1. Bio-organic Research Laboratory University of Delhi; Delhi -110 007 India
2. Department of Chemistry; University of Delhi; Delhi 110 007 India
3. CSIR-National Physical Laboratory; Dr. K. S. Krishnan Road New Delhi 110 012 India
4. PG & Research Department of Physics; Aringer Anna Government Arts College; Musiri 621 211 India
5. Department of Chemistry, Sri Venkateswara College; University of Delhi; New Delhi 110021 India