1. 1 Iron(III) Complex of a Crown Ether- Porphyrin Conjugate and Reversible Binding of Superoxide to Its Iron(II) Form Katharina Dürr, Brendan P. Macpherson, Ralf Warratz, Frank Hampel, Felix Tuczek, Matthias Helmreich, Norbert Jux,*, and Ivana Ivanović-Burmazović,* J. Am. Chem. Soc. 2007, 129, 4217 - 4228 Speaker ：鍾柏源

2. 2 Hemoglobin 維基百科， http://en.wikipedia.org/wiki/Hemoglobin O2O2 O2O2 Hemoglobin

3. 3 Superoxide dismutase (SOD) The SOD-catalysed dismutation of Superoxide may be written with the following half-reactions : where M = Cu (n=1) ; Mn (n=2) ; Fe (n=2) ; Ni (n=2) Journal of Inorganic Biochemistry, 2002, 91, 349–355

4. 4 Structures and formal oxidation states of iron-dioxygen complexes Chem. Rev. 1994, 94, 659-698

5. 5 Fe(III)-peroxo-porphyrin complexes

6. 6 Electron-withdrawing group J. Am. Chem. Soc. 1996, 118, 2008-2012 The effect of electron-withdrawing groups on the stability No reaction

7. 7 An interaction between the potassium ion and the coordinated peroxo ligand Infrared spectra of the oxygen-oxygen stretching region for (A) [K][Fe(OEP)O 2 ] (B) [Me 4 N][Fe(OEP)O 2 ] => (A) is more stable than (B). J. Am. Chem. SOC. 1988, 110, 1382-1388

8. 8 Switching on the Nucleophilic Reactivity of a Ferric Porphyrin Peroxo Complex J. Am. Chem. SOC. 1987, 109, 1425-1434 J. Am. Chem. Soc. 1998, 120, 2652-2653

9. 9 Synthesis of Crown Ether-Porphyrin Reflux 24hr

10. 10 X-ray crystal structure of [Fe Ⅲ (Porph)Cl]

11. 11 Synthesis H 2 Porph [Fe Ⅲ (Porph)Cl] ： FeCl 2 [(Fe Ⅲ (Porph)) 2 O] ： 2 M NaOH K[Fe Ⅲ (Porph)(CN) 2 ] ： KCN [Fe Ⅲ (Porph)(DMSO) 2 ] + ： DMSO [Fe Ⅲ (Porph)OH] ： water or NaOH [Fe Ⅱ (Porph)] ： by chemical reduction K[Fe Ⅲ (Porph)(O 2 2- )] ： KO 2

12. 12 To study the influence of the potassium ion Inorg. Chem. 2002, 41, 2761-2768 KCN β-pyrrolic protons ： -3 and -5 ppm Bu 4 N + CN - β-pyrrolic protons ： -8 to -10 ppm Authors interpret this to mean that the bulky Bu 4 N + cation cannot be coordinated by the crown ether.

13. 13 UV/vis absorption spectra [Fe Ⅲ (Porph)(DMSO) 2 ] + [Fe Ⅲ (Porph)OH][(Fe Ⅲ (Porph)) 2 O] [Fe Ⅱ (Porph)(DMSO) 2 ] K[Fe Ⅲ (Porph)(O 2 2- )] 420 nm 429 nm 414 nm 430 nm 440 nm

14. 14 UV/vis spectra for the reaction of [Fe Ⅲ Porph(DMSO) 2 ] + and KO 2 KO 2 or dithionite Before (λ max = 420 nm) After (λ max = 430 nm) Reduction by dithionite [Fe Ⅲ Porph(DMSO) 2 ] + = 5 x 10 -6 M KO 2 = 5 x 10 -5 M At 25 ℃ in DMSO

15. 15 Time-resolved spectra for the reaction of K[Fe Ⅲ (Porph)(DMSO)(O 2 2- )] and 5 x 10 -5 M HOTf HOTf K[Fe Ⅲ (Porph)(O 2 2- )] = 1 x 10 -5 M [HOTf] = 5 x 10 -5 M After (λ max = 430 nm) Before (λ max = 440 nm) At 25 ℃ in DMSO

16. 16 UV/vis spectra for the reaction of K[Fe Ⅲ Porph(DMSO)(O 2 2- )] and 0.1 M HOTf K[Fe Ⅲ (Porph)(O 2 2- )] + 0.1 M HOTf

17. 17 Conclusion 1

18. 18 Time-resolved spectra of the reaction of [Fe Ⅲ (Porph)(DMSO) 2 ] + and KOH KOH

19. 19 Spectral changes during the reaction of [Fe Ⅲ (Porph)(DMSO)OH] and KO 2 KO 2

20. 20 Spectral changes upon mixing mCPBA with TBPH and [Fe Ⅲ (Porph)Cl] J. Am. Chem. SOC. 1984, 106, 755-764 m-chloroperbenzoic acid (mCPBA) 2,4,6-tri-(tert-butyl)phenol (TBPH) TBPH forms an oxygen-centered radical, which results inan increase of absorbance at 380, 400, and 630 nm. mCPBA = 10 -3 M TBPH = 10 -1 M [ Fe Ⅲ (Porph)Cl] = 1.3 x 10 -5 M Before After mixing At r.t in KCl-saturated DMSO/CH 3 CN

