Synthesis and characterization of new luminescent 1,10-phenanthroline- and pyridine-containing π-conjugated polymers. Their optical response to protic acid, Mn+, and solvents

Article abstract of DOI:10.1021/ma030280d

New π-conjugated polymers comprised of alternating 1,10-phenanthroline/1,4-didodecyl-oxybenzene, 1,10-phenanthroline/9.9-dioctylfluorene, or pyridine/1,4-dialkoxybenzene units were prepared by palladium(0)-catalyzed coupling reaction in 84-98% yields. The

Full text of DOI:10.1021/ma030280d

Macromolecules 2003, 36, 7513-7519
7513
Synthesis and Characterization of New Luminescent
1,10-Phenanthroline- and Pyridine-Containing π-Conjugated Polymers.
Their Optical Response to Protic Acid, Mn+, and Solvents
Ta k u m a Ya su d a a n d Ta k a k a zu Ya m a m oto*
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku, Yokohama 226-8503, J apan
Received May 19, 2003; Revised Manuscript Received August 2, 2003
ABSTRACT: New π-conjugated polymers comprised of alternating 1,10-phenanthroline/1,4-didodecyl-
oxybenzene, 1,10-phenanthroline/9,9-dioctylfluorene, or pyridine/1,4-dialkoxybenzene units were prepared
by palladium(0)-catalyzed coupling reaction in 84-98% yields. The derived polymers gave Mn of 5400-
8800 in GPC analysis, and they possessed good solubility in organic solvents and high thermal stability.
Electrochemical reduction (or n-doping) of the polymers proceeded with peaks in the range -2.3 to -2.6
V vs Ag+/Ag. The polymers were highly photoluminescent, and strong blue emission with the peak in the
range 412-434 nm was observed in solutions. The emission peak as well as the UV-vis absorption peak
of the polymer was influenced by the solvent polarity, protonation, and formation of metal complexes.
When the polymers were protonated with trifluoroacetic acid, a large red-shift (ca. 40-60 nm) of the
absorption peak was observed. The photoluminescent properties of the polymers were tuned by
coordination of the polymer with metal ions. Polymers with long side chains formed an ordered structure
in the solid state as judged from their XRD patterns.
In tr od u ction
polymer complex could be tuned from blue to red by the
kind of metal ion coordinated to the polymer.
Control of optical and electrical properties of π-con-
jugated polymers is important for designing photonic
and electronic devices using π-conjugated polymers.1
Among the π-conjugated polymers, those with electron-
withdrawing imine nitrogen(s) (CdN), for example,
We have expanded the study, and herein we report
the syntheses and chemical properties of a series of
luminescent π-conjugated polymers containing the 1,10-
phenanthroline or pyridine unit. The photophysical
properties of the polymers are highly responsive to
protonation and metal ion coordination. The polymers
are expected to be unique candidates for polymer-based
chemosensors.
Exp er im en ta l Section
are attracting interest, because they not only have the
electron-accepting ability but also are reactive for metal-
complex-forming reactions, N-protonation, N-oxidation,
and quaternization with RX, which can modify their
optical and electrical properties.2-4
Ma ter ia ls a n d Syn th eses. 2,7-Dibromo-9,9-dioctylfluorene
was donated from Adchemco Co. Ltd. 1,4-Dibromo-2,5-
dialkoxybenzene,8a,b 3,8-dibromo-1,10-phenanthroline (7),9
PdCl2(dppb) (dppb ) 1,4-bis(diphenylphosphino)butane),8c and
Pd(PPh3)48d were prepared according to the literature. Solvents
were dried, distilled, and stored under N2.
A variety of soluble π-conjugated copolymers consist-
ing of N-containing heterocycles have also been de-
veloped.3-7 Especially, luminescent properties of the
copolymers have received significant attention, owing
to their potential usability as electron-transporting
emitters in polymer light-emitting diodes (LEDs)6 and
as luminescent chemosensors.3,7 Wasielewski and co-
workers demonstrated that the UV-vis absorption and
emission behavior of a poly(p-phenylenevinylene) (PPV)
type polymer containing the 2,2′-bipyridyl unit changed
dramatically upon coordination with transition metal
ions.3a Recently, we briefly reported preparation of a
luminescent 1,10-phenanthroline-containing π-conju-
gated copolymer and its metal complexes with Zn(II),
Ir(III), and Eu(III).7 The color of emitted light from the
Synthetic procedures for the monomers and polymers and
data for their characterization are given in the Supporting
Information.
