Self-assembly molecular architectures with novel cyclic dimers

Article abstract of DOI:10.1016/j.jorganchem.2005.10.046

Highly emissive conjugated compounds containing pyridine (or pyrimidine) and cyano ligands have been synthesized by palladium-catalyzed cross-coupling reaction. These ligands readily react with Re(CO)₃(THF)₂Br to form cyclic supramol

Full text of DOI:10.1016/j.jorganchem.2005.10.046

Journal of Organometallic Chemistry 691 (2006) 975–982
www.elsevier.com/locate/jorganchem
Self-assembly molecular architectures with novel cyclic dimers
a,
b,
*
Ping-Hsin Huang a,b,c, Jiann T. Lin *, Ming-Chang P. Yeh
a
Institute of Chemistry, Academia Sinica, No. 128, Sec. 2, Yang-Chiu-Yan Road, Taipei 115, Taiwan, Republic of China
b
Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan, Republic of China
Kang-Ning Junior College of Medical Care and Management, Taipei, Taiwan, Republic of China
c
Received 12 May 2005; received in revised form 25 October 2005; accepted 28 October 2005
Available online 5 December 2005
Abstract
Highly emissive conjugated compounds containing pyridine (or pyrimidine) and cyano ligands have been synthesized by palladium-
catalyzed cross-coupling reaction. These ligands readily react with Re(CO)3(THF)2Br to form cyclic supramolecules by self-assembly
processes. At room temperature these supramolecules are emissive, and the emission is ligand-localized, as evidenced from the Stokes
shift and the lifetime data.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Supramolecule; Self-assembly; Rhenium
1. Introduction
als tunable through the redox of the metal center [5]; (c)
sensing materials to detect molecules or ions [6].
We have been interested in metal-containing macrocy-
cles in which metals are linked by conjugated spacers only.
Transition metal complexes generally suffer from very low
luminescent quantum yields due to the presence of heavy
atom effects [7]. It was thought that use of strongly emissive
spacers would partially compensate for this effect. The
prerequisite for the construction of self-assembly metal-
containing macrocycles is the availability of ditopic (or oli-
gotopic) ligands [8], and oligo- and polypyridyl (cyano)
ligands are probably the most widely used ligands for this
purpose.
Metal-containing supramolecules and coordination
polymers is an area of expanding development because
these compounds not only provide useful models for
molecular recognition and light harvesting but also have
potential applications in materials science [1]. Self-assem-
bly inorganic cyclophane molecules have emerged as an
important class of supramolecules in the past decade [2].
Such macrocycles are attractive in sensing technology: (a)
the cavity inside these molecules can trap some guest mol-
ecules and (b) the detection of the guest molecules is possi-
ble through the photoluminescence characteristics or
changes in redoxpotential values of the host.
Macrocycles in which metals are all linked by conju-
gated spacers appear to be very interesting because molec-
ular wire type spacers are expected to enhance the
sensitivity of chemosensors, similar to conjugated poly-
mer-based chemical sensors [3]. Such compound may also
find applications in other aspects, such as: (a) third-order
non-linear optical materials [4]; (b) electrochromic materi-
Here, we describe the preparation and characterization
of a series of fac-tricarbonyl rhenium(I)-base self-assembly
macrocyclic complexes with conjugated ligands containing
pyridyl (pyrimidyl) and cyano moiety.
2. Results and discussion
The conjugated ligands L1–L4 were conveniently pre-
pared by a multi-step reaction. Palladium-catalyzed Sono-
gashira coupling [9] reaction with trimethylsilylacetylene
and desilylation by KOH in methanol at room temperature
led to the desired terminal acetylenes. These terminal
*
Corresponding authors. Tel.: +886 2 27898522; fax: +886 2 27831237.
