Search

Abstract: Zeolite losod prepared with tetrabutylammonium hydroxide was applied as matrix for sulfur anion-radicals thermally generated from precursors (elemental sulfur and alkalis or alkaline oligosulfides). We hoped that large los cages could favor formation and stabilization of big radicals (e.g. red ). The products with maintained LOS structure, however, always showed light green or blue coloration (due to and radicals) and bigger radicals never were detected (EPR). It is likely that the sulfur radicals in the products occupy rather eri cages in LOS structure, whereas the large los cages do not accommodate any radicals, because several of them could stay there and subsequently recombine to ordinary oligosulfides. Some reduction of los cage size by means of Cs or K cations resulted in a degradation of LOS structure. Introduction of sulfur compounds already during the losod crystallization disturbed formation of LOS structure. [Copyright &y& Elsevier]

Abstract: MOF-5 and ZIF-8 were used for the first time as matrices for pigments containing entrapped dmit. The chromophore was introduced either by impregnation or by its synthesis from CS2 inside the matrices. Pigments with ZIF-8 resisted washing and maintained the structure, while these with MOF-5 underwent structure altering or amorphization. [Copyright &y& Elsevier]

Fluorescein was entrapped inside FAU type zeolite (Y) by generating it from resorcinol and phthalic anhydride. Prior to the formation of fluorescein, zeolite Y was modified with various cations (H, Zn, Ce, Na, K). The modified zeolite acted as catalysts for the fluorescein Friedel–Crafts reaction synthesis, while at the same time it played a role of matrix for the stabilization and homogeneous dispersion of the guest molecules. The nature of the different cations influenced the content of fluorescein generated in the zeolite, and favoured the formation of some dye isomers (i.e. anion, dianion, cation or transition metal complex). The contribution of different fluorescein derivatives in the products was reflected in their absorption and fluorescence properties. The H-, Ce-, and Zn- containing Y zeolites revealed the highest content of fluorescein due to their distinct acid active sites. The composites with H- and ZnY zeolites indicated much higher fluorescence than that of the pristine fluorescein. Moreover, fluorescein in zeolite Y matrices did not show any photobleaching under continuous illumination (λ = 730 nm, in a two-photon experiment for 180 s), which suggests that these materials could be used for biomedical applications. [ABSTRACT FROM AUTHOR]