Planar aromatic hydrocarbons

Figure 6.6 Excimer emission from crystalline planar aromatic hydrocarbons and types of crystal lattice.

Draw all isomers named methylnaphthalene (with a position number). Naphthalene, a planar aromatic hydrocarbon, has the structure,... 

The second planar aromatic hydrocarbon for which a more extensive investigation of adlayers fabricated by OMBD has been earned out is perylene. Especially the deposition on Cu(llO) substrates is of particular interest sinee this low symmetry surface may provide a useful template whieh rules out the formation of rotational domains in the initial stage of growth (as found for the case of pentacene on this substrate [52]). 

Rate Constants for O2 Queuching of Planar Aromatic Hydrocarbon... 

Those radical anions in which the charge is highly concentrated, and also dianions which can be produced from radical anions at more negative potentials, abstract hydrogen atoms rather indiscriminately from the solvent or quaternary ammonium cations. Tetraphenylallene and tetraphenylpropene radical anions protonate rapidly under conditions (O.IM BU4NCIO4 in DMF) where those of planar aromatic hydrocarbons are stable. Radical anion dimerisation reactions are not... 

It is known that certain planar aromatic hydrocarbons can intercalate between flat layers of hydrogen-bonded base pairs, causing distortion or forcing them to uncoil and causing errors in transcription (Figure 11.44a). Intercalation appears to be favoured by G-C rich portions of the DNA chain. 

Figure 6. Energy level scheme for a typical aromatic hydrocarbon. So denotes the electronic ground state, S the first excited singlet state and T the first excited triplet state. The triplet state is actually split into three sublevels by magnetic dipolar interaction of the triplet electrons (zero-field splitting). The dots and arrows denote the approximate populations and lifetimes of the sublevels for a typical, planar aromatic hydrocarbon. The lower panel shows schematically the time distribution of fluorescence photons (photoelectric pulses) for a single emitter undergoing singlet-tiiplet transitions leading to photon bunching.

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