Polydiphenylenephthalide: Optical spectroscopy and DFT calculations

Abstract

The results of spectral and luminescent studies of polydiphenylenphthalide (PDF) solutions and thin films as well as molecule structure and its energy levels DFT modelling within the Gaussian-03 software package are presented. It is shown that structural unit (diphenylenephthalide) can form four polymer conformations with a similar energy gap. The most probable polymer conformation is the spiral cis-form with phthalide groups turned in opposite directions. At longwave optical transition the electronic density moves on a chain of a molecule from diphenyl part to somehow distant phthalide one. Fluorescence excitation spectra reveal a transition band on a long-wave tail of the absorption spectrum. Spectral and time measurements of the luminescence allow to assume the presence of conformation transformations of PDF molecule under its optical excitation.