Sensores luminiscentes para el estudio de las anomalías en el orden de las moléculas de agua

Résumé

Water’s odd characteristics make the existence of life on earth possible. However, although water is the most studied liquid, the causes of the singularities of most of its properties are not known yet. Its peculiarities are mainly due to the unusual organization of water molecules, which are connected by hydrogen bonds. The variation of hydrogen bonds characteristics with temperature causes the alteration of the order of water molecules. Consequently, water’s properties show anomalous temperature dependencies. In this thesis the causes, effects, and influential factors of the density and dipolar anomalies of water have been investigated. These anomalies have been studied through their effect on the temperature dependence of the luminescence of Eu3+ ions, as these ions are excellent sensors of structure changes at the molecular scale. Moreover, as water is the solvent used for the development of nanomaterials applications in biomedicine, attention has been paid to the effect of water anomalies on them. In particular, the effect of the dipolar anomaly of water on the ion exchange process among fluoride luminescent nanoparticles has been investigated. The results obtained in this thesis have allowed to understand better how the order of water molecules is altered by temperature and pH and how these anomalies affect luminescent nanomaterials dispersed in water.