Synthesis and Characterization of Polyelectrolytes Based on Benzotriazole Backbone

Supporting Information

Synthesis and Characterization of Polyelectrolytes based on Benzotriazole Backbone

Yueqin Shi1*, Yaguang Kong1,Lihui Song1,Jun Zhang1, Zhenguo Ji1, Ziyi Ge2*

1College of materials & environmental engineering, Hangzhou Dianzi University, Xiasha Higher Education Zone, 310018, P. R. China

2Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences, Ningbo 315201, P. R. China

1

Synthesis of the monomers

Synthesis of 2-(C4H8SO3Na)-2H-benzo[1,2,3]triazole

Benzotriazole (28.6 mmol, 3.4 g) and tetrabutylammonium bromide (460 mg, 1.43 mmol) are dissolved in anhydrous DMSO (140 mL), which is degassed by N2 for 5 min. NaOH (14 g, 16 mL) aqueous solution is added via syringe. Then 1,4-butanesultone (3500 μL, 66.8 mmol) is added. After stirring for 3 hours at room temperature, the reaction mixture is poured into acetone. Through filtration and washed with acetone, a white precipitate is obtained. The product is purified by chromatography (reversed phase silica gel C-18, 10:1 H2O:MeOH) to provide the white solid with 41% yield. 1H NMR (500 MHz, D2O) δ 7.53 (d, 2H), 7.86 (d, 2H), 4.79 (t, 2H),2.89 (t, 2H), 2.24 (m, 2H), 1.74 (m, 2H). MS m/z calcd for C10H12N3SO3Na: 277 g/mol, found: 254 (C10H12N3SO3-).

Synthesis of 4,7-dibromo-2-(C4H8SO3Na)-2H-benzo[1,2,3]triazole

BTN-C4H8SO3Na (0.73 mmol, 0.201 g) and an aqueous HBr solution (33 wt%, 1.3 mL) are added to the flask, which is stirred for one hour at 100ºC. Cooling the mixture to room temperature, bromine (0.33 g, 0.106 mL) is added. Then the solution is heated to 80ºC. 12 hours later,cooling down the reaction to room temperature again, an aqueous solution of NaHCO3 is added. The product is purified by chromatography (reversed phase silica gel C-18, 10:1 H2O:MeOH) to provide the white solid 4 with 83% yield. 1H NMR (400 MHz, D2O) δ 7.59 (s, 2H), 4.88 (t, 2H),2.90 (t, 2H), 2.25 (m, 2H), 1.74 (m, 2H). MS m/z calcd for C10H10Br2N3SO3Na: 435 g/mol, found: 411.7 (C10H10Br2N3SO3-).

Synthesis of1,2-diamino-3,6-dibromobenzene

NaBH4 (20 mmol, 0.76 g) was added tothe solution of 4,7-dibromo-benzo[1,2,5]thiadiazole (2 mmol, 0.588g) in 20 mL EtOH at 0 ºC. After stirring for 1 hour, the reaction was processed overnight. After removing the EtOH, the extraction was conducted with ether and water. The 1,2-diamino-3,6-dibromobenzene could be obtained after drying the organic phase with 80% yield. 1H NMR (500 MHz, CD3OD): δ= 6.5 (s, 2H)

Synthesis of4,7-dibromo-1,2,3-benzotriazole

The aqueous solution of NaNO2 (0.15 g, 1.65 mmol, 3 mL) is added to the solution of 1,2-diamino-3,6-dibromobenzene (0.4 g, 1.5 mmol) in CH3COOH (6 mL). After stirring for 30 min at room temperature, precipitate is filtered and washed with water to afford 4,7-dibromo-1,2,3-benzotriazole (0.38 g) as a pink powder (yield is 85%). 1H NMR (500 MHz, CD3OD): δ= 7.56 (s, 2H)

Synthesis of 4,7-dibromo-2-(4-bromo-butyl)-2H-benzotriazole

4,7-Dibromo-1,2,3-benzotriazole (1.45 mmol, 0.4 g) and t-BuOK (4.1 mmol, 0.46 g) are dissolved in 20 mL MeOH. At 60 ºC, 1,6-dibromobutane (14.5 mmol) is added to the solution. After stirring for 5 hours, the MeOH is removed and extraction is conducted with CF and water. Drying the organic phase, the product is purified by chromatography (CF:Hexane = 1:1 vol) and the yield is 58%. 1H NMR (500 MHz, CD3OD): δ= 7.46 (s, 2H), δ= 4.86 (N-CH2, 2H), δ= 3.49 (Br-CH2, 2H), δ= 2.29 (CH2-CH2, 4H).

