Revisiting the formation and tunable dissociation of a [2]pseudorotaxane formed by slippage approach.

A new [2]pseudorotaxane DB24C8⊃1-H · PF6 with dibenzo[24]crown-8 (DB24C8) crown ether-dibenzylammonium (1-H · PF6) binding which was formed by slippage approach at different solvents and temperature, had been isolated and characterized by NMR spectroscopy and mass spectrometry. The [2]pseudorotaxane DB24C8⊃1-H · PF6 was stable at room temperature. The dissociation rate of [2]pseudorotaxane DB24C8⊃1-H · PF6 could be tuned by using different stimuli such as triethylamine (TEA)/diisopropylethylamine (DIPEA) and dimethyl sulfoxide (DMSO).

Click-dendronized poly(amide-triazole)s--effect of dendron size and polymer backbone symmetry on self-assembling and gelation properties.

Nine dendronized poly(amide-triazole)s 2-Gm Gn (m=1-3, n=1-3), were prepared by the 1:1 copolymerization between AA-type dendritic diazides 4-Gm (m=1-3) and BB-type dendritic diacetylenes 5-Gn (n=1-3) under the copper(I)-mediated click coupling conditions. The degree of polymerization value of the polymers was found to range from 15-50, and decreased with increasing size of the dendron, suggesting steric hindrance had a retardation role on the copolymerization efficiency. Based on FT-IR and (1)H NMR studies, it was found that significantly strong, interchain hydrogen bonding between the amide units was present in the solution state after copolymerization, whereas the monomers 4-Gm and 5-Gn were devoid of any intermolecular hydrogen-bonding interaction.

The effects of microenvironment polarity and dendritic branching of aliphatic hydrocarbon dendrons on the self-assembly of 2-ureido-4-pyrimidinones.

Two series of aliphatic hydrocarbon-based G1-G3 dendritic 2-ureido-4-pyrimidinones (UPy) (S-Gn)₂ and (L-Gn)₂, differing from one another by the distance between the branching juncture to the urea end, were prepared and characterized. These hydrocarbon dendrons were also appended to a p-aminonitrobenzene solvatochromic chromophore in order to probe their microenvironment polarity. While positive solvatochromism was observed which indicated the chromophore was solvent accessible, there was no significant difference between the microenvironment polarities on going from the G1 to the G3 dendrons.

Conformational and supramolecular properties of main chain and cyclic click oligotriazoles and polytriazoles.

This Feature Article gives a summary on the conformational and supramolecular properties of a special type of click molecules, namely, main chain and cyclic oligo- and polytriazoles. The triazole ring is an interesting structural motif since it is a hydrogen bond donor and acceptor, a large molecular dipole and also a metal ligand. It can interact with a wide variety of functionalities, e.