1. Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata 700 032, India
2. Department of Chemistry, Presidency University, 86/1 College Street, Kolkata 700 073, India
3. Departament de Quimica
Inorgànica i Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain