Design and synthesis of two (pseudo)symmetric giant trichromophoric systems containing the C-60 chromophore

Diels-Alder reaction of C-60 with the 1,3-dienes syn-5 and syn-20 affords t he giant trichromophoric systems syn-C-60-5-DMN-6-P-Zn and syn-C-60-9-DMN-6 -DMA, respectively, in which the three chromphores in each system are Linke d via rigid, hybrid saturated polynorbornane-bicyclo[2.2.0]-hexane ("norbor nylogous") hydrocarbon bridges. The norbornylogous bridge is a strong media tor of electron and energy transfer via a through-bond coupling mechanism. Hence, the giant trichromophores described herein illustrate the necessary methodology for the synthesis of efficient molecular systems that are capab le of generating long-lived charge-separated states. The 1,3-dienes syn-5 a nd syn-20 were prepared in a straightforward manner from two fragments cont aining a diene and a dienophile, and thus a simple building-block approach to such sophisticated systems is described. Semiempirical AM1 MO SCF calcul ations were carried out on the trichromophoric systems to quantify their ab ility to adopt two nondegenerate boat conformations, i.e., extended and fol ded conformers.