MOLECULAR SELF-ASSEMBLY THROUGH HYDROGEN-BONDING - AGGREGATION OF 5 MOLECULES TO FORM A DISCRETE SUPRAMOLECULAR STRUCTURE

This article describes reactions of the trivalent melamine derivatives C6H3-1,3,5-[CONHC6H4-3-N(CH2C6H4-4-C(CH3)3) COC6H3-2-(NHC3N3(NH2)(NHCH2CH2C(CH3)3))-5-Br]3 (hubM3) and (CH3)3COC(O)NHC[CH2O(CH2) 3-SCH2C(O)NHC6H4-2-NHC3N3(NH2)(NH(CH2)2C(CH3)3)]3 (trisM3) with the bivalent isocyanurate derivatives C6H2-1,5-[CH(CH3)2]2-2,4-[CH2NC(O)NHC(O)NHC(O)]2 (benzCA2) and C4O-2,5-[CH(CH3)2]2-3,4-[CH2NC(O)NHC(O)-NHC(O)]2 (furanCA2) in CHCl3 to afford a series of supramolecular aggregates containing 2 equiv of the tris melamine and 3 equiv of the bis cyanurate (2 + 3 complexes). These complexes consist of two parallel hydrogen-bonded lattices that incorporate 36 hydrogen bonds. The structures have been characterized by H-1 NMR, C-13 NMR, and UV spectroscopies, gel permeation chromatography, and vapor pressure osmometry. These techniques demonstrate that the 2 + 3 aggregates in CHCl3 solution are stable and structurally well-defined. hubM3 is more rigid than trisM3. This difference in rigidity is used to probe the relationship between the molecular structure of the trivalent melamine derivative and the geometry and stability of the resulting aggregate. (hubM3)2(benzCA2)3 and (hubM3)2(furanCA2)3 each seem to exist in one isomeric form; (trisM3)2(benzCA2)3 and (trisM3)2(furanCA2)3 are both mixtures of isomers (due, probably, to the relative flexibility of the arms of trisM3).