| Abstract [eng] |
The aim of this thesis is to explore stereochemical multiplicity of the bicyclo[3.3.1]nonane framework for the construction of chiral, C2-symmetric supramolecular preprogrammed synthons containing hydrogen bonding recognition patterns at both ends of the molecule. The resulting cleft molecules would be utilized for the formation of tubular structures via end-to-end association of these synthons. General synthetic strategies leading to three generations of novel chiral cleft molecules were developed by fusing bicyclo[3.3.1]nonane framework with heteroaromatic rings containing two, three and four hydrogen bonding complementary modules. The first generation cavity compound, containing 2-pyridone hydrogen bonding unit forms tubular assemblies of moderate size (up to 10 molecules in CD2Cl2) in solution. The second generation compound, containing isocytosine unit, forms very stable hydrogen bonded tetramers via self-complementariness of its two tautomeric forms. The new term, tautoleptic aggregation, is introduced for describing this type of aggregation. The supramolecular tetramer undergoes reversible stacking in non-polar solvents resulting in tubular structure. The preference for the formation of tetramer or stacked polymer depends on the bulkiness of substituent on the bicyclic moiety. Preliminary results show that the cavity of the tetramer is well suited to encapsulate C60 molecules. The aggregation of third generation compound, containing quadruple 2-ureido pyrimidinone module is limited to the formation of dimers and trimers only. The small degree of association is attributed to steric crowding in the assembly implied by bulky solubilizing groups. |
