face-to-face stacked aggregates too, this aggregation is an
intramolecular process, but it is seriously affected by the inter-
molecular aggregation. The peripherally connected long alkyl
chains in hexamer 2 have enhanced significantly the hydrophobic
interactions between adjacent molecules, but they also disrupt
the p–p interaction. This competition between different driving
forces for the molecular aggregation of hexamer 2 hinders it from
forming large molecular aggregates. This finding revealed that it
is possible to control the morphology and size of molecular
aggregates by programming the competition between different
weak intermolecular interactions.
N2 for 10 min. Diethylene triamine (10 mg, 0.1 mmol) were
added dropwise to the reaction mixture. After reacting for
another 0.5 h at this temperature, the solvent was evaporated
under reduced pressure and the residue was dissolved in chlo-
roform and washed with water to remove imidazole. The chlo-
roform was removed and the residue was purified by column
chromatography on silica gel (methanol/chloroform ¼ 5 : 95, v/v
1
as eluent) to give compound 3 (247.3 mg, 87%). H NMR (300
MHz, CDCl3): d ¼ 9.28 (d, 2H), 9.15 (d, 2H), 8.19 (d, 2H), 8.10
(m, 4H), 8.01 (s, 2H), 7.50 (d, 8H), 7.10 (d, 8H), 7.03 (t, 2H), 6.99
(s, 4H), 4.45 (t, 4H), 4.18 (t, 4H), 3.91 (t, 12H), 3.87 (s, 1H), 3.78
(br, 4H), 2.33–2.35 (t, 4H), 1.8–1.2 (m, 156H), 0.87 (m, 18H). MS
(MALDI-TOF): m/z, calculated for C182H237N7O20: 2842.96,
found 2843.88 [M+]; Elemental analysis (%) calculated for
C182H237N7O20: C 76.89, H 8.40, N 3.45; found: C 76.65, H 8.26,
N 3.42.
Experimental
General method
1H NMR spectra were recorded at 300 MHz with the solvent
peak as the internal standard (in CDCl3). Electronic absorption
spectra were recorded on a Hitachi 4100 spectrometer. Fluores-
cence spectra were measured on an ISS K2 system. Fluorescence
quantum yields were calculated with N,N0-dicyclohexyl-1,7-di(p-
t-butyl-phenoxyl)-3,4,9,10-tetracarboxylic diimide (Ff ¼ 100%)
as the standard, all samples were excited at 478 nm. MALDI-
TOF mass spectra were obtained on Bruker BIFLEX III mass
spectrometer with acyano-4-hydroxycinnamic acid as matrix.
The morphology of the dried gel on Si was studied in air by use of
a Veeco multimode atomic force microscope (AFM) in tapping
mode. The low-angle X-ray diffraction (LAXD) experiment was
carried out on a Rigaku D/max-gB X-ray diffractometer.
Preparation of hexamer 2
To a mixture of compound 3 (376 mg, 0.15 mmol) and 20 mL
CH2Cl2, trimesoyl chloride was added dropwise with continuous
stirring at room temperature. The resulting mixture was stirred
continually at room temperature under a nitrogen atmosphere
overnight. After the solvent was evaporated, the residue was
purified by column chromatography on silica gel (CH2Cl2 as
eluent) to give hexamer 2. In the 1H NMR spectrum of
compound 2 in CDCl3 (c ¼ 10ꢁ4 M), very broad peaks were
observed, suggesting the formation of molecular aggregates.36 1
H
NMR (300 MHz, CDCl3): d ¼ 9.28 (s, broad, 12H), 8.35 (s,
broad, 12H), 8.11 (s, broad, 12H), 7.44 (m, 24H), 7.04 (s, 3H),
7.00 (m, 24H), 6.99 (s, 12H), 6.85 (d, 6H), 4.3–4.45 (s, broad,
24H), 3.95 (t, 36H), 3.48–3.85 (broad, 24H), 1.8–1.2 (m, broad,
468H), 0.87 (broad, 54H). MS (MALDI-TOF): m/z, calculated
for C555H711N21O63: 8684.96, found 8686.10 [M+]; Elemental
analysis (%) calculated for C555H711N21O63: C 76.76, H 88.25, N
3.39; found: C 76.85, H 88.28, N 3.27.