Mea su r em en ts. NMR and FT-IR spectra were recorded on
a J EOL EX-400 spectrometer and a J ASCO FT/IR-460 Plus
spectrometer, respectively. Elemental analyses were carried
out with a Yanagimoto Type MT-2 CHN autocorder. GPC
traces were obtained with a Toso HLC-8120 equipped with
polystyrene gel columns using THF as an eluent. Thermo-
gravimetric analysis (TGA) was performed on a Shimadzu
TGA-50. Cyclic voltammetry of cast films of the polymers on
Pt plates was performed in an acetonitrile solution of
[(C2H5)4N]BF4 (0.10 M) with a Pt counter electrode and an Ag+/
Ag reference electrode by using a Toyo Technica Solartron SI
1287 electrochemical interface. The cast film was prepared
from a dilute chloroform solution. UV-vis absorption and
photoluminescence (PL) spectra were measured with
a
Shimadzu UV-3100 and a Hitachi F-4010 spectrometer, re-
spectively. Powder X-ray diffraction (XRD) patterns were
obtained using a Rigaku RINT2100 diffractmeter with Cu KR
(1.54 Å) radiation.
10.1021/ma030280d CCC: $25.00 © 2003 American Chemical Society
Published on Web 09/13/2003

7514 Yasuda and Yamamoto
Macromolecules, Vol. 36, No. 20, 2003
Sch em e 1. Syn th etic Rou tes of th e Mon om er sa
a
(i) C12H25Br, KOH, DMSO, 140 °C; (ii) Br2, CCl4, room temperature; (iii) (1) Mg, THF, reflux; (2) 2,5-dibromopyridine,
PdCl2(dppb) (dppb ) 1,4-bis(diphenylphosphino)butane), room temperature; (iv) LiI, 2,4,6-collidine, 150 °C.
Sch em e 2. Syn th esis of th e P olym er sa
a
(i) Pd(PPh3)4, Na2CO3 or NaHCO3, THF/H2O, 60 °C.
Resu lts a n d Discu ssion
and 6 was carried out under conditions similar to those
applied for the monomer 3.
Syn t h esis. The synthetic routes of the monomers
are outlined in Scheme 1. 1,4-Dibromo-2-dodecyloxy-5-
methoxybenzene (2) was readily prepared by the bro-
mination of 1-dodecyloxy-4-methoxybenzene (1) with
Br2. 1,4-Bis[2-(5-bromopyridyl)]-2-dodecyloxy-5-meth-
oxybenzene (3) was synthesized by a palladium(II)-
catalyzed coupling reaction of the di-Grignard reagent
of 2 with 2,5-dibromopyridine. This reaction occurred
chemospecifically at the 2-position of 2,5-dibromo-
pyridine. Subsequent treatment of 3 with LiI in 2,4,6-
collidine gave the monomer 4 with a OH group. Syn-
thesis of the pyridine-containing dibromo monomers 5
The new copolymers were prepared according to
Scheme 2. The polymerizations in all cases are based
on palladium(0)-catalyzed Suzuki-coupling reactions,
which were carried out using monomers in a mixture
of THF and aqueous Na2CO3 or NaHCO3 containing 3
mol % Pd(PPh3)4 as the catalyst at 60 °C under N2. After
purification and vacuum-drying, all the polymers were
obtained with satisfactory yields (84-98%).
Ch a r a cter iza tion of th e P olym er s. Results of the
polymerization are summarized in Table 1. The obtained
polymers showed good solubility in common organic
solvents such as chloroform, THF, and toluene. As

Macromolecules, Vol. 36, No. 20, 2003
New Luminescent π-Conjugated Polymers 7515
Ta ble 1. P r ep a r a tion of th e P olym er s
a
a
polymer
yield, %
color
Mn
Mw/Mn
Td,b °C
P(PhenPh)
P(PhenFl)
P(PyPh)-1
P(PyPh)-2
P(PyPh)-3
P(PyPh)-4
97
84
98
96
95
87
yellow
yellow
green
orange
yellow
green
7000
6700
8800
5900
8500
5400
2.0
1.8
1.2
1.9
1.2
1.3
384
417
412
389
418
419
a
Estimated from GPC (eluent: THF, polystyrene standards).
