Complexes 7–11 (except 10) have the low UIC values, showing
minimal loss of energy by non-radiative decay from the excited
singlet state. The complexes showed reasonably long triplet life-
times with tT 7510, 3190, 2880, 2370, 9470 ms, respectively. These
are longer triplet lifetimes than normal for phthalocyanines,22
hence show that these complexes have an excellent potential
as photosensitizers. The tT values for ball-type phthalocyanines
are generally lower than for the corresponding mononuclear
derivatives (compare 7 and 9), probably due to self quenching
of the rings in the former. The tT values for the complexes are very
long (in the ms range) compared to phthalocyanines in general.22
These are indeed the longest triplet lifetimes ever reported for
phthalocyanine complexes.24,25 Triplet lifetime values of near 40 ms
were obtained for phenoxy or benzyloxy tetrasubstituted oxotita-
nium phthalocyanines. For ZnPc derivatives tetrasubstituted with
pyridyloxy, the triplet lifetimes were 7 ms in DMF and 350 ms in
DMSO. MPc complexes with tT of ~ 1.5 ms are known,25 but the
values reported here are much longer ranging from ~ 2.4 to 9.5 ms.
lifetimes were determined by exponential fitting of the kinetic
curves using the program OriginPro 7.1.
3.3 Synthesis
The target precursors were prepared by a nucleophilic aromatic
substitution reaction between 4-nitrophthalonitrile 1 or 1,2-
dichloro-4,5-dicyanobenzene 2 and 1,1¢-binaphthyl-8,8¢-diol 3,
Scheme 1.
3.3.1. General Procedure for 4–6. Compound 3 (3.31 g, 11.55
mmol) was dissolved in dry DMSO (15 mL) and 1 (2 g, 11.55 mmol
for 4, 4 g, 23.1 mmol for 5), or 2 (1.0 g, 5.1 mmol for 6) was added
under inert atmosphere. To this reaction mixture, finely ground
anhydrous potassium carbonate (1.60 g, 11.55 mmol for 4, 3.2 g,
23.00 mmol for 5, 2.8 g, 20.3 mmol for 6) was added. After 4 h of
stirring at room temperature, further potassium carbonate (0.40 g,
2.88 mmol for 4, 0.79 g, 5.8 mmol for 5, 0.70 g, 5.1 mmol for 6) was
added and this same amount was added again after 24 h of stirring.
After a total of 48 h, 96 h and 7 days of stirring, for 4, 5 and 6,
respectively, the reaction mixture was poured into water (50, 50
and 175 mL) resulting in the formation of light yellow precipitates
for 4–6, respectively. The crude product was centrifuged and was
further purified by chromatography over a silica gel column using
a CHCl3 as eluent. The product was recrystallized from ethanol
and then the pure product was dried using P2O5 for two weeks.
3. Experimental
3.1 Materials
Silicon(IV) tetraacetate, titanium(IV) butoxide and zinc(II) ac-
etate were purchased form Sigma–Aldrich. Dimethylsulfoxide
(DMSO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), dimethylfor-
mamide (DMF), dichloromethane (DCM) and chloroform were
purchased from Saarchem. Silica gel for column chromatography
was purchased from MERCK. All other reagents were obtained
from commercial suppliers and used as received. All solvents were
dried and purified as described by Perrin and Armarego.26
4-(8¢-Hydroxy-1,1¢-binaphthyl-8-yloxy)phthalonitrile (4). The
product is white in colour. Yield: 2.0 g, 42%. Mp. 113 ◦C. IR
(KBr) (nmax/cm-1): 3465 (Ar–OH), 3054 (Ar–CH), 2232 (C N),
1586 (C C), 1246 (C–O–C). 1H NMR (DMSO-d6): d, ppm 8.20
(2H, d, J = 9.2 Hz, Ar–H), 8.08 (1H, d, J = 8.0 Hz, Ar–H), 7.85
(2H, d, J = 8.4 Hz, Ar–H), 7.70 (1H, b, OH), 7.55 (2H, t, J = 7.4
Hz, Ar–H), 7.48 (2H, d, J = 7.2 Hz Ar–H), 7.46 (1H, s, Ar–H),
7.38 (2H, t, J = 7.4 Hz, Ar–H), 7.16 (1H, d, J = 8.0 Hz, Ar–H),
6.93 (2H, d, J = 7.6 Hz, Ar–H). Calcd for C28H15N2O2: C, 81.54;
H, 3.91; N, 6.79%. Found: C, 81.48; H, 3.91; N, 6.80%. MS m/z
Calculated: 412.12. Found [M]+: 412.37.
