Flexible Ligand Based Lanthanide Three-Dimensional Metal-Organhttp://ri.conicet.gov.ar/admin/image/check-amarillo.pngic Frameworks with Tunable Solid-State Photoluminescence and OH-Solvent-Sensing Properties

Abstract

Luminescent 3D metal-organic frameworks constructed by<br />trivalent lanthanides (Nd3+, Sm3+, Eu3+, Gd3+, Tb3+) and a flexible<br />ligand (2-methylsuccinate) (Ln-msucc) have been hydrothermally<br />obtained as polycrystalline solids. They were fully characterized by<br />X-ray powder diffraction, thermal analysis, vibrational spectroscopy<br />and scanning electron microscopy. The crystalline structure and<br />topological features were elucidated and compared with those of<br />related Ln-MOFs. The magnetic studies reveal that Nd-msucc and<br />Gd-msucc present antiferromagnetic and ferromagnetic behavior<br />respectively. Moreover, the solid state photoluminescence properties<br />(SSPL) of all the compounds were fully explored. Depending on the<br />lanthanide content, these materials exhibited luminescence<br />performances in near infrared and visible regions. Particularly, the<br />photophysical behavior of the Eu phase was exhaustively examined<br />and the radiative and non-radiative constants and intrinsic quantum<br />yields were calculated. The hypersensitive nature of Eu3+ 5D0→7F2<br />transition allowed an in-depth study of the optical response in<br />presence of various protic and aprotic solvents. As far as we know,<br />the chemical-sensing studies employing Eu-msucc constitutes the<br />first case reported for a lanthanide succinate-derived framework.<br />The obtained results being promising for the elaboration of specific<br />chemical sensors based on this material.