Guanglu Wu

Tsinghua University, Beijing, Beijing Shi, China

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Publications (12)66.39 Total impact

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    ABSTRACT: The role of hydrotropic counteranions in governing the self-assembled structures of cationic bolaamphiphiles is studied in this work. We reveal that the ability of a hydrotropic counteranion to induce the formation of two-dimensional (2D) planar aggregates depends weakly on its polar head, but is strongly correlated to the size and the substituted pattern of its organic portion. Additionally, the shape of the obtained 2D planar aggregates can be modulated, interestingly, both by hydrotropic counteranions and the embedded conjugated moieties. 2D planar aggregates with a shape of triangle, quadrangle, and hexagon are obtained, which may provide a simple and feasible methodology for fabricating organic self-assembled structures with controlled features.
    Chemical Science 04/2014; · 8.31 Impact Factor
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    ABSTRACT: A series of bolaform supra-amphilphiles with different symmetries were fabricated through dynamic benzoic imine bond formation. The pH dependence of imine formations of these supra-amphiphiles were characterazied. We found that the extents of the imine formation of these supra-amphiphies were different. The supra-amphiphiles with a poorer symmetry always exhibited a lower imine formation at a given pH. Therefore, the varied extents of imine bond formation indicate the different aggregations of these supra-amphilphiles, which are controlled by the molecular symmetry of the supra-amphiphiles.
    Langmuir 01/2014; · 4.38 Impact Factor
  • Jun Xu, Guanglu Wu, Zhiqiang Wang, Xi Zhang
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    ABSTRACT: This research is aimed to understand the growth mechanisms for self-assembly of dialkylated melamine derivatives. The dialkylated melamine derivatives with different alkyl chains (Mela-m-n) are able to self-assemble with hydrochloric acid in dichloromethane to form 2D organic assemblies, exhibiting similar lamellar structures as Mela-n•HCl with identical alkyl chains. The most interesting finding is that the growth mechanism of Mela-n•HCl with identical alkyl chains is revealed to be a layer growth, while Mela-m-n•HCl with asymmetric alkyl chains adopts a spiral growth mechanism. The asymmetric alkyl chains in Mela-m-n may lead to the formation of dislocation, which is responsible for the spiral growth mechanism.
    Langmuir 08/2013; · 4.38 Impact Factor
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    ABSTRACT: We have fabricated supra-amphiphiles by charge-transfer complexation of azulene-based amphiphiles and pyrene in water, and the self-assembled nanostructures can reversibly change between cylindrical micelles and disklike nanosheets in response to interaction with guest molecules.
    Chemical Communications 01/2013; · 6.38 Impact Factor
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    ABSTRACT: Self-assembly of cationic bolaamphiphiles is usually reported to form one-dimensional (1D) or zero-dimensional (0D), rather than two-dimensional (2D) structures. Here we have found a facile counterion-directed structure switch for such amphiphilic moieties. 0D/1D structures formed by self-assembly of cationic bolaamphiphiles can be converted into 2D planar structures by a simple counterion change to tosylate. As indicated by the single crystal structure and variable-temperature NMR studies, the strong binding between tosylate counterions and cationic headgroups drives the formation of 2D planar structures. It is highly anticipated that this approach may present as a simple methodology to control the stacking of the embedded conjugated cores in bolaamphiphiles, therefore modulating optoelectronic properties and function in such assemblies.
    Chemical Science 01/2013; 4(12):4486-4493. · 8.31 Impact Factor
  • Jun Xu, Guanglu Wu, Zhiqiang Wang, Xi Zhang
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    ABSTRACT: Dialkylated melamine derivatives self-assemble with halogen acids into 2D organic microsheets in organic solvent through counterion bridged multiple hydrogen bonds as well as electrostatic interactions and π–π stacking. Alkyl chains are introduced to suppress the growth in a particular dimension, supplying a general approach for the fabrication of 2D structures. Protonation is demonstrated to be a crucial factor in the formation of 2D assemblies. The assembly and disassembly of microsheets can be reversibly controlled by alternating addition of acid and base. Even the aspect ratio of the rectangular microsheets can be further modulated through the addition of different amounts of acid.
    Chemical Science 10/2012; 3(11):3227-3230. · 8.31 Impact Factor
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    ABSTRACT: A bolaamphiphile (5,5-B2NBr8) bearing a functional bipyridine moiety as the mesogenic core is reported for the first time. 5,5-B2NBr8 was found to self-assemble into uniform fibrous structure in aqueous solution, when the concentration was higher than cmc. Analogues of 5,5-B2NBr8 with structural differences in chain length, headgroup, mesogenic core, and substituted position were synthesized, elucidating that small variances of the molecular structure could lead to dramatic changes of the resulting assemblies. For example, compound 4,4-B2NBr8 showed only spherical colloidal aggregates rather than fibers as 5,5-B2NBr8 did, while the only difference between them was the position at which the alkyl chains were attached onto bipyridine. A probable model for the fibrous structure of 5,5-B2NBr8 was proposed. Moreover, exploiting the coordination capacity of bipyridine, assembly and disassembly of 5,5-B2NBr8 could be reversibly controlled through the addition of EDTA and Cu(II), respectively.
