Archicarbons: New Carbon Allotropes Build from Circular Arches of Carbon Atoms as Building Blocks

Abstract

Molecular and periodic allotropes based on cyclo[18]carbon, known as archicarbons, were investigated using density functional theory (DFT) in both molecular and periodic models. This study explores the physicochemical characteristics of these exquisite carbon allotropes, including various molecular archicarbons (spiro[18]carbon, bicyclo[8]carbon, 0-tricyclo[8] carbon, 0-bi(cyclo[19]carbon), 1-bi(cyclo[19]carbon), and 0-fused[18]carbon) and periodic archicarbons (poly-spiro[8]carbon, poly-0-bi(cyclo[8]carbon), poly-1-bi(cyclo[8]carbon)). Most proposed molecular archicarbons showed higher cohesive energy than cyclo[18]carbon, except for bicyclo[8]carbon, which suggests that those may be experimentally observable. Proposed synthetic routes for both molecular and periodic archicarbons are suggested, highlighting their potential, particularly in semiconductor applications, and paving the way for further exploration of their distinct electronic properties.