Orientation and Electronic Structures of Multilayered Graphene Nanoribbons Produced by Two-Zone Chemical Vapor Deposition

The orientation and electronic structure of multilayered graphene nanoribbons with an armchair-edge (AGNRs) were determined by low-temperature scanning tunneling microscopy in this study. The orientation of AGNRs was found to be an edge-on structure when positioned as a top layer, while previous reports showed a face-on structure for monolayered AGNRs on Au(111). According to density functional theory calculations, AGNRs in a top layer preferentially form as edge-on structures rather than face-on structures due to the balance of CH−π and π–π interactions between AGNRs. Scanning tunneling spectroscopy and density functional theory calculations revealed that the electronic structures of multilayered AGNRs are similar to those in a gas-phase due to the lack of interaction between AGNRs and the Au(111) substrate. The observation of AGNRs in mutilayers might suggest the conformation-assisted mechanism of dehydrogenation when there is no contact with the Au(111) substrate

Template Synthesis of Decaphyrin without <i>Meso</i>-Bridges: Cyclo[10]pyrrole

An acenaphthylene-fused cyclo[10]­pyrrole <b>1b</b> was selectively synthesized via an oxidative coupling reaction of the corresponding 2,2′-bipyrrole with the appropriate dianion template, croconate anion. The structure of <b>1b</b> as the isolated largest cyclo­[<i>n</i>]­pyrrole was elucidated by X-ray crystallographic analysis. The absorption spectrum exhibited a markedly red-shifted, intensified L band at 1982 nm, which was interpreted by application of Michl’s perimeter and Gouterman’s 4-orbital models, supported by magnetic circular dichroism (MCD) data and theoretical calculations

Template Synthesis of Decaphyrin without <i>Meso</i>-Bridges: Cyclo[10]pyrrole

An acenaphthylene-fused cyclo[10]­pyrrole <b>1b</b> was selectively synthesized via an oxidative coupling reaction of the corresponding 2,2′-bipyrrole with the appropriate dianion template, croconate anion. The structure of <b>1b</b> as the isolated largest cyclo­[<i>n</i>]­pyrrole was elucidated by X-ray crystallographic analysis. The absorption spectrum exhibited a markedly red-shifted, intensified L band at 1982 nm, which was interpreted by application of Michl’s perimeter and Gouterman’s 4-orbital models, supported by magnetic circular dichroism (MCD) data and theoretical calculations

Template Synthesis of Decaphyrin without <i>Meso</i>-Bridges: Cyclo[10]pyrrole

An acenaphthylene-fused cyclo[10]­pyrrole <b>1b</b> was selectively synthesized via an oxidative coupling reaction of the corresponding 2,2′-bipyrrole with the appropriate dianion template, croconate anion. The structure of <b>1b</b> as the isolated largest cyclo­[<i>n</i>]­pyrrole was elucidated by X-ray crystallographic analysis. The absorption spectrum exhibited a markedly red-shifted, intensified L band at 1982 nm, which was interpreted by application of Michl’s perimeter and Gouterman’s 4-orbital models, supported by magnetic circular dichroism (MCD) data and theoretical calculations