5% weight-loss temperature measured by TGA under N2 with a
b
heating rate of 10 °C min-1
.
F igu r e 2. Cyclic voltammogram of a film of P(PhenPh) on a
Pt plate in an acetonitrile solution of [(C2H5)4N]BF4 (0.10 M)
under N2. The sweep rate is 30 mV s-1
.
Ta ble 2. Electr och em ica l a n d Op tica l Da ta of th e
P olym er s
optical data
redox potentiala
(V vs Ag+/Ag)
THF solution
cast film
Φc λmax λEM
(%) (nm) (nm)
λmax
(nm)
λEM
(nm)
polymer
Ered
Eox
P(PhenPh) -2.41
1.12
1.31
1.09
1.17
1.06
1.02
380 434
54 385 524
P(PhenFl)
P(PyPh)-1
P(PyPh)-2
P(PyPh)-3
P(PyPh)-4
-2.36
-2.60
b
-2.59
-2.48
384 412, 435d 60 389 527
380 428
401 581
380 425
368 429
91 388 434
<1 413
b
87 385 508
67 375 439
a
Measured by cyclic voltammetry in an acetonitrile solution of
F igu r e 1. 1H NMR spectra of (a) P(PhenPh), (b) P(PhenFl),
(c) P(PyPh)-1, and (d) P(PyPh)-2 in CDCl3. The peaks with the
* are due to solvent impurities.
[(C2H5)4N]BF4 (0.10 M). Ered and Eox stand for reduction (n-doping)
b
peak and oxidation (p-doping) peak potentials, respectively. Not
clearly observable. c PL quantum yield calculated by comparing
with the standard of quinine sulfate (ca. 10-5 M solution in 0.5 M
d
H2SO4, having a quantum yield of 54.6%).19 Subpeak.
shown in Table 1, the number-average molecular weights
(Mn) of the polymers are estimated to be 5400-8800
(polystyrene standards) with the polydispersity index
(Mw/Mn) of 1.2-2.0 by GPC measurement (eluent )
THF). The results agree with the data obtained from
the elemental analysis.
The polymers had good thermal stability under N2.
The first major weight loss of the polymers started
around 360-400 °C, and a residual weight of about 40-
60% was observed at 900 °C. Data of the 5% weight-
loss temperatures (Td) of the polymers are included in
Table 1.
1
Figure 1 depicts the H NMR spectra of P(PhenPh),
P(PhenFl), P(PyPh)-1, and -2 in CDCl3; assignment of
1
Red ox Beh a vior . Figure 2 shows the cyclic voltam-
mogram (CV) for a cast film of P(PhenPh) on a Pt plate
in an acetonitrile solution of [(C2H5)4N]BF4 (0.10 M).
Electrochemical reduction (n-doping) starts at about
-2.1 V with a peak at Ered ) -2.41 V vs Ag+/Ag, and
the corresponding oxidation (n-dedoping) peak is ob-
served at -2.27 V vs Ag+/Ag. These types of n-doping
and n-dedoping couples have been observed with π-con-
jugated polymers having electron-accepting units such
as a pyridine unit.2-6 The electrochemical process was
accompanied by an obvious color change from yellow in
the neutral state to dark brown in the n-doped state.
the peaks is made by comparing the H NMR spectra
with those of the corresponding monomers. The four
peaks of P(PhenPh) at δ 9.50, 8.50, 7.87, and 7.00 are
due to protons of 1,10-phenanthroline and phenylene
rings, as assigned in Figure 1a. The peaks of the
alkyl side chains are observed in the region of δ 4.09-
0.87, and the peak areas agree with the structure of
P(PhenPh).
1H NMR spectra of P(PyPh)-1 and -2 (Figure 1c and
d) show some difference due to the difference in the
substituents. The -OCH3 peak of P(PyPh)-1 appears at
δ 4.01, which was overlapped with the -OCH2 peak,
whereas the peak due to the phenolic -OH group of
P(PyPh)-2 is found at a considerably low magnetic field
of δ 13.9. The peak position of the -OH group suggests
the occurrence of an intramolecular hydrogen bonding
to the neighboring pyridyl nitrogen; such hydrogen
In the oxidative region, a peak is observed at Eox
)
1.12 V vs Ag+/Ag, which is assigned to oxidation
(p-doping) of the phenylene group; a similar oxidation
potential of 1.0 V vs Ag+/Ag has been reported for poly-
(p-phenylene).11a However, its reduction (p-dedoping)
peak was not clearly observed. Presumably, the dopant
BF4- seems to be trapped by coordination with the OR
groups, and the strong interaction between the OR
1
bonding to give the H NMR peak near the position has
been reported for compounds with a similar local
structure.10 IR spectra of the polymers resembled those
of the monomers; however, the ν(C-Br) absorption peak
of the dibromo monomers near 1100 cm-1 was not
observable after the polymerization.