3.2 Equipment
UV-Vis absorption spectra were obtained using the Varian Cary
500 UV-Vis/NIR spectrophotometer. Fluorescence excitation and
emission spectra were recorded with a Varian Eclipse spectropho-
tometer. FT-IR data (ATR) were recorded using the Perkin–
4,4¢-(1,1¢-Binaphthyl-8,8¢-diylbis(oxy))diphthalonitrile (5).
A
light yellow solid was obtained. Yield: 2.1 g, 34%. Mp. 150 ◦C.
IR (KBr) (nmax/cm-1): 3072 (Ar–CH), 2232 (C N), 1586 (C C),
1278 (C–O–C). 1H NMR (DMSO-d6): d, ppm 8.20 (2H, d, J = 8.8
Hz, Ar–H), 8.08 (2H, d, J = 8.4 Hz, Ar–H), 7.85 (2H, d, J = 8.8 Hz,
Ar–H), 7.55 (2H, t, J = 7.8 Hz, Ar–H), 7.49 (2H, s, Ar–H), 7.39
(2H, t, J = 7.2 Hz, Ar–H), 7.30 (2H, d, J = 8.4 Hz, Ar–H), 7.16
(2H, d, J = 8.0 Hz, Ar–H), 6.93 (2H, d, J = 8.4 Hz, Ar–H). Calcd
for C36H18N4O2: C, 80.29; H, 3.37; N,10.40%. Found: C, 80.24; H,
3.37; N, 10.37%. MS m/z Calculated: 538.55. Found [M]+: 538.0.
1
Elmer spectrum 100 FTIR spectrometer. H NMR spectra were
obtained using a Bruker EMX 400 MHz spectrometer. Elemental
analysis were done on a Finnigan Flash EA 1112 Series Elementar.
Mass spectra data were collected with a Bruker AutoFLEX
III Smartbeam MALDI TOF/TOF Mass spectrometer. The
instrument was operated in positive ion mode using a m/z range
of 400–3000. The voltage of the ion sources were set at 19 and
16.7 kV for ion sources 1 and 2, respectively, while the lens was
set at 8.50 kV. The reflector 1 and 2 voltages were set at 21 and 9.7
kV, respectively. The spectra were acquired using dithranol as the
MALDI matrix, using a 354 nm nitrogen laser.
4,5-(1,1¢-Binaphthyl-8,8¢-diyldi(oxy)phthalonitrile (6). A white
solid was obtained. Yield: 1.2 g, 20%. IR (KBr) (nmax/cm-1): 3085
1
(Ar–CH), 2238 (C N), 1577 (C C), 1276 (C–O–C). H NMR
Triplet absorption and decay kinetics were recorded on a laser
flash photolysis system, the excitation pulses were produced by
a Quanta-Ray Nd : YAG laser providing 400 mJ, 9 ns pulses of
laser light at 10 Hz, pumping a Lambda-Physik FL 3002, dye
(Pyridin 1 in methanol). The analyzing beam source was from a
Thermo Oriel xenon arc lamp, and a photomultiplier tube was
used as a detector. Signals were recorded with a two-channel
300 MHz digital real-time oscilloscope (Tektronix TDS 3032C);
kinetic curves were averaged over 256 laser pulses. The triplet
(DMSO-d6): d, ppm 8.62 (2H, s, Ar–H), 8.23 (2H, d, J = 9.2 Hz,
Ar–H), 8.13 (2H, d, J = 8.0 Hz Ar–H), 7.67 (2H, d, J = 8.8 Hz
Ar–H), 7.61 (2H, t, J = 8.4 Hz Ar–H), 7.51 (2H, t, J = 8.4 Hz
Ar–H), 7.37 (2H, d, J = 8.4 Hz Ar–H). Calcd for C28H14N2O2: C,
81.94; H, 3.44; N, 6.83%. Found: C, 81.99; H, 3.45; N, 6.84%. MS
m/z Calculated: 410.42. Found [M]+: 410.12.
3.3.2. General procedure for 7–11. A mixture of complex 4–6
(0.500 g, 1.21 mmoL for 4, 1.22 mmoL for 5, 0.93 mmoL for 6),
5288 | Dalton Trans., 2011, 40, 5285–5290
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The Royal Society of Chemistry 2011
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