Harvesting of organic triplet emissions in metal diynes and polyynes of group 10-12 transition elements containing the conjugation-interrupting diphenylfluorene unit

Article abstract of DOI:10.1021/ma049773o

Soluble and thermally stable group 10 platinum(II) and group 12 mercury(II) polyyne polymers containing the diphenylfluorene moiety trans-[-Pt(PBu ₃)₂C≡CRC≡C-]_n and [-HgC≡CRC≡ C-]_n (R = 9,9-diphenylfluorene) were prepared in good yields by polycondensation polymerization of trans[PtCl ₂(PBu₃)₂] or HgCl₂ with 9,9-bis(4-ethynylphenyl)fluorene. We report the optical absorption and photoluminescence spectra of these carbon-rich metal-based polymers and compare the results with their monomeric model complexes trans-[Pt(Ph)(PEt ₃)₂C≡CRC≡CPt(Ph)(PEt₃) ₂] and [MeHgC≡CRC≡CHgMe] as well as the group 11 gold(I) congener [(PPh₃)AuC≡CRC≡CAu(PPh₃)]. The regiochemical structures of the polymers were studied by NMR spectroscopy and by single-crystal X-ray analysis for the model platinum(II) compound. Our investigations indicate that harvesting of the organic triplet emissions can be achieved by the heavy-atom effect of group 10-12 transition metals (i.e., Pt, Au, Hg) which enables a very high efficiency of intersystem crossing from the S₁ singlet excited state to the T₁ triplet excited state. The influence of the metal and the fluorene ring on the intersystem crossing rate and the spatial extent of singlet and triplet excitons is characterized. These phosphorescent metal-organic materials show T₁-S₀ gaps of 2.5 eV or above, which correspond to S₁-S₀ gaps of 3.1 eV or higher. The present work indicates that high-energy triplet states (and concurrently high optical gaps) intrinsically lead to more efficient phosphorescence in metal-containing aryleneethynylenes and can facilitate the radiative decay pathway.

Full text of DOI:10.1021/ma049773o

4
496
Macromolecules 2004, 37, 4496-4504
Harvesting of Organic Triplet Emissions in Metal Diynes and Polyynes
of Group 10-12 Transition Elements Containing the
Conjugation-Interrupting Diphenylfluorene Unit
,
†
†
†
†
‡
Wa i-Yeu n g Won g,* Li Liu , Su k -Yu e P oon , Ka -Ho Ch oi, Kok -Wa i Ch ea h , a n d
J ia n -Xin Sh i†
,§
Departments of Chemistry and Physics and Centre for Advanced Luminescence Materials,
Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, P.R. China, and
Department of Chemistry, Zhongshan University, Guangzhou 510275, P.R. China
Received February 3, 2004; Revised Manuscript Received April 14, 2004
ABSTRACT: Soluble and thermally stable group 10 platinum(II) and group 12 mercury(II) polyyne
polymers containing the diphenylfluorene moiety trans-[-Pt(PBu
C-] (R ) 9,9-diphenylfluorene) were prepared in good yields by polycondensation polymerization of trans-
PtCl (PBu ] or HgCl with 9,9-bis(4-ethynylphenyl)fluorene. We report the optical absorption and
photoluminescence spectra of these carbon-rich metal-based polymers and compare the results with their
monomeric model complexes trans-[Pt(Ph)(PEt CtCRCtCPt(Ph)(PEt ] and [MeHgCtCRCtCHgMe]
as well as the group 11 gold(I) congener [(PPh )AuCtCRCtCAu(PPh )]. The regiochemical structures of
3
)
2
CtCRCtC-]
n
and [-HgCtCRCt
n
[
2
3
)
2
2
3
)
2
3 2
)
3
3
the polymers were studied by NMR spectroscopy and by single-crystal X-ray analysis for the model
platinum(II) compound. Our investigations indicate that harvesting of the organic triplet emissions can
be achieved by the heavy-atom effect of group 10-12 transition metals (i.e., Pt, Au, Hg) which enables
a very high efficiency of intersystem crossing from the S singlet excited state to the T triplet excited
1 1
state. The influence of the metal and the fluorene ring on the intersystem crossing rate and the spatial
extent of singlet and triplet excitons is characterized. These phosphorescent metal-organic materials
show T
1
-S
0
gaps of 2.5 eV or above, which correspond to S
1
0
-S gaps of 3.1 eV or higher. The present
work indicates that high-energy triplet states (and concurrently high optical gaps) intrinsically lead to
more efficient phosphorescence in metal-containing aryleneethynylenes and can facilitate the radiative
decay pathway.
In tr od u ction
relative positions of singlet and triplet states strongly
influence the intersystem crossing into the triplet
manifold. For organic systems, this provides a major
nonradiative decay mechanism and reduces the lumi-
nescence efficiency. The intersystem crossing rate de-
pends exponentially on the energy gap to the nearest
The search for new organic and metal-organic mo-
lecular functional materials with optoelectronic applica-
tions continues to attract much current attention.
particular, conjugated ethynylated materials, such as
arylacetylenes,
1
-4
In
1
-4
5,6
poly(aryleneethynylenes)s,
and
2
5
7
,8
triplet excited state. It would be very useful to
understand the factors that control the spatial extent
of the singlet and triplet energy levels for the chemical
tailoring of the singlet-triplet gap. To study the triplet
excited states in conjugated polymers directly, we and
others have used suitable model systems where the
triplet excited state has been made emissive, thus
rendering it easily probed by conventional optical
metal-containing acetylide complexes and polymers,
have been extensively studied in this context. Intensive
studies of conjugated polymers over the past decade
have made it possible to clarify some fundamental issues
9
-11
about the nature of the singlet excited states,
yet
still relatively little is known about the nature of triplet
excited states in conjugated polymers. Much of the
recent work has shown that triplet states play an
important role in optical and electrical processes within
conjugated polymers with direct implications for their
2
5-33
spectroscopy.
This is achieved by incorporation of
platinum atom within the conjugated backbone in which
strong spin-orbit coupling associated with such heavy
metal renders the spin-forbidden triplet emission (phos-
phorescence) partially allowed. Similar research work
has recently been extended to their closest neighbors,
technological exploitation.1
2-19
It has been demonstrated
that the ultimate efficiency of light-emitting diodes
(
LEDs) is controlled by the fraction of triplet states
2
0-24
generated or harvested.
Therefore, a thorough
3
4-36
37
viz. gold(I)
and mercury(II).
understanding of triplet photophysics is essential if one
intends to develop a full picture of basic excitations in
conjugated polymers.
