The J-aggregation phenomenon of cyanine dyes has important commercial applications in the photographic industry. A typical cyanine dye was appended to poly-l-lysine in order to stabilize its J-aggregation
at the molecular level. Molecular modeling was used to provide information on the conformation of the
dye−polymer formed. Possible orientations of poly-l-lysine with cyanine dyes appended to it based on
molecular modeling calculations and physical measurements are discussed and evidence for a β-pleated
sheet conformation of the poly-l-lysine is shown. Also, for the first time J-aggregated monomer dyes and
dye−polymers are used to build layer-by-layer assemblies in combination with inorganic clay sheets. The
newly created architectures are used to fabricate three-dimensional structures on a solid support and have
potential applications in building layered systems for optical signal processing. Microscopy measurements
provide information about the organization of the J-aggregated cyanine dye−clay composites on solid
supports.
The dependence of the rate of electronic excitation transfer from a triplet donor (biacetyl) trapped inside a hemicarcerand cage to a range of triplet quenchers in free solution was studied as a function of the driving force and the internal reorganization energy of the acceptor, λ acceptor . Acceptors with internal reorganization energies ranging from ∼0 to more than 1.1 eV were investigated. It was found that quenchers with nearly identical triplet energies can lead to transfer rates differing by almost 3 orders of magnitude as a result of large differences in their ineternal reorganization energies. The data were analyzed in terms of the semiclassical Marcus-Jortner theory. Variable-temperature measurements were performed in order to independently evaluate the activation energies and thus to unequivocally determine which acceptors belong to the "normal" and which to the "inverted" Marcus region. Four distinct groups of triplet acceptors emerged from the analysis: (a) rigid aromatics with small geometry changes and modest internal reorganization energies; (b) acyclic olefins exhibiting a large-amplitude internal relaxation and correspondingly large reorganization energies; (c) cyclic olefins with exceptionally large λ υ values; and (d) molecular oxygen, O 2 , with negligibly small internal reorganization energy.
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