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.