Sheet structure of an L,D-dipeptide aggregate: inclusion compounds of (S)-phenylglycyl-(R)-phenylglycine with amides.
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Abstrak
A simple dipeptide, (S)-phenylglycyl-(R)-phenylglycine (S,R-1), formed inclusion compounds with a small amide such as formamide, acetamide, N,N-dimethylformamide (DMF), or N,N-dimethylacetamide. By single-crystal X-ray analysis, the inclusion compounds were shown to have a wavy layer structure. The molecules of S,R-1 are arranged in parallel via ionic pairing of the carboxyl and amino groups to construct the wavy layers. The guest molecules were accommodated in a channel cavity between the layers by means of hydrogen bonding with (+)NH(3) of S,R-1. The cavity is surrounded by the phenyl groups of S,R-1 that conformationally rotate so as to make the cavity size fit the guest amide.