-
groups and the BF4 dopant may be the reason for the
irreversibility of the p-doping. The electrochemical redox
data of the polymers are summarized in Table 2.

7516 Yasuda and Yamamoto
Macromolecules, Vol. 36, No. 20, 2003
F igu r e 3. UV-vis absorption spectra of (a) P(PhenPh) (s),
(b) P(PyPh)-1 (- - -), and (c) P(PyPh)-2 (- - -) in THF at room
temperature.
F igu r e 4. PL spectra of P(PhenPh) in various solvents. The
UV-vis a n d P h otolu m in escen ce (P L) Da ta . Fig-
ure 3 depicts UV-vis absorption spectra of P(PhenPh),
P(PyPh)-1, and -2 in THF. P(PhenPh) and P(PyPh)-1
exhibit the absorption peak (λmax) at 380 nm, which is
assigned to the π-π* absorption peak; the λmax position
is comparable to those of PPy,2a poly(1,10-phenan-
throline),2c poly(p-phenylene),11a,b and poly(fluorene)s.11c
The λmax position of P(PyPh)-2 (Figure 3c) is shifted by
about 20 nm to a longer wavelength, compared with that
of P(PyPh)-1. This bathochromic shift may be due to
formation of an intramolecular hydrogen bond between
the OH group and the pyridyl nitrogen atom, which will
assist the coplanarization of the polymer chain, as
previously proposed for disk-shaped compounds.10 The
UV-vis absorption and photoluminescence (PL) data of
the polymers in solution and in film are listed in Table
2. The λmax of the polymers in film showed a small red-
shift (by ca. 5-10 nm) from that in solution.
inset shows plots of the energy of the UV-vis absorption (λmax
and PL (λEM) against the ET(30) value of the solvent.
)
not much affected by the solvent surrounding the
polymer molecule.
Plots of the emission energy versus the ET(30) value,13
which is used as a measure of polarity of solvent, give
a roughly straight line shown in the inset of Figure 4.
This solvent effect on PL is considered to be due to
stabilization of a polar excited state by solvation; the
photoexcited polymer molecule seems to be stabil-
ized by the interaction with the solvent molecules.13,14
P(PhenPh) consists of an electron-accepting 1,10-
phenanthroline unit and an electron-donating dialkoxy-
benzene unit, and it is considered to have an intra-
molecular alternating charge transfer (CT) structure.
Photoexcitation will cause migration of an electron from
the dialkoxybenzene unit to the 1,10-phenanthroline
unit to increase the intramolecular polarization, and
stabilization of this polar excited state by the polar
solvent accounts for the larger Stokes shift in polar
solvents. A similar solvent effect on PL was also
observed for P(PhenFl); however, P(PyPh)-1 did not
clearly show such a solvatochromism. The pyridine unit
would have less electron-accepting property than the
1,10-phenanthroline unit.
The polymers are highly photoluminescent both in
solution and in film. The PL quantum yields (Φ in Table
2) of the polymers, except for P(PyPh)-2, in THF were
found to be very high (Φ ) 54-91%). The PL peak, λEM
,
position of the polymers in THF agreed with the onset
position of the absorption band, as usually observed with
π-conjugated polymers in solutions. However, the PL
behavior of P(PhenPh), P(PhenFl), and P(PyPh)-3 in
film was quite different from that in the solution. The
λEM in film shifts by about 80-120 nm toward longer
wavelength with broadening of the peak. This seems to
be due to formation of the excimer-like adduct between
the photoexcited polymer molecule and the polymer
molecule in the ground state.
Resp on se to P r otic Acid a n d Na OH. The polymers
are considered to react with protic acids and metal ions
M
n+, and expected reactions under various conditions
are illustrated in Scheme 3.