Recently, there has been increasing experimental and
theoretical attention focusing on the energy levels of
singlet and triplet states in conjugated polymers. The
A number of literature reports have shown that the
nonradiative decay of the triplet states in a series of
Pt-containing conjugated polymers and monomers may
be quantitatively described by the energy gap law.25 In
other words, work should focus on polymers with high-
energy triplets (and concurrently high optical gaps) to
avoid competition with nonradiative decay. One promis-
ing approach of designing molecular systems with high
HOMO-LUMO gap is based on an interruption of the
conjugation by incorporating nonconjugated segments
into the polymer main chain. It is known that the
diphenylfluorene unit containing two aromatic rings in
†
Department of Chemistry and Centre for Advanced Lumines-
cence Materials, Hong Kong Baptist University.
‡
Department of Physics and Centre for Advanced Luminescence
Materials, Hong Kong Baptist University.
§
Zhongshan University.
*
Corresponding author: Fax +852-3411-7348; e-mail rwywong@
hkbu.edu.hk.
1
0.1021/ma049773o CCC: $27.50 © 2004 American Chemical Society
Published on Web 05/21/2004

Macromolecules, Vol. 37, No. 12, 2004
Metal Diynes and Polyynes 4497
the cardo group can be introduced in some organic
copolymers as a tetrahedral conjugation-breaking unit
125.26, 119.99 (Ar), 108.45, 77.20 (CtC), 65.14 (quat C), 26.27,
4.34, 23.69, 13.81 (Bu). 31P { H} NMR (CDCl
1
): δ (ppm) 3.90
2
(
3
1
J
P-Pt ) 2361 Hz). GPC (THF as eluent): M
w
) 45 700, M )
n
to improve the thermal stability and solubility of the
materials.3
8-40
68 2 n
43 410, polydispersity ) 1.05. Anal. Calcd for (C53H P Pt) :
C, 66.16; H, 7.12. Found: C, 66.02; H, 7.05.
In this connection, we report here the
first examples of group 10-12 metal-acetylide com-
plexes and polymers containing the conjugation-inter-
rupting diphenylfluorene unit so that we can evaluate
[
P t-T(DP F )T]
1
. A solution of [H-T(DPF)T]
] (108.8 mg, 0.20
(16 mL, 1:1, v/v) was charged into a
00 mL Schlenk flask, and a small amount of CuI (3 mg) was
1
(36.6 mg, 0.10
mmol) and 2 equiv of trans-[PtCl(Ph)(PEt )
mmol) in Pr NH/CH Cl
2 2 2
3 2
i
3
how the sp -carbon atom of fluorene would limit the
1
effective conjugation length of such conjugated system,
and hence, the resulting optoelectronic properties can
be controlled and optimized.
then added. The resulting mixture was stirred at room
temperature over a period of 15 h, after which all the volatile
components were evaporated to dryness. The residue was
redissolved in CH
preparative TLC plates eluting with hexane/CH
) 0.55) to give the title complex as an off-white crystalline
solid in an isolated yield of 69% (95.3 mg). IR (CH Cl ): ν(Ct
2
Cl
2
, and the solution was purified on
2
2
Cl (3:2, v/v,
Exp er im en ta l Section
R
f
Gen er a l. All reactions were carried out under a nitrogen
atmosphere with the use of standard Schlenk techniques, but
no special precautions were taken to exclude oxygen during
workup. Solvents were predried and distilled from appropriate
drying agents. All reagents and chemicals, unless otherwise
stated, were purchased from commercial sources and used
without further purification. Preparative TLC was performed
on 0.7 mm silica plates (Merck Kieselgel 60 GF254) prepared
2
2
-
1
1
C) 2098 cm
. H NMR (CDCl ): δ (ppm) 7.75 (m, 2H, Ar),
3
7.39-7.22 (m, 10H, Ar + H
Ar), 6.95 (t, J ) 7.6 Hz, 4H, H
ortho
of Ph-Pt), 7.14-7.02 (m, 8H,
meta
of Ph-Pt), 6.79 (t, J ) 7.6
Hz, 2H, H
para
of Ph-Pt), 1.72 (m, 24H, CH CH ), 1.06 (m, 36H,
2
3
1
3
CH CH ). C NMR (CDCl ): δ (ppm) 151.46, 150.18, 146.01,
2
3
3
141.93, 140.03, 139.15, 131.86, 130.52, 127.69, 127.20, 126.18,
125.97, 121.55, 121.11, 120.27, 119.97, 112.96, 109.72 (Ar),
4
1
31
1
in our laboratory. The compounds trans-[PtCl(Ph)(PEt
3
)
m
2
],
Ct
CtC-
104.74, 94.41 (CtC), 65.14 (quat C), 15.00, 7.97 (Et). P { H}
4
2
1
trans-[PtCl
2
(PBu
3
)
2
], trans-[Pt(Ph)(PEt
3
)
2
CtC(p-C
6
H
4
)
NMR (CDCl ): δ (ppm) 10.96 ( J
P-Pt
) 2628 Hz). FAB-MS (m/
3
+
CPt(Ph)(PEt
3
)
2
], and trans-[-Pt(PBu
3
)
2
CtC(p-C
6
H
4
)
m
z): 1381 [M ]. Anal. Calcd for C H P Pt : C, 56.51; H, 6.27.
6
5
86
4
2
4
3-45
]
n
(m ) 1, 2)
were prepared by literature methods. Infrared
Cl solutions using a Perkin-
Found: C, 56.34; H, 6.08.
spectra were recorded as CH
2
2
[Hg-T(DP F )T] . A solution of HgCl (135.8 mg, 0.50 mmol)
∞
2
Elmer Paragon 1000 PC or a Nicolet Magna 550 Series II FTIR
spectrometer. NMR spectra were measured in appropriate
solvents on a J EOL EX270 or a Varian Inova 400 MHz FT-
in MeOH (10 mL) was mixed with [H-T(DPF)T] (183.2 mg,
1
0.50 mmol) in MeOH (10 mL). To this mixture, 12.5 mL of
0.20 M basic MeOH (2.50 mmol, prepared by dissolving 0.40
g of NaOH in 50 mL of MeOH) was added. Within several
minutes, an off-white solid precipitated from the homogeneous
solution. The reaction was complete after stirring for 12 h, and
the solid was collected by filtration, washed with MeOH (2 ×
20 mL), and air-dried to furnish the polymer in 80% yield
1
13
NMR spectrometer, with H and C NMR chemical shifts
3
1
quoted relative to TMS and P chemical shifts relative to an
5% H PO external standard. Fast atom bombardment (FAB)
8
3
4
mass spectra were recorded on a Finnigan MAT SSQ710 mass
spectrometer. Electronic absorption spectra were obtained with
a HP 8453 UV-vis spectrometer. For solid-state emission
spectral measurements, the 325 nm line of a He-Cd laser was
used as an excitation source. The luminescence spectra were
analyzed by a 0.25 m focal length double monochromator with
a Peltier cooled photomultiplier tube and processed with a lock-
in-amplifier. For the low-temperature experiments, samples
were mounted in a closed-cycle cryostat (Oxford CC1104) in
which the temperature can be adjusted from 10 to 330 K. The
solution emission spectra were measured on a PTI Fluores-
cence Master Series QM1 spectrophotometer. The fluorescence
quantum yields were determined in toluene solutions at 290
K against the anthracene standard (Φ ) 0.27). Phosphores-
cence quantum yields were measured in solid thin films at 20
-
1
1
(226.0 mg). IR (CH Cl ): ν(CtC) 2146 cm
2
2
.
