Reactive sensing of gold (III) by coumarin tethered fluorescent probe through alkyne activation

• Published in: Journal of the Indian Chemical Society 2022-10, Vol.99 (10), p.100670, Article 100670
• Main Authors: Thakare, Milind S., Pawar, Nilesh S., Adole, Vishnu A., Patil, Dipak B., Patil, Vikas
• Format: Article
• Language: English
• ISSN: 0019-4522
• DOI: 10.1016/j.jics.2022.100670

A novel strategy, involving anchoring and un-anchoring of coumarin based fluorophore, has been established for the selective detection of Au3+ species. Selective sensing of Gold (Au3+) was triggered due to alkynophilicity of gold ions to create lateral fluorescence of a latent fluorophore. The 4-methyl-2-oxo-2H-chromen-7-yl 2-(2-phenylethynyl) benzoate (CEB) probe was synthesized by reacting 7-hydroxy-4-methylcoumarin with iodo-benzoic acid. CEB probe has an absorption at 300 nm and 335 nm which decreases gradually and new absorption appeared at 406 nm due to Au3+ promoted ester hydrolysis selectively over other metal ions with great sensitivity, which accompanies a turn on fluorescence change produced by 7-hydroxy coumarin. The principle behind this sensing strategy is activation of triple bond induced uniquely by Au+3 ions leading to cascade and delivers active fluorophore. The sensing mechanism was proposed and supported by 1H NMR, MS and TD-DFT experiments. The density functional theory (DFT) and time dependent density functional theory (TD-DFT) theoretical results of the CEB-probe and Au3+ reaction is in good agreement with the experimental results. Additionally, probe could be well incorporated onto the test strips for effective detection of Au3+. π-activation feature of Au+3 utilised for the reactive fluorescence sensing. [Display omitted] •Coumarin based Fluorescent Probe was prepared from 7-hydroxy-4-methylcoumarin.•Coumarin based Fluorescent Probe was used for Reactive Gold (III) Sensing By Alkyne Activation.•Dramatically shift UV absorption upon gold sensing from 330 & 335 nm–406 nm.•Fluorescence created by reactive gold ion sensing at 460 nm among the competing metals ions.