title: Efficient White-Light Generation from Ionically Self-Assembled Triply-Fluorescent Organic Nanoparticles.
abstract: Low cost, simple, and environmentally friendly strategies for white-light generation which do not require rare-earth phosphors or other toxic or elementally scare species remain an essentially unmet challenge. Progress in the area of all-organic approaches is highly sought, single molecular systems remaining a particular challenge. Taking inspiration from the designer nature of ionic-liquid chemistry, we now introduce a new strategy toward white-light emission based on the facile generation of nanoparticles comprising three different fluorophores assembled in a well-defined stoichiometry purely through electrostatic interactions. The building blocks consist of the fluorophores aminopyrene, fluorescein, and rhodamine 6G which represent blue, green, and red-emitting species, respectively. Spherical nanoparticles 16(±5) nm in size were prepared which display bright white-light emission with high fluorescence quantum efficiency (26 %) and color coordinate at (0.29, 0.38) which lie in close proximity to pure white light (0.33, 0.33). It is noteworthy that this same fluorophore mixture in free solution yields only blue emission. Density functional theory calculations reveal H-bond and ground-state proton transfer mediated absolute non-parallel orientation of the constituent units which result in frustrated energy transfer, giving rise to emission from the individual centers and concomitant white-light emission.
authors.affiliation: Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata-, 700032, West Bengal, India.
authors.forename: Susmita
authors.initials: S
authors.lastname: Das
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, Kolkata-, 700032, West Bengal, India.
authors.forename: Tanay
authors.initials: T
authors.lastname: Debnath
authors.affiliation: Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata-, 700032, West Bengal, India.
authors.forename: Amrita
authors.initials: A
authors.lastname: Basu
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, Kolkata-, 700032, West Bengal, India.
authors.forename: Deepanwita
authors.initials: D
authors.lastname: Ghosh
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, Kolkata-, 700032, West Bengal, India.
authors.forename: Abhijit Kumar
authors.initials: AK
authors.lastname: Das
authors.affiliation: Department of Chemistry, University of Missouri, Columbia, Missouri, 65211, USA.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Baker
authors.affiliation: Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata-, 700032, West Bengal, India. msap@iacs.res.in.
authors.forename: Amitava
authors.initials: A
authors.lastname: Patra
mesh_terms: D019793:Fluorescein / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D006860:Hydrogen Bonding; D008027:Light; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011522:Protons; D011789:Quantum Theory; D012235:Rhodamines / Q000737:chemistry*; D055672:Static Electricity; D013818:Thermogravimetry
chemical_list: D011522:Protons; D012235:Rhodamines; C026188:rhodamine 6G; D019793:Fluorescein
keywords: energy transfer; nanoparticles; organic salt; proton transfer; white light