S. Fukuzumi, F. DꢀSouza et al.
Procedure for synthesis of Fc2–azaBODIPY–C60 tetrad (2)
was refluxed for 24 h and the solvent was removed under vacuum. The
residue was purified by column chromatography (silica) with 1:4 ethyl
acetate/CH2Cl2 as eluent to give the product. Yield: 0.014 g (70%);
1H NMR (400 MHz, CDCl3) d=8.02–8.12 (m, 8H), 8.00–7.86 (d, J=
12 Hz, 4H), 7.56–7.52 (d, J=8 Hz, 4H), 7.50–7.48 (m, 6H), 7.38–7.32 (d,
J=7 Hz, 4H), 6.85–6.71 (m, 3H), 6.68–6.64 (d, J=8 Hz, 1H), 6.34–6.28
(d, J=9 Hz, 1H), 4.90–4.86 (d, J=8 Hz, 1H), 4.80–4.70 (m, J=4 Hz,
4H), 4.72–4.64 (s, 1H), 4.48–4.38 (m, J=8 Hz, 4H), 4.14–4.10 (d, J=
8 Hz, 1H), 4.10–4.00 (m, 10H), 2.70–2.60 (s, 3H); UV/Vis: lmax =650 nm;
MALDI-TOF-MS (dithranol): m/z calcd for C135H55BFe2N4O6: 1951.29;
found: 1951.30 (see Figure S6 in the Supporting Information).
1-(4-Hydroxyphenyl)-3-phenylpropenone: Benzaldehyde (2.1 g, 2ꢃ
10À2 mol) 4-hydroxy acetophenone (2.69 g, 2ꢃ10À2 mol) and potassium
hydroxide (0.03 g, 6ꢃ10À4 mol) were dissolved in ethanol/water (85:15
v/v, 100 cm3) and stirred at room temperature for a period of 24 h. The
reaction mixture was allowed to cool in ice–water bath during which the
product precipitated. Filtration of the reaction mixture gave a pale white
solid product. Yield: 3.81 g (85%); 1H NMR (400 MHz, CDCl3): d=7.99
(m, 2H), 7.77 (m, 1H), 7.60, (m, 2H), 7.5 (m, 1H), 7.39 (m, 3H), 6.9 ppm
(m, 2H).
1-(4-Hydroxyphenyl)-4-nitro-3-phenylbutan-1-one: 1-(4-HydroxyphenACTHNUTRGENUGyN l)-
3-phenyl propenone (5.0 g, 2.2ꢃ10À2 mol), nitromethane (13.61 g,
0.223 mol), and diethylamine (8.12 g, 0.111 mol) were dissolved in dry
ethanol (35 cm3) and heated under reflux for 24 h. The solution was
cooled, acidified with 1m HCl to precipitate the compound. Yield: 4.58 g
(72%); 1H NMR (400 MHz, CDCl3): d=7.82 (d, J=8 Hz, 2H), 7.2 (m,
5H), 6.8 (d, J=7 Hz, 2H), 4.8 (m, 1H), 4.62 (m, 1H), 4.15 (m, 1H),
3.35 ppm (m, 2H).
Instruments: The UV/Vis spectral measurements were carried out with a
Shimadzu Model 2550 double monochromator UV/Vis spectrophotome-
ter. The fluorescence emission was monitored by using a Varian Eclipse
spectrometer. A right-angle detection method was used. The 1H NMR
studies were carried out on a Varian 400 MHz spectrometer. Tetra
AHCTUNGTREGUNyNN lsilane (TMS) was used as an internal standard.
