Conjugated Polymer Energy Level Shifts in Lithium-Ion Battery ...
Conjugated Polymer Energy Level Shifts in Lithium-Ion Battery Electrolytes Charles Kiseok Song,†,║ Brian J. Eckstein,†,║ Teck Lip Dexter Tam,† Lynn Trahey,*,‡ and Tobin J. Marks*,†,§ †
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States ‡ Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States § Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Cook Hall Room 2036, Evanston, Illinois 60208, United States *Correspondence and requests for materials should be addressed to L.T. ([email protected]) and T.J.M. ([email protected]). ║ These authors contributed equally to this work.
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EXPERIMENTAL Synthesis of the polymers P(3MEMT), P(3POET), P(NDI-tegme2T), and DT003CF are described below. P3HT (RMI-001EE, Mw: 36-90 K, PDI: 2.0 – 2.3, RR: > 96%) was purchased from Rieke Metals, PTB7 and PCDTBT were purchased from 1-Material, and N2200 (Mn = 29.3 K, Mw: 101.7 K, PDI: 3.5) was a gift from Polyera Corp. These polymers were used as received without further purifications. Polymer film preparation. The conjugated polymers, P3HT, P(3POET), P(3MEMT), PTB7, PCDTBT, DT003CF, N2200, and P(NDI-tegme2T), were spin-coated onto Cu foil under ambient condition and onto glass/Cu substrates under Ar atmosphere. Glass substrates (1.0 cm × 2.5 cm) were sequentially cleaned in detergent, deionized water, isopropanol, and acetone for 30 min each at 50°C. Freshly cut Cu foils (1” × 1” in), and glass substrates were subsequently cleaned in a UVO cleaner (20 min). The foils were transferred to a glove box until further use and the substrates were transferred to a metal evaporator. A shadow mask with a circular electrode (0.50 cm2) as in Figure S1 was used to pattern the glass/Cu substrates with a Cu layer of ~120 nm in thickness by thermal evaporation (0.8 Å/s at 2 × 10−7 Torr). Solutions of conducting polymers were prepared in anhydrous chloroform at a concentration of 10 mg/mL under an Ar atmosphere in a glove box and were stirred overnight at 70°C to ensure complete dissolution. The polymer solutions were then applied to the Cu foils and to the patterned glass/Cu substrates by spin-coating at 1200 rpm (~100 nm) for 60 s in a dry box (relative humidity < 5%) and in a N2 filled glove box, respectively. The films on Cu foils were subsequently transferred to the glove box. Optical profilometry. The thickness of the polymer films coated on the glass/Cu substrates were estimated with a Bruker ContourGT Optical Profiler. P3HT solutions (10 mg/mL in
S2
chloroform) were spin-coated on clean glass substrates (1.0 cm × 2.5 cm) at 1200 rpm for 60 s. The center of the coated film was cleaned with an acetone-soaked Q-tip so that the bare glass substrate could be used as a baseline reference. The patterned P3HT-coated substrates were placed in the optical profilometer and the film thickness measured at 0.5× zoom. The largest difference between the clean glass surface and the thickest part of the polymer film was then calculated. Ultraviolet Photoelectron Spectroscopy (UPS) Measurements. The ionization potentials (IPUPS) of the conjugated polymer films on the Cu foils were measured by UPS with a Thermo Scientific ESCALAB 250 Xi instrument. Up to five UPS measurements per sample on a different substrate location were made with a He I photon source (21.22 eV) with a pass energy of 2 eV and a 20 mA emission current, and 4 spectra were averaged and plotted in Figure S2. The surface of conjugated polymers casted on a Cu foil were electrically wired to the instrument to minimize charge build-up in the film. To identify the secondary electron cut-off (SECO), a sample bias of −10.0 V was applied to increase the vacuum level of the sample relative to that of the spectrometer. The SECO was determined from the onset of the peak with the highest binding energy. The data presented here are plotted with the Fermi edge set at 0.0 eV, and the work function was calculated by subtracting the SECO from the photon energy. The instrument was calibrated such that in situ-cleaned (Ar+ sputtered) gold foil had a work function of 5.1 eV and Fermi edge at 0.0 eV. Cyclic Voltammetry. The oxidation and reduction potentials of the conjugated polymers were extracted from CV scans measured with a BioLogic Science Instruments SP-150 potentiostat having a low current option in two electrolyte systems: the conventional system (CVC) with TBA+PF6− (0.1 M) in anhydrous acetonitrile, and the battery system (CVB) with
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Li+PF6− (1.2 M) in 3:7 (volume %) EC:EMC. For CVC, the polymers were drop-cast on a Pt working electrode (0.20 cm2), and a Pt counter electrode and an aqueous Ag/AgCl in KCl (3.0 M) reference electrode were used. The reference electrode was calibrated against the ferrocene (Fc) redox peak, which has a formal redox potential EFc of 0.630 V vs. NHE,1 to compensate for aqueous/non-aqueous junction potential.2 For CVB, a polymer-coated patterned glass/Cu electrode (0.50 cm2) was used as the working electrode (0.5 cm2) with a Li counter electrode and a separate Li reference electrode (Figure S1) in Ar atmosphere. The reference electrode was immersed in the electrolyte solution for 1 h prior to measurement to maintain steady-state corrosion for a constant redox potential. The analytes were scanned over a sweep range of 2300 to −2300 mV at 100 mV/s for CVC, and a scan rate of 10 mV/s over a sweep range of 10 to 3300 mV for CVB. The sweep ranges were adjusted for some polymers to avoid overoxidation/reduction.
CV in Battery Medium Instrumental Setup
Figure S1: Patterned glass/Cu electrode (left) and the cyclic voltammetry setup in battery media (right). WE, RE, and CE denotes working electrode, reference electrode, and counter electrode, respectively.
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UPS Spectra
Figure S2: Averaged UPS spectra of conductive polymers on Cu foil. All peaks are normalized. From bottom to top, black, red, blue, green, purple, orange, pink, and cyan spectra represent P3HT, P(3POET), P(3MEMT), PTB7, PCDTBT, DT003CF, N2200, and P(NDI-tegme2T), respectively.
Materials Syntheses The reagents 2,7-dibromo-N,N’-bis(2-ethylhexyl)naphthalenediimide3 and (4,8-bis(5-(2hexyldecyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane)4
were
synthesized according to published procedures. Other materials and reagents were purchased from Alpha Aesar, Fischer Chemical, Sigma-Aldrich, Strem Chemicals, and Trylead Chemical and were used without further purification, unless otherwise noted. Dry THF was distilled from Na/benzophenone. Column chromatography was performed using silica gel 60 M from Macherey-Nagel as the stationary phase.
2-Methoxyethyl p-Toluenesulfonate. A 500 mL round bottom flask with magnetic stirbar was charged with 10.01g p-toluenesulfonyl chloride (52.50 mmol) and 95 mL of toluene. The S5
mixture was cooled to 0oC in an ice bath, then 3.80 mL of 2-methoxyethanol (48.2 mmol) was added over 20 min. immediately after the addition of 2-methoxyethanol, 12 mL of triethylamine, dried over calcium hydride, was added over 30 min. Once the addition of triethylamine was complete, the reaction mixture was allowed to warm to room temperature and stir overnight. The precipitate was filtered off and washed with toluene. The filtrate was concentrated under reduced pressure. The resulting crude product was purified by column chromatography, eluting at 1:1 ethyl ether to hexanes (v/v), giving 9.48g of a yellow tinted oil (85.4% yield). 1H-NMR (500 MHz, chloroform-d): δ 7.80 (d, J = 8.3 Hz, 2H), 7.34 (d, J = 8.0 Hz, 2H), 4.16 (t, J = 4.8, 0.3 Hz, 2H), 3.57 (t, J = 4.8 Hz, 2H), 3.30 (s, 3H), 2.44 (s, 3H).
