90
Y. Wang et al. / Dyes and Pigments 100 (2014) 87e96
cooling to room temperature, the mixture was poured into water
(150 mL), then extracted with CH2Cl2, washed with brine, dried
under anhydrous magnesium sulfate. After the removal of solvent
in vacuo, the crude product was purified by column chromatog-
raphy over silica using petroleum ether/dichloromethane as eluent
to afford yellow solid. Yield: 70.3%, m.p.: 294 ꢁC. 1H NMR (400 MHz,
3. Results and discussion
3.1. Synthesis and characterization
The synthetic route to the target molecules are outlined in
Scheme 1. It is noteworthy that through condensation of 4-bromo-
1,8-naphthalic anhydride with 4-tert-butylbenzene-1,2-diamine,
according to the 1H NMR characterization result, an isomeric
mixture of 6ae6d could be prepared. Yet despite of our enormous
efforts on separation, we fail to isolate them through either
recrystallization or column chromatography due to their quite
similar polarity, and the mixture exhibits only one spot on TLC in a
large variety of eluents. This is consistent with the literature report
[50]. Nevertheless, by MizorokieHeck cross-coupling of the
mixture of 6ae6d with 8, the isomeric mixture of target molecules
FNIaeFNId are found to show slightly different polarity. Through
precise control on the proportion of toluene/ethyl acetate, FNIa and
FNIb have been isolated via gradient column chromatography
successfully, whereas the isolation of FNIc and FNId seems to be
improbable by column chromatography, since they could not even
be separated through high performance liquid chromatography
(HPLC) technique (vide ESI). Consequently, only the photophysical
properties of FNIa and FNIb have been investigated in detail.
To provide more solid evidence for the molecular structure of
FNIa and FNIb, two-dimensional NMR (COSY, HMQC and HMBC)
spectra of the two compounds have been recorded. As the 13C NMR
signal of carbonyl-carbon atom should exhibit more downfield-
shift effect than that of the imino-carbon atom [51,52], the signals
at w160 ppm and w149 ppm should be assigned to the carbon
atoms of carbonyl and imino groups, respectively. Therefore,
through the HMBC correlations between corresponding carbon and
hydrogen atoms, the molecular structures of FNIa and FNIb have
been determined (illustrated in Scheme 1). All the NMR spectra of
FNIa and FNIb have been shown in the Supporting Information.
CDCl3),
d
(ppm): 8.73 (d, J ¼ 7.2 Hz, 1H), 8.69 (d, J ¼ 6.8 Hz, 1H), 8.48
(d, J ¼ 9.6 Hz, 1H), 8.30 (s, 1H), 8.19 (d, J ¼ 7.6 Hz, 1H), 7.87 (d,
J ¼ 7.6 Hz, 1H), 7. 75e7.71 (t, J ¼ 8.4 Hz, J ¼ 7.6 Hz, 1H), 7.67 (d,
J ¼ 8.4 Hz, 2H), 7.61e7.45 (m, 8H), 7.35e7.27 (m, 3H), 1.45 (s, 9H),
1.39 (s, 9H). 13C NMR (100 MHz, CDCl3),
d (ppm): 164.9, 164.7, 151.5,
151.0, 148.4, 141.8, 141.1. 134.7, 133.6, 132.8, 131.7, 131.4, 130.8, 130.4,
129.4, 128.5, 128.1, 128.00, 127.1, 126.9, 126.7, 126.7, 126.6, 123.7,
123.2, 123.1, 121.9, 121.5, 120.6, 120.4, 110.4, 110.3, 35.0, 34.9, 31.6,
31.5. FT-IR (KBr, cmꢀ1): 3052 (Ar, C]H), 2961 (ꢀCH3), 1701 (C]O),
1262 (ArN). TOF-MS: m/z Found 649.2832 (M þ Naþ), and Calc. for
C
44H38N2O2 for (Mw þ Naþ): 649.2831.
2.3.4. Synthesis of 11-tert-butyl-((E)-3-(2-(7-(diphenylamino)-9,9-
diethyl-9H-fluoren-2-yl)vinyl)-7H-benzimidazo[2,1-a]benzo[de]
isoquinolin-7-one (FNIa) and 11-tert-butyl-((E)-4-(2-(7-
(diphenylamino)-9,9-diethyl-9H-fluoren-2-yl)vinyl)-7H-
benzimidazo[2,1-a]benzo[de]isoquinolin-7-one (FNIb)
A flask was charged with a mixture of 6 (0.94 g, 2.16 mmol), 8
(1.07 g, 2.59 mmol), Pd(OAc)2 (1.0 mg, 0.043 mmol), P(o-tolyl)3
(0.026 g, 0.086 mmol), triethylamine (1.53 g, 15.12 mmol) and DMF
(30 mL). The reaction mixture was heated at 90 ꢁC for 24 h under
N2. After cooled to room temperature, the mixture was poured into
water (200 mL), and the red solid was collected, washed with water
and dried in vacuo. The crude product was purified by column
chromatograph over silica using toluene/ethyl acetate as eluent to
afford pure product FNIa as dark-red solid, and FNIb as orange-red
solid.