Synthesis of 4,7-dibromo-2-(6-bromo-hexyl)-2H-benzotriazole

4,7-Dibromo-1,2,3-benzotriazole (1.45 mmol, 0.4 g) and t-BuOK (4.1 mmol, 0.46 g) were dissolved in 20 mL MeOH. At 60 ºC, 1,6-dibromohexane (14.5 mmol) was added to the solution. After stirring for 5 hours, the MeOH was removed and the residue was extracted with CHCl3 and water. After concentration, purification by chromatography (CHCl3:hexane = 1:1 vol) provided BTz-Br (0.37 g) in 59% yield. 1H NMR (500 MHz, CDCl3): δ = 7.43 (s, 2H), 4.81 (N-CH2, 2H), 3.41 (Br-CH2, 2H), 2.2 (-CH2-, 2H), 1.84 (-CH2-, 2H), 1.5 (-CH2-, 2H), 1.42 (-CH2-, 2H).

Synthesis of ionic-functionalized monomers

The monomers with bromo-end side chain are stirred in pyridine or trimethylamine at 60 ºC for 2 days. Methanol is added to aid dissolution of ionic species. The volatiles are removed and the ionic-functionalized monomers can be dried over night at low pressure (99% yield).

1H NMR (500 MHz, CD3OD) for monomer with pyridine-end side chain: δ = 9.0 (s, 2H), 8.62 (s, 1H), 8.13 (s, 2H), 7.53 (s, 2H), 4.9 (N-CH2-, 2H), 4.72 (N+-CH2-, 2H), 2.25 (-CH2-, 2H), 2.10 (-CH2-, 2H), 1.50 (-CH2-, 2H), 1.35 (-CH2-, 2H).

1H NMR (500 MHz, CD3OD)for monomer with ammonium-end side chain 3: δ = 7.51 (s, 2H), 4.9 (N-CH2-, 2H), 3.42 (N+-CH2-, 2H), 3.12 (-N(CH3)3, 9H), 2.24 (-CH2-, 2H), 1.89 (-CH2-, 2H), 1.51 (-CH2-, 2H), 1.29 (-CH2-, 2H).

Experimental section

Suzuki coupling polymerization ofPBTBTz-TMABr, PBTBTz-PyrBr

Compound 2 (1.0 equiv), 1 (1.0 equiv) and Pd(PPh3)4 (2 mol%) were dissolved in THF in microwave tube at glove box. Then the tube was sealed and taken out of the glove box. The aqueous Na2CO3 was degassed and injected into the tube. The reaction was stirred at 80 ºC for 24 h, then pouring into methanol. Red precipitate was collected by filtration and washed with acetone and MeOH. The red precipitated solid was subjected to Soxhlet extraction with acetone and hexane sequently. The residue was dissolved in CHCl3, which was named PBTBTz-Br. The CPEs were synthesized by placing PBTBTz-Br into trimethylamineor pyridine solution at 60 ºC for 24 h. PBTBTz-TMABr and PBTBTz-PyrBr were obtained through rotate evaporation from their solutions.

Suzuki coupling polymerization ofand PBTBTz-SO3Na

Dibromide 3 (1.0 equiv), diboronic ester 4 (1.0 equiv), Na2CO3 (5 equiv), and Pd(PPh3)4 (2 mol%) were combined in the microwave tube with a stir bar at glove box. The tube was sealed and taken out of the glove box. A mixture of DMF and H2O (4/1 vol/vol) was degassed by argon for 5 min, then transferred into the above tube under argon atmosphere. The solution was placed into an oil bath, and heated to 80 ºC, at which temperature the mixture turned dark red in ~20 min. Reaction was conducted at about 80 ºC for 24 h, and poured into acetone. Red precipitate was collected by filtration and washed with acetone and MeOH. The red products were dissolved in millipore H2O and then transferred into a dialysis tube (MWCO: 3500-5000). The tube was placed into the millipore H2O for dialysis in a week and the millipore H2O was changed every 12 h. After freeze-drying, the PBTBTz-SO3Na was obtained as dark red solid.

Yamamoto Polymerizations of PBTz-PyrBr, PBTz-TMABr and PBTz-SO3Na

An equimolecular amount of dibromo-monomer (1 equiv) was added to the solution of bis(1,5-cyclooctadiene)nickel(0) (1 equiv), 2,2-bipyridine (1 equiv), and 1,5-cyclooctadiene (1 equiv) at 60 ºC under argon. The mixture was stirred vigorously at 65 ºC for two days under argon. After cooling to room temperature, the mixture was poured into chloroform. The precipitate was washed with chloroform, acetone, and hexane by Soxhlet extraction, and followed by dissolution in Millipore water. Finally, the solution was purified in dialysis tube (MWCO = 3500-5000 Da) that was soaked in Millipore water for 5 days. The water was changed every 12 h. After freeze drying, CPEs were obtained as red solids.