E-mail address: jtlin@chem.sinica.edu.tw (J.T. Lin).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.10.046

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P.-H. Huang et al. / Journal of Organometallic Chemistry 691 (2006) 975–982
acetylenes underwent facile cross-coupling reactions with
4-bromo-2-iodopyridine, 4-bromo-2-iodopyrimidine and
4-bromo-2-chloropyridine to provide the conjugated
ligands L1–L4 in good yields. All the ligands described here
were thoroughly characterized by NMR, mass spectrome-
try, and elemental analysis. To facilitate ligand substitution
reaction of L1–L4 for CO in Re(CO)5Br, Re(CO)5Br was
converted to Re(CO)3(THF)2Br by refluxing the THF solu-
tion of Re(CO)5Br for one day under an N2 atmosphere
[10]. The conjugated ligands L1–L3 readily reacted with
Re(CO)3(THF)2Br in THF solvent to yield soluble molec-
ular cyclic dimers S1, S2 and S3 with a rectangular geom-
etry (Schemes 1 and 2). On the contrary, the reaction of L4
with Re(CO)3(THF)2Br in THF solvent only leads to
monomeric complex S4 which contains two L4 ligands
(Scheme 3).
tion of the (M ꢀ CO)+ fragment fits well with the simulated
spectra (Fig. 2(b)). Furthermore, the peaks due to higher
oligomers are elusive. The FABMS of S1 and S2 are simi-
lar to those of S3. For S4, there was no fragment due to
cyclic dimers analogous to S1–S3. Instead, only the parent
peak attributed to the monomer was detected.
Infrared spectra in the carbonyl stretching region for
S1–S4 exhibit tricarbonyl stretching patterns between
1890 and 2024 cmꢀ1 that are typical of fac-Re(LL)(CO)3X
complex [12]. One broad m(CN) peak with a prominent
shoulder was observed in CH2Cl2. Coordination of the
ligands renders the m(CN) values to be lower than those
of the corresponding free ligands by ꢁ20 cmꢀ1. As
expected, a-pyridyl protons in these cyclic complexes S1,
S2 and S3 shift downfield relative to their free ligands
due to the dative bonding nature of the nitrogen (pyridyl
or pyrimidyl) lone pair to the Re(I) center. On the contrary,
the chemical shifts of the a-pyridyl protons of S4 remain
almost the same as those of L4. This observation further
supports the monomeric nature of S4.
The growth of single crystals for S1–S4 was not success-
1
ful. However, the elemental analyses, mass spectra, the H
NMR, the infrared and the UV–Vis spectra of S1–S4
(Tables 1 and 2) are consistent with their formulation.
The isomer of Sn (n = 1–3), Sn0, with a triangular geometry
as shown in Fig. 1, cannot be excluded [11]. Fig. 2 is the
FABMS of S3. Though no parent peak was observed,
the peaks attributed to (M ꢀ CO)+ and (M ꢀ Br)+ can be
clearly identified (Fig. 2(a)). The relative isotope distribu-
Table 2 summarizes the photophysical data of L1–L4
and S1–S4. All the ligands possess intense p–p* absorption
in the near-UV region. The metal complexes S1–S3 possess
two or three substantially overlapping ligand-localized p–
p* and MLCT (metal to pyridyl or to pyrimidyl dp ! pp*)
N
N
Br
N
L
1
NH
L 2
N
1
N
N
N
N
CN
N
Re(CO)3(THF)2Br
r
B
)
2
F
H
N
T
(
)
3
O
Br
C
(
e
R
N
N
N
N
I
Re(CO)3Br
Re(CO)3Br
N
N
N
HI
N
Br(OC)3Re
N
Br(OC)3Re
N
S
Br
1
S 2
N
N
Br
N
Scheme 1.

P.-H. Huang et al. / Journal of Organometallic Chemistry 691 (2006) 975–982
977
N
N
H
N
N
N
N
Br
I
Br
N
2
N
N
Br(OC)3Re
N
N
N
N
Re(CO)3(THF)2Br
N
N
N
N
Re(CO)3Br
N
N
S 3
L 3
Scheme 2.
