[1] Guru Nanak Dev Univ, Dept Chem, Amritsar 143005, Punjab, India
[2] Univ Witwatersrand, Sch Mol & Cell Biol, Private Bag 3, ZA-2050 Johannesburg, South Africa
[3] Univ KwaZulu Natal, Sch Chem & Phys, P Bag X54001, ZA-4000 Durban, South Africa
[4] Khalsa Coll, Dept Chem, Amritsar 143005, Punjab, India