Bay- and peri-functionalized donor-acceptor perylene monoimides via nitration and nucleophilic substitution/reduction pathway

The positions of electron-releasing and withdrawing groups on perylene monoimides (PMIs) have an important effect on the photophysical properties. In general, modification of the parent PMI dye is carried out on bromo-PMIs; however, these precursors offer limited structural diversity on account of the regioselectivity of bromination reactions used for their synthesis. Therefore, the synthesis of PMIs inaccessible by means of bromo-PMIs is a very important task in improving the photophysical properties and application potentials of this class of fluorescent dyes. In an effort to develop an alternative approach for the construction of PMI-based push-pull systems, here, we present the introduction of different donors of varying electron-donating strength at 1-, 9-, 1,9-, and 9.10- positions of the PMI core by performing nucleophilic aromatic substitution or reduction on the corresponding nitro-PMIs as starting materials. Detailed photophysical characterizations together with theoretical calculations explain the unprecedented fluorescence properties that occur in target compounds depending on the nature and position of the substituent groups.