scholarly journals Verifying the PCP-rule by five-center bond indices

2009 ◽  
Vol 74 (5) ◽  
pp. 549-554 ◽  
Author(s):  
Jelena Djurdjevic ◽  
Ivan Gutman ◽  
Robert Ponec
Keyword(s):  
Membered Ring ◽  
Energy Effect ◽  
Conjugated Hydrocarbons ◽  
Cyclic Conjugation ◽  
Bond Indices ◽  
Polycyclic Conjugated Hydrocarbons

According to the recently discovered PCP-rule, the (stabilizing) energy- effect of the cyclic conjugation in the 5-membered ring of acenaphthyleneand fluoranthene-type polycyclic conjugated hydrocarbons increases with the number of phenyl-cyclopentadienyl (PCP) fragments present in the molecule. It is now shown that the validity of the PCP-rule is also supported by the 5-center bond indices, an independent quantitative theoretical measure of cyclic conjugation in 5-membered rings.

scholarly journals Cyclic conjugation in benzo-annelated triphenylenes

2010 ◽  
Vol 75 (7) ◽  
pp. 943-950 ◽  
Author(s):  
Svetlana Jeremic ◽  
Slavko Radenkovic ◽  
Ivan Gutman
Keyword(s):  
Membered Ring ◽  
Electron Content ◽  
Strongly Correlated ◽  
Energy Effect ◽  
Cyclic Conjugation ◽  
Non Linear ◽  
Linear Manner

Cyclic conjugation in benzo-annelated triphenylenes was studied by means of the energy effect (ef) and the ?-electron content (EC) of the six-membered rings. A regularity that was earlier discovered in the case of acenaphthylene and fluoranthene congeners is now shown to hold also for benzo-annelated triphenylenes: Benzenoid rings that are annelated angularly with regard to the central six-membered ring Z0 of triphenylene increase the intensity of the cyclic conjugation in Z0, whereas linearly annelated benzenoid rings decrease the cyclic conjugation in Z0. The efand EC-values are strongly correlated, yet in a non-linear manner.

A theoretical study on a series of polycyclic conjugated hydrocarbons—dinaphthobenzo[1,2:4,5]dicyclobutadienes with tunable charge transport properties by controlling [N]phenylenes and (anti)aromaticity

2019 ◽  
Vol 7 (22) ◽  
pp. 6721-6727
Author(s):  
Hang Yin ◽  
Daoyuan Zheng ◽  
Yan Qiao ◽  
Xiaofang Chen
Keyword(s):  
Charge Transport ◽  
Transport Properties ◽  
Theoretical Study ◽  
Energy Gap ◽  
Conjugated Hydrocarbons ◽  
Polycyclic Conjugated Hydrocarbons

A multi-dimensional relationship founded on the targeted [N] number, the energy gap (Eg) and the aromatic degree was constructed for predicting cyclobutadienoid-containing dinaphthobenzo[1,2:4,5]dicyclobutadienes (DNBDCs) with better charge transport properties.

Topological Properties of Circumcoronenes

1998 ◽  
Vol 53 (8) ◽  
pp. 699-703 ◽  
Author(s):  
Ivan Gutman ◽  
Sven J. Cyvina ◽  
Vesna Ivanov-Petrović
Keyword(s):  
Regular Hexagon ◽  
Topological Properties ◽  
Benzenoid Hydrocarbons ◽  
Spectral Moments ◽  
Energy Effect ◽  
Cyclic Conjugation ◽  
Clar Structures ◽  
First Time ◽  
Structural Invariants

Abstract The regular-hexagon-shaped benzenoid hydrocarbons: B1 = benzene (C6H6), B2 = coronene (C24H12), B3 = circumcoronene (C54H18), B4 = circumcircumcoronene (C150H30), 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, Wiener and Szeged indices, spectral moments) are given, including a number of results that are communicated here for the first time. Cyclic conjugation in circumcoronenes is analyzed by means of its energy-effect, and found to agree with the predictions of Clar's aromatic sextet theory only in the case of B1 and B2.

scholarly journals Extremal octagonal chains with respect to the spectral radius

2018 ◽  
Vol 34 ◽  
pp. 356-372 ◽  
Author(s):  
Xianya Geng ◽  
Shuchao Li ◽  
Wei Wei
Keyword(s):  
Spectral Radius ◽  
Characteristic Polynomials ◽  
Conjugated Hydrocarbons ◽  
Polycyclic Conjugated Hydrocarbons ◽  
Chain Graphs

Octagonal systems are tree-like graphs comprised of octagons that represent a class of polycyclic conjugated hydrocarbons. In this paper, a roll-attaching operation for the calculation of the characteristic polynomials of octagonal chain graphs is proposed. Based on these characteristic polynomials, the extremal octagonal chains with n octagons having the maximum and minimum spectral radii are identified.

scholarly journals Phenyl-cyclopentadienyl rule

2012 ◽  
Vol 31 (1) ◽  
pp. 1 ◽  
Author(s):  
Jelena Đurđević ◽  
Ivan Gutman
Keyword(s):  
Membered Ring ◽  
General Regularity ◽  
Dft Methods ◽  
Carbon Bond ◽  
Ring Currents ◽  
Carbon Carbon Bond ◽  
Cyclic Conjugation ◽  
High Level ◽  
Derivatives Of ◽  
Ab Initio Dft

Within a systematic study of cyclic conjugation in the benzo-annelated derivatives of acenaphthylene and fluoranthene, a general regularity was discovered, named phenyl-cyclopentadienyl rule (PCP rule). According to this rule, six-membered rings connected to the five-membered ring by a single carbon-carbon bond increase the magnitude of cyclic conjugation in the five-membered ring. The greater the number of such six-membered rings is, the stronger the cyclic conjugation in the five-membered ring. The PCP rule was initially established by studying the energy effects of individual rings, and was eventually corroborated by a variety of other independent approaches (Wiberg bond orders, carbon-carbon bond lengths calculated by high-level ab initio DFT methods, multicenter delocalization indices, ring currents).

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