Phenylazomethine Dendrimers Possessing Unique Nanoscaled Electron Gradients
K. Yamamoto, M. Higuchi, S. Shiki, M. Tsuruta, & H. Chiba
Kanagawa Academy of Science & Technology, and Department of Chemistry, Faculty of Science &
Technology, Keio University, Yokohama 223-8522, Japan
Supporting Information
784, 695; MALDI-TOF-MS calcd 2659.12 [M]+,
found 2659.56.
TEM Measurement. The chloroform solution
Atomic absorption spectroscopy (AAS). The
Sn content in the DPA G4 fully complexed with
SnCl2 was determined to be 31.0% by atomic
absorption spectroscopy (AAS). The theoretical
value of the Sn content in a DPA G4 molecule
complexed with 30 SnCl2 molecules is
calculated to be 31.96%. Therefore, at least 29
molecules of SnCl2 are complexed to a DPA G4
molecule.
N
N
N
N
N
F
N
IR Measurement. The IR spectra of DPA G1-4
complexed with SnCl2 support the coordination
of SnCl2 to the imine sites. The absorption
attributed to the stretching vibration of the imine
bond (1617 cm-1) of DPA G4 was shifted to
1624 cm-1 by the complexation with SnCl2. The
similar shift was also observed in DPA G1-3.
N
F
N
N
Synthesis of DPA-F G3: DPA G3 dendron (4.01
g, 3.19 mmol), tetrafuloro-p-phenylenediamine
(287 mg, 1.59 mmol), and DABCO (1.07 g, 9.57
mmol) were dissolved in chlorobenzene (200
mL). Titanium(IV) tetrachloride (98.3 mg, 2.39
mmol) was added dropwisely. The addition
funnel was rinsed with chlorobenzene (5 mL).
The reaction mixture was heated in an oil bath at
125 °C for 24 h. The precipitate was removed by
filtration. The filtrate was concentrated, DPA-F
G3 (112mg, 0.0421mmol, 3%) was isolated by
silica gel column chromatography (ethyl
acetate:hexane:dichloromethane = 1:5:2 - 1:3:1,
Rf = 0.27 in the solution of ethyl
acetate:hexane:dichloromethane
=
1:3:1).
DPA-F G3: 19F NMR (376 MHz, CDCl3, 30 °C,
ppm)  -149.20 (s, 4F); 1H NMR (400 MHz,
CDCl3, TMS standard, 30 °C, ppm)  7.78-6.49
(m, 128H); 13C NMR (100 MHz, CDCL3, TMS
standard, 30 °C, ppm)  174.55, 169.00, 168.63,
168.39, 168.22, 168.12, 167.58, 154.77, 153.71,
153.53, 152.51, 152.04, 151.92, 139.22, 139.18,
139.00, 138.93, 135.70, 135.56, 135.34, 134.17,
134.08, 132.52, 132.29, 130.78, 130.66, 130.33,
130.08, 129.97, 129.32, 129.15, 128.77, 128.68,
128.56, 128.11, 128.02, 127.96, 127.81, 127.67,
120.97, 120.69, 120.48, 120.28, 120.21, 119.99;
IR (KBr, cm-1) 1617 (C=N), 1579 (phenyl), 847,
F
N
N
N
F
N
N
DPA-F G3
(0.2 mg/mL) of DPA G4 complexed with 14 or
30 equivalents of SnCl2 was deposited on
carbon-coated copper grids, and the grids were
inverted on RuO4 vapor. The TEM images were
obtained at 120 kV with a JEOL JEM-2010 at a
magnification of 300000x and 1200000x. The
images was enlarged four times and printed,
then scanned into the computer, and analyzed
with TIFF image.
Shell-selective reduction of imines in the
metallodendrimers. The typical procedure is as
follows. To the dichloromethane/acetonitrile
(2:1) solution (60 mL) of DPA G2 (20 mg, 1.7 x
10-5 mol) and SnCl2 (6.6 mg, 3.4 x 10-5 mol), the
acetonitrile solution (20 mL) of NaBH4 (7.4 mg,
2.0 x 10-4 mol) was added. The reaction mixture
was stirred at room temperature for 30 min.
After the reaction, the crude mixture was
washed with water including 5% triethylamine,
and the organic layer was dried using Na2SO4.
The DPA G2 with the reduced imines of the first
shell was obtained in an 80% yield by silica gel
column chromatography, and identified by 1H
NMR and MS spectral measurements. The yield
was determined using NMR.
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