3.6. Synthesis (See the Reaction Scheme in the Supporting Information for the Corresponding Numbering of the Compounds)
N4,
N4,
N4′,
N4′-Tetraphenylbiphenyl-4,4′-diamine (
3) [
62,
63]. To a solution of
N4,
N4′-diphenylbiphenyl-4,4′-diamine (1 g, 3 mmol) and iodobenzene (2.4 g, 11.8 mmol) in anhydrous toluene (30 mL) were added 1,10-phenantroline (107 mg, 0.6 mmol), copper(I) chloride (60 mg, 0.6 mmol) and potassium hydroxide (1.3 g, 23.2 mmol). The solution was stirred at 120 °C for 48 h. It was then cooled to room temperature; afterwards, water (50 mL) was slowly added. The organic phase was extracted with dichloromethane (3 × 30 mL). The combined organic fractions were dried over MgSO
4, filtered, and the solvent was evaporated. The crude product was purified by column chromatography (SiO
2, dichloromethane/hexane 1:9
v/
v) to afford the product as a white solid (1.23 g, 85%).
1H NMR (400 MHz, CDCl
3): δ 7.47 (d,
J = 8.7 Hz, 4H), 7.29 (t,
J = 7.4 Hz, 8H), 7.19-7.11 (m, 12H), 7.05 (t,
J = 7.3 Hz, 4H) ppm.
13C NMR (100 MHz, CDCl
3): δ 147.9, 146.9, 134.9, 129.4, 127.4, 124.4, 124.2, 122.9 ppm. HRMS m/z = [M+H]
+ calcd. for C
36H
29N
2 489.2325; found 489.2325.
4,4′-(Biphenyl-4,4′-diylbis(phenylazanediyl))dibenzaldehyde (
4) [
6,
62]. A solution of
3 (0.7 g, 1.4 mmol) in anhydrous 1,2-dichloroethane (10 mL) and
N,
N-dimethylformamide (2.76 mL) was cooled to 0 °C. Slowly, POCl
3 (3.45 mL) was added. Afterwards, the mixture was slowly warmed to room temperature. The mixture was then heated at 100 °C for 15 h, and then it was cooled to room temperature, neutralized with saturated NaHCO
3 and extracted with dichloromethane (3 × 20 mL). The combined organic layer was dried over MgSO
4 and the solvent was evaporated. The product was isolated as a yellow solid (650 mg, 81%) after purification by column chromatography (SiO
2, CH
2Cl
2/hexane 8:2
v/
v).
1H NMR (400 MHz, CDCl
3) δ 9.83 (s, 2H), 7.71 (d,
J = 8.9 Hz, 4H), 7.55 (d,
J = 8.8 Hz, 4H), 7.40-7.32 (m, 4H), 7.26-7.16 (m, 10H), 7.08 (d,
J = 8.7 Hz, 4H) ppm.
13C NMR (100 MHz, CDCl
3) δ 190.6, 153.3, 146.2, 145.6, 136.8, 131.5, 130.0, 129.5, 128.1, 126.5, 126.3, 125.4, 119.9 ppm. HRMS m/z = [M+H]
+ calcd. For C
38H
29N
2O
2 545.2224, found 545.2207.
(([1,1′-Biphenyl]-4,4′-diylbis(phenylazanediyl))bis(4,1-phenylene))dimethanol (5). A solution of 4 (0.45 g, 0.82 mmol) in anhydrous THF (20 mL) was cooled to 0 °C. Under a nitrogen atmosphere, NaBH4 (0.12 g, 3.3 mmol) was added portion-wise. The solution was slowly warmed to room temperature and it was stirred for 24 h. Water (30 mL) was slowly added to the mixture; afterwards, the organic phase was extracted with dichloromethane (3 × 30 mL). The organic layer was dried over MgSO4, filtered and the solvent was evaporated. The crude product was purified by column chromatography (SiO2, dichloromethane) to afford the product as a white solid (390 mg, 86%). 1H NMR (400 MHz, CDCl3): δ 7.45 (d, J = 8.7 Hz, 4H), 7.31-7.24 (m, 8H), 7.13 (d, J = 8.3 Hz, 12H), 7.04 (t, J = 7.3 Hz, 2H), 4.66 (s, 4H) ppm. 13C NMR (100 MHz, CDCl3): δ 147.7, 147.5, 146.8, 135.3, 135.0, 129.4, 128.4, 127.5, 124.5, 124.3, 124.3, 123.1, 65.2 ppm. HRMS m/z = [M+H]+ calcd. for C38H33N2O2 549.2537; found 549.2536.
