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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.

A one-pot synthesis of extremely stable, water-soluble Cu quantum clusters (QCs) capped with a model protein, bovine serum albumin (BSA), is reported. From matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, we assign the clusters to be composed of Cu 5 and Cu 13 cores. The QCs also show luminescence properties having excitation and emission maxima at 325 and 410 nm, respectively, with a quantum yield of 0.15, which are found to be different from that of protein alone in similar experimental conditions. The quenching of luminescence of the protein-capped Cu QCs in the presence of very low hydrogen peroxide concentration (approximately nanomolar, or less than part-per-billion) reflects the efficacy of the QCs as a potential sensing material in biological environments. Moreover, as-prepared Cu QCs can detect highly toxic Pb 2+ ions in water, even at the part-per-million level, without suffering any interference from other metal ions. � 2011 American Chemical Society.