3-((2-Methoxyethoxy)methyl)thiophene. An oven-dried, two-neck 200 mL round bottom flask with magnetic stirbar, under Nitrogen, was charged with 600 mg sodium hydride (25.0 mmol). The side neck and top condenser joint were sealed with rubber septa. Via needle in the condenser septum, the reaction vessel was subjected to vacuum and back-filled with nitrogen three times, and then kept under nitrogen atmosphere. Next, 35 mL dry THF was added and the suspension stirred while 1.65 mL of 3-thienylmethanol (17.5 mmol) was added via syringe and needle, over 5 min. A vent needle was utilized while the reaction mixture evolved gas. Once hydrogen gas evolution ceased, 4.90 g 2-methoxyethyl p-toluenesulfonate (21.3 mmol) was added in one portion. The vent needle was removed and the reaction was headed to reflux, stirring for 24 hours. The solid was filtered off and washed several times with ethyl ether. The filtrate was condensed under reduced pressure giving the crude as an oil. The desired product was purified by a gradient column, starting with 1:4 ethyl ether in hexanes (v/v) and eluting at S6
1:1 ethyl ether in hexanes (v/v). 1.8272 g of a yellow oil were collected (60.6 % yield). 1H-NMR (500 MHz, chloroform-d): δ 7.29 (dd, J = 4.9, 3.0 Hz, 1H), 7.22 (dd, J = 3.0, 1.1 Hz, 1H), 7.09 (dd, J = 5.0, 1.3 Hz, 1H), 4.58 (s, 2H), 3.64 – 3.54 (m, 4H), 3.39 (s, 3H). 13C-NMR (125 MHz, chloroform-d) δ 139.5, 127.5, 126.0, 123.0, 72.1, 69.3, 68.6, 59.2.
2,5-Dibromo-3-((2-methoxyethoxy)methyl)thiophene. A 25 mL round bottom flask, covered
in
Al
foil
to
exclude
light,
was
charged
with
505.7
mg
3-((2-
methoxyethoxy)methyl)thiophene (2.94 mmol) and 9.6 mL of 1:1 chloroform and acetic acid (v/v). 1.671 g of N-bromosuccinimide (9.39 mmol) was then added in portions over 5 minutes, and the reaction vessel was capped with a septum and further covered in foil. After 14 hours, the reaction mixture was concentrated under reduced pressure. 15 mL of ethyl ether was added to the concentrate, and this solution was washed with 5% KOH(aq) (w/w), then water. The combined aqueous portions were extracted with ethyl ether. The collected organic portions were dried with MgSO4, filtered, and concentrated under reduced pressure. Purification via column chromatography, eluting with 1:4 ethyl ether in hexanes (v/v), gave 804.5 mg of the desired product (83.0% yield) as a yellow tinted oil. 1H NMR (500-MHz, chloroform-d) δ 7.00 (s, 1H), 4.44 (s, 2H), 3.63 – 3.54 (m, 4H), 3.39 (s, 3H). 131.0, 111.4, 110.2, 71.9, 69.7, 67.1, 59.2.
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13
C-NMR (125 MHz, chloroform-d) δ 139.3,
Poly(3-((2-methoxyethoxy)methyl)thiophene) (P3MEMT). A dry 10 mL conical vial with spin vane was charged with 171.3 mg 2,5-dibromo-3-((2-methoxyethoxy)methyl)thiophene (0.519 mmol) and purged with N2 through a silicone/Teflon septum. After 10 min, 2 mL of dry THF was added, followed by dropwise addition of 0.375 mL of 1.39 M methylmagnesium bromide in THF/toluene solution. The septum cap was replaced by a pressure seal cap, and the reaction mixture was heated to 70 oC, stirring for one hour. The reaction mixture was then cooled to room temperature, 2.3 mg dichloro(1,3-bis(diphenylphosphino)propane)nickel (0.0042 mmol) in 0.70 mL THF was added in one portion (keeping the reaction under a N2 flow), and heated back to 70 oC for 8 h. Upon cooling to room temperature, the reaction mixture was precipitated into 50 mL pentanes and filtered into a Soxhlet thimble. The precipitated polymer was purified by Soxhlet extraction in the sequence of methanol, acetone, hexanes, ethyl acetate and chloroform. The chloroform fraction was concentrated under reduced pressure and reprecipitated into hexanes. P3MEMT was collected via centrifugation and dried under vacuum (45.3 mg, 51.3% yield). Anal. calcd for (C8H10O2S)n: C 56.44, H 5.92, N 0.00.; found: C 56.11, H 5.96, N none found. GPC in trichlorobenzene, 150 oC: Mn: 9672, PDI= 1.81.
3-((2-Propoxyethyl)thiophene. An oven-dried, two-neck 200 mL round bottom flask with magnetic stirbar, under Nitrogen, was charged with 530 mg sodium hydride (22.1 mmol). The side neck and top condenser joint were sealed with rubber septa. Via needle in the condenser septum, the reaction vessel was subjected to vacuum and canceled with nitrogen three times, and then kept under nitrogen atmosphere. Next, 32 mL dry THF were added and the suspension was stirred while 1.80mL of 3-thienylethanol (16.0 mmol) was added via syringe and needle, over 5 S8
min. A vent needle was utilized while the reaction mixture evolved gas. Once hydrogen gas evolution ceased, 1.70 mL of 1-bromopropane (18.7 mmol) was added in one portion. The vent needle was removed and the reaction was headed to reflux, stirring for 24 h. The solid was filtered off and washed several times with ethyl ether. The filtrate was condensed under reduced pressure giving the crude as an oil. The desired product was purified by column chromatography, eluting with 1:4 ethyl ether in hexanes (v/v). 1.8063 g of a pink-tinted oil were collected (66.3 % yield). 1H-NMR (500 MHz, chloroform-d): δ 7.24 (dd, J = 4.9, 3.0 Hz, 1H), 7.02 (dd, J = 3.0, 1.0 Hz, 1H), 6.99 (dd, J = 4.9, 0.9 Hz, 1H), 3.64 (t, J = 7.0 Hz, 2H), 3.41 (t, J = 6.7 Hz, 2H), 2.92 (t, J = 7.0 Hz, 2H), 1.66 – 1.55 (m, 2H), 0.92 (t, J = 7.4 Hz, 3H). 13C-NMR (125 MHz, chloroformd) δ 139.5, 128.6, 125.2, 121.1, 72.8, 71.1, 30.9, 23.1, 10.7.
2,5-Dibromo-3-(2-propoxyethyl)thiophene. A 25 mL round bottom flask, covered in foil to exclude light, was charged with 380.9 mg 3-(2-propoxyethyl)thiophene (2.24 mmol) and 8.0 mL of 1:1 chloroform and acetic acid (v/v). 882.6 mg of N-bromosuccinimide (4.96 mmol) was then added in portions over 5 min, and the reaction vessel was capped with a septum and further covered in foil. After 14 h, the reaction mixture was concentrated under reduced pressure. Next, 15 mL of ethyl ether was added to the concentrate, and this solution was washed with 5% KOH(aq) (w/w), then water. The combined aqueous portions were extracted with ethyl ether. The collected organic portions were dried with MgSO4, filtered, and concentrated under reduced pressure. Purification via column chromatography, eluting with 1:4 ethyl ether in hexanes (v/v), gave 804.5 mg of the desired product (83.9% yield) as a yellow tinted oil. 1H-NMR (500 MHz,
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chloroform-d) δ 6.87 (s, 1H), 3.56 (t, J = 6.8 Hz, 2H), 3.39 (t, J = 6.7 Hz, 2H), 2.79 (t, J = 6.8 Hz, 2H), 1.64 – 1.54 (m, 2H), 0.92 (t, J = 7.4 Hz, 3H). 13C-NMR (125 MHz, chloroform-d) δ 139.8, 131.6, 110.5, 109.1, 72.8, 69.5, 30.2, 23.0, 10.7.
