Excited-State Dynamics of 5,10,15,20-Tetraphenyl- 21H,23H-porphine Manganese(III) Chloride Encapsulated in TiMCM-41 and MCM-41; Proved by fs-Diffuse Reflectance Laser Photolysis

Abstract

5,10,15,20-Tetraphenyl-21H,23H-porphine manganese(III) chloride (MnIIITPP(Cl)) was encapsulated into MCM-41 and TiMCM-41, and its photoinduced electron transfer had been studied by using femtosecond diffuse reflectance photolysis. Two different transient species (c.a. 10 ps and c.a. 80 ps) were observed. The shorter-lived species should be originated from relaxation of a “tripmultiplet” state and the longer-lived species should be attributed to the spin-forbidden relaxation (slower than the spin-allowed decay of triptquintet) via a quintet CT state. After irradiation, MnTPPCl+• radicals are detected in MCM-41 or TiMCM-41, indicating that the mesoporous silicate framework plays a good electron acceptor. Furthermore, it has been found that the formation MnTPPCl+• is easier in TiMCM-41 than in MCM-41, indicating that framework modification by incorporating the Ti4+ into the MCM-41 enhances the electron-accepting ability of the MCM-41 framework.

Photocatalytic Oxygenation of Substrates by Dioxygen with Protonated Manganese(III) Corrolazine

“…A “tripmultiplet” manifold ( 3 T 1 , 5 T 1 , 7 T 1 ) is derived from the lowest ring (π,π*) triplet. 55 Femtosecond laser excitation of 1 leads to a new maximum absorption at 610 nm, which can be assigned to the tripquintet ( 5 T 1 ) excited state (Figure 6). The absorption due to the tripquintet ( 5 T 1 ) decayed in a few ps with a rate constant of 3.1 × 10 9 s −1 , and there was no effect of O 2 on the rate due to the fast intersystem crossing to the tripseptet excited state ( 7 T 1 ) of 1 with a longer lifetime (Figure 6).…”

Electron injection dynamics in dye-sensitized semiconductor nanocrystalline films

“…These techniques have been applied successfully to powder samples like organic crystals and semiconductor particles, and made understanding of photochemistry in solids deeper [93][94][95][96][97][98][99][100][101][102][103][104]. We here utilized this technique to reveal photo-induced interfacial electron transfer dynamics in dye-sensitized solar cells under operational conditions, performance of which had been characterized beforehand.…”

Chemistry in Confining Reaction Fields with Special Emphasis on Nanoporous Materials

“…There were several reports describing the enhanced stability of radicals in silica mesopores studied by EPR spectroscopy, for instance during polymerisation reactions, [85] on surfaceconfined ketyl radicals [86] and during photoinduced charge separation. [87] However, in the opposite case, if suitable reaction partners are present, the chances for a reaction of these partners are greatly enhanced inside a CRF. This last type of behaviour was demonstrated in a very elegant study in 2005; HOC radicals were generated by radiolysis and were then trapped by the profluorescent compound coumarin.…”