End‐substituted thiahelicenes for electronic device applications

Abstract

AbstractMinimum energy structures of neutral and radical cations of end‐substituted thia[n]helicenes (n = 1‐10) in DCM solvent are reported. For both neutral and radical cations of these helicenes, calculated structures are nonplanar for n = 3 to 10. Helical structures are obtained for higher helicenes, and the thia[8]helicene system has a helical structure with one complete turn. Equilibrium structures are predicted by using B3LYP‐D/6‐311++G(d,p) method in conjunction with the solvation model based on solute density. Single‐point energy calculations are also performed at the MP2 level to improve certain energy parameters. Excited‐state calculations are performed using time‐dependent density functional theory formalism to predict UV‐Visible spectra of neutral and radical cations of thia[n]helicenes in DCM solvent. Thia[n]helicenes radical cation have strong absorption in the near‐infrared region. Calculations also suggest that dimerization is not a favorable process in the DCM solvent for the end‐substituted neutral and radical cation of thia[7]helicene. The present theoretical study examines the molecular and electronic properties of thia[n]helicenes in search of near‐infrared electronic devices.