Sistemas de Pt(II) y Pt(IV) basados en cromóforos 2-arilbenzotiazol: propiedades ópticas y aplicaciones biológicas stars

Abstract

This Thesis focuses on the synthesis and the study of the optical properties of organometallic luminescent platinum derivatives which incorporate substituted 2-arylbenzothiazole chromophores. It Is divided in a general Introduction, four separate Chapters and an Experimental section. The Pt(II) derivatives incorporate 2-4-(R-phenyl)benzothiazole ligands either with R = alkyne, to obtain trans(bisalkynyl) complexes or R = Br and Me2N substituents, used to synthesize cyclometalated derivatives. Labile groups (Cl, DMSO), cyanide, C6F5 and bioactive phosphines (having carboxilic o polyether units) have been used as auxiliary ligands to improve emission efficiencies or their solubility in biological media. Diferent oxidation reactions have been carried out which have allowed to pobtain luminescent bis(cyclometalated) Pt(IV) derivatives and to observe unusual reactivity patterns as the reduction of DMSO to SMe2 on the Pt center. The complexes with the basic Me2N-pbt ligand can also act as pH sensors, changing its spectroscopic properties. All the derivatives have been characterized by NMR and other spectroscopic techniques and, when possible, their structures have been confirmed by X-ray crystal diffraction. Most of the derivatives show intense modulable absorption and emission (fluorescence and/or phosphorescence) properties, which have been studied in different media (solution, solid or doped films at 298 K and 77K), obtaining the quantum yields and lifetimes of the emissions. In addition, the electronic transitions (absortion and emission), for selected complexes, have been also studied by DFT and TD-DFT theoretical calculations to support the assignments. Finally, the potential as anticancer drugs and as biomarkers of selected complexes have been studied in collaboration with the CIBIR. In particular their cytotoxicity towards cancer and non-tumoral cell lines and citolocatization inside the cells by confocal microscopy has been examined. Some of the derivatives are very sensible to the presence of molecular oxygen, and, in DMSO solutions, photooxidation of the solvent is observed enhancing the phosphorescence. Due to this, the potential of one compound as sensitizer in photodynamic therapy towards cancer cells has been studied, showing promising results.