Actually, the polymers were effectively protonated
with trifluoroacetic acid (TFA). As shown in Figure 5,
addition of TFA (from 0 to 4.0 × 10-3 M) to a solution
of P(PhenPh) (2.0 × 10-5 M) in chloroform leads to a
considerably large red-shift of the λmax position from 385
to 440 nm. The PL intensity is, on the other hand,
strongly decreased due to the protonation of the imine
nitrogen. Other polymers also gave similar changes (e.g.,
the data are shown in the Supporting Information).
In the case of P(PyPh)-2 having the acidic OH group,
it responded to sodium hydroxide. As exhibited in Figure
6, the λmax position of P(PyPh)-2 (2.0 × 10-5 M) in THF-
methanol (25:1) shifts to a longer wavelength with
increase in the concentration of NaOH, and the PL
intensity is strongly enhanced (by greater than 10 times,
compared with the neutral state). Similar optical changes
of π-conjugated polymers having the phenolic OH group
have been reported.15
As presented in Table 2 and described above, the PL
quantum yield of P(PyPh)-2 is very low (Φ < 1%).
P(PyPh)-2 possesses the mobile-H in the OH group, and
it may bring about excited-state intramolecular proton
transfer (ESIPT)12 from the acidic phenol to the basic
imine nitrogen of the pyridine ring, thus providing
nonradiative decay pathway(s) to decrease the quantum
yield.
Effect of Solven t P ola r ity on th e Op tica l P r op -
er ties. Figure 4 shows the PL spectra of P(PhenPh) in
various solvents. As seen in Figure 4, the λEM position
of P(PhenPh) shifts by about 40 nm to a longer wave-
length and the PL intensity gradually decreased with
increase in polarity of the solvent, from less polar
toluene to highly polar NMP (N-methyl-2-pyrrolidi-
none). In contrast, the λmax position of P(PhenPh) was
slightly influenced by polarity of solvent, indicating that
the electronic state of P(PhenPh) in the ground state is
R esp on se t o
P(PyPh)-2 are expected to serve as metal ion receptors
M
n +. P(PhenPh), P(PhenFl), and

Macromolecules, Vol. 36, No. 20, 2003
New Luminescent π-Conjugated Polymers 7517
Sch em e 3. Rea ction s of th e P olym er s u n d er Va r iou s Con d ition s
(cf. Scheme 3). Table 3 summarizes changes of the UV-
vis and PL data for P(PhenPh), P(PhenFl), and P(PyPh)-2
observed upon addition of metal ions (20 mol per 1 mol
-4, however, showed much less ionochromic effect by the
addition of metal ions.
It was reported that the 2,2′-bipyridyl-containing
π-conjugated polymers serve as an excellent chemo-
sensor of metal ions.3a,b These polymers, however, did
not respond much to alkaline and alkaline earth metal
ions. P(PhenPh), P(PhenFl), and P(PyPh)-2 indicated
good response to a large variety of metal ions including
alkaline and alkaline earth metal ions, presumably due
to the high coordinating ability of the 1,10-phenanthro-
line and the pyridine-phenol blocks. 1,10-Phenanthro-
line possesses an exceptionally high selectivity and
binding constant for Li+ among alkaline metal ions,17
and it forms complexes with divalent alkaline earth
of the repeating unit).16 As seen in Table 3, Li+, Mg2+
,
Ca2+, Al3+, Zn2+, and La3+ cause only a small shift of
the λmax position. For these metal ions, PL was clearly
observed with a shift of λEM position, which depends on
the kind of metal ion.
Transition metal ions such as Co2+, Ni2+, Cu2+, and
Pd2+, on the other hand, led to a large red-shift of λmax
by about 20-50 nm and complete quenching of PL. This
quenching effect of PL may be related to an energy
transfer from the photoactivated π-conjugated poly-
mer main chain to the metal complex part.3a Figure 7
is a photograph showing the emission of light from
P(PhenFl) in solutions with and without metal ions
under UV irradiation. It is found that the color of the
emitted light can be tuned over a wide range of color
by changing the kind of metal ion. P(PyPh)-1, -3, and
metal ions such as Mg2+ and Ca2+ 17
To our knowledge,
.
there is no precedent that 1,10-phenanthroline- and
F igu r e 6. Changes in the absorption spectrum of P(PyPh)-2
(2.0 × 10-5 M (repeating unit)) in THF-methanol (25:1) at
various concentrations of NaOH: [NaOH] ) 0, 1.5 × 10-5, 2.5
× 10-4, 5.0 × 10-4, and 2.0 × 10-3 M. The inset shows the PL
spectrum of the polymer solution at [NaOH] ) 2.0 × 10-3 M.
