ORGN 693 |
| We have recently developed a set of selective amine sulfonylation reactions which allow assembling oligosulfonimide dendrimers. The unique opportunity to tailor the branched architecture in a systematic manner prompted us to look into the little explored phenomena of (i) isomerism and (ii) self-assembly of dendrimers. (i) Isomeric dendrimers reported so far contain constitutional differences at their branching points. The isomers of this type can be represented by the same planar topological graph. Our objective was to make isomeric dendrimers that could be represented by different graphs. Shuffling branching points and terminal units in dendritic structures should impact a range of physical properties. To investigate the influence of the branched topology on the properties series of isomeric dendrimers (dendroisomers) with four to ten terminal groups were synthesized and investigated with regard to their melting, solubility, spectroscopic and hydrodynamic characteristics. (ii) Dendritic molecules capable of self-assembling have potential applications as liquid crystalline and electronic materials. Oligosulfonimide dendrimers proved useful in supramolecular design, particularly in crystal engineering. Although, only low-molar-mass branched structures form X-ray quality crystals, the information about their stereochemical features and modes of intermolecular interactions in the solid state can be transferred onto larger oligosulfonimide dendrimers. Analysis of six different X-ray structures of dendritic sulfonimides reveal that the crystallization is driven by π-donor/π-acceptor stacking, CH•••O hydrogen bridges, and CH-π non-covalent interactions. Compounds bearing 2-naphthylsulfonimide wedges show reproducible packing motif that can be employed in crystal engineering. The intermolecular π-donor/π-acceptor interactions were also proven to exist in chloroform solutions. The strength of the non-covalent contacts was rationalized by quantum chemical calculations. |
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Asymmetric Reactions, Combinatorial Chemistry, Molecular Recognition and Self-Assembly, Proteins, Peptides, Amino Acids and Enzyme Inhibitors
8:00 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |