Potential molecular semiconductor devices: cyclo-Cn (n = 10 and 14) with higher stabilities and aromaticities than acknowledged cyclo-C18
The successful synthesis and isolation of cyclo-C18 in experiment mean the ground-breaking epoch of carbon rings. Herein, we studied the thermodynamic stabilities of cyclo-Cn (4 ≤ n ≤ 34) with hybrid density functional theory. When n = 4N + 2 (N is an integer), cyclo-Cn were thermodynamically stable. Especially, cyclo-C10 and cyclo-C14 were more thermodynamically, kinetically, dynamically, and optically stable compared with acknowledged cyclo-C18, and were the potential candidates of zero-dimension carbon rings. Cyclo-Cn (n = 10 and 14) show the similar molecular semiconductor characters to acknowledged cyclo-C18. The carbon atoms were sp hybridization in cyclo-C10, cyclo-C14, and cyclo-C18. Cyclo-C14 and cyclo-C18 had alternating abnormally single and triple bonds, but cyclo-C10 had equal bonds. Cyclo-C10, cyclo-C14, and cyclo-C18 with large aromaticities had out-plane and in-plane π systems, which were perpendicular to each other. The number of π electrons in out-plane and in-plane π systems, respectively, followed the standard Hückel aromaticity rule. Simulated UV-vis-NIR spectra indicated the similar electronic structures of cyclo-C14 and cyclo-C18.