Enhanced Optoelectronic and Biological Potential of Virescent-Glowing Terbium(III) Complexes with Pyrazole Acid

Abstract

A series of five virescent color emitting terbium(III) complexes is fabricated by a cost-effective and eco-friendly solution precipitation technique with the utilization of 1-(4-methoxyphenyl)-5-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid (L) as a primary ligand and highly conjugated nitrogen donor secondary ligands such as bathophenanthroline (batho), 5,6-dimethyl-1,10phenanthroline (dmph), 1,10-phenanthroline (phen) and 2,2-bipyridyl (bipy). The elemental compositions of complexes are examined through energy dispersive x-ray and elemental analyses, whilst the binding nature of ligand with terbium(III) ion is confirmed using proton nuclear magnetic resonance and infrared spectroscopy. The band gap energy (E g ) of complexes is found in the range of 3.85-3.34 eV as evaluated from diffuse reflectance spectral data. The significant thermal stability of these luminescent materials (157°C) demonstrates their key role as virescent component in white organic light emitting diodes. The intense emission and decay time of complexes are explored through photoluminescent study. The good color purity and Commission International De I'Eclairage color coordinates promise the enhanced performance of these materials in lighting appliances. The sensitization phenomenon highlights the role of ligands in increasing the luminescence intensity of complexes. The biological assessment indicates that the complexes are potent antimicrobial and antioxidant agents. The aforementioned features extend the field of applications of complexes in laser technology and optoelectronic devices.

Augmentation of photophysical features and Judd–Ofelt analysis of extensively green glowing terbium (III) complexes with nitrogen donor ancillary ligands

“…The 13 C-NMR spectrum of the L and S1 complex provided in Fig. S2 of the supplementary file shows that the peak observed at 177.08 ppm, assigned to ketonic carbon, disappeared in the complex indicating the linkage of ligand to the metal ion through ketonic group [27]. Further, the peak due to the carboxylic group, present at 165.36 in ligand, also disappeared in complexes due to paramagnetic behavior of terbium ion and juxtaposition of the -COO¯ group with terbium (III) ions [27,28].…”

“…S2 of the supplementary file shows that the peak observed at 177.08 ppm, assigned to ketonic carbon, disappeared in the complex indicating the linkage of ligand to the metal ion through ketonic group [27]. Further, the peak due to the carboxylic group, present at 165.36 in ligand, also disappeared in complexes due to paramagnetic behavior of terbium ion and juxtaposition of the -COO¯ group with terbium (III) ions [27,28]. It is important to note that the peak at 39.08-43.92 ppm in the ligand spectrum, assigned to N-CH 3 moiety, shows no perturbation in spectra of complexes, which shows that its position is away from the binding site.…”

“…In this aforementioned equation, β r refers to the branching ratio of a specific emission peak, A(ψj→ψj') is the integrated area of a specific emission peak and the denominator is the summation of integrated areas of all emission peaks in the spectra. The branching ratios with respect to dominant transition 5 D 4 → 7 F 5 are determined by emission data and documented in Table 4 (44.76-59.06%), which designate that the complexes having branching ratios near 50% and can act as a promising candidate in lasers in view of the fact that laser action is based on the highly integrated intensity of emission lines [27,41]. These radiant materials emitted the photons in the same direction with the same wavelength which augments the optical activity displayed by laser appliances.…”