SELF-ASSEMBLY THROUGH HYDROGEN-BONDING - PREPARATION AND CHARACTERIZATION OF 3 NEW TYPES OF SUPRAMOLECULAR AGGREGATES BASED ON PARALLEL CYCLIC CA3.M3 ROSETTES

Reaction of hub(MM)(3), a compound containing six melamines, with monomeric, dimeric, and trimeric derivatives of isocyanuric acid yields three new types of hydrogen-bonded self-assembled supramolecular aggregates. These new aggregates are represented by hub(MM)(3):3benz(CA)(2) and hub(MM)(3):3furan(CA)(2), hub(MM)(3):6neohex(CA), and hub(MM)(3):3neohex(CA):C(18)hub(CA)(3). These supramolecular aggregates comprise 4-7 individual molecules and have molecular weights in the range 4.1-6.3 kDa. Each aggregate is stabilized by 36 hydrogen bonds in two parallel cyclic CA(3).M(3) ''rosettes''. Characterization of these aggregates by H-1 and C-13 NMR spectroscopies, gel permeation chromatography, and vapor pressure osmometry confirms that each exists as a stable, well-defined structure in chloroform or methylene chloride solutions. The design of these self-assembled aggregates, their relative stabilities,and the techniques used for their characterization are discussed. The operation of positive cooperativity in the self-assembly of hub(MM)(3):6neohex(CA) is demonstrated. The self-assembly of hub(MM)(3):3neohex(CA):C(18)hub(CA)(3) demonstrates the controlled aggregation of three different components into a single supramolecular aggregate. The size and stability of these self-assembled aggregates are correlated with results obtained from gel permeation chromatography.