Biomedical Engineering Reference
In-Depth Information
Triphenylene-based two component organogel
27
composed of
2,3,6,7,10,11-hexakis(N,N-dimethylaminopropylaminocarbonylmethoxy)
triphenylene and 4'-dodecyloxybiphenyl-4-carboxylic acid has been syn-
thesized by Tao
et al.
(Figure 9.11) [73]. h e aggregation process involved
multiple interactions, including ionic bond, hydrogen bonds, π-π interac-
tion, etc., mainly in aromatic solvents like benzene, toluene, xylene, etc.
h e nanoi bers formed have a diameter of 50-130 nm which further led
to the formation of three-dimensional networks. However, no mesophase
formation was found in this material.
9.3.1.2.2 Unsymmetrical Monosubstituted Ionic Triphenylenes
Imidazolium-based ionic liquid crystals
29a-b (X=O)
have been prepared
by attaching ω-brominated triphenylene covalently with 1-methylimid-
azole, as shown in Figure 9.12 [74]. h ese molecules show Col phase over a
wide temperature range (Table 9.3). h e iodide salt exhibited slightly lower
isotropic temperature than the bromide salt. Non-ionic imidazole substi-
tuted triphenylene derivative did not show any liquid crystalline behavior.
Probably, ionic self-assembly is essential for mesophase formation.
Similar triphenylene derivatives with ester linkage instead of ether link-
age
29c-e (X= -COO)
have been reported by Cui and Zhu [75]. h ese com-
pounds were prepared via esterii cation of hydroxypentakis(pentyloxy)
triphenylene with ω-bromoacylchloride. Quaternary imidazole salts were
prepared by substitution of Br atom with 1-methylimidazole (Figure 9.12).
O
C
OC
5
H
11
OR
NH O
3
S
CH
3
O
O
N
n
Br
OR
OC
5
H
11
OC
5
H
11
OR
OC
5
H
11
RO
OR
OC
5
H
11
30
31a-e
OC
5
H
11
OR
OR
Me
2
N
Me
2
N
O
OH
X
N
N
Y
-
NH
C
5
H
11
O
n
OR
RO
RO
Cl
-
(i),
(vi)
(v)
(i) /
(
iii
)
N
OR
N
C
5
H
11
O
OC
5
H
11
RO
OR
OR
OR
OC
5
H
11
32a-f
28
29a-e
Figure 9.12
Synthesis of unsymmetrical monosubstituted ionic triphenylenes (i) alkyl
bromide, K
2
CO
3
, 2-butanone, rel ux; (ii) pyridine, toluene; (iii) ω-bromoacyl chloride,
THF, pyridine; (iv) Py-3-COCl, CH
3
SO
3
H; (v) NaN
3
, DMF and LiAlH
4
, THF; (vi)
guanidinium chloride, NaOH, NEt
3
, DCM, rel ux.
