Material hibrido organiko-ez-organiko fluoreszenteak aplikazio optikoetarako

Abstract

In the search of new hybrid materials suitable for optical applications, different dyes were occluded into the MgAPO-11 inorganic aluminophosphate. This zeolitic material has an AEL structure type containing very narrow one-dimensional nanochannels with a diameter of 6.5 x 4 Ų. Thus, taking into account the molecular dimensions of the dyes to be encapsulated herein, they will get tightly occluded into the inorganic host structure. For this reason, dyes must be added to the initial synthesis gel in order to success in the incorporation of those chromophores into the material. With this synthetic approach, chromophores are encapsulated in a highly ordered arrangement into the nanochannels of the big particles of the AEL structure, exceeding 10 μm in length, forcing the dye molecules to place with their long molecular axis parallel with respect to the channels' direction. Furthermore, the narrow size of the channels avoids dye aggregation into the aluminophosphate. Firstly, acridine (AC) and pyronin Y (PY) dyes were simultaneously encapsulated into the inorganic zeolitic host obtaining a highly fluorescent hybrid material. Moreover, as the transition dipolar moments of the two dyes are perpendicular to each other, and since an efficient FRET energy transfer takes place between them, a fluorescence emission colour-switching of the particles is seen under UV excitation light (from cyan to green) depending on the direction of the polarizers placed before detection. Finally, a different dye was occluded into the MgAPO-11, the LDS 722 dye, and as a result a highly fluorescent hybrid material emitting in the red edge of the electromagnetic spectrum was achieved. Its fluorescence quantum yield is around 50 times higher than that recorded for the dye in aqueous solution and, given that the LDS 722 shows intrinsic Non-Linear Optical properties, together with the fact that the chromophore molecules show a ordered arrangement into the system, an appropriate hybrid material for Second harmonic Generation (SHG) has been obtained.