N
N
N
Cl
N
H
CN
HI
N
Br
N
I
Cl
3
4
N
N
N
Re(CO) (THF) Br
3
2
N
N
N
N
Re(CO) Br
3
L 4
N
S 4
N
Scheme 3.
ranging from 1.37 to 2.28 ns. The relatively small Stokes
shift and the short lifetime indicate that the emission is
mainly ligand-localized p–p* fluorescence. The solution
quantum yields of S1–S4 are at least one order lower than
those of their free ligands. This can be attributed to the
large spin–orbit coupling exerted from Re(I) atoms [13],
Table 1
Infrared CO and CN stretching frequency data for the compounds in
CH2Cl2
Compound
m (CN, cmꢀ1
)
m (CO, cmꢀ1
)
L1
S1
2230 (w)
2208 (w)
2023 (s)
1909 (m)
1923 (m)
1924 (m)
1909 (m)
1891 (s)
1906 (s)
1890 (s)
1892 (s)
1
which led to intersystem crossing from the p–p* state to
L2
S2
2229 (w)
2210 (w)
2026 (s)
2024 (s)
2024 (s)
3
3
the non-emissive MLCT and/or p–p* state [14].
Whether ligation of L1–L3 to two rhenium centers to
form S1–S3 proceeds simultaneously or in a stepwise man-
ner is not known at present. No monomeric analogues of
S4 can be detected if only 0.5 equivalent of L1–L3 was used
in the reaction. Though L1 and L4 are isomeric, only the
former leads to the formation of the cyclic dimmer. The
geometrical constraint around the Re center with pyridine
(or pyridimidine) linkage is expected to be very similar in
S1–S3. However, the two pyridyl nitrogen atoms are far-
ther away compared to those in S1–S3, and are not likely
to span the cis coordination sites of the Re(CO)3Br
fragment.
L3
S3
2228 (w)
2209 (w)
L4
S4
2230 (w)
2213 (w)
absorption bands, with the latter appearing at lower energy
(see Fig. 3 for L1 and S1). The monomeric complex, S4,
has no MLCT bands due to the absence of Re–pyridine
or pyrimidine linkage. At room temperature the complexes
S1–S4 exhibit wavelength-independent luminescence and a
single-exponential decay profile with emission lifetime

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P.-H. Huang et al. / Journal of Organometallic Chemistry 691 (2006) 975–982
Table 2
Electronic absorption and emission data for the compounds
Compound
Absorption spectra kmax (nm)
Emissiona,b kem (nm)
Quantum yield Uem (%)
Lifetime s (ns)
krc (s)
L1
S1
L2
S2
L3
S3
L4
S4
a
305, 327, 394
303, 330, 480
270, 377
300 (sh), 403
272, 376
279 (sh), 429
365
367
545
564
496
513
513
517
479
497
61
0.1
52
0.3
50
0.1
76
3
1.32
1.61
1.65
2.28
2.13
1.97
1.31
1.35
4.62 · 108
6.21 · 105
3.15 · 108
1.32 · 106
2.35 · 108
5.08 · 105
5.76 · 108
2.22 · 107
k
ex = 350 nm.
b
c
CH2Cl2 solution at room temperature.
kr = U/s.
(CO)3Br
Re
and Re(CO)5Br [19] were prepared by published proce-
dures with modifications. Infrared spectra were measured
on a Perkin–Elmer Paragon 1000 FT-IR spectrometer.
The 1H NMR spectra were measured by using Bruker
AMX400 spectrometers. Electronic absorption spectra
were obtained on a Cary 50 prube UV–Vis spectrometer.
Emission spectra were recorded in deoxygenated solu-
tion at 298 K with a Hitachi F-4500 fluorescence spectrom-
eter. The emission spectra were collected on samples with
o.d. ꢁ0.1 at the excitation wavelength. In all emission
experiments, the sample solutions were filtered through
0.22 lm Millipore filters prior to measurement. UV–Vis
spectra were checked before and after irradiation to moni-
tor possible sample degradation. Emission maxima were
reproducible to within 2 nm. Luminescence quantum yields
(Uem) were calculated relative to [RuII(bpy)3]Cl2 in air-
equilibrated aqueous solution (Uem = 0.028) [20]. Lumines-
cence quantum yields were taken as the average of three
separate determinations and were reproducible to within
10%.
N
N
(CO)3Br
Re
N
N
N
N
S 2'
Fig. 1. The structural isomer of S2, S20, with triangular geometry.