ACHTUNGTRENNUNGmeth-
Crystal structure determination for compounds like 1a/2a and 2b was
carried out using a Bruker SMATR APEX2 CCD-based X-ray diffrac-
tometer equipped with a low temperature device and Mo-target X-ray
tube (wavelength=0.71073 ꢂ). Measurements were taken at 100(2) and
200 K, respectively.
[5-(4-Hydroxyphenyl)-3-phenyl-1H-pyrrol-2-yl]-[5-(4-hydroxyphenyl)-3-
phenylpyrrol-2-ylidene]amine (2a): A solution of 1-(4-hydroxyphenyl)-4-
nitro-3-phenylbutan-1-one (5 g, 1.8ꢃ10À2 mol) and ammonium acetate
(47.31 g, 0.61 mol) in ethanol (125 cm3) was heated under reflux for 24 h.
During the course of the reaction, the product precipitated as blue-black
solid. The reaction was allowed to cool to room temperature and solid
was filtered and washed with ethanol to give the product. Yield: 2.16 g
(51%); 1H NMR (400 MHz, CDCl3): d=8.04 (d, J=8 Hz, 4H), 7.84 (d,
J=7 Hz, 4H), 7.32 (m, 6H), 7.12 (s, 2H), 6.98 ppm (d, J=8 Hz, 4H).
Cyclic voltammograms were recorded on an EG&G PARSTAT electro-
chemical analyzer using a three-electrode system. A platinum button
electrode was used as the working electrode, a platinum wire served as
the counter electrode, and an Ag/AgCl electrode was used as the refer-
ence electrode. Ferrocene/ferrocenium redox couple was used as an inter-
nal standard. All the solutions were purged prior to electrochemical and
spectral measurements using argon gas. MALDI-TOF spectra of the tet-
rads were recorded in dichloromethane with an Applied Biosystems Voy-
ager-DE-STR using dithranol as a matrix (Supporting Information, Fig-
ure S9). The computational calculations were performed by DFT B3LYP/
3–21G* methods with GAUSSIAN 09 software package[21] on high speed
PCs.
BF2 chelate of [5-(4-hydroxyphenyl)-3-phenyl-1H-pyrrol-2-yl]-[5-(4-hy-
droxyphenyl)-3-phenylpyrrol-2-ylidene]amine (2b): Compound 2a (1 g,
2.07 mmol) was dissolved in dry CH2Cl2 (100 cm3). Diisopropylethyl-
ACHTUNGTRENNUNG
amine (2.71 g, 2.1ꢃ10À2 mol) and boron trifluoride diethyl etherate
(5.32 g, 0.037 mol) were added and the mixture was stirred at room tem-
perature under N2 for 24 h. The mixture was washed with water and the
organic layer was separated, dried over Na2SO4 and evaporated to dry-
ness. The residue was purified by column chromatography on silica gel
with CH2Cl2/ethyl acetate 4:1 to give metallic red solid. Yield: 0.76 g
(69%); 1H NMR (400 MHz, CDCl3): d=8.1 (m, 8H), 7.35 (m, 6H), 7.18
(s, 2H), 6.9 ppm (m, 4H) ppm; MS(MALDI-TOF): m/z calcd for
C32H22BF2N3O2: 529.18; found: 529.39; UV/Vis: lmax =699 nm.
Laser flash photolysis: The studied compounds were excited by a Panther
OPO pumped by Nd:YAG laser (Continuum, SLII-10, 4–6 ns fwhm) with
the powers of 1.5 and 3.0 mJ per pulse. The transient absorption meas-
urements were performed using a continuous xenon lamp (150 W) and
an InGaAs-PIN photodiode (Hamamatsu 2949) as a probe light and a de-
tector, respectively. The output from the photodiodes and a photomulti-
Fc2–azaBODIPY (2c): 4-Ferrocenylbenzoic acid (289.17 mg, 0.94 mmol)
was dissolved in DMF (20 cm3), to which EDCI (217.28 mg, 1.13 mmol)
was added at 08C under N2, followed by the addition of compound 2b
(100 mg, 0.2 mmol), after which the mixture was stirred for 24 h. Then
the solvent was removed under reduced pressure. The residue was dis-
solved in CH2Cl2 and the mixture was washed with water. The organic
layer was separated and dried over Na2SO4 and the solvent was evaporat-
ed. The residue was purified by column chromatography on silica gel
with CH2Cl2/hexanes (1:1) to give compound 2c. Yield: 50 mg ( 50%);
1H NMR (400 MHz, CDCl3): d=8.20–8.04 (m, 12H), 7.60–7.50 (m, 4H),
7.50–7.40 (m, 6H), 7.42–7.30 (d, J=6 Hz, 4H) 7.10–7.00 (s, 2H), 4.80–
4.70 (t, J=1.6 Hz, 4H), 4.50–4.40 (t, J=3.2 Hz, 4H), 4.18–4.10 (m, 10H);
UV/Vis: lmax =670 nm.