F igu r e 5. Changes in (a) UV-vis absorption and (b) PL
spectra of P(PhenPh) (2.0 × 10-5 M (repeating unit)) in
chloroform at various concentrations of TFA: [TFA] ) 0, 2.0
× 10-5, 4.0 × 10-5, 2.0 × 10-4, 5.0 × 10-4, and 4.0 × 10-3 M.

7518 Yasuda and Yamamoto
Macromolecules, Vol. 36, No. 20, 2003
Ta ble 3. UV-vis a n d P L Resp on se of th e P olym er s to
) 24.8-17.2 Å) seem to correspond to a distance
between the polymer main chains separated by the long
alkoxy side chains, as often observed with other π-con-
jugated polymers having such long side chains. The
peak at d ) 4.2 Å is considered to be originated from
the side-to-side distance between loosely packed alkoxy
chains. The alkyl group has a diameter of about 5 Å,
and packing of alkyl groups often gives a peak in this
region.18 Thus, the polymers are considered to form an
ordered structure in the solid state due to the crystal-
linity of the long alkoxy side chain.
As shown in Table 2, the UV-vis peaks of the three
polymers in films are shifted by 5-12 nm to a longer
wavelength from those in THF, and this may be due to
intermolecular interaction between the polymer mol-
ecules in the ordered structure. However, the degree of
the shift to a longer wavelength is much smaller than
that observed with five-membered ring π-conjugated
polymers such as regioregular head-to-tail type poly(3-
alkylthiophene), which forms a π-stacked structure.20
Formation of an ordered structure is considered to be
disadvantageous in electroluminescence; however, it
seems to be advantageous for higher mobility of carrier
in the polymer film and large third-order optical non-
linear susceptibility.21
Mn + a
P(PhenPh)
P(PhenFl)
P(PyPh)-2b
c
c
c
metal
ion
λmax
(nm)
λEM
λmax
(nm)
λEM
λmax
(nm)
λEM
(nm)
(nm)
(nm)
ion-free 385 445 (s)
384 412, 434 (s) 415d 594 (w)d
Li+
395 506 (s)
395 519 (s)
403 527 (s)
387
399
409
437 (s) 408
468 (s) 410
476 (s) 403
565 (s) 401
480 (s) 403
583 (w)
545 (m)
537 (m)
(q)
570 (m)
(q)
Mg2+
Ca2+
Al3+
Zn2+
Co2+
Ni2+
Cu2+
Pd2+
La3+
419 554 (m) 428
418 540 (s)
417
415
410
411
423
411
404
420
437
(q)
(q)
(q)
(q)
(q)
e
(q) 433
(q) 431
(q)
(q)
(q)
(q)
e
411 521 (m) 413
471 (w) 398
537 (w)
a
Conditions: polymer (2.0 × 10-5 M (repeating unit)) and metal
ion (4.0 × 10-4 M) in THF-methanol (25:1). The following metal
salts were used: LiCl, MgCl2, CaCl2, Al2(SO4)3, ZnCl2, CoCl2,
b
NiCl2, CuCl2, PdCl2, and LaCl3. In the presence of NaOH (2.0 ×
10-3 M) as a base. Without the base, no observable changes were
detected on addition of Mn+ c Intensity of the emitted light given
.
in parentheses: s, strong; m, medium; w, weak; q, very weak
d
(quenched). In THF without methanol, P(PyPh)-2 gave the λmax
at 401 nm as shown by curve c in Figure 3. e The absorption peak
of the polymer was not clearly observed.
Con clu sion s
New luminescent π-conjugated polymers consisting of
the 1,10-phenanthroline or pyridine unit have been
synthesized. Cyclic voltammetry revealed electron-
accepting properties of the polymers. The obtained
polymers were soluble in organic solvents, and the
solutions emitted intense blue PL. The polymers re-
sponded well to H+ and Mn+ with changes in UV-vis
and PL spectra.
F igu r e 7. Emission of light from P(PhenFl) in the presence
of metal ions in THF-methanol. This photograph was taken
under irradiation with light at 365 nm.
Ack n ow led gm en t. This research was partly sup-
ported by the 21st Century COE program.
