Photochromic Systems for Molecular Logic and Photo-Switching of Biological Processes

by Prof. Joakim Andréasson (Dept. of Physical Chemistry, CTH)

Thursday 24 Apr 2008, 09:15 → 10:00 Europe/Stockholm

FA32

Photochromic molecules, or photochromes, have been covalently linked to other organic molecules to constitute dyads, triads, etc. The key operation of these constructs is the photoinduced isomerization of the photochromes between the two thermally stable forms. Upon isomerization, properties such as excitation energies, redox properties, electric dipole moment, structure etc., experience substantial changes. These changes can be harnessed to switch “on” or “off” a given functionality of the molecule, e.g., energy and electron transfer reactions. The spectral changes (absorption and emission) that occur upon switching can be read optically and used as “output signals”. Using this approach, molecules capable of performing the function of several Boolean logic gates were designed. These systems were further developed to perform as more complex logic devices such as half-adders, multiplexers, demultiplexers, and encoders or decoders. Furthermore, it has recently been shown that photochromic monomers can be used to photo-switch the action of biological processes, e.g., DNA-binding and membrane penetration. A selection of optically controlled molecular logic devices will be presented together with new results from the studies on biological systems.