Lay summary
Lead:DNA serves as a framework for the construction of well-defined structures on the nanometer scale. The formation and the properties of ordered aggregates of aromatic chromophores in a DNA duplex are investigated.Background:Arrays of various types of aromatic compounds can be generated by inserting segments of suitable derivatives into a DNA framework or by using the double helix as a scaffold for placement of appended chromophores. In addition to opening the way to novel types of materials with potentially useful spectroscopic, electronic or physical properties, oligonucleotide-chromophore conjugates may also lead to improved types of diagnostic tools. The rational formation of aromatic chromophore arrays is an intriguing challenge since ordered collectives of chromophores possess largely different properties than the individual molecules. Due to its repetitive and well-defined structural features DNA is a practical tool for the generation of nanometer-sized structures. Thus, the approach of using nucleic acids as a guiding frame for the formation of highly ordered chromophore assemblies has emerged over the past few years as a new research direction.Goals:Building upon the results obtained in the past with pyrene and related polyaromatic compounds, we are using DNA-chromophore conjugates for the assembly of multi-stranded architectures. The synthesis and evaluation of novel types of non-nucleosidic chromophores will be pursued. While we continue the investigation of additional types of pyrene derivatives we will extend our efforts to the synthesis of quinoxaline and porphyrin derivatives. The newly synthesized compounds will be evaluated for their stacking behaviour as well as their spectroscopic properties. Crucial aspects are the ability to assist hybrid formation, the fluorescence properties, and the compatibility with oligonucleotide synthesis. Additionally, we will extend our investigations of artificial helical systems formed by oligomers of pyrene and other building blocks. The amplification of chirality observed in a system composed of chiral and achiral oligopyrenes suggests that the oligomers undergo supramolecular polymerization. A further goal is the investigation of electron transfer through non-nucleosidic, aromatic building blocks.Significance:The use of DNA as an intelligent scaffold that allows the precise placement of functional molecules may open a way to novel types of materials with potentially useful spectroscopic, electronic or physical properties. In addition, oligonucleotide-chromophore conjugates may lead to improved types of diagnostic tools for the early detection of infective or genetic diseases.