1. Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom, Free Radical Research Facility, Daresbury Laboratory, Daresbury, Warrington WA4 4AD, United Kingdom, School of Physical and Geographical Sciences, Keele University, Keele ST5 5BG, United Kingdom, and Biosciences Research Institute, University of Salford, Salford M5 4WT, United Kingdom