Extra credit Extra credit 1 ionic radii trends

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

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

The biological nitrogen cycle

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

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

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

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

Dinitrogenase model compound

Oxygen binding in body

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

Oxygen binding depends on Co environment • In crystals: • Solvated: • 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

Experimental apparatus for measuring O 2 binding