Photoluminescent complexes of Eu(III), Tb(III) and Gd(III) with 3-thio- pheneacetate and 4,4′-dimethyl-2,2′-bipyridine: Synthesis, characterization and photophysical properties

Three crystals of lanthanide complexes with 3-thiophenoacetic acid (3-HTAA) and 4,4 '-dimethyl-2,2 '-bipyridine (dmbpy) ligands were synthesized. The structures of the complexes [Ln(2)(3-TAA)(6)(dmbpy)(2)] [Ln = Eu(III), Tb (III), Gd(III)] were determined by single crystal X-ray diffraction, where all crystals are isostructural and belong to the triclinic crystal system with P-1 space group. The complexes were characterized by CHN elemental analysis and spectroscopic techniques in the Infra-red region and Raman scattering. The dimeric structures have different modes of coordination using carboxylic and nitrogen groups present in the ligands. To investigate the photo-luminescence properties, the Eu(III) and Gd(III) complexes was selected. The triplet state (23,529 cm(-1)) was determined by the emission spectrum of the Gd(III) complex. Sparkle/PM3 model was also used to predict the ground state geometries of the Eu(III) complex. The intensity parameters (omega(2), omega(4) and omega(6)), energy transfer rates, radiative and non-radiative rates (A(rad) and A(nrad)), quantum efficiency (eta) and quantum yield (q) were determined by quantum mechanics calculation using the LUMPAC software. Crystal structures, spectroscopic properties and their photoluminescence behavior are discussed.

Automated summary

Three crystals of lanthanide complexes with 3-thiophenoacetic acid and 4,4'-dimethyl-2,2'-bipyridine were synthesized and their structures were determined. The complexes exhibited different coordination modes and their photoluminescence properties were investigated. The results provide insights into the crystal structures, spectroscopic properties, and photoluminescence behavior of the complexes.