Ion-Pair-Based Supramolecular Assemblies
FULL PAPER
0.12 mmol) in AcOH (9 mL) and the mixture was stirred at reflux for
9 h. When TLC monitoring showed complete consumption of the starting
diketone, the solvent was removed and the residue was chromatographed
on a column of silica gel (Wakogel C-300; eluent: 5% MeOH/CH2Cl2).
Concentration of the appropriate fraction and recrystallization of the res-
idue from CH2Cl2/n-hexane gave 1b as a pale-yellow solid (32.9 mg,
0.094 mmol, 78%). Rf =0.28 (eluent: 5% MeOH/CH2Cl2); 1H NMR
(600 MHz, [D6]DMSO, 208C): d=12.79 (brs, 1H; pyrazole-NH), 11.40
(brs, 2H; pyrrole-NH), 7.79–7.72 (m, 4H; Ar-H), 7.41–7.33 (m, 4H; Ar-
H), 7.22–7.14 (m, 2H; Ar-H), 6.87 (s, 1H; pyrazole-CH), 6.63 (brs, 1H;
pyrrole-H), 6.59 (brs, 1H; pyrrole-H), 6.57 (brs, 1H; pyrrole-H),
6.42 ppm (brs, 1H; pyrrole-H); UV/Vis (CH2Cl2): lmax (e)=325.5 nm
(3.8ꢂ104 mꢀ1 cmꢀ1); fluorescence (CH2Cl2): lex =326 nm; lem =375,
446 nm (sh); MALDI-TOF-MS: m/z (%): calcd for C23H18N4: 350.15
[M]+; found: 350.1 (100), 351.2 (82).
OCH2CH2), 1.77–1.73 (m, 4H; OCH2CH2), 1.48–1.47 (m, 12H;
OCH2CH2CH2), 1.36–1.26 (m, 96H; OC3H6C8H16CH3), 0.89–0.87 ppm
(m, 18H; OC11H22CH3); UV/Vis (CH2Cl2): lmax (e)=329.5 nm (7.0ꢂ
104 mꢀ1 cmꢀ1); fluorescence (CH2Cl2): lex =330 nm; lem =363, 379, 501 nm;
MALDI-TOF-MS: m/z (%) calcd for C95H162N4O6: 1455.25 [M]+; found:
1455.3 (100).
3,5-Bis[5-(3,4,5-trihexadecyloxyphenyl)pyrrol-2-yl]pyrazole (1 f): Hydra-
zine monohydrate (50 mL, 1.03 mmol) was added to
a solution of
1,3-bis[5-(3,4,5-trihexadecyloxyphenyl)pyrrol-2-yl]-1,3-propanedione[7]
(89.5 mg, 0.05 mmol) in AcOH (3 mL) and the mixture was stirred at
reflux for 5 h. When TLC monitoring showed complete consumption of
the starting diketone, the solvent was removed and the residue was flash
chromatographed on a column of silica gel (eluent: 1% MeOH/CH2Cl2).
Concentration of the appropriate fraction and recrystallization of the res-
idue from CH2Cl2/MeOH gave 1 f as
a pale-yellow solid (44.0 mg,
3,5-Bis[5-(3,4,5-trimethoxyphenyl)pyrrol-2-yl]pyrazole (1c): Hydrazine
monohydrate (267 mL, 5.50 mmol) was added to a solution of 1,3-bis-
0.025 mmol, 77%). Rf =0.43 (eluent: 1% MeOH/CH2Cl2); 1H NMR
(600 MHz, CDCl3, 208C; the pyrazole-NH signal could not be observed
at this temperature because of fast proton exchange between the adja-
cent N atoms): d=9.11 (brs, 2H; pyrrole-NH), 6.70 (s, 4H; Ar-H), 6.55
(s, 1H; pyrazole-CH), 6.52 (s, 2H; pyrrole-CH), 6.45 (s, 2H; pyrrole-
CH), 4.00–3.94 (m, 12H; OCH2), 1.82–1.80 (m, 8H; OCH2CH2), 1.77–
1.72 (m, 4H; OCH2CH2), 1.47–1.46 (m, 12H; OC2H4CH2), 1.34–1.25 (m,
144H; OC3H6C12H24CH3), 0.89–0.86 ppm (m, 18H; OC15H30CH3); UV/
Vis (CH2Cl2): lmax (e)=329.0 nm (6.2ꢂ104 mꢀ1 cmꢀ1); fluorescence
(CH2Cl2): lex =330 nm; lem =381, 508 nm; MALDI-TOF-MS: m/z (%)
calcd for C119H210N4O6: 1792.63 [M+H]+; found: 1791.6 (98), 1792.6
(100).
