Lanthanide complexes based on a conjugated pyridine carboxylate ligand: structures, luminescence and magnetic properties

• Published in: RSC advances Vol. 1; no. 11; pp. 6192 - 6199
• Main Authors: Li, Rong-fang, Li, Rui-hao, Liu, Xin-fang, Chang, Xin-hong, Feng, Xun
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 10.02.2020; The Royal Society of Chemistry
• Subjects: Chemistry; Crystal structure; Crystallography; Dicarboxylic acids; dysprosium; Dysprosium compounds; Fluorescence; Hydrogen bonding; Hydrogen bonds; Infrared analysis; infrared spectroscopy; Ligands; Low temperature; Luminescence; Magnetic permeability; Magnetic properties; Photoluminescence; pyridines; Single crystals; temperature; Thermogravimetric analysis; thermogravimetry; X-ray diffraction
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c9ra10975g

Three lanthanide compounds have been synthesized, namely, {[Dy 2 (bpda) 3 (H 2 O) 3 ] 4 ·2H 2 O}(Dy-1), {[Sm(bpda) 2 ·(H 2 O)]·H 2 O} n (Sm-2) and {[Tb 2 (bpda) 3 (H 2 O) 3 ] 4 ·2H 2 O} (Tb-3) (H 2 bpda = 2,2′-bipyridine-6,6′-dicarboxylic acid). Their structures were determined by single crystal X-ray diffraction and characterized by elemental analysis, infrared spectroscopy and thermogravimetric analysis. Dy-1 and Tb-3 are isostructural with a conjugate bimolecular four-nuclear cluster structure constructed with intramolecular hydrogen bonds and they form a 3D supramolecular structure with intermolecular hydrogen bonding. Sm-2 is a one-dimensional chain structure and is further connected by intricate hydrogen bonds into a three-dimensional supramolecular structure. These three compounds exhibit significant characteristic luminescence from the ligand to the central Ln( iii ) ion, which is found by solid-state photoluminescence measurement. Sm-2 exhibits a long luminescence lifetime and high fluorescence quantum yield. A slow relaxation phenomenon is observed for the dysprosium compound by measuring the alternating-current susceptibility at low temperature and the underlying mechanism was further confirmed by theoretical calculations. The structures, fluorescence and magnetic properties of series three lanthanide complexes have been investigated. Dysprosium complex exhibit the single-molecule behavior.