Graphene oxide intercalation into self-assembled porphyrin J-aggregates

Studies are undertaken to examine graphene oxide intercalation into self-assembled J-aggregate porphyrin structures. Fluorescence lifetime and fluorescence anisotropy imaging were applied along with scanning electron microscopy to study the structure and optical properties of a graphene oxide/TMPyP hybrid composite material. It was seen that the presence of graphene oxide alters the macroscale and nanoscale self-assembled structures of TMPyP in addition graphene oxide also alters the optical activity reducing the emission intensity and exciton recombination lifetime. Evidence exists to support a model where planer-symmetric graphene oxide and TMPyP co-operate in the formation of self-assembled macro and nanostructures forming a composite with strong graphene oxide/TMPyP interaction

Graphene oxide intercalation into self-assembled porphyrin J-aggregates

Studies are undertaken to examine graphene oxide intercalation into self-assembled J-aggregate porphyrin structures. Fluorescence lifetime and fluorescence anisotropy imaging were applied along with scanning electron microscopy to study the structure and optical properties of a graphene oxide/TMPyP hybrid composite material. It was seen that the presence of graphene oxide alters the macroscale and nanoscale self-assembled structures of TMPyP in addition graphene oxide also alters the optical activity reducing the emission intensity and exciton recombination lifetime. Evidence exists to support a model where planer-symmetric graphene oxide and TMPyP co-operate in the formation of self-assembled macro and nanostructures forming a composite with strong graphene oxide/TMPyP interaction

Thermal and aqueous stability improvement of graphene oxide enhanced diphenylalanine nanocomposites

Nanocomposites of diphenylalanine (FF) and carbon based materials provide an opportunity to overcome drawbacks associated with using FF micro- and nanostructures in nanobiotechnology applications, in particular, their poor structural stability in liquid solutions. In this study, FF/graphene oxide (GO) composites were found to self-assemble into layered micro- and nanostructures, which exhibited improved thermal and aqueous stability. Dependent on the FF/GO ratio, the solubility of these structures was reduced to 35.65% after 30 min as compared to 92.4% for pure FF samples. Such functional nanocomposites may extend the use of FF structures to, e.g., biosensing, electrochemical, electromechanical or electronic applications.European Commission - European Regional Development FundEuropean Commission - Seventh Framework Programme (FP7)Science Foundation IrelandProgramme for Research in Third Level Institutions (PRTLI) Cycle 5Russian Foundation for Fundamental ResearchCICECO-Aveiro Institute of MaterialsFCT/MECPT2020 Partnership Agreemen

Dependence of Eu3+ photoluminescence properties on structural transformations in diopside-based glass-ceramics

Herein, diopside based glass-ceramics (GCs) were produced by sintering of glass powder compacts at 850 °C for 300 h. A special attention was paid on understanding the influence of structural transformations upon substituting strontium for calcium on the Eu3+ emission behavior. X-ray diffraction and Raman spectra showed the formation of diopside (CaMgSi2O6) in Sr-free glasses. Introduction of Sr led to the appearance of Sr-akermanite (Sr2MgSi2O7), whose formation increased continuously with increasing Sr/Ca ratio. The photoluminescence spectra exhibited intense 5D0 →7Fj transitions of Eu3+ ions. The intensity parameters (Ω2 and Ω4) and the Eu–O ligand behavior were determined using the Judd-Ofelt (JO) theory from the emission spectra as a function of various Sr concentrations. The as obtained JO intensity parameters Ω2 (5.31–5.21 pm2) and Ω4 (4.89–5.84 pm2) indicated the ligand behavior of the Eu–O bonds and a high asymmetrical and covalent environment around Eu3+ ions in the present host matrix. In comparison with other Eu3+-doped GCs, diopside based GCs containing high fraction of SrO exhibited adequate photoluminescence for optical lighting and display devices.Initiative d'excellence de l'Université de Bordeau

Dependence Dependence of Eu3+ photoluminescence properties on structural transformations in diopside-based glass-ceramics

Herein, diopside based glass-ceramics (GCs) were produced by sintering of glass powder compacts at 850 degrees C for 300 h. A special attention was paid on understanding the influence of structural transformations upon substituting strontium for calcium on the Eu3+ emission behavior. X-ray diffraction and Raman spectra showed the formation of diopside (CaMgSi2O6) in Sr-free glasses. Introduction of Sr led to the appearance of Sr-akermanite (Sr2MgSi2O2), whose formation increased continuously with increasing Sr/Ca ratio. The photoluminescence spectra exhibited intense D-5(0) -> (7)Ej transitions of Eu3+ ions. The intensity parameters (Omega(2) and Omega(4)) and the Eu-O ligand behavior were determined using the Judd-Ofelt (JO) theory from the emission spectra as a function of various Sr concentrations. The as obtained JO intensity parameters Omega(2) (5.31-5.21 pm(2)) and Omega(4) (4.89-5.84 pm(2)) indicated the ligand behavior of the Eu-O bonds and a high asymmetrical and covalent environment around Eu3+ ions in the present host matrix. In comparison with other Eu3+-doped GCs, diopside based GCs containing high fraction of SrO exhibited adequate photoluminescence for optical lighting and display devices. (C) 2017 Elsevier B.V. All rights reserved