Photoluminescence and Coordination Behaviour of Lanthanide Complexes of Tris (Aminomethyl)Ethane-5-Oxine in Aqueous Solution

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• 作者：Rifat Akbar ; Minati Baral ; B K Kanungo
• 关键词：Lanthanide ; Fluorescence ; PET ; OFF − ON − OFF sensor ; Sparkle ; model
• 刊名：Journal of Fluorescence
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：27
• 期：1
• 页码：89-103
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Biomedicine, general; Biological and Medical Physics, Biophysics; Biotechnology; Biochemistry, general; Analytical Chemistry;
• 出版者：Springer US
• ISSN：1573-4994
• 卷排序：27

文摘

Photophysical properties of a multidentate tripodal ligand, 5,5′-(2-(((8-hydroxyquinolin-5-yl) methylamino)methyl)-2-methylpropane-1,3-diyl) bis (azanediyl)bis (methylene)diquinolin-8-ol, (TAME5OX), with La3+ and Er3+ ions have been examined for photonics applications. The change in behavior in electronic spectra of these complexes reveals the use of TAME5OX as a sensitive optical pH based sensor to detect Ln3+ ions whereas indication of strong green fluorescence allows simultaneous sensing within the visible region in competitive medium. The intense fluorescence intermittently gets quenched under acidic and basic conditions due to photoinduced intramolecular electron transfer from the excited 8-hydroxyquinoline (8-HQ) moiety to the metal ion. This renders these compounds the OFF-ON-OFF type of pH-dependent fluorescent sensor. The thermodynamic stability and coordination behaviour of the chelator with the said lanthanide ions have also been probed by potentiometric, UV − visible and fluorescence spectrophotometric method. TAME5OX forms protonated complex [Ln (H₄L)]4+ below pH ~4.0 which sequentially deprotonates through one proton process with increase of pH. The stability constants of neutral complexes have been determined to be in the range log β₁₁₀ = 32–34 and pLn in the range of 14–20, indicating TAME5OX is a good synthetic lanthanide chelator. Theoretical spectra were also calculated by ZINDO/s methodology at single excitations (CIS) level on PM7 as sparkle energy-minimized geometries.