Dicyclopenta[a,d]cyclooctene: A [14]Annulene Containing Two Zero-Atom Cross-Links

Abstract

14π‐Electrocyclization across the two pentafulvenoid moieties of pentafulvene 1 occurs upon heating to provide dicyclopenta[a,d]cyclooctene 2 [Eq. (1)]. The nonalternant hydrocarbon 2 shows diatropic character and a distinctive absorption spectrum with the longest wavelength maximum at 767 nm.

Singlet and Triplet Excited State Energy Ordering in Cyclopenta-Fused Polycyclic Aromatic Hydrocarbons (CP-PAHs) Suitable for Energy Harvesting: An Exact Model and TDDFT Study

“…It exhibits the longest wavelength absorption maxima (λ = 1375 (0.9) nm (eV)). 37 The calculated optical gap at highest D–A strength (|ϵ| = 5 eV) was found to be 0.7 eV, which is very close to the experimentally found absorption (0.9 eV) reported for the 2,7-di(tert-butyl) derivative of the DCPCO isomer. The TDDFT result of the optical absorption (1.0 eV) of DCPCO ( d ) is also in good agreement with experiments.…”

“…The 2,7-di­(terbutyl) derivative of the DCPCO ( d ) isomer is shown in Figure . It exhibits the longest wavelength absorption maxima (λ = 1375 (0.9) nm (eV)) . The calculated optical gap at highest D–A strength (|ϵ| = 5 eV) was found to be 0.7 eV, which is very close to the experimentally found absorption (0.9 eV) reported for the 2,7-di­(tert-butyl) derivative of the DCPCO isomer.…”

“…The TDDFT result of the optical absorption (1.0 eV) of DCPCO ( d ) is also in good agreement with experiments. The synthesis and optical absorption study of DCPCO isomer ( e ) was reported by Oda et al The UV/vis spectra of DCPCO isomer ( e ) shows the longest wavelength at 767 (1.61) nm (eV). The calculated value of optical gap of the above molecule is nearly 1.17 eV (0.73 Debye), whereas the TDDFT results show absorption at a comparatively higher energy of 2.67 eV with nonzero oscillator strength.…”

Renaissance of Annulene Chemistry

“…[14]Annulene ( 48 , Figure ) was first synthesized in 1960 by Sondheimer and Gaoni . Computational and experimental studies performed since have consistently concluded that the molecule adopts a nonplanar conformation with a delocalized π-bond structure in the solid crystalline state . The nonplanarity is ascribed primarily to nonbonding interactions between the internal protons.…”

7 Aromatic chemistry

“…118 Dicyclopenta[a,d]cyclooctene 88 was synthesized to investigate its aromatic nature as a [14]annulene containing two zero-atom cross-links. 119 Using Pdcatalysed coupling and/or an oxidative coupling reaction, di(6-azulenyl)acetylenes 89 (n = 1 and 2) were prepared. 120 The tripodal polyyne 90 was prepared by the reaction of 1,3,5-triethynylbenzene with 6-tert-butyl-1-iodo-3-(trimethylsilylethynyl)azulene.…”