Synthesis and characterization of multipyrene-modified platinum acetylide oligomers

Article abstract of DOI:10.1007/s00706-012-0892-4

A series of new multipyrene-modified platinum acetylide oligomers were successfully synthesized utilizing the coupling reaction of trans-Pt complexes with C-H bonds in alkynes as the key step. These new conjugated oligomers were characterized by multinuclear NMR (¹H, ¹³C, and ³¹P) and mass spectrometry (MALDI-TOF-MS). Preliminary spectroscopic studies of these oligomers were also carried out.

Full text of DOI:10.1007/s00706-012-0892-4

Monatsh Chem (2013) 144:553–566
DOI 10.1007/s00706-012-0892-4
ORIGINAL PAPER
Synthesis and characterization of multipyrene-modified platinum
acetylide oligomers
•
Nai-Wei Wu Jing Zhang Cui-Hong Wang
•
•
•
Lin Xu Hai-Bo Yang
Received: 28 September 2012 / Accepted: 25 November 2012 / Published online: 9 January 2013
Ó Springer-Verlag Wien 2012
Abstract A series of new multipyrene-modified platinum
acetylide oligomers were successfully synthesized utilizing
the coupling reaction of trans-Pt complexes with C–H
bonds in alkynes as the key step. These new conjugated
oligomers were characterized by multinuclear NMR (1H,
13C, and 31P) and mass spectrometry (MALDI-TOF–MS).
Preliminary spectroscopic studies of these oligomers were
also carried out.
light detectors [20, 21], solid-state lasers [22–24], and
sensors [25, 26].
Recently, the incorporation of some identical chromoph-
ores into a conjugated oligomer to construct multichro-
mophoric conjugated oligomers has evolved to be one of the
most attractive fields in photochemistry and materials science
[27–31]. The arraying of multiple chromophores at close
proximity with one another leads to interesting and novel
properties, fueling the design of novel materials for many
applications. In addition to the aforementioned properties
of conjugated oligomers, multichromophoric conjugated
oligomers offer many advantages compared to the single
chromophoric conjugated analogues. For example, the
collective absorption of multichromophoric conjugated
oligomers is usually higher, which is particularly useful in
light-harvesting applications in solar cell research [32–34].
Moreover, some new features, such as physical, optical,
electrochemical, and photochemical properties, have been
observed in multichromophoric conjugated oligomers
[35, 36]. For instance, interactions between components in the
ground state and excited state usually result in the formation
of new complexes such as excimers and exciplexes [37, 38].
These complexes typically exhibit broadened absorptions and
red-shifted emission spectra. Finally, the properties of mul-
tichromophoric conjugated oligomers can readily be adjusted
to suit some application needs through geometric and
directional control of the complexes because the relative
orientation and arrangement of chromophores play a crucial
role in their photophysical properties [27, 39]. Thus,
numerous efforts have been taken to construct novel multi-
chromophoric conjugated oligomers.
Keywords Pyrene Á Sonogashira coupling reaction Á
Organometallic compounds Á Absorption spectrum Á
Fluorescence spectroscopy
Introduction
During the past few decades, conjugated oligomers have
attracted increasing attention in chemistry and materials
science owing to their interesting electrical, optical, and
optoelectronic properties [1–7]. These excellent properties
make them suitable for a range of promising applications,
such as organic light-emitting diodes (OLEDs) [8–11],
solar cells [12–15], field-effect transistors (FETs) [16–19],
Electronic supplementary material The online version of this
article (doi:10.1007/s00706-012-0892-4) contains supplementary
material, which is available to authorized users.
N.-W. Wu Á J. Zhang Á C.-H. Wang Á L. Xu (&) Á
H.-B. Yang (&)
Shanghai Key Laboratory of Green Chemistry and Chemical
Processes, Department of Chemistry, East China Normal
University, Shanghai 200062, People’s Republic of China
e-mail: lxu@chem.ecnu.edu.cn
As mentioned above, the wide range of applications
of multichromophoric conjugated oligomers has prompted
the need to develop efficient methods to synthesize
them. However, it is still very challenging to realize the
H.-B. Yang
e-mail: hbyang@chem.ecnu.edu.cn
123

