performed on a Flash EA 1112 analyzer. Scanning electron
microscopy (SEM) was performed on a JEOL model JSM-6700F
FE-SEM and a Hitachi S-4800 FE-SEM operating at 5 kV.
Samples for SEM measurement were prepared by dropping the
suspension onto a silicon substrate followed by air drying and
coating with Pt; transmission electron microscopy (TEM) was
obtained on a Hitachi H-800 electron microscope and a JEOL
model JEM-1011 electron microscope operating at 100 kV.
Samples for TEM measurement were prepared by dropping the
suspension onto 200 mesh copper grids followed by air-drying.
EDX spectra were recorded with a Hitachi S-4800 SEM equip-
ped with Horiba-EMAX450 energy dispersive X-ray analyzer
operating at an accelerating voltage of 15 kV. Powder X-ray
diffraction data were collected on a Rigaku model RINT Ultima
III diffractometer by depositing powder on glass substrate, from
2q ¼ 1.5ꢁ to 60ꢁ with 0.02ꢁ increments at 25 ꢁC. UV-vis
absorption spectra were obtained on a Shimadzu UV-vis spec-
trophotometer model UV-1601 PC. Fluorescence spectra were
recorded on a Hitachi F-4500 spectrometer.
overnight. A large amount of precipitate was formed. Filtration
and washing with acetone afforded PyPA-Cl as a colorless solid
(0.49 g, 95%). 1H NMR (400 MHz, DMSO-d6, ppm): d 8.42–8.11
(m, 11H), 8.07 (d, 1H), 7.81 (d, 2H), 7.22 (d, 2H), 4.25 (t, 2H),
3.06 (br, 2H), 2.18 (m, 2H). 13C NMR (100 MHz, DMSO-d6,
ppm): d 158.50, 137.49, 133.29, 132.06, 131.62, 131.04, 130.50,
128.31, 128.18, 128.02, 127.89, 127.02, 125.91, 125.56, 125.51,
125.29, 124.83, 124.71, 115.29, 65.25, 36.77, 27.37.
Synthesis of PyPA-Br. To a solution of 5 (0.10 g, 0.22 mmol) in
THF (3.0 mL) hydrobromic acid (1.0 mL, 10 M) was added. The
mixture was stirred at room temperature for 12 h. After the
addition of acetone (30.0 mL), the mixture was placed in a fridge
overnight. A large amount of precipitate was formed. Filtration
and washing with acetone afforded PyPA-Br as a colorless solid
1
(0.086 g, 90%). H NMR (400 MHz, DMSO-d6, ppm): d 8.39–
8.01 (m, 9H), 7.92 (s, 3H), 7.60 (d, 2H), 7.22 (d, 2H), 4.24 (t, 2H),
3.09 (t, 2H), 2.16 (m, 2H). 13C NMR (100 MHz, DMSO-d6,
ppm): d 158.50, 137.55, 133.42, 132.13, 131.70, 131.11, 130.58,
128.39, 128.24, 128.08, 127.97, 127.08, 125.98, 125.62, 125.57,
125.33, 124.91, 124.79, 115.39, 65.44, 37.12, 27.57.
Synthesis of tert-butyl 3-(4-bromophenoxy)propyl-carbamate
(3). A mixture of 1 (10.0 g, 0.052 mol), 2 (11.0 g, 0.064 mol), KI
(5.0 g, 0.030 mol), K2CO3 (30.0 g, 0.217 mol) and butanol
(300 mL) was heated to reflux and stirred under a nitrogen
atmosphere overnight; CH2Cl2 was added. The mixture was
washed with a large portion of aqueous NaOH solution several
times, and the organic layer was separated and dried over
anhydrous Na2SO4. After the removal of the solvent, the residue
was recrystallized in n-hexane and ethyl ether to afford 3 as
Synthesis of PyPA-SO4. To a solution of 5 (0.10 g, 0.22 mmol)
in THF (3.0 mL) concentrated sulfuric acid (1.0 mL, 10 M) was
added. The mixture was stirred at room temperature for 24 h.
After the addition of acetone (30.0 mL), the mixture was placed
in a fridge overnight. A large amount of precipitate was formed.
Filtration and washing with acetone afforded PyPA-SO4 as
a colorless solid (0.074 g, 83%). 1H NMR (400 MHz, DMSO-d6,
ppm): d 8.40–8.02 (m, 9H), 7.84 (s, 3H), 7.61 (d, 2H), 7.22
(d, 2H), 4.24 (t, 2H), 3.09 (br, 2H), 2.14 (m, 2H). 13C NMR
(100 MHz, DMSO-d6, ppm): d 158.50, 137.55, 133.43, 132.13,
131.70, 131.11, 130.59, 128.40, 128.24, 128.08, 127.97, 127.10,
125.99, 125.62, 125.58, 125.33, 124.91, 124.79, 115.39, 65.41,
37.21, 27.59.
