The work contained in this thesis deals with the synthesis of supramolecular responsive decorated receptors based on calixarene and calixpyrrole architectures. One of the aims of the thesis was to assemble responsive H-bonded dimeric capsules. In order to achieve this, ureas were incorporated in the receptor’s scaffolds. In this thesis the assembly of supramolecular H-bonded capsules is investigated by means of NMR spectroscopy.
We explored the self-assembly of the decorated receptors into homo-and heterodimeric capsules in dichloromethane medium. We obtained homo-dimeric capsule in 64% yield between the tetramethyl phosphonium cation and tetra-spiropyran tetra-urea calixarene. In addition, we obtained exclusive formation of the hetero-dimeric capsules, for both decorated macrocycles in presence of a N-oxide. The dimeric capsules were formed through the establishment of 16 hydrogen-bonding interactions between the urea’s incorporated in the receptors. Disassembly/assembly of these dimeric structures were investigated by means of NMR spectroscopy. Upon acid-induced isomerization of the spiropyran to the protonated merocyanine form we observed the disassembly of the dimeric capsule. Re-assembly of the supramolecular structures were obtained upon neutralization of the medium with base. Under these conditions, the controlled release of the included guest and the reassembly of the all-SP tetra-urea dimers occurred at different extents depending on its calixarene or calixpyrrole scaffold.
We also reported the synthesis of an unprecedent tetra-urea calixarene and calixpyrrole decorated with azobenzene moieties incorporated between the receptor core and the urea groups. We hypothesized that the incorporation of the responsive motifs in this position would lead to higher degree of disassembly of the dimers upon external stimuli. Unexpectedly, no dimeric capsules were obtained with the decorated receptors. This was attributed to the entropic cost needed to assemble in homo- and hetero-dimeric capsules.
Finally, we also presented the synthesis, binding and transport studies of aryl extended calixpyrrole macrocycles decorated with azobenzene motifs. The decorated receptor was obtained through the Mills condensation between the nitroso benzenes and the tetra-amino calixpyrrole. We also reported the formation of thermodynamically and kinetically stable complexes with various tetraalkylammonium chlorinated ion pairs for the equilibrated and light-irradiated samples. Transport efficiency of these responsive receptors was evaluated by means of fluorometric assays (HPTS and Lucigenin) in a model membrane. We demonstrated the effect of the light irradiation in the behaviour of these receptor.
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