Molecules 2019, 24, 1742
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2-(4-Diphenylaminophenyl)pyrimidine (1a). The title compound was obtained according to the general
procedure and purified by column chromatography (SiO2, AcOEt/petroleum ether, 3:7). Beige solid.
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Yield: 75% (241 mg). Mp: 173–174 ◦C (lit.: 168–169 ◦C) [50]. H-NMR (300 MHz, CDCl3):
δ 7.17–7.05
(m, 9H), 7.31–7.27 (m, 4H), 8.28 (d, 2H, J = 9.0 Hz), 8.74 (d, 2H, J = 4.8 Hz). 13C-NMR (75 MHz, CDCl3):
δ 118.2, 122.1, 123.6, 125.2, 129.2, 129.4, 130.9, 147.3, 150.3, 157.1, 164.5.
4,6-bis(4-Diphenylaminophenyl)pyrimidine (1b). The title compound was obtained according to the
general procedure and purified by column ch◦romatography (SiO2, AcOEt/petroleum ether, 3:7). Yellow
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solid. Yield: 87% (492 mg). Mp: 230–231 C. H-NMR (300 MHz, CDCl3):
δ
7.17–7.07 (m, 16H),
7.33–7.27 (m, 8H), 7.93 (d, 1H, J = 1.2 Hz), 7.99 (d, 4H, J = 9.0 Hz), 9.17 (d, 1H, J = 1.2 Hz). 13C-NMR
(75 MHz, CDCl3):
δ 110.9, 122.0, 123.9, 125.3, 128.1, 129.5, 129.9, 147.1, 150.4, 159.0, 163.7. HRMS
(ESI/ASAP), m/z calculated for C40H31N4 [M + H]+ 567.2543, found 567.2546.
2,4,6-tris(4-Diphenylaminophenyl)pyrimidine (1c). The title compound was obtained according to the
general procedure and purified by column chromatography (SiO2, AcOEt/petroleum ether, 3:7). Yellow
solid. Yield: 65% (526 mg). Mp: >260 ◦C. 1H-NMR (300 MHz, CDCl3):
δ
7.11–7.06 (m, 6H), 7.18–7.15
(m, 18H), 7.32–7.27 (m, 12H), 7.78 (s, 1H), 8.11 (d, 4H, J = 8.7 Hz), 8.51 (d, 2H, J = 8.7 Hz). 13C-NMR
(75 MHz, CDCl3):
δ 107.9, 122.2, 122.4, 123.3, 123.7, 124.9, 125.2, 128.1, 129.3, 129.4, 130.8, 132.1, 147.2,
147.4, 149.9, 150.2, 163.7, 164.0 HRMS (ESI/ASAP), m/z calculated for C58H44N5 [M + H]+ 810.3591,
found 810.3591.
2-(9-Ethyl-9H-carbazol-3-yl)pyrimidine (2a). The title compound was obtained according to the general
procedure and purified by column chromatography (SiO2, AcOEt/petroleum ether, 3:7). Beige solid.
Yield: 87% (238 mg). Mp: 136–137 ◦C. 1H-NMR (300 MHz, CDCl3):
δ
1.47 (t, 3H, J = 7.2 Hz), 4.41 (q,
6H, J = 7.2 Hz), 7.14 (t, 1H, J = 4.8 Hz), 7.30–7.27 (m, 1H), 7.52–7.42 (m, 3H), 8.22 (d, 1H, J = 7.8 Hz),
8.61 (d, 1H, J = 7.8 Hz), 8.82 (d, 2H, J = 5.1 Hz), 9.22 (s, 2H). 13C-NMR (75 MHz, CDCl3):
13.9, 37.7,
δ
108.4, 108.7, 118.1, 119.5, 120.8, 121.0, 123.3, 123.5, 126.0, 126.2, 128.6, 140.6, 141.8, 157.2, 165.6. HRMS
(ESI/ASAP), m/z calculated for C18H16N3 [M + H]+ 274.1338, found 274.1343.
4,6-bis(9-Ethyl-9H-carbazol-3-yl)pyrimidine (2b). The title compound was obtained according to the
general procedure and purified by column chromatography (SiO2, AcOEt/petroleum ether, 1:1). Pale
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yellow solid. Yield: 76% (352 mg). Mp: 170–171 ◦C (lit.: 176–177 ◦C) [45]. H-NMR (300 MHz, CDCl3):
δ
1.45 (t, 6H, J = 6.9 Hz), 4.33 (q, 4H, J = 6.9 Hz), 7.53–7.30 (m, 8H), 8.32–8.24 (m, 5H), 8.99 (s, 2H), 9.36
(s, 1H). 13C-NMR (75 MHz, CDCl3):
δ
13.8, 37.7, 108.6, 108.8, 111.5, 119.6, 119.7, 120.8, 123.2, 123.5,
124.9, 126.2, 127.9, 140.6, 141.6, 159.0, 164.8.
2,4,6-tris(9-Ethyl-9H-carbazol-3-yl)pyrimidine (2c). The title compound was obtained according to
the general procedure and purified by column chromatography (SiO2, AcOEt/petroleum ether, 3:7)
followed by recrystallization from CH2Cl2/n-heptane. Pale yellow solid. Yield: 51% (330 mg). Mp:
176–177 ◦C. 1H-NMR (300 MHz, CDCl3):
δ
1.52 (t, 9H, J = 6.3 Hz), 4.46 (q, 6H, J = 7.2 Hz), 7.37–7.33 (m,
3H), 7.62–7.47 (m, 9H), 8.22 (d, 1H, J = 2.4 Hz), 8.38–8.33 (m, 3H), 8.59 (2H, d, J = 8.7 Hz), 9.04 (1H, dd,
J1 = 8.7 Hz, J2 = 1.2 Hz), 9.14 (s, 2H), 9.59 (s, 1H). 13C-NMR (75 MHz, CDCl3):
13.9, 37.8, 108.2, 108.7,
δ
108.8, 119.2, 119.4, 119.8, 120.8, 120.9, 121.2, 123.2, 123.4, 123.5, 123.8, 125.4, 125.7, 126.1, 126.8, 129.1,
130.0, 140.6, 141.6. HRMS (ESI/ASAP), m/z calculated for C46H38N5 [M + H]+ 660.3122, found 660.3122.
4. Conclusions
Push-pull pyrimidines substituted with a different number of either triphenylamine or
9-ethylcarbazole groups were prepared by Suzuki cross-coupling reaction from the corresponding
chloropyrimidines and boronic acids. The molecules presented absorption wavelengths in the UV
region and emitted violet-blue light in dichloromethane solution with a higher fluorescence quantum
yield and a stronger ICT observed for the triphenylamine derivatives. The addition of acid was
accompanied by a dramatic quenching of the fluorescence except for the 9-ethylcarbazole derivatives
2b and 2c (and partially for 1b). In these cases, protonation led to the progressive disappearance of the