Binuclear Ln (III) complexes: High‐efficiency sensing of acetonitrile/dichloromethane and magnetocaloric effect

At room temperature, 2‐aminomethylpyridine, Ln (NO 3 ) 3 ·6H 2 O and ( E )‐2‐((3‐methoxy‐2‐oxidobenzylidene)amino)ethanesulfonate ( L 1 ) in methanol and acetonitrile to obtain four complexes: [Ln 2 ( L ) 2 (NO 3 ) 4 ] (Ln = Sm ( 1 ), Eu ( 2 ), Gd ( 3 ), Tm ( 4 ), and L = ( E )‐2‐methoxy‐6‐(((pyridin‐2‐ylmethyl)imino)methyl)phenol). The original organic ligand L 1 and 2‐aminomethylpyridine reacted in situ under the catalyzed condition of Ln III ion to form a new Schiff base ligand L . In the above process, firstly, the C = N double bond in the original Schiff base ligand L 1 is broken and further combines with 2‐aminomethylpyridine to form a new Schiff base ligand L . As far as we know, this is rare in the formation of lanthanide complexes. When Complex 2 was subjected to luminescence test, it was found to have an extremely high selectivity to acetonitrile (CH 3 CN) and methylene chloride (CH 2 Cl 2 ). Therefore, after screening a variety of different organic solvents, here we explore a method that can quickly and efficiently respond to CH 3 CN/CH 2 Cl 2 . In addition, we can visually distinguish the response of Complex 2 to multiple volatile organic compounds (VOCs). The magnetocaloric effect (MCE) test of Complex 3 showed 18.7 J·kg −1 ·K −1 at 2 K for Δ H = 5 T.