Azagarsamy et al.
JOCArticle
Hz, 2H), 2.15-2.13 (m, 2H) 1.92 (bs, 1H), 1.80-1.20 (m, 159H),
0.90-0.83 (m, 18H); 13C NMR (100 MHz, CDCl3) δ 168.0,
167.8, 160.5, 160.4, 160.2, 159.1, 157.4, 156.1, 147.0, 141.9,
139.7, 139.6, 137.9, 137.8, 135.8, 135.7, 120.4, 119.7, 119.7,
119.3, 110.2, 107.0, 105.7, 105.6, 105.4, 104.8, 104.4, 104.2,
103.5, 101.2, 101.0, 98.2, 82.3, 82.3, 82.1, 82.0, 82.0, 81.1, 70.2,
69.9, 69.0, 68.9, 68.9, 68.1, 66.9, 66.3, 66.2, 65.8, 65.4, 50.0, 32.0,
29.6, 29.4, 29.3, 29.2, 28.1, 26.1, 22.7, 22.0, 14.2; MALDI-TOF
m/z 3143.1 (C185H263FeN3O35 requires 3144.9).
NMR (300 MHz, CDCl3) δ 7.00 (s, 1H), 6.78-6.39 (m, 27H),
5.08 (s, 2H), 5.00-4.91 (m, 12H), 4.68 (s, 2H), 4.49-4.41
(m, 14H), 4.19-4.08 (m, 9H), 3.95-3.85 (m, 14H), 2.65-2.58
(m, 2H), 1.97-1.15 (m, 163H), 0.90-0.78 (m, 18H); 13C NMR
(75 MHz, CDCl3) δ 167.9, 167.9, 167.8, 167.8, 167.7, 160.3,
160.3, 159.0, 159.0, 158.9, 157.3, 157.2, 156.8, 155.9, 146.6,
141.9, 139.4, 139.3, 137.9, 137.6, 135.7, 135.6, 135.4, 120.6
119.5, 119.5, 119.0, 110.1, 110.0, 106.9, 105.7, 105.5, 105.3,
105.2, 104.6, 104.3, 103.3, 101.1, 100.8, 100.8, 82.2, 82.2,
81.9, 81.9, 70.0, 69.7, 68.7, 68.0, 67.9, 67.2, 66.1, 66.0, 65.6,
65.2, 31.7, 29.4, 29.4, 29.2, 29.2, 29.1, 29.0, 28.4, 27.9, 25.9, 25.8,
22.7, 22.5, 21.5, 14.0; MALDI-TOF m/z 3143.6, 3166.5
Synthesis of G3(L4)Fc. According to the general procedure
for click reaction, G3(L4) (0.07 g, 0.011 mmol) was reacted with
azidomethyl ferrocene (8.0 equiv) to yield 0.6 g (83%) of G3-
(L4)Fc. 1H NMR (400 MHz, CDCl3) δ 7.21 (s, 1H), 6.79-6.43
(m, 59H), 5.25 (s, 2H), 5.03-4.95 (m, 28H), 4.70-4.69 (m, 2H),
4.50-4.46 (m, 30H), 4.26 (s, 2H), 4.20-4.17 (m, 7H), 3.97-3.90
(m, 30H), 2.86 (t, J = 7.2 Hz, 2H), 2.15-2.13 (m, 2H) 1.80-1.15
(m, 359H), 0.90-0.83 (m, 42H); 13C NMR (100 MHz, CDCl3) δ
168.0, 168.0, 167.9, 167.9, 160.5, 160.2, 159.2, 159.1, 157.4,
156.1, 147.0, 141.9, 139.6, 137.9, 137.8, 135.8, 135.6, 120.3,
119.8, 119.3, 110.2, 107.0, 105.8, 104.6, 101.2, 101.0, 82.3,
82.1, 82.0, 82.0, 82.0, 81.1, 70.2, 69.9, 69.0, 68.9, 68.9, 68.1,
66.9, 66.3, 66.2, 65.7, 65.5, 49.9, 32.1, 31.9, 29.6, 29.6, 29.4, 29.3,
29.3, 29.2, 29.1, 28.8, 28.1, 26.1, 22.7, 22.2, 14.0; MALDI-TOF
m/z 6610.9 (C393H567FeN3O75 þ Naþ requires 6612.5).
(C185H263FeN3O35 requires 3144.9 and C185H263FeN3O35
þ
Naþ requires 3167.9).
Synthesis of G3(L2)Fc. According to the general procedure
for the formation of triazole, G3(L2) (0.1 g, 0.01 mmol) was
reacted with azidomethyl ferrocene to yield 0.08 g (80%) G3-
(L2)Fc. 1H NMR (300 MHz, CDCl3) δ 7.05 (s, 1H), 6.81-6.40
(m, 59H), 5.12-4.90 (m, 30H), 4.68 (s, 2H), 4.52-4.42 (m, 30H),
4.16-4.07 (m, 9H), 3.98-3.88 (m, 30H), 2.71-2.68 (m, 2H),
2.05-1.15 (m, 361H), 0.86-0.74 (m, 42H); 13C NMR (75 MHz,
CDCl3) δ 167.9, 167.8, 160.3, 159.0, 158.9, 157.3, 156.9, 155.9,
146.6, 141.9, 139.4, 138.0, 137.7, 137.6, 137.5, 135.7, 135.6,
135.4, 120.4, 119.6, 119.0, 110.0, 106.9, 105.6, 105.3, 104.6,
104.4, 103.2, 101.0, 100.8, 82.2, 81.9, 81.9, 81.1, 70.0, 69.7,
68.7, 68.4, 67.9, 67.3, 66.1, 65.6, 65.2, 60.5, 31.7, 29.4, 29.2,
29.2, 29.1, 29.0, 28.5, 27.9, 25.9, 22.5, 14.0; MALDI-TOF m/z
6612.8, 6588.8 (C393H567FeN3O75 þ Naþ requires 6612.5 and
Synthesis of G1(L1)Fc. The alcohol G1(L1) (0.09 g, 0.08
mmol) was subjected to click reaction as per the general proce-
dure to yield 0.10 g (85%) of G1(L1)Fc. H NMR (400 MHz,
1
CDCl3) δ 7.02 (bs, 1H), 6.70-6.39 (m, 11H), 5.08 (bs, 2H), 4.91
(s, 4H), 4.62 (s, 2H), 4.50-4.4 (m, 6H), 4.20-4.09 (m, 9H), 3.88
(t, J = 5.6 Hz, 6H), 2.63 (bs, 2H), 2.42 (bs, 1H), 1.97 (bs, 2H),
1.75-1.70 (m, 4H), 1.50- 1.19 (m, 55H), 0.88-0.84 (t, J = 6.8
Hz, 6H); 13C NMR (100 MHz, CDCl3) δ 167.9, 167.7, 160.3,
159.0, 159.0, 156.9, 155.8, 146.6, 142.1, 139.4, 135.7, 120.7,
118.9, 110.1, 106.8, 105.3, 104.7, 103.3, 101.0, 100.7, 82.1,
81.8, 69.7, 69.1, 67.9, 67.1, 66.0, 65.5, 65.0, 49.6, 31.7, 29.4,
29.4, 29.2, 29.1, 29.0, 28.3, 27.9, 25.8, 22.5, 21.5, 14.0; MALDI-
TOF m/z 1423.3 and 1446.4 (C81H111FeN3O15 requires 1422.6
and C81H111FeN3O15 þ Naþ requires 1446.6).
C
393H567FeN3O75 requires 6589.5).
Synthesis of G3(L3)Fc. According to the general procedure
for click reaction, G3(L3) (0.11 g, 0.018 mmol) was reacted with
1
azidomethyl ferrocene to yield 0.08 g (74%) of G3(L3)Fc. H
NMR (300 MHz, CDCl3) δ 7.01 (s, 1H), 6.79- 6.40 (m, 59H),
5.10 (s, 2H), 5.02-4.88 (m, 28H), 4.68 (s, 2H), 4.50-4.41 (m,
30H), 4.25-4.05 (m, 9H), 3.97-3.84 (m, 30H), 2.68-2.62 (m,
2H), 2.00-1.90 (m, 361H), 0.90-0.75 (m, 42H); 13C NMR (75
MHz, CDCl3) δ 167.9, 167.8, 167.8, 167.7, 160.3, 159.0, 159.0,
158.9, 157.2, 156.9, 155.9, 146.6, 141.8, 139.4, 139.3, 137.8,
137.6, 135.7, 135.6, 135.4, 120.6, 119.6, 119.5, 119.0, 110.0,
106.9, 105.6, 105.2, 104.6, 101.0, 100.8, 82.2, 81.9, 81.2, 70.0,
69.7, 68.7, 67.9, 66.1, 65.6, 31.7, 29.4, 29.4, 29.2, 29.2, 29.1, 29.0,
28.4, 27.9, 25.9, 22.5, 22.5, 14.0; MALDI-TOF m/z 6588.3
(C393H567FeN3O75 requires 6589.5).