Poly(3-(2-propoxyethyl)thiophene) (P3POET). A dry 10 mL conical vial with spin vane was charged with 144.3 mg 2,5-dibromo-3-(2-propoxyethyl)thiophene (0.440 mmol) and purged with N2 through a silicone/Teflon septum. After 10 min, 1.7 mL of dry THF was added, followed by dropwise addition of 0.320 mL of 1.39 M methylmagnesium bromide in THF/toluene solution (0.445 mmol). The septum cap was replaced by a pressure seal cap, and the reaction mixture was heated to 70 oC, stirring for one h. The reaction mixture was then cooled to room temperature, 1.9 mg dichloro(1,3-bis(diphenylphosphino)propane)nickel (0.0035 mmol) in 0.60 mL THF was added in one portion (keeping the reaction under a N2 flow), and heated back to 70 oC for 8 h. Upon cooling to room temperature, the reaction mixture was precipitated into 50 mL pentanes and filtered into a Soxhlet thimble. The precipitated polymer was purified by Soxhlet extraction in the sequence of methanol, acetone, hexanes, ethyl acetate and chloroform. The chloroform fraction was concentrated under reduced pressure and reprecipitated into hexanes. P3POET was collected via filtration and dried under vacuum (31.1 mg, 42.0% yield). Anal. calcd for (C9H12OS)n: C 64.25, H 7.19, N 0.00.; found: C 64.19, H 7.21, N none found. GPC in trichlorobenzene, 150 oC: Mn: 10292, PDI = 1.63.
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3-(2-(2-(2-Methoxyethoxy)ethoxy)ethoxy)thiophene. A dry 200 mL two-neck round bottom flask with condenser and magnetic stir bar was charged with 5.25 g potasstium tertbutylate (46.8 mmol) and 1.17 g copper iodide (6.14 mmol) under N2 flow. Next, 15 mL anhydrous pyridine was added followed by the addition of 7.5 mL anhydrous triethylene glycol monomethyl ether, over 5 min. The reaction mixture was then allowed to stir under N2 atomosphere at room temperature for 30 min. 2.90 mL of 3-bromothiophene (30.9 mmol) was then added in one portion and the reaction mixture was heated to 100 oC under N2 for 24 h. After cooling to room temperature, the reaction mixture was concentrated under vacuum and 15 mL dichloromethane was added. This solution was washed with 5 M HCl(aq) and aqueous 10% ethylene diamine (w/w) to remove pyridine and copper, respectively. The aqueous layers were extracted with DCM, and the combined organic portions were dried with MgSO4 and concentrated under reduced pressure. The crude material was purified via column chromatography, eluting with 1:1 ethyl ether in hexanes (v/v). The desired product was isolated as a yellow tinted oil (4.38 g, 57.5% yield). 1H-NMR (500 MHz, chloroform-d): δ 7.16 (dd, J = 5.4, 3.1 Hz, 1H), 6.77 (dd, J = 5.1, 1.7 Hz, 1H), 6.25 (dd, J = 3.1, 1.6 Hz, 1H), 4.11 (t, J = 4.8 Hz, 2H), 3.84 (t, J = 4.7 Hz, 2H), 3.72 (dd, J = 6.3, 3.5 Hz, 2H), 3.70 – 3.62 (m, 4H), 3.55 (dd, J = 5.6, 3.6 Hz, 3H), 3.38 (s, 3H).
13
C-NMR (125 MHz, chloroform-d) δ 157.8, 124.9, 119.8, 97.7,
72.2, 70.9, 70.8, 70.7, 69.8, 69.7, 59.2.
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3,3'-Bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene. A dry 100 mL round bottom flask with magnetic stir bar was charged with 2.40 g 3-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)thiophene (9.76 mmol) and 20 mL of dry THF. The reaction mixture was cooled to 0o C in an ice bath over 15 min. 3.90 mL of 2.5 M n-butyllithium in hexanes (9.75 mmol) was then added dropwise over 10 min, and the reaction was stirred for two h at 0 oC. This solution was then added to a dry 250 mL two-neck round bottom flask with condenser and magnetic stir bar that had been charged with 3.46 g iron(iii) acetylacetonate (9.80 mmol) and 70 mL of dry THF. The reaction mixture was then heated to reflux and stirred for two h. After cooling the reaction to room temperature, the precipitate was filtered off and washed with ether. The filtrate was then washed with a saturated NH4Cl(aq) solution, dried with MgSO4, and concentrated under reduced pressure. The crude was purified by column chromatography, eluting with ethyl ether, giving 1.45 g of a yellow tinted oil that solidified at reduced temperature. 1H-NMR (499 MHz, chloroform-d): δ 7.09 (d, J = 5.6 Hz, 2H), 6.87 (d, J = 5.5 Hz, 2H), 4.26 (t, J = 4.9 Hz, 4H), 3.92 (dd, J = 5.5, 4.6 Hz, 4H), 3.81 – 3.76 (m, 4H), 3.72 – 3.65 (m, 8H), 3.59 – 3.54 (m, 4H), 3.39 (s, 6H).
13
C-NMR (125 MHz, chloroform-d) δ 151.8, 122.0, 116.7, 114.9, 72.1, 71.5, 71.0, 70.8,
70.7, 70.1, 59.1.
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5,5'-bis(trimethyltin)-3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene. Under N2 flow, a dry 100 mL round bottom flask with magnetic stir bar was charged with 253.8 mg 3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene (0.517 mmol) and 20 mL dry THF. The solution was cooled to -78 oC with an acetone/dry ice bath over 15 min, and then 0.440 mL n-butyllithium (1.10 mmol) was added dropwise over 10 min. The reaction mixture was allowed to stir at -78 oC for two h, warmed to room temperature for 15 min, and then cooled back down to -78 oC. 1.50 mL 1 M trimethyltin chloride in THF (1.50 mmol) was added in one portion, and the reaction was stirred and allowed to warm to room temperature overnight. After quenching with water, the organic phase was washed with a saturated brine solution and water, then dried with MgSO4 and concentrated under vacuum. The resultant solid was dissolved in a minimal amount of isopropyl alcohol and cooled to -20 oC in a freezer. After 12 h, the precipitate was collected and dried under vacuum, giving (223.3 mg, 52.3% yield) of the desired product. 1
H-NMR (500 MHz, chloroform-d) δ 6.89 (s, 2H), 4.28 (t, J = 4.9 Hz, 4H), 3.93 (dd, J = 5.5, 4.6
Hz, 4H), 3.81 – 3.75 (m, 4H), 3.72 – 3.63 (m, 8H), 3.59 – 3.54 (m, 4H), 3.39 (s, 6H). 13C-NMR (125 MHz, chloroform-d) δ 153.7, 134.0, 124.3, 120.8, 72.1, 71.6, 71.1, 70.9, 70.7, 70.3, 59.2, 8.1.
Poly(2,7-(N,N’-bis(2-ethylhexyl)-naphthalenediimide)-co-5,5’-(3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene)) (P(NDI-tegme2T)). A dry 3 mL conical vial with S13
magnetic spin vane was charged with 61.1 mg 2,7-dibromo-N,N’-bis(2-ethylhexyl)naphthalenediimide
(0.0942
mmol),
77.2
methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene
mg (0.0946
5,5'-bis(trimethyltin)-3,3'-bis(2-(2-(2mmol),
3.7
mg
bis(triphenyl-
phosphine)palladium(II) dichloride (0.0053 mmol), and purged with N2 through a silicone/Teflon septum. After 10 min, 2.3 mL of dry toluene was added and the septum cap was replaced with a pressure seal cap, under N2 flow. The polymerization was heated to 90 oC and stirred for 18 h. The reaction mixture was very viscous and was precipitated into hexanes. The precipitate was filtered into a Soxhlet thimble and subsequently Soxhlet extracted with methanol, acetone, hexanes, ethyl acetate, and chloroform. The chloroform fraction was concentrated under vacuum and precipitated into hexanes. The polymer was collected by filtration and dried under vacuum to give 64.3 g of a green solid (69.8% yield). Anal. calcd for (C52H68N2O12S2)n: C 63.91, H 7.01, N 2.78; found: C 64.10, H 6.99, N 2.78. GPC in trichlorobenzene, 150 oC: Mn: 16934, PDI: 2.08.
