Theoretical investigation on the spectroscopy prosperities of four isomers of an encoder molecule FGDTE

• The calculated stabilities of the isomers are in this order FGoDTEo > FGcDTEo > FGoDTEc > FGcDTEc.
• The absorption at 366 nm results the cyclization of both ring-open isomers of FG and DTE.
• The theoretical analysis explains the characteristics of the lowest-energy absorptions of FGDTE.
• The work provides some guides in encoder-molecule design.

A molecule consisting of one dithienylethene covalently linked to two fulgimide photochromes has been designed as a 4-to-2 encoder. The combined molecule has four stable isomers, one may convert to another by particular irradiations. In this paper, we calculated the Gibbs free energies of the four isomers and got the order of their stabilities. Then the mechanisms of ring-opening and ring-closing of the monomers were explored in detail and the reaction conditions for structural conversion were also discussed. The corresponding absorption spectra of the combined molecules were researched and the new characters in the designed systems were predicted as well. Finally, we optimized their corresponding excited-state structures and analyzed the emission properties.

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