Hybrid dithienylethene-naphthopyran multi-addressable photochromes: an ab initio analysis

Abstract

Using ab initio tools, we investigate the structural and electronic properties as well as the NMR spectra of hybrid dithienylethene-naphthopyran photochromes synthesised by Frigoli and Mehl (Angew. Chem. Int. Ed., 2005, 44, 5048). All possible closed/open structures have been considered and in each case several conformers could be characterised. Both UV/vis and NMR spectroscopic signatures have been compared to experimental references, and it was shown that the selected DFT/TD-DFT procedure is adequate not only to reproduce the measured spectral values but also to explain the observed photochromic pathways. Our work indicates that several conformers with different relative dithienylethene and naphthopyran orientations might be present experimentally.