Resumen de Spin crossover cobalt(ii) molecular nanomagnets as dynamic molecular systems
Paramagnetic mononuclear 3d-metal complexes with tailor-made "non-innocent" ligands have recently emerged as archetypical examples of dynamic molecular systems (DMSs). The enormous impact of DMSs on several domains of molecular nanoscience and nanotechnology stands from their ability to perform specific and selective functions under the control of an external stimulus that appropriately tunes their structural and electronic (optical, redox, and magnetic) properties. In this PhD Thesis, we describe, along with seven chapters, the chemistry and physics of a unique class of molecular nanomagnets based on mononuclear octahedral spin crossover cobalt(II) complexes with potential chemo-, electro-, or photoactive pyridinediimine (PDI) and terpyridine (TERPY)-type ligands. Because of their unusual combination of chemical (Brønsted or Lewis acidity, and redox) and physical (optical or luminescent, and magnetic) properties resulting from the metal and the ligand counterpart, they can be used in designing multifunctional and multiresponsive advanced magnetic materials for molecular spintronics and quantum computing technologies. One of the major achievements in this PhD Thesis was being able to modulate their spin crossover (SCO) and single-molecule magnet (SMM) properties by the ligand design through a variety of internal factors, either electronic (metal oxidation and spin states) or steric ones (ligand substituents and conformation), and eventually to switch them under the presence of an external stimulus, either chemical (pH and chemical analytes) or physical ones (light, electric and magnetic fields). Hence, mononuclear octahedral cobalt(II)-PDI and TERPY complexes behaving as spin crossover molecular nanomagnets afford an excellent chemical set of DMS models for fundamental studies on magnetic field-induced and chemo-, redox-, or photo-triggered, slow magnetic relaxation phenomena. In particular, they seem to be promising candidates for molecular spintronics and quantum computing devices like spin switches and capacitors or spin transistors and qubits. Besides, as briefly outlined in the last chapter, the spin crossover molecular nanomagnets presented in this PhD Thesis are particularly well-suited for their processing and addressing on different supports and measuring their single-molecule electron transport and quantum coherence properties, which are two major topics in molecular spintronics and quantum computing.
