Zn Pyro-pheophorbide A-fulleronicotine Dyad; Supramolecular Self Assembled Donor-acceptor System For Photoinduced Charge Separation

摘要

Zn pyro -pheophorbide α and fulleronicotine form in nonpolar solvents a supramolecular self-assembled electron donor-acceptor dyad, which performs fast photoinduced charge separation (0.5 ps) and slow recombination (> 1 ns) as evidenced by photochemical studies.rnChlorophylls (Chl) and bacterial chlorophylls serve with extreme efficiency in light capturing, energy and electron transfer events in primary natural photosynthetic processes. Despite these outstanding properties, utilization of Chls in artificial photoinduced electron transfer systems has been minor in comparison with the vast amount of porphyrins, phthalocyanines and other synthetic aromatic compounds that have been extensively exploited in these systems as covalently and noncovalently linked electron donor-acceptor (D-A) units. Obstacles to the wider utilization of Chls in artificial systems arise chiefly from their rather complicated purification methods, light and chemical sensitivity of unmodified Chls and nontrivial methods for synthetic modification. Moreover, in the symmetrically functionalised chlorin based man-made systems, the asymmetry of the chlorin macrocycle has been a cause of disorder rather than a possible source to construct a structural hierarchy. In photosynthetic antennae, light harvesting complex II, in which Chls are assembled on a protein scaffold, the asymmetry is employed in a side selective ligation of the Chl central metal by imidazole histidine residue.