Synthesis and characterization of [7]circulene

MP2 and DFT Calculations on Circulenes and an Attempt to Prepare the Second Lowest Benzolog, [4]Circulene

“…[5,[8][9][10] On proceeding from 3 to 5 the geometry of these hydrocarbons changes from a cuplike structure through a flat arrangement to a saddle-shaped geometry. Although various attempts to prepare the four-membered derivative 2 (see below) and a [7.7]circulene (in which ten contiguous benzene rings are fused around a central bicycloA C H T U N G T R E N N U N G [5.5.0]dodecane Abstract: MP2 and DFT calculations have been carried out for [n]circulenes for n = 3 to 20 in order to predict the strain energy and topology of these cyclically condensed aromatic systems.…”

“…Although various attempts to prepare the four-membered derivative 2 (see below) and a [7.7]circulene (in which ten contiguous benzene rings are fused around a central bicycloA C H T U N G T R E N N U N G [5.5.0]dodecane Abstract: MP2 and DFT calculations have been carried out for [n]circulenes for n = 3 to 20 in order to predict the strain energy and topology of these cyclically condensed aromatic systems. To synthesise [4]circulene (2), 1,5,7,8-tetrakis(bromomethyl)biphenylene (14) was prepared from the corresponding tetramethyl derivative (8) and subjected to various dehalogenation reactions; all attempts to obtain [2.2]biphenyl-A C H T U N G T R E N N U N G enophane (7) as a precursor for 2 by this route failed. Treatment of 14 with sodium sulfide furnished the thiaphanes 16 and 17, thermal and photochemical desulfurization of which also failed to provide 7.…”

“…While selected higher circulenes have been studied theoretically before (for example the [8]circulene (6, n = 2), [15] to the best of our knowledge this is the first systematic calculation on higher circulenes. Figure 2 shows the optimised structures of all circulenes studied: from [3]circulene (1) to [20]circulene (6, n = 14).…”

Thermal motion analysis in [5]-, [6]- and [7]-circulene crystals: a harmonic lattice-dynamical calculation

“…The structures of the three title compounds have been determined at different levels of accuracy over the years; the most recent data were obtained by X-ray diffraction for corannulene (Hanson & Nordman, 1976) at two different temperatures (203 and 293 K), fbr coronene (Fawcett & Trotter, 1965) at room temperature, and for [7]-circulene (Yamamoto et al, 1983(Yamamoto et al, , 1988, again at two temperatures (163 and 293 K). Neither disorder (Pawley & Rayment, 1979) nor rotational freedom (Boyd et al, 1974) seem to be present in the coronene crystal.…”

Heptagons in Aromatics: From Monocyclic to Polycyclic

“…The first member of the negatively curved heptagon-containing polycyclic arenes is [7]circulene, which was first synthesized by the Yamamoto group in 1983. [11] A few new examples of such negatively curved polycyclic arenes were reported recently.…”