Preparation, Characterization, and Photophysical Study of Thiazine Dyes within the Nanotubes and Nanocavities of Silicate Host: Influence of Titanium Dioxide Nanoparticle on the Protonation and Aggregation of Dyes

The photophysical properties of thionine and methylene blue have been investigated in the absence and presence of titanium dioxide nanoparticles encapsulated into the different nanoporous silicate materials: zeolite-Y, ZSM-5, and MCM-41. The titanium dioxide loaded zeolite samples were prepared by the ion-exchange method and the formation of TiO2 nanoparticles into the zeolite host materials was ascertained by UV−visible diffuse reflectance spectroscopy and ICP-OES measurement. The crystallinity of the silicate host was found to be intact as characterized by powder X-ray diffraction, nitrogen adsorption and desorption isotherm studies and TEM. The encapsulation of TiO2 into the zeolite host leads to the protonation of the dyes, indicating that the acidity of channels increased significantly in the presence of titanium dioxide in the zeolite host. In the case of zeolite-Y, with increasing loading of titanium dioxide nanoparticles, the aggregation of dyes is found to decrease. The absorption and emission sp...