Synthesis of fluorescein by ship in a bottle method in different zeolites

New J. Chem., 2017


The composites consisting of fluorescein (F) entrapped inside various zeolite structures (i.e. FAU, LTL, MFI, LTA) were prepared by the catalytic synthesis of the dye from the precursors (phthalic anhydride and resorcinol) adsorbed in zeolites. Zeolites (mostly H forms) played a role of the catalysts and of the matrices encapsulating the resulting dye molecules. It was revealed that the F loading and optical properties of composites depended on zeolite structure. The attained F loading corresponded to zeolite pore volume and aperture (HY>HL>HZSM-5  >> NaA). The fluorescence efficiency (i.e.intensity, stability and bleaching resistance) of composites was much higher than that of pristine F and depended on dye dispersion in the matrix (HL>HZSM-5> HY>>NaA). Various zeoliic matrices could be useful for controlled preparation of F composites suitable for different application (optical, microelectronic, medical). The attempts to encapsulate F during crystallization of zeolites (LTA, FAU, LTL) appeared not successful.

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