Article pubs.acs.org/Macromolecules
Efficient Synthesis of Fluorinated Phenanthrene Monomers Using Mallory Reaction and Their Copolymerization Hiroki Fukumoto,* Masatoshi Ando, Tomomi Shiota, Hirokazu Izumiya, and Toshio Kubota* College of Engineering, Department of Biomolecular Functional Engineering, Ibaraki University, 4-12-1, Naka-narusawa, Hitachi 316-8511, Japan S Supporting Information *
ABSTRACT: The Mallory reaction of 1,2-diarylhexafluorocyclopentene (1, aryl = 3-bromophenyl; 2, aryl = 4-bromophenyl) under light irradiation (λ = 365 nm) in the presence of iodide proceeded to give dibromophenanthrene derivatives, 3 and 4. Polycondensation of 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol)ester with the obtained monomers by Suzuki− Miyaura coupling afforded the phenanthrene-type copolymers Poly-3 and Poly-4 in high yields. For comparison, diphenylethene-type copolymers (Poly-1 and Poly-2) were also prepared analogously. UV−vis spectra of Poly-3 and Poly-4 in CHCl3 showed π−π* transition peaks at 380 and 354 nm, respectively, and additional shoulder peaks appeared at a longer wavelength in the film, suggesting the molecular assembly of the polymer molecules. In contrast, the spectra of Poly-1 and Poly2 in solution were essentially unchanged as measured in the film, presumably owing to partial interruption of the π-conjugation system in polymer main chains. The copolymers showed photoluminesence (PL) in both CHCl3 and the film.
■
desired for further development of the chemistry of πconjugated fluoropolymers. Octafluorocyclopentene (OFCP) has gained much attention as excellent building blocks for cyclic organofluorine polymers8−11 because of their commercial availability and ease of handling. In addition, OFCP has high reactivity to various nucleophiles such as organolithium reagents,12 Grignard reagents,13 secondary amines,14 and alkoxides15,16 to give the corresponding disubstituted hexafluorocyclopentenes, many of which are used as targets in photochromic studies when the substituents are aromatic units.17 To the best of our knowledge, irreversible photocyclization of diarylhexafluorocyclopentenes has not been reported. In 1964, Mallory discovered the synthesis of phenanthrene derivatives by light irradiation of stilbenes in the presence of catalytic amounts of iodine (Scheme 1).18−20 This indicates that the Mallory reaction can also be applicable to the above diarylhexafluorocyclopentenes for the construction of the
INTRODUCTION
Fluoropolymers have been attracting much interest because of their unique chemical and physical properties such as heat resistance, transparency, and water resistance.1 Applications of the polymers are actively investigated, and some fluoropolymers have been adopted in various industries. Their unique properties originate from the chemical stability, low polarizability, and low cohesive energy of C−F bonds in fluoropolymers. When fluoropolymers have a π-conjugation system along the polymer main chain, they can be used as n-type organic semiconductors for electronic and optical devices. Recently, some examples of fluorine-containing π-conjugated polymers have been reported;2−6 however, they are still limited owing to the difficulty in directly introducing fluorine or organofluorine groups into their corresponding monomeric aromatic compounds. For example, the preparation of fluorinated polycyclic aromatic hydrocarbons, e.g., perfluoropentacene, requires many reaction steps and hazardous fluorination reagents under hard reaction condition.7 Therefore, preparation of fluorinated πconjugated monomers using convenient fluorine sources is © XXXX American Chemical Society
Received: October 3, 2016 Revised: January 8, 2017
A
DOI: 10.1021/acs.macromol.6b02151 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules Scheme 1. Photocyclization of cis-Stilbene in the Presence of I2 (Mallory Reaction)
phenyl proton peaks in the region of 7.6−7.0 ppm. For the spectrum of 3 (Figure S1), three peaks of phenyl units clearly appear at a lower magnetic field (8.5−7.9 ppm) than those observed in the spectrum of 1, owing to the magnetic deshielding effect of the extended π-conjugated phenanthrene framework. A similar peak shift is also observed in the 1H NMR spectra of 2 and 4 (Figure S2). The formation of phenanthrene with a cyclic fluoroalkyl unit by Mallory reaction of 1 and 2 was also confirmed by 19F NMR spectroscopy. The 19F NMR spectra of 1 and 2 (Figures S3 and S4) show two fluorine peaks at a 1:2 integration ratio approximately at −130 and −110 ppm, which appear to be nearly at the same positions as those of symmetrical 1,2disubstituted hexafluorocyclopentenes.12 After light irradiation of 1 and 2, both peaks shift to a lower magnetic field in the spectra of the corresponding Mallory reaction products (3 and 4). Synthesis of Copolymers. The preparation of the copolymers is outlined in Scheme 3. The palladium-catalyzed polycondensation of 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol)ester with 3 and 4 afforded the phenanthrene-type copolymers Poly-3 and Poly-4 in 82% and 89% yields, respectively. To clarify the nature of the phenanthrenetype copolymers, diphenylethene-type copolymers (Poly-1 and Poly-2) were also synthesized analogously. The structures of all the polymers were determined by 1H and 19F NMR spectroscopy (Figures S5−S8) and elemental analysis. The obtained copolymers showed good solubility in organic solvents such as THF and chloroform. As shown in Table 1, GPC-MALS analysis of the phenanthrene-type copolymers (Poly-3 and Poly-4) showed their number-average molecular weights (Mn) to be 25 400 and 12 300, which corresponded to the degrees of polymerization (DP) of 35 and 17, respectively. All the copolymers showed good thermal stability in Ar atmosphere. For example, the TGA curves of Poly-2 and Poly4 exhibited 5% weight loss at 406 °C. UV−Vis and Photoluminescence Spectra. UV−vis and photoluminescence (PL) spectra of all the copolymers are shown in Figures 1 and 2, respectively, and the optical data are summarized in Table 2. UV−vis spectra of the copolymers were measured at a concentration of 10 −5 M. In CHCl 3 , diphenylethene-type copolymers Poly-1 (Figure 1a) and
phenanthrene skeleton including the cyclic perfluoroalkyl group. The fluorinated phenanthrenes obtained by organometallic polycondensation21 can be monomers for π-conjugated fluoropolymers if aromatic units in the starting nucleophiles (e.g., ArLi and ArMgX) include leaving groups such as halogens. Here, we report a new approach to the synthesis of fluorinated phenanthrene derivatives using the Mallory reaction. We also describe the copolymerization of the monomers by Suzuki−Miyaura coupling22 and the basic chemical properties of the resulting fluoropolymers.
