Dipeptides and their cyclized 2,5-piperazinedione (or diketopiperazine, DKP) derivatives
are attractive building blocks for supramolecular hydrogels. The Phe-Phe, (p-nitro)-Phe-Phe, and Phe-Val dipeptides and their corresponding DKPs are studied for
self-assembly in water. The DKPs were obtained in high yields by microwave-assisted
cyclization of the dipeptides in water, demonstrating that use of their methyl ester
derivatives as reported in the literature is not necessary for successful cyclization.
Single-crystal XRD structures are reported for two DKPs as well as stable hydrogels
at neutral pH.
Key words
dipeptide - diketopiperazine - self-assembly - hydrogels - amyloid - microwaves -
2,5-piperazinedione