Topological Characteristics of Strictly Pericondensed Constant-Isomer Benzenoid Series

Using the formula periodic table for benzenoids (Table PAH6 = Table 1 in [4]) and the excised internal structure concept, several new strictly peri-condensed series possessing an identical number of isomers have been identified [5]. Strictly peri-condensed benzenoids have the property that the graph spanned by their internal carbon vertices (i.e., their excised internal structure) is connected. Pyrene (C1 6H1 0) has ethene, coronene (C2 4H1 2) has benzene, and ovalene (C3 2H1 4) has naphthalene (C1 0H8) as excised internal structures and are strictly peri-condensed benzenoids that are members of the one-isomer series found in Tables 1 and 2. All constant-isomer strictly peri-condensed benzenoids are found on the extreme left-hand edge of Table PAH6 and are devoid of adjacent or proximate bay regions (fjords and coves). This translates into benzenoids with perimeters having everywhere two-carbon-atom gaps or greater, which means that all these even carbon strictly peri-condensed benzenoids can serve as excised internal structures for