1
a colorless solid (11.2 g, 66%). H NMR (400 MHz, CDCl3,
ppm): d 7.36 (d, 2H), 6.77 (d, 2H), 4.72 (s, 1H), 3.98 (t, 2H), 3.31
(m, 2H), 1.95 (m, 2H), 1.44 (s, 9H). 13C NMR (100 MHz, CDCl3,
ppm): d 158.03, 156.15, 132.43, 116.41, 113.10, 93.92, 66.14,
38.01, 29.66, 28.56. Anal. calcd. for C14H20BrNO3: C, 50.92; H,
6.10; N, 4.24. Found: C, 50.91; H, 6.21; N, 4.46.
Synthesis of tert-butyl 3-(4-(pyren-6-yl)phenoxy)propyl-carba-
mate (5). A mixture of 3 (1.0 g, 3.0 mmol), 4,4,5,5-tetramethyl-2-
(pyren-6-yl)-1,3,2-dioxaborolane 4 (1.2 g, 3.6 mmol), NaHCO3
(0.5 g, 6.0 mmol), THF (25 mL), and H2O (11 mL) was carefully
degassed before and after Pd(PPh3)4 (35 mg, 0.030 mmol) was
added. The mixture was heated to reflux and stirred under
a nitrogen atmosphere overnight. CH2Cl2 (150 mL) and brine
was added, and the organic layer was separated and dried over
anhydrous Na2SO4. After the removal of the solvent, the residue
was purified by chromatography on a silica gel column eluting
Results and discussion
The synthesis of PyPA-X (X ¼ Cl, Br, and SO4) is quite
straightforward and the synthetic route is shown in Fig. 2. Mono
bromide 3 carrying a tert-butyloxycarbonyl (Boc) protected
amino group was prepared by the reaction of commercially
available tert-butyl-3-chloropropylcarbamate 1 and 4-bromo-
phenol 2 under Williamson etherification conditions with K2CO3
as the base, KI as the catalyst, and butanol as the solvent. Boc
protected compound 5 was synthesised in a yield of 81% by
Suzuki–Miyaura cross-coupling of pyrene mono boronic acid
ester 4 and mono bromide 3 in a biphasic mixture of THF and
aqueous NaHCO3 with Pd(PPH3)4 as a catalyst precursor. After
deprotection of compound 5 with concentrated aqueous HCl,
HBr or H2SO4, the desired molecules PyPA-Cl, PyPA-Br and
PyPA-SO4, were obtained in yields of 95%, 90% and 83%,
respectively. The structures of all new compounds were unam-
1
with CH2Cl2 to afford 5 as a green solid (1.1 g, 81%). H NMR
(400 MHz, CDCl3, ppm): d 8.22–8.15 (m, 4H), 8.09 (s, 2H), 8.03–
7.96 (m, 3H), 7.56 (d, 2H), 7.10 (d, 2H), 4.82 (s, 1H), 4.16 (t, 2H),
3.41 (m, 2H), 2.04 (m, 2H), 1.48 (s, 9H). 13C NMR (100 MHz,
CDCl3, ppm): d 158.35, 156.24, 137.57, 133.87, 131.75, 131.16,
130.53, 128.73, 127.84, 127.50, 126.14, 125.50, 125.00, 119.13,
114.56, 46.97, 38.42, 29.81, 28.61. Anal. calcd. for C30H29NO3:
C, 79.80; H, 6.47; N, 3.10. Found: C, 79.47; H, 6.52; N, 3.30.
1
biguously confirmed by H and 13C NMR spectroscopy, and all
except for the cationic ammonium salts PyPA-Cl, PyPA-Br and
PyPA-SO4 were also verified by elemental analysis.
Synthesis of PyPA-Cl. To a solution of 5 (0.60 g, 1.33 mmol) in
THF (5.0 mL) hydrochloric acid (1.0 mL, 10 M) was added. The
mixture was stirred at room temperature for 12 h. After the
addition of acetone (30.0 mL), the mixture was placed in a fridge
The precipitation technique is a very useful method in the self-
assembly of nanostructures. Nanosized aggregates can be formed
by slowly diffusing a poor solvent into a solution of good solvent.
4928 | J. Mater. Chem., 2012, 22, 4927–4931
This journal is ª The Royal Society of Chemistry 2012