No abstract

Anthracenebisresorcinol derivative 1 as an organic network material shows a novel catalysis in the solid state for the acrolein-cyclohexadiene Diels-Alder reaction. The suggested mechanism involves a catalytic cycle composed of sorption of the reactants in the cavities of polycrystalline host 1, preorganized intracavity reaction, and desorption of the product. The host also promotes stereoselective intracavity reactions for alkyl acrylates and cyclohexadiene but, in this case, not in a catalytic manner. Relevance of the present system as a functional organic analog of zeolites is discussed in light of the kinetics of respective elementary processes and the effects of pulverization of the catalyst thereupon as well as X-ray crystal structures.

Macrocyclic glycocluster compounds 2n (n = 2-7) with four alkyl (undecyl) chains and eight oligosaccharide moieties on the opposite sides of the calix[4]resorcarene macrocycle are prepared from the reactions of the corresponding octaamine derivative with maltooligosaccharide lactones. Combined evidence from dynamic light scattering (DLS), gel permeation chromatography (GPC), and transmission electron microscopy (TEM) indicates that they form small micelle-like nanoparticles (d congruent with 3 nm) in water. In the presence of Na2HPO4/NaH2PO4, nanoparticles are agglutinated with phosphate ions as a glue to grow in size up to 60-100 nm, as revealed by DLS as well as microscopy (TEM and AFM). The phosphate-induced agglutination processes can be followed by surface plasmon resonance (SPR). Amphiphile 2n is readily immobilized on the hydrophobized sensor chip of SPR to give a closely packed monolayer with oligosaccharide moieties exposed to bulk water. While there is no further adsorption of 2n on the resulting monolayer, this does occur when the latter is pretreated with the phosphate salts, ultimately giving rise to a multilayer upon repeated treatment of the chip with 2n and Na2HPO4/NaH2PO4 in an alternate manner. Kinetic analyses show that the phosphate-mediated inter(saccharide) interactions in terms of rate and affinity are markedly dependent on the oligosaccharide chain lengths (n), becoming more favorable with increasing n's. The novel aggregation and agglutination behaviors observed are discussed in terms of immobilizable and irreversible micelles on the basis of the cone-shaped structure of quadruple-chain amphiphile 2n having a huge saccharide pool and the efficiency of multiple hydrogen bonding therein. The unique intermolecular binding properties of compound 22 and analogues so far reported are reviewed in light of the present finding.