Regulation of the Metal Center and Coordinating Anion of Mononuclear Ln(III) Complexes to Promote an Efficient Luminescence Response to Various Organic Solvents.

A series of mononuclear lanthanide complexes [Ln()(NO)], (Ln = Dy(III), ; Tb(III), ; and Eu(III), ; = (,)-,-bis((1-methyl-1-benzo[]imidazol-2-yl)methylene)cyclohexane-1,2-diamine) is obtained by reacting -methylbenzimidazole-2-carbaldehyde () and 1,2-cyclohexanediamine () with Ln(NO)·6HO under solvothermal conditions. ligand is produced via an in situ Schiff base reaction of two molecules of and one molecule of . The metal center Ln(III) is in a NO environment formed by and NO. NaSCN is added on the basis of synthesis. One SCN replaces one of the three coordinated NO anions in the structure, and the complex [Dy()(NO)(SCN)]·CHCN () is synthesized. The complex shows excellent luminescence response to petroleum ether (PET), an organic solvent. To the best of our knowledge, this study is the first to use a complex for sensing responses to PET. When the metal center is changed, the obtained mononuclear complexes and show an excellent luminescence response to tetrahydrofuran (THF). Lastly, obtained by changing the coordinating anion shows an excellent luminescence response to dichloromethane. Herein, for the first time, we regulate the metal center and coordinating anion of lanthanide complexes to adjust the recognition and response of these complexes to different organic solvents.