A novel low-bandgap conjugated polymer based on Ru(II) bis(acetylide) complex and BODIPY moieties

Article abstract of DOI:10.1002/pola.27166

A novel conjugated polymer P-1 incorporating Ru(II) bis(acetylide) complex and borondipyrromethene (BODIPY) moieties in the main chain was synthesized by Pd-catalyzed Sonogashira coupling reaction of diethynyl substituted BODIPY derivative (M-1) and Ru(II) bis(acetylide) complex (M-2), and the reference polymer P-2 was obtained from the same method as preparation of P-1. Compared with P-2, Ru(II)-containing polymer P-1 shows low-bandgap as 0.87 eV from cyclic voltammetry, and obvious redshifts in both UV-vis absorption and fluorescence spectra.

Full text of DOI:10.1002/pola.27166

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A Novel Low-Bandgap Conjugated Polymer Based on Ru(II) Bis(acetylide)
Complex and BODIPY Moieties
Shuwei Zhang, Yuan Sheng, Guo Wei, Yiwu Quan, Yixiang Cheng, Chengjian Zhu
Key Lab of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093,
China
Correspondence to: Y. Cheng (E-mail: yxcheng@nju.edu.cn) or C. Zhu (E-mail: cjzhu@nju.edu.cn)
Received 13 November 2013; accepted 11 March 2014; published online 1 April 2014
DOI: 10.1002/pola.27166
ABSTRACT: A novel conjugated polymer P-1 incorporating Ru(II)
bis(acetylide) complex and borondipyrromethene (BODIPY)
moieties in the main chain was synthesized by Pd-catalyzed
Sonogashira coupling reaction of diethynyl substituted BODIPY
derivative (M-1) and Ru(II) bis(acetylide) complex (M-2), and
the reference polymer P-2 was obtained from the same method
as preparation of P-1. Compared with P-2, Ru(II)-containing
polymer P-1 shows low-bandgap as 0.87 eV from cyclic voltam-
metry, and obvious redshifts in both UV–vis absorption and
C
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fluorescence spectra.
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KEYWORDS: BODIPY; conjugated polymers; electrochemistry;
heteroatom-containing polymers; low-bandgap; Ru(II) bis(ace-
tylide) complex
BODIPY-based CPs have been extensively studied for fluores-
cent sensors, dye-sensitized solar cells, and so on.25–28
Recently, several groups have researched BODIPY-based tran-
sition-metal complexes.29–31 However, to the best of our
knowledge, all of them are based on small molecules. There
has been no report on BODIPY-based CPs containing
transition-metal complexes.
INTRODUCTION Conjugated polymers (CPs) containing tran-
sition metals in the backbone have been studied extensively
for chemical sensors, electroluminescent devices, field-effect
transistors, solar cells, and so on, due to their special redox,
magnetic, and electrical properties.1–6 For instance, some
CPs incorporating Ir(III) and Ru(II) complexes show efficient
phosphorescent emission and could be used for organic
light-emitting diodes (OLED).7–10 Among these materials,
rigid-rod organometallic CPs, which contain transition metal
fragments linked with acetylenic chromophores in the poly-
mer main backbone, have attracted increasing interests,
because this special structure could result in beneficial influ-
ence on extended d–p conjugation and electronic properties
of the CPs.11–13 Wong et al. reported bulk heterojunction
(BHJ) solar cells incorporating thiophene-based polyplati-
nynes with power conversion efficiencies (PCEs) as high as
4.1%.14 Besides platinum complexes, other transition-metal
complexes, especially Ru(II) complexes, also exhibit special
optical and electrical properties due to the rich electronic
structures of their metal centers and organic ligands.15–17
Some of them have been introduced into the polymer back-
bones to realize the desirable optoelectronic materials.18,19
Herein, to investigate a kind of novel materials with low-
bandgaps and broad absorption in visible to near-infrared
regions, we designed and synthesized a BODIPY-based and
Ru(II) complex-containing CP P-1, which could effectively
tune the electronical properties by introduction of Ru(II)
complex moieties in the polymer main backbone. As
expected, compared with the reference polymer P-2 without
Ru(II) complex moieties, the bandgap of P-1 can be greatly
decreased from 1.51 to 0.87 eV.