Su p p or tin g In for m a tion Ava ila ble: Synthetic proce-
dures and spectroscopic and analytical data of the monomers
and polymers; UV-vis and PL spectra of P(PyPh)-1 in chloro-
form at various concentrations of TFA; and UV-vis spectra
of P(PhenPh) in THF-methanol (25:1) at various concentra-
tions of NiCl2 (PDF). This material is available free of charge
via the Internet at http://pubs.acs.org.
Refer en ces a n d Notes
(1) (a) Kraft, A.; Grimsdale, A. C.; Holmes, A. B. Angew. Chem.,
Int. Ed. 1998, 37, 402. (b) Friend, R. H.; Gymer, R. W.;
Holmes, A. B.; Burroughes, J . H.; Marks, R. N.; Taliani, C.;
Bradley, D. D. C.; Dos Santos, D. A.; Bre´das, J . L.; Lo¨gdlund,
M.; Salaneck, W. R. Nature 1999, 397, 121. (c) Goldenberg,
L. M.; Bryce, M. R.; Petty, M. C. J . Mater. Chem. 1999, 9,
1957. (d) Tour, J . M. Acc. Chem. Res. 2000, 33, 791. (e)
Kingsborough, R. P.; Swager, T. M. Prog. Inorg. Chem. 1999,
48, 123.
(2) (a) Yamamoto, T.; Maruyama, T.; Zhou, Z.-H.; Ito, T.; Fukuda,
T.; Yoneda, Y.; Begum, F.; Ikeda, T.; Sasaki, S.; Takezoe, H.;
Fukuda, A.; Kubota, K. J . Am. Chem. Soc. 1994, 116, 4832.
(b) Maruyama, T.; Kubota, K.; Yamamoto, T. Macromolecules
1993, 26, 4055. (c) Saitoh, Y.; Yamamoto, T. Chem. Lett. 1995,
785. (d) Hayashida, N.; Yamamoto, T. Bull. Chem. Soc. J pn.
1999, 72, 1153.
(3) (a) Wang, B.; Wasielewski, M. R. J . Am. Chem. Soc. 1997,
119, 12. (b) Liu, B.; Yu, W.-L.; Pei, J .; Liu, S.-Y.; Lai, Y.-H.;
Huang, W. Macromolecules 2001, 34, 7932. (c) Bangcuyo, C.
G.; Rampey-Vaughn, M. E.; Quan, L. T.; Angel, S. M.; Smith,
M. D.; Bunz, U. H. F. Macromolecules 2002, 35, 1563. (d)
Crawford, K. B.; Goldfinger, M. B.; Swager, T. M. J . Am.
Chem. Soc. 1998, 120, 5187.
F igu r e 8. Powder X-ray diffraction patterns of (a) P(PhenPh),
(b) P(PyPh)-1, and (c) P(PyPh)-2.
pyridine-containing π-conjugated polymers show such
a highly sensitive ionochromic effect. The polymers are
expected to serve as new polymer-based metal ion
sensors.
X-r a y Diffr a ction . Figure 8 exhibits powder X-ray
diffraction (XRD) patterns of P(PhenPh), P(PyPh)-1, and
P(PyPh)-2. The strong peaks in the low-angle region (d

Macromolecules, Vol. 36, No. 20, 2003
New Luminescent π-Conjugated Polymers 7519
(4) (a) Yamamoto, T.; Lee, B.-L.; Hayashi, H.; Saito, N.; Maruya-
ma, T. Polymer 1997, 38, 4233. (b) Yamamoto, T.; Yoneda,
Y.; Kizu, K. Macromol. Rapid Commun. 1995, 16, 549.
(5) (a) Peng, Z.; Gharavi, A. R.; Yu, L. J . Am. Chem. Soc. 1997,
119, 4622. (b) Yamamoto, T.; Zhou, Z.-H.; Kanbara, T.;
Shimura, M.; Kizu, K.; Maruyama, T.; Nakamura, Y.; Fuku-
da, T.; Lee, B.-L.; Ooba, N.; Tomaru, S.; Kurihara, T.; Kaino,
T.; Kubota, K.; Sasaki, S. J . Am. Chem. Soc. 1996, 118, 10389.
(6) (a) Tanzola, C. J .; Alam, M. M.; J enekhe, S. A. Adv. Mater.
