Chemistry Reference
In-Depth Information
OC
16
H
33
OC
16
H
33
R
(a)
OC
16
H
33
C
16
H
33
O
C
16
H
33
O
R
C
16
H
33
O
R =
O
O
O
O
OC
2
H
2
OC
2
H
2
NC
OH
HO
(b)
O
O
O
O
O
O
π-conjugated
system
O
O
O
HO
OH
S
S
S
S
π-conjugated system =
O
Figure 7.11
In (a) molecular structures of the OPV derivatives containing an insu-
lated ester group, a conjugated ester, and a cyanoester moiety together
with photographs of the respective gels in n-hexane under illumination at
365 nm. (b) Molecular structure of the phenyl-tetra(thiophene), and
tetra(phenylene) derivatives.
systems. For example, the blue emission of the OPV derivative containing an
insulated ester group located at 466 nm in dichloromethane is red-shifted to
green in the gel state (l
max
¼
530 nm), whereas the green and orange emissions
of the OPV derivatives containing a conjugated ester and a cyanoester moiety,
turned to yellow and red, respectively, in n-hexane gels (Figure 7.11a).
Gelation in nonpolar solvents with oligo(thiophene) or oligo(phenylene)
derivatives attached covalently to dendritic segments has also been shown.
71
The so-called dendron rod-coil molecules containing phenyl-tetra(thiophene)
or tetra(phenylene) segments also showed a fluorescence emission red-shift
upon gellification in a toluene:tetrahydrofuran solution (30:1) (Figure 7.11b).
Indeed, enhanced electronic properties were asserted by these organogelators as
a result of improved p-orbital overlap in the gel state.
