A Turn-On Fluorescent Probe for Detection of Sub-ppm Levels of a Sulfur Mustard Simulant with High Selectivity.

A new type of fluorescent probe capable of detecting a sulfur mustard (SM) simultant at a concentration of 1.2 µM in solution and 0.5 ppm in the gas phase has been developed. Owing to its molecular structure with a thiocarbonyl component and two piperidyl moieties integrated into the xanthene molecular skeleton, this probe underwent a highly selective nucleophilic reaction with the SM simultant and generated a thiopyronin derivative emitting intensive pink fluorescence. The distinct difference in electronic structure between the probe and thiopyronin derivative generated a marked shift of the absorption band from 445 to 567 nm, which enabled an optimal wavelength propitious for exciting the thiopyronin derivative but adverse to the probe. Such efficient separation of the excitation wavelength and tremendous increase in fluorescence quantum yield, from less than 0.002 to 0.53, upon conversion from the probe to the thiopyronin derivative, jointly led to a distinct contrast in the beaconing fluorescence signal (up to 850-fold) and therefore the unprecedented sensitivity for detecting SM species.

A new colorimetric, near-infrared fluorescent probe for rapid detection of palladium with high sensitivity and selectivity.

A new type of colorimetric, fluorescent palladium (Pd) probe characterized with beaconing fluorescence signal in the quiet near-infrared (NIR) region (centered ~ 717 nm), recognition response time of approximately 3 min, limit of detection (LOD) down to 5.1 ppb, and excellent recognition specificity over a wide range of interfering metal cations was developed. It is believed that the probe underwent sequential Pd0-mediated oxidative addition and reduction elimination reactions, yielding typical D-π-A molecular skeleton of the final reaction product capable of intramolecular charge transfer (ICT). The benzothiazole moiety of the probe molecular skeleton is believed to play a vital trole in shifting the beaconing fluorescence signal to the quiet NIR region and accelerating the Pd0 recognition process of the probe via the formation of the fluorescent reaction product with largely extended π-delocalization. With unique advantages, the fluorescent probe we developed will find practical applications for detecting residual Pd with concentration below the safety margin in pharmacy and biomedical engineering.

A BODIPY-Based Fluorescent Probe for Detection of Subnanomolar Phosgene with Rapid Response and High Selectivity.

A new type of phosgene probe with a limit of detection down to 0.12 nM, response time of less than 1.5 s, and high selectivity over other similarly reactive toxic chemicals was developed using ethylenediamine as the recognition moiety and 8-substituted BODIPY unit as the fluorescence signaling component. The probe undergoes sequential phosgene-mediated nucleophilic substitution reaction and intramolecular cyclization reaction with high rate, yielding a product with the intramolecular charge transfer (ICT) process from amine to the BODIPY core significantly inhibited. Owing to the emission feature of 8-substituted BODIPY that is highly sensitive to the substituent's electronic nature, such inhibition on the ICT process strikingly generates strong fluorescence contrast by a factor of more than 23 300, and therefore creates the superhigh sensitivity of the probe for phosgene. Owing to the high reactivity of ethylenediamine of the probe in nucleophilic substitution reactions, the probe displays a very fast response rate to phosgene.