Absorption to and emission from the excited electronic state 1¹Bu in long linear all‐trans‐polyenes: The case of ttbP9 and ttbP11

Abstract

A 1:1‐mixture of decalin and methylcyclohexane (v/v), generates a solvent mixture that allows measurements at temperatures as low as 77 K of the emission and absorption spectra of long‐chain linear polyenes. This solvent mixture, on lowering the temperature also generates interesting increases in polarizability and viscosity that undoubtedly facilitate the study of these important compounds. In this study, we show that the two polyenes studied, ttbP9 and ttbP11, generate photophysical behavior that can be explained by the presence of their excited 11Bu state, as the first excited electronic state. Consequently, the solvatochromism of the absorption and the emission of these two polyenes are equally sensitive to the polarizability of the solvent used. We must also point out that the absorption and emission spectra of ttbP9 and ttbP11, whose molecular structures have a long polyene chain, do not show Stokes shift. This is especially relevant when it is commonly accepted that polyene compounds have a Stokes shift that increases with the length of their polyene chain.