EXPERIMENTAL
Materials and Measurements
All solvents and reagents were commercially available and
analytical reagent grade. THF and Et3N were distilled from
sodium in the presence of benzophenone. NMR spectra were
obtained from Bruker Avance 300 spectrometer with 300
Over the past decades, 4,4-difluoro-4-bora-3a,4a-diaza-s-
indacene (BODIPY) and its derivatives have become one of
the versatile fluorophores due to their good optical proper-
ties, such as high absorption coefficients, narrow absorption
band, and high quantum yields, and so forth.20–24 And
1
MHz for H NMR and 75 MHz for 13C NMR, Bruker DRX 400
spectrometer with 162 MHz for 31P NMR, and Bruker DRX
500 spectrometer with 160 MHz for 11B NMR. UV–vis spec-
tra were obtained from
a Perkin–Elmer Lambda 25
Additional Supporting Information may be found in the online version of this article.
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spectrometer. Fluorescence spectra were obtained from a RF-
5301PC spectrometer. Time-resolved fluorescence decays
were obtained from HORIBA JOBIN YVON Tem Pro-01 life-
time fluorescence spectroscopy. Electrospray ionization mass
spectra (ESI-MS) were obtained from a Thermo Finnigan
LCQ Fleet system. FTIR spectra were measured on a Nexus
870 FTIR spectrometer. Elemental analyses were performed
on an Elementar Vario MICRO analyzer. Thermogravimetric
analyses (TGA) were obtained from a Perkin–Elmer Pyris-1
instrument under N2 atmosphere. Molecular weight was
determined by gel permeation chromatography (GPC) with a
Waters 244 HPLC pump, and THF was used as solvent rela-
tive to polystyrene standards.
P4Ru: C 61.50, H 5.41; Found: C 62.05; H 5.49; MS (ESI):
m/z calcd for
1640.50.
C
84H88I2O4P4Ru: 1640.28 [M1]; found:
Synthesis of M-3
A mixture of 4 (500 mg, 1.34 mmol), N,N,N0,N0-tetramethyle-
thylenediamine (TMEDA) (0.05 mL, 0.27 mmol), CuI (12.8
mg, 0.07 mmol), and Et3N (0.56 mL, 4.02 mmol) were added
to acetone (15 mL). The reaction was stirred for 16 h at
room temperature. The product was formed as precipitation.
After filtration, the solid was dissolved in CH2Cl2 (100 mL).
And the organic solution was washed with water and brine,
dried over anhydrous Na2SO4. After filtration, the solvent
was removed to afford M-3 (320 mg, 64.3%) as a yellow
1
solid. H NMR (300 MHz, CDCl3): d 7.31 (s, 2H), 6.90 (s, 2H),
Synthesis of M-1
4.02–3.94 (m, 8H), 1.86–1.77 (m, 8H), 1.62–1.48 (m, 8H),
1.03–0.98 (m, 12H); 13C NMR(75 MHz, CDCl3): d 155.5,
151.7, 123.8, 116.5, 112.1, 89.0, 78.7, 78.4, 69.7, 69.6, 31.1,
19.2, 19.1, 13.7; MS (ESI): m/z calcd for C32H40I2O4: 765.09
[M1Na1]; found: 765.05.
A mixture of 2 (1.0 g, 1.42 mmol), Pd(PPh3)2Cl2 (49.8 mg,
5% mmol), CuI (27.0 mg, 10% mmol) were dissolved in
anhydrous THF (20 mL), then trimethylsilylacetylene (726
mg, 4.26 mmol) in THF (5 mL) and Et3N (5 mL) was added
under N2 atmosphere. The reaction mixture was stirred for
24 h at 50 ꢀC. Then the solvent was removed under
reduced pressure to afford the residue. The residue was
dissolved in MeOH (50 mL), then K2CO3 (0.58 g, 4.20
mmol) was added. The reaction mixture was stirred for 3 h
at room temperature. Then the reaction mixture was fil-
