“…In this case, the interlayer cations (such as sodium) balance the negative charges of the sheet (see Scheme ). Smectites, which belong to this group, are known for their ion-exchange properties with applications in many fields such as water depollution, catalysis, or drug delivery systems − The interlayer compensation cations can be replaced by a wide range of cations, either mineral or organic, such as organic cationic dyes. ,− In this case, the interactions of the clay mineral surface with the molecules of the dyes can modify their photochemistry and optical properties. ,− Recently, we have shown that phyllosilicates can be used to control the photophysics of the triarylmethane dye crystal violet . The interaction of the cationic dye, attracted by the negative octahedral charge of a commercially available synthetic 2:1 phyllosilicate (Laponite), with the platelet surface turns the nonemissive dye into a fluorescent compound .…”