Let H be a hexagonal system. The Z-transformation graph Z(H) is the graph where the vertices are the perfect matchings of H and where two perfect matchings are joined by an edge provided their symmetric difference is a hexagon of H (Z. Fu-ji et al., 1988). In this paper we prove that Z(H) has a Hamilton path if H is a catacondensed hexagonal system. A hexagonal system [ll], also called honeycom...

Fibonacenes (zig-zag unbranched catacondensed benzenoid hydrocarbons) are a class of polycyclic conjugated systems whose molecular graphs possess remarkable properties, often related with the Fibonacci numbers. This article is a review of the chemical graph theory of fibonacenes, with emphasis on their Kekulé–structure–related and Clar–structure–related properties. ————————————————— ∗Supported ...

The distance d(u, v|G) between the vertices u and v of a molecular graph G is the length of a shortest u, v-path. We consider a class of Wiener–type topological indices Wλ(G) , defined as the sum of the terms d(u, v|G) λ over all pairs of vertices of G . Several special cases of Wλ(G) , namely for λ = +1 (the original Wiener number) as well as for λ = −2,−1,+1/2,+2 and +3 , were previously stud...

(24) Ritter, G. L.; Isenhour, T. L. Minimal Spanning Tree Clustering of Gas Chromatographic Liquid Phases. Comput. Chem. 1977, 1, 145-153. Everitt, B. Cluster Analysis; Halsted: New York, 1974. Balaban, A. T. Chemical Graphs. XXXIV. Five New Topological Indices for the Branching of Tree-Like Graphs. Theor. Chim. Acra 1979, 53, 355-375. Balaban, A. T.; Motoc, I. Chemical Graphs. XXXVI. Correlati...

The non-benzenoid aromatic D(5h) and enediolate C(2v) form of C5O5(2-) have been stabilized by hydrogen bonding with urea and 1,3-dimethylurea, respectively, in the host lattices of two novel crystalline inclusion compounds.

Non-alternant non-benzenoid hydrocarbons exhibit very different optical and electronic properties than their well-studied benzenoid analogues. However, preparing such structures with extended conjugation length, remains challenging. Herein, we report the synthesis of azuleno[2,1,8-ija]azulene derivatives using a two-step sequence involving four-fold aldol condensation between aromatic dialdehyd...