title: Surface modification of MnFe₂O₄ nanoparticles to impart intrinsic multiple fluorescence and novel photocatalytic properties.
abstract: The MnFe2O4 nanoparticle has been among the most frequently chosen systems due to its diverse applications in the fields ranging from medical diagnostics to magnetic hyperthermia and site-specific drug delivery. Although numerous efforts have been directed in the synthesis of monodisperse MnFe2O4 nanocrystals, unfortunately, however, studies regarding the tuning of surface property of the synthesized nanocrystals through functionalization are sparse in the existing literature. Herein, we demonstrate the emergence of intrinsic multicolor fluorescence in MnFe2O4 nanoparticles from blue, cyan, and green to red, upon functionalization and further surface modification with a small organic ligand, Na-tartrate. Moreover, we have found an unprecedented photocatalytic property of the functionalized MnFe2O4 nanoparticles in the degradation of a model water contaminant. Detailed characterization through XRD, TEM, and FTIR confirms the very small size and functionalization of MnFe2O4 nanoparticles with a biocompatible ligand. Proper investigation through UV-visible absorption, steady-state and time-resolved photoluminescence study reveals that ligand-to-metal charge-transfer transition from the tartrate ligand to the lowest unoccupied energy level of Mn(2+/3+)or Fe(3+) of the NPs and Jahn-Teller distorted d-d transitions centered over Mn(3+) ions in the NPs play the key role behind the generation of multiple fluorescence from the ligand-functionalized MnFe2O4 nanoparticles. VSM measurements indicates that the superparamagnetic nature of MnFe2O4 nanoparticles remains unchanged even after surface modification. We believe that the developed superparamagnetic, multicolor fluorescent MnFe2O4 nanopaticles would open up new opportunities as well as enhance their beneficial activities toward diverse applications.
authors.affiliation: Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700 098, India.
authors.forename: Monalisa
authors.initials: M
authors.lastname: Pal
authors.forename: Rupali
authors.initials: R
authors.lastname: Rakshit
authors.forename: Kalyan
authors.initials: K
authors.lastname: Mandal
mesh_terms: D002384:Catalysis / Q000528:radiation effects; D005290:Ferric Compounds / Q000737:chemistry*; D005453:Fluorescence; D008027:Light; D008280:Magnetics; D017895:Manganese Compounds / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size
chemical_list: D005290:Ferric Compounds; D017895:Manganese Compounds; C551151:manganese ferrite