142
B. Huang et al. / Dyes and Pigments 117 (2015) 141e148
and 3b, we present a detailed study of photophysical characteristics
including fluorescence solvatochromical effects, time-resolved fluo-
rescence and phosphorescence, delayed fluorescence lifetime, and
timeedependent density functional theory (TDeDFT). To reveal the
importance of molecular configuration for giving effective TADF,
Nephenylcarbazole and triphenylamine substituted benzonitriles
(2a, 2b) as the corresponding monomers of 3a and 3b have been
prepared for comparison in this paper.
2.2. Synthesis
2.2.1. Synthesis of 3e((9ephenyl)carbazole3eyl)ebenzonitrile
(2a)
To a solution of 3ebromobenzonitrile (0.546 g, 3.0 mmol) and
Nephenyle3e(4,4,5,5e tetramethyle1,3,2edioxaborolanee2eyl)e
6Hecarbazole (1a, 1.107 g, 3.0 mmol) in toluene (20 mL) and ethanol
(4 mL) was added aqueous K2CO3 solution (2.0 M, 2 mL). The reaction
mixture was then purged with nitrogen for 10 min before adding
tetrakis(triphenylphosphine)palladium(0) (0.055 g, 0.048 mmol).
The reaction mixture was heated under reflux for 24 h under ni-
trogen. The resulting mixture was cooled to room temperature and
then poured into water and extracted with CH2Cl2 (3 ꢁ 20 mL). The
combined organic phase was washed with saturated aqueous NaCl
solution (2 ꢁ 10 mL) and dried with anhydrous Na2SO4. After
removal of the solvent by rotary evaporation, the residue was puri-
fied by silica gel column chromatography to afford 2a as a white
solid. Yield: 73.6%. Mp: 117e119 ꢂC. IR (KBr, cmꢀ1):3057, 2225, 1626,
1597, 1501, 1472, 1455, 1402, 1361, 1232. 1H NMR (300 MHz, CDCl3)
2. Experimental
2.1. General
DFT calculations of these compounds were performed using the
Gaussian 09 program package [33]. The calculations were opti-
mized at the B3LYP/6e31G(d) level of theory. The molecular or-
bitals were visualized using Gaussview. To investigate the
properties of the excited states of these compounds, we performed
quantum chemical calculations of the lowelying excited states of
these compounds using TDeDFT. The ten lowest singlet and triplet
excited states were calculated by the TDeDFT method at their
optimized groundestate geometries using the same functional and
basis set [12].
d
(ppm): 8.35 (s, 1H), 8.24e8.21 (d, J ¼ 7.5 Hz, 1H), 8.02 (s, 1H),
7.98e7.93 (d, J ¼ 7.5 Hz, 1H), 7.69e7.36 (m, 12H). 13C NMR (75 MHz,
CDCl3) d(ppm):110.46, 110.74, 113.25, 119.24, 119.48, 120.75, 120.79,
123.57, 124.44, 125.44, 126.88, 127.39, 128.10, 129.92, 130.25, 130.37,
131.06, 131.22, 131.91, 137.73, 141.19, 141.82, 143.50. Anal. Calcd. for
All materials and reagents were purchased from commercial
sources and used without further purification. IR spectra were
recorded on a 5DX-FT-2 spectrophotometer using KBr pellets. 1H
NMR and 13C NMR spectra were recorded on a Bruker ARX300 NMR
spectrometer at room temperature. Elemental analyses were per-
formed on an Elementar Vario EL CHN elemental analyzer. UVevis
absorption spectra and fluorescence spectra were recorded on a
spectrophotometer (Agilent 8453) and a fluorospectrophotometer
(Jobin Yvon, Fluoromaxe3), respectively. The transient photo-
luminescence decay characteristics and time-resolved fluorescence
were recorded using a spectrofluorometer (Floromax-4, Horiba).
The fast decay component was recorded with a 350 nm LED exci-
tation source, while the slow decay component was recorded with
a flash lamp source. Cyclic voltammetry (CV) measurements was
carried out on a Princeton Applied Research potentiostat/galvano-
stat model 283 voltammetric analyzer in CH2Cl2 solutions (10ꢀ3 M)
at a scan rate of 100 mV sꢀ1 with a conventional threeeelectrode
configuration consisting of platinum plate working electrode, a
silver wire pseudoereference electrode, and a platinum wire
counter electrode. The supporting electrolyte was tetrabuty-
lammonium hexafluorophosphate (TBAPF6, 0.1 M) and ferrocene
was selected as the internal standard. The solutions were bubbled
with a constant nitrogen flow for 10 min before measurements.
