Subcomponent self-assembly of a Fe(II) based mononuclear complex for potential NH3 sensing applications

Metal oxide and conducting polymer solid state sensors have occupied a substantial portion of NH3 gas sensor applications. Here, we present a new mononuclear Fe(II) complex with formula [FeL2](BF4)2 (L = (E)-2-((pyridin-2-ylmethylene)amino)-1H-benzo[de]isoquinoline-1,3(2H)-dione) (1) for potential NH3 sensing applications. Complex 1 was synthesized via subcomponent self-assembly. Clear color differentiation from pink to black can be observed by the naked eye at ambient conditions after adsorbing NH3 gas. 57Fe Mössbauer spectroscopy was employed to study the driving spin state change of the material 1@NH3, paving the way to the design of a new generation of sensors based on coordination complexes.