, 127.0, 125.5, 124.9, 124.1, 123.6, 99.9, 97.1, 16.8, 8.3 ppm;
31P NMR (CDCl3, 121.4 MHz): d=9.52 ppm (s, JPtÀP =2321.2 Hz); ele-
mental analysis calcd (%) for C44H68I2P4Pt2: C 38.72, H 5.02; found: C
38.58, H 5.058.
2367.4 Hz); MALDI-TOF-MS: m/z calcd for C132H223O6P4Pt2: 2418.54
[M+H]+; found: 2418.6; elemental analysis calcd (%) for
C
132H222O6P4Pt2: C 65.53, H 9.25; found: C 64.98, H 9.442.
Compound 2b: Golden yellow solid. Yield: 169.3 mg, 58.1%. Rf =0.47
(dichloromethane/ethyl acetate 50:1); m.p. 1828C; 1H NMR (CDCl3,
400 MHz): d=8.62 (d, J=9.2 Hz, 1H), 7.97–7.92 (m, 6H), 7.65 (s, 2H),
7.49 (d, J=8.4 Hz, 4H), 7.31 (d, J=8.2 Hz, 4H), 7.04 (s, 4H), 4.05–4.00
(m, 12H), 2.28–2.25 (m,24H), 1.86–1.73 (m, 12H), 1.48–1.27 (m, 144H),
0.90 ppm (t, J=6.4 Hz, 18H); 13C NMR (CDCl3, 100 MHz): d=165.4,
153.2, 141.3, 135.1, 131.4, 130.0, 129.1, 129.0, 126.7, 125.7, 125.1, 124.9,
124.0, 123.9, 119.8, 115.5, 109.3, 108.9, 107.2, 105.8, 73.5, 69.4, 31.9, 30.3,
29.71, 29.70, 29.67, 29.63, 29.62, 29.55, 29.38, 29.35, 29.33, 26.05, 22.66,
22.65, 16.5, 14.1, 8.4 ppm; 31P NMR (CDCl3, 161.9 MHz): d=11.69 ppm
(s, JPtÀP =2373.45 Hz); MALDI-TOF-MS: calcd for C146H233N2O8P4Pt2:
2656.62 [M+H]+; found: 2656.2; elemental analysis calcd (%) for
C146H232N2O8P4Pt2: C 65.99, H 8.80; N, 1.05; found: C 65.10, H 8.633; N,
0.714.
Compound 7: Golden-yellow solid. Yield: 876.5 mg, 53.6%. Rf =0.45 (di-
chloromethane/petroleum ether 1:1); m.p. 1258C; 1H NMR (CDCl3,
300 MHz): d=8.66 (s, 2H), 7.99–7.91 (m, 6H), 2.31–2.27 (m, 24H), 1.27–
1.17 ppm (m, 36H); 13C NMR (CDCl3, 75 MHz): d=131.3, 129.4, 128.7,
126.6, 125.9, 124.8, 124.3, 123.4, 99.9, 97.1, 16.7, 8.3 ppm; 31P NMR
(CDCl3, 121.4 MHz): d=9.33 ppm (s,
JPtÀP =2321.2 Hz); HR-MALDI
MS: m/z calcd for C44H69I2P4Pt2: 1365.17 [M+H]+; found:1365.1; elemen-
tal analysis calcd (%) for C44H68I2P4Pt2: C 38.72, H 5.02; found: C 38.38,
H 5.038.
Compound 8: Orange-red solid. Yield: 137.0 mg, 32.0%. Rf =0.63 (di-
chloromethane/petroleum ether 3:2); m.p.>3008C; 1H NMR (CDCl3,
300 MHz): d=8.51 (s, 4H), 7.88 (s, 2H), 2.30–2.27 (m, 48H), 1.27–
Compound 3a: Golden yellow solid. Yield: 327.9 mg, 92.1%. Rf =0.43
(dichloromethane/petroleum ether 5:2); m.p. 1258C; 1H NMR (CDCl3,
16010
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Chem. Eur. J. 2012, 18, 16000 – 16013

Platinum-Acetylide Organogelators
FULL PAPER
300 MHz): d=8.69 (s, 2H), 7.95 (d, J=7.8 Hz, 2H), 7.93 (s, 2H), 7.89 (d,
J=7.2 Hz, 2H), 6.52 (s, 4H), 3.98–3.90 (m, 12H), 2.28–2.23 (m, 24H),
1.81–1.71 (m, 12H), 1.47–1.23 (m, 144H), 0.88 ppm (t, J=6.6 Hz, 18H);
13C NMR (CDCl3, 75 MHz): d = 152.5, 137.1, 131.3, 129.1, 128.7, 126.3,
125.9, 124.8, 124.0, 123.7, 123.5, 109.8, 108.8, 73.3, 68.9, 31.8, 31.6, 30.2,
29.63, 29.58, 29.55, 29.35, 29.32, 29.27, 29.25, 26.0, 22.8, 22.6, 22.3, 16.4,
mental analysis calcd (%) for C320H578O12P8Pt4: C 68.07, H 10.32; found:
C 67.78, H 10.62.
