Reinforcement of a Sugar-Based Bolaamphiphile/Functionalized Graphene Oxide Composite Gel: Rheological and Electrochemical Properties

A sugar-based bolaamphiphile/graphene oxide composite hydrogel has been prepared using simple mixing. Unlike the corresponding sugar-based native gel, the composite gel exhibits a fibrillar structure with a 10–20 nm fiber diameter. The composite gel forms an interdigitated bilayer structure incorporating intermolecular hydrogen-bonding interactions. The composite gel formation did not change the beneficial electrical properties of graphene offering the potential for integration of this new material into electronic systems. Interestingly, the mechanical and electrochemical properties of the composite gel are both dramatically enhanced when compared to the native gel, thereby reflecting that the functionalized graphene oxide layers are efficiently intercalated within the composite gel structure

Bis(naphthol)-based fluorescent chemoprobe for cesium cation and its immobilisation on silica nanoparticle as a high selective adsorbent

<p>A bis(naphthol)-based cation receptor <b>1</b> has been synthesised by three steps of synthetic procedure. The spectroscopic properties of <b>1</b> upon addition of various metal ions were investigated by UV–vis absorption and fluorescence spectroscopy. As a result, the absorption of <b>1</b> was linearly decreased as a function of concentration of added Cs⁺. Also, <b>1</b> exhibited dramatic fluorescence quenching effect upon exposure to caesium cation. Contrastively, no significant quenching effect was observed upon addition of other metal ions such as Na⁺, K⁺, Rb⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ni²⁺ and Zn²⁺. It was found that <b>1</b> formed a 1:1 complex with Cs⁺ by Job’s plot. Furthermore, we also prepared <b>1</b>-functionalised silica nanoparticle (<b>SiO</b>_<b>2</b><b>-1</b>) as an adsorbent for Cs⁺. <b>SiO</b>_<b>2</b><b>-1</b> showed a great capacity for selective removal of caesium ion from aqueous solution as well as from tap water. Thus, it is potentially useful for the detection and removal of caesium cation from environmental and biological fluids polluted by nuclear radiation and nuclear waste.</p

Chiral Supramolecular Gels with Lanthanide Ions: Correlation between Luminescence and Helical Pitch

We report the correlation between the fluorescence intensity and the helical pitch of supramolecular hydrogels with Tb­(III) and Eu­(III) as well as their inkjet printing patterning as an application. The luminescent gels, which exhibited three different emissions of red, green, and blue, could be prepared without and with Eu­(III) and Tb­(III). The luminescence intensity of supramolecular gels (gel-Tb and gel-Eu) composed of Tb­(III) and Eu­(III) was ca. 3-fold larger than that of the sol (<b>1</b>+Tb­(III) or <b>1</b>+Eu­(III)), which was attributed to large tilting angles between molecules. By AFM observations, these gels showed well-defined right-handed helical nanofibers formed by coordination bonds in which the helical pitch lengths were strongly dependent on the concentrations of lanthanide ions. In particular, the large luminescence intensity of gel-Tb exhibited a smaller helical pitch length than that of gel-<b>1</b> due to relatively weak π–π stacking with large tilting angles between molecules. The luminescence intensities were enhanced linearly with increasing concentrations of lanthanide ions. This is the first example of the correlation between the helical pitch length and the luminescence intensity of supramolecular materials. The coordination bonding in supramolecular hydrogels had a strong influence on rheological properties. We also developed a water-compatible inkjet printing system to generate luminescent supramolecular gels on A4-sized paper. The images of a logo and the text were composed of three different emissions and were well-printed on A4 sized paper coated with gel-<b>1</b>

Transfer and Dynamic Inversion of Coassembled Supramolecular Chirality through 2D-Sheet to Rolled-Up Tubular Structure

Transfer and inversion of supramolecular chirality from chiral calix[4]­arene analogs (<b>3D</b> and <b>3L</b>) with an alanine moiety to an achiral bipyridine derivative (<b>1</b>) with glycine moieties in a coassembled hydrogel are demonstrated. Molecular chirality of <b>3D</b> and <b>3L</b> could transfer supramolecular chirality to an achiral bipyridine derivative <b>1</b>. Moreover, addition of 0.6 equiv of <b>3D</b> or <b>3L</b> to <b>1</b> induced supramolecular chirality inversion of <b>1</b>. More interestingly, the 2D-sheet structure of the coassembled hydrogels formed with 0.2 equiv of <b>3D</b> or <b>3L</b> changed to a rolled-up tubular structure in the presence of 0.6 equiv of <b>3D</b> or <b>3L</b>. The chirality inversion and morphology change are mainly mediated by intermolecular hydrogen-bonding interactions between the achiral and chiral molecules, which might be induced by reorientations of the assembled molecules, confirmed by density functional theory calculations