■
RESULTS AND DISCUSSION Synthesis of Monomers. Scheme 2 shows the synthesis routes to 1,2-bis(bromophenyl)-hexafluorocyclopentenes (1 and 2) and the corresponding phenanthrenes (3 and 4). The reaction of octafluorocyclopentene (OFCP) with 3-bromophenyllithium at a 1:2 molar ratio at −78 °C gave 1,2-di(3bromophenyl)hexafluorocyclopentene 1 as a pale yellow oil in 61% yield. Instead of 3-bromophenyllithium, the similar use of 4-bromophenyllithium afforded oily 1,2-di(4-bromophenyl)hexafluorocyclopentene 2 in 54% yield. The Mallory reaction of 1 and 2 in benzene was carried out under light irradiation (λ = 365 nm) in the presence of iodine (0.5 equiv) as an oxidant and excess amounts of 1,2epoxybutane as a scavenger of the hydrogen iodide formed at rt to give the corresponding ring-closed products 3 (15%) and 4 (38%), respectively. In the case of 3, there are two possible regioisomers (3′ and 3″); however, neither was detected. This indicates that the intramolecular ring-closing reaction preferentially proceeded at the C6 position on the phenyl units, presumably owing to prevention of steric repulsion between the bulky bromines or between bromine and hydrogen. The 1H and 19F NMR spectra of 1−4 are in reasonable agreement with their structures, as shown in Figures S1−S4. The 1H NMR spectrum of 1 (Figure S1) in CDCl3 shows four Scheme 2. Routes to Synthesis of Monomersa
Key: (i) 3-bromophenyllithium (2.0 equiv), THF, −78 °C, 1 h, then rt, 3 h; (ii) l2 (0.5 equiv), 1,2-epoxybutane (excess), benzene under light irradiation (λ = 365 nm), rt, 5 h; (iii) 4-bromophenyllithium (2.0 equiv), THF, −78 °C, 1 h, then rt, 3 h; (iv) l2 (0.5 equiv), 1,2-epoxybutane (excess), benzene under light irradiation (λ = 365 nm), rt, 2 h. a
B
DOI: 10.1021/acs.macromol.6b02151 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules Scheme 3. Synthesis of Copolymers
absorption maximum of Poly-1 (λmax = 329 nm) is comparable to those of the starting monomers owing to the partial interruption of the π-conjugation system by m-linked phenylene units.23,24 In the film cast on a quartz plate, the spectra of poly-1 and poly-2 are almost the same as those observed in CHCl3 solution, presumably because the diphenylethene-type copolymers are flexible, which prevents the self-assembly of the polymer molecules in the solid state. The spectrum of the phenanthrene-type copolymer Poly-3 (Figure 1c) in CHCl3 shows a π−π* transition peak at 380 nm, which locates at a considerably longer wavelength than that of the corresponding diphenylethene-type Poly-1 (λmax = 329 nm) as described above, because of the expansion of π-conjugation along the linear polymer chain. Homopolymer analogues of Poly-3, poly(4,5-didecylphenanthylene-2,7-diyl)25−28 and poly(9,9-dioctylfluorene-2,7-diyl),29 show π−π* transition peaks at 390 and 391 nm, respectively. This indicates that the electronic state along the polymer main chain of Poly-3 is basically similar
Table 1. Preparation of Copolymers polymer
Mna
Mwa
yield (%)
Poly-1 Poly-2 Poly-3 Poly-4
6890b 15800b 25400c 12300c
18200b 36400b 42000c 18100c
93 63 82 89
Tdd
(°C)
400 406 381 406
a Estimated by GPC-MALS measurement. bCHCl3 eluent. cTHF eluent. d5% weigth-loss temperature measured by TGA under Ar at a heating rate of 10 °C.
