Molecular self-assembly through hydrogen bonding: aggregation of five molecules to form a discrete supramolecular structure
摘要:
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).
act as a dual binding site for anions and metal ions. They display a selective downfield shift of the thiourea protons and a remarkable cathodic shift of the ferrocene/ferrocenium redox couple with F−, AcO−, H2PO4−, and HP2O73− anions, whereas the selective recognition of Hg2+ metalcations is achieved either by electrochemical or by spectral measurements. The preferred binding modes are proposed for
Preparation of macrocyclic and ‘C-clamp’ dicarboxylate compounds
作者:Joshua R Farrell、Dylan Stiles、Weiming Bu、Stephen J Lippard
DOI:10.1016/s0040-4020(03)00256-4
日期:2003.3
salt, afforded a novel macrocyclic dicarboxylatecompound in 71% isolated yield. Purification was effected by filtration in a single step. The synthesis and characterization of two new ‘C-clamp’ compounds, which also contain two m-terphenyl carboxylates but exhibit much greater degree of flexibility, are also described. These compounds are of interest as potential ligands or for host–guest chemistry