Cubane and cubanoid: Structural, optoelectronic and thermodynamic properties from DFT and TD-DFT method

• Published in: Journal of molecular graphics & modelling 2021-03, Vol.103, p.107820-107820, Article 107820
• Main Authors: Barbosa, L.S., Moreira, E., Lopes, A.R., Fonseca, A.L.A., Azevedo, D.L.
• Format: Article
• Language: English
• Subjects: Cubane; Cubanoid; DFT and TD-DFT methods; Optoelectronic properties; Thermodynamic properties
• ISSN: 1093-3263; 1873-4243
• DOI: 10.1016/j.jmgm.2020.107820

In this paper, we report structural, electronic and optical properties of cubane (C8H8) and cubanoids (cubane-like molecules) using Density Functional Theory (DFT). The cubanoids are cubanes for which Carbon atoms have been substituted by Nitrogen (N), Phosphorus (P), Boron (B), Silicon (Si), Arsenic (As), Antimony (Sb) or Bismuth (Bi) atoms. These molecules presented exceptional stability with several different symmetry point groups, being the majority Td. All calculated vibrational frequencies are positive for any studied molecules indicating that all these structures are in a stable state. The HOMO-LUMO gaps and DOS were calculated converged towards to values between 1.87 eV and 5.61 eV, actually showing promising electronic properties (Just for comparison, the cubane energy gap is 7.50 eV). The optical absorptions were also calculated for the cubanoid structure using the Time-Dependent Density Functional Theory (TD-DFT). Their dependence on the wavelength is analyzed, where five of theses structures absorb on the visible region. Finally, the extrapolation of thermodynamic properties indicates that these cubanoid could be potentially synthesized spontaneously, where four structures, the synthesis would occur for temperatures below 400 K, while for Si4Bi4H4 structure, the synthesis would occur at room temperature. We report cubane based structures that present high stability, an estimated electronic gap ranging from 1.62 to 5.07eV. Their optical absorption dependence on the wavelength is analyzed and discussed, where five of theses structures absorb on the visible region of the light spectrum. and finally, their free energy indicates that several cubanoids could be spontaneously synthesized, where four structures, the synthesis would occur for temperatures below 400 K, while for Si4Bi4H4, the synthesis would occur at room temperature. [Display omitted] •All presented cubanoid molecules have exceptional stability. .•Five from the eight structures presented optical absorption on the visible region. .•The thermodynamic properties calculations indicate that all cubanoid could be synthesized. .