Optoelectronic and biological quantification of semi-conducting, crimson europium chelates with fluorinated β-keto acid and N-donor ancillary ligands

Five luminescent ternary and one binary Europium(III) complexes were synthesised with beta-keto acid as primary ligand and neocuproine(neo), 5,6-dimethyl-1,10-phenanthroline(dmph), 4,7-diphenyl-1,10-phenanthroline (batho), 1,10-phenanthroline(phen), 2,2'-bipyridine (bipy) as ancillary ligands, via ecofriendly grinding method and were characterised through elemental analysis, UV-vis and IR spectroscopy, H-1-NMR and C-13-NMR spectroscopy. Their magnificent photophysical properties were studied by PL spectroscopy and numerically analysed by evaluating decay time of luminescence (tau), radiative (A(rad)), non-radiative transition rate (A(nrad)), luminescence efficiency (eta) and Judd-Ofelt intensity parameters (Omega(lambda)) for D-5(0) -> F-7(2,4) transitions. The branching ratio of D-5(0) -> F-7(2) transition in complexes (72-77%) makes it a potential laser emission transition. Optimum thermal stability, CIE colour coordinates value in deep red region and colour purity of nearly 90% (complex Eu6) make these complexes a promising candidate for red light emitting display devices. Energy transfer mechanism, optical band gap value and refractive indices were also explored for all complexes. The band gap energy of complexes lies within semiconductor range (2.87-3.83 eV), hence can have utility in lasers and military radars. Antioxidant and antimicrobial properties of all complexes were assessed. Complex Eu4 exhibited excellent antimicrobial activity, even better than standard drug, so the complex can be probed further as potent bactericidal agent.

Automated summary

Five luminescent ternary and one binary Europium(III) complexes were synthesized using an ecofriendly grinding method. The complexes were characterized and their photophysical properties were studied. Some of the complexes showed potential for laser emission transitions and red light emitting display devices.