e-Purine Amino Acids in Sequence-Specific, Self-Folding Architectures Ronald K. Castellano, Department of Chemistry, University of Florida The design of wholly synthetic molecules that adopt well-defined structures in solution challenges our understanding of molecular programming, and leads to novel materials properties. We have prepared and rigorously characterized 12 new donor–acceptor purines (right) as building blocks for information-rich synthetic architectures. These molecules, unlike natural nucleobases, boast remarkable optical properties in solution that make them useful in a variety of sensing and materials applications. D1, D2 A = CO2CH3 NH2, H NH2, N(CH3)2 N(CH3)2, OBn N(CH3)2, N(CH3)2 N(CH3)2, NH2 N(CH3)2, H FF = 0.42 FF = > 0.95 FF = 0.90 FF = >0.95 FF = 0.81 fluorescence emission data (CH2Cl2) FF = 0.2 to unity tF = 0.5 to 7.5 ns Recognizable for the donor–acceptor purines is that when D1 = NH2 and A = CO2H a new amino acid is created. These amino acids should merge the most exciting chemical properties of amino acids and nucleobases into one building block. We have successfully prepared one derivative and demonstrated its subsequent amide bond formation. We are poised to prepare hybrid peptide structures of e-purine amino acids and conventional a-amino acids; a model of one is shown at the left. In solution these oligopeptides should fold into well-defined conformations, like helices, much in the same way that proteins and DNA do.