| Abstract
| - Three water-soluble fluorescent probes have been specifically designed to determine free cyanideconcentrations up to physiologically lethal levels, >20 μM. The probes have been designed in such a wayas to afford many notable sensing features, which render them unique with regard to signal transduction,photophysical characteristics, and their application to physiological cyanide determination and safeguard.The probes are readily able to reversibly bind free aqueous cyanide with dissociation constants around 4μM3. Subsequent cyanide binding modulates the intramolecular charge transfer within the probes, a changein the electronic properties within the probes, resulting in enhanced fluorescence optical signals as a functionof increased solution cyanide concentration. The ground-state chelation with cyanide produces wavelengthshifts, which also enable the probes to sense cyanide in both an excitation and emission ratiometric manner,in addition to enhanced fluorescence signaling. This has enabled a generic cyanide sensing platform to berealized that is not dependent on fluorescent probe concentration, probe photodegradation, or fluctuationsin the intensity of any employed excitation sources, ideal for remote cyanide sensing applications. Further,the >600 nm fluorescence emission of the probes potentially allows for enhanced fluorescence ratiometriccyanide sensing in the optical window of tissues and blood, facilitating their use for the transdermal monitoringof cyanide for mammalian safeguard or postmortem in fire victims, both areas of active research.
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