Near-Infrared Luminescent Lanthanide Complexes of Quinolinol Ligands: Structure/Properties Relationship

The synthesis and the characterisation of lanthanide complexes with quinolinolato ligands, a class of complexes proposed as near-infrared emitters for several optical applications, with a full investigation of the structure/property relationship, valuable for a reliable interpretation of their photo-physical properties, are described in this thesis. This work has been addressed to a detailed investigation of the proper synthetic procedures useful to prepare pure products suitable for structural, spectroscopic and photo-physical studies. Several types of lanthanide quinolinolates have been identified and characterised depending on reaction’ conditions and on the nature of the ligand. The spectroscopic properties are discussed with the view to provide suitable tools to identify and characterise univocally the structural features of this class of complexes. The excited-state dynamics and light emission properties of Er-complexes have been investigated applying a reliable quantitative description of the non-radiative decay processes induced by the dipolar coupling between quencher groups and the lanthanide ion. It has been also demonstrated that the ligand emission is significantly affected by the supramolecular interactions in the crystal packing. The study of the magnetic properties of erbium quinolinolates evidences small magnetic interactions, due to the supramolecular arrangement, relevant in the optical behaviour of optically active ErIII derivatives. The lanthanide quinolinolates have also been incorporated into sol-gel glasses as promising low-cost materials for optical applications, with the aim to investigate the processing potential of this class of emitting molecules.