Synthesis of G2(L1)Fc. According to the general procedure
for click reaction, G2(L1) (0.3 g, 0.10 mmol) was reacted with
azidomethyl ferrocene to yield 0.31 g (96%) of G2(L1)Fc. H
1
NMR (400 MHz, CDCl3) δ 7.06 (bs, 1H), 6.75-6.35 (m, 27H),
5.12 (s, 2H), 5.00-4.92 (m, 12H), 4.65 (s, 2H), 4.50-4.41 (m,
14H), 4.18-4.08 (m, 9H), 3.92-3.85 (m, 14H), 2.68 (bs, 2H),
2.01-1.10 (m, 163H), 0.90-0.81 (m, 18H); 13C NMR (100
MHz, CDCl3) δ 167.9, 167.8, 160.3, 159.0, 159.0, 157.3, 155.9,
139.4, 137.6, 135.4, 119.6, 110.1, 106.9, 105.6, 105.3, 104.4,
101.1, 100.8, 82.2, 82.0, 81.9, 70.1, 69.8, 68.7, 68.0, 66.2, 65.6,
31.8, 29.5, 29.4, 29.3, 29.2, 29.1, 29.0, 27.9, 25.9, 22.6, 14.0;
MALDI-TOF m/z 3168.5, 3145.6 (C185H263FeN3O35 þ Naþ
requires 3167.9 and C185H263FeN3O35 requires 3144.9).
Synthesis of G3(L1)Fc. As per the general procedure for click
reaction, G3(L1) (0.14 g, 0.02 mmol) was reacted with azido-
methyl ferrocene to yield 0.12 g (80%) of G3(L1)Fc. 1H NMR
(300 MHz, CDCl3) δ 7.08 (s, 1H), 6.80-6.40 (m, 59H), 5.13 (s,
2H), 5.02-4.92 (m, 28H), 4.66 (s, 2H), 4.52-4.42 (m, 30H),
4.22-4.08 (m, 9H), 3.97-3.88 (m, 30H), 2.74-2.68 (m, 2H),
2.08-1.09 (m, 361H), 0.90-0.81 (m, 42H); 13C NMR (75 MHz,
CDCl3) δ 167.9, 167.9, 167.8, 160.3, 159.0, 159.0, 158.9, 157.3,
157.0, 155.9, 146.6, 142.0, 139.4, 137.7, 137.6, 135.8, 135.6,
135.4, 120.4, 119.6, 119.5, 119.0, 110.0, 106.9, 105.6, 105.2,
104.7, 104.4, 103.4, 101.1, 100.8, 82.2, 82.0, 81.9, 81.9, 81.2,
70.1, 69.7, 68.8, 67.9, 67.3, 66.1, 66.0, 65.6, 65.1, 49.6, 31.7, 29.4,
29.2, 29.2, 29.1, 29.0, 28.5, 28.1, 27.9, 25.9, 22.5, 14.0; MALDI-
TOF m/z 6587.0 (C393H567FeN3O75 requires 6589.5).
Conclusion
Differential encapsulation of active functionalities in den-
drimers has been previously studied in the context of gen-
eration dependence. Very little attention has been paid to the
differences in the encapsulation of functional groups within
different layers of dendrimers. We have designed, synthe-
sized, and studied electroactive dendrons to investigate the
possible variations. In our studies, we have shown the
following: (1) We could obtain dendrons where an electro-
active functionality can be incorporated at specific locations
in dendrons. We have utilized the dendrimer sequencing
methods and the versatile 1,3-dipolar cycloaddition (click
reaction) to incorporate the electroactive moiety at different
layers. This chemistry also provides an opportunity to
incorporate any desired functionality at a precise location
in dendrimers. (2) Whereas the redox potential of ferrocene
did not vary with generation, the E1/2 values were signifi-
cantly different in the intermediate layers at higher genera-
tion dendrons. These results suggest that the micro-
environment of the intermediate layers is dictated by the
dendron, while those of the periphery and the core is similar
Synthesis of G2(L2)Fc. According to the general procedure
for the formation of triazole, G2(L2) (0.12 g, 0.04 mmol) was
subjected to click reaction to yield 0.10 g (75%) of G2(L2)Fc. 1H
9484 J. Org. Chem. Vol. 74, No. 24, 2009