plier tube was recorded with
TDS3032, 300 MHz).
a digitizing oscilloscope (Tektronix,
Femtosecond transient absorption spectroscopy experiments were con-
ducted using an ultrafast source: Integra-C (Quantronix Corp.), an opti-
cal parametric amplifier: TOPAS (Light Conversion Ltd.) and a commer-
cially available optical detection system: Helios provided by Ultrafast
Systems LLC. The source for the pump and probe pulses were derived
from the fundamental output of Integra-C (780 nm, 2 mJ per pulse and
fwhm=130 fs) at a repetition rate of 1 kHz. 75% of the fundamental
output of the laser was introduced into TOPAS, which has optical fre-
quency mixers resulting in tunable range from 285–1660 nm, while the
rest of the output was used for white light generation. Typically, 2500 ex-
citation pulses were averaged for 5 s to obtain the transient spectrum at a
set delay time. Kinetic traces at appropriate wavelengths were assembled
from the time-resolved spectral data. All measurements were conducted
at 295 K.
Fc2–azaBODIPY–aldehyde (2d): Compound 2c (0.1 g, 0.10 mmol) was
dissolved in dry CH2Cl2 (20 cm3) and stirred under argon for 10 min.
Then AlCl3 (0.018 g, 0.135 mmol) was added and the solution was further
stirred for 15 min before addition of 3,4-dihydroxybenzaldehyde (0.018 g,
0.135 mmol). The mixture was stirred for 20 min and the solvent was
evaporated under reduced pressure. The crude product was purified by
column chromatography (deactivated basic alumina) with CH2Cl2/hex-
anes 3:1 to give the product. Yield: 0.077 g (64%); 1H NMR (400 MHz,
CDCl3): d=9.65–9.70 (s, 1H), 8.15–8.06 (m, 8H), 8.02–7.98 (d, J=8 Hz,
4H), 7.58–7.52 (m, J=8 Hz, 4H), 7.50–7.43 (m, 6H), 7.38–7.32 (d, J=
8 Hz, 4H), 6.86–6.78 (m, 3H), 6.68–6.62 (d, J=4 Hz, 1H), 6.32–6.28 (d,
J=8 Hz, 1H), 4.78–4.70 (m, J=7 Hz, 4H), 4.44–4.38 (t, J=4 Hz, 4H),
4.00–4.06 (s, 10H).
Acknowledgements
Support by the National Science Foundation (Grant No. CHE-1110942 to
F.D.), Grant-in-Aid (No. 20108010 to S.F. and 23750014 to K.O.), and the
Global COE (center of excellence) program of Osaka University from
MEXT, Japan (WCU R31-2008-000-10010-0), and NRF/MEST, Korea
(GRL 2010-00353) programs is acknowledged.
Fc2–azaBODIPY–C60 (2): Sarcosine (0.005 g, 6.2ꢃ10À5 mmol) and com-
pound 2d (0.015 g, 1.2ꢃ10À5 mmol) were added to a solution of C60
(0.026 g, 3.7ꢃ10À5 mmol), in dry toluene (100 cm3). The solution mixture
7228
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 7221 – 7230