New BODIPY chromophores bound to polyhedral oligomeric silsesquioxanes (POSS) with improved thermo- and photostability

Abstract

New hybrid dyes, analogs of the BODIPY laser dye PM567, with the chromophore group covalently bound to a POSS T8 group, have been prepared and their photophysical properties in ethyl acetate solution and in poly(methyl methacrylate) (PMMA) thin film solution have been studied. In PMMA solution and under comparative conditions, the dyes show higher thermostability than the parent dye PM567, the related compound POSS(iBu)8, and the corresponding unbound model dyes, because the first mass loss takes place at higher temperatures. In addition, their photostabilities in the same medium under irradiation with 365 nm light are much higher than those of the dye PM567 or an equimolar mixture of PM567 plus POSS(iBu)8 under the same conditions, indicating that the POSS moiety photostabilizes the bound BODIPY group. The different photostabilities could be a consequence of different reactivities of the hybrid dyes with self-generated singlet oxygen, because they show lower reaction rate constant values than PM567, although the observed tendency of these values does not correlate with that of the photodegradation quantum yield values. The new hybrid materials can be employed in applications where highly photostable and highly emissive dyes are required.