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N.-W. Wu et al.
well-controlled synthesis of desired multichromophoric
conjugated oligomers. Owing to its ease of synthesis and
favorable optical properties, the platinum acetylide skele-
ton has been widely used as a connecting bridge to
construct conjugated oligomers [40–43]. In our previous
research, we synthesized a series of platinum acetylide-
containing building blocks, which have been employed to
prepare supramolecular metallacycles and organometallic
gels [44–49]. Moreover, platinum has a large spin–orbit
coupling constant and consequently p-conjugated materials
that contain this element typically exhibit high triplet
yields and efficient phosphorescence [50–55]. Therefore,
platinum acetylide-containing conjugated oligomers have
been widely studied because they represent a class of
materials with a high quantum efficiency of phosphores-
cence. Platinum acetylide-containing conjugated oligomers
have also been used in various optoelectronic fields [51].
However, there have been very few successful examples of
the construction of multichromophoric conjugated oligo-
mers by using p-conjugated platinum acetylide moieties as
the main skeleton, perhaps because of difficulties with their
synthesis.
13C, and 31P) and mass spectrometry (MALDI-TOF–MS).
A preliminary study of their spectroscopic behavior was
also carried out.
Results and discussion
Synthesis of multipyrene platinum acetylide conjugated
oligomers
The acidity of C–H bonds in alkynes induced by transition
metals has received considerable attention in organome-
tallic chemistry. Herein, we utilized the coupling reaction
of trans-Pt complexes with C–H bonds in alkynes as the
key step in the synthesis of all multipyrene-modified plat-
inum acetylide conjugated oligomers. The synthesis of
tetrakis-pyrene conjugated oligomer 15 involved a series of
Pd-catalyzed cross-coupling reactions starting from 1,3,5-
tribromobenzene as shown in Scheme 2. Pyrene motifs
were introduced by a Sonogashira coupling reaction of 1
with 1-ethynylpyrene to afford 2, followed by deprotection
with NaOH in toluene to afford 3. Compound 3 was then
reacted with 2 equiv of trans-PtI2(PEt3)2 to give iodo-
metal complex 4. Subsequent coupling reactions of 4 with
5 resulted in the formation of trimethylsilyl protected 6
with two pyrenes in 72 % yield. Then further deprotection
and coupling reactions were performed to get target com-
plex 15.
Pyrene is a polycyclic aromatic hydrocarbon consisting
of four fused benzene rings and it has received significant
attention owing to its interesting optical properties such as
relatively long excited-state lifetimes and exceptional dis-
tinction of the fluorescence bands for monomer and
excimer [56, 57]. In particular, the tendency of pyrene to
form excimers has been widely employed for probing the
structural properties of macromolecular systems [58]. In
addition to the excimer sensing, there has been a recent
increased interest in the use of pyrenes as optoelectronic
materials [59–62]. Recently, multipyrene-modified oligo-
mers have evolved to be one of the most attractive targets
within materials science as it is expected to possess better
fluorescent and electroluminescent properties than those
of the pyrene monomer, because of its longer delocalized
p-electron chain sequence. Thus, multipyrene-modified
oligomers have been used as active components in
molecular electronic devices such as OLEDs, OFETs, and
solar cells [63–66].
Two other oligomers 16 and 17 with geometric struc-
tural similarity to 15 were obtained through similar
procedures in satisfactory yields as outlined in Schemes 3
and 4, respectively.
In all cases, the desired complexes were purified by
column chromatography on silica gel using dichlorometh-
ane as eluent and obtained as yellow solids with high
purity. They exhibited good solubility in common organic
solvents such as CH2Cl2 and CHCl3. Moreover, these
newly designed oligomers are air- and humidity-stable at
room temperature.
Structure characterization
Inspired in part by our successful results on the synthesis
of platinum acetylide building blocks, we envisioned that
the synthesis of a series of platinum acetylide-containing
multipyrene conjugated oligomers with a varying number
of pyrene units could be realized via a convergent strategy.
It should be noted that these novel multipyrene conjugated
oligomers are of special interest owing to their potential
applications in the optoelectronics field. Herein, we present
the synthesis of a series of novel platinum acetylide-con-
taining multipyrene conjugated oligomers with a varying
number of pyrene units (Scheme 1). The structures of all
complexes were characterized by multinuclear NMR (1H,
Multinuclear NMR (1H, 13C, and 31P) analysis of all multi-
pyrene-modified platinum acetylide oligomers 15–17
revealed the formation of discrete and symmetric species.
The room-temperature 31P NMR spectra of oligomers
15–17 displayed a sharp singlet (d = 11.6 ppm for 15,
11.3 ppm for 16, and 11.6 ppm for 17) accompanied
by platinum satellites (JPt–P = 2,362.77 Hz for 15,
2,358.07 Hz for 16, and 2,369.73 Hz for 17), which is con-
sistent with the trans configuration around the Pt(II) atom. It
should be noted that the singlet in each 31P NMR spectra of
15–17 exhibited a small downfield shift from the iodo-metal
123

Synthesis and characterization of multipyrene-modified platinum acetylide oligomers
555
PEt3
Et3P
PEt3
Pt
Et3P
PEt3
Pt
P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
Et3
P
PEt3
Pt
P
Pt
Et3P
Pt
PEt3
Pt
PEt3
Et3
Et3
15
16
PEt3
Pt
Et3P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
17
Scheme 1
precursors by 2.7, 2.4, and 2.5 ppm, respectively (Fig. 1).
This change, as well as the increase in coupling of the
flanking 195Pt satellites (ca. DJ = ?42 Hz for 15, ?36 Hz
for 16, and ?48 Hz for 17), might be caused by the electron-
withdrawing effect of the large p-conjugate bridges.
existence of target multipyrene-modified platinum acety-
lide complexes.
Simulated molecular models
Usually matrix-assisted laser desorption/ionization time
of flight mass spectrometry (MALDI-TOF–MS) studies
allow the complexes to remain intact during the analysis
process and provide the high resolution required for the
unambiguous determination of their absolute molecular
weight and molecularity. MALDI-TOF–MS investigation
of multipyrene-modified oligomers 15–17 was therefore
carried out. Because of the high molecular weight and
complex isotope splitting of such multipyrene-modified
oligomers, it is difficult to get strong mass signals even
under MALDI-TOF–MS conditions. However, with con-
siderable effort, satisfactory high resolution MALDI-TOF–
MS results of 15–17 were obtained, which unambiguously
support the formation of multipyrene-modified platinum
acetylide oligomers with different length (Fig. 2). For
example, the MALDI-TOF–MS spectra of 15–17 exhibited
a strong signal of 2,640.50, 4,203.09, and 5,767.65,
respectively, corresponding to the [M?H]? species. Thus,
MALDI-TOF–MS results provided strong support for the
All attempts to grow X-ray-quality single crystals of mul-
tipyrene conjugated oligomers 15–17 have proven to be
unsuccessful to date. Thus, PM6 semi-empirical molecular
orbital methods were employed to optimize the geometry of
all oligomers. In the optimized structure of each platinum
acetylide oligomer, two phenyl acetylides are r-bonded to
platinum in a trans configuration. Coordination around the
platinum atoms is square planar with slight tetrahedral
distortions. Moreover, upon increasing the number of pyr-
ene units, extended molecular length (4.5 nm for 15, 6.5 nm
for 16, and 8.1 nm for 17) was observed (Fig. 3).
Absorption and emission properties
The absorption and emission properties of this series of
multipyrene-modified platinum acetylide were investigated
in dilute dichloromethane solution (ca. 10-6 M) and the
data are collected in Table 1 and Fig. 4. The absorption
spectra of 15–17 are structurally similar to each other and
123

