Since the conceptual development of the Yin and Yan by the Daoists in ancient China, it is generally understood that most inorganic chemicals consist mainly of anions and cations, which are classified as the yin and yan species, respectively. However, such distinction has been questioned.
In the current study, we would like to present two photochemical systems upon which both inorganic and organic molecules are interacting to the extent it is difficult to distinguish when the organic property ends and inorganic sets in. Philosophically, such systems blends into the harmony which describes the essence of yin and yan.
1) We have synthesised tris-bipyridine ruthenium (II) which is covalently linked to aromatic molecules. Energy and electron transfer between these chromophores determine the photophysical and photochemical properties of these systems. When the chromophores are isoenergetic, however, sharing of the excited electron between them allows the relaxation process to be a co-inhabiting event.
2) We have explored the photoisomerization of 1,4-polybutadiene films for the microlithographic formation of photoactive and electroactive patterns on a micrometer scale. We have found that using a microlithographic mask the cis-isomer can be photoisomerized into its trans-counterpart in a patterned fashion without significant lateral diffusion, and that only the photoisomerized regions are capable of generation of conjugated double bonds upon exposure of the entire polybutadiene film to iodine at room temperature. The selective "I₂-doping" of microlithographically exposed regions thus produces conducting patterns consisting of conjugated trans-1,4- polybutadiene within a non-conducting matrix of iodinated cis-1,4-polybutadiene. Some photophysical and photochemical properties of these films will be presented.

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