Synthesis, Spectral Characterization and Potential Fluorescent Properties of Three Lanthanide(III) Ions Complexes with Nalidixic Acid

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2023-06, Vol.294, p.122561, Article 122561
• Main Authors: Kosińska-Pezda, Małgorzata, Maciołek, Urszula, Zapała, Lidia
• Format: Article
• Language: English
• Subjects: Lanthanide complexes; Lanthanide emission; Nalidixic acid; Spectral characterization
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2023.122561

[Display omitted] •The three lanthanide complexes of nalidixic acid have been prepared and characterized.•The photoluminescent behaviour of the complexes was investigated.•Nalidixate ligands effectively sensitize lanthanide ions.•5D4→7F5 transition is responsible for green emission of synthesized terbium complex.•4F9/2→6HJ transitions correspond to blue-yellow emission of Dy(III) complex. Three new solid lanthanide complexes with nalidixic acid (HNal) with the stoichiometry [Ln(Nal)3]·5·.5H2O (Ln = Tb, Dy and Ho) were synthesized applying the green synthesis method from the aqueous solutions without the organic solvent addition and fully characterized by the elemental analysis, XRF, complexometric titration, gravimetric analysis, molar conductivity and solubility measurements, powder X-Ray diffraction, UV–Vis and infrared (FT-IR) spectroscopies. Moreover, the luminescent properties of the Tb(III), Dy(III), and Ho(III) complexes in the solid state and in the solutions were investigated. On the basis of the detailed spectral analysis, it was concluded that the nalidixate ligands bind to the lanthanide ions by the bidentate carboxylate and carbonyl groups while water molecules belong to the outer coordination sphere. At the excitation of UV light, the complexes exhibited characteristic emission of central lanthanide ions, the intensity of which depends significantly on the excitation wavelength and/or the solvent. Thus, the application of nalidixic acid (apart from biological activity) for the synthesis of luminescent lanthanide complexes was confirmed which can find potential applications in the field of photonic devices and/or bioimaging agents.