Functional multicomponent hydrogen-bonded macrocycles

Abstract

Self-assembly can be defined as the generation of more complex species from simpler units through non-covalent interactions, being the hydrogen bonding one of the most used and useful tools for this purpose. A molecule that posses more than one binding site could form linear or cyclic structures. Those cyclic structures can be formed quantitatively due to cooperative effects, which provide a higher thermodinamic stability Modern supramolecular chemistry relies on the combination of diverse analytical techniques that can provide complementary information on complex self-assembly landscapes. Among them, resonance energy transfer, monitored by fluorescence emission spectroscopy, arises as a sensitive and convenient phenomenon to report binding intermolecular interactions. The use of molecular probes labelled with suitable complementary energy-transfer pairs can provide valuable information about the thermodynamics, kinetics and self-sorting characteristics of a particular self-assembled system. In the first chapter of the present Doctoral Thesis, we analyzed the noncovalent macrocyclization processes of dinucleosides by setting up a competition between intra- and intermolecular association processes of Watson-Crick H-bonding pairs. Furthermore, FRET probes were also used to examine the self-sorting phenomena between complementary dinucleoside monomers and to address the study of 2- and 3-component cyclic systems. On the other hand, in Chapter 2, we analyzed different kind of supramolecular isomerism in cyclic self-assembled structures. Thus, we examined the self-assembly process of dinucleosides that can freely alternate between different conformations, which resulted in the formation of isomeric forms of the macrocycle. We also analyzed the effect of changing the monomer configuration by means of an external stimulus, and the effect that this have in the self-assembly process.