Design and synthesis of two (pseudo)symmetric giant trichromophoric systems containing the C60 chromophore

Diels-Alder reaction of C-60 with the 1,3-dienes syn-5 and syn-20 affords the 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 Linked via rigid, hybrid saturated polynorbornane-bicyclo[2.2.0]-hexane ("norbornylogous") hydrocarbon bridges. The norbornylogous bridge is a strong mediator 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 capable of generating long-lived charge-separated states. The 1,3-dienes syn-5 and syn-20 were prepared in a straightforward manner from two fragments containing a diene and a dienophile, and thus a simple building-block approach to such sophisticated systems is described. Semiempirical AM1 MO SCF calculations were carried out on the trichromophoric systems to quantify their ability to adopt two nondegenerate boat conformations, i.e., extended and folded conformers.