Poly-2 (Figure 1b) show π−π* transition peaks (λmax) at 329 and 350 nm, respectively. The λmax peak position of Poly-2 (λmax = 350 nm) shifts to a longer wavelength than those of monomeric compounds (e.g., λmax = 318 nm for 9,9dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol)ester and λmax = 294 nm for 2), indicating the extension of the πconjugation system along the polymer chain. In contrast, the
Figure 1. UV−vis spectra of (a) Poly-1 (4 × 10−5 M), (b) Poly-2 (3 × 10−5 M), (c) Poly-3 (5 × 10−5 M), and (d) Poly-4 (3 × 10−5 M) in CHCl3 (solid line) and in film cast on a quartz plate (dashed line). C
DOI: 10.1021/acs.macromol.6b02151 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
Figure 2. Photoluminescence spectra of (a) Poly-1 (3.1 × 10−6 M), (b) Poly-2 (3.1 × 10−6 M), (c) Poly-3 (1.5 × 10−6 M), and (d) Poly-4 (1.4 × 10−6 M) in CHCl3 (solid line) and film cast on a quartz plate (dashed line).
Poly-3 (4.5 × 10−5 M), the intensity of absorption maximum at 380 nm decreases and a new peak appears around 410 nm, indicating formation of colloidal aggregates. For Poly-4, a similar phenomenon is observed. These phenomena also support aggregation of Poly-3 and Poly-4 in solid. In this case, planar phenanthrene units in Poly-3 and Poly-4 are thought to assist in molecular assembly, although the polymers contain bulky perfluorocyclopropane and dioctylfluorene frameworks. The copolymers are photoluminescent in both solution and the film (Figure 2). PL spectra of the copolymers were measured at a concentration of 10−6 M. In CHCl3, the PL peaks (λem) of phenanthrene-types Poly-3 (Figure 2c) and Poly-4 (Figure 2d) appear near the onset position of the UV−vis absorption bands, as usually obtained with π-conjugated polymers. The PL quantum yields (Φ in Table 2) of Poly-3 and Poly-4 in CHCl3 were 0.37 and 0.60, respectively. In the film, the PL peaks shift to a long wavelength. In particular, the spectrum of Poly-3 exhibits a peak broadening at approximately 520 nm with a large red-shift (ca. 100 nm). Such a Storks shift is often observed with phenanthrene derivatives.34,35 Actually, all the prepared copolymers in both solution and the film show a Storks shift (Table 2). In the case of Poly-3 film, the large Storks shift and the broadening emission peak seem to be due to aggregation of the linear π-conjugated Poly-3 molecules.25 However, there are no experimental evidence for explanation of the phenomena, which should be further studied. The diphenylethene-type Poly-1 (Φ = 0.03) exhibited a very weak PL peak at approximately 480 nm in CHCl3 (Figure 2a). The very low Φ value of Poly-1 was due to the small effective π-conjugation length obtained by introducing nonconjugated m-phenylene units into the polymer main chain. In the film, the PL peak shifted by 30 nm to a short wavelength. In contrast, a strong peak was observed at 486 nm in the PL spectrum of π-
Table 2. UV−Vis and Photoluminescence Spectral Data of Copolymers λmax (nm) polymer Poly-1 Poly-2 Poly-3 Poly-4
in CHCl3a (ε × 104) 329 350 380 354
(3.9) (3.7) (1.8) (3.3)
λem (nm) film 329 350 380, 410d 354, 400d
in CHCl3b (Φc) 478 486 416 426
(0.03) (0.72) (0.37) (0.60)
film 448 498 520 463
Concentration: 4 × 10−5 M (Poly-1), 3 × 10−5 M (Poly-2), 5 × 10−5 M (Poly-3), and 3 × 10−5 M (Poly-4). bConcentration: 3.1 × 10−6 M (Poly-1), 3.1 × 10−6 M (Poly-2), 1.5 × 10−6 M (Poly-3), and 1.4 × 10−6 M (Poly-4). cPL quantum yield calculated by comparing with the standard of quinine sulfate (ca. 105 M solution in 0.5 M H2SO4, having a quantum yield of 54.6%). dShoulder peak. a
to those of the above analogues. On the other hand, Poly-4 (λmax = 354 nm) (Figure 1d) and its diphenylethene-type Poly2 (λmax = 350 nm) in solution show the π−π* transition peak at almost the same position. This suggests that the contribution of the 3,6-linked phenanthrene units to the π-conjugation system of Poly-4 seems to be not large. Similar UV−vis spectral differences due to the linkage of monomeric units are also observed in six-membered poly(arylene)s, e.g., poly(phenylene)s,23 poly(pyridine)s,24 and poly(phenanthrene)s.25−28 In the film, the additional shoulder peaks appeared at approximately 410 nm for Poly-3 and 400 nm for Poly-4, which were assignable to the aggregation of the polymer molecules. π-Conjugated polymers, which take a highly ordered structure in the film, often show similar shoulder peak(s) or longer wavelength shifts in their UV−vis spectra.30−33 Addition of a poor solvent (e.g., methanol) to a solution of π-conjugated polymer sometimes caused π-stacked molecular assembly.32 When MeOH was added to a homogeneous CHCl3 solution of D
DOI: 10.1021/acs.macromol.6b02151 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
phenanthrene-type (Poly-3 and Poly-4) and diphenylethenetype (Poly-1 and Poly-2) copolymers with high Td at 5% weight loss ranging from 380 to 410 °C. The phenanthrenetype Poly-3 and Poly-4 extended their π-conjugation from the monomeric units in solution, as revealed by UV−vis spectroscopy. Linear Poly-3 molecules showed a tendency to selfassemble to take a highly ordered structure in the film. The copolymers showed photoluminescent properties in CHCl3 and the film. This finding will contribute to the design of new fluorinated polycyclic aromatic compounds and their πconjugated polymers with electronic and optical properties.
