1. Dainton Building, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire, S3 7HF, UK
2. School of Pharmacy, University of Reading, Whiteknights, PO Box 224, Reading, Berkshire, RG6 6DX, UK
3. Department of Chemistry and Chemical Technology, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan
4. GEO Specialty Chemicals, Hythe, Southampton, Hampshire SO45 3ZG, UK