The optical and magnetic properties of redox-active d-block metal complexes with non-innocent ligands

Abstract

Redox-active metal organic complexes with ‘non-innocent’ ligands are promising candidates when it comes to developing novel homogenous catalysts. The related complexes have gained interest since they could be utilized as affordable base-metal containing compounds instead of expensive and scarce noble metal containing complexes. The complexes with non-innocent ligands undergo readily one- or multielectron oxidation/reduction processes, which are vital in catalytic processes. Therefore, the complexes have been studied for biomimetic model compounds for metalloenzymes.

These redox-active complexes have low-lying, intramolecular charge transfer processes that enable the compounds to absorb strongly electromagnetic radiation at low frequency range, namely, in the near-infrared range. In addition, the complexes possess interesting magnetic properties which are potentially influenced by photon excitation. Some of the redox-active complexes bear unpaired spins on the orbitals of the organic ligands. Redox-active complexes, in some cases, do exhibit bistability and are known to go through valence tautomerization process, where the sum of the electrons within the complex remains, while their locations and orientations vary. This may result in differing spin states within the complex and thus differing physical (optical and magnetic) properties between the tautomers.

These features are the key in order to use these complexes in various sensing applications or in molecular memory. Because of their intense absorptions, the redox-active complexes have also been considered as dye sensitizers in a titanium dioxide-based dye sensitized solar cells and other photovoltaic applications. The present thesis exhibits the synthesis, characterization and the redox-active, optical and magnetic properties of first-row d-block metal complexes with non-innocent ligands.