conjugated Poly-2 (Φ = 0.71) in CHCl3 (Figure 2b), which shifted to about 500 nm in the film. XRD Patterns and Structures. Figure 3 shows XRD patterns measured with cast films of the copolymers. About 20
■
EXPERIMENTAL SECTION
General Procedure. All manipulations were carried out in an argon atmosphere. 1H and 19F NMR spectra were recorded on a Bruker AVANCE III 400 spectrometer. UV−vis and photoluminescence spectra were measured with a Shimadzu UV-3100PC spectrometer and a Hitachi F-4500 spectrometer, respectively. Elemental analysis was carried out using a J-Science Lab JM10 microanalyzer. Gel permeation chromatography (GPC) of the obtained polymers was performed at TOSOH Analysis and Research Center Co., Ltd., using a TOSOH HLC-8120GPC liquid chromatograph. CHCl3 (for Poly-1 and Poly-2) and THF (for Poly-3 and Poly4) were eluted, and polystyrene was used as the standards. The GPCMALS (MALS = multiangle laser light scattering) technique was carried out at Toray Research Center, Inc., using a Agilent MODEL 1100 pump, TOSOH TSKgel columns (two GMHHR-N columns for Poly-1 and Poly-2, eluent = CHCl3; two GMHXL columns for Poly-3 and Poly-4, eluent = THF), a Wyatt Technology Optilab T-rEX differential refractometer, and Wyatt Technology DAWN HELEOS-II MALS detector. Concentration of the copolymers through the GPC columns is about 1 mg/2 mL (ca. 7 × 10−4 M). X-ray diffraction (XRD) patterns of polymer films were obtained by using a Rigaku SmartLab-SP/IUA X-ray diffractometer with Cu Kα (1.54 Å) radiation. Thermogravimetric analysis (TGA) was carried out using a Rigaku Therm Plus EVO. The Mallory reaction of 1 and 2 was carried out using USHIO Optical Modulex Multipurpose lighting unit (irradiation wavelength = 365 nm, light power = 20 mW/cm2). Octafluorocyclopentene (OFCP), 1-bromo-3-iodobenzene, p-dibromobenzene, 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3propanediol)ester, and Pd(PPh3)4 were purchased and used without further purification. Synthesis of 1. To a THF solution of 1-bromo-3-iodobenzene (1.13 g, 4.0 mmol) was added nBuLi (2.5 mL of 1.60 M hexane solution, 4.0 mmol) at −78 °C, and the reaction mixture was stirred for 20 min. Octrafluorocyclopentene (OFCP) (0.42 g, 2.0 mmol) was dropped to the reaction mixture at −78 °C. The reaction temperature was kept at −78 °C for 1 h and then raised up to rt for 3 h. The reaction mixture was poured into water (10 mL) and extracted with ether (30 mL). The organic layer was dried over Na2SO4, and the solvent was removed at a reduced pressure. The crude product was purified by column chromatography on silica (eluent = hexane) to give 1 as a pale yellow oil (0.59 g, 61%). 1H NMR (400 MHz, CDCl3): δ 7.60 (m, 2H), 7.55 (brs, 2H), 7.26−7.25 (m, 4H). 19F NMR (376 MHz, CDCl3): δ −131.6 (m, 2F), −110.5 (t, J = 4.8 Hz, 4F). Anal. Calcd for C17H8Br2F6: C, 42.01; H, 1.66. Found: C, 42.52; H, 1.86. Compound 2 was prepared analogously. Compound 2. Pale yellow oil; 54% yield. 1H NMR (400 MHz, CDCl3): δ 7.53 (m, 4H), 7.22 (m, 4H). 19F NMR (376 MHz, CDCl3): δ −131.6 (m, 2F), −110.5 (t, J = 4.8 Hz, 4F). Anal. Calcd for C17H8Br2F6: C, 42.01; H, 1.66. Found: C, 42.77; H, 1.82. Synthesis of 3. A mixture of 1 (0.97 g, 2.0 mmol), iodine (0.25 g, 1.0 mmol), and benzene (180 mL) was stirred at rt for 30 min in Ar atmosphere. 1,2-Epoxybutane (6.0 mL, 70 mmol) was added to the mixture, and the mixture was stirred under light irradiation45 from a lighting unit (irradiation wavelength = 365 nm, light power = 20 mW/ cm2) at rt for 5 h. The reaction mixture was washed with saturated sodium thiosulfate aqueous solution (50 mL), distilled water (50 mL),
Figure 3. XRD patterns of cast films of (a) Poly-1, (b) Poly-2, (c) Poly-3, and (d) Poly-4 on a silicon-low background sample holder. Concentrations of polymer solutions for cast on a holder are 5 × 10−2 M for Poly-1 and Poly-2 (in CHCl3) and 2 × 10−2 M for Poly-3 and Poly-4 (in THF).