2002, 14, 1086. (b) Ng, S.-C.; Lu, H.-F.; Chan, H. S. O.; Fujii,
A.; Laga, T.; Yoshino, K. Macromolecules 2001, 34, 6895. (c)
Wang, C.; Kikitziraki, M.; MacBride, J . A. H.; Bryce, M. R.;
Horsburgh, L. E.; Sheridan, A. K.; Monkman, A. P.; Samuel,
I. D. W. Adv. Mater. 2000, 12, 217.
(7) Yasuda, T.; Yamaguchi, I.; Yamamoto, T. Adv. Mater. 2003,
15, 293.
(8) (a) Vahlenkamp, T.; Wegner, G. Macromol. Chem. Phys. 1994,
195, 1933. (b) Ruiz, J . P.; Dharia, J . R.; Reynolds, J . R.
Macromolecules 1992, 25, 849. (c) Guerrieri, F.; Salermo, G.
J . Organomet. Chem. 1976, 114, 339. (d) Coulton, D. R. Inorg.
Synth. 1972, 13, 121.
(14) Silva, A. P.; Gunaratne, H. Q. N.; Gunnlaugsson, T.; Huxley,
A. J . M.; McCoy, C. P.; Rademacher, J . T.; Rice, T. E. Chem.
Rev. 1997, 97, 1515.
(15) (a) Remmers, M.; Schulze, M.; Wegner, G. Macromol. Chem.
1996, 17, 239. (b) Hayashi, H.; Yamamoto, T. Macromolecules
1998, 31, 6063.
(16) A much smaller amount of the metal ion also gave similar
UV-vis and PL changes. For instance, 1 mol of Ni2+ per
repeating unit caused almost complete quenching of PL of
P(PhenPh), as shown in the Supporting Information.
(17) (a) Sugihara, H.; Hiratani, K. Coord. Chem. Rev. 1996, 148,
285. (b) Satterfield, M.; Brodbelt, J . S. Inorg. Chem. 2001,
40, 5393.
(18) (a) J ordan, E. F., J r.; Feldeisen, D. W.; Wrigley, A. N. J .
Polym. Sci.: Part A-1 1971, 9, 1835. (b) Hsieh, H. W.; Post,
B.; Morawetz, H. J . Polym. Sci.: Polym. Phys. Ed. 1976, 14,
1241. (c) Miller, R. L. In High Polymers, Vol. XX; Mark, H.,
Flory, P. J ., Marvel, C. S., Melville, H. W., Eds.; Inter-
science: New York, 1965; p 585. (d) Cross section of the alkyl
chain ) about 18 Å2.18c
(19) Melhuish, W. H. J . Phys. Chem. 1961, 65, 229.
(20) (a) McCullough, R. D.; Tristram-Nagle, S.; Williams, S. P.;
Lowe, R. D.; J ayaraman, M. J . Am. Chem. Soc. 1993, 115,
4910. (b) Chen, T.-A.; Wu, X.; Rieke, R. D. J . Am. Chem. Soc.
1995, 117, 233.
(21) (a) Nalwa, H. S., Ed. Handbook of Organic Conductive
Molecules and Polymers; J ohn Wiley: Chichester, 1997. (b)
Sirringhaus, H.; Brown, P. J .; Friend, R. H.; Nielsen, M. M.;
Bechgaard, K.; Langeveld-Boss, B. M. W.; Spiering, J . H.;
J anssen, R. A. J .; Meijer, E. W.; Herwig, P.; de Leeuw, D. M.
Nature 1999, 401, 685. (c) Yamamoto, T. Synlett 2003, 425.
(9) Saitoh, Y.; Koizumi, T.; Osakada, K.; Yamamoto, T. Can. J .
Chem. 1997, 75, 1336.
(10) Shu, W.; Valiyaveettil, S. Chem. Commun. 2002, 1350.
(11) (a) Fauvarque, J .-F.; Petit, M.-A.; Digua, A.; Froyer, G.
Makromol. Chem. 1987, 188, 1833. (b) Aeiyach, S.; Soubiran,
P.; Lacaze, P. C.; Froyer, G.; Pelous, Y. Synth. Met. 1989,
32, 103. (c) Scherf, U.; List, E. J . W. Adv. Mater. 2002, 14,
477.
(12) (a) Kim, S.; Chang, W.; Park, S. Y. Macromolecules 2002, 35,
6064. (b) Potter, C. A. S.; Brown, R. G.; Vollmer, F.; Rettig,
W. J . Chem. Soc., Faraday Trans. 1994, 90, 59.
(13) Reichardt, C. Chem. Rev. 1994, 94, 2319.
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