The host–guest complex formation between barbital and various acylaminopyridyl isophthalamides (Hamilton receptors) has been determined quantitatively. The syntheses of nine isophthalamides are described. Their structures differ in the substitution patterns on the central isophthalic unit, and the natures of the acyl residues. Ethylhexanoyl derivatives proved to be more soluble than pentanoyl amides. The association constants were determined by 1H NMR titrations monitoring chemically induced shifts (CIS values), by 1H NMR diffusion experiments, and by isothermal titration calorimetry (ITC), giving Kass values in chloroform at 298 K between 33 × 103 and 100 × 103 M–1.

A second-generation supramolecular dendrimer has been prepared by orthogonal multiple hydrogen bonding. In the first (inner) recognition domain, the interaction of one bis-isocyanuric acid (25) with two branching units (21) that carry complementary Hamilton receptors has been exploited. In the second (outer) generation, the two ADDA (A=hydrogen-bond acceptor, D=donor) receptors of each branching unit (21) have bound complementary DAAD units (4). The problem of limited solubility of the building blocks has been overcome by the introduction of branched ethylhexyl residues and by the use of flexible alkylene or oligo(ethylene glycol) linking chains. The orthogonal binding of the two hydrogen-bonding pairs was elucidated by chemical induced shift NMR titrations, which proved that the two pairs, isocyanuric acid with the Hamilton receptor and ADDA with DAAD, bind preferentially. The formation of the supramolecular self-assembled 1:2:4 dendrimer with a molecular weight of 5065 g mol(-1) was investigated by diffusion NMR spectroscopy.

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Two demonstrations are presented that show the immiscibility of five or six layers of liquids. The setup of both demonstrations is such that one homogeneous layer in a multiphasic mixture separates into two new layers upon shaking. The solvents used are methanol, toluene, petroleum ether or n-pentane, silicone oil, perfluoroheptanes, and water for the five-layer demonstration. Addition of mercury results in a sixth phase.

SummaryA bi-macrocycle with an incorporated isophthalamide substructure was synthesized by double amide formation between an isophthaloyl dichloride and two equivalents of a bis(alkenyloxy)aniline, followed by ring-closing metathesis and hydrogenation. In contrast to many related isophthalamides, the concave host exhibits a better binding for oxides, such as DMSO or pyridine-N-oxide, than for halide anions. A general method for a quick estimation of the strength of binding derived from only a few data points is presented and gives an estimated K ass of pyridine-N-oxide of ca. 40 M−1, NMR titration confirms 25 M−1.