μL of a polymer solution (5 × 10−2 M for Poly-1 and Poly-2 in CHCl3 and 2 × 10−2 M for Poly-3 and Poly-4 in THF) was cast on a silicon-low background sample holder. In both cases of Poly-1 (Figure 3a) and Poly-2 (Figure 3b), a broad peak at 2θ = 18.5° is considered to correspond to a side-to-side distance (ca. 4.8 Å) between loosely packed alkyl side chains on fluorene units, as often observed with other π-conjugated polymers with such long side chains.36,37 On the other hand, a peak at about 2θ = 21°−24° (ca. 3.7−4.0 Å) originated from a distance of face-to-face packing does not clearly appear in the XRD patterns.38−43 This indicates that long alkyl chains extended from sp3 carbon in the fluorene units may prevent the face-to-face packing of the polymer main chains. The flexible polymer molecules of Poly-1 and Poly-2 basically have weak interaction based on loosely packed alkyl side chains in film, which is consistent with the UV−vis spectral data as described above. For Poly-3 (Figure 3c) and Poly-4 (Figure 3d), a peak appeared at about 2θ = 19.5° (ca. 4.6 Å) is somewhat sharper than that observed with Poly-1 and Poly-2. This result and appearance of a shoulder UV peak around 400 nm (Figures 1c and 1d) support self-assemble of rigid Poly-3 and Poly-4 molecules. Recent WAXS (wide-angle X-ray scattering) studies on structure of arylene-containing polyfluorene in film have revealed that aromatic units in polymer main chains are stacked with a distance of 4.5 Å.44 Thus, the phenanthrene or fluorene units in Poly-3 and Poly-4 may partly aggregate each other to form an ordered structure in film. Further investigation to reveal intermolecular interaction between fluorine-containing phenanthrenes and their detail packing structures is under progress.
■
CONCLUSION New fluorinated phenanthrene derivatives (3 and 4) for monomers of fluorine-containing π-conjugated polymers were obtained by Mallory reaction of the 1,2-diphenylethene precursors (1 and 2) under light irradiation. The obtained phenanthrene and diphenylethene compounds were polymerized with 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3propanediol)ester using Suzuki−Miyaura coupling to give E
DOI: 10.1021/acs.macromol.6b02151 Macromolecules XXXX, XXX, XXX−XXX
Macromolecules
■
and brine (50 mL) in this order. After separation and drying of the benzene layer, the solvent was removed at a reduced pressure. The residue was purified by recrystallization using hexane to afford 3 as colorless crystals (0.14 g, 15%). 1H NMR (400 MHz, CDCl3): δ 8.49 (d, J = 9.0 Hz, 2H), 8.42 (d, J = 2.0 Hz, 2H), 7.91 (dd, J = 9.0 and 2.0 Hz, 2H). 19F NMR (376 MHz, CDCl3): δ −128.9 (m, 2F), −105.8 (t, J = 4.1 Hz, 4F). Anal. Calcd for C17H6Br2F6: C, 42.18; H, 1.25. Found: C, 42.75; H, 1.32. 4 was synthesized similarly to 3. Compound 4. Colorless solid; 38% yield. 1H NMR (400 MHz, CDCl3): δ 8.71 (d, J = 1.8 Hz, 2H), 8.15 (d, J = 8.6 Hz, 2H), 7.83 (dd, J = 8.6 and 1.8 Hz, 2H). 19F NMR (376 MHz, CDCl3): δ −128.8 (m, 2F), −105.6 (t, J = 4.0 Hz, 4F). Anal. Calcd for C17H6Br2F6: C, 42.18; H, 1.25. Found: C, 42.38; H, 1.41. Typical Procedure of Synthesis of Copolymers. A mixture of 1 (0.087 g, 0.18 mmol), 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3propanediol)ester (0.10 g, 0.18 mmol), distilled water (12 mL), K2CO3 (0.10 g), Pd(PPh3)4 (10 mg, 0.0086 mmol, 5 mol %), and THF (12 mL) was stirred at 60 °C for 24 h. The reaction mixture was cooled to rt, and the organic layer was poured into methanol (ca. 200 mL) to precipitate a pale green solid, which was collected by filtration. The pale green filtrate was washed with methanol repeatedly and dried at a reduced pressure to yield a pale gray solid of Poly-1 (0.12 g, 93% yield). 1H NMR (400 MHz, CDCl3): δ 7.74−6.96 (14H), 1.90−1.63 (4H), 1.13−0.58 (26H), 0.55−0.26 (4H). 19F NMR (376 MHz, CDCl3): δ −131.5 (2F), −110.2 (4F). Anal. Calcd for (C46H48F6)n: C, 77.29; H, 6.77. Found: C, 76.39; H, 6.66. GPC (eluent = CHCl3, vs polystyrene standards): Mn = 2900; Mw = 14 000. GPC-MALS (eluent = CHCl3): Mn = 6890; Mw = 18 200. Poly-2, Poly-3, and Poly-4 were prepared analogously. Poly-2. 63% yield. 1H NMR (400 MHz, CDCl3): δ 7.69 (2H), 7.65−7.56 (4H), 7.52 (2H), 7.49 (2H), 7.44 (4H), 2.06 (4H), 1.14 (20H), 0.68 (6H), 0.58 (4H). 19F NMR (376 MHz, CDCl3): δ −131.5 (2F), −110.1 (4F). Anal. Calcd for (C46H48F6)n: C, 77.29; H, 6.77. Found: C, 76.53; H, 6.77. GPC (eluent = CHCl3, vs polystyrene standards): Mn = 4900; Mw = 24 000. GPC-MALS (eluent = CHCl3): Mn = 15 800; Mw = 36 400. Poly-3. 82% yield. 1H NMR (400 MHz, CDCl3): δ 8.93−7.25 (12H), 2.25−1.83 (4H), 1.17−0.99 (20H), 0.86−0.62 (10H). 19F NMR (376 MHz, CDCl3): δ −128.9 (2F), −105.4 (4F). Anal. Calcd for (C46H46F6)nH2O: C, 75.59; H, 6.62. Found: C, 75.43; H, 7.05. GPC (eluent = THF, vs polystyrene standards): Mn = 12 000; Mw = 42 000. GPC-MALS (eluent = THF): Mn = 25 400; Mw = 42 000. Poly-4. 89% yield. 1H NMR (400 MHz, CDCl3): δ 9.21−7.59 (12H), 2.15 (4H), 1.03 (20H), 0.85−0.55 (10H). 19F NMR (376 MHz, CDCl3): δ −128.6 (2F), −105.4 to −106.5 (4F). Anal. Calcd for (C46H46F6)nH2O: C, 75.59; H, 6.62. Found: C, 76.15; H, 6.41. GPC (eluent = THF, vs polystyrene standards): Mn = 8000; Mw = 14 000. GPC-MALS (eluent = THF): Mn = 12 300; Mw = 18 100.
