Development of Fluorescent Probes for Environmental Sensing and Detection of Heavy Metals

1. Development of Fluorescent Probes for Environmental Sensing and Detection of Heavy Metals Xiu R. (James) Bu Department of Chemistry Clark Atlanta University • March 10, 2003

2. Initial state: localized Problem development Delocalization Penetration Soil Water Final state: soil and underground water contamination Human Background-Problems-Destination of toxic metals Government sites: production and storage sites of weapons; nuclear power plant (cobalt from coolant water). Industrial sites metal plating; battery production/recycling (Pb and Ni); tanneries, fertilizers, and metal cleaning, etc.

3. Toxic heavy metals:Long-term exposure effects Cobalt-asthma like allergy, damage to heart, thyroid, and liver. Also cause mutation to living cells Nickel-carcinogenic, heart and liver damage Copper-liver damage Lead--nerve damage, brain and liver damage Mercury-kidney damage Chromium-irritant to nose, skin, and stomach; liver and kidney damage. Cadmium-lung damage,lung cancer, and high blood pressure

4. EPA’s current drinking water standards Cobalt N/A Nickel 0.1 mg/L Copper 1.3 mg/L Lead 0.05 mg/L Mercury 0.002 mg/L Chromium 0.1 mg/L Cadmium 0.01 mg/L Sensing sensitivity must be available in these ranges.

5. Area One: Remediation Goal: to remove toxic heavy metals. How ? Choices: using chemicals to remove chemicals or using natural components to remove chemicals. Wood- natural fiber, practically cost least !!! Readily available in vast amount !!!

6. Chemistry for possible modification of wood surface to enhance chelating capability

7. For A For B Development of wood fiber based remediation technology • For example: liquid filters

8. Area Two: Detection Goal: To seek a fast and portable as well as continuous monitoring probes. Advantages of Fluorescence Probes:  Highly sensitive  Less Interference  Tunable for wide applications (wavelength/selectivity)

9. Fluorophores Fluorophores Chelating unit Florescent unit I h c Upon chelating action, the fluorescence signal disappears or diminishes. Before chelating S1 S1 non-radiative So So A working fluorescent probe analyte Sensing result

10. Technical approaches Fluorescent unit  Highly emission intensity-high sensitivity  Near IR emission reducing interference Ligand unit  Fast action for chelating  Enhanced selectivity for target analytes Design features N N N O O O O N N O Design features:  D-A based dyes  Supramolecular structure-based (dendritic, allosteric…) bi-dentate tetradentate Molecular probes Polymer based probes

11. Technical approaches (cont.) Polymer backbone ligand Chemical structure of a typical fluorophore Tetrahedron Lett. 42, 805(2001). Tetrahedron Lett. 37, 7331 (1996). Polym. Prep. 37(1), 599 (1996). Configuration of polymer based probes fluorophore Chemical structure of a typical polymer probe

12. Synthetic route to new polymer probe

13. Expected measurable achievements Publications-refereed journals Students training Technology transfer Academic collaboration Government collaboration

14. There will be always a time to go.