Synthesis and property of probe and sensor molecuales

8-hydroxy-2-methylquinoline (Oxn) is a well-known building block for chelation enhanced fluorescent (CHEF) sensors for transition metals. It always shows a very weak fluorescence in organic solvent due to the efficient radiationless relaxation to the ground state by intra- and inter-molecular excited-state proton transfer (ESPT). In Oxn derivatives, when the excited-state proton transfer process is inhibited by protecting the hydroxyl group or coordination with metal ions such as Zn²⁺, Cd²⁺, etc, enhancement of fluorescence can be observed. Therefore, Oxn derivatives may be a potential candidate as a fluorescent chemosensor if the proton transfer process can be tuned by suitable chemical reaction or binding suitable metal ions. We synthesized 5, 7-dibromo-8-tert-butyldimethylsilyloxy-2-methyl-quinoline as a structurally simple colorimetric and ratiometric fluorescent chemosensor for F^-, which is based on combination of desilylation reaction and excited-state proton transfer. The sensor exhibits rapid response, excellent selectivity and sensitivity to F^-. Upon interaction with F^-, the sensor shows obvious changes of color from colorless to yellowish-green, meanwhile the blue fluorescence turns yellowish-green with enhanced intensity, which makes it possible to detect the F^- not only from the spectroscopic changes but also from the color changes. And the facile synthesis of the sensor with low-cost reagents makes the sensor readily accessible.

      Chemical Communications, 2011, 47, 3957–3959.

Analytical Methods, 2011, DOI: 10.1039/C1AY05194F.

We are applying the following strategies to design and synthesis the probes and sensors: (1) building novel structure for binding specific molecules, especially some extremely toxic metal cations and biomolecules; (2) modifying and adjusting certain selective binding sites to improve the selectivity of the sensors; (3) introducing small molecule sensor into conjugated polymer backbone to amplify the sensitivity of the sensors. By applying functional ligand, such as 2,6-bis(2-thienyl)pyridine, we expect to obtain a novel conjugated polymer sensor with extremely high sensitivity and selectivity for palladium group metal cations.

Chemical Communications, 2011, 47, 1731–1733.

Polymer Chemistry, 2011, DOI: 10.1039/C1PY00149C