■
ACKNOWLEDGMENTS This work was partially supported by JSPS KAKENHI (15K05513). The authors thank the Center for Instrumental Analysis, Ibaraki University, for elemental analysis.
■
REFERENCES
(1) Smith, D. W., Jr.; Iacono, S. T.; Iyer, S. S. Handbook of Fluoropolymer Science and Technology; Wiley: Hoboken, NJ, 2014. (2) Zhong, W.; Xiao, J.; Sun, S.; Jiang, X.-F.; Lan, L.; Ying, L.; Yang, W.; Yip, H.-L.; Huang, F.; Cao, Y. Wide Bandgap Dithienobenzodithiophene-based π-Conjugated Polymers Consisting of Fluorinated Benzotriazole and Benzothiadiazole for Polymer Solar Cells. J. Mater. Chem. C 2016, 4, 4719−4727. (3) Gedefaw, D.; Tessarolo, M.; Zhuang, W.; Kroon, R.; Wang, E.; Bolognesi, M.; Seri, M.; Muccini, M.; Andersson, M. R. Conjugated Polymers Based on Benzodithiophene and Fluorinated Quinoxaline for Bulk Heterojunction Solar Cells: Thiophene versus Thieno[3,2b]thiophene as π-Conjugated Spacers. Polym. Chem. 2014, 5, 2083− 2093. (4) Lu, W.; Kuwabara, J.; Iijima, T.; Higashimura, H.; Hayashi, H.; Kanbara, T. Synthesis of π-Conjugated Polymers Containing Fluorinated Arylene Units via Direct Arylation: Efficient Synthetic Method of Materials for OLEDs. Macromolecules 2012, 45, 4128− 4133. (5) Takeda, Y.; Andrew, T. L.; Lobez, J. M.; Mork, A. J.; Swager, T. M. An Air-Stable Low-Bandgap n-Type Organic Polymer Semiconductor Exhibiting Selective Solubility in Perfluorinated Solvents. Angew. Chem., Int. Ed. 2012, 51, 9042−9046. (6) Chen, H.-C.; Chen, Y.-H.; Liu, C.-H.; Hsu, Y.-H.; Chien, Y.-C.; Chuang, W.-T.; Cheng, C.-Y.; Liu, C.-L.; Chou, S.-W.; Tung, S.-H.; Chou, P.-T. Fluorinated Thienyl-quinoxaline-based D−π−A-type Copolymer toward Efficient Polymer Solar Cells: Synthesis, Characterization, and Photovoltaic Properties. Polym. Chem. 2013, 4, 3411− 3418. (7) Sakamoto, Y.; Suzuki, T.; Kobayashi, M.; Gao, Y.; Fukai, Y.; Inoue, Y.; Sato, F.; Tokito, S. Perfluoropentacene: High-Performance p−n Junctions and Complementary Circuits with Pentacene. J. Am. Chem. Soc. 2004, 126, 8138−8140. (8) Cracowski, J.-M.; Sharma, B.; Brown, D. K.; Christensen, K.; Lund, B. R.; Smith, D. W., Jr. Perfluorocyclopentenyl (PFCP) Aryl Ether Polymers via Polycondensation of Octafluorocyclopentene with Bisphenols. Macromolecules 2012, 45, 766−771. (9) Kubota, T.; Takaki, A. (Ibaraki Univesity). Jpn. Kokai Tokkyo Koho JPN 2006142290, 2006. (10) Briscoe, M. W.; Chambers, R. D.; Silvester, M. J.; Drakesmith, F. G. Electropolymerisation of Perfluorocyclo-alkenes. Tetrahedron Lett. 1988, 29, 1295−1298. (11) Wu, J.; Xi, Y.; McCandless, G. T.; Xie, Y.; Menon, R.; Patel, Y.; Yang, D. J.; Iacono, S. T.; Novak, B. M. Synthesis and Characterization of Partially Fluorinated Polybenzoxazine Resins Utilizing Octafluorocyclopentene as a Versatile Building Block. Macromolecules 2015, 48, 6087−6095. (12) Yamada, S.; Konno, T.; Ishihara, T.; Yamanaka, H. Reaction of Octafluorocyclopentene with Various Carbon Nucleophiles. J. Fluorine Chem. 2005, 126, 125−133. (13) Park, J. D.; Sullivan, R.; McMurtry, R. J. Substitution and Rearrangement Reactions Resulting from the Reaction of Grignard Reagents with Some Alicyclic Polyfluorinated Olefins the Effect of Ring Size on Product Distribution. Tetrahedron Lett. 1967, 8, 173− 176. (14) Barnes, R. N.; Chambers, R. D.; Hewitt, C. D.; Silvester, M. J.; Klauke, E. Reactions Involving Fluoride Ion. Part 31. Co-oligomers of Perfluoro-1-methyl-1,3-diazacyclopent-2- and −3-ene. J. Chem. Soc., Perkin Trans. 1 1985, 53−56. (15) Stockel, R. F.; Beachem, M. T.; Megson, F. H. The Reaction of Methoxide Ion with Perfluorocyclopentene. Can. J. Chem. 1964, 42, 2880−2883.
