title: Effect of transannular interaction on the redox-potentials in a series of bicyclic quinones.
abstract: BACKGROUND
  Better understanding of the transannular influence of a substituent on the redox-potentials of bicyclo[2.2.2]octane-derived quinones will help in the design of new compounds with controlled biological activity. However, attempts to directly relate the reduction potentials of substituted triptycene-quinones to the electronic effects of substituents are often unsuccessful.
  
  
  RESULTS
  First and second redox-potentials of a series of bicyclic quinones are compared to computed energies of their LUMO, LUMO+1, and energies of reduction. Transannular influence of substituent on the redox-potentials is rationalized in terms of MO theory. Acetoxy-substituents in the 5,8-positions of the triptycene-quinone system selectively destabilize the product of the two-electron reduction.
  
  
  CONCLUSIONS
  We have shown that first redox-potentials of substituted bicyclic quinones correlate with their calculated LUMO energies and the energies of reduction. The second redox-potentials correlate with calculated LUMO+1 energies. As opposed to the LUMO orbitals, the LUMO+1 orbital coefficients are weighted significantly on the non-quinone part of the bicyclic system. This accounts for: (1) significantly larger substituent effect on the second redox-potentials, than on the first redox-potentials; (2) lack of stability of the product of two electron reduction of 5,8-diacetoxy-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4-dione 5.
authors.affiliation: The University of South Dakota, Department of Chemistry 414 E, Clark St,, Vermillion, SD 57069, USA. gsereda@usd.edu
authors.forename: Grigoriy
authors.initials: G
authors.lastname: Sereda
authors.forename: Jesse
authors.initials: J
authors.lastname: Van Heukelom
authors.forename: Miles
authors.initials: M
authors.lastname: Koppang
authors.forename: Sudha
authors.initials: S
authors.lastname: Ramreddy
authors.forename: Nicole
authors.initials: N
authors.lastname: Collins