Two binuclear lanthanide complexes with 4-quinoline carboxylic acid: crystal structures and luminescent properties

Abstract

Two isomorphic lanthanide complexes [Eu₂(L)₆(H₂O)₄] · 2H₂O (1) and [Tb₂(L)₆(H₂O)₄] · 2H₂O (2), (HL = 4-quinoline carboxylic acid) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Both complexes are binuclear and each metal center adopts nine-coordination with nine oxygens from two H₂O molecules and carboxylates of three ligands; L exhibits three different coordination modes. Luminescent properties of 1 and 2 at room temperature indicate that the triplet-state level of this ligand matches better with the lowest excited state level of Eu(III) than with Tb(III).

Keywords:

• 4-Quinoline carboxylic acid
• Lanthanide complex
• Crystal structure
• Luminescent properties

Acknowledgements

This work was supported by the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality, Beijing Municipal Natural Science Foundation (No. 2082004) and the Major State Basic Research Development Program of China (973 Program, No. 2009CB930200).