Synthesis, Characterization and Oxygenation Reactions of meso-tetrakis(pentafluorophenyl)-N-confused-porphyrin Iron Complexes

• Main Authors: Kai-Chun Hsu, 許凱淳
• Other Authors: Ming-Che Chung
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/t7a98u

碩士 === 國立中央大學 === 化學學系 === 106 === The meso-tetrakis(pentafluorophenyl) N-confused porphyrin (NCTPFPP 1) was synthesized using literature method, and the other meso-tetrakis(pentafluorophenyl) N-confused oxo-porphyrin (NCTPFPOP 2) was firstly isolated and purified from the same reaction. Compound 2 was characterized by NMR and FT-IR spectroscopy methods, ESI-MS techinique and single-crystal X-ray diffraction determination to confirm a unique structure. Solvent-dependent tautomeric forms were studied on compounds 1 and 2. Compound 1 contains one amino NH proton and one inner C-H at an opposite site (2H form) in DMF, while compounds 2 has two amino NH and one inner C-H (3H form). The electron withdrawing and donating meso-substituents of N-confused porphyrin resulted in blue-shift and red-shift, respectively, on the UV-vis absorption spectrum. Cyclic voltammetery studies of 1 and meso-tetrakis(phenyl) N-confused porphyrin (NCTPP) were carried out to elucidate the positive shift on the redox potential for electron withdrawing meso-substituents of N-confused porphyrin. In the case of NCTPP, two reversible wave were observed on the positive side and one reversible and one half-reversible wave were oberserved on the negative side. In the case of 1, no reversible wave was observed on the positive side but two reversible wave were observed on the negative side. In addition, the NH chemical shift varied with concentration of 2 indicated the equilibrium between monmer and dimer. The iron complexes of meso-tetrakis(pentafluorophenyl) N-confused porphyrin, (HCTPFPPH)FeIIBr (1a) and (HCTPFPP)FeIIIBr (1b), were synthesized and characterized by 1H NMR, UV-vis spectra and single-crystal X-ray diffraction technique. The electron withdrawing meso-substituents of 1a resulted in blue-shift on the Soret band and Q band of UV-vis absorption spectrum, while the iron complex of meso-tetrakis(p-methoxylcarbonylphenyl) N-confused porphyrin with electron donating meso-substituent resulted in red-shift on the Soret band and Q band of UV-vis absorption spectrum. The 1a and 2a with electron withdrawing meso-substituents have less amount of peaks found in paramagantic 1H NMR spectrum than (HCTPPH)FeIIBr and (HCTPP)FeIIIBr. The oxidation rate of 1a is slower than (HCTPPH)FeIIBr, which correspond to proposed mechanism. In the proposed mechanism, losing electron is rate determining step. Cyclic voltammetery studies were carried out for 1a, 1b, (HCTPPH)FeIIBr, (HCTPP)FeIIIBr and (HCTPPO)FeIIIBr. There are two, one and two reversible waves in (HCTPPH)FeIIBr, (HCTPP)FeIIIBr and (HCTPPO)FeIIIBr, respectively. Furthermore, (HCTPPH)FeIIBr and (HCTPP)FeIIIBr have one elcetorn transfer in high potential redox processes and two electrons transfer in low potential redox processes. Besides, there are two and four reversible redox steps in 1a and 1b. Finally, we used (HCTPP)FeIIIBr, (HCTPPO)FeIIIBr, 1b and TPPFeIIICl as catalysts to activate dioxygen and compared oxygen atom transfer reactive activity with triphenylphosphine (PPh3). We found almost no triphenylphosphine oxide (OPPh3) product was produced when using TPPFeIIICl as catalyst and blank without any complex. However using N-confused Iron complexes as catalysts could produce OPPh3. In increasing order of reaction rate are (HCTPP)FeIIIBr, (HCTPPO)FeIIIBr and 1b. It means N-confused Iron complexes may undergo oxygen atom transfer reaction catalyzed by high valence FeV=O complexes intermediates during the reaction wih oxygen. In this process, 1b showed highest reactive activity with more stable and higher activity intermediate.