Y. Li et al. / Journal of Photochemistry and Photobiology A: Chemistry 301 (2015) 14–19
15
Scheme 1. Synthesis of TPE-4DDC.
10 mM, respectively. The different Ag+ solutions were prepared
from AgClO4, AgCF3SO3, AgNO3, AgBF4 and AgOAc in distilled
water, with a concentration of 10 mM, respectively. All UV–vis
absorption and fluorescence spectra were measured in 20 mM 4-
(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer
solution (pH = 7.0) unless otherwise noted. TLC analyses were
performed on silica gel plates and column chromatography was
conducted over silica gel (200–300 mesh).
The melting points were measured on an YRT-3 (Tianjin Xintian
Optical Analytical Instruments Co., Ltd.) melting point apparatus
without calibration.1H and 13C NMR spectra were recorded at 25 ꢂC
on a Bruker 300 MHz or 400 MHz nuclear magnetic resonance
spectrometer. Chemical shifts were reported relative to Me4Si for
1H and 13CNMR spectra. Mass spectra were obtained from DSQ
(Thermo) and LCMS-2010A (Shimadzu). High-resolution mass
spectrometry (HRMS) was performed on MAT95XP (Thermo). FT-
IR spectra were recorded as KBr pellets on an IR-Nicolet Avatrar
330 spectrometer at room temperature. UV–vis absorption spectra
were characterized by a UV-3150 spectrophotometer (Shimadzu)
at room temperature. Fluorescence emission spectra were
investigated by a RF-5301 (Shimadzu) at room temperature.
Quantum yields were measured by a photoluminescence spec-
trometer (FLS-980, Edinburgh Instruments Ltd) at room tempera-
ture.
(15 mL)was addedtothesuspensionof thetitaniumreagentandthe
reaction was refluxed for 10 h at 80 ꢂC. The reaction mixture was
cooled to room temperature and a 10% aqueous K2CO3 solution
(50 mL) was added. The dispersed insoluble material was removed
by vacuum filtration using a celite pad after vigorous stirring for
5 min. The organic layer was separated and the aqueous layer was
extracted with ethyl acetate (3 ꢀ 20 mL). Then the combined
organic phase was dried over Na2SO4 and concentrated in vacuum.
Thecrudeproductwas purifiedbycolumnchromatographyonsilica
gel using petroleum ether (60–90 ꢂC)/EtOAc/CH2Cl2 (v/v/v, 10/1/1)
as eluent. The product was obtained as white powder in a yield of
57.0% (0.88 g). mp = 118.2–120.1 ꢂC. 1H NMR (400 MHz, CDCl3),
d:
6.91 (d, J = 8.8 Hz, 8H), 6.62 (d, J = 8.8 Hz, 8H), 4.01 (t, J = 5.8 Hz, 8H),
3.56 (t, J = 6.4 Hz, 8H), 2.29–2.23 (m, 8H).13C NMR (100 MHz, CDCl3),
d
: 156.84,138.29,136.98,132.48,113.57, 65.05, 32.40, 30.05. MS (EI)
m/z: [M]+ Calcd for C38H40Br4O4: 880; Found: 880. HRMS (EI) m/z:
[M] + Calcd for C38H40Br4O4: 879.9614; Found: 879.9627.
2.2.3. Synthesis of TPE-4DDC
A
mixture of compound 2 (0.41 g, 3.50 mmol), sodium
dimethyldithiocarbamate (0.40 g, 14.00 mmol) and KI (0.14 g,
1.4 mmol) in acetone (15 mL) was refluxed for 20 h under Ar
atmosphere. After the reaction mixture was cooled to room
temperature, the solvent was evaporated under reduced pressure.
The product was purified by column chromatography on silica gel
using petroleum ether (60–90 ꢂC)/EtOAc (v/v, 5/1) as eluent. A
white powder of TPE-4DDC was obtained in a yield of 41% (0.18 g).
2.2. Synthesis
2.2.1. Synthesis of compound 1
mp = 134.4–136.4 ꢂC. 1H NMR (300 MHz, DMSO-d6),
d: 6.82 (d,
A mixture of 4,40-dihydroxybenzophenone (5.00 g, 23.3 mmol),
1,3-dibromopropane (14.20 g, 70.0 mmol) and K2CO3 (9.50 g,
70.0 mmol) in dry DMF (50 mL) was stirred under Ar atmosphere
at room temperature for 24 h. After reaction, the resulting mixture
was extracted with ethyl acetate (3 ꢀ 20 mL). Then the organic
phase was washed with saturated brine (20 mL) and dried over
Na2SO4. After removing solvent under reduced pressure, the crude
product was purified by column chromatography on silica gel using
petroleum ether (60–90 ꢂC) and EtOAc (v/v,10/1) as eluent. A white
powder of compound 1 was obtained in a yield of 26.0% (2.36 g).
J = 8.1 Hz, 8H), 6.67 (d, J = 8.1 Hz, 8H), 3.96–3.92 (m, 8H), 3.44 (s,
12H), 3.33–3.28 (m, 20H), 2.05–2.01 (m, 8H). 13C NMR (75 MHz,
DMSO-d6), d: 194.80, 156.45, 137.82, 136.15, 131.81, 113.60, 65.94,
44.85, 41.24, 33.35, 28.13. IR (cmꢁ1): 3428.51, 2921.74, 1605.09,
1506.30, 1374.29, 1290.23, 1242.17, 1172.56, 1143.28, 1038.79,
983.32. MS (ESI) m/z: [M + H]+ Calcd for C50H65N4O4S8: 1041.2;
Found: 1041.0. HRMS (ESI) m/z: [M + H]+ Calcd for C50H65N4O4S8:
1041.27660; Found: 1041.27691.
3. Results and discussion
mp = 62.4–63.7 ꢂC; 1H NMR (300 MHz, CDCl3),
4H), 6.94 (d, J = 8.7 Hz, 4H), 4.18 (t, J = 5.8 Hz, 4H), 3.61 (t, J = 6.3 Hz,
d: 7.76 (d, J = 8.7 Hz,
3.1. AIE studies
4H), 2.39–2.31 (m, 4H). 13C NMR (75 MHz, CDCl3),
d: 194.74, 161.73,
132.06, 130.79, 113.87, 65.52, 32.23, 29.74. MS (ESI) m/z: [M + Na] +
The AIE properties of TPE-4DDC were examined by studying the
fluorescence behavior of its diluted solution in H2O/THF under
different H2O fractions (Fig.1). TPE-4DDC has four phenyl rings with
intramolecular rotations that quench its emission, however, when it
turns into an aggregated form, the intramolecular coordinations
occur. Accordingly, the intramolecular rotations are restricted and
thenon-radiativedecaychannelsarehindered.Asaresult,TPE-4DDC
Calcd for C19H20Br2O3Na: 479.0; Found: 478.7.
2.2.2. Synthesis of compound 2
A suspension of TiCl4 (0.78 mL, 7.0 mmol) and Zn powder (0.92 g,
14.0 mmol) in 35 mL of dry THF was refluxed under Ar atmosphere
for 2 h. A solution of compound 1 (1.60 g, 3.50 mmol) in dry THF