Spin‐Crossover Grafted Monolayer of a Co(II) Terpyridine Derivative Functionalized with Carboxylic Acid Groups
Víctor García‐López, Niccolò Giaconi, Lorenzo Poggini, Joaquín Calbo, Amélie Juhin, Brunetto Cortigiani, Javier Herrero‐Martín, Enrique Ortı́, Matteo Mannini, Miguel Clemente‐León, Eugenio Coronado
Abstract
Abstract The synthesis and characterization of a new Co(II) spin‐crossover (SCO) complex based on 4′‐(4‐carboxyphenyl)−2,2′:6′,2″‐terpyridine ligand are reported. This complex can be successfully grafted on silver surface maintaining the SCO behavior. Thus, atomic force microscopy (AFM), matrix assisted laser desorption ionization – time‐of‐flight mass spectrometry (MALDI‐TOF MS), Raman spectroscopy, and XPS measurements, upon surface deposition, evidence the formation of a monolayer of intact molecules grafted through carboxylate groups to the Ag surface. Three different techniques: Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and X‐ray absorption spectroscopy (XAS), supported by first‐principles calculations, confirm that the deposited molecules undergo a gradual spin transition with temperature. This phenomenon is unprecedented for a monolayer of molecules directly grafted onto a metallic surface from solution.