A Fully Conjugated Planar Heterocyclic [9]Circulene.
Stephan K PedersenKristina EriksenS Evelyn StewartBoris F MinaevNataliya N Karaush-KarmazinOle HammerichGlib V BaryshnikovMichael PittelkowPublished in: Journal of the American Chemical Society (2020)
Fully aromatic [n]circulenes have only been known to encompass up to eight aromatic rings (n = 8), with no reports of endeavors in the synthesis of higher-order analogues (n > 8). Herein we present the first [9]circulene, formally a diazatrioxa[9]circulene, along with a tetrahydro-diazatetraoxa[10]circulene. The key transformation, for construction of the macrocyclic framework, is a simple high-yielding dimerizing condensation between 3,6-dihydroxycarbazole and glyoxal. Single crystal X-ray analysis reveals the [9]circulene to be perfectly planar and containing elongated benzene rings, which is induced by strain to accommodate planarity. Alternating bond lengths in the solid state indicate contribution from a [9]radialene resonance structure in the [9]circulene π-system. The central nonaromatic rings of both circulenes have paratropic ring currents, as evident by nucleus independent chemical shift (NICS) and anisotropy of the induced current density (ACID) calculations, which can be attributed to induced paratropicity from the surrounding aromatic rings.
Keyphrases
- solid state
- high glucose
- diabetic rats
- amino acid
- photodynamic therapy
- high resolution
- emergency department
- molecular dynamics simulations
- molecular dynamics
- magnetic resonance imaging
- molecular docking
- endothelial cells
- magnetic resonance
- oxidative stress
- energy transfer
- mass spectrometry
- quantum dots
- electronic health record