trated, and the filtrate was concentrated to afford the resi-
due. The residue was dissolved in CH2Cl2 (60 mL), and the
organic solution was washed with water and brine, then
dried over anhydrous Na2SO4. After filtration, the solvent
was removed to afford crude product. The crude product
was purified by silica gel chromatography (petroleum
ether/ethyl acetate, vol/vol, 10/ 1) to afford M-1 (0.52 g,
72.6%) as a deep red solid. 1H NMR (300 MHz, CDCl3): d
7.50–7.44 (m, 1H), 7.12–7.09 (m, 2H), 7.01 (d, J 5 9.0 Hz,
1H), 3.97 (t, J 5 7.5 Hz, 2H), 3.32 (s, 2H), 2.67 (s, 6H),
1.65–1.61 (m, 2H), 1.55 (s, 6H), 1.31–1.18 (m, 10H), 0.88
(t, J 5 7.5 Hz, 3H); 13C NMR(75 MHz, CDCl3): d 158.1,
155.7, 144.9, 140.9, 131.0, 129.1, 123.2, 121.3, 114.6,
112.3, 83.7, 76.0, 68.4, 31.6, 29.6, 29.2, 29.1, 28.8, 25.8,
22.6, 14.0, 13.4, 12.6; MS (ESI): m/z calcd for
Synthesis of Reference Compound 6
Compound 6 was synthesized from 3 and 5 by following the
same procedure as preparation of M-2. 1H NMR (300 MHz,
CDCl3): d 7.53–7.50 (m, 16H), 7.11–7.06 (m, 8H), 6.90–6.85
(m, 16H), 6.77 (d, J 5 9.0 Hz, 2H), 6.49 (brs, 2H), 5.97 (s,
2H), 3.87 (t, J 5 6.0 Hz, 4H), 3.74 (t, J 5 6.0 Hz, 4H), 2.92
(s, 8H), 1.78–1.59 (m, 8H), 1.54–1.29 (m, 8H), 1.00 (t, J 5
7.5 Hz, 6H), 0.85 (t, J 5 7.5 Hz, 6H); 31P NMR (162 MHz,
CDCl3): d 48.51; FTIR (KBr, cm21): 2051 (tCCRu); ELEM. ANAL.
calcd (%) for C84H90O4P4Ru: C 72.66, H 6.53; Found: C
72.28, H 6.61; MS (ESI): m/z calcd for C84H90O4P4Ru:
1388.48 [M1]; found: 1388.55.
Synthesis of P-1
A mixture of M-1 (48.6 mg, 0.097 mmol), M-2 (160 mg,
0.097 mmol), Pd(PPh3)4 (5.6 mg, 5% mmol), CuI (1.88 mg,
10% mmol) were added to THF (10 mL) and Et3N (5 mL)
under N2 atmosphere. The reaction was stirred at 40 ꢀC for
40 h. Then the mixture was cooled to room temperature and
filtrated through a short silica gel column. Then the polymer
was precipitated in methanol (100 mL). The polymer was fil-
trated and washed with methanol several times. Further
purification could be conducted by dissolving the polymer in
CH2Cl2 to precipitate in methanol again. The polymer was
dried in vacuum to afford P-1 (140 mg, 76.2%) as a deep
blue solid. GPC results: Mw 5 12,050, Mn 57440, polydisper-
C
31H35BF2N2O: 500.28 [M1]; found: 501.30.
Synthesis of M-2
A mixture of 4 (360 mg, 0.97 mmol) and Et3N (0.3 mL) in
CH2Cl2 (20 mL) was added to 3 (315 mg, 0.33 mmol) and
KPF6 (195 mg, 0.97 mmol) in CH2Cl2 (10 mL). The reaction
was stirred for 40 h at room temperature. After filtration,
the filtrate was concentrated to afford the residue. Then the
residue was washed with hexane, water, and ethanol con-
secutively to afford 315 mg crude product as a deep yellow
solid. The crude product was recrystallized in hexane/
1
sity index (PDI) 5 1.62; H NMR (300 MHz, CDCl3): d 7.47–
7.45 (br, 17H), 7.12 (s, 2H), 7.11–7.07 (m, 10H), 6.93–6.84
(m, 17H), 5.87–5.79 (m, 2H), 3.99–3.84 (m, 6H), 3.68–3.60
(m, 4H), 2.91–2.68 (m, 14H), 1.79–1.17 (m, 34H), 1.02–0.83
(m, 15H); FTIR(KBr, cm21): 2928, 2869, 2192, 2048, 1525,
1485, 1466, 1312, 1189, 1010, 695, 530; ELEM. ANAL. calcd
(%) for C115H123BF2N2O5P4Ru: C 73.20, H 6.57; Found: C
71.62, H 6.03.
