<div>
<p>Cyclocurcumin is a natural compound
extracted from turmeric and showing, in addition to antiinfective, antibacterial, and
intinflammatory capabilities, solvent-dependent phtoswitching ability. The
solvent-dependent photochemistry of cyclocurcumin has been rationalized on the
basis of a competition between π-π* and n-π* states. Recently we
have reported the synthesis of a biomimetic analogue showing enhanced
photochemical properties and in particular presenting photoswitching capacity
in various media. In the present contribution we rely on the use of molecular
modeling and simulation, incuding density functional and wavefunction based
methods to explore the excited states potential energy surface landscape. We
see that the addition of a carbon-carbon double bond to the core of the natural
compounds favors the population of the π-π* state, whatever the choice of the
solvent, and hence leads to photoisomerisation, with fluorescence reduced to
only a minor channel, rationalizing the experimental observations. In addition,
the two photon absorption cross section is also strongly increased compared to
the parent compound, paving the way to the use in biologically oriented
applications.</p></div>
Experimental and computational data on two-photon absorption and spectral deconvolution of the upper excited states of dye IR780