[5-(3,4,5-trimethoxyphenyl)pyrrol-2-yl]-1,3-propanedione[7]
(115.8 mg,
0.22 mmol) in AcOH (4 mL) and the mixture was stirred at reflux for
15 h. When TLC monitoring showed complete consumption of the start-
ing diketone, the solvent was removed and the residue was flash chroma-
tographed on a column of silica gel (eluent: 2% MeOH/CH2Cl2). Con-
centration of the appropriate fraction and recrystallization of the residue
from CH2Cl2/n-hexane gave 1c as
a pale-yellow solid (49.1 mg,
0.093 mmol, 42%). Rf =0.37 (eluent: 5% MeOH/CH2Cl2); 1H NMR
(600 MHz, [D6]DMSO, 208C): d=12.83 (brs, 1H; pyrazole-NH), 11.37
(brs, 2H; pyrrole-NH), 7.05 (s, 4H; Ar-H), 6.80 (s, 1H; pyrazole-CH),
6.60 (s, 3H; pyrrole-CH), 6.43 (brs, 1H; pyrrole-CH), 3.90–3.82 (m, 12H;
OCH3), 3.77–3.72 ppm (m, 6H; OCH3); UV/Vis (CH2Cl2): lmax (e)=
4-Bromo-1,2,3-trihexadecyloxybenzene:
A mixture of K2CO3 (6.11 g,
44.2 mmol), 4-bromo-1,2,3-trihydroxybenzene[20] (1.30 g, 6.32 mmol), and
1-bromohexadecane (6.56 g, 21.5 mmol) in dry DMF (50 mL) was stirred
at reflux for 3 days. After cooling, the solvent was evaporated. The crude
product was taken up in CH2Cl2, and the solution was washed with
water, dried over MgSO4, and concentrated to dryness. The residue was
then chromatographed on a column of silica gel (Wakogel C-300; eluent:
CH2Cl2/n-hexane, 1:5) to give 4-bromo-1,2,3-trihexadecyloxybenzene as a
white solid (4.65 g, 5.29 mmol, 84%). Rf =0.45 (eluent: CH2Cl2/n-hexane,
1:5); 1H NMR (600 MHz, CDCl3, 208C): d=7.15 (d, J=9.0 Hz, 1H; Ar-
H), 6.54 (d, J=9.0 Hz, 1H; Ar-H), 4.02 (t, J=6.0 Hz, 2H; OCH2), 3.96
(t, J=6.0 Hz, 2H; OCH2), 3.92 (t, J=6.0 Hz, 2H; OCH2), 1.83–1.72 (m,
6H; OCH2CH2), 1.50–1.43 (m, 6H; OC2H4CH2), 1.34–1.25 (m, 72H;
OC3H6C12H24CH3), 0.89–0.87 ppm (m, 9H; OC15H30CH3); MALDI-TOF-
MS: m/z (%) calcd for C54H101BrO3: 876.69 [M]+; found: 876.7 (100).
329.0 nm (4.7ꢂ104 mꢀ1 cmꢀ1); fluorescence (CH2Cl2): lex =329 nm; lem
=
364, 378, 494 nm; MALDI-TOF-MS: m/z (%) calcd for C29H30N4O6:
530.22 [M]+; found: 530.2 (100), 531.2 (28).
3,5-Bis[5-(3,4,5-trioctyloxyphenyl)pyrrol-2-yl]pyrazole (1d): Hydrazine
monohydrate (1.63 mL, 33.6 mmol) was added to a solution of 1,3-bis-
[5-(3,4,5-trioctyloxyphenyl)pyrrol-2-yl]-1,3-propanedione[7]
(467 mg,
0.42 mmol) in AcOH (4 mL) and the mixture was stirred at reflux for
35 h. When TLC monitoring showed complete consumption of the start-
ing diketone, the solvent was removed and the residue was flash chroma-
tographed on a column of silica gel (eluent: 1% MeOH/CH2Cl2). Con-
centration of the appropriate fraction and recrystallization of the residue
from CH2Cl2/MeOH gave 1d as a brown solid (309.1 mg, 0.28 mmol,
67%). Rf =0.22 (eluent: 1% MeOH/CH2Cl2); 1H NMR (600 MHz,
[D6]DMSO, 208C): d=12.79 (brs, 1H; pyrazole-NH), 11.33 (brs, 1H;
pyrrole-NH), 11.27 (brs, 1H; pyrrole-NH), 7.00 (s, 4H; Ar-H), 6.80 (s,
1H; pyrazole-CH), 6.55 (s, 3H; pyrrole-CH), 6.40 (brs, 1H; pyrrole-CH),
4.02 (t, J=6.6 Hz, 8H; OCH2), 3.83 (t, J=6.0 Hz, 4H; OCH2), 1.75–1.73
(tt, J=7.8, 6.6 Hz, 8H; OCH2CH2), 1.65–1.63 (tt, J=7.8, 6.6 Hz, 4H;
OCH2CH2), 1.48–1.42 (m, 12H; OC2H4CH2), 1.36–1.26 (m, 48H;
OC3H6C4H8CH3), 0.86–0.84 ppm (m, 18H; OC7H14CH3); UV/Vis
(CH2Cl2): lmax (e)=329.5 nm (6.1ꢂ104 mꢀ1 cmꢀ1); fluorescence (CH2Cl2):
lex =329 nm; lem =363, 380, 497 nm; MALDI-TOF-MS: m/z (%) calcd
for C71H115N4O6: 1119.88 [M+H]+; found: 1119.9 (100).
