Synthesis,Structures And Properties Of [FeFe]-hydrogenase Models,Porphyrin-Fullerene Dyads And Porphyrin-Fullerene-[FeFe]-hydrogenase Model Triads

Porphyrin-fullerene dyads have received considerable attention, since they could be used as models for the photoinduced electron transfer of photosynthesis. [FeFe]-hydrogenases are a class of natural enzymes that can catalyze the reduction of protons to hydrogen in several microorganisms. In recent years, scientists focused on the biomimetic studies on chemistry of [FeFe]-hydrogenases. In view of these important theoretical and practical significances, we carried out studies on synthesis, structures and properties of a series of the new simple [FeFe]-hydrogenase models, porphyrin-fullerene dyads, porphyrin-fullerene-hydrogenase model triads. The main results obtained from this study are as follows:1. A total of 24 new compounds were successfully synthesized. Their structures were fully characterized by elemental analysis, IR, 1H NMR,31P NMR,13C NMR, HR-MS, UV-vis, Raman spectra, fluorescence spectra and electrochemistry. In addition, among them 12 compounds were characterized by X-ray diffraction analysis.2. Chapter two describes that 5-[4-C6H4COCH2CO2Et]-10,15,20-Ph3PorphH2 (1), the covalently-linked porphyrin-fullerene dyad 5-[4-C6H4C(O)=C(C60)CO2 Et]-10,15,20-Ph3PorphH2 (2),5-[4-C6H4COCH2CO2Et]-10,15,20-Ph3PorphZn (3) and 5-[4-C6H4C(O)=C(C60)CO2Et]-10,15,20-Ph3PorphZn (4) were obtained. The structure of 3 was determined by X-ray diffraction analysis. UV-vis spectra indicated no electron interaction between porphyrin and C6o in the ground state of 2 and 4. However, fluorescence spectra showed intramolecular electron transfer from the photoexcited ZnTPP moiety to C6o in the excited state of 2 and 4. It was found that molecular H2 was produced when Hg lamp was used to irradiate the aqueous solution consisting of electron donor EDTA,3, electron transfer mediator MV2+and catalyst colloidal Pt in the presence of HO Ac and surfactant Triton X-100.3. Chapter three describes that (4-C5H4N)C(0)=C(C6o)C02Et (1) and noncovalently-linked porphyrin-fullerene dyad (4-C5H4N)C(O)=C(C6o)C02Et-5, 10,15,20-Ph4PorphZn (2) were first synthesized via axial coordination as well as a known compound (C6H5)C(O)=C(C6o)C02Et (3) was obtained by the same procedures as 1. The structures of 2 and 3 were determined by X-ray diffraction analysis.1H NMR displayed the chemical shifts of 2 which were moved towards high fields relative to 1 due to the shielding effect of ZnTPP. UV-vis spectra indicated no electron interaction between porphyrin and C6o in the ground state of 2. However, fluorescence spectra showed intramolecular electron transfer from the photoexcited ZnTPP moiety to C6o in the excited state of 2. It was found that molecular H2 was produced when visible light was used to irradiate the aqueous solution consisting of electron donor EDTA,2, electron transfer mediator MV2+ and catalyst colloidal Pt in the presence of HO Ac and surfactant Triton X-100. Furthermore, H2 can be evolved when Hg lamp was utilized to irradiate the acetone/H2O solution consisting of electron donor EDTA,2, catalyst [FeFe]-hydrogenase model complex and proton donor HO Ac.4. Chapter four describes that (4-C5H4N)COCH2CO2CH2CH2OH (1), [(μ-SCH2)2N CH2CH2CO2H]Fe2(CO)6 (2), (4-C5H4N)C(O)=C(C60)CO2CH2CH2OH (3), [(4-C5H4N)C(O)=C(C6o)CO2CH2CH202CCH2CH2N(CH2S-μ)2]Fe2(CO)6(4)and [(4-C5H4N)C(O)=C(C60)CO2CH2CH2O2CCH2CH2N(CH2S-μ)2]Fe2(CO)6·5,10,15, 20-Ph4PorphZn (5) were first synthesized.1H NMR displayed the chemical shifts of 5 which were moved towards high fields relative to 4 due to the shielding effect of ZnTPP. Fluorescence tiltration showed intramolecular electron transfer from the photoexcited ZnTPP moiety to C60 in the excited state of 5.5. Chapter five describes that (i) treatment of [(μ-SCH2)2CH(OH)]Fe2(CO)6 with malonic acid gave [(μ-SCH2)2CHO2CCH3]Fe2(CO)6 (1) and [{(μ-SCH2)2CH}Fe2 (CO)6]2(O2CCH2CO2) (2). Further treatment of 2 with Me3NO·2H20 followed by addition of dppp (1,3-bis(diphenylphosphino)propane) or dppb (1,4-bis(diphenylphosphino)butane) yielded [{(μ-SCH2)2CH}Fe2(CO)5]4(O2C CH2CO2)2(Ph2PCH2CH2CH2PPh2)2 (3) and [{(μ-SCH2)2CH}Fe2(CO)5]2(O2CCH2 CO2)(Ph2PCH2CH2CH2CH2PPh2) (4), respectively. The structures of 1-4 were determined by X-ray diffraction analysis; (ii) [(μ-SCH2)2CH2]Fe2(CO)5 (Ph2PCH2CH=CH2) (5) was prepared by CO substitution through oxidative decarbonylation of the parent complex [(μ-SCH2)2CH2]Fe2(CO)6. Further treatment of 5 with Me3NO·2H20 afforded [(μ-SCH2)2CH2]Fe2(CO)4(Ph2PCH2 CH=CH2) (6). [(μ-SCH2)2CHO2CCH3]Fe2(CO)5(Ph2PCH2CH=CH2) (7), [(μ-SCH2)2CHO2CCH3]Fe2(CO)4(Ph2PCH2CH=CH2) (8) were obtained by a similar procedure. The structures of 5,6,7 were determined by X-ray diffraction analysis. Electrochemical studies demonstrated that 5 and 6 can catalyze proton to hydrogen in the presence of acid HOAc or CF3COOH; (iii) Reaction of [(μ-SCH2)2NCH2CH2CO2H]Fe2(CO)6 and (4-C5H4N)COCH2CO2CH2CH2OH afforded four products [(μ-SCH2)2NCH2CH2CO2CH2CH2OH]Fe2(CO)6 (9), [(μ-SCH2)2NCH2CH2CO2CH2CH2O2CCH2CH2N(CH2S-μ)2] [Fe2(CO)6]2 (10), [(μ-SCH2)2NCH2CH2CON(C6H11)CONHC6H11]Fe2(CO)6 (11) and [(μ-SCH2)2NCH2CH2CO2CH2CH2O2CCH2CO(C5H4N-4)]Fe2(CO)6 (12). The structures of 10 and 11 were determined by X-ray diffraction analysis. Furthermore, the formation mechanism of 11 was proposed. Electrochemical studies demonstrated that 11 can catalyze proton to hydrogen in the presence of acid HOAc.