21. 21 Conclusion 2

22. 22 Cyclic voltammograms of [Fe Ⅲ (Porph)Cl] and [Zn Ⅱ (Porph)] b) Redox couples for [Zn Ⅱ (Porph)] under nitrogen a) Redox couples for [Fe Ⅲ (Porph)] + under nitrogen -1.54V -1.06V 0.225V -1.47V -0.983V 0.313V -1.23V -1.63V -1.56V -1.16V

23. 23 Mössbauer spectra of reduced 57 Fe-enriched [Fe Ⅲ (Porph)Cl] and K[Fe Ⅲ (Porph)(O 2 2- )] [Fe Ⅲ (Porph)Cl] [Fe Ⅲ (Porph)Cl] + KO 2 Mössbauer Parameters of the Studied Complexes in Frozen DMSO at 80 K

24. 24 Kinetics and Thermodynamics

25. 25 Time-resolved spectra for the reaction between [Fe Ⅱ (Porph)] and KO 2 [Fe Ⅱ (Porph)] = 5 x 10 -6 M [KO2] = 5 x 10 -4 M At 25 ℃ in DMSO KO 2

26. 26 Plots of k obs versus [O 2- ] for the second step of the reaction of 5 x 10 -6 M complex and KO 2 ■ :starting from the Fe(II) complex and using different mixing volume ratios ○ :starting from the Fe(II) complex and preparing a new solution for each [O 2 ] △ :starting from the Fe(III) complex and preparing a new solution for each [O 2- ] =>From the slope of the plot the second-order rate constant k on was determined to be 36500 500 M -1 s -1 k obs / [O 2 - ] = k on

27. 27 Time-resolved spectra for the reaction of K[Fe Ⅲ (Porph)(O 2 2- )] and 5 x 10 -5 M HOTf K[Fe Ⅲ (Porph)(O 2 2- )] = 1 x 10 -5 M [HOTf] = 5 x 10 -5 M After (λ max = 430 nm) Before (λ max = 440 nm) At 25 ℃ in DMSO First-order k obs = k off k off = 0.21 0.001 s -1 K O 2 - = k on / k off = (1.7 0.2) x 10 5 M -1

28. 28 Changes in absorbance upon addition of O 2- to a solution of [Fe Ⅱ (Porph)(DMSO) 2 ] [Fe Ⅱ (Porph)(DMSO) 2 ] = 5 x 10 -6 M With electrolyte K O 2 - = (0.9 0.1) x 10 5 M -1 Without electrolyte K O 2 - = (1.4 0.1) x 10 4 M -1

29. 29 Time-resolved spectra for the reaction between [Fe Ⅲ (Porph)Cl] and KO 2 [Fe Ⅲ (Porph)Cl] = 5X10 -6 M [KO2] = 2.5X10 -5 M Mixture of DMSO/CH 3 CN 25 ℃ - 40 ℃

30. 30 Eyring plot for the second reaction step [[Fe Ⅲ (Porph)Cl]] = 5 x 10 -6 M [KO2] = 1 mM In the DMSO/CH 3 CN mixture (30% DMSO) Eyring Equation k B = Boltzmann's constant [1.381·10 -23 J · K -1 ] T = absolute temperature in degrees Kelvin (K) h = Plank constant [6.626·10 -34 J · s] ΔH ‡ = 61.2 ± 0.9 kJ mol -1 ΔS ‡ = +48 ± 3 J K -1 mol -1

31. 31 Kinetic and Thermodynamic Parameters Kinetic and Thermodynamic Parameters for Binding of Superoxide to Fe Ⅱ (Porph) at 25 °C (Second Reaction Step)

32. 32 Dissociative mechanism => k obs = k on [O 2 - ] + k off k on = k 1 k 2 /k -1 k off = k -2 Second-order First-order

33. 33 Conclusions Authors have synthesized and characterized the new Fe(III)-porphyrin complex [Fe Ⅲ (Porph)Cl], which carries a covalently bound aza-crown ether in close proximity to the iron center. The second reaction step, binding of superoxide to the Fe(II) species and formation of the Fe(III)-peroxo complex, could be studied in detail. To our knowledge, this is the first time that superoxide concentration and temperature-dependent kinetic studies of reactions with superoxide. Moreover, authors have observed for the first time that the superoxide anion can bind reversibly to a metal center.

34. 34 Time-resolved spectra for the reaction of K[Fe Ⅲ (Porph)(O 2 2- )] and TBPH Fig. S2 K[Fe Ⅲ (Porph)(O 2 2- )] = 5X10 -6 M [TBPH] = 1X10 -2 M TBPH

35. 35 UV/vis spectra recorded every 90 s for the solution of [Fe Ⅱ (Porph)] mixed with O 2 - saturated DMSO Fig. S3 Fe Ⅱ (Porph)] = 2.5X10 -6 M

36. 36 Spectrum of an intermediate or side product ([Fe Ⅲ (Porph)OH]) in the reaction of [Fe Ⅲ (Porph)(DMSO) 2 ] + with KO 2 Fig. S4 [Fe Ⅲ (Porph)Cl] = 2.5X10 -6 M, [KO 2 ] = 1X10 -5 M [Fe Ⅱ (Porph)(DMSO) 2 ] = 2.5X10 -6 M

37. 37 The infrared spectrum Fig. S6 Fig. S7

38. 38 The IR spectrum of [Fe Ⅲ (TPP)] + in DMSO Fig. S8