The highly stable colloidal structure of graphene oxide (GO) in aqueous dispersion behaves as a platform for the molecular aggregation of dyes via a simple adsorption process. The interaction between dye and GO sheets is a critical factor for dye aggregation. Positively charged dyes interact with the negatively charged GO sheets in an aqueous dispersion via both electrostatic and p-p stacking interactions. The cationic nature of Pyronin Y (PyY) ensures that the dye molecules are quickly adsorbed on the GO sheets in the aqueous dispersion. GO-PyY composites with different ratios, which are stable for months, are prepared by simply mixing diluted aqueous dispersions of both components. Transition dipole-dipole interactions between the adsorbed dye molecules on the surface of the GO sheet causes the formation of H-aggregates of the dye at dilute concentrations. H-aggregates of PyY are characterized by spectroscopic techniques (UV-Vis, steady-state and time-resolved fluorescence spectroscopy). The morphology and thickness of the GO sheets and the dye adsorbed GO sheets were determined using atomic force microscopy (AFM) in tapping mode. AFM studies revealed that a great deal of PyY molecules interact on the edges of the GO sheets.3 Electronic supplementary information (ESI) available: Synthesis of graphene oxide (GO), SEM image of natural graphite flakes, EDX spectra of natural graphite flakes and GO, Raman spectra of natural graphite flakes and GO, TGA spectra of natural graphite flakes and GO, cross-sectional analysis of AFM images of GO and PyY adsorbed GO on a mica surface, and absorption spectra of PyY in deionized water and the GO aqueous dispersion. See
The interaction of rhodamine 101 (Rh101) with graphene oxide (GO) in aqueous dispersion was examined using advanced spectroscopic techniques. Rh101-GO composites in water were easily prepared by mixing an aqueous solution of both components since GO sheets interacted with the cationic dyes via π-π and electrostatic cooperative interactions. In the composites, the fluorescence of Rh101, which was a well-known laser dye with a high fluorescence quantum yield, could be efficiently quenched by GO. The quenching mechanism of Rh101 by GO sheets was evaluated by the Stern-Volmer (SV) equation and the time-resolved fluorescence studies. The results revealed that the fluorescence quenching of Rh101 by GO in the aqueous dispersion is due to the static quenching mechanism. The formation of the Rh101-GO composites at various pH values was spectroscopically monitored, and the spectroscopic results revealed that the composites were formed at the pH values studied except in the strong acidic media (pH ≈ 2). The interaction of Rh101 with GO in aqueous solution was spectroscopically followed in the presence of SDS (sodium dodecyl sulphate) at the surfactant concentrations above and below the CMC (critical micelle concentration). The fluorescence studies revealed that the fluorescence of Rh101 in the aqueous solution remarkably increased at the surfactant concentration forming the micelle of SDS.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.