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Surface Modification of MnFe2O4 Nanoparticles to Impart Intrinsic Multiple Fluorescence and Novel Photocatalytic Properties
journal contribution
posted on 2014-04-09, 00:00 authored by Monalisa Pal, Rupali Rakshit, Kalyan MandalThe 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 Mn2+/3+or Fe3+ of
the NPs and Jahn–Teller distorted d–d transitions centered
over Mn3+ 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.