Femtosecond fluorescence dynamics of zinc biphenylporphine in nanocrystalline TiO2 films: Evidence for interfacial electron transfer through space

Ultrafast Relaxation Dynamics in Zinc Tetraphenylporphyrin Surface-Mounted Metal Organic Framework

“…It is these effects (e.g., superradiance) which shorten the lifetimes of assemblies of coupled chromophors. Related phenomena were also detected in porphyrin J-aggregates and other multiporphyrin arrays. ,,− Since the structure of SURMOF is much more regular than that of J-aggregates, we presume that not only incoherent energy transfer (Förster mechanism) is responsible for the shortening of the fluorescence lifetimes of the S 2 and S 1 states, but also quantum coherent energy transfer. The latter mechanism is related to the electronic coherence (off-diagonal elements) of the density matrices of individual ZnTTPs comprising the SURMOF.…”

“…Time-resolved fluorescence Kerr gate spectroscopy with 10 fs time resolution was used in order to detect the S 2 quenching in porphyrin J-aggregates: τ S 2 = 1 ps, 130 fs, 360 fs, and τ S 1 = 40 ps . As a result of J-aggregation S 1 fluorescence quenching was also observed in zinc biphenylporphine/TiO 2 films . S 1 fluorescence quenching in zinc protoporphyrin (ZnPP) due to aggregation was also studied .…”

“…51 As a result of J-aggregation S 1 fluorescence quenching was also observed in zinc biphenylporphine/TiO 2 films. 55 S 1 fluorescence quenching in zinc protoporphyrin (ZnPP) due to aggregation was also studied. 56 Strong quenching of S 1 fluorescence was observed in multiporphyrin arrays, e.g., for Zn-free base and bis-Zn dimers τ S 1 = 23-210 ps.…”

“…Strong quenching of the excited states S 2 and S 1 was observed as a result of intramolecular S 1 –S 1 and S 2 –S 2 Förster energy transfer and charge transfer both in S 2 and S 1. ,− Both S 1 and S 2 fluorescence quenching in porphyrin J-aggregates was observed: − τ S 1 = 40–200 ps; τ S 2 = 130 fs to 1 ps.…”

Superior Grafting and State-of-the-Art Interfacial Electron Transfer Rates for Newly Designed Geminal Dicarboxylate Bound Ruthenium(II)– and Osmium(II)–Polypyridyl Dyes on TiO2 Nanosurface

“…Therefore, most likely, in the random mesoporous environment of the dye in the dye–TiO 2 solution, presumably the orientation of the dye is such that it parks one or both of the unsubstituted bipyridine moieties very close to the semiconductor surface such that electronic coupling of the excited state with the Ti 3d conduction band manifold is strong enough to mediate electron transfer through space or through bond by a superexchange tunnelling mechanism via appropriate orbitals of the intervening solvent molecules. Such through space electron injection has previously been postulated in the literature. − …”