1
CH2Cl2 to afford M-2 (280 mg, 52.5%) as a yellow solid. H
NMR (300 MHz, CDCl3): d 7.48–7.46 (m, 16H), 7.23 (s, 2H),
7.12–7.07 (m, 8H), 6.89–6.84 (m, 16H), 5.74 (s, 2H), 3.90
(t, J 5 6.0 Hz, 4H), 3.67 (t, J 5 6.0 Hz, 4H), 2.91 (s, 8H),
1.79–1.30 (m, 16H), 1.00 (t, J 5 7.5 Hz, 6H), 0.86 (t, J 5 7.5
Hz, 6H); 31P NMR (162 MHz, CDCl3): d 44.99; FTIR (KBr,
cm21): 2048 (tCCRu); ELEM. ANAL. calcd (%) for C84H88I2O4-
Synthesis of P-2
A mixture of M-1 (80 mg, 0.160 mmol), M-3 (118.7 mg,
0.160 mmol), Pd(PPh3)4 (9.2 mg, 5% mmol), CuI (3.04 mg,
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SCHEME 1 Synthesis of monomers and polymers.
10% mmol) was dissolved in THF (10 mL) and Et3N (5 mL)
under N2 aꢀtmosphere. The reaction mixture was stirred for
40 h at 40 C. Then the mixture was cooled to room temper-
ature and filtrated through a short silica gel column. Then
the polymer was precipitated in methanol (100 mL). The
polymer was filtrated and washed with methanol several
times. Further purification could be conducted by dissolving
the polymer in CH2Cl2 to precipitate in methanol again. The
polymer was dried in vacuum to afford P-2 (132 mg, 83.2%)
as a deep red solid. GPC results: Mw 515,980, Mn 5 10,380,
[Ru(dppe)2Cl2] (3),34,35 1,4-dibutoxy-2-ethynyl-5-iodobenzene
(4),36 and 1,4-dibutoxy-2-ethynylbenzene (5)37 were pre-
pared according to reported literatures. M-1 was synthesized
by Pd-catalyzed Sonogashira coupling reaction of compound
2 and trimethylsilylacetylene, M-2 and reference compound 6
were synthesized by the dehydrohalogenation reaction from
compound 3 and 4 or 5.38,39 1,4-Bis(2,5-dibutoxy-4-iodophe-
nyl)buta-1,3-diyne (M-3) was prepared by Cu-catalyzed oxi-
dative coupling reaction from the compound 4 in a moderate
yield of 64.3%.40,41 P-1 and P-2 were synthesized by Pd-
catalyzed Sonogashira coupling reaction from M-1 and M-2
or M-3 in yields of 76.2 and 83.2%, respectively. The chemi-
cal structures of the polymers could be confirmed by 1H
NMR and IR spectroscopies. Compared with the 1H NMR
spectra of monomers, the two polymers have the related pro-
ton signals, and no peaks at about 3.3 ppm where acetylene
protons resonate. Meanwhile, the IR spectrum of P-1 and P-2
also show no absorption bands at about 3300 cm21 which
are assignable to the stretching vibrations of BCH. This dem-
onstrates the successful preparation of the target polymers.
The resulting polymers show excellent solubility in common
organic solvents. The number average molecular weight and
PDI of the polymers measured by GPC were Mn 5 7440 and
PDI 5 1.62 for P-1, Mn 5 10,380 and PDI 5 1.54 for P-2.
1
PDI 5 1.54; H NMR (300 MHz, CDCl3): d 7.60–7.54 (m, 1H),
7.18–7.11 (m, 2H), 7.04–7.00 (m, 1H), 6.96 (s, 2H), 6.90(s,
2H), 4.03–3.94 (m, 10H), 2.76–2.69 (m, 6H), 1.84–1.72 (m,
8H), 1.64–1.44 (m, 16H), 1.28–1.19 (m, 10H), 1.03–0.92(m,
12H), 0.88–0.80 (m, 3H); FTIR(KBr, cm21): 2928, 2870,
2200, 2138, 1532, 1491, 1468, 1316, 1184, 1012, 713, 584;
ELEM. ANAL. calcd (%) for C63H75BF2N2O5: C 76.50, H 7.64;
Found: C 74.69, H 6.22.
RESULTS AND DISCUSSION
Synthesis and Structural Characterization
The synthetic routes to the monomers and polymers are
shown in Scheme 1. BODIPY derivatives (1, 2),32,33 cis-
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Figure 1, and the corresponding optical data is listed in
Table 1. As shown in UV–vis absorption spectra [Fig. 1(a)]
measured in solutions, M-1 appears as a strong S0!S1 (p–
p*) transition at 538 nm and a much weaker broad band at
a shorter wavelength 388 nm probably ascribing to S0!S2
(p–p*) transition. Reference compound 6 has an absorption
peak at 353 nm due to metal-to-ligand charge transfer
1
S0! MLCT. P-1 and P-2 appear as two distinct bands in the
absorption spectra. One band at shorter wavelengths is
assigned to their localized p–p* transition, and the other
band at longer wavelengths is attributed to intramolecular
charge transfer (ICT) between Ru(II) bis(acetylide) complex
or aryl diyne moieties as electron-rich donors and BODIPY
moieties as electron-deficient acceptors. Compared with
M-1, the absorption peak of P-2 is red-shifted by 74 nm
probably ascribing to the extended p-conjugation structure.