    Langmuir 03/2012; 28(11):5023-30. · 4.38 Impact Factor
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    ABSTRACT: Stable multilayer films were fabricated on the basis of the alternating layer-by-layer assembly of a two-component bolaform supramolecular amphiphile and diazoresins, followed by photochemical cross-linking of the structure. UV-visible spectroscopy and atomic force microscopy revealed a uniform deposition process. Moreover, one component of the supramolecular amphiphile can be removed from the multilayer films after cross-linking between the second component and the diazoresin. The release and uptake of the imprinted supramolecular amphiphile component are shown to be reversible. Furthermore, uptake experiments of different molecules show the selectivity of the imprinted sites for the template molecule. Thus, surface-imprinted films can be formed by employing dissociable two-component supramolecular amphiphiles. This research reveals that supramolecular amphiphiles can be used as a novel concept for the construction of multilayer films, and it also provides a new method of generating surface-imprinted multilayers.
    Langmuir 08/2011; 27(17):10370-5. · 4.38 Impact Factor
  • Ying Yu, Guanglu Wu, Kai Liu, Xi Zhang
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    ABSTRACT: The force required to disassemble block copolymer micelles in water has been directly investigated via atomic force microscopy-based single-molecule force spectroscopy. The force needed to disassemble block copolymer micelles of poly(acrylic acid)-polyfluorene-poly(acrylic acid) in water is found to be 23 pN. The force increases as the stretching velocity increases, indicating that micelle disassembly is a dynamic process. In addition, the disassembly force is sensitive to the properties of the solvents. This study represents the first attempt to employ single-molecule force spectroscopy to directly measure the force needed to disassemble block copolymer micelles in water.
    Langmuir 06/2010; 26(12):9183-6. · 4.38 Impact Factor
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    ABSTRACT: A multilayer film consisting of poly(acrylic acid) (PAA) and an azobenzene-containing surfactant (AzoTEA) was fabricated via a layer-by-layer assembly technique. The micellar structure favored by AzoTEA while in solution results in a bilayer structure when deposited on a substrate surface. This aggregation conversion behavior favors the deposition of AzoTEA and PAA in an alternating pattern to form a photoresponsive multilayer film. The molecular amphiphilicity of AzoTEA can be tuned by photoisomerization of the azobenzene moiety, which affects the aggregation behavior of AzoTEA in both films and solutions. The disassembly of AzoTEA aggregates caused by photoirradiation can induce the disassembly of the whole multilayer film. The AzoTEA-PAA multilayer films were found to be stable in pH 4 acetic acid (AcOH) solution, unless treated with UV radiation. On the basis of the different stability of multilayers with or without photoirradiation, when the multilayer films are selectively irradiated with UV light, the regions exposed to UV radiation disassembled after being immersed in pH 4 AcOH solution for 10 min but the regions not exposed to photoradiation are maintained on the substrate. Moreover, the plausible mechanism for the assembly and disassembly of these multilayer films and the confirmation of erasable films by atomic force microscopy are discussed.
    Langmuir 03/2010; 26(12):9736-41. · 4.38 Impact Factor
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    ABSTRACT: A new type of bolaamphiphile bearing bipyrimidine (bpym-8) has been designed and synthesized. The bipyrimidine moiety allows for metal-ligand coordination, thereby influencing the self-assembly of the bolaamphiphile. Before coordination, bpym-8 self-assembles in water to form spherical aggregates. An interesting finding is that the coordination of the Cu(II) ion with bipyrimidine can induce the assembly of bpym-8 to change from spheres to clustered aggregates. It should be noted that the assembly of bpym-8 can be reversibly converted back by removing the Cu(II) ion from the coordination. This study presents a new type of bolaamphiphile that is able to coordinate with metal ions, which may provide a new clue in fabricating reversibly tunable supramolecular nanomaterials.
    Langmuir 11/2009; 25(23):13306-10. · 4.38 Impact Factor
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    ABSTRACT: In this article, we have demonstrated a universal method for improving the stability of polyelectrolyte multilayer films by designing a photoreactive polyanion as the building block for layer-by-layer (LbL) self-assembly. By grafting an azido group into poly(acrylic acid), we synthesized a photoreactive polyanion, which can induce the photo-crosslinking between the azido group and polymeric backbone under UV irradiation. Our results show that after photocross-linking, the stability of the polyelectrolyte multilayer is greatly improved. Considering that the polyanion-bearing azido group is highly reactive, we have shown that it can be used to stabilize different LbL films. Moreover, by taking advantage of the different stability before and after UV irradiation, a patterned surface can be fabricated, which could be used as a template for selective adsorption.
    Langmuir 04/2009; 25(5):2949-55. · 4.38 Impact Factor

Publication Stats

21 Citations
66.39 Total Impact Points

Institutions

  • 2009–2013
    • Tsinghua University
      • • Key Laboratory of Organic Optoelectronics and Molecular Engineering
      • • Department of Chemistry
      Beijing, Beijing Shi, China