H NMR
(CDCl ): δ (ppm) 7.77 (d, J ) 7.6 Hz, 2H, Ar), 7.37-7.27 (m,
3
10H, Ar), 7.14-7.11 (m, 4H, Ar). 13C NMR (CDCl ): δ (ppm)
3
150.45, 146.66, 146.50, 140.44, 132.70, 132.49, 128.40, 128.29,
126.39, 121.06, 120.89, 120.62 (Ar), 105.80, 94.38 (CtC), 65.56
(quat C). GPC (THF as eluent): Mw ) 8900, Mn ) 8590,
polydispersity ) 1.04. Anal. Calcd for (C H Hg) : C, 61.65;
2
9
16
n
H, 2.85. Found: C, 61.48; H, 2.75.
[Hg-T(DP F )T] . The organic diyne [H-T(DPF)T] (36.6
1
1
mg, 0.10 mmol) in MeOH (10 mL) was first combined with
MeHgCl (50.2 mg, 0.20 mmol) in MeOH (10 mL). 0.20 M basic
MeOH (2.5 mL, 0.50 mmol) was subsequently added to produce
a pale yellow suspension. The solvent was then decanted, and
the light yellow solid (68.4 mg, 86%) was washed with MeOH
K relative to the prototypical polymer trans-[-Pt(PBu
3 2
) Ct
C(p-C )CtC-] (Φ ) 0.30 at 20 K). The molecular weights
6
H
4
n
P
(2 × 10 mL) and air-dried. IR (CH Cl ): ν(CtC) 2137 cm-1
.
2
2
of the polymers were determined by GPC (HP 1050 Series
HPLC with visible wavelength and fluorescent detectors) using
polystyrene standards, and thermal analyses were performed
with a Perkin-Elmer Pyris Diamond DSC and Perkin-Elmer
DTA-7 thermal analyzers.
1
H NMR (CDCl ): δ (ppm) 7.75 (d, J ) 8.1 Hz, 2H, Ar), 7.38-
3
2
7.26 (m, 10H, Ar), 7.10 (d, J ) 8.1 Hz, 4H, Ar), 0.66 (s, J
Hg-H
) 146 Hz, 6H, CH ). 13C NMR (CDCl ): δ (ppm) 150.23, 145.42,
3
3
142.80, 140.01, 131.95, 127.92, 127.75, 127.62, 125.97, 121.54,
120.20 (Ar), 104.92, 92.26 (CtC), 65.25 (quat C), 7.19 (CH ).
3
[
P t-T(DP F )T]
∞
. A mixture of 9,9-bis(4-ethynylphenyl)-
(75.0 mg, 0.20 mmol), and trans-
] (134.1 mg, 0.20 mmol) in a 1:1 molar ratio in
Cl (50 mL, 1:1, v/v) was allowed to react in the
Anal. Calcd for C31
H, 2.59.
[Au -T(DP F )T]
H
22Hg
2
: C, 46.79; H, 2.79. Found: C, 46.55;
fluorene, [H-T(DPF)T]
PtCl
1
[
2
(PBu
3
)
2
1
. To the solution of [H-T(DPF)T] (33.0 mg,
1
i
Pr
2
NH/CH
2
2
0.09 mmol) in MeOH (10 mL) was added 2 mol equiv of Au-
presence of CuI (3 mg). The solution was stirred at room
temperature for 15 h, after which all volatile components were
removed under reduced pressure. The residue was taken up
in CH Cl and filtered through a silica gel column using the
2 2
same solvent as the eluent to give a yellow solution. Upon
removal of solvent, the product was then reprecipitated twice
3
(PPh )Cl (89.0 mg, 0.18 mmol), followed by NaOMe/MeOH
(0.20 M, 0.45 mmol). The mixture was stirred at room
temperature overnight, and the pale yellow powdery solid was
then collected by decantation which was washed with MeOH
(2 × 10 mL) and air-dried to give 109.7 mg (95%) of the pure
-
1 1
product. IR (CH
2
Cl
2
): ν(CtC) 2113 cm . H NMR (CDCl ): δ
3
from a CH
2
Cl
2
/MeOH mixture followed by washing with MeOH
(ppm) 7.73 (d, J ) 7.3 Hz, 2H, Ar), 7.57-7.30 (m, 40H, Ar),
to afford a light yellow powder in 69% yield (132.8 mg). IR
7.05 (d, J ) 8.4 Hz, 4H, Ar). 13C NMR (CDCl
3
): δ (ppm) 150.73,
-
1 1
(
(
2
CH
d, J ) 7.6 Hz, 2H, Ar), 7.38 (d, J ) 7.2 Hz, 2H, Ar), 7.32 (m,
H, Ar), 7.23 (m, 2H, Ar), 7.17 (m, 2H, Ar), 7.09 (d, J ) 7.6
Hz, 4H, Ar), 7.00 (d, J ) 8.4 Hz, 2H, Ar), 2.07 (m, 12H, PCH ),
.53 (m, 12H, PCH CH ), 1.39 (m, 12H, P(CH CH CH ), 0.87
). C NMR (CDCl ): δ (ppm) 151.28, 142.25,
40.06, 130.46, 128.99, 128.19, 127.67, 127.50, 127.20, 126.20,
2
Cl
2
): ν(CtC) 2101 cm . H NMR (CDCl
3
): δ (ppm) 7.73
144.15, 139.95, 134.24, 134.03, 132.03, 131.39, 131.31, 130.04,
129.22, 129.05, 128.88, 127.65, 127.55, 127.29, 126.14, 123.06,
119.95 (Ar), 103.69, 77.21 (CtC), 65.22 (quat C). 31P { H} NMR
1
2
(CDCl
3
46 2 2
): δ (ppm) 43.69. Anal. Calcd for C65H P Au : C, 60.85;
1
(
1
2
2
2
)
2
2
3
H, 3.61. Found: C, 60.62; H, 3.45.
