1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, Jilin, P. R. China
2. Department of Chemistry, University of Liverpool, Liverpool L69 3BX, U.K.
3. Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, via A. Moro 2, Siena 53100, Italy