Tailoring Photoluminescence Properties in Ionic Nanoparticle Networks

• Published in: Chemistry : a European journal Vol. 20; no. 34; pp. 10763 - 10774
• Main Authors: Kronstein, Martin, Akbarzadeh, Johanna, Drechsel, Christina, Peterlik, Herwig, Neouze, Marie-Alexandra
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 18.08.2014; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Emission; Luminescence; Maxima; Nanoparticles; Nanostructure; Networks; Photoluminescence; Physical Sciences; SAXS; Science & Technology; silica; Stacking; Trends; BENZOBIS(IMIDAZOLIUM) SALTS; photoluminescence; SMALL-ANGLE SCATTERING; silica; BEHAVIOR; WAVELENGTH-DEPENDENT FLUORESCENCE; BRIDGED SILSESQUIOXANES; networks; SAXS; nanoparticles; HYBRID MATERIALS; OXIDE NANOPARTICLES; PI-STACKING; LIQUIDS
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201400392

To investigate the original and promising luminescence properties of ionic nanoparticle networks (INN), various material compositions were investigated. In this work, the linker used to network the silica nanoparticles was varied; numerous substituted or non‐substituted imidazolium, pyrazolium and pyridinium linkers are presented. Photoluminescence experiments on the INN hybrid materials revealed strong emission bands over a broad range in the visible region of the light spectrum. Varying the aromatic linker between the imidazolium units induced clear shifts of the emission maxima up to 100 nm, as a consequence of π–π stacking interactions. Steric hindrance and inductive effects of the substituents, introduced on the aromatic units, also strongly influenced the luminescence properties of the materials by modifying the π–π stacking between the imidazolium rings. Small and wide‐angle X‐ray scattering (SAXS, WAXS) experiments revealed a clear trend between the obtained structural parameters (short‐range order parameter and distance of the aromatic units within the hybrid material) and the luminescence quantum yields of the INN materials. Inducing luminescence: Interesting luminescence properties were observed in ionic nanoparticle networks containing no luminophore. “Playing” with the nanoparticle linker allowed tailoring of the excitation and emission wavelength over a broad range. A clear trend between the obtained structural parameters (obtained from small‐angle X‐ray scattering experiments) and the luminescence quantum yields of the ionic nanoparticle network materials could be evidenced (see figure).