Synthesis and physical properties of biquinoxalinyl bridged bis-porphyrins: models for aspects of photosynthetic reaction centres.
The synthesis of biquinoxalinyl-bridged bis-porphyrin 4 and metallated derivatives 5-11 was achieved in high yields. UV-visible spectroscopy and electrochemical experiments indicated weak orbital coupling of the two quinoxalinyl units but minimal orbital coupling between the two porphyrins. The weak electronic communication is attributed to non-planarity, on average, of the molecule because of rotation about the inter-quinoxalinyl connection. This, combined with poor coupling across the fused junctions between the porphyrin and quinoxalinyl units, results in minimal inter-porphyrin communication. As a result, the biquinoxalinyl linkage is appropriate for inclusion in more elaborate synthetic compounds, such as the tris-porphyrin 1, that are designed to model the charge-separation apparatus of Photosynthetic Reaction Centres.
Crossley
Maxwell J
MJ
School of Chemistry, The University of Sydney, NSW 2006, Australia. m.crossley@chem.usyd.edu.au
Sintic
Paul J
PJ
Walton
Robin
R
Reimers
Jeffrey R
JR