In conclusion, we have synthesized highly emissive con-
jugated ligands containing a pyridine or pyrimidine moiety
as the central core, and cyano moiety as the end. These
compounds are demonstrated to be useful building blocks
for the construction of macrocyclic supramolecules with
unprecendented geometries. Because of the luminescent
nature of some of the complexes, sensing applications
may be possible. Extension and further exploration of this
study is in progress.
Room-temperature luminescence lifetimes were re-
corded on a SLM 48000S phase-modulation lifetime fluo-
rescence spectrophotometer. The excitation light passed
through a monochromator and was then intensity modu-
lated at a different frequency by a Debye–Sears ultrasonic
modulator. The sample and reference solutions were placed
in a two-chamber turret. The emission intensities of each at
the observation wavelength were approximately balanced
by neutral density filters. The phase shift and modulation
of each sample was measured alternately 25 times. The
results were averaged and analyzed by an interfaced IBM
computer. The errors forfitted lifetimes are estimated to
be within 10%.
3. Experimental
3.1. General procedures
All reactions and manipulations were carried out under
N2 with the use of standard inert atmosphere and Schlenk
techniques. Solvents were dried by standard procedures.
All column chromatography was performed under N2 with
the use of silica gel (230–400 mesh, Macherey–Nagel
GmbH & Co.) as the stationary phase in a column of
30 cm in length and 2.0 cm in diameter. 4-Ethynylbenzonit-
rile [15], 5-bromo-2-iodopyridine [16], (4-ethynylphe-
nyl)diphenylamine [17], 5-bromo-2-iodopyrimidine [18]
3.2. Synthesis of 4-(5-bromopyridine-2-ylethynyl)-
benzonitrile (1)
5-Bromo-2-iodopyridine (0.284 g, 1.0 mmol), 4-ethynyl-
benzonitrile (0.140 g, 1.1 mmol), Pd(PPh3)2Cl2 (21.1 mg,
3 mmol%), CuI (11.7 mg, 6 mmol%), triphenylphosphine
(6.6 mg, 2.5 mmol), diethylamine (10 mL) and THF
(20 mL) were charged sequentially in a two-necked flask

P.-H. Huang et al. / Journal of Organometallic Chemistry 691 (2006) 975–982
979
Fig. 2. (a) Full range FABMS spectra of complex S3. (b) Observed (left) and calculated (right) FABMS for complex S3 fragment, (M ꢀ CO)+.
under nitrogen atmosphere and heated to reflux for 24 h.
After cooling, the volatiles were removed under vacuum,
and the resulting solid was extracted into diethyl ether.
The organic extract was washed with brine solution, dried
over anhydrous MgSO4 and filtered. Evaporation of the
solvent left a brown residue that was chromatographed
through silica gel using dichloromethane/hexane mixture
as eluant. Compound 1 was obtained as a white solid in
3.3. Synthesis of 4-(5-(4-diphenylaminophenyethynyl)
pyridine-benzonitrile) (L1)
4-Ethynylphenyldiphenylamine (0.808 g, 6.0 mmol),
4-(5-bromopyridine-2-ylethynyl)benzonitrile (1.70 g,
3.0 mmol), Pd(dba)2 (20 mg, 1 mmol%), t-BuONa (0.45 g,
4.5 mmol) and toluene (50 mL) were charged in a two-
necked flask under nitrogen atmosphere, then (t-Bu)3P
(0.17 mL, 0.12 mmol, 0.706 M) was added after 10 min,
and the solution was heated to reflux for 24 h. After cool-
ing, the volatiles were removed under vacuum, and the
resulting solid was extracted into diethyl ether. The organic
extract was washed with brine solution, dried over anhy-
drous MgSO4 and filtered. Evaporation of the solvent left
1
73% yield. MS (EI): m/e 283 (M+); H NMR (CDCl3):
