Triplet-state photophysics of naphthalene and .alpha.,.omega.-diphenylpolyenes included in heavy-cation-exchanged zeolites

Triplet states and optical absorptions in finite polyenes and conjugated polymers

“…This can affect the interpretation of numerical results on small-sized systems, at least for weak coupling. Second, for (forbidden) optical transitions between the singlet ground state and the triplet state -such as would be visible in the high resolution spectroscopy [3) or in the "spectroscopic matrices" [4] -one would expect to observe the unrelaxed form of the triplet state because of the essentially instantaneous nature of the transition. However, for allowed triplet-triplet transitions -as seen in any of the photoinduced measurements -the relaxed triplet state should be play the role of the initial state.…”

“…In finite polyenes, earlier work using pulse radiolysis and flash photolysis [1, 21 to observe the very weak (forbidden) singlet-triplet in addition to the (allowed) triplet-triplet transitions has be supplemented by the results of ultra high resolution spectroscopy [3] and of embedding the polyenes in " spectroscopic matrices" [4] which enhance the forbidden transitions. In conducting polymers, novel experimental techniques including "optically detected magnetic resonance" (ODMR) [5,6,7, 81, photcinduced ESR [9], and "spin-dependent photomodulation" (SDPM) [10,11] have begun to produce definitive information on the location-and properties of triplet excitations.…”

Metal Complexes Supported on Solid Matrices for Visible‐Light‐Driven Molecular Transformations

“…[11] Various physical and chemical properties, such as electrostatic potential and electric field within the supercage, and the restricted space available for encapsulated guest molecules are systematically controlled by changing the aforementioned extraframework metal cations. [12] Following pioneering research by the groups of Turro [13] and Ramamurthy, [14] many studies concerning the effect of microenvironment on the photochemical and photophysical behaviors of guest molecules have been carried out. Interestingly, phosphorescence emission of organic dyes can be induced within heavy cation-exchanged zeolites.…”

Controlling Photoreactions Through Noncovalent Interactions Within Zeolite Nanocages

“…10.4 ). 14, 15 Results obtained with azo compounds supports the expectation that a zeolite could also infl uence ISC between an n π * singlet and an n π * triplet. Numerous studies on azo compounds have established them to possess very poor ISC and not phosphoresce at 77 K even in the presence of a heavy -atom perturber.…”

“…Heavy -atom -induced phosphorescence that allows the Li + X Tl + X Cs + X use of ODMR in zero applied magnetic fi eld, has provided information on the geometry of the alkali metal ion -aromatic (naphthalene) interaction in zeolites. 15 The sublevel -specifi c dynamics for adsorbed naphthalene show a distinct increase in relative radiative character and total rate constant of the out -of -plane x -sublevel with increasing mass of the cation perturber. Once again, ODMR kinetic results suggest naphthalene to be adsorbed through its π -cloud at a cation site (cation -π interaction 6 ).…”