trans-isomer of 1-[10-(4-phenyl-azophenixy)decyl]pyridinium
bromide (namely,AzoC10) can be well recognized bya-CD, due
to favorable hydrophobic and van der Waals interactions. Upon
UV irradiation at 365 nm, thetrans-diazobenzene moiety under-
goes the well-known photoisomerization process to thecisform
with subsequent disassembling. This is due to the increased ste-
ric demand because of the change in conformation of the
azobenzene moiety, within the hydrophobic cavity of thea-CD.
Using the same hydrophobic supramolecular interactions, it is
possible to create assemblies based on luminescent metal
complexes which, if judiciously chosen, can lead to new pro-
perties not present in the simple components such as vectorial
photoinduced processes.
Br- Br
N.N. O N NN O N
UV lightVisible lightFIG. 2. Schematic light-induced assembly and disassembly process.
Reproduced with the permission of Wiley-VCH ( 41 ).
FIG. 1. Schematic representation of some host systems used for
host–guest assemblies: from left: calixarene, cucurbituril, and
b-cyclodextrine.
PHOTOPHYSICS OF MOLECULAR ASSEMBLIES 55