Materials and methods
All solvents were of analytical grade and purified by using
standard methods.34 1,7-Di(p-t-butyl-phenoxyl)-3,4,9,10-tetra-
carboxylic dianhydried35 and N-(2-aminoethyl)-3,4,5-tris(dode-
cyloxy)benzamide30 were synthesized by the procedures
described previously.
Preparation of dimer 1
Preparation compound 4
To a mixture of compound 3 (142 mg, 0.05 mmol) and 20 mL
CH2Cl2 benzoyl chloride (7 mg, 0.05 mmol) was added dropwise
with continuous stirring at room temperature. The resulted
mixture was stirred continually at room temperature under
a nitrogen atmosphere overnight. After the solvent was evapo-
rated, the residue was purified by column chromatography on
silica gel (CH2Cl2 as eluent) to give dimer 1. 1H NMR (300 MHz,
CDCl3): d ¼ 9.45 (m, 4H), 8.42 (m, 4H), 8.27 (d, 4H), 7.50
(d, 8H), 7.10 (d, 8H), 7.06 (m, 5H), 6.99 (s, 4H), 6.93 (t, 2H), 4.45
(t, 4H), 4.12–4.23 (d, 4H), 3.91 (t, 12H), 3.78 (br, 4H), 1.8–1.2
(m, 160H), 0.87 (m, 18H). MS (MALDI-TOF): m/z, calculated
for C189H241N7O21: 2947.06, found 2948.38 [M+]; Elemental
analysis (%) calculated for C189H241N7O21: C 77.03, H 8.24, N
3.33; found: C 77.25, H 8.32, N 3.12.
To
a
mixture of 1,7-di(p-t-butyl-phenoxyl)-3,4,9,10-tetra-
carboxylic dianhydried (344 mg, 0.5 mmol) in 30 mL dried
pyridine, a solution of N-(2-aminoethyl)-3,4,5-tris(dodecyloxy)
benzamide (165 mg, 0.23 mmol) in 10 mL dried pyridine was
ꢂ
added dropwise. The mixture was refluxed at 115 C for 1.5 h.
After cooling to room temperature, the solvent was evaporated.
The residue was purified by column chromatography on silica gel
(CH2Cl2 as eluent) to give compound 4. (32.5 mg, 10%) 1H NMR
(300 MHz, CDCl3): d ¼ 9.65 (m, 2H), 8.59 (m, 2H), 8.35 (d, 2H),
7.50–7.53 (d, 4H), 7.13 (d, 4H), 6.89 (s, 2H), 6.75 (t, 1H), 4.45
(t, 2H), 3.91 (t, 6H), 3.78 (br, 2H), 1.8–1.2 (m, 78H), 0.87 (m,
9H). MS (MALDI-TOF): m/z, calculated for C89H114N2O11:
1387.91, found 1387.67 [M+]; Elemental analysis (%) calculated
for C89H114N2O11: C 77.02, H 8.28, N 2.02; found: C 77.05,
H 8.46, N 2.12.
Acknowledgements
Financial support from the Natural Science Foundation of
China (21073112, 20871055), the Natural Science Foundation of
Shandong Province (ZR2010EZ007), the Key lab of photo-
chemistry of Chinese Academy of Science, the Ministry of
Preparation compound 3
A mixture of compound 4 (277.5 mg, 0.2 mmol) and imidazole
(1.0 g, 14.68 mmol) in dried toluene (25 mL) was refluxed under
6220 | Soft Matter, 2011, 7, 6213–6221
This journal is ª The Royal Society of Chemistry 2011