Cyclo carbon (C 18 ) is a novel all-carboatomic molecule that has been generated and characterized recently . This allotrope of carbon has attracted considerable attention in the field of chemistry and material science since it has been observed in condensed phase , and a large number of theoretical explorations on its electronic structure , aromaticity , optical and spectroscopic properties , molecular interaction , potential applications in molecular devices , as well as multiple properties of its analogues have been reported in succession. However, there is currently no way to obtain an isolate product of C 18 and its pure-carbon analogues due to their extreme chemical activity.