N4,N4′-Diphenyl-N4,N4′-bis(4-(((4-vinylbenzyl)oxy)methyl)phenyl)-[1,1′-biphenyl]-4,4′-diamine (1). A solution of 5 (0.2 mg, 0.36 mmol) in anhydrous DMF (5 mL) was cooled to 0 °C. To this was added sodium hydride (60% in mineral oil; 60 mg, 1.46 mmol). The mixture was stirred at 0 °C for 30 min and 1-(chloromethyl)-4-vinylbenzene (0.17 g, 1.1 mmol) was then added dropwise. The solution was stirred at room temperature for 24 h. Afterwards, water (30 mL) and dichloromethane (30 mL) were added to the mixture. The organic phase was extracted with dichloromethane (3 × 30 mL), dried over MgSO4 and then filtered. The solvent was evaporated and the crude product was purified by column chromatography (SiO2, dichloromethane/hexane 6:4 v/v) to afford the title compound as a white solid (250 mg, 88%). 1H NMR (400 MHz, CDCl3): δ 7.49 (d, J = 8.6 Hz, 4H), 7.46 (d, J = 8.2 Hz, 4H), 7.40 (d, J = 8.2 Hz, 4H), 7.30 (m, 8H), 7.19-7.15 (m, 12H), 7.07 (t, J = 7.3 Hz, 2H), 6.77 (dd, J = 17.6, 10.9 Hz, 2H), 5.81 (dd, J = 17.6, 0.8 Hz, 2H), 5.29 (dd, J = 10.9, 0.8 Hz, 2H), 4.63 (s, 4H), 4.54 (s, 4H) ppm. 13C NMR (100 MHz, CDCl3): δ 147.7, 147.3, 146.7, 138.0, 137.1, 136.6, 134.9, 132.6, 129.4, 129.2, 128.1, 127.4, 126.4, 124.4, 124.2, 123.0, 113.9, 72.0, 71.9 ppm. HRMS m/z = [M+H]+ calcd. for C56H49N2O2 781.3789, found 781.3763.
1,1′-Bis(4-vinylbenzyl)-4,4′-bipyridine-1,1′-diium hexafluorophosphate(V) (
2) [
64]. A solution of 4,4′-bipyridine (0.25 g, 1.6 mmol) and 1-(chloromethyl)-4-vinylbenzene (0.97 g, 6.4 mmol) in acetonitrile (3 mL) was placed in a microwaveable pressure tube after degassing with nitrogen. It was sealed and then heated at 135 °C for 10 min in a microwave reactor. The yellow solid was filtered, solubilized in water and a solution of NH
4PF
6 (2.61 g, 16.0 mmol) was then added. The mixture was stirred for 30 min, and the resulting solid was filtered. The title compound was obtained as a slightly pink solid (960 mg, 88%) after recrystallizing from water.
1H NMR (400 MHz, MeOD): δ 9.36 (d,
J = 7.0 Hz, 4H), 8.70 (d,
J = 6.8 Hz, 4H), 7.59 (s, 8H), 6.79 (dd,
J = 17.6, 10.9 Hz, 2H), 5.99 (s, 4H), 5.88 (dd,
J = 17.6, 0.6 Hz, 2H), 5.35 (dd,
J = 11.0, 0.5 Hz, 2H) ppm.
13C NMR (100 MHz, MeOD): δ 151.6, 147.0, 140.9, 137.0, 133.5, 130.7, 128.6, 128.4, 116.1, 65.6 ppm. HRMS m/z = [M-PF
6]
+ calcd. for C
28H
26N
2(PF
6)
2 535.1723; found 535.1722.