Organic-Cation Modulated Assembly Behaviors of a Ureidopyrimidone-Grafting Cluster.

Ureidopyrimidone (UPy) is an important building block for constructing functional supramolecular polymers and soft materials based on their characteristic quadruple hydrogen bonds. While the evidence from the single-crystal X-ray diffraction data for the existence of linear hydrogen bonding has still been absent up to now. To obtain the crystals of UPy-containing molecules with high quality, enhanced rigidity and crystallinity are expected.

Hydrogen-Bonded Framework of a Polyanionic Cluster and Its Growth from 2D to 3D for Dual-Selective Adsorption and pH-Controlled Oxidation.

For fabricating a hydrogen-bonded framework with a stabilized hybrid structure for versatile functional properties, an inorganic polyanionic cluster that bears covalently grafted organic groups for hydrogen bond connection is synthesized. By modifying two guanine groups into a disklike polyoxometalate [Mn(OH)MoO] on both sides symmetrically, a polyanionic hybrid building block is obtained. With the cluster serving as a bridge and the grafted guanine unit serving as the binding sites, a polyoxometalate built-in hydrogen-bonded framework in the form of a square lattice shape within a two-dimensional plane has been fabricated as a single-layer assembly.

Near-Infrared Photothermal Catalysis for Enhanced Conversion of Carbon Dioxide under Mild Conditions.

Enhanced conversion of carbon dioxide (CO) for cycloaddition with epoxide derivatives is highly desired in organic synthesis and green chemistry, yet it is still a challenge to obtain satisfactory activity under mild reaction conditions of temperature and pressure. For this purpose, an unexploited strategy is proposed here by incorporating near-infrared (NIR) photothermal properties into multicomponent catalysts. Through the electrostatic adsorption of Co- or Ce-substituted polyoxometalate (POM) clusters on the surface of graphene oxide (GO) with covalently grafted polyethyleneimine (PEI), a series of composite catalysts POMs@GO-PEI are prepared.

Multiple modulations for supramolecular hydrogels of bola-form surfactants bearing rigid and flexible groups.

A series of bola-form surfactants with two identical azobenzene ends separated by a flexible chain but different cationic heads were synthesized. These amphiphilic molecules exhibited rich self-assembly properties in aqueous solutions. The physical characterizations demonstrated that the cationic heads showed a decisive influence on both the gelation behavior and the gel strength.

Cyclodextrin-/photoisomerization-modulated assembly and disassembly of an azobenzene-grafted polyoxometalate cluster.

Herein, a mono-lacunary Keggin-type polyoxometalate (POM), [SiW11O39]8-, grafted with an azobenzene group through Sn ion bridging was prepared, and the formed organic-inorganic hybrid cluster was characterized via elemental analysis, NMR, TGA, and IR techniques. A vesicular structure of the hybrid cluster assembly in aqueous media was observed in the TEM image, and it dissociated in the presence of α-/β-, γ-cyclodextrins (α-/β-, γ-CDs); this dissociation was driven by the host-guest interactions. The monodispersed inclusion complex further reassembled into smaller micelles under irradiation with 365 nm light, and this transformation was reversibly controlled by alternating the irradiation with 450 nm light.

Ratio-Controlled Precursors of Anderson-Evans Polyoxometalates: Synthesis, Structural Transformation, and Magnetic and Catalytic Properties of a Series of Triol Ligand-Decorated {MMo} Clusters (M = Cu, Co, Ni, Zn).

A series of triol ligand [CHC(CHOH)] covalently decorated polyoxometalates (POMs), which could be ascribed to the primary complexes with structural formulas {M[MoO(CHC(CHO))]} (M = Cu, Co, Ni, Zn), have been synthesized in organic solvents. Single-crystal X-ray structural analysis reveals that the synthesized polyanionic clusters are comprised of three {Mo} units and two divalent transition-metal ions connecting to each other in an alternating style, where all {Mo} blocks were covalently decorated by two triol ligands in the trans conformation. The 1/3 molar ratio of M/Mo in the prepared complexes was higher than those ratios in typical Anderson-Evans, Wells-Dawson, and Keggin POMs.

Short Peptides Directing 1D Helical Arrays of Polyoxometalates with Controllable Pitches.

A series of cationic peptides with alternating hydrophilic and hydrophobic residues were elaborately designed and synthesized. These kinds of short peptides with protonated lysine groups can interact with anionic polyoxometalate nanoclusters through multivalent ionic bonds and hydrogen bonds, resulting in the formation of helical polyoxometalate arrays in aqueous solution. Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD), transmission electron microscopy (TEM), and dynamic light scattering (DLS) were utilized to characterize the self-assembled structures.

Facile Synthesis and Optical Properties of Small Selenium Nanocrystals and Nanorods.

Selenium is an important element for human's health, small size is very helpful for Se nanoparticles to be absorbed by human's body. Here, we present a facile approach to fabrication of small selenium nanoparticles (Nano-Se) as well as nanorods by dissolving sodium selenite (NaSeO) in glycerin and using glucose as the reduction agent. The as-prepared selenium nanoparticles have been characterized by X-ray diffraction (XRD), UV-Vis absorption spectroscopy and high resolution transmission electron microscope (HRTEM).

Counterion-dominating chirality transfer between chiral and achiral polyoxometalates.

We show that chirality transfer from chiral polyoxometalates to achiral polyoxometalates can occur in aqueous solution with unexpected selectivity of surrounding counterions. In comparison with sodium ions, protonated dimethylammonium counterions play a critical role in shortening the inter-cluster distance, thus promoting the efficiency of chirality transfer.

Fabrication and optical properties of water soluble CdSeS nanocrystals using glycerin as stabilizing agent.

Herein we present an unusual phosphine-free method to fabricate water soluble CdSeS nanocrystals in cubic structure. In this method, glycerin was used as a stabilizing agent replacing tri-n-octylphosphine oxide (TOPO). Water solution of Na2SeO3 in polyethylene glycol was utilized as Se source.