Compared with P-2, P-1 shows a 22 nm redshift for the
absorption over 600 nm wavelength region. This could
attribute to the introduction of the electron-rich Ru(II) com-
plex moieties. Herein, the absorption spectra of P-1 and P-2
in the solid films appear more broad absorption bands in
the range of 480–800 nm and obvious redshifts as high as
29 nm and 26 nm compared with those in solutions, respec-
tively, which could be attributed to the strong interchain
associations and aggregations. In addition, the optical
bandgaps of P-1 and P-2 could be calculated as 1.52 and
1.73 eV from the thin film UV–vis spectra by using the equa-
tion Eg 5 1240/kedge, demonstrating the tunable bandgaps
upon the introduction of Ru(II) complex moieties in CP. In
the fluorescence spectra [Fig. 1(b)] measured in solutions,
M-1 has an emission peak at 553 nm. The reference com-
pound 6 has an emission peak at 403 nm. P-2 has one emis-
sion peak at 645 nm which is obviously red-shifted relative
to M-1 due to the extended p-conjugation structure. When
the Ru(II) complex moiety is introduced into the CP, P-1
shows 8 nm redshift compared to P-2. We also found that
the fluorescent emission intensities of both P-1 and P-2 in
the solid films were too weak to be detected probably due
to the aggregation-caused quenching (ACQ). In addition, the
fluorescence decay profile of P-1 was obtained with excita-
tion at 580 nm and detection at 630 nm. The weight aver-
age lifetime (s) of P-1 was 1.02 ns (Supporting Information
Fig. S19) which indicated the emission from singlet state.
The small stokes shift of P-1 (19 nm) also indicated the
emission from singlet state.43 The optical data indicates that
FIGURE 1 (a) Normalized UV–vis absorption spectra in CH2Cl2
solutions and solid films and (b) Normalized emission spectra
in CH2Cl2 solutions of 6, M-1, P-1, P-2.
The TGA curves (Supporting Information Fig. S18) reveal that
the degradation temperature (Td) of 5% weight loss of P-1
ꢀ
and P-2 are 269 and 268 C, respectively, which indicates an
excellent thermal stability of the polymers.
Optical Properties
The UV–vis absorption and fluorescence spectra of the
polymers, M-1 and reference compound 6, are shown in
TABLE 1 Optical Data of 6, M-1, P-1, and P-2 (1.0 3 1025 mol L21, CH2Cl2)
abs, sol. (nm)a
kabs, film (nm)b
kabs (nm)a
Eg (eV)c
QF
d
k
6
353
–
403
553
653
645
–
–
M-1
P-1
P-2
388, 538
375, 634
409, 612
–
–
0.64
0.08
0.26
369, 663
418, 638
1.52
1.73
a
d
Concentration of 1025 mol L21 in CH2Cl2.
Drop coated from solutions on quartz substrates.
Quantum yields were determined with ZnPc as fluorescence reference
b
c
in DMF (U 5 0.28).42
Optical band gaps were estimated from the absorption spectra in films
by using the equation Eg 5 1240/kedge
.
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phosphate, and redox potentials were calibrated using a
ferrocene–ferrocenium (Fc–Fc1) redox couple as an external
standard. A platinum wire was used as counter electrode
and Ag/AgCl electrode was used as reference electrode. The
CV curves of P-1 and P-2 are shown in Figure 2, and the
electrochemical data is summarized in Table 2. As shown,
P-1 has one more redox wave with a small E1/2 5 20 mV
(᭝ Ep 5 60 mV) [where E1/2 represent the half-wave
potential which get from (Ep,a 1 Ep,c)/2; and d Ep means
the separation of the peak potentials from (Ep,a 2 Ep,c)]
attributing to Ru(II)/Ru(III) redox process. This showed
that the P-1 could provide electrons easily than P-2 due to
the existence of Ru(II) complex. In their oxidation traces,
the onset potentials of P-1 and P-2 occurred at 20.09 and
10.43 V, respectively, probably arising from the oxidation
of the electron-donor units. And in their reduction traces,
P-1 and P-2 exhibited onset potentials at 20.96 and 21.08
V, which could be assigned to the reduction of the electron-
acceptor BODIPY moiety. The highest occupied molecular
orbital (HOMO) and lowest unoccupied molecular orbital
(LUMO) energy levels of the polymers can be calculated
onset
ox
according to the equations of HOMO 5 2e(E
and LUMO 5 2e(E
1 4.8) (eV)
1 4.8) (eV).44 On the basis of these
onset
red
onset potentials, the HOMO/LUMO energy levels of P-1 and
P-2 were determined to be 24.71/23.84 eV and 25.23/
23.72 eV with the corresponding electrochemical bandgaps
of 0.87 and 1.51 eV, respectively. The bandgap of P-1 is
0.64 eV smaller than that of P-2, which demonstrates that
the bandgaps of the CPs could be effectively decreased by
introducing Ru(II) complexes into the polymer main chain.
