A new family of photochromic molecules (the diarylethene) has been recently
developed with excellent optical, termo-chemical and fatigue resistance
properties.
These materials become strong candidate for optical data storage and/or
other electronic molecular device. Generally these materials are blended
with a polymer matrix.
One of the problems with these molecules, still unsolved, is the interaction
with the polymer matrix. To solve this problem for the first time a polymer
has been synthesized whose repeating unit belongs to the family of diarylethenes.
In this way the polymers can be cast as thin film and no blending with
a host matrix is required.
The photochromic properties of the polymer are surprisingly better
then those of the monomer, its cyclization quantum yield is very high for
a photochromic compound being more then twice that of the monomer and is
the highest one in the diarylethene family (0.85).
A very important additional property is that the polymer in the conjugated
form can be doped with an anodic potential 0.6 V vs. Ag/Ag+,
thus opening the field of photoswitchable electronic applications. The
optical spectra during cyclisation and opening show a very stable isosbestic
point.
The maximum conversion rate (at 313 nm) reachable at the photostationary
state is larger then 99%. Vibrational spectra have been investigated and
interpreted on the basis of molecular dynamical calculations combined with
ab initio calculations (when possible).