11-tert-butyl-((E)-3-(2-(7-(diphenylamino)-9,9-diethyl-9H-flu-
oren-2-yl)vinyl)-7H-benzimidazo[2,1-a]benzo[de]isoquinolin-7-
one (FNIa). Yield: 17.0%, m.p. 311 ꢁC. 1H NMR (400 MHz, CDCl3),
3.2. Spectroscopic properties
d
(ppm): 8.71 (d, J ¼ 7.6 Hz, 2H), 8.62 (d, J ¼ 8.0 Hz, 1H), 8.38 (d,
J ¼ 8.4 Hz, 1H), 7.96 (d, J ¼ 7.6 Hz, 1H), 7.89e7.88 (m, 3H), 7.76 (t,
J ¼ 8.0 Hz,1H), 7.66 (d, J ¼ 8.0 Hz,1H), 7.59 (d, J ¼ 8.4 Hz, 2H), 7.55 (s,
1H), 7.52e7.50 (dd, J ¼ 8.4 Hz, J ¼ 1.6 Hz, 1H), 7.36 (d, J ¼ 16 Hz, 1H),
7.29e7.25 (m, 5H), 7.14 (d, J ¼ 8.0 Hz, 5H), 7.07e7.01(m, 3H), 2.08e
1.93 (m, 4H), 1.45 (s, 9H), 0.42 (t, J ¼ 7.2 Hz, 6H). 13C NMR (100 MHz,
3.2.1. UVevis absorption and PL emission properties of FNIa and
FNIb
In dilute dichloromethane solution (10ꢀ5
M
ꢀ1), the lab of FNIa
and FNIb are located at 477 nm and 468 nm, respectively (shown in
Fig. 1). The w10 nm bathochromic-shifted lab of FNIa relative to
FNIb suggests that FNIa has more extended conjugation system.
Under excitation at 400 nm, FNIa and FNIb emit red fluorescence
with lEMmax of 652 nm and 664 nm, respectively (data summarized
in Table 1). It is noteworthy that both FNIa and FNIb show obvious
CDCl3),
d (ppm): 160.5, 151.7, 150.6, 149.4, 149.3, 147.9, 147.6, 144.0,
142.3, 139.5,135.9, 135.3, 134.9,131.5, 131.1, 130.1, 129.5,129.2,127.4,
126.9, 126.4, 124.2, 124.0, 123.5, 123.4, 123.1, 122.6, 122.2, 121.3,
120.6, 119.4, 119.2, 119.1, 116.3, 115.0, 56.1, 35.1, 32.7, 31.7, 8.6. FT-IR
(KBr, cmꢀ1): 3034 (Ar, C]H), 2960 (-CH3), 2853 (-CH2), 1693 (C]
O), 1602 (C]N),1314 (ArN). TOF-MS: m/z Found 740.3614 (M þ Hþ),
and Calc. for C53H45N3O for (Mw þ Hþ): 740.3641.
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
absorption
FNIa
11-tert-butyl-((E)-4-(2-(7-(diphenylamino)-9,9-diethyl-9H-flu-
oren-2-yl)vinyl)-7H-benzimidazo[2,1-a]benzo[de]isoquinolin-7-
one (FNIb). Yield: 15.2%, m.p.: 291 ꢁC. 1H NMR (400 MHz, CDCl3),
FNIb
emission
FNIa
d
(ppm): 8.62 (d, J ¼ 7.2 Hz, 1H), 8.56 (d, J ¼ 8.0 Hz, 1H), 8.54 (d,
FNIb
J ¼ 1.6 Hz, 1H), 8.34 (d, J ¼ 8.4 Hz, 1H), 7.83 (d, J ¼ 8.0 Hz, 1H), 7.74e
7.70 (m, 2H), 7.67e7.63 (m, 2H), 7.59 (d, J ¼ 8.4 Hz, 1H), 7.56e7.53
(m, 2H), 7.49e7.47 (dd, J ¼ 8.4 Hz, J ¼ 1.6 Hz, 1H), 7.29e7.25 (m, 5H),
7.16e7.13 (m, 5H), 7.07e7.01 (m, 3H), 2.09e1.94 (m, 4H), 1.45 (s,
9H), 0.44 (t, J ¼ 7.2 Hz, 6H). 13C NMR (100 MHz, CDCl3),
d (ppm):
160.4, 151.7, 150.6, 149.0, 149.0, 147.9, 147.7, 142.7, 142.5, 141.6, 136.1,
135.8,134.6,131.9,131.1,129.8,129.2,127.4,127.3, 126.7,126.6,124.0,
123.4, 122.7, 122.0, 121.3, 120.8, 120.7, 119.4, 119.0, 112.5, 56.1, 35.3,
32.7, 31.8, 8.6. FT-IR (KBr, cmꢀ1): 3035 (Ar, C]H), 2959 (-CH3), 2869
(-CH2), 1693 (C]O), 1618 (C]N), 1364 (ArN). TOF-MS: m/z Found
740.3616 (M þ Hþ), and Calc. for C53H45N3O for (Mw þ Hþ):
740.3641.
350 400 450 500 550 600 650 700 750 800 850 900
Wavelength (nm)
Fig. 1. Normalized absorption and fluorescence spectra of FNIa and FNIb in
dichloromethane solution.