Electronic structures and spectroscopy of sulfonated oligo(aryl ether ketones)

The proton conductivity of sulfonated poly(aryl ether ketones) (SPEK) has been found experimentally. A series of sulfonated oligo(aryl ether ketones) (SOEK) are designed so that the proton conductivity of SPEK can be simulated by the extrapolation. The electronic structures of SOEK have been investigated by using density function theory (DFT) at B3LYP/6-31G(d) level. The energy gaps of SOEK with the increasing aryl ketone units are decreased. The main absorption peaks in the electronic spectra of SOEK are gradually red-shifted with the extended conjugation. The chemical shifts of the carbon atoms connected with the sulfonic acid group in SOEK are changed upfield with the increase in the number of the aryl ketone units. The local aromaticity of the middle benzene ring in SOEK is decreased owing to the substitution of the linking atoms.