2,6-dihexyl-4,8-di(thiophen-2-yl)-2H-benzo[1,2-d:4,5-d']bis([1,2,3]tri-azole)-6-ium-5-ide. 21 g of TAB•4HBr (45.5 mmol) was added to 300 mL of 48 % aq. HBr and allowed to cool down to 0o C. 31.38 g of NaNO2 (454.7 mmol) was dissolved in 500 mL of deionized water and added to the reaction mixture drop-wise using an additional funnel in air. Brown gas evolved upon addition of NaNO2 solution. The reaction was allowed to warm up to room temperature overnight and then heated to 100oC for 4 hours. The mixture was subsequently cooled to room temperature where the resulting precipitate, Br2-BBTa, was filtered, washed with excessive S14
deionized water, and dried. The crude Br2-BBTa was used for the next step without further purification. The crude Br2-BBTa, 15.06 g of anhydrous K2CO3 (109.0 mmol), and 14.04 mL of 1-bromohexane (100.0 mmol) were added to 90 mL of DMF and the reaction mixture was allowed to stir at room temperature for 3 days under N2 environment. The reaction mixture was added to 500 mL of water, and the product was extracted using dichloromethane. The organic layer was collected, dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue was filtered through a short silica column using dichloromethane as the eluent yielding the crude Br2-DHBBTa. To the crude mixture, 28.9 mL of 2-(tributylstannyl)thiophene (91.0 mmol), 958 mg of Pd[PPh3]Cl2 (1.36 mmol) and 200 mL of THF were added under N2 and the reaction mixture was refluxed for 2 days. The reaction mixture was cooled to room temperature and concentrated under vacuum. The residue was dry loaded to a silica column with hexane as the
eluent.
4.2
g
of
4,8-bis(5-bromothiophen-2-yl)-2,6-dihexyl-2H-benzo[1,2-d:4,5-
d']bis([1,2,3]triazole)-6-ium-5-ide
(19
%,
red
crystalline
solids,
hexane
to
hexane:dichloromethane = 80:20) was obtained. 1H-NMR (500 MHz, chloroform-d): δ 0.90 (t, 6 H, J = 7.3 Hz), 1.26-1.52 (m, 4 H), 2.30 (quintet, 4 H, J = 7.4 Hz), 4.94 (t, 4 H, J = 7.3 Hz), 7.29 (dd, 2H, J = 4.0, 5.0 Hz), 7.55 (dd, 2 H, J =1.0, 5.0 Hz), 8.72 (dd, 2 H, J = 1.0, 5.0 Hz). 13C-NMR (125 MHz, chloroform-d): δ 14.0, 22.5, 26.3, 30.0, 31.21, 31.22, 57.8, 109.8, 127.7, 127.9, 129.5, 137.1, 141.2. Anal. calcd for C26H32N6S2: C 63.38, H 6.55, N 17.06; found: C 63.68, H 6.71, N 16.88. MALDI-TOF-MS m/z: 492.23 (M+); calcd. for C26H32N6S2 = 492.70.
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4,8-bis(5-bromothiophen-2-yl)-2,6-dihexyl-2H-benzo[1,2-d:4,5-d']bis([1,2,3]triazole)-6ium-5-ide. 2,6-dihexyl-4,8-di(thiophen-2-yl)-2H-benzo[1,2-d:4,5-d']bis([1,2,3]tri-azole)-6-ium5-ide (1.00 g, 2.03 mmol) was dissolved in 40 mL of chloroform and placed in an ice bath, was dropwise added 0.722 g of NBS (4.06 mmol) dissolved in 200 mL of chloroform. After the addition of NBS, the reaction was allowed to warm up to room temperature overnight. The reaction was quenched using aqueous Na2S2O3 and the organic layer was collected, dried over anhydrous MgSO4 and filtered. Solvent was removed using rotary evaporator and the resulting residue was purified using column chromatography (100% hexane to 80% hexane 20% dichloromethane) to yield maroon crystals (1.201 g, 91% yield).
1
H-NMR (500 MHz,
chloroform-d): δ 0.91 (t, J = 7.2 Hz, 6H), 1.52 – 1.30 (m, 13H), 2.27 (p, J = 7.3 Hz, 4H), 4.90 (t, J = 7.2 Hz, 4H), 7.22 (d, J = 4.0 Hz, 2H), 8.44 (d, J = 4.0 Hz, 2H).
13
C-NMR (125 MHz,
chloroform-d) δ 140.99, 138.82, 130.76, 129.89, 116.05, 109.24, 58.00, 31.35, 30.16, 26.46, 22.66, 14.18. Anal. calcd for C26H30Br2N6S2: C 48.01, H 4.65, N 12.92; found: C 48.39, H 4.80, N 12.87. MALDI-TOF-MS m/z: 649.96 (M+); calcd for C26H30Br2N6S2 = 650.49.
Poly[(5,5'-(4,8-bis(thien-2-yl))-2,6-(dihexyl)benzo[1,2-d;4,5-d']bis[1,2,3]triazole-alt-(4,8bis-(5-(2-hexyldecyl)thien-2-yl)benzo[1,2-b:4,5-b']dithien-2-yl)] (DT003CF). To 128 mg of 4,8-bis(5-bromothiophen-2-yl)-2,6-dihexyl-2H-benzo[1,2-d:4,5-d']bis([1,2,3]triazole)-6-ium-5ide (0.20 mmol) and 223 mg of (4,8-bis(5-(2-hexyldecyl)thiophen-2-yl)benzo[1,2-b:4,5-
S16
b']dithiophene-2,6-diyl)bis(trimethylstannane) (0.20 mmol) was added 9 mg of Pd[PPh3]4 (4 mol%) in a round-bottom flask purged with nitrogen. Next, 20 mL of dry toluene and 7 mL of dry DMF were injected into the flask and the reaction was stirred at 100oC for 1 day. The reaction mixture was allowed to cool to room temperature and was poured into 200 mL of methanol. The mixture was stirred for 3 h at room temperature and then filtered. The resulting crude polymer was purified using Soxhlet extraction using acetone, followed by hexane and lastly chloroform to yield blue solids (237 mg, 93 % yield). Anal. Calcd. for (C76H104N6S6)n: C 70.54, H 8.10, N 6.49; found: C 70.23, H 7.94, N 6.67. GPC in trichlorobenzene, 150 oC: Mn: 17851, PDI: 2.25.
REFERENCES (1) Pavlishchuk, V. V.; Addison, A. W. Conversion Constants for Redox Potentials Measured Versus Different Reference Electrodes in Acetonitrile Solutions at 25 Degrees C, Inorg. Chim. Acta, 2000, 298, 97-102. (2) Gritzner, G. In Handbook of Reference Electrodes, Inzelt, G., Lewenstam, A., Scholz, F., Eds; Springer Science & Business Media: Online, 2013; Chapter 2, pp 25-31. (3) Guo, X.; Watson, M. D. Conjugated Polymers from Naphthalene Bisimide, Org. Lett., 2008, 10, 5333-5336. (4) Zhu, Z.; Pan, H.; Drees, M.; Usta, H.; Lu, S. (Polyera Co., USA). Conjugated Polymers and Their Use in Optoelectronic Devices. PCT Int. Appl. WO2012054910A1, April, 26, 2012.
