Microporous Lanthanide Metal-Organic Frameworks with Multiple 1D Channels: Tunable Colors, White-Light Emission, and Luminescent Sensing for Iron(II) and Iron(III).

A new series of isostructural lanthanide-based metal-organic frameworks, [H O][HN(CH ) ] [Ln L ] (Ln=Gd (1), Eu (2), and Tb (3); H L=1,3-benzenedicarboxylic acid), was prepared under solvothermal conditions. Single-crystal XRD studies reveal that these compounds are 3D microporous frameworks with 1D channels distributed in four different directions. The 1D channels contain protonated water molecules and trimethylammonium cations, which can be partially exchanged with different metal ions. Notably, these compounds do not contain any coordinated solvent molecules because the coordination sphere of the Ln ion is fully occupied by chelating and bridging carboxylate oxygen atoms. Tunable colors and white-light emission can be achieved by encapsulating different molar ratios of Eu and Tb ions in the Gd framework through cation exchange. In addition, the Eu framework can act as a sensitive and selective luminescence sensor for both Fe and Fe .