14172-92-0Relevant articles and documents
Probing transient molecular structures with time-resolved pump/probe XAFS using synchrotron X-ray sources
Chen
, p. 161 - 174 (2001)
Laser pulse pump, X-ray pulse probe X-ray absorption fine structure (pump-probe XAFS) experiments using synchrotron sources are described from technical considerations and from scientific significance. There are three technical challenges of such experiments: (1) laser photoexcitation, (2) synchronization of laser pulse and X-ray pulse, and (3) detection; each of which is investigated in detail. Based on the results from these investigations, the transient molecular structure of a reaction intermediate produced by photoexcitation of NiTPP-L2 (NiTPP, nickeltetraphenylporphyrin; L, piperidine) in solution has been captured for the first time with the pump-probe XAFS on a 14-ns time scale obtained from the X-ray pulses from a third generation synchrotron source. The experimental results confirm that photoexcitation leads to the rapid removal of both axial ligands to produce a transient square-planar intermediate, NiTTP, with a lifetime of 28 ns. The transient structure of the photodissociated intermediate is nearly identical to that of the ground state NiTPP, suggesting that the intermediate adopts the same structure as the ground state in a non-coordinating solvent before it recombines with two ligands to form the more stable octahedrally coordinated NiTPP-L2. No detectable population of a penta-coordinated intermediate was present. This experiment demonstrates the feasibility of determining transient molecular structures in disordered media using the temporal resolution of a synchrotron X-ray source.
Insertion of Ni(I) into Porphyrins at Room Temperature: Preparation of Ni(II)porphyrins, and Ni(II)chlorins and Observation of Hydroporphyrin Intermediates
Peters, Morten K.,Herges, Rainer
, p. 3177 - 3182 (2018)
Reduced Nickel porphyrins play an important role as enzymatic cofactors in the global carbon cycle (cofactor F430), and as powerful catalysts in solar-to-fuel-processes such as the hydrogen evolution reaction, and the reduction of CO and CO2. The preparation of Ni(II)porphyrins requires harsh conditions, and characterization of the reduced species is intricate. We present a very mild, convenient, and high yielding method of inserting Ni into electron rich, and electron deficient porphyrins which at the same time gives access to to Ni(II) phlorins and Ni(II)chlorins and Ni(II)porphyrins.
Efficient oxidation of cumene to cumene hydroperoxide with ambient O2 catalyzed by metalloporphyrins
Shen, Hai M.,Ye, Hong L.,Wang, Qin,Hu, Meng Y.,Liu, Lei,She, Yuan B.
, p. 314 - 322 (2021/04/09)
A novel and efficient protocol for oxidation of cumene to cumene hydroperoxide was presented using ambient O2 catalyzed by very simple metalloporphyrins. The selectivity toward cumene hydroperoxide reached 98.3% in the cumene conversion of 28.1% with T(4-COOH)PPCu as a catalyst at 80°C. The origin of the higher performance of T(4-COOH)PPCu was mainly ascribed to the low catalytic performance of copper(II) in the cumene hydroperoxide decomposition, and the ability of T(4-COOH)PP in stabilizing cumene hydroperoxide through hydrogen-bond interactions between them. Compared with current industrial processes and academic research in oxidation of cumene to cumene hydroperoxide with O2, the main superiorities of this protocol were the high selectivity, high conversion, simple catalysts, solvent-free, additive-free and mild conditions which made this work an appealing reference for the industrial oxidation of cumene to cumene hydroperoxide, as well as the oxidative functionalization of other C-H bonds in various hydrocarbons. 2021 World Scientific Publishing Company.
Partial and full β-bromination of meso-tetraphenylporphyrin: Effects on the catalytic activity of the manganese and nickel complexes for photo oxidation of styrene in the presence of molecular oxygen and visible light
Esfandiar, Milad,Saadati, Saeedeh
, (2020/08/17)
A series of β-brominated meso-tetraphenylporphyrins, H2TPPBrx (x = 0, 4, 8) have been synthesized and the photocatalytic activity of their manganese (III) and nickel (II) complexes in photo oxidation of styrene was thoroughly investi
