Four New Stable Lanthanide Organic Frameworks: Highly Selective Luminescent Sensing and Magnetic Properties

Four new two‐dimensional isostructural lanthanide metal‐organic frameworks {[Ln(L)(LH)(H 2 O) 2 ]⋅H 2 O} n ( 1‐Ln ; Ln=Sm, Eu, Tb and Dy) were successfully assembled under hydro(solvo)thermal conditions by Ln 3+ salts and 4‐(3‐carboxyl‐1,2,4‐1H‐triazol‐1‐yl) benzoic acid (H 2 L). Compounds are isostructural and display a 2D 3‐connected fes 2‐periodic net with the point symbol of (4⋅8 2 ). Thus, 1‐Eu was chosen as a probe for sensing different metal ions and anions due to the excellent luminescence and good luminescent stability in water. 1‐Eu shows high selectivity for Fe 3+ , Cr 2 O 7 2− and CrO 4 2− ions, indicating that 1‐Eu should be an excellent candidate for luminescence sensing material. Furthermore, antiferromagnetic exchange couplings between the neighbouring Dy 3+ ions exist in 1‐Dy .