1594, 1494, 1450 cmꢃ1. HRMS (EI+) Found (M+): 448.0576,
Calc. for C27H17BrN2: 448.0575.
Me4Si) 2.57 (s, 6H), 7.16–7.79 (m, 26H), 8.72 (d, J ¼ 8.0 Hz, 2H),
8.78 (d, J ¼ 8.4 Hz, 2H), 8.88 (d, J ¼ 7.9 Hz, 2H). IR (KBr): 3055,
2915, 1605, 1513, 1450, 1376 cmꢃ1. HRMS (FAB+) Found (MH+)
767.3177, Calc. for C56H38N4: 766.3096. Anal. Found: C, 87.71;
H, 5.01; N, 7.34. Calc. for C56H38N4: C, 87.70; H, 4.99; N, 7.31%.
2-(4-Bromophenyl)-1-p-tolyl-1H-phenanthro[9,10-d]imidazole
ꢀ
(1b). Yield: 3.91 g, (88%). mp ¼ 236 C. dH(200 MHz; CDCl3;
Me4Si) 2.53 (s, 3H), 7.17–7.27 (m, 2H), 7.30–7.53 (m, 9H), 7.58–
7.67 (m, 1H), 7.73 (td, J ¼ 7.9, J ¼ 1.0 Hz, 1H), 8.68 (d, J ¼ 8.1
Hz, 1H), 8.74 (d, J ¼ 8.4 Hz, 1H), 8.83 (d, J ¼ 7.5 Hz, 1H); dC(50
MHz; CDCl3; Me4Si) 21.5 (q), 120.8 (d), 122.6 (d), 122.9 (s),
123.1 (d), 123.2 (s), 124.0 (d), 124.9 (d), 125.6 (d), 126.2 (d), 127.1
(s), 127.3 (d), 128.2 (s), 128.3 (s), 128.60 (d), 129.3 (s), 129.5 (s),
130.7 (d), 130.9 (d), 131.4 (d), 135.8 (s), 137.3 (s), 140.1 (s), 149.7
(s). IR (KBr): 3047, 2966, 1609, 1513, 1450, 1373 cmꢃ1. HRMS
(EI+) Found (M+): 462.0729, Calc. for C28H19BrN2: 462.0732
4,40-Bis(1-p-anisyl-1H-phenanthro[9,10-d]imidazole-2-yl)biphenyl
(2c). Yield: 1.33g, (75%). mp ¼ 403 ꢀC. dH(200 MHz; CDCl3;
Me4Si) 3.98 (s, 6H), 6.73–7.79 (m, 26H), 8.72 (d, J ¼ 8.3 Hz, 2H),
8.78 (d, J ¼ 8.2 Hz, 2H), 8.88 (d, J ¼ 8.3 Hz, 2H). IR (KBr): 3062,
2959, 1601, 1509, 1458, 1249, 1031 cmꢃ1. HRMS (FAB+) Found
(MH+) 799.3073, Calc. for C56H38N4O2: 798.2995. Anal. Found:
C, 84.18; H, 4.74; N, 7.03, Calc for C56H38N4O2: C, 84.19; H,
4.79; N, 7.01%.
2-(4-Bromophenyl)-1-(4-methoxyphenyl)-1H-phenanthro[9,10-
d]imidazole (1c). Yield: 3.68 g, (80%). mp ¼ 239 ꢀC. dH(200 MHz;
CDCl3; Me4Si) 3.95 (s, 3H), 7.09 (d, J ¼ 8.7 Hz, 2H), 7.22–7.34
(m, 1H), 7.39 (d, J ¼ 8.7 Hz, 2H), 7.44–7.56 (m, 6H), 7.61–7.68
(m, 1H), 7.74 (td, J ¼ 8.0, J ¼ 1.1 Hz, 1H), 8.70 (d, J ¼ 7.9 Hz,
1H), 8.76 (d, J ¼ 8.4 Hz, 1H), 8.83 (d, J ¼ 8.0 Hz, 1H); dC(50
MHz; CDCl3; Me4Si) 55.6 (q), 115.3 (d), 120.8 (d), 122.6 (d),
123.0 (s), 123.1 (d), 123.3 (s), 124.1 (d), 125.0 (d), 125.6 (d), 126.3
(d), 127.1 (s), 127.3 (d), 128.2 (s), 128.4 (s), 129.3 (s), 129.5 (s),
130.1 (d), 130.8 (d), 130.9 (s), 131.4 (d), 137.3 (s), 149.9 (s), 160.4
3. Results and discussion
3.1 Physical properties of bis(phenanthroimidazolyl)biphenyl
derivatives 2
As shown in Scheme 1, the key intermediates, 2-(4-bromo-
phenyl)-1-aryl-1H-phenanthro[9,10-d]imidazole derivatives 1a–
1c, can be easily prepared from commercially available starting
materials through a simple one-step reaction in high yields
(80–90%). The desired products 2a–2c were prepared in good
yields from the homo-coupling reaction of 1a–1c at 80 ꢀC for 24
h using NiCl2/PPh3 as the catalyst and Zn powder as the
reducing agent. It is noteworthy that our syntheses are per-
formed under mild reaction conditions in the presence of inex-
pensive metal catalysts; in addition, the overall yields for all
these products are more than 60% without column chroma-
tography purification. Therefore, the preparations of the pre-
sented bis(phenanthroimidazolyl)biphenyl derivatives are
promising for large-scale production. Products 2 were fully
(s). IR (KBr): 3055, 2959, 1609, 1513, 1450, 1251, 1030 cmꢃ1
.