556
N.-W. Wu et al.
Br
Br
OH
TMSA
Pd(PPh3)4, CuI
THF, i-Pr2NH
65 °C,12 h
65 °C,12h
51%
Pd(PPh3)4, CuI, Et3N
65 °C,12 h, 73%
Br
Br
TMS
OH
1
TMS
2
OH
NaOH, toluene
trans-Pt(PEt3)2I2, CuI
5
130 °C, 30 min
70%
THF, Et2NH
rt, 2 h, 88%
CuI, THF, Et2NH
rt, 1.5 h, 72%
PEt3
Pt
Et3P
PEt3
Pt
TMS
TMS
TMS
I
6
3
4
Et3P
trans-Pt(PEt3)2I2, CuI
K2CO3
THF, Et2NH
rt, 2 h, 70%
CH3OH, THF, rt, 2 h
97%
Et3P
PEt3
Pt
Et3P
PEt3
Pt
Pt
PEt3
H
I
Et3P
8
7
PEt3
Pt
Et3P
Et3P
PEt3
Pt
Et3P
7
Compound
Pt
PEt3
CuI, THF, Et2NH
rt, 1.5 h, 73%
15
Scheme 2
show a broad and structureless band around 220–290 and
300–400 nm. Within previous spectroscopic work on
trans-[Pt(PEt3)2(C:CR)2] the absorption bands at
approximately 300–360 nm were assigned as metal-to-
ligand charge transfer (MLCT) transitions [55, 67, 68].
Moreover, the low energy absorption bands (300–400 nm)
123

Synthesis and characterization of multipyrene-modified platinum acetylide oligomers
557
CuI, THF, Et2NH
rt, 1.5 h, 78%
+
Et3P
Pt
PEt3
PEt3
Pt
Et3P
TMS
PEt3
I
PEt3
Pt
Et3P
TMS
Pt
Et3P
4
7
9
Et3P
Pt
PEt3
PEt3
Pt
Et3P
PEt3
Pt
Et3P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
I
H
trans-Pt(PEt3)2I2
K2CO3
THF, Et2NH
rt, 2 h, 70%
CH3OH, THF
rt, 2 h, 85%
11
10
Compound 10
CuI, THF, Et2NH
rt, 1.5 h, 51%
PEt3
Pt
Et3P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
16
Scheme 3
in oligomers 15–17 may involve an admixture of intrali-
gand (IL) and MLCT transitions. The higher energy
absorption bands (ca. 220–290 nm) in oligomers 15–17
were dominated by intraligand p–p* transitions of aromatic
pyrene rings [69]. Their absorption coefficients (e) were
enhanced with the increase of oligomer length because the
effective concentration of pyrene was increasing [70].
Likewise, their fluorescence intensity increased with the
increase of oligomer length, which might be also due to the
higher effective concentration of pyrene. Interestingly, in
the case of 17, a shoulder band at 500 nm was found in the
emission spectrum. This finding indicated that it was much
123

558
N.-W. Wu et al.
Et3P
Pt
PEt3
PEt3
Pt
Et3P
Et3
P
Pt
PEt3
Pt
Et3P
Et3P
Pt
PEt3
CuI, THF, Et2NH
rt, 1.5 h, 78%
TMS
H
+
PEt3
PEt3
Pt
Et3P
TMS
I
12
10
4
Et3P
Pt
PEt3
Pt
Et3P
Et3P
Pt
PEt3
PEt3
Pt
Et3P
Et3
P
PEt3
Pt
Et3P
Et3P
Pt
PEt3
I
H
Pt
PEt3
trans-Pt(PEt3)2I2
K2CO3
PEt3
CH3OH, THF, rt
2 h, 70%
THF, Et2NH
rt, 2 h, 70%
14
13
Compound 13
PEt3
Pt
Et3P
Et3P
Pt
PEt3
Pt
Et3P
Et3P
Pt
PEt3
Pt
Et3P
Et3
P
Pt
PEt3
Pt
Et3P
CuI, THF, Et2NH
rt, 1.5 h, 92%
PEt3
PEt3
PEt3
17
Scheme 4
easier for 17 to form excimers when compared to 15 and
16. It is well known that the formation of pyrene excimers
requires the complexation of an excited-state molecule
with a ground-state molecule. Increasing the density of
pyrene molecules assembled in conjugated oligomers
enhances the probability of forming excited-state excimers.
Surprisingly, it was found that the fluorescence quantum
yields of these conjugated oligomers decreased with the
increase of oligomer length. Usually the molecular skeleton
becomes more flexible when the length of oligomer
increases. Thus, in the longer oligomers, intersystem
crossing and nonradiative decay processes might to some
extent compete with the fluorescence radiation process. All
of the above results indicated that the length of multipy-
rene-modified oligomers has a different effect on the
absorption coefficient, fluorescence quantum yield, and
the formation of excimers. Thus, these multipyrene con-
jugated oligomers are promising models to understand
the fundamental properties of their analogous polydisperse
polymers.
Conclusions
By employing the coupling reaction of trans-Pt complexes
with C–H bonds in alkynes as the key step, we have
123

