SELF-ASSEMBLY THROUGH HYDROGEN-BONDING - PREPARATION AND CHARACTERIZATION OF 3 NEW TYPES OF SUPRAMOLECULAR AGGREGATES BASED ON PARALLEL CYCLIC CA(3)CENTER-DOT-M(3) ROSETTES

Reaction of hub(MM)(3), a compound containing six melamines, with mono meric, dimeric, and trimeric derivatives of isocyanuric acid yields th ree new types of hydrogen-bonded self-assembled supramolecular aggrega tes. These new aggregates are represented by hub(MM)(3):3benz(CA)(2) a nd hub(MM)(3):3furan(CA)(2), hub(MM)(3):6neohex(CA), and hub(MM)(3):3n eohex(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 paralle l cyclic CA(3).M(3) ''rosettes''. Characterization of these aggregates by H-1 and C-13 NMR spectroscopies, gel permeation chromatography, an d 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 d ifferent components into a single supramolecular aggregate. The size a nd stability of these self-assembled aggregates are correlated with re sults obtained from gel permeation chromatography.