S17
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States ‡ Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States § Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Cook Hall Room 2036, Evanston, Illinois 60208, United States *Correspondence and requests for materials should be addressed to L.T. ([email protected]) and T.J.M. ([email protected]). ║ These authors contributed equally to this work.
S1
EXPERIMENTAL Synthesis of the polymers P(3MEMT), P(3POET), P(NDI-tegme2T), and DT003CF are described below. P3HT (RMI-001EE, Mw: 36-90 K, PDI: 2.0 – 2.3, RR: > 96%) was purchased from Rieke Metals, PTB7 and PCDTBT were purchased from 1-Material, and N2200 (Mn = 29.3 K, Mw: 101.7 K, PDI: 3.5) was a gift from Polyera Corp. These polymers were used as received without further purifications. Polymer film preparation. The conjugated polymers, P3HT, P(3POET), P(3MEMT), PTB7, PCDTBT, DT003CF, N2200, and P(NDI-tegme2T), were spin-coated onto Cu foil under ambient condition and onto glass/Cu substrates under Ar atmosphere. Glass substrates (1.0 cm × 2.5 cm) were sequentially cleaned in detergent, deionized water, isopropanol, and acetone for 30 min each at 50°C. Freshly cut Cu foils (1” × 1” in), and glass substrates were subsequently cleaned in a UVO cleaner (20 min). The foils were transferred to a glove box until further use and the substrates were transferred to a metal evaporator. A shadow mask with a circular electrode (0.50 cm2) as in Figure S1 was used to pattern the glass/Cu substrates with a Cu layer of ~120 nm in thickness by thermal evaporation (0.8 Å/s at 2 × 10−7 Torr). Solutions of conducting polymers were prepared in anhydrous chloroform at a concentration of 10 mg/mL under an Ar atmosphere in a glove box and were stirred overnight at 70°C to ensure complete dissolution. The polymer solutions were then applied to the Cu foils and to the patterned glass/Cu substrates by spin-coating at 1200 rpm (~100 nm) for 60 s in a dry box (relative humidity < 5%) and in a N2 filled glove box, respectively. The films on Cu foils were subsequently transferred to the glove box. Optical profilometry. The thickness of the polymer films coated on the glass/Cu substrates were estimated with a Bruker ContourGT Optical Profiler. P3HT solutions (10 mg/mL in
S2
chloroform) were spin-coated on clean glass substrates (1.0 cm × 2.5 cm) at 1200 rpm for 60 s. The center of the coated film was cleaned with an acetone-soaked Q-tip so that the bare glass substrate could be used as a baseline reference. The patterned P3HT-coated substrates were placed in the optical profilometer and the film thickness measured at 0.5× zoom. The largest difference between the clean glass surface and the thickest part of the polymer film was then calculated. Ultraviolet Photoelectron Spectroscopy (UPS) Measurements. The ionization potentials (IPUPS) of the conjugated polymer films on the Cu foils were measured by UPS with a Thermo Scientific ESCALAB 250 Xi instrument. Up to five UPS measurements per sample on a different substrate location were made with a He I photon source (21.22 eV) with a pass energy of 2 eV and a 20 mA emission current, and 4 spectra were averaged and plotted in Figure S2. The surface of conjugated polymers casted on a Cu foil were electrically wired to the instrument to minimize charge build-up in the film. To identify the secondary electron cut-off (SECO), a sample bias of −10.0 V was applied to increase the vacuum level of the sample relative to that of the spectrometer. The SECO was determined from the onset of the peak with the highest binding energy. The data presented here are plotted with the Fermi edge set at 0.0 eV, and the work function was calculated by subtracting the SECO from the photon energy. The instrument was calibrated such that in situ-cleaned (Ar+ sputtered) gold foil had a work function of 5.1 eV and Fermi edge at 0.0 eV. Cyclic Voltammetry. The oxidation and reduction potentials of the conjugated polymers were extracted from CV scans measured with a BioLogic Science Instruments SP-150 potentiostat having a low current option in two electrolyte systems: the conventional system (CVC) with TBA+PF6− (0.1 M) in anhydrous acetonitrile, and the battery system (CVB) with
S3
Li+PF6− (1.2 M) in 3:7 (volume %) EC:EMC. For CVC, the polymers were drop-cast on a Pt working electrode (0.20 cm2), and a Pt counter electrode and an aqueous Ag/AgCl in KCl (3.0 M) reference electrode were used. The reference electrode was calibrated against the ferrocene (Fc) redox peak, which has a formal redox potential EFc of 0.630 V vs. NHE,1 to compensate for aqueous/non-aqueous junction potential.2 For CVB, a polymer-coated patterned glass/Cu electrode (0.50 cm2) was used as the working electrode (0.5 cm2) with a Li counter electrode and a separate Li reference electrode (Figure S1) in Ar atmosphere. The reference electrode was immersed in the electrolyte solution for 1 h prior to measurement to maintain steady-state corrosion for a constant redox potential. The analytes were scanned over a sweep range of 2300 to −2300 mV at 100 mV/s for CVC, and a scan rate of 10 mV/s over a sweep range of 10 to 3300 mV for CVB. The sweep ranges were adjusted for some polymers to avoid overoxidation/reduction.
CV in Battery Medium Instrumental Setup
Figure S1: Patterned glass/Cu electrode (left) and the cyclic voltammetry setup in battery media (right). WE, RE, and CE denotes working electrode, reference electrode, and counter electrode, respectively.
S4
UPS Spectra
Figure S2: Averaged UPS spectra of conductive polymers on Cu foil. All peaks are normalized. From bottom to top, black, red, blue, green, purple, orange, pink, and cyan spectra represent P3HT, P(3POET), P(3MEMT), PTB7, PCDTBT, DT003CF, N2200, and P(NDI-tegme2T), respectively.
Materials Syntheses The reagents 2,7-dibromo-N,N’-bis(2-ethylhexyl)naphthalenediimide3 and (4,8-bis(5-(2hexyldecyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane)4
were
synthesized according to published procedures. Other materials and reagents were purchased from Alpha Aesar, Fischer Chemical, Sigma-Aldrich, Strem Chemicals, and Trylead Chemical and were used without further purification, unless otherwise noted. Dry THF was distilled from Na/benzophenone. Column chromatography was performed using silica gel 60 M from Macherey-Nagel as the stationary phase.
2-Methoxyethyl p-Toluenesulfonate. A 500 mL round bottom flask with magnetic stirbar was charged with 10.01g p-toluenesulfonyl chloride (52.50 mmol) and 95 mL of toluene. The S5
mixture was cooled to 0oC in an ice bath, then 3.80 mL of 2-methoxyethanol (48.2 mmol) was added over 20 min. immediately after the addition of 2-methoxyethanol, 12 mL of triethylamine, dried over calcium hydride, was added over 30 min. Once the addition of triethylamine was complete, the reaction mixture was allowed to warm to room temperature and stir overnight. The precipitate was filtered off and washed with toluene. The filtrate was concentrated under reduced pressure. The resulting crude product was purified by column chromatography, eluting at 1:1 ethyl ether to hexanes (v/v), giving 9.48g of a yellow tinted oil (85.4% yield). 1H-NMR (500 MHz, chloroform-d): δ 7.80 (d, J = 8.3 Hz, 2H), 7.34 (d, J = 8.0 Hz, 2H), 4.16 (t, J = 4.8, 0.3 Hz, 2H), 3.57 (t, J = 4.8 Hz, 2H), 3.30 (s, 3H), 2.44 (s, 3H).