Synthesis and characterization of multipyrene-modified platinum acetylide oligomers
559
Fig. 1 Partial 31P NMR spectra (400 MHz, CDCl3, 298 K) of 15 (a), 16 (b), and 17 (c)
1
successfully prepared a new family of multipyrene-modi-
fied platinum acetylide oligomers from simple starting
materials in satisfactory yields via a convergent strategy.
Multinuclear NMR (1H, 13C, and 31P) analysis of all con-
jugated oligomers was carried out. The sharp NMR signals
in both 31P{1H} and H NMR spectra along with the sol-
ubility of these species confirm the formation of such
oligomers. Moreover, mass spectrometric (MALDI-TOF–
MS) studies provided further evidence for the unambiguous
determination of their absolute molecular weight and
123

560
N.-W. Wu et al.
Fig. 2 MALDI-TOF–MS spectra of 15 (a), 16 (b), and 17 (c)
molecularity. All conjugated oligomers exhibit remarkable
solubility in common organic solvents, such as dichloro-
methane and chloroform. Furthermore, these newly designed
conjugated oligomers are air- and humidity-stable at room
temperature. The preliminary spectroscopic studies indicated
that the length of multipyrene conjugated oligomers has a
different effect on the absorption coefficient, fluorescence
quantum yield, and the formation of excimers. All obtained
123

Synthesis and characterization of multipyrene-modified platinum acetylide oligomers
561
Fig. 3 Simulated molecular
model of 15 (a), 16 (b), and 17
(c) optimized with PM6 semi-
empirical molecular orbital
methods
Table 1 UV–vis absorption and emission data for complexes 15–17
Compound (concentration/M)
k
abs/nm
e/M-1 cm-1
kF/nm
AF
15 (1.0 9 10-6
16 (1.0 9 10-6
17 (1.0 9 10-6
)
)
)
391
366
286
391
366
286
392
366
286
72,165
92,415
398
418
0.023
0.014
0.011
48,355
171,095
218,055
162,760
284,410
357,870
287,875
398
419
398
419
491
123

562
N.-W. Wu et al.
Fig. 4 UV–vis absorption (left) and fluorescence spectra (right) of 15–17 (all of them 1 lM) in CH2Cl2
12 h at 65 °C, then 0.93 cm3 2-methyl-3-butyn-2-ol
(9.53 mmol) was added through a syringe and the mixture
was allowed to continue stirring for 12 h. Then insoluble
materials were filtrated through filter paper and the solvent
was removed by evaporation on a rotary evaporator. The
residue was purified by column chromatography on silica
gel with petroleum ether (PE)/acetone (15:1, v/v) as eluent
to afford colorless liquid 1 with a yield of 51 %. Rf = 0.58
(PE/acetone, 10:1, v/v); 1H NMR (CDCl3, 400 MHz):
d = 7.53 (s, 1H), 7.49 (s, 1H), 7.44 (s, 1H), 2.02 (br, 1H),
1.59 (s, 6H), 0.22 (s, 9H) ppm; 13C NMR (CDCl3,
100 MHz): d = 134.28, 134.21, 133.60, 125.10, 124.67,
121.68, 103.15, 95.63, 94.84, 79.98, 31.33, -0.24 ppm;
HRMS: m/z calcd for C16H19BrOSi 334.0389, found
334.0388.
results obviously enrich the library of functionalized conju-
gated oligomers and provide a new platform to design
potential functional organometallic complexes and molecu-
lar devices.
Experimental
Toluene and THF were distilled from sodium; diethyl-
amine was dried over potassium hydroxide; all of them
were degassed under N2 for 30 min before use. NMR
solvents (CDCl3) and all other reagents were of commer-
cial quality and used without further purification.
1H NMR, 13C NMR, and 31P NMR spectra were
recorded on
a
Bruker 400 MHz spectrometer (1H:
400 MHz, 13C: 100 MHz, 31P: 162 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
(d = 0.0). Coupling constants (J) are denoted in Hz and
chemical shifts (d) in ppm. Multiplicities are denoted as
follows: s = singlet, d = doublet, t = triplet, m = multi-
plet. Melting points were determined with an X-4 micro-
melting point apparatus.
[[3-Ethynyl-5-(pyren-1-ylethynyl)phenyl]ethynyl]-
trimethylsilane (3, C31H22Si)
A 100-cm3 Schlenk flask was charged with 1.64 g 1
(4.88 mmol), 282 mg Pd(PPh3)4 (0.24 mmol), 46 mg CuI
(0.24 mmol), 1.10 g 1-ethynylpyrene (4.86 mmol), and
30 cm3 Et3N under nitrogen atmosphere. The reaction
mixture was stirred for 12 h at 65 °C, then insoluble
materials were filtrated through filter paper and the solvent
was then removed by evaporation on a rotary evaporator.
The residue was purified by column chromatography on
silica gel with PE/acetone (20:1, v/v) as eluent to afford 2
with a yield of 73 %. A mixture of 400 mg 2 (0.83 mmol)
and 166 mg NaOH (4.15 mmol) in 10 cm3 dry toluene was
refluxed for 0.5 h. The filtrate was evaporated to give a
dark yellow residue. The residue was purified by column
chromatography on silica gel with PE/DCM (5:1, v/v) as
eluent to afford yellow solid 3 with a yield of 70 %.
Rf = 0.54 (PE/DCM, 5;1, v/v); 1H NMR (CDCl3,
400 MHz): d = 8.59 (d, J = 9.2 Hz, 1H), 8.23–8.01 (m,
8H), 7.80 (s, 1H), 7.77 (s, 1H), 7.62 (s, 1H), 3.16 (s, 1H),
0.31 (s, 9H) ppm; 13C NMR (CDCl3, 100 MHz):
UV–vis spectra were recorded on 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 quartz cuvettes.
4-[3-Bromo-5-[(trimethylsilyl)ethynyl]phenyl]-2-methyl-
but-3-yn-2-ol (1, C16H19BrOSi)
Under an atmosphere of nitrogen, 3.00 g 1,3,5-tribromo-
benzene (9.53 mmol), 275 mg Pd(PPh3)4 (0.24 mmol),
45 mg CuI (0.24 mmol), and 1.38 cm3 trimethylsilylacet-
ylene (9.53 mmol) were dissolved in 30 cm3 THF and
30 cm3 i-Pr2NH. The reaction mixture was stirred for
123

