1. Extra credit Extra credit 1 – ionic radii trends Extra credit 2 – solving MIMT single crystal structures Work on these must be completed individually. Due date: May 14 th

2. Exploring biological functionality Enzymes –Complex systems that often contain metals at active site –Metals are particularly import for redox enzymes Bio-inorganic chemistry –Synthesis of model compounds

3. The biological nitrogen cycle

4. Nitrogenase Nitrogenase consists of 2 proteins: dinitrogenase reductase and dinitrogenase Overall reaction dinitrogenase reductase dinitrogenase 16 ATP required for each reduction of N 2 -> 2 NH 3

5. Some bacteria fix nitrogen only when involved in a symbiotic relationship with plants

6. Leghemoglobin protects nitrogenase by binding oxygen A true cross-species collaboration: Plant makes the globin protein and bacterium makes the heme cofactor

7. Industrial Haber process (N 2 -> NH 3 ) T = 400-500 °C p = 300-1000 atm

8. Dinitrogenase model compound

9. Oxygen binding in body

10. You will make model compound, Co(salen) Co(salen) can bind oxygen, just like the biological heme molecule

11. Oxygen binding depends on Co environment Co(salen) exists with Co in a 4, 5, or 6 coordinate site Solvated Co(salen) only binds O 2 when it is 5 or 6 coordinate In crystals: Solvated:

12. Experimental apparatus for measuring O 2 binding