C
25H16N2 (%): C, 87.18; H, 4.68; N, 8.13. Found: C, 87.28; H, 4.72; N,
8.19. MS (MALDI-TOF) [m/z]:Calcd for C25H16N2, 344.41; found,
344.3834.
2.2.2. Synthesis of N,Nediphenyle(1,10ebiphenyl)e30ecyano-
4eamine (2b)
A procedure similar to that used for 2a was followed but with
N,Nediphenyle4e(4,4,5,5etetramethyle1,3,2edioxaborolane2e-
yl)aniline (1b) instead of 1a. Yield: 62.5%. Mp: 122e124 ꢂC. IR (KBr,
cmꢀ1): 3005, 2229,1588, 1514, 1482, 1432, 1401, 1330, 1276. 1H NMR
(300 MHz, CDCl3)
7.59e7.48 (m, 2H), 7.44e7.41 (d, J ¼ 8.7 Hz, 2H), 7.32e7.26 (m, 4H),
7.16e7.04 (m, 8H). 13C NMR (75 MHz, CDCl3)
(ppm):113.29, 119.33,
123.26, 123.70, 123.85, 124.75, 125.19, 128.11, 129.45, 129.82, 129.96,
130.45, 130.37, 131.21, 132.45, 142.25, 147.73, 148.66. Anal. Calcd. for
d(ppm): 7.83 (s, 1H), 7.79e7.77 (d, J ¼ 7.8 Hz, 1H),
d
C25H18N2 (%): C, 86.68; H, 5.24; N, 8.09. Found: C, 86.74; H, 5.22; N,
8.13. MS (MALDI-TOF)[m/z]:Calcd for C25H18N2, 346.42; found,
346.2814.
2.2.3. Synthesis of 30,3000,3000''e(1,3,5etriazinee2,4,6etriyl)
tris(N,Nediphenyle(1,10ebiphenyl)e4eamine) (3b)
To a solution of 2,4,6etris(3ebromophenyl)triazine (1c, 0.546 g,
1.0 mmol) and 1b (1.113 g, 3.0 mmol) in toluene (20 mL) and
ethanol (4 mL) was added 2 mL of 2.0 M aqueous Na2CO3 solution.
The reaction mixture was then purged with nitrogen for ten mi-
nutes before adding tetrakis(triphenylphosphine)palladium(0)
(0.055 g, 0.048 mmol). The reaction mixture was heated under
reflux for 24 h under nitrogen. The resulting mixture was cooled to
room temperature and then poured into water and extracted with
CH2Cl2 (3 ꢁ 20 mL). The combined organic phase was washed with
saturated aqueous NaCl solution (2 ꢁ 10 mL) and dried with
anhydrous Na2SO4. After removal of the solvent by rotary evapo-
ration, the residue was purified by silica gel column chromatog-
raphy to afford 3b as a yellow solid. Yield: 42.4%. Mp: 209e211 ꢂC.
IR (KBr, cmꢀ1): 3060, 3032, 1591, 1527, 1510, 1492, 1436, 1406, 1358,
2.1.1. X-ray crystallography
X-ray crystallographic analysis of 2b was performed on a Nonius
CAD-4 single-crystal diffractometer by using MoKa radiation
(l
¼ 0.71073 Å) with an
u/2q scan mode at 293 K. The structure was
solved by direct methods and refined by full-matrix least-squares
procedures on F2 using SHELXL-97 program. All non-hydrogen
atoms were refined anisotropically, and the hydrogen atoms were
introduced at calculated positions. The isotropic temperature fac-
tors were fixed to 1.2 times (1.5 times for CH3 groups) the equiva-
lent isotropic displacement parameters of the C-atom which the H-
atom was attached to. Drawings were produced using Diamond 3.0
and Mercury 1.4.1 software. Crystallographic data for the structure
in this paper has been deposited with the Cambridge Crystallo-
graphic Data Centre as supplemental publications.
1328, 1276. 1H NMR(300 MHz, CDCl3)
d(ppm): 9.00 (s, 3H),
8.77e8.74 (d, J ¼ 7.5 Hz, 3H), 7.86e7.83 (d, J ¼ 7.5 Hz, 3H), 7.67e7.64
(d, J ¼ 8.1 Hz, 9H), 7.31e7.06 (m, 36H). 13C NMR (75 MHz, CDCl3)
CCDC 994818 for 2b. The data can be obtained free of charge
from the Cambridge Crystallographic Data Centre via www.ccdc.
d(ppm):123.44, 124.33, 124.88, 127.42, 127.92, 128.34, 129.48,
129.73, 131.12, 134.96, 137.12, 141.40, 147.90, 148.05, 172.03. Anal.
Calcd. for C75H54N6 (%): C, 86.68; H, 5.24; N, 8.09. Found: C, 86.74;