Weifeng Bu

Star-like supramolecular polymers fabricated by a Keplerate cluster with cationic terminated polymers and their self-assembly into vesicles

The electrostatic combination of a Keplerate cluster, [Mo(132)O(372)(CH(3)COO)(30)(H(2)O)(72)](42-) with cationic terminated poly(styrene) yields polyoxometalate-based supramolecular star polymers, which can further self-assemble into vesicular aggregates in CHCl(3)-MeOH mixed solvent.

Polyoxometalate-modulated self-assembly of polystyrene-block-poly(4-vinylpyridine)

Polyoxometalates can serve as active components to induce and modulate the micellization behavior of polystyrene-block-poly(4-vinylpyridine).

Synthesis and characterization of a luminescence metallosupramolecular hyperbranched polymer

A luminescence supramolecular hyperbranched polymer is reversibly fabricated by successively adding acid and base to a solution of an AB2 platinum(II) monomer in dichloromethane on the basis of acid-base controllable host-guest recognition of dibenzo[24]crown-8 moieties with dialkylammonium ion centers.

Spherical polymer brushes in solvents of variable quality: an experimental insight by TEM imaging.

The spherical micelle and vesicle composed of [PW12O40](3-) and poly(styrene-b-4-vinylpyridinium methyl iodide) are regarded as a model system to study spherical polymer brushes (SPBs) in solvents of various quality. The pure repulsions occur for the brush chains in the chloroform solution and chloroform/methanol mixture with a methanol volume ratio of 9.1%, where the grafted polystyrene chains have a relatively extended conformation. Further increase in the methanol concentrations leads to the presence of the intra/inter-brush van der Waals attractions. Transmission electron microscopy studies show that there is a coexistence of isolated and oligomeric SPBs and multi-SPB aggregates (MSAs) with the methanol content from 17% to 23%. Only MSAs are detected with the increasing methanol content. Both the corona and core shrink significantly in the isolated and oligomeric SPBs and MSAs. The full interpenetration of the grafted chains is observed between the cores in the oligomeric SPBs and MSAs.

Luminescent polymeric hybrids formed by platinum(II) complexes and block copolymers

The incorporation of platinum(II) complexes into block copolymers leads to the formation of luminescent polymeric hybrids with hierarchical nanostructures from spherical, rodlike micelles to vesicles in solvents.

A surfactant-encapsulated polyoxometalate complex towards a thermotropic liquid crystal

A novel surfactant-encapsulated terbium-substituted heteropolyoxotungstate complex [L1]13[Tb(SiW11O39)2].30H2O (SEC-1) bearing mesomorphous groups was successfully prepared by the ionic self-assembling route, exhibiting characteristic thermotropic liquid-crystalline behavior.

Reversible luminescence switching accompanied by assembly-disassembly of metallosupramolecular amphiphiles based on a platinum(II) complex

The electrostatic self-assembly of anionic surfactants with a cationic platinum(II) complex bearing triethylene glycol leads to the formation of metallosupramolecular amphiphiles with rod- and sheet-like aggregates in aqueous solutions. The resulting solutions show strong luminescence enhancement, which can decrease back to the original emissive intensity of the platinum(II) complex by disassembling the aggregates through host–guest recognition with α-cyclodextrin. Both the self-assembly and disassembly processes are monitored in real time by UV-vis absorption and emission spectra and dynamic light scattering. The critical aggregation concentrations are determined by concentration-dependent measurements of emission spectra and dynamic light scattering. The present study provides an efficient and convenient strategy to fabricate dynamic metallosupramolecular amphiphiles with controllable photophysical properties.

Organic–inorganic hybrids formed by polyoxometalate-based surfactants with cationic polyelectrolytes and block copolymers

Electrostatic self-assembly of an Anderson-based surfactant with polyelectrolytes and block copolymers leads to the formation of polyoxometalate-based polyelectrolyte–surfactant and block ionomer complexes, respectively. Furthermore, vesicular aggregates form in the solutions of the block ionomer complexes.

Self-assembly of star micelle into vesicle in solvents of variable quality: the star micelle retains its core-shell nanostructure in the vesicle.

Intra- and intermolecular interactions of star polymers in dilute solutions are of fundamental importance for both theoretical interest and hierarchical self-assembly into functional nanostructures. Here, star micelles with a polystyrene corona and a small ionic core bearing platinum(II) complexes have been regarded as a model of star polymers to mimic their intra- and interstar interactions and self-assembled behaviors in solvents of weakening quality. In the chloroform/methanol mixture solvents, the star micelles can self-assemble to form vesicles, in which the star micelles shrink significantly and are homogeneously distributed on the vesicle surface. Unlike the morphological evolution of conventional amphiphiles from micellar to vesicular, during which the amphiphilic molecules are commonly reorganized, the star micelles still retain their core-shell nanostructures in the vesicles and the coronal chains of the star micelle between the ionic cores are fully interpenetrated.

Self-assembled monolayers of CH3COS- terminated surfactant-encapsulated polyoxometalate complexes.

Self-assembled monolayers (SAMs) on gold surfaces based on three kinds of acetylthio-surfactant-encapsulated polyoxometalate clusters (thio-SECs) terminated with multiple CH(3)COS- groups, (NC(26)H(55)S(CO)CH(3))(6)H(2)[Co(H(2)O)CoW(11)O(39)], (NC(26)H(55)S(CO)CH(3))(13)H(3)[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)], and (NC(26)H(55)S(CO)CH(3))(13)[Fe(4)(H(2)O)(2)(P(2)W(15)O(56))(2)]Br, have been prepared, which is representative of a general methodology to fabricate polyoxometalate-based SAMs. Thio-SECs self-assembled into monolayers on gold surfaces through the hydrolysis of CH(3)COS- groups and the subsequent formation of S-Au bonds, which was confirmed by grazing angle infrared spectroscopy, X-ray photoelectron spectroscopy, and ellipsometric and scanning tunneling microscopy (STM) measurements. Furthermore, the SAMs of the thio-SECs possess closely packed structures, and the local short-range order is clearly observed in the magnified STM image. We have also investigated the electrochemical behavior of SAMs of thio-SECs by cyclic voltammetry in detail, and the redox potential of the original polyoxometalates has been well retained. The electrochemical signals of the SAMs are very weak because of the small moiety of thio-SECs that are electrochemically accessible in the cyclic voltammetry experiments. The polyoxometalate-modified electrodes that we prepared are not only highly ordered in the local short range but also stable in electrochemical cycling because of the multiple S-Au bonds of thio-SECs on the gold substrates that aid in the construction of functional materials such as electrochemical and electrocatalytic devices.