3-((2-Methoxyethoxy)methyl)thiophene. An oven-dried, two-neck 200 mL round bottom flask with magnetic stirbar, under Nitrogen, was charged with 600 mg sodium hydride (25.0 mmol). The side neck and top condenser joint were sealed with rubber septa. Via needle in the condenser septum, the reaction vessel was subjected to vacuum and back-filled with nitrogen three times, and then kept under nitrogen atmosphere. Next, 35 mL dry THF was added and the suspension stirred while 1.65 mL of 3-thienylmethanol (17.5 mmol) was added via syringe and needle, over 5 min. A vent needle was utilized while the reaction mixture evolved gas. Once hydrogen gas evolution ceased, 4.90 g 2-methoxyethyl p-toluenesulfonate (21.3 mmol) was added in one portion. The vent needle was removed and the reaction was headed to reflux, stirring for 24 hours. The solid was filtered off and washed several times with ethyl ether. The filtrate was condensed under reduced pressure giving the crude as an oil. The desired product was purified by a gradient column, starting with 1:4 ethyl ether in hexanes (v/v) and eluting at S6
1:1 ethyl ether in hexanes (v/v). 1.8272 g of a yellow oil were collected (60.6 % yield). 1H-NMR (500 MHz, chloroform-d): δ 7.29 (dd, J = 4.9, 3.0 Hz, 1H), 7.22 (dd, J = 3.0, 1.1 Hz, 1H), 7.09 (dd, J = 5.0, 1.3 Hz, 1H), 4.58 (s, 2H), 3.64 – 3.54 (m, 4H), 3.39 (s, 3H). 13C-NMR (125 MHz, chloroform-d) δ 139.5, 127.5, 126.0, 123.0, 72.1, 69.3, 68.6, 59.2.
2,5-Dibromo-3-((2-methoxyethoxy)methyl)thiophene. A 25 mL round bottom flask, covered
in
Al
foil
to
exclude
light,
was
charged
with
505.7
mg
3-((2-
methoxyethoxy)methyl)thiophene (2.94 mmol) and 9.6 mL of 1:1 chloroform and acetic acid (v/v). 1.671 g of N-bromosuccinimide (9.39 mmol) was then added in portions over 5 minutes, and the reaction vessel was capped with a septum and further covered in foil. After 14 hours, the reaction mixture was concentrated under reduced pressure. 15 mL of ethyl ether was added to the concentrate, and this solution was washed with 5% KOH(aq) (w/w), then water. The combined aqueous portions were extracted with ethyl ether. The collected organic portions were dried with MgSO4, filtered, and concentrated under reduced pressure. Purification via column chromatography, eluting with 1:4 ethyl ether in hexanes (v/v), gave 804.5 mg of the desired product (83.0% yield) as a yellow tinted oil. 1H NMR (500-MHz, chloroform-d) δ 7.00 (s, 1H), 4.44 (s, 2H), 3.63 – 3.54 (m, 4H), 3.39 (s, 3H). 131.0, 111.4, 110.2, 71.9, 69.7, 67.1, 59.2.
S7
13
C-NMR (125 MHz, chloroform-d) δ 139.3,
Poly(3-((2-methoxyethoxy)methyl)thiophene) (P3MEMT). A dry 10 mL conical vial with spin vane was charged with 171.3 mg 2,5-dibromo-3-((2-methoxyethoxy)methyl)thiophene (0.519 mmol) and purged with N2 through a silicone/Teflon septum. After 10 min, 2 mL of dry THF was added, followed by dropwise addition of 0.375 mL of 1.39 M methylmagnesium bromide in THF/toluene solution. The septum cap was replaced by a pressure seal cap, and the reaction mixture was heated to 70 oC, stirring for one hour. The reaction mixture was then cooled to room temperature, 2.3 mg dichloro(1,3-bis(diphenylphosphino)propane)nickel (0.0042 mmol) in 0.70 mL THF was added in one portion (keeping the reaction under a N2 flow), and heated back to 70 oC for 8 h. Upon cooling to room temperature, the reaction mixture was precipitated into 50 mL pentanes and filtered into a Soxhlet thimble. The precipitated polymer was purified by Soxhlet extraction in the sequence of methanol, acetone, hexanes, ethyl acetate and chloroform. The chloroform fraction was concentrated under reduced pressure and reprecipitated into hexanes. P3MEMT was collected via centrifugation and dried under vacuum (45.3 mg, 51.3% yield). Anal. calcd for (C8H10O2S)n: C 56.44, H 5.92, N 0.00.; found: C 56.11, H 5.96, N none found. GPC in trichlorobenzene, 150 oC: Mn: 9672, PDI= 1.81.
3-((2-Propoxyethyl)thiophene. An oven-dried, two-neck 200 mL round bottom flask with magnetic stirbar, under Nitrogen, was charged with 530 mg sodium hydride (22.1 mmol). The side neck and top condenser joint were sealed with rubber septa. Via needle in the condenser septum, the reaction vessel was subjected to vacuum and canceled with nitrogen three times, and then kept under nitrogen atmosphere. Next, 32 mL dry THF were added and the suspension was stirred while 1.80mL of 3-thienylethanol (16.0 mmol) was added via syringe and needle, over 5 S8
min. A vent needle was utilized while the reaction mixture evolved gas. Once hydrogen gas evolution ceased, 1.70 mL of 1-bromopropane (18.7 mmol) was added in one portion. The vent needle was removed and the reaction was headed to reflux, stirring for 24 h. The solid was filtered off and washed several times with ethyl ether. The filtrate was condensed under reduced pressure giving the crude as an oil. The desired product was purified by column chromatography, eluting with 1:4 ethyl ether in hexanes (v/v). 1.8063 g of a pink-tinted oil were collected (66.3 % yield). 1H-NMR (500 MHz, chloroform-d): δ 7.24 (dd, J = 4.9, 3.0 Hz, 1H), 7.02 (dd, J = 3.0, 1.0 Hz, 1H), 6.99 (dd, J = 4.9, 0.9 Hz, 1H), 3.64 (t, J = 7.0 Hz, 2H), 3.41 (t, J = 6.7 Hz, 2H), 2.92 (t, J = 7.0 Hz, 2H), 1.66 – 1.55 (m, 2H), 0.92 (t, J = 7.4 Hz, 3H). 13C-NMR (125 MHz, chloroformd) δ 139.5, 128.6, 125.2, 121.1, 72.8, 71.1, 30.9, 23.1, 10.7.
2,5-Dibromo-3-(2-propoxyethyl)thiophene. A 25 mL round bottom flask, covered in foil to exclude light, was charged with 380.9 mg 3-(2-propoxyethyl)thiophene (2.24 mmol) and 8.0 mL of 1:1 chloroform and acetic acid (v/v). 882.6 mg of N-bromosuccinimide (4.96 mmol) was then added in portions over 5 min, and the reaction vessel was capped with a septum and further covered in foil. After 14 h, the reaction mixture was concentrated under reduced pressure. Next, 15 mL of ethyl ether was added to the concentrate, and this solution was washed with 5% KOH(aq) (w/w), then water. The combined aqueous portions were extracted with ethyl ether. The collected organic portions were dried with MgSO4, filtered, and concentrated under reduced pressure. Purification via column chromatography, eluting with 1:4 ethyl ether in hexanes (v/v), gave 804.5 mg of the desired product (83.9% yield) as a yellow tinted oil. 1H-NMR (500 MHz,
S9
chloroform-d) δ 6.87 (s, 1H), 3.56 (t, J = 6.8 Hz, 2H), 3.39 (t, J = 6.7 Hz, 2H), 2.79 (t, J = 6.8 Hz, 2H), 1.64 – 1.54 (m, 2H), 0.92 (t, J = 7.4 Hz, 3H). 13C-NMR (125 MHz, chloroform-d) δ 139.8, 131.6, 110.5, 109.1, 72.8, 69.5, 30.2, 23.0, 10.7.
