Sensitivity of a solidEu(III) complex towards acetonitrile vapor: structural and spectroscopic characterization

Abstract The Eu(III) nitrate complex of the meso- N, N’-bis(2-pyridylmethylene)-1,2-(R,S)-cyclohexanediamine ligandhas been synthesized and characterized by single crystal and powder X-ray diffraction. Thecrystal lattice of the complex is capable to adsorb and desorb selectively acetonitrile molecules, at 293 K upon an acetonitrile vapor pressure of ∼0.1×105 Pa. This process, which is partially reversible, can be easily followed by both powder X-ray diffraction (P-XRD) and Eu(III) luminescence spectroscopy.The acetonitrile molecule, located in the outer coordination sphere of the metal ion, does not affect the radiative transition probability of 5D0 level of Eu(III) as well as it does not activate further non-radiative channelsfrom this level. On the other hand, this molecule is capable to affect the energy position and intensities of the crystal field components of the 5D0→7F2transition.The complex in solid form can be considered a promising material for the optical sensing of acetonitrile vapors.