Syntheses, crystal structures and magnetic properties of a series of luminescent lanthanide complexes containing neutral tetradentate phenanthroline-amide ligands. Issue 6 (29th April 2019)

• Record Type: Journal Article
• Authors: Su, Qian-Qian; Fan, Kun; Jin, Xin-Xin; Huang, Xin-Da; Cheng, Shun-Cheung; Luo, Li-Juan; Li, Yao-Jie; Xiang, Jing; Ko, Chi-Chiu; Zheng, Li-Min; Lau, Tai-Chu
• Is Part Of: Inorganic chemistry frontiers. Volume 6:Issue 6(2019)
• Page Start: 1442
• Page End: 1452
• Publication Date: 2019-04-29
• Subjects: Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9qi00238c
• Languages: English
• ISSNs: 2052-1553

Abstract

Abstract : Six lanthanide compounds have been prepared from a neutral tetra-dentate ligand. Their luminescent and magnetic properties were investigated in detail. Abstract : A series of lanthanide (Ln ) compounds, [Eu III (L )2 (MeOH)(H2 O)](ClO4 )3 (1 ), [Tb III (L )2 (H2 O)](Cl3 ) (2 ) and [M III (L )2 (NO3 )](ClO4 )2 (M = Eu (3 ); Sm (4 ); Tb (5 ); Dy (6 )), have been prepared by the treatment of a neutral tetra-dentate ligand ( N 2, N 9 -dibutyl-1, 10-phenanthroline-2, 9-dicarboxamide, L ) with various Ln(iii ) salts in MeOH. All of the compounds have been structurally characterized by X-ray crystallography. It is noted that the anions of the Ln(iii ) salts play crucial roles in the solid-state structures and the properties of the resulting complexes. In compounds1 and2, the metal centres are 10- and 9-coordinated, respectively, which are surrounded by twoL ligands and solvent molecules. When the nitrate salts are used instead, four isostructural 10-coordinate Ln(iii ) compounds are obtained. The photophysical properties show that most of the compounds exhibit the characteristic emission peaks of Ln(iii ). LigandL acts as a very good 'antenna' to sensitize the Eu(iii ) emission, but not for other Ln(iii ) emissions. The quantum yield of3 is 75.4%, which is much higher than that of1 (17.6%) due to the –OH oscillators of the coordinated H2 O and MeOH molecules in1 . The magnetic properties of the Tb(iii ) compounds2 and5 and the Dy(iii ) compound6 were investigated in detail as a natural extension of our previous study of the effect of high-coordination number on the single-ion magnet (SIM) behaviour of 3d compounds. The results show that subtle changes in the coordination environment have significant effects on the magnetic behaviour. The 9-coordinate compound2 is not a single ion magnet (SIM), but both 10-coordinate compounds5 and6 exhibit field-induced SIM behaviour. It is also interesting to note that, upon the application of a small dc field, 5 exhibits two distinct relaxation processes, which is uncommon in Ln-based SIMs.