Synthesis and characterization of multipyrene-modified platinum acetylide oligomers
563
d = 134.93, 134.73, 131.90, 131.41, 131.08, 130.89,
129.53, 128.39, 128.26, 127.08, 126.16, 125.67, 125.60,
125.19, 124.39, 124.28, 124.22, 124.11, 123.99, 122.85,
116.90, 103.18, 96.03, 93.08, 90.01, 82.03, 78.45,
-0.10 ppm; HRMS: m/z calcd for C31H22Si 422.1491,
found 422.1493.
3.19 (s, 1H) ppm; 13C NMR (CDCl3, 100 MHz):
d = 135.11, 131.85, 131.81, 131.31, 131.11, 130.92,
129.51, 128.51, 128.31, 128.15, 127.09, 126.13, 125.60,
125.54, 125.27, 124.39, 124.32, 124.15, 123.93, 122.56,
117.23, 93.94, 89.45, 82.88, 77.92 ppm; HRMS: m/z calcd
for C26H14 326.1096, found 326.1094.
[[3-(Pyren-1-ylethynyl)-5-[(trimethylsilyl)-
ethynyl]phenyl]ethynyl]bis(triethylphosphine)-
platinum(IV) iodide (4, C43H51IP2PtSi)
[[3-Ethynyl-5-(pyren-1-ylethynyl)phenyl]ethynyl]-
[[3-(pyren-1-ylethynyl)phenyl]ethynyl]bis-
(triethylphosphine)platinum (7, C66H56P2Pt)
CuI (9.5 mg, 0.03 mmol), 1.36 g trans-Pt(PEt3)2I2
(1.98 mmol), and 420 mg 3 (0.99 mmol) were added to a
mixed solvent of 30 cm3 THF and 30 cm3 Et2NH
under an atmosphere of nitrogen. The mixture was then
stirred at room temperature for 2 h. The solvent was
removed in vacuo and the residue was purified via
column chromatography with PE/DCM (8:1, v/v) as
eluent to afford yellow solid 4 with a yield of 88 %.
Rf = 0.43 (PE/DCM, 2:1, v/v); 1H NMR (CDCl3,
400 MHz): d = 8.65 (d, J = 8.8 Hz, 1H), 8.25–8.02
(m, 8H), 7.64 (s, 1H), 7.53 (s, 1H), 7.36 (s, 1H), 2.24
(br, 12H), 0.29 (s, 9H) ppm; 31P NMR (CDCl3, 161.9
MHz): d = 8.94 (JPt–P = 2,313.55 Hz) ppm; 13C NMR
(CDCl3, 100 MHz): d = 133.63, 133.53, 131.91, 131.81,
131.32, 131.17, 130.97, 129.54, 129.10, 128.33, 128.21,
127.15, 126.22, 125.62, 125.36, 124.46, 124.40, 124.22,
123.63, 123.44, 117.38, 104.19, 98.85, 94.82, 94.13,
92.46, 89.00, 16.65, 8.28, -0.04 ppm; MALDI HRMS:
m/z calcd for C43H51IP2PtSi ([M?H]?) 980.19, found
980.14.
A 50-cm3 Schlenk flask was charged with 6.0 mg CuI
(0.03 mmol), 617 mg 4 (0.63 mmol), and 308 mg 5
(0.94 mmol), then a mixed solvent of 10 cm3 THF and
10 cm3 Et2NH was added under an atmosphere of nitrogen.
The mixture was then stirred at room temperature for 1.5 h.
The solvent was removed in vacuo and the residue was
purified via column chromatography with PE/DCM (3:1, v/v)
as eluent to afford yellow solid 6 with a yield of 72 %. Then
627 mg 6 (0.53 mmol) was dissolved in a mixture of 10 cm3
THF and 10 cm3 methanol, 294 mg K2CO3 (2.13 mmol) was
added, and the solution was stirred at room temperature for
2.0 h. The filtrate was evaporated to give a dark yellow
residue. The residue was purified by column chromatography
onsilicagel withPE/DCM(1:1, v/v)aseluenttoaffordyellow
solid 7 with a yield of 97 %. Rf = 0.50 (PE/DCM, 1:1, v/v);
1H NMR (CDCl3, 400 MHz): d = 8.66–8.64 (m, 2H),
8.25–8.02 (m, 16H), 7.62 (s, 2H), 7.58 (s, 1H), 7.50 (d,
J = 7.2 Hz, 1H), 7.41 (s, 1H), 7.33–7.29 (m, 2H), 3.11 (s,
1H), 2.23 (br, 12H), 1.33–1.25 (m, 18H) ppm; 31P NMR
(CDCl3, 161.9 MHz): d = 11.88 (JPt–P = 2,358.88 Hz),
8.57 (JPt–P = 2,320.03 Hz) ppm; 13C NMR (CDCl3,
100 MHz): d = 133.78, 133.33, 131.86, 131.83, 131.18,
131.14, 130.99, 131.33, 129.49, 129.15, 128.99, 128.55,
128.25, 128.17, 128.04, 127.16, 126.15, 125.51, 125.48,
124.45, 124.24, 123.17, 123.03, 117.81, 108.84, 108.70,
99.51, 95.26, 95.21, 90.34, 88.23, 88.09, 31.87, 29.64, 29.30,
22.64, 16.81, 16.63, 16.45, 16.41, 16.24, 8.39, 8.29 ppm.
1-[(3-Ethynylphenyl)ethynyl]pyrene (5, C26H14)
A 50-cm3 Schlenk flask was charged with 336 mg [2-(3-
bromophenyl)ethynyl]trimethylsilane (1.33 mmol), 77 mg
Pd(PPh3)4 (0.07 mmol), 13 mg CuI (0.07 mmol), 300 mg
1-ethynylpyrene (1.33 mmol), and 10 cm3 Et3N under
nitrogen atmosphere. The reaction mixture was stirred for
12 h at 70 °C, then insoluble materials were filtrated
through filter paper and the solvent was removed by
evaporation on a rotary evaporator. The residue was purified
by column chromatography on silica gel with PE/DCM
(20:1, v/v) as eluent to afford yellow solid trimethyl[[3-
(pyren-1-ylethynyl)phenyl]ethynyl]silane with a yield of
74 %. A mixture of 391 mg trimethyl[[3-(pyren-1-ylethy-
nyl)phenyl]ethynyl]silane (0.98 mmol) and 542 mg K2CO3
(3.93 mmol) in 10 cm3 THF and 10 cm3 MeOH was stirred
at room temperature for 2.0 h. The filtrate was evaporated
to give a dark yellow residue. The residue was purified by
column chromatography on silica gel with PE/DCM (10:1,
v/v) as eluent to afford yellow solid 5 with a yield of 92 %.
[[[3-[[Bis(triethylphosphine)][3-(pyren-1-ylethynyl)-
phenylethynyl]platinumethynyl]][5-(pyren-1-ylethynyl)]-
phenyl]ethynyl]bis(triethylphosphine)platinum
iodide (8, C78H85IP4Pt2)
Under an atmosphere of nitrogen, 2.7 mg CuI (0.01 mmol),
97 mg trans-Pt(PEt3)2I2 (0.14 mmol), and 79 mg compound
7 (0.07 mmol) were dissolved in 20 cm3 THF and 20 cm3 i-
Pr2NH. The reaction mixture was stirred at room temperature
for 2 h. The solvent was removed in vacuo and the residue
was purified via column chromatography with PE/DCM
(1:1, v/v) as eluent to afford a yellow solid of 8 with a yield of
1
70 %. Rf = 0.40 (PE/DCM, 1:1, v/v); m.p.: 105 °C; H
1
Rf = 0.41 (PE/DCM, 10:1, v/v); m.p.: 134 °C; H NMR
NMR (CDCl3, 400 MHz): d = 8.69–8.67 (d, J = 8.8 Hz,
2H), 8.25–8.02 (m, 16H), 7.63 (s, 1H), 7.51 (d, J = 8.8 Hz,
1H), 7.45 (s, 1H), 7.39 (s, 1H), 7.34–7.29 (m, 2H), 2.25 (br,
24H), 1.33-1.17 (m, 36H) ppm; 31P NMR (CDCl3,
(CDCl3, 400 MHz): d = 8.61 (d, J = 9.2 Hz, 1H),
8.20–7.98 (m, 8H), 7.89 (s, 1H), 7.71 (d, J = 7.6 Hz,
1H), 7.55 (d, J = 7.6 Hz, 1H), 7.39 (t, J = 7.6 Hz, 1H),
123