1-tert-Butoxycarbonyl-2-(2,3,4-trihexadecyloxyphenyl)pyrrole
and
2-(2,3,4-trihexadecyloxyphenyl)pyrrole: A solution of Na2CO3 (1.98 g,
18.7 mmol) in water (4 mL) was added to a solution of 4-bromo-1,2,3-tri-
hexadecyloxybenzene (4.55 g, 5.18 mmol), 1-tert-butoxycarbonylpyrrole-
2-boronic acid (1.31 g, 6.22 mmol), and [PdACHTNURTGNEUNG(PPh3)4] (370.0 mg,
0.32 mmol) in 1,2-dimethoxyethane (40 mL) at RT under nitrogen. The
mixture was heated at reflux for 6 h, cooled, and then partitioned be-
tween water and CH2Cl2. The organic phase was dried over anhydrous
MgSO4 and concentrated to give an oil, which was chromatographed on
a column of silica gel (Wakogel C-300; eluent: CH2Cl2/n-hexane, 1:2) to
give 1-tert-butoxycarbonyl-2-(2,3,4-trihexadecyloxyphenyl)pyrrole (1.91 g,
1.98 mmol, 38%) as a colorless oil. Rf =0.31 (eluent: CH2Cl2/n-hexane,
1:2); 1H NMR (600 MHz, CDCl3, 208C): d=7.31–7.30 (m, 1H; pyrrole-
CH), 6.92 (d, J=9.0 Hz, 1H; Ar-H), 6.62 (d, J=8.4 Hz, 1H; Ar-H), 6.19–
6.18 (m, 1H; pyrrole-CH), 6.09–6.08 (m, 1H; pyrrole-CH), 4.00–3.94 (m,
6H; OCH2), 1.81–1.74 (m, 6H; OCH2CH2), 1.50–1.42 (m, 6H;
OC2H4CH2), 1.36 (s, 9H; Boc), 1.34–1.25 (m, 72H; OC3H6C12H24CH3),
0.89–0.86 ppm (m, 9H; OC15H30CH3); MALDI-TOF-MS: m/z (%) calcd
for C63H113NO5: 963.86 [M]+; found: 963.3 (100). The product 1-tert-bu-
toxycarbonyl-2-(2,3,4-trihexadecyloxyphenyl)pyrrole (1.91 g, 1.98 mmol)
was heated at 1908C for 30 min. The residue was then chromatographed
on a column of silica gel (Wakogel C-300; eluent: CH2Cl2/n-hexane, 1:3)
to give 2-(2,3,4-trihexadecyloxyphenyl)pyrrole as a white solid (1.24 g,
1.43 mmol, 73%). Rf =0.33 (eluent: CH2Cl2/n-hexane, 1:3); 1H NMR
(600 MHz, CDCl3, 208C): d=9.78 (s, 1H; pyrrole-NH), 7.25 (d, J=
9.0 Hz, 1H; Ar-H), 6.81–6.80 (m, 1H; pyrrole-CH), 6.67 (d, J=9.0 Hz,
3,5-Bis[5-(3,4,5-tridodecyloxyphenyl)pyrrol-2-yl]pyrazole (1e): Hydrazine
monohydrate (953 mL, 19.6 mmol) was added to a solution of 1,3-bis-
[5-(3,4,5-tridodecyloxyphenyl)pyrrol-2-yl]-1,3-propanedione[7] (817.2 mg,
0.56 mmol) in AcOH (3 mL) and the mixture was stirred at reflux for
7 h. When TLC monitoring showed complete consumption of the starting
diketone, the solvent was removed and the residue was flash chromato-
graphed on a column of silica gel (eluent: 0.5% MeOH/CH2Cl2). Con-
centration of the appropriate fraction and recrystallization of the residue
from CH2Cl2/MeOH gave 1e as a brown solid (305.8 mg, 0.21 mmol,
38%). Rf =0.20 (eluent: 0.5% MeOH/CH2Cl2); 1H NMR (600 MHz,
CDCl3, 208C; the pyrazole-NH signal could not be observed at this tem-
perature because of fast proton exchange between the adjacent N atoms;
other solvents such as [D6]DMSO make the pyrazole-NH signal more
evident, as observed for 1b–d and 2d): d=8.87 (brs, 2H; pyrrole-NH),
6.70 (s, 4H; Ar-H), 6.55 (s, 1H; pyrazole-CH), 6.52 (s, 2H; pyrrole-CH),
6.46 (s, 2H; pyrrole-CH), 4.03–3.95 (m, 12H; OCH2), 1.84–1.80 (m, 8H;
Chem. Eur. J. 2013, 00, 0 – 0
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
5
&
ÞÞ
These are not the final page numbers!