| Kannan Muthukumaran1, Lianhe Yu1, Igor Sazanovich2, Eve Hindin2, Christine Kirmaier2, James R. Diers3, David F. Bocian3, Dewey Holten2, and Jonathan S. Lindsey1. (1) Department of Chemistry, North Carolina State University, Raleigh, NC 27696-8204, (2) Department of Chemistry, Washington University, (3) Department of Chemistry, University of California at Riverside |
Efficient new routes are needed to prepare light-harvesting arrays. Bis(dipyrrinato)metal(II) complexes (1) self assemble upon exposure of a metal acetate to the dipyrrin ligand and (2) absorb blue-green light quite strongly e482 nm=105 M-1cm-1. Though first described by Hans Fischer (ca. 1924), such complexes have never been examined as light-harvesting entities, perhaps owing to their very low fluorescent yields. We have developed methodology for the synthesis of porphyrin–dipyrrins. The bis(dipyrrinato)zinc complex alone in toluene has Ff ~ 0.005 and t=95 ps. In the array, the complex has t=1.3 ps, corresponding to an energy-transfer rate of ~(2.6 ps) -1and Ftrans ~97%. Thus, the bis(dipyrrinato)zinc complex provides the joining unit in a self-assembly process and constitutes an effective accessory pigment for a metalloporphyrin.  |