Development of building blocks exhibiting self-sorting molecular recognition properties: towards coded self-assembly processes

Biology can achieve phenomenal information storage/processing capabilities from just four hydrogen bonding molecules. The orthogonal self-sorting of these four hydrogen bonding motifs is achieved alongside the hydrophobic collapse of the DNA backbone. Orthogonal self-sorting without the aid of a polymer backbone is di�cult to achieve, as shown by the minimal examples of self-sorting hydrogen bonding motifs available in the literature. This thesis describes the design, synthesis and binding studies of molecules that are capable of orthogonal self-sorting, without a preorganising backbone and begins to use them in a signalling cascade. In Chapter 2 ureidoimidazole, a conformer independent triple hydrogen-bond array, is introduced. Studies were carried out to investigate what effect, if any, preorganisation using intramolecular hydrogen bonding had on the binding affnity of triply hydrogen bonded complexes. Chapter 3 investigates another factor that can effect the binding affnity of complexes,the remote substituent effect. Two series of complementary molecules were synthesised so that they contained a variety of electron donating/withdrawing groups and the effect that these had on the binding affnity of the complex was measured. Chapter 4 describes a novel quadruple hydrogen-bond array, which was designed to interact strongly with its complementary partner. It was found that a combination of effects (differences in geometry and undesired conformers being favoured) lead to a low binding affnity being observed. Chapter 5 begins to investigate non-linear arrays, however none of those proposed were able to form heterodimers. Therefore a self-sorting system was assembled using a triple and quadruple hydrogen-bonded array. High fidelity interactions were achieved, even though it was possible to form undesired complexes. These undesired molecular interactions were exploited in Chapter 5, where a signalling cascade is described. Careful planning of the order in which to add the molecules can give different routes in which to achieve the self-sorting system, each with it's own fidelity trace. A photolabile tag was introduced to one of the molecules so that a photosensitive system could be achieved