Herein, we report the emergence of multicolor photoluminescence in a mixed-valence manganite nanoparticle La0.67Sr0.33MnO 3 (LSMO NP) achieved through electronic structural modification of the nanoparticles upon functionalization with a biocompatible organic ligand, sodium tartrate. From UV-vis absorption, X-ray photoelectron spectroscopy (XPS), time-resolved photoluminescence study, and Raman spectroscopic measurements, it is revealed that ligand-to-metal charge transfer transitions from highest occupied molecular orbital (HOMO, centered in tartrate ligand) to lowest unoccupied molecular orbital (LUMO, centered in Mn3+/4+ of the NPs), and d-d transitions involving Jahn-Teller sensitive Mn3+ ions in the NPs plays the central role behind the origin of multiple photoluminescence from the ligand functionalized LSMO NPs. © 2012 American Chemical Society.

Pradeep Thalappil

Department Of Chemistry

Robin John

D-D TRANSITIONS

Functionalizations

Functionalized

HIGHEST OCCUPIED MOLECULAR ORBITAL

Jahn-Teller

Ligand-to-metal charge transfers

LOWEST UNOCCUPIED MOLECULAR ORBITAL

MIXED-VALENCE MANGANITE

Organic ligands

Raman spectroscopic

Structural modifications

time-resolved photoluminescence

UV-VIS ABSORPTIONS

Charge transfer

Lanthanum compounds

Ligands

Manganese

Manganese oxide

Nanoparticles

Photoelectrons

Raman spectroscopy

X ray photoelectron spectroscopy

photoluminescence

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Physical Chemistry C

Nanoscale science and nanotechnology are expected to bring about revolutionary advances in the agrochemical industry. Smart delivery of micronutrients enabling sustained release is one such innovative approach to combat the poor nutrient uptake efficiency of conventional micronutrient sources. Herein, we report a bottom-up surface fabrication strategy to modify nanosized zinc oxide (ZnO NPs) surfaces at an atomic scale for sustained release of Zn micronutrients. A large sized environmentally relevant macromolecule humic acid (HA) and a comparatively smaller biologically pertinent citrate ligand were used to functionalize ZnO NPs (30 nm), and the resultant nanohybrids were characterized using electron microscopy, diffraction, and spectroscopic techniques. Functionalization with citrate ligand turns the NP smaller than its original size. The resultant modification in the dissolution characteristics of ZnO NPs leads to sustained release of Zn over a broad pH range. Functionalization with HA causes minimum alteration of NP sizes. But dissolution patterns of NPs examined separately in the presence of HA depicts stabilization of colloidal suspensions. Additionally, picosecond-resolved lifetime measurements reveal efficient photoinduced charge transfer at the nanoheterojunction interfaces. To evaluate the impact of newly developed Zn delivery system on Zn bioavailability, their impacts on the growth of wheat plants (Triticum aestivum) was tested. Results reveal considerable growth enhancements of plants treated with functionalized NPs. The micronutrient nanoformulation requires no auxiliaries and is applicable to plant systems in aqueous dispersions. Our study reinstates the importance of "convergence thinking" or coming together of technologies as a key to creating a fundamental framework toward environmental sustainability. © 2019 American Chemical Society.

ACS Sustainable Chemistry and Engineering

Surface Engineered ZnO-Humic/Citrate Interfaces: Photoinduced Charge Carrier Dynamics and Potential Application for Smart and Sustained Delivery of Zn Micronutrient

We report an unprecedented catalytic decomposition of aqueous bilirubin solution, without any photo-activation, by citrate functionalized Mn 3O4 nanoparticles (NPs). In vitro reactivity of the catalyst on the whole blood specimen of hyperbilirubinemia patients revealed that the catalyst can significantly suppress the total bilirubin level in the blood specimens. © 2014 The Royal Society of Chemistry.

RSC Advances

Unprecedented catalytic activity of Mn 3 O 4 nanoparticles: Potential lead of a sustainable therapeutic agent for hyperbilirubinemia

We have studied the chemical interaction of heavy metal ions such as Hg(II), Hg(I), Pb(II), and Cd(II) of various concentrations with naked and protected silver nanoparticles (Ag@citrate and Ag@MSA, respectively, where MSA is mercaptosuccinic acid). The particles were of 30 and 8 nm diameter, respectively. We observed that the metal ions interact with both the core of the nanoparticles and the functional groups of the capping agents. We study the effects of interaction using spectroscopic and microscopic techniques such as ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and in detail by X-ray photoelectron spectroscopy (XPS). The Hg(II) and Hg(I) ions were reduced to metallic mercury by both of the nanoparticles, because of the feasibility of the redox reaction, whereas no reduction was observed for Cd(II) and Pb(II). The reduction of Hg(I) and Hg(II) ions was due to electrons supplied by the core silver atoms of the nanoparticles, at lower metal ion concentrations. At higher concentrations, the metal ions were chemically bonded to the carboxylate groups of the citrate and MSA. These heavy metal ions form stable sulfides. The presence of different sulfur species, such as oxidized sulfur, disulfides, and metal sulfides, was confirmed by XPS. © 2010 American Chemical Society.

Fulltext

Uptake of toxic metal ions from water by naked and monolayer protected silver nanoparticles: An x-ray photoelectron spectroscopic investigation

A new approach for the synthesis of freely dispersible one-dimensional (1D) lanthanum telluride nanowires (La2Te3 NWs) in the solution phase is reported. The process involves a reaction between tellurium nanowires (Te NWs) and lanthanum nitrate (La(NO3)3) at roomerature. Te NWs act as templates for the formation of La2Te 3 NWs. The aspect ratio of the as prepared La2Te 3 NWs is the same as the parent Te NWs. Various microscopic and spectroscopic tools such as HRTEM, SEM, EDAX, XRD, XPS, Raman, UV?visible, and fluorescence were used for the characterization of the NWs. A new surface enhanced Raman active substrate was synthesized by doping silver in La 2Te3 NWs. Surface enhanced Raman spectra were studied using crystal violet (CV) as the analyte. Raman features have been observed up to a concentration of 10?8 M of CV. Different concentrations of Ag in Ag-doped La2Te3 NWs were investigated. The monodispersity, homogeneity, and Raman enhancement properties of the NWs, synthesized through a simple solution phase protocol, are expected to motivate further studies on this material. © 2010 American Chemical Society.

Lanthanum telluride nanowires: Formation, doping, and Raman studies

Journal of the American Chemical Society

Mechanisms of pH-Dependent Activity for Water Oxidation to Molecular Oxygen by MnO2 Electrocatalysts

Nature Nanotechnology

A multifunctional core–shell nanoparticle for dendritic cell-based cancer immunotherapy

J. Mater. Chem.

Dual imaging probes for magnetic resonance imaging and fluorescence microscopy based on perovskite manganite nanoparticles

Emergence of multicolor photoluminescence in La0.67Sr 0.33MnO3 nanoparticles

Journal	Journal of Physical Chemistry C
ISSN	19327447
Open Access	No