The smectites represent a versatile class of clay minerals, offering possibilities of applications in several industrial and scientific fields. The hectorite belongs to this class, but it has the advantage of production through low-cost and relatively fast methods, presenting a flexible and tailorable structure which allows modifications on its composition to better match the desirable application. The current thesis discusses the synthesis and characterization of hectorite-based materials designed to act as host lattices for optically active species. In view of that, since the common hectorite structure has OH- ions in its composition, it is not the optimum material for luminescence applications because the hydroxyl ions may lead to luminescence quenching via multiphonon deexcitation. For this reason, the nanoclay materials discussed in the current thesis were synthesized based on the hectorite structure, but replacing its hydroxyl ions with halogens, generating the fluorohectorite (F-Hec), chlorohectorite (Cl-Hec), bromohectorite (Br-Hec) and iodohectorite (I-Hec) materials. Moreover, from the best of my knowledge, the current research is pioneering in the synthesis of the Cl-Hec, Br- Hec and I-Hec materials. 

The halogen-hectorites (X-Hec) materials have been obtained with similar crystal structure to the nanocrystalline fluorohectorite, presenting a d001 spacing of 14.30 Å and nanoscale crystallite sizes. All X-Hec behave as mesoporous materials, having specific surface areas ranging from 240 to 540 m2g-1, showing also good thermal stability (up to 750 °C). Thus, the X-Hec materials show strong potential to act as host lattices for optically active species, generating luminescent materials. All X-Hec materials (without doping) show a blue-green emission under UV radiation and short persistent luminescence (ca. 5 s), having their luminescence features attributed to a titanium impurity which acts as the luminescent center in these materials. Furthermore, the XHec materials were proven to be suitable host lattices for rare earth ions (RE3+) through the doping of Cl-Hec and F-Hec materials with Eu3+ and/Tb3+ (without the usage of “antennas” compounds), producing red- and green-emitting materials.