Structure-aromaticity-spectroscopy relationship in conjugated polymers

In this study, an effort has been made to analyze the aromaticity of oligomers of phenylenes and thiophenes, with the presence and absence of linkers using Nucleus-Independent Chemical Shift (NICS) as a descriptor. The relation between HOMO–LUMO gaps, reorganization and excitation energies with respective NICS values has been employed to develop a structure-aromaticity-conjugation spectroscopy relationship (SACSR). Results show that HOMO–LUMO gaps/excitation energies of various model systems exhibit linear relationships with the inverse of the NICS values, indicating the possible existence of the SACSR.