Tryptophan moiety based tetranuclear Ni(II) complex: synthesis, crystal structure and fluorescence sensing

• Published in: Inorganica Chimica Acta 2024-05, Vol.565, p.121962, Article 121962
• Main Authors: Mahish, Manas Kumar, Zangrando, Ennio, Vojtíšek, Pavel, Manna, Subal Chandra
• Format: Article
• Language: English
• Subjects: Crystal structure; Enantiomeric Schiff base ligand; Fluorescence sensing; Tetranuclear Ni(II) complex
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2024.121962

A tryptophan moiety based ligand was used to prepare a tetra nuclear Ni(II) complex, which was structurally characterized. The complex displays a selective response toward nitroaromatic compounds, especially for picric acid (PA). The sensing mechanism was investigated by spectral titration, time resolved fluorescence decay and DFT calculations, suggesting a combined effect of energy and electron transfer as well as electrostatic interaction for quenching pathway. [Display omitted] •Tryptophan moiety based a tetranuclear Ni(II) complex.•Selective fluorescence sensing for picric acid (PA).•Fluorescence sensing mechanism was investigated by fluorescence lifetime measurement and DFT calculations.•Selective fluorescence sensing may be due to a combined effect of energy and electron transfer as well as electrostatic interaction. Tryptophan moiety based Schiff base [H2L = N-(2-(hydroxy)-3-ethoxybenzylidene)tryptophan] was used to synthesize a tetra nuclear Ni(II) complex, namely [Ni4(L)4(dmf)(H2O)3].4(dmf).4(H2O) [dmf = dimethylformamide], which has been characterized by X-ray single crystal diffraction, electronic spectra and IR spectral techniques. The luminescent properties of the complex, examined in various organic solvents, highlighted that the metal complex displays a selective response toward nitroaromatic compounds, especially towards picric acid (PA), for which a LOD value of 3.93×10−7 M was calculated. The fluorescence sensing mechanism was investigated by fluorescence lifetime measurement and DFT calculations. The results showed that selective fluorescence sensing may be due to a combined effect of energy and electron transfer as well as electrostatic interaction.