2008 Eighth Annual Beckman Scholars Symposium
Saturday Poster Session - July 29, 2006

The electronic coupling element (HDA) can be determined from the full-width half maximum and molar absorptivity of the intervalence charge transfer band in the near infrared (NIR). To distinguish this band from other electronic transitions, the electronic transitions of metalloporphyrin monomers were measured experimentally. A series of ruthenium (II) porphyrin monomers were synthesized photolytically and characterized by UV/VIS spectroscopy. The spectra of the neutral and cationic species were then measured in the NIR. Pyrizine capped octaethylporphyrins and tetraphenylporphyrins exhibited no NIR transitions, whereas pyridine capped monomers exhibited NIR transitions at approximately 5000 and 7000 cm-1. These observations confirm the hypothesis that both the axial and equatorial substituents have a significant effect on the electronic properties of the metal, which may be useful in tuning the coupling element of oligomers. The experimental data was compared to theoretical predictions as a means of calibration in the efforts to design a theoretical program capable of accurately calculating coupling elements of large systems.