In this poster by Tauran et al we have described how various metal ions and supramolecular systems can modify the mechanical properties of DNA. Just how this happens is somewhat unclear. Certain systems can have no effect, others can soften DNA, others rigidify DNA and combinations of the last two types can massively rigidify DNA. Eviednetly our need is to understand the mechanism of such action and this requires a detailed knowledge of the structural nature of the possible complexes. To this end we have undertaken both search studies of the Cambridge Structural Database and also crystal structure determination of as many complexes as possible. In the poster we will describe: Firstly the existing structural data Secondly Crystal Growth experiments Thirdly Our recent solid state structural information Finally a minor detour will be taken on the influence of the surface chemistry of the crystal growth systems on the obtained polymorphs.