8756 J . Org. Chem., Vol. 65, No. 25, 2000
Shiratori et al.
tramolecular ET. The F--coordinated boronate-bridge
provides two major effects: (1) the coordinated boronate-
bridge has a lifted LUMO orbital that is unfavorable for
so-called superexchange interaction between the donor
and acceptor, leading to the suppression of the ET, and
(2) the negative charge at the boronate-bridge exerts
electrostatic interaction with the photogenerated ion-pair
state, which is negligible in DMF but significant in
benzene. Collectively, almost complete switching of ET-
path is achieved in the triad 18. More detailed mecha-
nistic study and further extension of this strategy to more
sophisticated supramolecular systems are now actively
in progress in our laboratories.
soluble solids and evaporated to give 23 as white solids (255
mg, 0.441 mmol) in 89% isolated yield: mp >300 °C; IR (KBr)
νmax (cm-1) 1722 (CdO of PI) and 1128 (C-O of acetal); 1H
NMR (CDCl3) 10.06 (s, 1H, CHO), 8.42 (s, 2H, PI-ArH), 7.93
(d, J ) 8.2 Hz, 2H, p-phenylene-ArH), 7.71 (d, J ) 8.2 Hz,
2H, p-phenylene-ArH), 7.57 (d, J ) 8.5 Hz, 1H, di-tert-
butylphenyl-ArH), 7.49 (dd, J ) 8.5, 2.4 Hz, 1H, di-tert-
butylphenyl-ArH), 6.94 (d, J ) 2.1 Hz, 1H, di-tert-butylphenyl-
ArH), 5.72 (s, 1H, acetal-CH), 4.85 (tt, J ) 11.1, 5.4 Hz, 1H,
acetal-CH), 4.69 (t, J ) 11.1, 2H, acetal-CH2), 4.27 (dd, J )
10.7, 4.9 Hz, 2H, acetal-CH2), 1.31 (s, 9H, tert-butyl), and 1.28
(s, 9H, tert-butyl); MS (FAB) m/z 594, calcd for C35H34N2O7,
594. Anal. Calcd for C35H34N2O7, C, 70.69; H, 5.76; N, 4.71.
Found: C, 70.7; H, 5.8; N, 4.7.
P I-ZP -B(OH)2 25a . Zinc porphyrin 25a was prepared
according to the method for synthesis of zinc porphyrin 7 using
PI-appended benzaldehyde 23 (173 mg, 0.30 mmol), 4-formyl-
phenylboronic acid (47 mg, 0.31 mmol), dipyrrylmethane 5 (266
mg, 0.66 mmol), trichloroacetic acid (12 mg, 73 µmol), and
p-chloranil (222 mg, 0.90 mmol) to give zinc porphyrin 25a
(108 mg, 74 µmol) in 25% isolated yield. Flash column
chromatography on silica gel was performed using CH2Cl2 as
an eluant: IR (KBr) νmax (cm-1) 1724 (CdO) 1373 (B-O of
Exp er im en ta l Section
Ma ter ia ls a n d Ap p a r a tu s. All commercially available
materials were used without further purification unless oth-
erwise stated. THF and ether were distilled from sodium-
benzophenone ketyl. DMF was dried over molecular sieve 4A
for 1 day and distilled under reduced pressure. CH2Cl2 was
distilled from P2O5. Pyridine and triethylamine were dried over
KOH for several days and distilled. Toluene was distilled from
CaH2. Anhydrous tetra-n-butylammonium fluoride (TBAF)
was prepared by heating TBAF‚3H2O at 50 °C for 1 day in
vacuo. Solvents used for spectroscopic measurements were all
spectrograde. Preparative separations were usually performed
by flash column chromatography (Merck, Kieselgel 60H, Art.
7736) and gravity column chromatography (Wako, Wakogel
C-200).
