Di(alkoxy)- and di(alkylthio)-substituted perylene-3,4;9,10-tetracarboxy diimides with tunable electrochemical and photophysical properties

Nucleophilic substitution of N,N′-dicyclohexyl-1,7-dibromoperylene-3, 4:9,10-tetracarboxydiimide (PTCDI) with an excess of corresponding alkanol in the presence of sodium hydride or anhydrous potassium carbonate at 85-100 °C provided both di(alkoxy)- and mono(alkoxy)-substituted PTCDI compounds, namely, N,N′-dicyclohexyl-1,7-di(alkoxy)perylene-3,4:9,10-tetracarboxydiimide (3) and N,N′-dicyclohexyl-1-bromo-7-alkoxyperylene-3,4:9,10- tetracarboxydiimide (2). Starting from mono(alkoxy)-substituted PTCDI, nucleophilic substitution with thiol, thiophenol, or alkylamine led to the formation of unsymmetrical 1,7-di(substituted) PTCDI compounds (7-10). For the purpose of comparative studies, symmetrical di(substituted) N,N′- dicyclohexyl-1,7-di(alkylthio)perylene-3,4:9,10-tetracarboxydiimide (4), N,N′-dicyclohexyl-1,7-di(thiophenyl)perylene-3,4:9,10-tetracarboxydiimide (5), and N,N′-dicyclohexyl-1,7-di(alkylamine)perylene-3,4:9,10- tetracarboxydiimide (6) have also been prepared by a similar nucleophilic substitution. These newly prepared PTCDI compounds have been characterized by a wide range of spectroscopic methods in addition to elemental analysis. Electronic absorption and fluorescence studies revealed that the absorption and emission bands as well as the fluorescence quantum yield can be tuned continuously over a large range by incorporating substituents with different electron-donating abilities.