Synthesis of polypeptides with asymmetric perylene diimide side chains

Perylenetetracarboxylic diimides (PDI) and their derivatives have been paid more attention due to their special photophysical and electrochemical properties. The modification on molecular structure of PDI aimed at changing the photophysical properties is one of an important means to obtain functional materials of PDI. An asymmetric PDI containing polypeptide chain at one imide nitrogen is synthesized by stepwise aminolysis reaction of 3,4,9,10-perylenetetracarboxylic dianhydride. The influence of reactions on yield is then inquired. The optimal reaction condition are determined as follows: molar ratio of PDI to cyclohexylamine, 1∶6; the solvent volume ratio of ethanol to water, 4∶1; reaction temprature and time, 70 ℃ and 6 h, the intermediate N-cyclohexyl-3,4,9,10-perylenetetracarboxylic-3,4-anhydride-9,10-imide. In the presence of the catalyst DMAP, this intermediate undergoing aminolysis reaction with L-Ala-D-Leu-(N-Me)-Ala-D-Leu-Ally affords polypeptides with asymmetric PDI in imidazole for 4 h at 120 ℃, and the tatal yield is above 32.6%. The product structure is characterized by ESI-MS and 1H-NHR. The process is simple and mild conditions, which provides a convenient synthetic route for the preparation of asymmetric PDI compounds.

Abstract licence: CC BY

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