14.0, 8.3 ppm; 31P NMR (CDCl3, 121.4 MHz): d=11.78 ppm (s, JPtÀ
=
P
Acknowledgements
2374.6 Hz); MALDI-TOF-MS: calcd for C132H223O6P4Pt2: m/z 2418.54
[M+H]+; found: 2418.4692; elemental analysis calcd (%) for
This work was financially supported by NSFC/China (Nos. 91027005,
91022021, 21125104, and 20902027), Shanghai Shuguang Program
(09SG25), Innovation Program of SMEC (10ZZ32), RFDP
(20100076110004) of Higher Education of China, and Fok Ying Tung Ed-
ucation Foundation.
C
132H222O6P4Pt2: C 65.53, H 9.25; found: C 65.89, H 9.346.
Compound 3b: Golden yellow solid. Yield: 240 mg, >99%. Rf =0.58 (di-
chloromethane/ethyl acetate 50:1); m.p. 2108C; 1H NMR (CDCl3,
400 MHz): d=8.69 (d, J=9.2 Hz, 2H), 7.96–7.91 (m, 4H), 7.88 (s, 2H),
7.63 (s, 2H), 7.49 (d, J=8.2 Hz, 4H), 7.31 (d, J=8.2 Hz, 4H), 7.04 (s,
4H), 4.06–4.00 (m, 12H), 2.28–2.26 (m,24H), 1.84–1.71 (m, 12H), 1.48–
1.26 (m, 144H), 0.88 ppm (t, J=6.4 Hz, 18H); 13C NMR (CDCl3,
100 MHz): d=165.5, 153.1, 141.2, 135.3, 131.4, 131.3, 129.9, 129.2, 128.9,
126.3, 126.0, 124.8, 124.1, 123.7, 119.8, 115.3, 109.3, 109.0, 106.8, 105.7,
73.4, 69.2, 31.9, 30.3, 29.68, 29.64, 29.62, 29.58, 29.52, 29.4, 29.3, 26.0, 22.6,
16.6, 14.0, 8.4 ppm; 31P NMR (CDCl3, 161.9 MHz): d=11.68ppm (s,
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PtÀP =2366.98 Hz); HR-MALDI MS of 3b: m/z: calcd for
C146H233N2O8P4Pt2 [M+H]+ 2655.62; found: 2655.6; elemental analysis
calcd (%) for C146H232N2O8P4Pt2: C 65.99, H 8.80, N 1.05; found: C 65.87,
H 8.698, N 0.840.
Compound 4a: Orange-red solid. Yield: 222.5 mg, 75.3%. Rf =0.44 (di-
chloromethane); m.p. 658C; 1H NMR (CDCl3, 300 MHz): d=8.51 (s,
4H), 7.87 (s, 2H), 6.52 (s, 8H), 3.98–3.90 (m, 24H), 2.27–2.23 (m, 48H),
1.81–1.71 (m, 24H), 1.47–1.22 (m, 288H), 0.88 ppm (t, J=6.6 Hz, 36H);
13C NMR (CDCl3, 75 MHz): d=152.6, 137.1, 129.8, 125.2, 123.6, 122.8,
113.9, 109.9, 109.7, 108.9, 105.6, 73.5, 69.1, 31.9, 30.3, 29.71, 29.68, 29.64,
29.4, 29.3, 26.1, 22.7, 16.5, 14.1, 8.4 ppm; 31P NMR (CDCl3, 121.4 MHz):
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d=11.78 ppm (s,
JPtÀP =2379.4 Hz); MALDI-TOF-MS: calcd for
C248H435O12P8Pt4: m/z 4633.99 [M+H]+; found: 4633.975; elemental anal-
ysis calcd (%) for C248H434O12P8Pt4: C 64.25, H 9.44; found: C 64.72, H
9.485.