7.41 (d, J = 8.3 Hz, 1 H, NCCH), 7.62 (d, J = 8.2 Hz, 2
H, C6H4), 7.65 (d, J = 8.2 Hz, 2 H, C6H4), 7.83 (dd,
J = 2.4, 8.4 Hz, 1 H, BrCCH), 8.67 (d, J = 2.2 Hz, 2 H,
NCH); Anal. Calc. for C14H7BrN2: C, 59.39; H, 2.49; N,
9.89. Found: C, 59.66; H, 2.35; N, 10.01%.

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P.-H. Huang et al. / Journal of Organometallic Chemistry 691 (2006) 975–982
mmol), Pd(dba)2 (20 mg, 1 mmol%), t-BuONa (0.45 g,
1.2
1.0
0.8
0.6
0.4
0.2
0.0
600
500
400
300
200
100
0
L1
S1
4.5 mmol) and toluene (50 mL) were charged in a two-
necked flask under nitrogen atmosphere then (t-Bu)3P
(0.17 mL, 0.12 mmol, 0.706 M) was added after 10 min
and heated to reflux for 24 h. After cooling, the volatiles
were removed under vacuum, and the resulting solid was
extracted into diethyl ether. The organic extract was washed
with brine solution, dried over anhydrous MgSO4 and fil-
tered. Evaporation of the solvent left a brown residue that
was chromatographed through aluminum oxide using ethyl
acetate/hexane mixture (1:9) as eluant. Compound L2 was
obtained as a yellow solid in 60% yield. MS (FAB): m/e
1
422.1 (M + H)+; H NMR (CD2Cl2): 7.05–7.92 (m, 12 H,
300
400
500
600
700
aromatic), 7.41 (dd, J = 2.0, 8.7 Hz, 1 H, NCCHCH), 7.59
(d, J = 8.2 Hz, 2 H, C6H4). 7.63 (d, J = 8.2 Hz, 2 H,
C6H4), 7.84 (d, J = 8.3 Hz, 1 H, NCCH), 8.24 (d,
J = 2.0 Hz, 1 H, NCH); Anal. Calc. for C30H19N3: C,
85.49; H, 4.54; N, 9.97. Found: C, 85.38; H, 4.32; N,
9.72%; IR (m(CN), cmꢀ1): 2229 w.
Wavelength (nm)
Fig. 3. Electronic absorption spectra and emission spectra of L1 (solid
line) and S1 (dotted line) in CH2Cl2.
a brown residue that was chromatographed through alumi-
num oxide using ethyl acetate/hexane mixture (1:9) as elu-
ant. Compound L1 was obtained as a yellow solid in 65%
yield. MS (FAB): m/e 472.1 (M + H)+; 1H NMR (CD2Cl2):
7.00 (d, J = 8.7 Hz, 2 H, NC6H4), 7.05–7.31 (m, 10 H, aro-
matic), 7.36 (d, J = 8.7 Hz, 2 H, NC6H4), 7.49 (d,
J = 8.1 Hz, 1 H, NCCH). 7.63 (d, J = 8.6 Hz, 2 H,
C6H4), 7.66 (d, J = 8.6 Hz, 2 H, C6H4), 7.77 (dd, J = 1.9,
8.0 Hz, 1 H, NCCHCH), 8.72 (d, J = 1.4 Hz, 1 H,
NCH); Anal. Calc. for C34H21N3: C, 86.60; H, 4.49; N,
8.91. Found: C, 86.32; H, 4.21; N, 8.88%; IR (m(CN),
cmꢀ1): 2230 w.
3.6. Synthesis of 4-(5-bromopyrimidin-2-ylethynyl)
benzonitrile (2)
5-Bromo-2-iodopyrimidine (0.29 g, 1.0 mmol), 4-ethynyl
benzonitrile(0.140 g, 1.1 mmol), Pd(PPh3)2Cl2 (21.1 mg,
3 mmol%), CuI (11.7 mg, 6 mmol%), triphenylphosphine
(6.6 mg, 2.5 mmol), diethylamine (10 mL) and THF
(20 mL) were charged sequentially in a two-necked flask
under nitrogen atmosphere and heated to reflux for 24 h.
After cooling, the volatiles were removed under vacuum,
and the resulting solid was extracted into diethyl ether.