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.macromol.6b02151. 1 H and 19F NMR spectra of monomers and copolymers (PDF)
■
Article
AUTHOR INFORMATION
Corresponding Authors
*E-mail:
[email protected] (H.F.). *E-mail:
[email protected] (T.K.). ORCID
Hiroki Fukumoto: 0000-0002-7066-3411 Notes
The authors declare no competing financial interest. F
DOI: 10.1021/acs.macromol.6b02151 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
Homopolymers Having Long Side Chains. J. Polym. Sci., Part A-1: Polym. Chem. 1971, 9, 1835−1852. (37) Hsieh, H. W.; Post, B.; Morawetz, H. A Crystallographic Study of Polymers Exhibiting Side-chain Crystallization. J. Polym. Sci., Polym. Phys. Ed. 1976, 14, 1241−1255. (38) Fukumoto, H.; Fujiwara, Y.; Yamamoto, T. Preparation of Head-to-tail π-Conjugated Poly(thiophene-pyridine) and Poly(pyrimidine) by Organometallic Polycondensation. Chem. Lett. 2011, 40, 992−994. (39) Yamamoto, T.; Usui, M.; Ootsuka, H.; Iijima, T.; Fukumoto, H.; Sakai, Y.; Aramaki, S.; Yamamoto, H. M.; Yagi, T.; Tajima, H.; Okada, T.; Fukuda, T.; Emoto, A.; Ushijima, H.; Hasegawa, M.; Ohtsu, H. πConjugated Polymers Consisting of Isothianaphthene and Dialkoxy-pphenylene Units: Synthesis, Self-Assembly, and Chemical and Physical Properties. Macromol. Chem. Phys. 2010, 211, 2138−2147. (40) Yamamoto, T.; Sato, T.; Iijima, T.; Abe, M.; Fukumoto, H.; Koizumi, T.; Usui, M.; Nakamura, Y.; Yagi, T.; Tajima, H.; Okada, T.; Sasaki, S.; Kishida, H.; Nakamura, A.; Fukuda, T.; Emoto, A.; Ushijima, H.; Kurosaki, C.; Hirota, H. Highly Coplanar Polythiophenes with −CCR Side Chains: Self-assembly, Linear and Nonlinear Optical Properties, and Piezochromism. Bull. Chem. Soc. Jpn. 2009, 82, 896− 909. (41) Otsuka, S.-i.; Fukumoto, H.; Yamamoto, T. Electrochemical and Chemical Doping Behavior of Bithiophene-bithiazole Copolymer. Bull. Chem. Soc. Jpn. 2008, 81, 536−538. (42) Fukumoto, H.; Yamamoto, T. Preparation and Chemical Properties of Soluble π-Conjugated Poly(aryleneethynylene) Consisting of Azabenzothiadiazole as the Electron-Accepting Unit. J. Polym. Sci., Part A: Polym. Chem. 2008, 46, 2975−2982. (43) Yamamoto, T. Synthesis of π-Conjugated Polymers Bearing Electronic and Optical Functionalities by Organometallic Polycondensations. Chemical Properties and Applications of the π-Conjugated Polymers. Synlett 2003, 4, 425−450. (44) Faria, G. C.; Plivelic, T. S.; Cossiello, R. F.; Souza, A. A.; Atvars, T. D. Z.; Torriani, I. L.; deAzevedo, E. R. A Multitechnique Study of Structure and Dynamics of Polyfluorene Cast Films and the Influence on Their Photoluminescence. J. Phys. Chem. B 2009, 113, 11403− 11413. (45) Liu, L.; Yang, B.; Katz, T. J.; Poindexter, M. K. Improved Methodology for Photocyclization Reactions. J. Org. Chem. 1991, 56, 3769−3775.
