Remarkable Size Effect on Photophysical and Nonlinear Optical Properties of All-Carboatomic Rings, Cyclo[18]carbon and Its Analogues

Inspired by recent experimental observation of molecular morphology and theoretical predictions of multiple properties of cyclo[18]carbon, we systematically studied the photophysical and nonlinear optical properties of cyclo[2N]carbons (N=3-15) allotropes through density functional theory. This work unveils the unusual optical properties of the sp-hybridized carbon rings with different sizes. The remarkable size dependence of the optical properties of these systems and their underlying nature are profoundly explored, and the relevance between aromaticity and optical properties are highlighted. The extrapolation curves fitted for energy level of frontier molecular orbitals, maximum absorption wavelength, and (hyper)polarizability of considered carbon rings are presented, which can be used to reliably predict corresponding properties for arbitrarily large carbon rings. The findings in this study will facilitate the exploration of potential application of cyclocarbons in the field of optical materials.

Automated summary

This study systematically examined the photophysical and nonlinear optical properties of cyclo[2N]carbons (N=3-15) through density functional theory, revealing the unusual optical properties of sp-hybridized carbon rings with different sizes. The size dependence of optical properties, underlying nature, and the relationship between aromaticity and optical properties were explored. Extrapolation curves were presented to reliably predict corresponding properties for arbitrarily large carbon rings, facilitating the potential application of cyclocarbons in the field of optical materials.