ZfN: Search Results

1	Author	Pierre Hansen, Maolin Zheng	Requires cookie*
	Title	The Maximum Number of Kekule Structures of Cata-condensed Polyhexes
	Abstract	Let H denote a simply-connected cata-condensed polyhex. It is shown that if H has three hexagons in a row it does not have a maximum number of Kekule structures. Otherwise, its number of Kekule structures is equal to its number of sets of disjoint hexagons (including the empty set). These results lead to an efficient algorithm to determine simply-connected cata-condensed polyhexes with a maximum number of Kekule structures. A table of such values of H with up to 100 hexagons is provided.
	Reference	Z. Naturforsch. 48a, 1031—1038 (1993); received March 5 1993
	Published	1993
	Keywords	Polyhex, Cata-condensed, Kekule structure, Resonant set, Dualist graph
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	TEI-XML for	default:Reihe_A/48/ZNA-1993-48a-1031.pdf
	Identifier	ZNA-1993-48a-1031
	Volume	48

2	Author	TetsuoM. Orikawa	Requires cookie*
	Title	Graph-Theoretical Enumeration of Conjugated Patterns for Carbocyclic and Heterocyclic Compounds
	Abstract	An algorithmic analysis of the existence o f conjugated patterns for carbocyclic and heterocyclic com pounds is presented. This graph theoretical m ethod is applicable to the enumeration of Kekule patterns for hydrocarbon benzenoids, as a special case.
	Reference	Z. Naturforsch. 49a, 511 (1994); received June 22 1993
	Published	1994
	Keywords	Conjugated pattern, Cyclic com pound, Polygonal graph, Enumeration, Kekule structure
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0511.pdf
	Identifier	ZNA-1994-49a-0511
	Volume	49

3	Author	Ivan Gutman, SvenJ. Cyvin, Vesna Ivanov-Petrović	Requires cookie*
	Title	Topological Properties of Circumcoronenes
	Abstract	The regular-hexagon-shaped benzenoid hydrocarbons: B, = benzene (C 6 H 6), B 2 = coronene (C24H12), B 3 = circumcoronene (C 54 H 18), B 4 = circumcircumcoronene (C 15 oH 3 o), etc. possess unique topological properties. General expressions for the most important of such properties (number of fun-damental structural invariants, number of Kekule and Clar structures, number of aromatic sextets, Wie-ner and Szeged indices, spectral moments) are given, including a number of results that are communi-cated here for the first time. Cyclic conjugation in circumcoronenes is analyzed by means of its ener-gy-effect, and found to agree with the predictions of Clar's aromatic sextet theory only in the case of B[ and B 2 .
	Reference	Z. Naturforsch. 53a, 699—703 (1998); received April 4 1998
	Published	1998
	Keywords	Circumcoronenes, Benzenoid Hydrocarbons, Topological Properties (of Benzenoid Hydro-carbons), Kekule Structures, Clar Theory
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	TEI-XML for	default:Reihe_A/53/ZNA-1998-53a-0699.pdf
	Identifier	ZNA-1998-53a-0699
	Volume	53