564
N.-W. Wu et al.
161.9 MHz):d = 11.59(JPt–P = 2367.14 Hz), 8.92(JPt–P
=
[[[3-[Bis(triethylphosphine)][[3-ethynyl-5-(pyren-1-yl-
2320.67 Hz) ppm; 13C NMR (CDCl3, 100 MHz): d =
133.78, 133.34, 131.87, 131.83, 131.18, 131.14, 130.99,
130.33, 129.50, 129.16, 128.99, 128.55, 128.26, 128.18,
128.04, 127.17, 126.16, 125.51, 125.49, 124.45, 124.24,
123.17, 123.03, 117.81, 108.84, 108.70, 99.51, 95.26, 95.21,
90.35, 88.28, 88.09, 16.64, 16.42, 8.39, 8.29 ppm.
ethynyl)phenyl]ethynyl]platinumethynyl][5-(pyren-1-yl-
ethynyl)]phenyl]ethynyl][[[3-[[bis(triethylphosphine)][3-(py-
ren-1-ylethynyl)phenylethynyl]platinumethynyl]][5-(pyren-1-
ylethynyl)]phenyl]ethynyl]bis(triethylphosphine)platinum
(13, C146H140P6Pt3)
Compound 13 was prepared from 4 and 10 by using the
similar procedure described for preparation of 7. Yellow
solid; yield 70 %; Rf = 0.40 (PE/DCM, 1:2, v/v); m.p.:
[[[[3-Ethynyl-5-(pyren-1-ylethynyl)]phenyl]ethynyl]]-
[[[3-[[bis(triethylphosphine)][3-(pyren-1-ylethynyl)-
phenylethynyl]platinumethynyl]][5-(pyren-1-ylethy-
nyl)]phenyl]ethynyl]bis(triethylphosphine)platinum
(10, C106H98P4Pt2)
1
147 °C; H NMR (CDCl3, 400 MHz): d = 8.71–8.64 (m,
4H), 8.21–8.02 (m, 32H), 7.65–7.31 (m, 13H), 3.15 (s, 1H),
2.26 (br, 36H), 1.31 (br, 48H) ppm; 31P NMR (CDCl3,
161.9 MHz): d = 11.90 (JPt–P = 2,374.91 Hz), 11.80
(JPt–P = 2374.91 Hz), 11.77 (JPt–P = 2,374.91 Hz) ppm;
13C NMR (CDCl3, 100 MHz): d = 134.23, 134.11, 133.80,
133.69, 131.88, 131.52, 131.31, 131.19, 131.11, 131.02,
130.69, 129.51, 129.20, 128.84, 128.32, 128.16, 128.03,
127.18, 126.16, 125.57, 125.50, 125.37, 124.45, 124.26,
123.62, 123.18, 122.86, 122.30, 117.95, 117.84, 117.41,
109.00, 108.86, 107.91, 95.46, 95.28, 94.21, 88.95, 88.29,
87.91, 83.02, 77.46, 16.41, 8.40 ppm; MALDI HRMS:
m/z calcd for C146H140P6Pt3 ([M?H]?) 2,664.83, found
2,664.49.
Compound 10 was prepared from 4 and 7 by using the
similar procedure described for preparation of 7. Yellow
solid; yield 85 %; Rf = 0.41 (PE/DCM, 1:1, v/v); 1H NMR
(CDCl3, 400 MHz): d = 8.70–8.64 (m, 3H), 8.23–8.02 (m,
24H), 7.62 (s, 2H), 7.58 (s, 1H), 7.50 (d, J = 7.2 Hz, 1H),
7.41 (br, 3H), 7.32 (m, 3H), 3.11 (s, 1H), 2.24 (br, 24H),
1.33–1.27 (m, 36H) ppm; 31P NMR (CDCl3, 161.9 MHz):
d = 11.60 (JPt–P = 2,368.60 Hz), 11.51 (JPt–P = 2,368.
60 Hz) ppm; 13C NMR (CDCl3, 100 MHz): d = 134.24,
134.11, 133.81, 133.68, 131.92, 131.88, 131.85, 131.53,
131.31, 131.20, 131.11, 131.02, 130.98, 129.51, 129.21,
128.84, 128.33, 128.19, 128.04, 127.18, 126.20, 126.16,
125.62, 125.58, 125.51, 125.38, 124.45, 124.27, 124.22,
123.62, 123.18, 122.87, 122.30, 117.95, 117.85, 117.41,
109.00, 108.80, 107.93, 95.45, 95.29, 94.21, 88.95, 88.28,
87.93, 83.03, 77.45, 31.89, 29.66, 29.32, 22.66, 16.42,
8.40 ppm; MALDI HRMS: m/z calcd for C106H98P4Pt2
