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

• Published in: Research on chemical intermediates Vol. 48; no. 4; pp. 1685 - 1716
• Main Authors: Khatri, Savita, Hooda, Pooja, Ahlawat, Pratibha, Khatkar, S. P., Taxak, V. B., Kumar, Rajesh
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.04.2022; Springer Nature B.V
• Subjects: Antiinfectives and antibacterials; Antimicrobial agents; Antioxidants; Catalysis; Chemical analysis; Chemistry; Chemistry and Materials Science; Color; Display devices; Energy gap; Energy transfer; Europium; Infrared analysis; Infrared spectroscopy; Inorganic Chemistry; Ligands; Luminescence; NMR spectroscopy; Optoelectronics; Physical Chemistry; Refractivity; Spectroscopic analysis; Spectrum analysis; Thermal stability; Judd–Ofelt; Optical energy band gap; Europium complexes; Luminescence efficiency
• ISSN: 0922-6168; 1568-5675
• DOI: 10.1007/s11164-022-04658-0

Five luminescent ternary and one binary Europium(III) complexes were synthesised with β-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 eco-friendly grinding method and were characterised through elemental analysis, UV–vis and IR spectroscopy, 1 H-NMR and 13 C-NMR spectroscopy. Their magnificent photophysical properties were studied by PL spectroscopy and numerically analysed by evaluating decay time of luminescence (τ), radiative ( A rad ), non-radiative transition rate ( A nrad ), luminescence efficiency (Ƞ) and Judd–Ofelt intensity parameters (Ω λ ) for 5 D 0  →  7 F 2,4 transitions. The branching ratio of 5 D 0  →  7 F 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.