ChemInform Abstract: LICHTABSORPTION VON FARBSTOFF‐MOLEKUELPAAREN IN SANDWICHSYST. AUS MONOMOLEKULAREN SCHICHTEN

Abstract

Auf hydrophoben Glasträgern werden monomolekulare Schichten der Cyaninfarbstoffe (I) bis (V) in Tripalmitin und Doppelschichten von Carbocyaninsalz (Va) (Z:O) auf Farbstoffe (I) (außer Y:S), Farbstoff (II) und Cyanin (III) sowie von Cyaninfarbstoffsalz (Ia) (Y:S) auf die Carbocyaninsalze (V) (außer (Va) (Z:O)) und Farbstoff (IV) aufgezogen.

Self-Assembly of Aromatic-Functionalized Amphiphiles: The Role and Consequences of Aromatic−Aromatic Noncovalent Interactions in Building Supramolecular Aggregates and Novel Assemblies

“…68 Energy minimization on a layer of 21 indicates that the global minimum is a translation layer with an area per molecule of 20.7 Å 2 , which is in good agreement with the measured value of 21 Å 2 . Similarly, calculation of the exciton shift for the aggregate corresponding to this structure by the extended dipole-extended dipole approximation of Czikkely, Foersterling, and Kuhn 33,34 gives a predicted λ max for the aggregate of 241 nm in reasonable agreement with the measured value of 244 nm. For this structure the separation between nearest neighbors is 4.10 Å, which is within the "magic distance" required for photodimerization in the crystal.…”

“…It is also possible to calculate excitonic splittings using the extended dipole-extended dipole treatment of Czikkely, Foersterling, and Kuhn. 33,34 Monte Carlo simulations for arrays such as those shown in Figure 2 indicate remarkable agreement between several of the measurable and predicted properties. From the experimental results and simulations discussed above we were able to propose a tetramer "pinwheel" as the basic structure of the aggregate.…”

“…The spectral shifts are ascribed to an excitonic splitting associated with a "card pack" array of transition dipole moments as developed in the approaches of Kasha and Hochstrasser 32 and Czikkely, Foersterling and Kuhn. 33,34 Although the aggregates formed in films at the airwater interface are rather resistant to dilution, aqueous dispersions of pure SPLs may be diluted by treatment with a large excess of dispersions of aqueous saturated phospholipids such as dimyrystoyl phosphatidyl choline (DMPC) or dipalmitoylphosphatidyl choline (DPPC) at temperatures above the phase-transition temperatures of both the saturated phospholipid and the SPL. [29][30][31] The dilution is characterized by several spectral isosbestic points, suggesting a direct conversion of the aggregate to dimer (or monomer, depending upon whether a SPL with one or two trans-stilbenes was examined) without evolution through several spectrally distinct aggregated species.…”

3,3′,5,5′-Tetrabromo-4,4′-dihydroxybiphenyl

“…Within these stacks, the distance between the planes (defined by the C atoms in the benzene rings) is 3.526 (3) Å . This value is close to the distance of 3.49-3.54 Å between 3,3 0 ,5,5 0 -tetrachloro-4,4 0 -dihydroxybiphenyl molecules (McKinney & Singh, 1988) and of 3.54 Å between the planes in layered aromatic hydrocarbons (Czikkely et al, 1970), thus suggesting the presence of interactions between 3,3 0 ,5,5 0 -tetrabromo-4,4 0 -dihydroxybiphenyl molecules. Despite these intermolecular interactions, (I) does not adopt a planar conformation in the crystalline form.…”

Mapping the orientation of exciton transition dipoles along individual nanostructures of molecular J-aggregates

“…Of the various structural models proposed to account for the spectral properties 3-5 only the so-called brickstone arrangement gives satisfactory results for the observed amount and polarity of the spectral shift when extended dipole model is used for the calculation of intermolecular interaction energy within the aggregate. 6 In the brickstone model 3 individual molecules are aligned in an alternating fashion with their long axes approximately parallel to each other and with large lateral displacements of the adjacent molecular centers. Based on this model, the narrow linewidth of the spectrum has been explained as a result of motional narrowing of delocalized Frenkel exciton states with large coherent length in 1-dimensional ͑1D͒ molecular chains.…”