Design, Synthesis and Photophysical Characterization of Luminescent Metal Tetrazolate Complexes

Over the past few decades, the scenario of luminescent transition metal complexes has experienced a great blossom. In this context, the spotlight of the research program that I have carried out in my PhD studies has been dealing with the design, the preparation and the study of the photophysical properties of a new series of luminescent metal complexes containing anionic ligands such as 5-aryl tetrazolates [R-CN4]-. The choice of this specific class of nitrogen rich derivatives stemmed from the observation of how these ligands can effectively rule the luminescent output of the corresponding Ru (II) polypyridyls, Ir(III) bis-cyclometalates and tris carbonyl Re(I)-diimine complexes. In particular, the synthetic versatility of tetrazolate derivatives combined with the peculiar sensitivity to electrophilic additions – both permanent and reversible - that is displayed by the coordinated tetrazolate ring constitute the background for the further exploitment of their coordination chemistry and their applicative panorama. On these basis, we have recently prepared the first examples of anionic Ir(III) tetrazolate complexes and new Re(I)-based species containing ditopic tetrazolate ligands, with particular attention dedicated to their use as components for white light emitting Ir(III)-based ion pairs (“soft salts”), for covalently linked Ir(III)-Re(I) dyads, and for the investigation of Re(I) tetrazolate complexes as luminescent chemosensors. Moreover, studies which have dealt with Ru(II) tetrazolate complexes, pointed the way for the preparation of tetrazole –based Dye Sensitized Solar Cells.