Rapid Discovery and Structure-Property Relationships of Metal-Ion Fluorescent Sensors via Macroarray Synthesis.

A macroarray immobilisation of fluorophores on filter papers for sensing metal ions by in-situ reductive amination and carbodiimide coupling is reported herein. Chemometric approaches resulted in a rapid discovery of sensors that can synergistically discriminate up to 12 metal ions with great prediction accuracies. Covalently bound on paper, sensoring scaffolds that were synthesised from the macroarray format can readily be adopted as practical paper-based sensors with great reusability and sensitivity, achieving the limit of detection at low nanomolar level with some repeating spotting. Lastly, the discovered scaffolds were also confirmed to be functional as unbound molecules, thus paving the way for more diverse applications.

A novel indolium salt as a highly sensitive and selective fluorescent sensor for cyanide detection in water.

A highly sensitive fluorescent turn-on cyanide probe is developed based on benzylidenes containing methylindolium group. Three benzylidene derivatives were synthesized from the condensations of three benzaldehyde derivatives and methyleneindoline. Only one of these three derivatives shows strong blue fluorescent response selectively to CN- which can be clearly observed in submicromolar range as the result of the cyanide addition to the indolium group. The detection of cyanide with this compound is optimized in aqueous media using non-ionic surfactant and sonication method to give very low limit of detection in subnanomolar range. The probe is also developed into a paper-based and gel-based sensing kits that can readily detect cyanide ion in micromolar range by naked eye under a common black light (360nm) illumination.

Novel salicylaldehyde derivatives as fluorescence turn-on sensors for cyanide ion.

A novel series of fluorescent probes containing diphenylacetylene as fluorogenic units and salicylaldehyde as a CN(-) receptor were successfully synthesized by using sonogashira coupling. In the presence of Triton-X 100 non-ionic surfactant, the fluorophores exhibited fluorescence "turn-on" in response to CN(-) in aqueous media with the detection limit of 1.6 µM. The turn-on signal is the result of the conversion of the aldehyde to cyanohydrin via the internal acid catalyzed addition of cyanide. Using paper sensor strips, a naked eye detection of cyanide is possible down to 5 nmol.