An aqueous ratiometric ESIPT sensor with a 87 nM (15.4 ppb) detection limit was successfully synthesized and applied for detection of all oxidation states of palladium species.

Two novel conjugated polymers containing a 2,2'-biimidazole moiety have been designed, synthesized, and demonstrated to be used as an effective fluorescent sensing platform for detection of Ag(+) and cysteine. This is the first example utilizing a fluorescent conjugated polymer-Ag(+) complex to selectively detect Cys with a nanomolar range detection limit.

A novel conjugated polymer chemosensor 1 containing 2,6-bis(2-thienyl)pyridine has been synthesized and exhibits a high sensitivity and selectivity for palladium ion detection based on the fluorescent quenching effect.

Polyhedral oligomeric silsesquioxane (POSS)-containing red fluorescent nanoparticles were designed and prepared for rapid detection of aqueous fluoride ions by virtue of the fluoride-triggered self-quenching of perylene bisimide dyes in nanoparticle cores.

Based on the aggregation-induced fluorescence quenching mechanism, a 2,6-dithienyl-4phenylpyridine-containing conjugated polymer (P-A) has been designed and synthesized via a Sonogashira coupling reaction as an efficient fluorescent sensor for palladium and platinum ions. The metal ion-sensitivity of P-A was evaluated using a series of transition metal ions in aqueous solution. On binding to Pd 2+ or Pt 4+ , fluorescence quenching of P-A was demonstrated by an approximately 80% reduction in the fluorescence intensity, while no obvious fluorescence change could be observed in the presence of other metal ions. Compared with its small molecular counterpart, P-A exhibits higher sensitivity and selectivity. The fluorescence intensity of P-A has shown a linear response to both Pd 2+ and Pt 4+ in the concentration range of 1-10 mM with a detection limit of 1 Â 10 À6 M in aqueous solution. It has been demonstrated that the sensitive property of the polymer sensors for the palladium and platinum ions is highly dependent on the fine structure of the conjugated polymers. The fluorescence quenching can be attributed to the Pd/Pt-induced aggregation of the polymer chains, which has been proved by fluorescence anisotropy methods. These results indicate that the fluorescence-amplifying method based on the aggregation-induced fluorescence quenching mechanism has enormous potential for the development of highly efficient fluorescence sensors towards the detection of palladium and platinum ions.

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