1
3
m, 18H, CH
3
3
X-r a y Cr ysta llogr a p h y. Colorless crystals of [Pt-T(D-
PF)T] suitable for X-ray diffraction studies were grown by slow
1

4
498 Wong et al.
Macromolecules, Vol. 37, No. 12, 2004
Sch em e 1. Syn th esis of 9,9-Bis(4-eth yn ylp h en yl)flu or en ea
a
i
Reagents and conditions: (i) NaNO
2
/HBr, CuBr; (ii) trimethylsilylacetylene, Pd(OAc)
2
, PPh
3
, CuI, Pr
2
2 3
NH, 75 °C; (iii) K CO ,
MeOH, rt.
Sch em e 2. Syn th esis of Dip h en ylflu or en e-Ba sed Meta l Alk yn ylsa
a
i
i
Reagents and conditions: (i) trans-[PtPh(Cl)(PEt
3
)
2
] (2 equiv), CuI, Pr
2
NH, rt; (ii) trans-[PtCl
2
(PBu
3
)
2
] (1 equiv), CuI, Pr
2
NH,
rt; (iii) Au(PPh
3 2
)Cl (2 equiv), NaOH/MeOH, rt; (iv) MeHgCl (2 equiv), NaOH/MeOH, rt; (v) HgCl (2 equiv), NaOH/MeOH, rt.
evaporation of its solution in a CH
2
Cl
2
/hexane mixture at room
reaction sequence followed by the proto-desilylation with
temperature. Geometric and intensity data were collected
using graphite-monochromated Mo KR radiation (λ ) 0.710 73
Å) on a Bruker Axs SMART 1000 CCD area detector. The
K2CO3 in MeOH to afford the diethynyl organic precur-
26-33
sor [H-T(DPF)T]1 in overall good yield.
Scheme 2
shows the chemical structure and the synthetic strate-
gies to the polymers and their model complexes in the
present study. The triple bonds are abbreviated by T
and the diphenylfluorene ring by DPF. Model monomer
complexes and polymers are differentiated by use of the
subscripts 1 and ∞, respectively. The organic ligand
4
6
collected frames were processed with the software SAINT,
and an absorption correction was applied (SADABS)47 to the
collected reflections. The structure was solved by direct
4
8
methods (SHELXTL) in conjunction with standard difference
Fourier techniques and subsequently refined by full-matrix
2
least-squares analyses on F . All non-hydrogen atoms were
assigned with anisotropic displacement parameters. Crystal
[
H-T(DPF)T]1 can serve as a versatile synthon to form
data: C65
H
86
P
4
Pt
2
1
, M ) 1381.40, monoclinic, space group P2 /
a series of group 10-12 metal-acetylide complexes and
polymers by adaptation of the dehydrohalogenation
procedures reported in the literature.
n, a ) 8.9602(3), b ) 17.6088(6), c ) 42.253(2) Å, â ) 91.999-
3
(
1)°, U ) 6662.6(4) Å , Z ) 4, T ) 293 K, µ(Mo KR) ) 4.325
2
6-33
-
1
The feed mole
mm , 33 055 reflections measured, 11 722 unique, Rint
.0405, final R
)
0
1
) 0.0464, wR
2
) 0.1169 for 8235 [I > 2σ(I)]
ratios of the platinum chloride precursors and the
diethynyl ligand were 2:1 and 1:1 for the monomer and
polymer syntheses, respectively, and each product was
carefully purified to remove ionic impurities and cata-
lyst residues. The monomer [Pt-T(DPF)T]1 was isolated
by preparative TLC on silica. Purification of the polymer
[Pt-T(DPF)T]∞ was accomplished by silica column
chromatography using CH2Cl2 as the eluent, and it was
obtained in high purity. Mercuration of [H-T(DPF)T]1
with a stoichiometric quantity of HgCl2 using methan-
observed reflections (CCDC deposition number 235990).
Resu lts a n d Discu ssion
Syn th esis. The synthesis of 9,9-bis(4-ethynylphenyl)-
fluorene, [H-T(DPF)T]1, is outlined in Scheme 1. The
compound 9,9-bis(4-bromophenyl)fluorene was prepared
from the corresponding commercially available diamine
by a classical Sandmayer procedure,39 which then
reacted with Me3SiCtCH via the Sonogashira coupling

Macromolecules, Vol. 37, No. 12, 2004
Metal Diynes and Polyynes 4499
F igu r e 1. A perspective drawing of [Pt-T(DPF)T]
have been omitted for clarity.
1
with the ellipsoids shown at the 25% probability level. All hydrogen atoms
Ta ble 1. Str u ctu r a l a n d Th er m a l P r op er ties of th e
P olym er s
reference standard. However, the absence of end-group
NMR resonances is suggestive of their high molecular
weight. We found that both polymers can cast tough,
free-standing thin films of good quality from appropriate
solvents for optical characterization.
polymer
Mw
Mn
Mw/Mn
Tdecomp(onset) (°C)
[
[
Pt-T(DPF)T]∞
Hg-T(DPF)T]∞
45700 43410
8900 8590
1.05
1.04
347 ( 5
292 ( 5
Ch em ica l Ch a r a cter iza tion . The good solubilities
olic NaOH at room temperature gave an off-white solid
identified as [Hg-T(DPF)T]∞.37 Complex [Hg-T(D-
PF)T]1, as a model complex of [Hg-T(DPF)T]∞, was also
synthesized by treatment of [H-T(DPF)T]1 with 2 equiv
of MeHgCl, in which one coordination site is protected
of our new compounds render them amenable to spec-
1
13
31
troscopic studies. The IR, NMR ( H, C and P), MS,
and elemental analysis data shown in the Experimental
Section are in line with their chemical structures. The
solution IR spectra are each characterized by a single
4
9,50
by a Me group, under similar basic conditions.
-
1
Likewise, we have also prepared the d10 digold(I)
sharp ν(CtC) absorption band at ca. 2098-2146 cm
.
