4,9- and 4,10-Substituted pyrenes: synthesis, successful isolation, and optoelectronic properties

We report herein a way to prepare and purify optoelectronic functional 4,9- and 4,10-substituted pyrene isomers. By tuning the size of substituents, the designed 4,9- and 4,10-isomers can be successfully isolated by recycling preparative size-exclusion chromatography (SEC) and/or repeated recrystallization. The structure and purity of the isolated compounds 1–5 have been confirmed by ¹H NMR, ¹³C NMR, and HRMS. The photophysical and electrochemical properties of compounds 1–5 have been studied in detail both experimentally and theoretically. The lowest transitions of these pyrenes, 1–5, are allowed, with moderate to high fluorescence quantum yields and radiative decay rates around 10⁸ s⁻¹. The differences between the electrochemical and photophysical properties of 4,9-, 4,10-, 1,6-, and 2,7-substituted isomers are compared and concluded.