Molecular Orbital Calculations
To gain a better insight into the geometric and electronic
structure, we performed theoretical calculation analysis on
the model Molecules 1 and 2 constituting the corresponding
repeat units (Fig. 3). All calculations were performed at the
B3LYP/(6-31G(d)1LanL2DZ) level by using Gaussian 09.30,45
Moreover, all the alkyl chains were replaced by methyl groups
in the calculation for simplicity. Figure 3 displays the LUMO
and HOMO of Model 1 and Model 2. The calculated HOMO,
LUMO, and the energy gaps (Eg) of the two models are listed
in Table 2. As shown, the LUMO of both model compounds
are mainly centered on the central BODIPY core, whereas the
HOMO of Model 1 is mainly centered on Ru(II) complex unit
and the HOMO of Model 2 is spread over the whole of
FIGURE 2 Cyclic voltammograms of P-1 and P-2.
the introduction of Ru(II) complex into the main chain of
the polymer could induce redshifts in both UV–vis absorp-
tion and fluorescence spectra.
Electrochemical Properties
The redox behaviors of the two polymers were measured
by cyclic voltammetry (CV). Throughout, deoxygenated
CH2Cl2 solutions and a scan rate of 50 mV s21 were used.
All measurements were performed in N2-saturated solu-
tions containing 0.1 M tetrabutylammonium hexafluoro-
TABLE 2 Electrochemical Data of Polymers and Calculated HOMO, LUMO Energy Values
From CVa
From Calculation
LUMOd (eV)
Eonset oxb (V)
HOMO (eV)
Eonset redb (V)
LUMO (eV)
Eg (eV)
HOMOd (eV)
c
c,d
Eg (eV)
P-1
P-2
20.09
24.71
25.23
20.96
21.08
23.84
23.72
0.87
1.51
24.24
24.88
22.48
22.36
1.76
2.52
0.43
a
c
The ferrocence couple (Fc/Fc1) was used as the internal reference and
Eg 5 LUMO 2 HOMO.
The data was from calculation of Model 1 and Model 2.
under our experimental conditions, E (Fc1/Fc) 5 0.42 V vs. Ag/AgCl.
d
b
Eox and Ered were determined from the onset potentials of the oxida-
tion and reduction waves.
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FIGURE 3 Structures and molecular orbital diagrams for LUMO and HOMO of designed model compounds 1, and 2 from DFT cal-
culations. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
the conjugated backbone. Apparently, in comparison with
Model 2, Model 1 shows a higher HOMO level owing to the
presence of the electron-rich Ru(II) complex moiety in the
polymer backbone. Because of the strong donor–acceptor
interaction between the Ru(II) complex and BODIPY unit, the
calculated bandgap of Model 1 is 0.76 eV smaller than that of
Model 2. Although the calculated energy levels were higher
than those determined by experiments, the trends in the
bandgaps were in good agreement with the ones obtained by
UV–vis and CV measurements of the polymers.
National Basic Research Program of China (2010CB923303)
and open project of Beijing National Laboratory for Molecu-
lar Sciences.
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CONCLUSIONS
2502.
In summary, we have successfully synthesized a novel poly-
mer P-1 containing Ru(II) bis(acetylide) complex and BODIPY
moieties in the main chain by Pd-catalyzed Sonogashira cou-
pling reaction. The UV–vis absorption and fluorescence spec-
tra indicate that the introduction of Ru(II) complex into the
CP could significantly affect the optical properties of the poly-
mer. Also, the optical, electrical, and calculated data further
demonstrates a significant decreased bandgap of the polymer
due to the introduction of Ru(II) complex. These photophysi-
cal and electrochemical properties indicate that the polymer
might have potential in device-based applications.
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