Synthesis of Tribenzo[a,c,e]cyclooctene Oligomers: Toward Negatively Curved Nanocarbons

Abstract

Tribenzo[a,c,e]cyclooctene oligomers, which are potential precursors for synthesis of negatively curved nanographenes and nanobelts, have been designed and synthesized. The key to this synthesis is connecting 1,3‐di(4‐t‐butylphenyl)‐dibenzo[e,i]‐2H‐cyclopentacycloocten‐2‐one, dibenzo[3,4 : 7,8]cycloocta[1,2‐c : 5,6‐c′]difuran and the Sondheimer‐Wong diyne through Diels‐Alder reactions. As revealed by X‐ray crystallography, the trimer with a C8−C6−C8−C6−C8 backbone is shaped like a letter C in the crystalline state.

Reduction of π‐Expanded Cyclooctatetraene with Lithium: Stabilization of the Tetra‐Anion through Internal Li+ Coordination

“…[18] Furthermore, the saddle-shaped COT moiety is an important structural element for the construction of negatively curved carbon-rich compounds and carbon allotropes. [19,20] negatively curved nanocarbon has been reported, [21] along with a remarkable contorted chiral PAH with three embedded COT moieties having the shape of a monkey saddle. [22] However, the multi-electron accepting properties of π-expanded COTcontaining PAHs have not yet been investigated.…”

Recent advances and attempts in synthesis of conjugated nanobelts

“…The five‐membered rings in carbon nanobelts (e.g., the Schlüter belt) can induce positive curvature, while the seven‐ or eight‐membered rings in carbon nanobelts can induce negative curvature as demonstrated by two recently designed nanobelts shown in Figure 7. [ 61 ] These negatively curved carbon nanobelts also present key segments of Mackay crystals, [ 62,63 ] which are long‐sought‐after negatively curved carbon allotropes.…”

Reduction of π‐Expanded Cyclooctatetraene with Lithium: Stabilization of the Tetra‐Anion through Internal Li+ Coordination

“…Furthermore, the saddle‐shaped COT moiety is an important structural element for the construction of negatively curved carbon‐rich compounds and carbon allotropes [19, 20] . Recently, a unique COT‐containing molecular precursor towards negatively curved nanocarbon has been reported, [21] along with a remarkable contorted chiral PAH with three embedded COT moieties having the shape of a monkey saddle [22] . However, the multi‐electron accepting properties of π‐expanded COT‐containing PAHs have not yet been investigated.…”