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

• Published in: Applied organometallic chemistry 2021-03, Vol.35 (3), p.n/a
• Main Authors: Li, Juan, Tang, Ji‐Xia, Zou, Hua‐Hong, Mo, Kai‐Qiang, Wen, Chang‐Chun, Liang, Fu‐Pei
• Format: Article
• Language: English
• Subjects: Acetonitrile; binuclear ln (III) complexes; Chemistry; Dichloromethane; fluorescence; Gadolinium; Imines; Ligands; magnetocaloric effect (MCE); Room temperature; Selectivity; solvothermal reaction; VOCs; Volatile organic compounds; volatile organic compounds (VOCs)
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.6130

At room temperature, 2‐aminomethylpyridine, Ln (NO3)3·6H2O and (E)‐2‐((3‐methoxy‐2‐oxidobenzylidene)amino)ethanesulfonate (L1) in methanol and acetonitrile to obtain four complexes: [Ln2(L)2(NO3)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 L1 and 2‐aminomethylpyridine reacted in situ under the catalyzed condition of LnIII 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 L1 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 (CH3CN) and methylene chloride (CH2Cl2). Therefore, after screening a variety of different organic solvents, here we explore a method that can quickly and efficiently respond to CH3CN/CH2Cl2. 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 ΔH = 5 T. The example of quick, easy, and selective identification of CH3CN/CH2Cl2 is realized by using Complex 2 as fluorescence probe. Magnetic studies indicated that 3 displays large changes in entropy with changing magnetic field.