HRMS (EI+) Found (M+): 478.0681, Calc. for C28H19BrN2O
478.0681
Synthesis of bis(phenanthroimidazolyl)biphenyl derivatives
2a–2c
A round-bottom flask containing compound 1a (2.0 g, 4.45
mmol), NiCl2 (0.058 g, 0.45 mmol), Zn powder (0.29 g, 4.45
mmol), KI (1.11 g, 6.68 mmol) and PPh3 (0.47 g, 1.78 mmol) was
purged with nitrogen three times, 20 mL of DMF was added to
the flask and the mixture was stirred at 80 ꢀC for 24 h under
nitrogen. The Zn and inorganic salts were then removed by
filtration of the hot reaction mixture and the residue was washed
with DMF. After evaporation of the filtrate under vacuum, the
residue was collected and washed with methanol and then dried
in vacuum to give product 2a (1.35 g, 82%). The product was
further purified by vacuum sublimation technique at 330 ꢀC and
3–5 ꢂ 10ꢃ3 Pa. The other derivatives 2b and 2c were prepared
according to a similar procedure from compounds 1b and 1c,
respectively. The synthetic route to for bis(phenan-
throimidazolyl)biphenyl derivatives is shown in Scheme 1.The
yields and important spectral data are given below.
1
characterized by their H and 13C NMR, high resolution mass
data and elemental analysis. As shown in Fig. 1, the structure of
2a (PPIP) was further confirmed by single-crystal X-ray
diffraction. The central biphenyl group of PPIP adopts
a coplanar configuration, and the inter-ring torsion angles
between the biphenyl group and the two phenanthroimidazolyl
groups are ca. 30ꢀ. In addition, the phenyl substituents are
highly twisted about the phenanthroimidazolyl rings with
dihedral angles of about 85ꢀ.
The thermal properties of the materials were examined by
differential scanning calorimetry (DSC). Owing to the rigid and
4,40-Bis(1-phenyl-1H-phenanthro[9,10-d]imidazole-2-yl)biphenyl
ꢀ
(2a). Yield: 1.35 g, (82%). mp ¼ 402 C. dH(200 MHz; CDCl3;
Me4Si) 6.73–7.79 (m, 28H), 8.72 (d, J ¼ 8.0 Hz, 2H), 8.79 (d, J ¼
8.4 Hz, 2H), 8.89 (d, J ¼ 7.9 Hz, 2H). IR (KBr): 3055, 1595, 1494,
1451 cmꢃ1. HRMS (FAB+) Found (MH+) 739.2861. Calc. for
C54H34N4 738.2783. Anal. Found: C, 87.67; H, 4.68; N, 7.52.
Calc. for C54H34N4: C, 87.78; H, 4.64; N, 7.58%.
4,40-Bis(1-p-tolyl-1H-phenanthro[9,10-d]imidazole-2-yl)biphenyl
(2b). Yield: 1.37g, (80%). mp ¼ 405 ꢀC. dH(200 MHz; CDCl3;
Fig. 1 X-ray structure of PPIP.
This journal is ª The Royal Society of Chemistry 2009
J. Mater. Chem., 2009, 19, 1865–1871 | 1867