Molecular photoinduced long-range electron

Harpoon mechanism Reaction sequence (thermal or photoinduced) between neutral molecular or atomic entities in which long-range electron transfer is followed by a considerable reduction of the distance between donor and acceptor sites as a result of the electrostatic attraction in the ion pair created. 

The photochemistry is based on polypyridyl complexes of Ru, Os and Re. They have well-defined excited states for which photoinduced electron and energy transfer are well documented processes. 3 These processes continue to occur when the complexes are inco orated into soluble polymers or derivatized peptides. This fact and the molecular architecture offered by polymers and peptides has provided the basis for our studies on long-range electron and energy transfo. ... 

Monolayer systems are characterized by a very limited molecular mobility and high degree of order. Photoinduced electron transfer processes have been investigated in these systems in order to evaluate the influence of energy delocalization on the quantum efficiency of the electron transfer step and the range of long distance electron transfer. 

In making rotaxanes usable as parts of molecular devices and with the purpose of studying long range election transfer processes within large molecular systems of well controlled geometries, the introduction of photoactive and electroactive compounds has been a valuable development. Photoinduced electron transfer between porphyrin species has a particular relevance to the primary events occurring in bacterial photosynthetic reaction center complexes, and so is a well studied phenomenon. 

A doubly metallated 15 base-pair double helix containing ruthenium and rhodium at each end of the strands [106] showed the efficiency of DNA for coupling electron donors and acceptors over a very long range, greater than 40 A. The DNA double helix was found to behave like a piece of molecular wire with fast electron-transfer rates (>1010 s l) for the photoinduced electron transfer between the metallointercalators [107-109] and semiempirical Hartree-Fock calculations of HAB for DNA mediated electron transfer [110] were described. 

Long-range photoinduced electron and energy transfer are being explored in molecular assemblies of soluble polymers and peptides. 

---