Poly(3-(2-propoxyethyl)thiophene) (P3POET). A dry 10 mL conical vial with spin vane was charged with 144.3 mg 2,5-dibromo-3-(2-propoxyethyl)thiophene (0.440 mmol) and purged with N2 through a silicone/Teflon septum. After 10 min, 1.7 mL of dry THF was added, followed by dropwise addition of 0.320 mL of 1.39 M methylmagnesium bromide in THF/toluene solution (0.445 mmol). The septum cap was replaced by a pressure seal cap, and the reaction mixture was heated to 70 oC, stirring for one h. The reaction mixture was then cooled to room temperature, 1.9 mg dichloro(1,3-bis(diphenylphosphino)propane)nickel (0.0035 mmol) in 0.60 mL THF was added in one portion (keeping the reaction under a N2 flow), and heated back to 70 oC for 8 h. Upon cooling to room temperature, the reaction mixture was precipitated into 50 mL pentanes and filtered into a Soxhlet thimble. The precipitated polymer was purified by Soxhlet extraction in the sequence of methanol, acetone, hexanes, ethyl acetate and chloroform. The chloroform fraction was concentrated under reduced pressure and reprecipitated into hexanes. P3POET was collected via filtration and dried under vacuum (31.1 mg, 42.0% yield). Anal. calcd for (C9H12OS)n: C 64.25, H 7.19, N 0.00.; found: C 64.19, H 7.21, N none found. GPC in trichlorobenzene, 150 oC: Mn: 10292, PDI = 1.63.
S10
3-(2-(2-(2-Methoxyethoxy)ethoxy)ethoxy)thiophene. A dry 200 mL two-neck round bottom flask with condenser and magnetic stir bar was charged with 5.25 g potasstium tertbutylate (46.8 mmol) and 1.17 g copper iodide (6.14 mmol) under N2 flow. Next, 15 mL anhydrous pyridine was added followed by the addition of 7.5 mL anhydrous triethylene glycol monomethyl ether, over 5 min. The reaction mixture was then allowed to stir under N2 atomosphere at room temperature for 30 min. 2.90 mL of 3-bromothiophene (30.9 mmol) was then added in one portion and the reaction mixture was heated to 100 oC under N2 for 24 h. After cooling to room temperature, the reaction mixture was concentrated under vacuum and 15 mL dichloromethane was added. This solution was washed with 5 M HCl(aq) and aqueous 10% ethylene diamine (w/w) to remove pyridine and copper, respectively. The aqueous layers were extracted with DCM, and the combined organic portions were dried with MgSO4 and concentrated under reduced pressure. The crude material was purified via column chromatography, eluting with 1:1 ethyl ether in hexanes (v/v). The desired product was isolated as a yellow tinted oil (4.38 g, 57.5% yield). 1H-NMR (500 MHz, chloroform-d): δ 7.16 (dd, J = 5.4, 3.1 Hz, 1H), 6.77 (dd, J = 5.1, 1.7 Hz, 1H), 6.25 (dd, J = 3.1, 1.6 Hz, 1H), 4.11 (t, J = 4.8 Hz, 2H), 3.84 (t, J = 4.7 Hz, 2H), 3.72 (dd, J = 6.3, 3.5 Hz, 2H), 3.70 – 3.62 (m, 4H), 3.55 (dd, J = 5.6, 3.6 Hz, 3H), 3.38 (s, 3H).
13
C-NMR (125 MHz, chloroform-d) δ 157.8, 124.9, 119.8, 97.7,
72.2, 70.9, 70.8, 70.7, 69.8, 69.7, 59.2.
S11
3,3'-Bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene. A dry 100 mL round bottom flask with magnetic stir bar was charged with 2.40 g 3-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)thiophene (9.76 mmol) and 20 mL of dry THF. The reaction mixture was cooled to 0o C in an ice bath over 15 min. 3.90 mL of 2.5 M n-butyllithium in hexanes (9.75 mmol) was then added dropwise over 10 min, and the reaction was stirred for two h at 0 oC. This solution was then added to a dry 250 mL two-neck round bottom flask with condenser and magnetic stir bar that had been charged with 3.46 g iron(iii) acetylacetonate (9.80 mmol) and 70 mL of dry THF. The reaction mixture was then heated to reflux and stirred for two h. After cooling the reaction to room temperature, the precipitate was filtered off and washed with ether. The filtrate was then washed with a saturated NH4Cl(aq) solution, dried with MgSO4, and concentrated under reduced pressure. The crude was purified by column chromatography, eluting with ethyl ether, giving 1.45 g of a yellow tinted oil that solidified at reduced temperature. 1H-NMR (499 MHz, chloroform-d): δ 7.09 (d, J = 5.6 Hz, 2H), 6.87 (d, J = 5.5 Hz, 2H), 4.26 (t, J = 4.9 Hz, 4H), 3.92 (dd, J = 5.5, 4.6 Hz, 4H), 3.81 – 3.76 (m, 4H), 3.72 – 3.65 (m, 8H), 3.59 – 3.54 (m, 4H), 3.39 (s, 6H).
13
C-NMR (125 MHz, chloroform-d) δ 151.8, 122.0, 116.7, 114.9, 72.1, 71.5, 71.0, 70.8,
70.7, 70.1, 59.1.
S12
5,5'-bis(trimethyltin)-3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene. Under N2 flow, a dry 100 mL round bottom flask with magnetic stir bar was charged with 253.8 mg 3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene (0.517 mmol) and 20 mL dry THF. The solution was cooled to -78 oC with an acetone/dry ice bath over 15 min, and then 0.440 mL n-butyllithium (1.10 mmol) was added dropwise over 10 min. The reaction mixture was allowed to stir at -78 oC for two h, warmed to room temperature for 15 min, and then cooled back down to -78 oC. 1.50 mL 1 M trimethyltin chloride in THF (1.50 mmol) was added in one portion, and the reaction was stirred and allowed to warm to room temperature overnight. After quenching with water, the organic phase was washed with a saturated brine solution and water, then dried with MgSO4 and concentrated under vacuum. The resultant solid was dissolved in a minimal amount of isopropyl alcohol and cooled to -20 oC in a freezer. After 12 h, the precipitate was collected and dried under vacuum, giving (223.3 mg, 52.3% yield) of the desired product. 1
H-NMR (500 MHz, chloroform-d) δ 6.89 (s, 2H), 4.28 (t, J = 4.9 Hz, 4H), 3.93 (dd, J = 5.5, 4.6
Hz, 4H), 3.81 – 3.75 (m, 4H), 3.72 – 3.63 (m, 8H), 3.59 – 3.54 (m, 4H), 3.39 (s, 6H). 13C-NMR (125 MHz, chloroform-d) δ 153.7, 134.0, 124.3, 120.8, 72.1, 71.6, 71.1, 70.9, 70.7, 70.3, 59.2, 8.1.
Poly(2,7-(N,N’-bis(2-ethylhexyl)-naphthalenediimide)-co-5,5’-(3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene)) (P(NDI-tegme2T)). A dry 3 mL conical vial with S13
magnetic spin vane was charged with 61.1 mg 2,7-dibromo-N,N’-bis(2-ethylhexyl)naphthalenediimide
(0.0942
mmol),
77.2
methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene
mg (0.0946
5,5'-bis(trimethyltin)-3,3'-bis(2-(2-(2mmol),
3.7
mg
bis(triphenyl-
phosphine)palladium(II) dichloride (0.0053 mmol), and purged with N2 through a silicone/Teflon septum. After 10 min, 2.3 mL of dry toluene was added and the septum cap was replaced with a pressure seal cap, under N2 flow. The polymerization was heated to 90 oC and stirred for 18 h. The reaction mixture was very viscous and was precipitated into hexanes. The precipitate was filtered into a Soxhlet thimble and subsequently Soxhlet extracted with methanol, acetone, hexanes, ethyl acetate, and chloroform. The chloroform fraction was concentrated under vacuum and precipitated into hexanes. The polymer was collected by filtration and dried under vacuum to give 64.3 g of a green solid (69.8% yield). Anal. calcd for (C52H68N2O12S2)n: C 63.91, H 7.01, N 2.78; found: C 64.10, H 6.99, N 2.78. GPC in trichlorobenzene, 150 oC: Mn: 16934, PDI: 2.08.
