1. Department of Chemistry, University of Ruhuna, Matara, Sri Lanka, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5a Pawińskiego, 02-106 Warsaw, Poland, National Research and Development Institute of Isotopic and Molecular Technologies, P. O. Box 700, R-400293 Cluj-Napoca 5, Romania, and Department of Physical Chemistry/Biophysical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6525 ED, Nijmegen, The Netherlands