Spin crossover self-assembled monolayer of a Co(II) terpyridine derivative functionalized with carboxylic acid groups

The deposition of a monolayer by direct self-assembly from solution of an active spin-crossover (SCO) complex via chemisorption has been achieved starting from the perchlorate salt of Co(II) bis(4-(4-carboxyphenyl)-2,2:6,2-terpyridine). MALDI-TOF MS, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) confirm the presence of an intact monolayer of SCO molecules grafted through carboxylate groups to the Ag surface. Three different spectroscopic techniques (Raman, XPS and X-ray Absorption spectroscopy, XAS) evidence a thermal spin transition of such monolayer of molecules. To our knowledge, this is the first example of an active SCO assembly in direct contact with a surface obtained by wet chemistry.