([M?H]?) 1,885.59, found 1,885.53.
[[[3-[Bis(triethylphosphine)][[3-[iodide-
[bis(triethylphosphine)]platinum]ethynyl]-
[5-(pyren-1-ylethynyl)phenyl]ethynyl]platinumethynyl]-
[5-(pyren-1-ylethynyl)]phenyl]ethynyl][[[3-[[bis(triethyl-
phosphine)][3-(pyren-1-ylethynyl)phenylethynyl]-
platinumethynyl]][5-(pyren-1-ylethynyl)]phenyl]ethy-
nyl]bis(triethylphosphine)platinum (14, C158H169IP8Pt4)
Compound 14 was prepared from 13 by using the similar
procedure described for preparation of 8. Yellow solid;
yield 70 %; Rf = 0.45 (PE/DCM, 1:2, v/v); m.p.: 136 °C;
1H NMR (CDCl3, 400 MHz): d = 8.70 (d, J = 8.8 Hz,
4H), 8.25–8.02 (m, 32H), 7.63 (s, 1H), 7.50–7.39 (m, 9H),
[[3-[Iodide-[bis(triethylphosphine)]platinumethynyl]]-
[5-(pyren-1-ylethynyl)phenyl]ethynyl][[[3-[(triethyl-
phosphine)][3-(pyren-1-ylethynyl)phenylethynyl] platin-
umethynyl]][5-(pyren-1-ylethynyl)]phenyl]ethynyl]bis(tri-
ethylphosphine)platinum (11, C118H127IP6Pt3)
7.32 (br, 3H), 2.25 (br, 48H), 1.33–1.19 (m, 72H) ppm; 31
P
Compound 11 was prepared from 10 by using the similar
procedure described for preparation of 8. Yellow solid; yield
NMR (CDCl3, 161.9 MHz): d = 11.72 (JPt–P = 2,363.
90 Hz), 11.70 (JPt–P = 2,363.90 Hz), 9.06 (JPt–P = 2,321.
48 Hz) ppm; 13C NMR (CDCl3, 100 MHz): d = 133.82,
133.68, 133.35, 131.93, 131.26, 131.20, 131.16, 131.08,
130.71, 129.56, 128.84, 128.24, 128.19, 128.09, 127.24,
126.21, 125.64, 125.57, 125.54, 124.50, 124.33, 124.00,
123.47, 123.18, 123.03, 122.85, 118.03, 117.91, 115.92,
108.88, 95.31, 88.08, 16.63, 8.64, 8.32 ppm.
1
70 %; Rf = 0.43 (PE/DCM, 1:1, v/v); m.p.: 138 °C; H
NMR (CDCl3, 400 MHz): d = 8.70 (d, J = 9.2 Hz, 3H),
8.25–8.02 (m, 24H), 7.64 (s, 1H), 7.51–7.40 (m, 5H), 7.32
(br, 4H), 2.25 (br, 36H), 1.33–1.19 (m, 54H) ppm; 31P NMR
(CDCl3, 161.9 MHz): d = 11.56 (JPt–P = 2,365.84 Hz),
8.91 (JPt–P = 2,320.84 Hz) ppm; 13C NMR (CDCl3,
100 MHz): d = 134.24, 134.13, 133.82, 133.69, 131.92,
131.88, 131.85, 131.54, 131.31, 131.20, 131.17, 131.14,
131.11, 131.02, 130.98, 130.75, 129.53, 129.51, 129.22,
128.87, 128.79, 128.32, 128.19, 128.04, 127.18, 127.15,
126.20, 126.16, 125.62, 125.57, 125.51, 125.37, 124.45,
124.40, 124.27, 124.22, 123.63, 123.19, 122.89, 122.31,
117.95, 117.85, 117.41, 110.96, 109.02, 108.88, 108.81,
108.42, 108.09, 107.94, 95.46, 95.30, 94.21, 88.96, 88.30,
87.94, 83.04, 77.46, 16.44, 8.41 ppm.
[Bis[[[3-[[bis(triethylphosphine)][3-(pyren-1-ylethy-
nyl)phenylethynyl]platinumethynyl]][5-(pyren-1-
ylethynyl)]phenyl]ethynyl]]bis(triethylphosphine)platinum
(15, C144H140P6Pt3)
Under an atmosphere of nitrogen, 2.0 mg CuI (0.01 mmol),
55 mg compound 7 (0.05 mmol), and 83 mg 8 (0.05
mmol) were dissolved in 10 cm3 THF and 10 cm3 Et2NH.
The reaction mixture was stirred at room temperature for
123