(16) Card, P. J.; Smart, B. E. Reactions of Perfluorocycloalkenones with Nucleophiles. J. Org. Chem. 1980, 45, 4429−4432. (17) Irie, M. Diarylethenes for Memories and Switches. Chem. Rev. 2000, 100, 1685−1716. (18) Mallory, F. B.; Wood, C. S. Photochemistry of Stilbenes. IV. The Preparation of Substituted Phenanthrenes. J. Org. Chem. 1964, 29, 3373−3377. (19) Mallory, F. B.; Wood, C. S.; Gordon, J. T. Photochemistry of Stilbenes. III. Some Aspects of the Mechanism of Photocyclization to Phenanthrenes. J. Am. Chem. Soc. 1964, 86, 3094−3102. (20) Jørgensen, K. B. Photochemical Oxidative Cyclisation of Stilbenes and Stilbenoids−The Mallory-Reaction. Molecules 2010, 15, 4334−4358. (21) Yamamoto, T. Synthesis of π-Conjugated Polymers by Organometallic Polycondensation. Bull. Chem. Soc. Jpn. 2010, 83, 431−455. (22) Suzuki, A.; Miyaura, N. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chem. Rev. 1995, 95, 2457− 2483. (23) Muramatsu, Y.; Yamamoto, T.; Hayakawa, T.; Koinuma, H. Combinatorial Synthesis and Screening for Blue Luminescent πConjugated Polymer Thin Film. Appl. Surf. Sci. 2002, 189, 319−326. (24) Wu, B.; Yamamoto, T. Polycondensation between pDibromobenzene and m-Dibromobenzene. J. Appl. Polym. Sci. 2003, 89, 2210−2215. (25) Yang, C.; Scheiber, H.; List, E. J. W.; Jacob, J.; Müllen, K. Poly(2,7-phenanthrylene)s and Poly(3,6-phenanthrylene)s as Polyphenylene and Poly(phenylenevinylene) Analogues. Macromolecules 2006, 39, 5213−5221. (26) He, B.; Tian, H.; Geng, Y.; Wang, F.; Müllen, K. Facile Synthesis of 9,10-Diarylphenanthrenes and Poly(9,10-diarylphenanthrene)s. Org. Lett. 2008, 10, 773−776. (27) Grisorio, R.; Suranna, G. P.; Mastrorilli, P.; Nobile, C. F. A Versatile Synthesis for New 9,10-Bis(4-alkoxyphenyl)-2,7-diiodophenanthrenes: Useful Precursors for Conjugated Polymers. Org. Lett. 2007, 9, 3149−3152. (28) Vanormelingen, W.; Smeets, A.; Franz, E.; Asselberghs, I.; Clays, K.; Verbiest, T.; Koeckelberghs, G. Conformational Steering in Substituted Poly(3,6-phenanthrene)s: A Linear and Nonlinear Optical Study. Macromolecules 2009, 42, 4282−4287. (29) Huang, L.; Huang, X.; Sun, G.; Gu, C.; Lu, D.; Ma, Y. Study of β phase and Chains Aggregation Degrees in Poly(9,9-dioctylfluorene) (PFO) Solution. J. Phys. Chem. C 2012, 116, 7993−7999. (30) McCullough, R. D.; Tristram-Nagle, S.; Williams, S. P.; Lowe, R. D.; Jayaraman, M. Self-orienting Head-to-tail Poly(3-alkylthiophenes): New Insights on Structure-property Relationships in Conducting Polymers. J. Am. Chem. Soc. 1993, 115, 4910−4911. (31) Chen, T. A.; Wu, X.; Rieke, R. D. Regiocontrolled Synthesis of Poly(3-alkylthiophenes) Mediated by Rieke Zinc: Their Characterization and Solid-State Properties. J. Am. Chem. Soc. 1995, 117, 233− 244. (32) Yamamoto, T.; Komarudin, D.; Arai, M.; Lee, B.-L.; Suganuma, H.; Asakawa, N.; Inoue, Y.; Kubota, K.; Sasaki, S.; Fukuda, T.; Matsuda, H. Extensive Studies on π-Stacking of Poly(3-alkylthiophene2,5-diyl)s and Poly(4-alkylthiazole-2,5-diyl)s by Optical Spectroscopy, NMR Analysis, Light Scattering Analysis, and X-ray Crystallography. J. Am. Chem. Soc. 1998, 120, 2047−2058. (33) Kokubo, H.; Sato, T.; Yamamoto, T. Synthesis of New Thiophene-Based π-Conjugated Polymers for Investigation of Molecular Alignment on the Surface of Platinum Plate. Macromolecules 2006, 39, 3959−3963. (34) Boden, B. N.; Jardine, J. K.; Leung, A. C. W.; MacLachlan, M. J. Tetraalkoxyphenanthrene: A New Precursor for Luminescent Conjugated Polymers. Org. Lett. 2006, 8, 1855−1858. (35) Zimmermann, T. J.; Müller, T. J. J. The First Synthesis and Electronic Properties of Tetrakis[(hetero)phenanthrenyl]methanes. Eur. J. Org. Chem. 2002, 2002, 2269−2279. (36) Jordan, E. F.; Feldeisen, D. W., Jr.; Wrigley, A. N. Side-chain Crystallinity. I. Heats of Fusion and Melting Transitions on Selected G
DOI: 10.1021/acs.macromol.6b02151 Macromolecules XXXX, XXX, XXX−XXX
