1. a Department of Chemistry , Indian Institute of Technology , Kanpur , 208 016 , India
2. b Laboratory of Chemical Physics , Central Leather Research Institute, Adayaru , Madras , 600 020 , Tamil Nadu , India
3. c Huntington Medical Research Institutes and Department of Chemistry , Magnetic Resonance Spectroscopy Division , 660 S. Fair Oaks, Pasadena , CA , 91123 , USA