نتایج جستجو برای: benzenoid systems

تعداد نتایج: 1183720  

2011
Jianguang Yang Fangli Xia Hongyan Cheng H. Y. Cheng

The atom-bond connectivity (ABC) index is a recently introduced topological index, defined as ABC(G) = ∑ uv∈E(G) √ du+dv−2 dudv , where du (or dv) is the degree the vertex u (or v). The ABC index of benzenoid systems and phenylenes are computed, a simple relation is established between the atom-bond connectivity index of a phenylene and the corresponding hexagonal squeeze in this paper. Mathema...

2012
Thomas A. Colquhoun Danielle M. Marciniak Ashlyn E. Wedde Joo Young Kim Michael L. Schwieterman Laura A. Levin Alex Van Moerkercke Robert C. Schuurink David G. Clark

Floral volatile benzenoid/phenylpropanoid (FVBP) biosynthesis is a complex and coordinate cellular process executed by petal limb cells of a Petunia×hybrida cv. 'Mitchell Diploid' (MD) plant. In MD flowers, the majority of benzenoid volatile compounds are derived from a core phenylpropanoid pathway intermediate by a coenzyme A (CoA) dependent, β-oxidative scheme. Metabolic flux analysis, revers...

2006
Ivan Gutman Bojana Borovićanin

An explicit combinatorial expression is obtained for the Zhang-Zhang polynomial (also known as “Clar cover polynomial”) of a large class of pericondensed benzenoid systems, the multiple linear hexagonal chains Mn,m. By means of this result, various problems encountered in the Clar theory of Mn,m are also resolved: counting of Clar and Kekulé structures, determining the Clar number, and calculat...

1982
Alexandru T. Balaban

Five theoretical and/or experimental problems involving benzenoid polycyclics and related eystems are discussed. The dualiet graph characterizes uniquely any polycyclic aromatic hydrocarbon (PAH or pol.yhex), and differentiates between catafusenes, perifusenes and coronafusenes (catahexes, perihexes, coronahexes). 1. The topology of catafusenes, expre8sed by their dualist graphs, can be correla...

Journal: :Journal of Synthetic Organic Chemistry, Japan 1959

2018
I. Gutman

Two empirical rules are formulated for the topological resonance energy (TRE) of benzenoid hydrocarbons: (a) TRE is roughly linear function of the number of Kekule structures, and (b) in a homologous series containing a linear polyacene fragment, TRE is a linear function of the length of this fragment. In certain cases, however, the TRE model leads to incorrect predictions. There exist pairs of...

Journal: :Discrete Mathematics 2006
Khaled Salem Sandi Klavzar Ivan Gutman

The resonance graph R(B) of a benzenoid graph B has the perfect matchings of B as vertices, two perfect matchings being adjacent if their symmetric difference forms the edge set of a hexagon of B . A family P of pair-wise disjoint hexagons of a benzenoid graph B is resonant in B if B−P contains at least one perfect matching, or if B − P is empty. It is proven that there exists a surjective map ...

2010
Ivan Gutman

Fluoranthenes are polycyclic conjugated molecules consisting of two benzenoid fragments, connected by two carbon–carbon bonds so as to form a five-membered ring. Fluoranthenes possessing Kekulé structures are classified into three types, depending on the nature of the two carbon–carbon bonds connecting the two benzenoid fragments. Either both these bonds are essentially single (i. e., single in...

Journal: :Faraday discussions 2007
Patrick Bultinck

A large number of local aromaticity indices for the benzenoid rings in polyaromatic hydrocarbons is computed. The results are interpreted, supporting Clar's hypothesis, and mutual correlations are investigated. It is shown that there are good correlations between all indices that strictly allow comparing benzenoid character. Poor correlations are found with NICS. A rationale is offered, yieldin...

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