Cyanopolyynes in the Interstellar Medium: In Silico Analysis of Electronic Properties and Chain Length

Abstract

This study investigates electronic properties of linear cyanopolyynes (HCnN, with odd n from 3 to 29) by means of electron structure calculations at the DFT/B3LYP/6-311G(3df,3pd) level. Correlations between the chain length, the electric dipole moment and the HOMO-LUMO gap were analyzed. The molecular geometries were optimized and validated by vibrational calculations. The data obtained revealed that the dipole moment increases with the increase in chain length, while the gap decreases in a logarithmic way. The relationship between dipole and gap was described by by a potential model, indicating coherence between molecular structure and electronic properties. These patterns are relevant both for the detection of cyanopolyynes in the interstellar medium, by rotational spectroscopy, and for applications in molecular electronics. The statistical adjustments showed high coefficients of determination (R² > 0.99), confirming the robustness of the models used.