Characterizations

General Information for Synthesis

All glasses are oven-dried. The chemicals are commercially available and are used as received. Thin layer chromatography (TLC) is performed using EM Science Silica Gel 60 F254 glass plates. Flash chromatography is performed using 60 Å silica gel (37-75 µm). The dialysis membrane (MWCO: 3500-5000 Da) is purchased from Spectrum® Laboratories Inc. 1H NMR spectra are recorded at either 400 MHz or 500 MHz in D2O, CDCl3 or CD3OD. The GPC measurements of PBTz-PyrBr and PBTz-TMABr are conducted on Alliance HPLC using pure water as solvent with PEG (standard) under the condition of column temperature at 40 ºC and a flow rate of 1.0 mL/minat Shanghai Institute of Organic Chemistry, China. The GPC of PBTz-Br is measured in Waters® system using CHCl3 as the solvent. The GPC of PBTBTz-SO3TBA is measured using DMF as the solvent at University of California, Santa Barbara.

Cyclic voltammetry (CV) measurements

The cyclic voltammetry (CV) is performed using CHI instrument model 730B in a standard three-electrode at University of California, Santa Barbara, one compartment configuration equipped with Ag wire quasi reference electrode, Pt wire counter electrode, and glassy carbon working electrode. And the glass carbon electrodes are polished with alumina. The polyelectrolytes are formed the films by dripping 5 μL of 5 mg/mL solution on the carbon working electrode, then dried under vacuum overnight before measurements. The CV experiments are processed in anhydrous acetonitrile solution (PBTz-SO3Na and PBTBTz-SO3Na are performed in DMF) with 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte at scan rate 100 mV/s. The electrochemical solutions are purged with argon for 15 minutes to deoxygenate the solutions. Ferrocene is used as the internal standard. The highest occupied molecular orbital (HOMO) energy of PBTBTz-SO3Na, PBTz-PyrBr, PBTz-TMABr and PBTz-SO3Na were -5.29 eV, -5.45 eV, -5.22 eV and -5.51 eV respectively.And lowest unoccupied molecular orbital (LUMO) energy of PBTBTz-SO3Na, PBTz-PyrBr, PBTz-TMABr and PBTz-SO3Na were -3.43 eV, -3.3 eV, -3.1 eV and -3.05 eV respectively.

UV-vis absorptions

The UV-vis absorption measurements are performed using a Perkin Elmer Lambda 750 spectrophotometer at University of California, Santa Barbara. Films are prepared by spin-coating from the corresponding solutions (5 mg/mL) onto the glass substrates.The concentration of solution is 0.0167 mg/mL.

Dynamic Light Scattering (DLS)

Dynamic light scattering measurements are taken using a DynaPro NanoStar with Dynamics software for data collection and analysis from Wyatt Technology. Measurements are carried out using a He-Ne laser at a wavelength of 658 nm at room temperature. The concentration of each sample is 0.0167 mg/mL. An autocorrelation function is determined using the provided software to fit the data. The diffusion coefficient is extracted from the autocorrelation function such that the hydrodynamic radius is calculated using the Stokes-Einstein equation. All the DLS data are displayed in the tables of Supporting Information (SI).

Scheme S1. The synthesis of PBTBTz-TMABr and PBTBTz-PyrBr. Reaction conditions: (i) 1,4-dibromobutane, KOH, 60 ºC, 5 h; (ii) Pd(PPh3)4, Na2CO3, THF/H2O, 90 ºC, 24 h; And (iii) THF/H2O, NMe3 orpyridine.

Figure S1. The GPC plots of the PBTBTz-Br.

Figure S2. The GPC plots of the PBTBTz-SO3Na.

Figure S3. The CV of PBTBTz-SO3Na.

Figure S4. The CV of PBTz-PyrBr,PBTz-TMABr and PBTz-SO3Na.

DLS Data Tables

The average hydrodynamic Radiiof PBTBTz-Br and PBTBTz-SO3Na solution.

PBTz-PyrBr in H2O

Trial 1

Trial 2

Trial 3

PBTz-PyrBr in H2O:MeOH (1:1)

Trial 1

Trial 2

Trial 3

PBTz-PyrBr in MeOH

Trial 1

Trial 2

Trial 3

PBTz-TMABr in H2O

Trial 1

Trial 2

Trial 3

Trial 4

PBTz-TMABr in H2O:MeOH (1:1)

Trial 1

Trial 2

Trial 3

Trial 4

PBTz-TMABr in MeOH

Trial 1

Trial 2

Trial 3

PBTz-Na in Water

Measurement 15

Measurement 16

Measurement 17

Measurement 18

PBTz-Na in 1:1 DMF:H2O

Measurement 12

Measurement 13

Measurement 14

PBTz-PyrBr in 1:1 DMF:H2O

Measurement 9

Measurement 10

Measurement 11

Measurement 12

Measurement 13

PBTz-TMABr in 1:1 DMF:H2O

Measurement 4

Measurement 5

Measurement 6

Measurement 7

1