Compuestos luminiscentes cicloplatinados con propiedades multifuncionales

Abstract

Square-planar platinum(II) complexes with conjugated aromatic ligands constitute a new class of supramolecular materials with interesting spectroscopic properties of great versatility due to their tendency to stack through metallophilic Pt(II)-Pt(II) interactions, modified and, sometimes assisted, by π···π interactions between the aromatic ligands. These properties are modulated by the type of ligands, the charge of the complex and/or the microenvironment, both in the ground state and in the excited state. In particular, platinum(II) cyclometalated compounds are of great interest due to their attractive photophysical properties with applications in several areas. In this context, this PhD Thesis focuses on the synthesis, characterisation and analysis of the properties of new luminescent systems based on cycloplatinated(II) complexes bearing isocyanide, isocyanide/alkynyl or acyclic carbenes ligands. Two series of chloride/isocyanide-type complexes [Pt(C^N)Cl(CNR)] (R = Xyl and tBu) and their corresponding alkynylation process to obtain acetylide/isocyanide-type compounds [Pt(C^N)(C≡CR')(CNR)] have been studied. The variation of the isocyanide, cyclometalated (C^N) or alkynyl ligands has allowed us to investigate the influence of these ligands on the structure, packing and on the photophysical properties. This study, supported by theoretical calculations, has shown that compounds with planar cyclometalated ligands based on the phenylpyridinyl group exhibit a greater tendency towards molecular aggregation through non-covalent intermolecular interactions Pt···Pt and/or π···π, which govern their photophysical properties, simultaneously generating mechanochromic behavior and aggregation-induced emission (AIE). These long-range molecular interactions are favoured in Cl/CNBut derivatives, resulting in multifunctional supramolecular materials with vapochromic, solvatochromic, mechanochromic and thermochromic properties. In addition, cis and trans-isomers [Pt(C^N)(C≡CR')(CNR)] were successfully isolated separately by using different synthetic pathways, which has allowed us to study the effect of cis/trans configuration on optical properties and their ability to act as selective cation sensors. Furthermore, a family of acyclic carbene-type luminescent complexes [Pt(C^N)Cl{C(NHXyl)(NHR)}] has been prepared by nucleophilic addition of primary amines onto the coordinated isocyanide in the precursors [Pt(C^N)Cl(CNXyl)]. These derivatives represent the first examples of cycloplatinated acyclic diaminocarbene complexes with antiproliferative properties, as evidenced by cytotoxicity and DNA interaction studies carried out in collaboration with CIBIR.