The insoluble component of [Hg-T(DPF)T]∞ also exhib-
its a characteristic solid-state IR ν(CtC) band, similar
diacetylide counterpart [Au-T(DPF)T]1, an isoelectronic
and isolobal analogue of [Hg-T(DPF)T]1, by reaction of
3
1
1
to that for the soluble portion. The single P { H} NMR
signals flanked by platinum satellites for [Pt-T(D-
PF)T]∞ and [Pt-T(DPF)T]1 are consistent with a trans
Au(PPh3)Cl with [H-T(DPF)T]1 in a mole ratio of 2:1
in the presence of a base.51 The yields of these trans-
formations are high in each case. All the new complexes
and polymers are air-stable and can be stored without
any special precautions. They generally exhibit good
solubility in chlorocarbons such as CH2Cl2 and CHCl3
but are insoluble in hydrocarbons. However, we note
that only the lower molecular weight fraction of [Hg-
T(DPF)T]∞ can readily dissolve in chlorinated solvents,
and there is always some insoluble portion left in the
solution (presumably consisting of polymer chains of
very high molecular weights) which requires filtration
prior to characterization. Estimates of the molecular
weights using gel permeation chromatography (GPC) in
THF indicate that the degree of polymerization calcu-
lated from Mn are 46 and 16 for [Pt-T(DPF)T]∞ and
1
geometry of the square-planar Pt unit. The J P-Pt values
in [Pt-T(DPF)T]∞ and [Pt-T(DPF)T]1 are typical of
5
2-54
those for related trans-PtP2 systems.
The formulas
of the model complexes [Pt-T(DPF)T]1, [Hg-T(DPF)T]1,
and [Au-T(DPF)T]1 were successfully established by
the presence of intense molecular ion peaks in their
respective positive FAB mass spectra. NMR analyses
clearly indicate that a well-defined and symmetrical
structure has been obtained for each compound. In all
1
cases, H NMR resonances arising from the protons of
the organic moieties were observed. Notably, two dis-
1
3
tinct C NMR signals for the R- and â-acetylenic carbon
atoms were observed, and the R-acetylide chemical
shifts are shifted downfield with respect to the free
dialkyne, in agreement with the formation of metal-
C(sp) σ-bond. The aromatic region of their 13C NMR
spectra also gives more precise information about the
regiochemical structure of the main-chain skeleton and
reveals a high degree of structural regularity in the
polymers. For instance, only 18 well-defined peaks
appear in the aromatic region, related to the 36 aromatic
carbon atoms of the symmetric diplatinum structure for
[Pt-T(DPF)T]1. In each case, the carbon resonances due
to the butyl or ethyl groups are clearly identified, and
[Hg-T(DPF)T]∞ (soluble portion), respectively (Table 1).
The GPC values should be used with great care, and
the GPC method does not give absolute values of
molecular weights but provides a measure of hydrody-
namic volume. Rodlike polymers in solution possess
different hydrodynamic properties than flexible poly-
mers. So, calibration of the GPC with polystyrene
standards might overestimate the values of the molec-
ular weights of the polyynes to some extent. Similar
molecular weight distributions have been observed for
other reported platinum(II) polyynes based on the same

4
500 Wong et al.
Macromolecules, Vol. 37, No. 12, 2004
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles (d eg) for
P t-T(DP F )T]1
shows that they exhibit good thermal stability. Decom-
position commences at 347 and 292 °C for [Pt-T(D-
PF)T]∞ and [Hg-T(DPF)T]∞, respectively, and decom-
position onset was defined as a mass loss of 2%. The
onset temperature for the former is comparable to those
for the dialkylfluorene-substituted platinum polyynes
but is higher than those in related polymers trans-
[
Pt(1)-P(1)
Pt(2)-P(3)
Pt(1)-C(19)
C(19)-C(20)
C(24)-C(27)
2.2811(16) Pt(1)-P(2)
2.2886(16)
2.3065(18)
2.009(5)
2.266(2)
2.013(5)
1.199(7)
1.546(6)
Pt(2)-P(4)
Pt(2)-C(47)
C(46)-C(47)
C(27)-C(40)
1.211(7)
1.528(6)
P(1)-Pt(1)-P(2)
177.68(6) P(1)-Pt(1)-C(19) 87.45(15)
[
-Pt(PBu3)2CtCRCtC-]n (R ) phenylene, thienylene,
P(2)-Pt(1)-C(19) 90.91(15) P(3)-Pt(2)-P(4)
175.11(9)
27,33
P(3)-Pt(2)-C(47) 87.4(2)
Pt(1)-C(19)-C(20) 177.8(5)
Pt(2)-C(47)-C(46) 178.0(7)
C(24)-C(27)-C(40) 112.7(3)
P(4)-Pt(2)-C(47) 91.7(2)
C(19)-C(20)-C(21) 174.9(6)
C(43)-C(46)-C(47) 176.7(7)
pyridyl)
]
and trans-[-Pt(PBu3)2CtC(p-C6H4)2CtC-
n
(296 °C). The onset of decomposition for [Hg-
T(DPF)T]∞ takes place at a higher temperature than
those for [-HgCtCRCtC-]n (R ) dialkylfluorene)
3
7
(200-280 °C). Introduction of the diphenylfluorene
the characteristic peak at about 65.0 ppm corresponds
3
group with its unique cardo structure has the added
effect of enhancing the thermal stability of this class of
metal polyynes. We observe a sharp weight loss of 35%
between 347 and 430 °C for [Pt-T(DPF)T]∞ whereas
to the sp -carbon atom of the fluorene ring. Similarly,
the 13C NMR spectral features of [Pt-T(DPF)T]∞ and
[
Hg-T(DPF)T]∞ agree with the polymer structures
shown. The three-dimensional molecular structure of
Pt-T(DPF)T]1, as confirmed by X-ray crystallography,
3
2% of the weight was lost for [Hg-T(DPF)T]∞ as the
[
temperature rose from 292 to 400 °C. The decomposition
step is ascribed to the removal of six butyl groups from
also helped to establish polymer structure in the solid
state (Figure 1). Pertinent bond distances and angles
are given in Table 2. The coordination geometry at each
Pt center is square-planar with the two PEt3 groups
trans to each other, and the metal capping groups are
connected by the 9,9-bis(4-phenylethynyl)fluorene ligand.
To our knowledge, this is the first structurally charac-
terized example of a diphenylfluorene-linked metal
σ-alkynyl complex. The CtC bond length [average
[Pt-T(DPF)T]∞ and the loss of two phenyl plus one Ct
C groups from [Hg-T(DPF)T]∞. Both polymers did not
display discernible glass transition in the DSC curves.
The polymer [Pt-T(DPF)T]∞ exhibits a minor endot-
herm coincident with mass loss due to decomposition.
On the contrary, an exothermic peak was present at ca.
3
50 °C for [Hg-T(DPF)T]∞, and such a transition
releases ca. 88.4 J /g of energy. Both polymer samples
decompose without melting.
