Septulene: The Heptagonal Homologue of Kekulene

Abstract

Scheme 1. Septulene 1 and kekulene 2. The unique radial double bond in the KekulØ structure of 1 is indicated.

Topological characterizations on hexagonal and rectangular tessellations of antikekulenes and its computed spectral, nuclear magnetic resonance and electron spin resonance characterizations

“…Ever since the successful synthesis of kekulene, a molecule made by circumcision of coronene, several other holey analogs of kekulenes such as heptulenes, octulenes, and holey nanographenes in general, have been synthesized [5–7]. As these holey kekulene analogs possess very interesting and unusual properties not only from the standpoint of aromaticity, magnetism and so forth but also their pores facilitate sequestration and transport of metal ions and anions such as Cl$$$ {}^{-} $$$ [5–7]. Consequently, these materials have been studied from the standpoint of environmental remediation in addition to transport and sequestration of ions of various sizes.…”

“…Antikekulenes have posed considerable challenges and interest to synthetic chemists as all attempts to synthesize these antiaromatic compounds have failed up to now although their precursors have been successfully made in the lab [1–4]. Ever since the successful synthesis of kekulene, a molecule made by circumcision of coronene, several other holey analogs of kekulenes such as heptulenes, octulenes, and holey nanographenes in general, have been synthesized [5–7]. As these holey kekulene analogs possess very interesting and unusual properties not only from the standpoint of aromaticity, magnetism and so forth but also their pores facilitate sequestration and transport of metal ions and anions such as Cl$$$ {}^{-} $$$ [5–7].…”

Dianion and Dication of Tetracyclopentatetraphenylene as Decoupled Annulene‐within‐an‐Annulene Models

“…[1] Central to the interest in these molecules is the dichotomy about global delocalization of π electrons in two decoupled annulenoid forms (i.e., so‐called “annulene‐within‐an‐annulene” or AWA models) versus local delocalization to Clar's sextet (six‐membered rings each containing three pairs of electrons). Previous studies revealed the predominant contribution of the Clar's sextets structure over the AWA form, not only for kekulene [2] and corannulene [3] but also for their homologues, such as septulene, [4] octulene, [2b] [7]circulene, [5] and [8]circulene [5b, 6] analogues, all of which consist of fused six‐membered rings. Theoretical studies suggest that only molecules like [10,5]‐coronene (Figure 1), consisting of fused five‐membered rings, should have the AWA structures in which the outer and inner perimeters are completely decoupled [7] .…”

Facile Combustion Synthesis and Electrochemical Performance of the Cathode Material Li1.231Mn0.615Ni0.154O2

“…For kekulene as an archetypal [ n ]cycloannulene, a change in hub ring size changes the order of the cyclic graph, as exemplified in the synthesis of septulene by King and co‐workers (Figures 1 C and D). 8 Septulene’s computed saddle form, a minimum in a shallow well of the potential energy surface, undulates through pseudorotation and results in dynamic sevenfold symmetry; the specific bond lengths (experimental and computational) support a Clar electronic structure 9…”

“…In contrast to the above abuses, serious use of QM methods can lead to greater insight regarding the prediction of molecular properties 8. 20 Greater vigilance is needed to stem the tide of poor quality computational data.…”