Photodimerization in pyrimidine‐substituted dipeptides

Ten N ε ‐glycylornithineamide derivatives have been synthesized containing various N α ‐linked pyrimidine‐1‐ylacetyl groups which can undergo (2π + 2π) photodimerization on irradiation with UV light at 254 nm. The dimerization efficiency of the free and bound pyrimidine groups was compared in aqueous solution: it was dependent on the substitution of the pyrimidine ring. N α , N α′ ‐bis‐(uracil‐1‐ylacetyl)‐( N ε ‐glycylornithineamide) and N α , N α′ ‐bis‐(5‐bromouracil‐1‐ylacetyl)‐( N ε ‐glycylornithineamide) were identified as possible candidates for optical data storage. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd.