Electron‐Transfer Processes in Zeolites and Related Microheterogeneous Media

Effect of Rotational Mobility on Photoelectron Transfer: Comparison of Two Zeolite Topologies

“…Thus, considerable effort is being made to understand the features that control electron-transfer dynamics. Toward that end, many donor−acceptor systems have been examined, and assembly of molecular units on microheterogeneous supports is being pursued to influence electron-transfer dynamics . By virtue of the nature of microheterogeneous supports, the motion of molecules is modified and it is of interest to examine how electron transfer is influenced by such immobilization.…”

“…Studies at 373 K (Figure 5b) showed no narrowing of line shape with respect to the 295 K spectrum (Figure 5a), indicating that motion is not induced at this increased temperature. 2 H NMR studies of Ru-EMT at room temperature (Figure 5d) indicate a sample with slight rotational mobility. By lowering the temperature to 200 K, it is possible to freeze out the rotational motion of Ru(bpy) 3 2+ resulting in a powder spectrum (Figure 5c) similar to that of room-temperature Ru-Y (Figure 5b).…”

“…Toward that end, many donor-acceptor systems have been examined, and assembly of molecular units on microheterogeneous supports is being pursued to influence electron-transfer dynamics. 2 By virtue of the nature of microheterogeneous supports, the motion of molecules is modified and it is of interest to examine how electron transfer is influenced by such immobilization. Zeolites, because of the molecular size of their cavities, are an excellent host system to investigate immobilization phenomena.…”

Uphill Photooxidation of NADH Analogues by Hexyl Viologen Catalyzed by Zinc Porphyrin-Linked Fullerenes

“…The spherical shape of C 60 , containing sixty delocalized π electrons, renders these carbon allotropes ideal components for the construction of efficient electron transfer model systems. Most importantly, the small reorganization energy, found for C 60 in electron transfer processes, results, on one hand, in an overall acceleration of the charge separation (CS) step, whereas on the other hand, a deceleration was noted for the energy-wasting charge recombination (CR) step. − Thus, efficient stepwise CS, for example, in fullerene-based dyad, triad, and tetrad ensembles, has been accomplished along well-designed and fine-tuned redox gradients. − The resulting high-energy CS state is converted into electrical energy by constructing integrated artificial photosynthetic assemblies on gold electrodes with the use of self-assembled monolayers (SAMs). , However, the conversion of the high-energy CS state in fullerene-containing donor−acceptor linked systems into chemical energy has yet to be reported, although there have been some reports on uphill photochemical reactions catalyzed by other photosensitizers. − …”

Charge Transport through a Novel Zeolite Y Membrane by a Self-Exchange Process

“…1 Our interests have been in the development of artificial photosynthetic systems, where light-activated charge separation can lead to interesting chemistry, including possibly the splitting of water into hydrogen and oxygen. 2 It is well recognized that in order to do so, the photogenerated hole and electron need to be spatially separated, and we are examining zeolite membranes toward this end. 3 Zeolitic membranes are an active area of research because of their molecular sieving ability.…”