Synthesis and characterization of multipyrene-modified platinum acetylide oligomers
565
1.5 h. The solvent was removed in vacuo and the residue
was purified via column chromatography with PE/DCM
(1:1, v/v) as eluent to afford a yellow solid of 15 in 73 %
yield. Rf = 0.40 (PE/DCM, 1:2, v/v); m.p.: 151 °C; 1H
NMR (CDCl3, 400 MHz): d = 8.70 (d, J = 9.2 Hz, 4H),
8.25–8.02 (m, 32H), 7.63 (s, 2H), 7.50 (d, J = 7.2 Hz, 3H),
7.41 (s, 4H), 7.32 (m, 6H), 2.25 (br, 36H), 1.30 (m, 54H)
MALDI HRMS: m/z calcd for C304H308P14Pt7 ([M?H]?)
5,760.88, found 5,767.65.
Acknowledgments We are grateful to the National Nature Science
Foundation of China (NSFC, nos. 91027005 and 20902027), Shang-
hai Shuguang Program (09SG25), Innovation Program of Shanghai
Municipal Education Commission (SMEC, 10ZZ32), Research Fund
for the Doctoral Program (RFDP, 20100076110004) of Higher Edu-
cation of China, the Program for New Century Excellent Talents in
University of Ministry of Education of China, and ‘‘the Fundamental
Research Funds for the Central Universities’’ for financial support.
ppm; 31P NMR (CDCl3, 161.9 MHz): d = 11.65 (JPt–P
=
2,362.77 Hz) ppm; 13C NMR (CDCl3, 100 MHz): d =
133.82, 133.69, 131.91, 131.89, 131.23, 131.18, 131.14,
131.06, 130.70, 129.55, 128.80, 128.23, 128.19, 128.08,
127.22, 126.19, 125.63, 125.55, 124.49, 124.31, 123.18,
122.85, 118.01, 117.89, 108.87, 95.30, 88.27, 16.44,
8.42 ppm; MALDI HRMS: m/z calcd for C144H140
P6Pt3 ([M?H]?) 2,640.83, found 2,640.50.
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Compound 16 was prepared from 11 and 10 by using the
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