Compound 4b: Orange-red solid. Yield: 233.0 mg, >99%. Rf =0.60 (di-
chloromethane/ethyl acetate 100:3); m.p. 2228C; 1H NMR (CDCl3,
400 MHz): d=8.53 (s, 4H), 7.89 (s, 2H), 7.63 (s, 4H), 7.49 (d, J=8.2 Hz,
8H), 7.31 (d, J=8.2 Hz, 8H), 7.04 (s, 8H), 4.06–4.00 (m, 24H), 2.28–2.26
(m, 48H), 1.86–1.72 (m, 24H), 1.48–1.27 (m, 288H), 0.88 ppm (t, J=
6.0 Hz, 36H); 13C NMR (CDCl3, 100 MHz): d=165.5, 153.0, 141.2, 135.3,
131.9, 131.4, 129.9, 125.1, 125.0, 122.7, 119.8, 114.0, 109.3, 109.0, 107.0,
105.7, 73.4, 69.2, 31.9, 30.3, 29.67, 29.64, 29.58, 29.51, 29.4, 29.3, 26.0, 22.6,
16.5, 14.0, 8.5 ppm; 31P NMR (CDCl3, 161.9 MHz): d=11.67 ppm (s, JPtÀ
P =2371.84 Hz); MALDI-TOF-MS: calcd for C276H455N4O16P8Pt4: m/z
5110.14 [M+H]+; found: 5110.4; elemental analysis calcd (%) for
C276H454N4O16P8Pt4: C 64.84, H 8.95; N, 1.10; found: C 64.87, H 8.727; N,
0.871.
Compound 4a-C6: Orange-red solid. Yield: 222.5 mg, 99.0%. Rf =0.65
(ethyl acetate/petroleum ether 1:6); m.p. 1548C; 1H NMR (CDCl3,
300 MHz): d=8.51 (s, 4H), 7.87 (s, 2H), 6.52 (s, 8H), 3.98–3.90 (m,
24H), 2.26–2.23 (m, 48H), 1.83–1.69 (m, 24H), 1.47–1.22 (m, 144H),
0.91 ppm (br, 36H); 13C NMR (CDCl3, 75 MHz): d=152.7, 137.2, 132.1,
132.0, 131.9, 129.9, 125.1, 123.7, 122.9, 109.9, 108.9, 73.5, 69.1, 31.8, 31.6,
30.3, 29.4, 26.0, 25.8, 22.7, 22.6, 16.6, 14.1, 14.0, 8.5 ppm; 31P NMR
(CDCl3, 121.4 MHz): d=11.79 ppm (s, JPtÀP =2374.6 Hz); HR-MALDI
MS of 4a-C6: m/z calcd for C176H291O12P8Pt4 [M+H]+ 3624.87; found:
3624.8686; elemental analysis calcd (%) for C176H290O12P8Pt4: C 58.29, H
8.06; found: C 58.43, H 8.253.
Compound 4a-C18: Orange solid. Yield: 268.3 mg, 98.1%. Rf =0.45 (di-
chloromethane/petroleum ether 3:1); m.p. 818C; 1H NMR (CDCl3,
300 MHz): d=8.51 (s, 4H), 7.87 (s, 2H), 6.52 (s, 8H), 3.97–3.90 (m,
24H), 2.28–2.23 (m, 48H), 1.81–1.71 (m, 24H), 1.46–1.22 (m, 432H), 0.87
(t, J=6.9 Hz, 36H); 13C NMR (CDCl3, 75 MHz): d=152.7, 137.1, 129.8,
125.1, 123.6, 122.8, 113.9, 109.9, 109.7, 108.9, 105.6, 73.5, 69.1, 31.9, 30.3,
29.7, 29.6, 29.5, 29.3, 26.1, 22.7, 16.5, 14.1, 8.4 ppm; 31P NMR (CDCl3,
121.4 MHz): d=12.18 ppm (s,
JPtÀP =2379.4 Hz); MALDI-TOF-MS:
calcd for C320H579O12P8Pt4: m/z 5643.12 [M+H]+; found: 5643.2263; ele-
Chem. Eur. J. 2012, 18, 16000 – 16013
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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Received: August 14, 2012
Published online: November 7, 2012
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