The organic extract was washed with brine solution, dried
over anhydrous MgSO4 and filtered. Evaporation of the
solvent left a brown residue that was chromatographed
through silica gel using dichloromethane/hexane mixture
as eluant. Compound 2 was obtained as a white solid in
3.4. Synthesis of supramolecule (S1)
The complex Re(CO)5Br (406 mg, 1.0 mmol) was
dissolved in THF solvent (50 mL) and heated to reflux for
24 h under nitrogen atmosphere. Complex Re(CO)3-
(THF)2Br was formed during this time, then 4-(5-(4-
diphenylaminophenyethynyl)pyridine-benzo-nitrile) (L1)
(471 mg, 1.0 mmol) dissolved in THF was added via a can-
nula and heated to 60 ꢁC for 24 h. After cooling, the vola-
tiles were removed, and the residue was collected by
filtration and washed thoroughly with ether, toluene, and
hexane. Recrystallization of the crude product from dichlo-
romethane/hexane gave complex S1 as a purple solid in 92%
yield. MS (FAB): m/e 1614.1 ((M ꢀ CO)+, 187Re; 81Br); 1H
NMR (CD2Cl2): 6.95–7.47 (m, 28 H, aromatic), 7.76 (d,
J = 8.5 Hz, 2 H, NCCH), 7.81 (d, J = 8.5 Hz, 8 H, C6H4),
8.45 (d, J = 8.4 Hz, 2 H, NCCHCH), 9.25 (d, J = 1.7 Hz,
2 H, NCH); Anal. Calc. for C74H42Br2 N6O6Re2: C, 54.08;
H, 2.58; N, 5.11. Found: C, 54.41; H, 2.72; N, 4.98%; IR
(m(CO), cmꢀ1): 2023 s, 1909 m, 1891 s; (m(CN), cmꢀ1):
2208 w.
1
70% yield. MS (EI): m/e 283 (M+); H NMR (CDCl3): 766
(d, J = 8.5 Hz, 2 H, C6H4), 7.73 (d, J = 8.5 Hz, 2 H, C6H4),
8.82 (s, 2 H, BrCCH); Anal. Calc. for C13H6BrN3: C, 54.96;
H, 2.13; N, 14.79. Found: C, 54.86; H, 2.15; N, 14. 43%.
3.7. Synthesis of 4-(5-diphenylaminopyrimidin-2-ylethynyl)-
benzonitrile (L3)
Diphenylamine (1.02 g, 6.0 mmol), 4-(5-bromopyr-
imidin-2-ylethynyl)benzonitrile (2) (0.85 g, 3.0 mmol),
Pd(dba)2 (20 mg, 1.0 mmol%), t-BuONa (0.45 g, 4.5 mmol)
and toluene (50 mL) were charged in a two-necked flask
under nitrogen atmosphere, then (t-Bu)3P (0.17 ml,
0.12 mmol, 0.706 M) was added after 10 min, and the solu-
tion was heated to reflux for 24 h. After cooling, the volatiles
were removed under vacuum, and the resulting solid was
extracted into diethyl ether. The organic extract was washed
with brine solution, dried over anhydrous MgSO4 and fil-
tered. Evaporation of the solvent left a brown residue that
was chromatographed through aluminum oxide using ethyl
acetate/hexane mixture (1:9) as eluant. Compound L3 was
3.5. Synthesis of (4-(5-naphthalen-1-yl-phenylamino)-
pyridin-2-ylethynyl)benzonitrile (L2)
Naphthalen-yl-phenylamine (0.658 g, 6.0 mmol), 4-(5-
bromopyridine-2-ylethynyl)benzonitrile (1) (1.70 g, 3.0

P.-H. Huang et al. / Journal of Organometallic Chemistry 691 (2006) 975–982
981
obtained as a yellow solid in 50% yield. MS (FAB): m/e
Pd(dba)2 (20.0 mg, 1 mmol%), t-BuONa (0.45 g, 4.5 mmol)
and toluene (50 mL) were charged in a two-necked flask
under nitrogen atmosphere then (t-Bu)3P (0.17 ml,
0.12 mmol, 0.706 M) was added after 10 min and heated
to reflux for 24 h. After cooling, the volatiles were removed
under vacuum, and the resulting solid was extracted into
diethyl ether. The organic extract was washed with brine
solution, dried over anhydrous MgSO4 and filtered. Evap-
oration of the solvent left a brown residue that was chro-
matographed through aluminum oxide using ethyl
acetate/hexane mixture (1:9) as eluant. Compound L4
was obtained as a yellow solid in 62% yield. MS (FAB):
1
373.1 (M + H)+; H NMR (CD2Cl2): 7.09–7.39 (m, 10 H,
aromatic), 7.63 (d, J = 8.3 Hz, 2 H, C6H4), 7.70 (d,
J = 8.3 Hz, 2 H, C6H4). 8.39 (s, 2 H, NCH); Anal. Calc.