1
.205(7) Å] is characteristic of metal-alkynyl σ-bonding.
The central fluorene ring is essentially planar which
makes dihedral angles of 107° and 81° with the C(21)-
and C(40)-phenyl planes. The sp -hybridized carbon
Op t ica l Ab sor p t ion a n d P h ot olu m in escen ce
Sp ectr oscop y. The photophysical data of the new
compounds are shown in Table 3. All the metal alkynyls
in the present study display similar structured absorp-
tion bands in the near-UV region. The lowest energy
transitions are predominantly intraligand in nature and
3
atom C(27) was shown to adopt a tetrahedral geometry.
The bond angles of 177.8(5)° and 178.0(7)° for the two
Pt-CtC units conform to the rigid-rod nature of this
monomer.
Th er m a l An a lysis. The thermal properties of the
polymers were examined by thermal gravimetry (TG)
and differential scanning calorimetry (DSC) under
nitrogen (Table 1). Analysis of the TG trace (heating
rate 20 °C/min) for [Pt-T(DPF)T]∞ and [Hg-T(DPF)T]∞
1
exhibit both acetylenic and aromatic (ππ*) character,
possibly mixed with some admixture of metal orbitals.
The 0-0 absorption peak is assigned as the S0 f S1
transition from the highest occupied molecular orbital
(HOMO) to the lowest unoccupied molecular orbital
Ta ble 3. P h otop h ysica l Da ta for th e Mon om er s a n d P olym er s
λmax (nm)
CH2Cl2a
λem (nm)e
film (11 K)
film
Eg (eV)b
CH2Cl2 (290 K)c
film (290 K)
frozen CH2Cl2 (77 K)d
[
Pt-T(DPF)T]1
Pt-T(DPF)T]∞
263 (11.2)
270
291
326
3.60
367
384*
(0.022)
450
514*
555*
451
473*
483*
451 (29.4 ( 0.4)
472*
2
3
91 (8.7)
21 (7.8)
501*
4
96*
[
267
270
290
332br
3.38
369
459
512*
547*
458
455 (24.6 ( 0.6)
486*
501*
542*
2
3
3
91
31
42
419*
456*
509*
478*
490*
505*
(
0.003)
[
Hg-T(DPF)T]1
Hg-T(DPF)T]∞
267 (4.2)
274
288
312
263
278
298
312
279
293
307
3.82
3.80
386
490 br
470 br
494 br
462 (11.9 ( 1.9)
465 (35.7 ( 2.8)
2
3
80 (3.7)
09 (0.5)
(0.013)
[
260
374*
390
(0.005)
473
498
523*
2
2
3
75
89
09
[
Au-T(DPF)T]1
262 (4.0)
3.76
3.92
369*
390
413*
(0.007)
479
499*
533*
454*
482
499
532*
452
470*
2
2
3
75 (4.9)
87 (4.8)
00 (4.8)
485 (48.1 ( 2.4)
500*
5
25*
[
H-T(DPF)T]1
257 (3.3)
253
298
311
379
(0.22)
2
3
97 (0.07)
09 (0.16)
a
Extinction coefficients are shown in parentheses. b Estimated from the onset wavelength of the solid-state optical absorption.
c
d
Fluorescence quantum yields shown in parentheses are measured in toluene relative to anthracene. Phosphorescence lifetimes (µs) at
7 K for the peak maxima are shown in parentheses. Asterisks indicate emission peaks appear as shoulders or weak bands. br ) broad.
e
7

Macromolecules, Vol. 37, No. 12, 2004
LUMO), which are mainly delocalized π and π* orbitals.
Metal Diynes and Polyynes 4501
(
Coordination of each of the metal entities to the organic
system results in enhanced π f π* transitions for the
aryleneethynylene moiety. As compared to the band at
3
09 nm in CH2Cl2 for [H-T(DPF)T]1, we find that the
position of the lowest energy absorption band is red-
shifted after the inclusion of platinum fragment in [Pt-
T(DPF)T]1 and [Pt-T(DPF)T]∞. This reveals that π
conjugation is preserved through the Pt site by mixing
of the frontier orbitals of Pt and the ligand.55 However,
the absence of marked bathochromic shift in the lowest
energy absorption peak for the corresponding Au(I) and
Hg(II) compounds is indicative of little metal through-
bond conjugation in these cases. The transition energies
of the polymer [Pt-T(DPF)T]∞ are lowered with respect
to those of the monomer [Pt-T(DPF)T]1, suggesting a
well-extended singlet excited state in the Pt(II) polymer.
The apparent lack of an energy shift in the S0-S1
transition between [Hg-T(DPF)T]1 and [Hg-T(DPF)T]∞
shows that the lowest singlet excited state is confined
to a single repeat unit, which is in contrast to their
platinum(II) congeners. In energy terms, the experi-
mentally determined HOMO-LUMO energy gaps (Eg)
as measured from the onset wavelength in solid film
state are also tabulated in Table 3. According to the
nature of the metal groups, the optical energy gaps of
the polyynes follow the experimental order [Hg-T(D-
PF)T]∞ > [Pt-T(DPF)T]∞ and those of the monomers
F igu r e 2. Room temperature optical absorption spectrum and
the photoluminescence (PL) spectrum (11 K) of [Pt-T(DPF)T]
in solid.
∞
[Hg-T(DPF)T]1 > [Au-T(DPF)T]1 > [Pt-T(DPF)T]1.
With reference to other similar bi(p-phenylene)-linked
compounds [(Cy3P)AuCtC(p-C6H4)2CtCAu(PCy3)] (323
nm),3 trans-[Pt(Ph)(PEt3)2CtC(p-C6H4)2CtCPt(Ph)-
4
(PEt3)2](349 nm),and trans-[-Pt(PBu3)2CtC(p-C6H4)2Ct
C-]n (372 nm), we note that the presence of the non-
π-conjugated diphenylfluorene unit hinders conjugation
in this molecular system (cf. 300, 321, and 342 nm for
F igu r e 3. Room temperature optical absorption spectrum and
the PL spectrum (11 K) of [Hg-T(DPF)T] in solid.
∞
[
Au-T(DPF)T]1, [Pt-T(DPF)T]1, and [Pt-T(DPF)T]∞,
respectively). In other words, the energy of the S1 singlet
state (and hence the Eg value) can be varied depending
on the electronic properties of the central spacer group,
which is found to be vital for governing the efficiency of
triplet-state emission (vide infra).
The thin film photoluminescence (PL) spectra of the
new compounds were measured at various tempera-
tures. In dilute fluid solutions at 290 K, we observe an
1
intense purple-blue (ππ*) emission peak near 400 nm
for each of them which is due to fluorescence (S1 f S0).
