Investigation of a Tetrathiafulvalene-Based Fe2+ Thermal Spin Crossover Assembled on Gold Surface

A thick film and a monolayer of tetrathiafulvalene-based Fe2+ spin-crossover complexhave been deposited by solution on a Au (111) substrate, attempting both self-assembling monolayerprotocol and a simpler drop-casting procedure. The thermally induced spin transition has beeninvestigated using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS).Temperature-dependent investigations demonstrated the retention of the switching behavior betweenthe two spin states in thick molecular films obtained by drop-casting, while in the monolayer sample,the loss of the spin-crossover properties appears as a possible consequence of the strong interactionbetween the sulfur atoms of the ligand and the gold substrate.