for C25H16N4: C, 80.63; H, 4.33; N, 15.04. Found: C,
80.35; H, 4.37; N, 14.92%; IR (m (CN), cmꢀ1): 2228 w.
3.8. Synthesis of 4-(6-chloropyridine-3-ylethynyl)-
benzonitrile (3)
5-Bromo-2-chloropyridine (0.193 g, 1.0 mmol), 4-eth-
ynylbenzonitrile (0.140 g, 1.1 mmol), Pd(PPh3)2Cl2 (21.1 mg,
3 mmol%), CuI (11.7 mg, 6 mmol%), triphenylphosphine
(6.6 mg, 2.5 mmol), diethylamine (10 mL) and THF
(20 mL) were charged sequentially in a two-necked flask
under nitrogen atmosphere and heated to reflux for
24 h. After cooling, the volatiles were removed under vac-
uum, and the resulting solid was extracted into diethyl
ether. The organic extract was washed with brine solu-
tion, dried over anhydrous MgSO4 and filtered. Evapora-
tion of the solvent left a brown residue that was
chromatographed through silica gel using dichlorometh-
ane/hexane mixture as eluant. Compound 3 was obtained
as a white solid in 75% yield. MS (EI): m/e 239.8
1
m/e 422.0 (M + H)+; H NMR (CD2Cl2): 7.05–8.00 (m,
12 H, aromatic), 7.48 (d, J = 8.1 Hz, 1 H, NCCH), 7.59
(d, J = 8.4 Hz, 2 H, C6H4). 7.66 (d, J = 8.4 Hz, 2 H,
C6H4) 7.74 (dd, J = 2.3;8.0 Hz, 1 H, NCHCCH), 8.31 (d,
J = 2.3 Hz, 1 H, NCH); Anal. Calc. for C30H19N3: C,
85.49; H, 4.54; N, 9.97. Found: C, 85.21; H, 4.45; N,
9.86%; IR (m(CN), cmꢀ1): 2230 w.
3.11. Synthesis of complexes S2, S3 and S4
Essentially the same procedure was used to obtain the
complexes, so a detailed description is given above only
for S1.
1
(M + H)+; H NMR (CDCl3): 7.34 (d, J = 8.3 Hz, 1 H,
NCCH), 7.59 (d, J = 8.5 Hz, 2 H, C6H4), 7.64 (d,
J = 8.5 Hz, 2 H, C6H4), 7.75 (dd, J = 2.3, 8.3 Hz, 1 H,
ClCCH), 8.53 (d, J = 2.2 Hz, 1 H, NCH); Anal. Calc.
for C14H7ClN2: C, 70.45; H, 2.96; N, 11.74. Found: C,
70.50; H, 2.99; N, 11.62%.
S2: Complex S2 was obtained as a red solid in 88%
yield. MS (FAB): m/e 1514.3 ((M ꢀ CO)+, 187Re; 81Br);
1H NMR (CD2Cl2): 7.00–8.10 (m, 24 H, aromatic), 7.62
(d, J = 8.1 Hz, 8 H, C6H4). 7.66 (d, J = 7.9 Hz, 2 H,
NCCHCH), 8.01 (d, J = 8.2 Hz, 2 H, NCCH), 8.60 (d,
J = 2.2 Hz, 2 H, NCH); Anal. Calc. for C66H38Br2
N6O6Re2: C, 51.37; H, 2.48; N, 5.45. Found: C, 51.02; H,
2.35; N, 5.56%; IR (m(CO), cmꢀ1): 2026 s, 1923 m, 1906
s; (m(CN), cmꢀ1): 2210 w.
