Polycyclic aromatic hydrocarbons structural formulas

Figure 1. Structural formulae of polycyclic aromatic hydrocarbons.

The electronic properties and stability of PAHs depend not only on the size, but also markedly upon the arrangement of benzenoid rings. According to Clair s aromatic sextet rule, the stability of the isomers of certain polycyclic aromatics increases with the number of sextets. Thus, all-benzenoid polycyclic hydrocarbons (PBAHs) whose structure can be represented by a single Clar formula with no double bonds show extremely high stability, high melting point and low chemical reactivity. Some of them even exist in interstellar space [26]. A typical example is the hexa-peri-hexabenzocoronene (HBC, in Fig. 3.3) which has been studied since... [Pg.95]

Definition A generalized Clar structure of a polycyclic benzenoid hydrocarbon is a valence formula in which one or more aromatic Ji-sextets are inscribed in non-adjacent benzene rings such that the remaining part of the structure, obtained by deletion of benzene rings with sextets, must have a Kekule valence structure. [Pg.114]

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