Reaction of Amino-Terminated PAMAM Dendrimers with Carbon Dioxide in Aqueous and Methanol Solutions.

Polyamines have been used as active materials to capture carbon dioxide gas based on its well-known reaction with amines to form carbamates. This work investigates the reactions between three amino-terminated poly(amidoamine) (PAMAM) dendrimers (G1, G3 and G5) and CO(g) in aqueous (DO) and methanolic (CDOD) solutions. The reactions were monitored using H NMR spectroscopy, and yielded dendrimers with a combination of terminal carbamate and terminal ammonium groups.

Cucurbiturils as Effectors on the Self-Assembly of Pd(II) and Pt(II) Metallacycles.

Four bidentate, dicationic ligands () were prepared and investigated as guests for binding by the cucurbit[7]uril (CB[7]) host and structural components for metal (Pd and Pt)-coordinated self-assembly into metallacycles. In aqueous solutions, all the ligands were found to form stable complexes of variable stoichiometries with CB[7], and only one () failed to self-assemble, induced by the presence of suitable Pd or Pt complexes, into metallacycles. Exposure of the Pd-based metallacycles to CB[7] led to their disassembly at room temperature, while the Pt-based metallacycles remained stable under these conditions.

Visualization and quantitation of electronic communication pathways in a series of redox-active pillar[6]arene-based macrocycles.

While oxidized pillar[5]arenes with 1-5 benzoquinone units are known, very few examples of oxidized pillar[6]arenes have been reported. We describe here the synthesis, characterization and electrochemical behavior of a series of macrocyclic hosts prepared by the stepwise oxidation of 1,4-diethoxypillar[6]arene, resulting in high-yield and high-purity isolation of two constitutional isomers for each macrocycle, in which two, three or four 1,4-diethoxybenzene units are replaced by benzoquinone residues. A careful structural comparison with their counterparts in the pillar[5]arene framework indicates that the geometries of the macrocycles are better described as non-Euclidean hyperbolic hexagons and elliptic pentagons, respectively.

Kinetics and Thermodynamics of Binding between Zwitterionic Viologen Guests and the Cucurbit[7]uril Host.

The host-guest binding interactions between a series of zwitterionic, symmetric viologens, and the cucurbit[7]uril host were investigated using NMR and UV-vis spectroscopic techniques. The nature of the viologen side arms had strong effects on the kinetics of association and dissociation and weaker, more uniform influence on the thermodynamic stability of the final 1:1 inclusion complexes, which can also be characterized as pseudorotaxanes.

Bioluminescent Protein-Inhibitor Pair in the Design of a Molecular Aptamer Beacon Biosensing System.

Although bioluminescent molecular beacons designed around resonance quenchers have shown higher signal-to-noise ratios and increased sensitivity compared with fluorescent beacon systems, bioluminescence quenching is still comparatively inefficient. A more elegant solution to inefficient quenching can be realized by designing a competitive inhibitor that is structurally very similar to the native substrate, resulting in essentially complete substrate exclusion. In this work, we designed a conjugated anti-interferon-γ (IFN-γ) molecular aptamer beacon (MAB) attached to a bioluminescent protein, luciferase (GLuc), and an inhibitor molecule with a similar structure to the native substrate coelenterazine.