1H NMR (500 MHz) and 11B NMR (160 MHz) spectra were
recorded on a J EOL ALPHA-500 FT-NMR spectrometer, and
chemical shifts were reported in the δ scale relative to
tetramethylsilane for 1H and to trimethylborate for 11B,
respectively. IR spectra were recorded on a J ASCO FT/IR-350
spectrometer. Melting points were not corrected. FAB mass
spectra were measured on a J EOL HX-110 spectrometer using
positive-FAB ionization method and 3-nitrobenzyl alcohol
matrix. MALDI-TOF mass spectra were measured on a Shi-
madzu/KRATOS MALDI 4 spectrometer. UV-vis absorption
spectra were recorded on a Shimadzu UV-2400PC UV-vis
spectrophotometer. Steady-state fluorescence spectra were
recorded on a Shimadzu PF-5300PC spectrometer. Steady-
state UV-vis absorption and fluorescence spectra were taken
with 1 × 106 M-1 solutions at room temperature. Fluorescence
lifetimes were measured with 2 × 10-5M solutions by using a
picosecond time-correlated single photon counting system for
excitation at 532 nm and monitoring at 620 nm emission.25
Picosecond time-resolved transient absorption spectra were
measured on Ar-bubbled 2.5 × 10-5 M solutions by using a
mode-locked Nd3+:YAG laser system (Continuum PY61C-10,
fwhm: 17 ps) with second harmonic output at 532 nm for
excitation.26 Nanosecond time-resolved transient absorption
spectra were measured by using Q-switched Nd3+:YAG laser
(Quantel YG 580, fwhm: 5 ns) with second harmonic output
at 532 nm for excitation.27
1
B(OH)2) and 1122 (C-O of acetal); H NMR (CDCl3) δ 10.19
(s, 2H, meso), 8.47 (s, 2H, PI-ArH), 8.46 (d, J ) 7.9 Hz, 2H,
p-phenylene-ArH), 8.25 (d, J ) 7.6 Hz, 2H, p-phenylene-ArH),
8.15 (d, J ) 7.7 Hz, 2H, p-phenylene-ArH), 7.92 (d, J ) 7.9
Hz, 2H, p-phenylene-ArH), 7.59 (d, J ) 8.5 Hz, 1H, di-tert-
butylphenyl-ArH), 7.51 (dd, J ) 8.7, 2.3 Hz, 1H, di-tert-
butylphenyl-ArH), 6.98 (d, J ) 2.1 Hz, 1H, di-tert-butylphenyl-
ArH), 6.06 (s, 1H, acetal-CH), 5.06 (tt, J ) 10.7, 5.3 Hz, 1H,
acetal-CH), 4.89 (t, J ) 10.8 Hz, 2H, acetal-CH2), 4.45 (dd, J
) 10.3, 5.0 Hz, 2H, acetal-CH2), 3.95 (m, 8H, porphyrin-hexyl-
CH2), 2.48 (s, 6H, porphyrin-methyl), 2.47 (s, 6H, porphyrin-
methyl), 2.17 (m, 8H, porphyrin-hexyl-CH2), 1.74 (m, 8H,
porphyrin-hexyl-CH2), 1.49 (m, 8H, porphyrin-hexyl-CH2), 1.38
(m, 8H, porphyrin-hexyl-CH2), 1.33 (s, 9H, tert-butyl), 1.31 (s,
9H, tert-butyl), 0.91 (t, J ) 7.3 Hz, 6H, porphyrin-hexyl-CH3),
and 0.91 (t, J ) 7.0 Hz, 6H, porphyrin-hexyl-CH3); MS
(MALDI-TOF) m/z 1451, calcd for C88H105N6O8BZn, 1449. Anal.
Calcd for C88H105N6O8Zn, C, 72.84; H, 7.29; N, 5.79. Found:
C, 73.0; H, 7.4; N, 5.8.