3.9. Synthesis of 4-(6-iodopyridine-3-ylethynyl)benzonitrile
(4)
At 0 ꢁC, hydroiodide (2.26 ml, 6 mmol) was added drop-
wise, over 30 min, to 4-(6-chloropyridine-3-ylethynyl)ben-
zonitrile (3) (1.19 g, 5.0 mmol) in CH2Cl2 solvent (50 mL)
for 16 h, then heated to 60 ꢁC for 12 h. After cooling,
K2CO3 and Na2S2O5 were added to the flask. The mixture
was extracted into dichloromethane. The organic extract
was washed with brine solution, dried over anhydrous
MgSO4 and filtered. The volatiles were removed, and then
the residue were dissolved in ether which was collected by
filtration and the solvent were removed under vacuum.
Compound 4 was obtained as a yellow solid. in 82% yield.
S3: Complex S3 was obtained as dark red solid. in 67%
yield. MS (FAB): m/e 1415.4 ((M ꢀ CO)+, 187Re; 81Br),
1364.8 ((M ꢀ Br)+, 187Re; 81Br); 1H NMR (CD2Cl2):
7.00–7.42 (m, 20 H, aromatic), 7.66 (d, J = 8.2 Hz, 4 H,
C6H4), 7.74 (d, J = 8.2 Hz, 4 H,C6H4). 8.40 (s, 2 H,.
NCH). 8.52 (s,
2
H, NCH); Anal. Calc. for
C56H32Br2N8O6Re2: C, 46.54; H, 2.23; N, 7.75. Found:
C, 46.98; H, 2.02; N, 7.43%; IR (m(CO), cmꢀ1): 2024 s,
1924 m, 1890 s; (m(CN), cmꢀ1): 2209 w.
S4: Complex S4 contaminated with some impurities
were obtained as a orange solid. MS (FAB): m/e 1193.7
((M + H)+,187Re;81Br), 1113.8 ((M ꢀ Br)+, 187Re;81Br);
1H NMR (CD2Cl2): 7.50 (d, J = 8.4 Hz, 2 H,. NCCH),
7.80 (d, J = 8.3 Hz, 2 H,. NCHCCH), 8.29 (s, 2 H,
NCH); Anal. Calc. for C63H38BrN6O3Re: C, 63.42; H,
3.21; N, 7.04. Found: C, 65.06; H, 3.98; N, 6.32%; IR
(m(CO), cmꢀ1): 2024 s, 1909 m, 1892 s; (m(CN), cmꢀ1):
2213 w.
1
MS (FAB): m/e 331.0 (M + H)+; H NMR (CDCl3): 7.41
(dd, J = 2.4;8.3 Hz, 1 H, NCHCCH), 7.59 (d, J = 8.2 Hz,
2 H, C6H4), 7.63 (d, J = 8.2 Hz, 2 H, C6H4), 7.73 (d,
J = 8.2 Hz, 1 H, NCCH), 8.49 (d, J = 2.3 Hz, 1 H,
NCH); Anal. Calc. for C14H7IN2: C, 50.94; H, 2.14; N,
8.49. Found: C, 51.12; H, 2.17; N, 8.43%.
3.10. Synthesis of 4-(6-(naphthalen-1-yl-
phenylamino)pyrimidin-3-ylethynyl)benzonitrile (L4)
Acknowledgements
Naphthalenylphenylamine (0.658 g, 6.0 mmol), 4-(6-iod-
opyridin-3-ylethynyl)benzonitrile (4) (0.99 g, 3.0 mmol),
This work is partially supported by the Institute of
Chemistry, Academia Sinica, and Department of Chemistry,

982
P.-H. Huang et al. / Journal of Organometallic Chemistry 691 (2006) 975–982
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