2,6-dihexyl-4,8-di(thiophen-2-yl)-2H-benzo[1,2-d:4,5-d']bis([1,2,3]tri-azole)-6-ium-5-ide. 21 g of TAB•4HBr (45.5 mmol) was added to 300 mL of 48 % aq. HBr and allowed to cool down to 0o C. 31.38 g of NaNO2 (454.7 mmol) was dissolved in 500 mL of deionized water and added to the reaction mixture drop-wise using an additional funnel in air. Brown gas evolved upon addition of NaNO2 solution. The reaction was allowed to warm up to room temperature overnight and then heated to 100oC for 4 hours. The mixture was subsequently cooled to room temperature where the resulting precipitate, Br2-BBTa, was filtered, washed with excessive S14
deionized water, and dried. The crude Br2-BBTa was used for the next step without further purification. The crude Br2-BBTa, 15.06 g of anhydrous K2CO3 (109.0 mmol), and 14.04 mL of 1-bromohexane (100.0 mmol) were added to 90 mL of DMF and the reaction mixture was allowed to stir at room temperature for 3 days under N2 environment. The reaction mixture was added to 500 mL of water, and the product was extracted using dichloromethane. The organic layer was collected, dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue was filtered through a short silica column using dichloromethane as the eluent yielding the crude Br2-DHBBTa. To the crude mixture, 28.9 mL of 2-(tributylstannyl)thiophene (91.0 mmol), 958 mg of Pd[PPh3]Cl2 (1.36 mmol) and 200 mL of THF were added under N2 and the reaction mixture was refluxed for 2 days. The reaction mixture was cooled to room temperature and concentrated under vacuum. The residue was dry loaded to a silica column with hexane as the
eluent.
4.2
g
of
4,8-bis(5-bromothiophen-2-yl)-2,6-dihexyl-2H-benzo[1,2-d:4,5-
d']bis([1,2,3]triazole)-6-ium-5-ide
(19
%,
red
crystalline
solids,
hexane
to
hexane:dichloromethane = 80:20) was obtained. 1H-NMR (500 MHz, chloroform-d): δ 0.90 (t, 6 H, J = 7.3 Hz), 1.26-1.52 (m, 4 H), 2.30 (quintet, 4 H, J = 7.4 Hz), 4.94 (t, 4 H, J = 7.3 Hz), 7.29 (dd, 2H, J = 4.0, 5.0 Hz), 7.55 (dd, 2 H, J =1.0, 5.0 Hz), 8.72 (dd, 2 H, J = 1.0, 5.0 Hz). 13C-NMR (125 MHz, chloroform-d): δ 14.0, 22.5, 26.3, 30.0, 31.21, 31.22, 57.8, 109.8, 127.7, 127.9, 129.5, 137.1, 141.2. Anal. calcd for C26H32N6S2: C 63.38, H 6.55, N 17.06; found: C 63.68, H 6.71, N 16.88. MALDI-TOF-MS m/z: 492.23 (M+); calcd. for C26H32N6S2 = 492.70.
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4,8-bis(5-bromothiophen-2-yl)-2,6-dihexyl-2H-benzo[1,2-d:4,5-d']bis([1,2,3]triazole)-6ium-5-ide. 2,6-dihexyl-4,8-di(thiophen-2-yl)-2H-benzo[1,2-d:4,5-d']bis([1,2,3]tri-azole)-6-ium5-ide (1.00 g, 2.03 mmol) was dissolved in 40 mL of chloroform and placed in an ice bath, was dropwise added 0.722 g of NBS (4.06 mmol) dissolved in 200 mL of chloroform. After the addition of NBS, the reaction was allowed to warm up to room temperature overnight. The reaction was quenched using aqueous Na2S2O3 and the organic layer was collected, dried over anhydrous MgSO4 and filtered. Solvent was removed using rotary evaporator and the resulting residue was purified using column chromatography (100% hexane to 80% hexane 20% dichloromethane) to yield maroon crystals (1.201 g, 91% yield).
1
H-NMR (500 MHz,
chloroform-d): δ 0.91 (t, J = 7.2 Hz, 6H), 1.52 – 1.30 (m, 13H), 2.27 (p, J = 7.3 Hz, 4H), 4.90 (t, J = 7.2 Hz, 4H), 7.22 (d, J = 4.0 Hz, 2H), 8.44 (d, J = 4.0 Hz, 2H).
13
C-NMR (125 MHz,
chloroform-d) δ 140.99, 138.82, 130.76, 129.89, 116.05, 109.24, 58.00, 31.35, 30.16, 26.46, 22.66, 14.18. Anal. calcd for C26H30Br2N6S2: C 48.01, H 4.65, N 12.92; found: C 48.39, H 4.80, N 12.87. MALDI-TOF-MS m/z: 649.96 (M+); calcd for C26H30Br2N6S2 = 650.49.
Poly[(5,5'-(4,8-bis(thien-2-yl))-2,6-(dihexyl)benzo[1,2-d;4,5-d']bis[1,2,3]triazole-alt-(4,8bis-(5-(2-hexyldecyl)thien-2-yl)benzo[1,2-b:4,5-b']dithien-2-yl)] (DT003CF). To 128 mg of 4,8-bis(5-bromothiophen-2-yl)-2,6-dihexyl-2H-benzo[1,2-d:4,5-d']bis([1,2,3]triazole)-6-ium-5ide (0.20 mmol) and 223 mg of (4,8-bis(5-(2-hexyldecyl)thiophen-2-yl)benzo[1,2-b:4,5-
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b']dithiophene-2,6-diyl)bis(trimethylstannane) (0.20 mmol) was added 9 mg of Pd[PPh3]4 (4 mol%) in a round-bottom flask purged with nitrogen. Next, 20 mL of dry toluene and 7 mL of dry DMF were injected into the flask and the reaction was stirred at 100oC for 1 day. The reaction mixture was allowed to cool to room temperature and was poured into 200 mL of methanol. The mixture was stirred for 3 h at room temperature and then filtered. The resulting crude polymer was purified using Soxhlet extraction using acetone, followed by hexane and lastly chloroform to yield blue solids (237 mg, 93 % yield). Anal. Calcd. for (C76H104N6S6)n: C 70.54, H 8.10, N 6.49; found: C 70.23, H 7.94, N 6.67. GPC in trichlorobenzene, 150 oC: Mn: 17851, PDI: 2.25.
REFERENCES (1) Pavlishchuk, V. V.; Addison, A. W. Conversion Constants for Redox Potentials Measured Versus Different Reference Electrodes in Acetonitrile Solutions at 25 Degrees C, Inorg. Chim. Acta, 2000, 298, 97-102. (2) Gritzner, G. In Handbook of Reference Electrodes, Inzelt, G., Lewenstam, A., Scholz, F., Eds; Springer Science & Business Media: Online, 2013; Chapter 2, pp 25-31. (3) Guo, X.; Watson, M. D. Conjugated Polymers from Naphthalene Bisimide, Org. Lett., 2008, 10, 5333-5336. (4) Zhu, Z.; Pan, H.; Drees, M.; Usta, H.; Lu, S. (Polyera Co., USA). Conjugated Polymers and Their Use in Optoelectronic Devices. PCT Int. Appl. WO2012054910A1, April, 26, 2012.
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