1. Contribution from the Departments of Organic Chemistry and Biochemistry and of Chemistry and INSTM, University of Naples Federico II, Via Cintia, I-80126 Naples, Italy, and Lennard-Jones Laboratories, School of Physical & Geographical Sciences, Keele University, Staffordshire ST5 5BG, Free Radical Research Facility, Daresbury Laboratory, Warrington, Cheshire WA4 4AD, and BioSciences Research Institute, University of Salford, Salford M5 4WT, United Kingdom