12.4 1,8-Naphthalene Monoimide
Another candidate for CPL excimer observation is the 1,8-naphthalene monoimide
core, abbreviated NMI, which usually displays emission maxima in the 450–500 nm
range. There are fewer reported examples of inter- and intramolecular excimer CPL
with NMI and related structures, such as naphthalene bisimide [34]. Below, examples of NMI-based molecules that are able to display CPL allied to intramolecular
excimer situations are described.
As in many of the above examples, it was possible to benefit from a central
binaphthyl core and connect NMI fluorophores. Cheng et al. decorated a binaphthyl
with two naphthalene monoimides (NMI-1 and NMI-2, Fig. 12.8), linked through
chains bearing either 2 or 4 methylenes [35]. Intramolecular excimer allied CPL was
observed in THF solutions (C ¼ 10
À5 M) with g lum of |5.5 Â 10
À3 |–|6.1 Â 10
À3 | for
NMI-1 and |3.0 Â 10
À3 |–|4.1 Â 10
À3 | for NMI-2. Upon addition of water, the
molecules undergo aggregation. Inverted CPL with possible contributions from both
inter- and intramolecular excimers and lower g lum factors were observed. Similarly,
when two NMI moieties were directly linked to a 1,2-diaminocyclohexane scaffold
to obtain NMI-3 and NMI-4 (Fig. 12.8), the resulting derivatives showed excimer
CPL in THF (C ¼ 10
À5 M) with g lum values in the order of |10
À2 | [36]. Again, in
N
H
H
N
N
N
O
O
N
N
N
H
H
N
O
O
N
N
O
O
O
O
O O
O
O
O
O
O
O
M
P
pery-5
pery-6
Kawai 2013
N
N
O
O
O
O
Scheme 12.9 1,2-Diaminocyclohexane/perylene bisimide adducts reported by Kawai et al.
N
N
O
O
O
O
pery-7 Kawai 2007
N
N
O
O
O
O
Scheme 12.10 Binaphthyl/perylene bisimide system
288
F. Zinna et al.