5-(4-Dih yd or oxybor ylp h en yl)-15-[4-(5,5-d im et h yl-1,3-
d ioxa n -2-yl)p h en yl]-2,8,12,18-tetr a -n -h exyl-3,7,13,17-tet-
r a m eth ylp or p h in a tozin c(II) (25b). Zinc porphyrin 25b was
prepared according to the method for synthesis of zinc por-
phyrin 7 using 4-(5,5-dimethyl-1,3-dioxan-2-yl)benzaldehyde
24 (67 mg, 0.30 mmol), 4-formylphenylboronic acid (46 mg, 0.31
mmol), dipyrrylmethane 5 (228 mg, 0.67 mmol), trichloroacetic
acid (10 mg, 61 µmol), and p-chloranil (221 mg, 0.90 mmol) to
give zinc porphyrin 25b (48.6 mg, 45 µmol) in 15% isolated
yield. Flash column chromatography on silica gel was per-
formed using 1.5% methanol in CH2Cl2 as an eluant: IR (KBr)
νmax (cm-1) 1373 (B-O of B(OH)2) and 1105 (C-O of acetal);
1H NMR (CDCl3) δ 10.12 (s, 2H, meso), 8.11 (d, J ) 7.8 Hz,
2H, p-phenylene-ArH), 8.10 (d, J ) 7.6 Hz, 2H, p-phenylene-
ArH), 8.08 (d, J ) 7.8 Hz, 2H, p-phenylene-ArH), 7.89 (d, J )
8.0 Hz, 2H, p-phenylene-ArH), 5.77 (s, 1H, acetal-CH), 3.99
(d, J ) 10.7 Hz, 2H, acetal-CH2), 3.92 (m, 8H, porphyrin-hexyl-
CH2), 3.87 (m, 8H, porphyrin-hexyl-CH2),2.45 (s, 6H, porphy-
rin-methyl), 2.41 (s, 6H, porphyrin-methyl), 2.17 (m, 8H,
porphyrin-hexyl-CH2), 1.74 (m, 8H, porphyrin-hexyl-CH2), 1.50
(s, 3H, acetal-CH3), 1.50 (m, 8H, porphyrin-hexyl-CH2), 1.41
(m, 8H, porphyrin-hexyl-CH2), 0.96 (s, 3H, acetal-CH3), 0.93
(t, J ) 7.3 Hz, 6H, porphyrin-hexyl-CH3), and 0.92 (t, J ) 7.3
Hz, 6H, porphyrin-hexyl-CH3); MS (FAB) m/z 1076, calcd for
Syn th esis. Here, we described the synthetic details of triad
18. Other synthetic procedures are given in Supporting
Information.
N-(2,5-Di-ter t-bu tylp h en yl)-N′-[2-(4-fr om ylp h en yl)-1,3-
d ioxa n -4-yl]p yr om ellitic Diim id e (23). PI-appended diol 22
(238 mg, 0.497 mmol), terephthalaldehyde (204 mg, 1.52
mmol), and p-toluenesulfonic acid (54 mg, 0.28 mmol) were
dispersed in benzene (30 mL), and the reaction mixture was
refluxed for 2 h. After the mixture was cooled, the precipitating
white solids were collected by filtration and dissolved again
in CH2Cl2. The CH2Cl2 solution was filtered to remove in-
C
66H87N4O4BZn, 1075. Anal. Calcd for C66H87N4O4BZn, C,
73.63; H, 8.14; N, 5.20. Found: C, 74.1; H, 8.2; N, 5.1.
Tr ia d P I′-ZP -NI′ 18. Triad 18 was prepared according
to the method for the synthesis of 1c using PI-ZP-B(OH)2
25a (73.7 mg, 51 µmol) and NI-appended diol 26 (27.2 mg, 52
µmol) to give triad 18 (85.0 mg, 44 µmol) in 86% isolated
yield: IR (KBr) νmax (cm-1) 1720 (CdO of PI and NI), 1315
(B-O of boronate) and 1130 (C-O of acetal). 1H NMR (CDCl3)
δ 10.19 (s, 2H, meso), 8.88 (d, J ) 7.6 Hz, 2H, NI-ArH), 8.86
(25) Yamazaki, I.; Tamai, N.; Kume, H.; Tsuchiya, H.; and Oba. K.
Rev. Sci. Instrum. 1985, 56, 1187.
(26) Yoshimura, A.; Nozaki, K.; Ikeda, N.; Ohno, T. J . Phys. Chem.
1996, 100, 1630.
(27) Ohno, T.; Nozaki, K.; Haga, M. Inorg. Chem. 1991, 30, 767.