As the temperature is cooled to 11 K, we observe
virtually no fluorescence band but only the phospho-
rescence band associated with the organic chromophore.
At 11 K, the principal emissive peak occurs at ca. 458
and 498 nm for [Pt-T(DPF)T]∞ and [Hg-T(DPF)T]∞,
respectively, and at ca. 451, 499, and 494 nm for [Pt-
T(DPF)T]1, [Au-T(DPF)T]1, and [Hg-T(DPF)T]1, re-
spectively. The large Stokes shifts of these lower-lying
emission peaks from the dipole-allowed absorptions
F igu r e 4. Temperature dependence of the PL of [Pt-
T(DPF)T]
1
.
band increases in intensity, which is accompanied by a
well-resolved vibronic structure, and such an increase
in intensity indicates a long-lived triplet excited state
that is more sensitive to thermally activated nonradia-
tive decay mechanisms. The lifetime (τ) values at the
peak maxima were found to be in the microsecond
regime (11.9 ( 1.9 to 48.1 ( 2.4 µs) at 77 K, in line with
those for the phosphorescence observed in similar
(
1.46-1.56 eV, see Figures 2 and 3) plus the long
emission lifetimes are indicative of their triplet parent-
3
age, and they are thus assigned to the (ππ*) excited
states of the bis(ethynylphenyl)fluorene core.2
5,34,37
The
assignment can also be interpreted in terms of the
observed temperature dependence of the PL data, in
accordance with earlier work on platinum(II) polyynes.
Representative examples of the temperature depend-
encies of the PL spectra for the monomers and the
polymers are displayed in Figures 4-7. In each case,
when the temperature is lowered, the triplet emission
2
5-33
polymetallaynes previously reported.
In contrast,
the solid-state emission appears broad and unstructured
at room temperature for our mercurial compounds,
which is characteristic of an aggregate or excimer site
5
6
that is only weakly emissive.

4
502 Wong et al.
Macromolecules, Vol. 37, No. 12, 2004
F igu r e 5. Temperature dependence of the PL of [Pt-
T(DPF)T]
∞
.
F igu r e 8. Electronic energy level diagram of diphenylfluor-
ene-based metal alkynyls determined from absorption and PL
data. Dashed lines represent the levels for [Pt-T(BP)T]
Pt-T(BP)T] . The S levels are arbitrarily shown to be of
equal energy.
1
and
[
∞
0
als.28 This finite exchange energy implies an excited
state which is self-localized. According to the energy gap
law, efficient phosphorescence is more readily accessible
for higher S0-T1 energy gaps, and we have shown that
the organic triplet emissions of diphenylfluorene-based
aryleneethynylenes of large optical gaps have been
“
illuminated” by the heavy-atom effect of group 10-12
transition metal elements.
On the basis of the absorption and PL data, we can
construct an energy scheme for the lower-lying excita-
tions shown in Figure 8 for the new polymers and the
monomers. The energy values are absolute values with
F igu r e 6. Temperature dependence of the PL of [Hg-
T(DPF)T]
∞
.
8
10
respect to the S0 ground state. For the d Pt(II) and d
Hg(II) systems, the lowest T1 state remains strongly
localized, as can be inferred from the small energy
difference between triplet emissions in the monomers
and in the polymers. Previous calculations performed
for trans-[-Pt(PBu3)2CtC(p-C6H4)CtC-]n (abbreviated
as [Pt-T(P)T]∞) have also shown the triplet to be
5
5
confined onto the phenylene ring. Substitution of the
metal groups does not seem to alter this strong confine-
ment. For all these efficient phosphorescent metal-
organic systems containing the conjugation-interrupting
diphenylfluorene segment, they show T1-S0 gaps of 2.5
eV or above, which correspond to S1(PL)-S0 gaps of over
3
.1 eV (3.18-3.38 eV). Apparently, the T1 levels for the
Pt(II) compounds are higher than those for the corre-
sponding Au(I) and Hg(II) congeners in the present
system. The hindered conjugation by the use of diphe-
nylfluorene unit in [Pt-T(DPF)T]1 and [Pt-T(DPF)T]∞
shifts the phosphorescence to the blue by 0.46 and 0.45
eV, respectively, compared to the bi(p-phenylene)-
containing Pt(II) counterparts [Pt-T(BP)T]1 and [Pt-
T(BP)T]∞ (Chart 1). These data reveal that the intensity
of phosphorescence reduces with the energy of the T1-
F igu r e 7. Temperature dependence of the PL of [Au-
T(DPF)T]
1
.
To examine the spatial extent of the singlet and trip-
let excitons in our systems, values of ∆E(S0-T1) (energy
gap between S0 and T1) were compiled to be 2.48-2.75
eV for all the metal diynes and polyynes. The measured
∆
E(S1-T1) values are 0.63, 0.65, 0.70, 0.69, and 0.70
eV for [Pt-T(DPF)T]1, [Pt-T(DPF)T]∞, [Hg-T(DPF)T]1,
Hg-T(DPF)T]∞, and [Au-T(DPF)T]1, respectively, and
they correspond well with the S1-T1 energy gap of 0.7
0.l eV for similar π-conjugated Pt(II), Au(I), and Hg-
S emission and the rate of intersystem crossing (ISC)
0
is higher for metal polyyne system with a larger optical
[
gap. This was also supported by the peak height ratio
from triplet emission to singlet emission at 77 K,
∆E(T fS , S fS ) (Table 4), which can serve as a good
(
1
0
1
0
2
5,34,37
(II) polyynes
and are close to the gaps estimated
indicator to evaluate the relative ISC efficiency. Clearly,
1
7,57,58
for a series of related organic conjugated polymers.
the order of S -T crossover efficiency is [Pt-T(DPF)T]
1
1
∞
We attribute such a constant ∆E(S1-T1) value to the
exchange energy and possibly some additional constant
contribution due to the admixture of the metal orbit-
(68) > [Pt-T(BP)T] ≈ [Pt-T(P)T] (19) and [Pt-
∞
∞
T(DPF)T]1 (30) > [Pt-T(BP)T]1 ≈ [Pt-T(P)T]1 (6).
Based on the work by others that the ISC efficiency

Macromolecules, Vol. 37, No. 12, 2004
Metal Diynes and Polyynes 4503
Ch a r t 1a
a
BP represents the bi(p-phenylene) moiety.
Ta ble 4. Tr ip let En er gies a n d In ter system Cr ossin g
Efficien cies of P la tin u m (II) Mon om er s a n d P olym er s
Con ta in in g Dip h en ylflu or en e, Bi(p-p h en ylen e), a n d
p-P h en ylen e Gr ou p s
intrinsically lead to the more efficient phosphorescence
in metal-containing aryleneethynylenes. The successful
use of the conjugation-interrupting sp -carbon atom in
the cardo diphenylfluorene structure in such metal
polyynes can limit the effective conjugation length and
gives rise to efficient crossover between S1 and T1 states.
3
E(T1-S0)/eV
∆E(T1fS0, S1fS0)a
[
[
[
[
[
[
Pt-T(DPF)T]1
Pt-T(DPF)T]∞
Pt-T(BP)T]1
Pt-T(BP)T]∞
2.75
2.71
2.29
2.26
2.39
2.38
29.6
68.0
6.0
18.9
5.9
18.5
Con clu d in g Rem a r k s
b
Pt-T(P)T]1
The work reported here describes the synthesis of a
new series of metal diynes and polyynes of group 10-
12 transition metals incorporating the diphenylfluorene
moiety. All the compounds were analytically and spec-
troscopically characterized to possess a well-defined size
and structure. The materials are organic-soluble, solu-
b
Pt-T(P)T]∞
a
Ratio of the intensities of triplet emission to singlet emission
b
at 77 K. [Pt-T(P)T]1 and [Pt-T(P)T]∞ refer to the Pt diyne and
polyyne containing p-phenylene spacer, and the data were taken
from ref 29.
3
tion-processable, and thermally stable. While the sp -
(
ΦISC) is close to unity for third-row transition metal
carbon atom in the cardo group hinders conjugation,
these diphenylfluorene-based materials display strong
organic triplet emissions. All the three transition metals
5
9-61
chromophores,
the radiative (kr) and nonradiative
(
knr) decay rates are related to the measured lifetime of
triplet emission (τT) and the phosphorescence quantum
yield (ΦP) by the following expressions:
(viz. Pt, Au, and Hg) can exert heavy-atom effects in
the enhancement of ISC rate, and the effect is most
significant for Pt having the highest T1 energy state.
Reduced conjugation in the presence of the non-π-
conjugated segment shifts the optical gap and the
phosphorescence band to the blue as compared to other
platinum polyynes with carbocyclic and heterocyclic
knr ) (1 - Φ )/τ
P
T
k ) Φ /τ
T
r
P
3
The measured ΦP and τT values for [Pt-T(DPF)T]∞
are 0.25 ( 0.05 and 10.0 ( 0.5 µs at 20 K, respectively.
For [Pt-T(DPF)T]∞, the values calculated for knr and
spacers. We consider that the sp -carbon site in diphe-
nylfluorene is an effective conjugation-interrupter to
limit the conjugation length in metal polyynes, leading
to materials of high optical gaps and high-energy triplet
states. Our results further demonstrate that higher S0-
T1 energy gaps can facilitate efficient phosphorescence.
It is anticipated that a structure-function (i.e., photo-
luminescence) relationship can be established, and
valuable insight into the photophysical nature of (-Ct
C-Ar-CtC-)n conjugated materials can be eventually
derived. Future work should focus on polymers with
high-energy triplets (and concurrently high optical
gaps), and such an investigation is desirable for opto-
electronic applications that utilize the T1 state for light
emission through light-harvesting techniques.
4
-1
4
-1
kr are (9.5 ( 0.5) × 10 s and (2.5 ( 0.5) × 10 s at
0 K, respectively. For phosphorescence in aromatic
hydrocarbon molecules, kr is typically found to be
2
-
1 62
between 0.1 and 1 s
.
So, the heavy-atom effect of Pt
increases the radiative decay rate for the triplet emis-
sion by 4 orders of magnitude, and incorporation of the
,9-diphenylfluorene group in the present system dis-
9
playing larger T1-S0 gaps can speed up the radiative
decay rate as compared to the p-phenylene-spaced Pt
3
-1
25
polymer (kr ) (6 ( 4) × 10 s at 20 K). The findings
corroborate with the previous work that high-energy
triplet states (and concurrently high optical gaps)

4
504 Wong et al.
Macromolecules, Vol. 37, No. 12, 2004
Ack n ow led gm en t. We are grateful to the Hong
Kong Research Grants Council (Grants HKBU 2048/
1P and 2022/03P) and the Hong Kong Baptist Univer-
sity (FRG/01-02/II-48) for financial support. We also
thank Miss Carmen Ng for helpful discussions.
(28) Wilson, J . S.; K o¨ hler, A.; Friend, R. H.; Al-Suti, M. K.; Al-
Mandhary, M. R. A.; Khan, M. S.; Raithby, P. R. J . Chem.
Phys. 2000, 113, 7627-7634.
29) Chawdhury, N.; K o¨ hler, A.; Friend, R. H.; Younus, M.; Long,
N. J .; Raithby, P. R.; Lewis, J . Macromolecules 1998, 31, 722-
727.
0
(
(30) Wong, W.-Y.; Wong, C.-K.; Lu, G.-L.; Lee, A. W.-M.; Cheah,
K.-W.; Shi, J .-X. Macromolecules 2003, 36, 983-990.
Su p p or tin g In for m a tion Ava ila ble: Preparations of
ligand precursors, tables of X-ray crystal data for [Pt-
(31) Wong, W.-Y.; Lu, G.-L.; Choi, K.-H.; Shi, J .-X. Macromolecules
002, 35, 3506-3513.
2
T(DPF)T]
and [Pt-T(BP)T]
charge via the Internet at http://pubs.acs.org.
1
, and phosphoresecence spectra of [Pt-T(DPF)T]
∞
(
32) Wong, W.-Y.; Choi, K.-H.; Lu, G.-H. Macromol. Rapid Com-
mun. 2001, 22, 461-465.
∞
at 77 K. This material is available free of
(
33) Chawdhury, N.; K o¨ hler, A.; Friend, R. H.; Wong, W.-Y.; Lewis,
J .; Younus, M.; Raithby, P. R. Corcoran, T. C.; Al-Mandhary,
M. R. A.; Khan, M. S. J . Chem. Phys. 1999, 110, 4963-4970.
34) Chao, H.-Y.; Lu, W.; Li, Y.; Chan, M. C. W.; Che, C.-M.;
Cheung, K.-K.; Zhu, N. J . Am. Chem. Soc. 2002, 124, 14696-
Refer en ces a n d Notes
(
(
1) Conjugated Polymeric Materials: Opportunities in Electron-
ics, Optoelectronics and Molecular Electronics; Br e´ das, J . L.,
Chance, R. R., Eds.; Kluwer Academic Publishers: Dordrecht,
1
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