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Haolong Li

Publications and source records attributed to Haolong Li.

6 recordsLinked to original sources
PubMed2006

Self-organized microporous structures based on surfactant-encapsulated polyoxometalate complexes.

Self-organized microporous structures based on a series of surfactant-encapsulated polyoxometalate complexes (SECs) have been prepared by using ordered condensed droplets as a template. Among these structures, ordered honeycomb structures were obtained and characterized in detail by taking (DODA)(12)H[Eu(SiW(11)O(39))2] (SEC-1) as an example. Optical microscope, atomic force microscopic, and scanning electron microscopic measurements confirmed the formation of three-dimensional microporous structure, in which the top surface shows a highly ordered honeycomb structure. As compared to common solvent-casting films, the corresponding honeycomb films are more hydrophobic and possess more ordered lamellar structures. Both the wettability and the size of SECs exert significant influence on the formation of microporous structures. The proper hydrophobicity of SECs was proposed to be an essential factor for the formation of honeycomb films, and large-sized SECs are favorable for the fabrication of highly ordered honeycomb structures. The conditions for the formation of different surface morphologies have been discussed in terms of the contact angle of SECs at the interface between water and chloroform, and a contact angle slightly greater than 90 degrees is found to be a prerequisite for the formation of honeycomb structures. The results reported in this paper not only help to further comprehend the mechanism of the formation of honeycomb structures, but also provide some guidance for the design of ordered microporous films based on organic/inorganic hybrid materials, exemplified by the organic/nanoparticle complexes.

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PubMed2005

Self-assembled multibilayers of europium alkanoates: structure, photophysics, and mesomorphic behavior.

A series of europium alkanoates (C(n-1)H(2n-1)CO(2))(3)Eu, (n = 14, 16, 18, 20) have been synthesized and characterized in detail. X-ray diffraction and Fourier transform infrared spectroscopic measurements confirm the multibilayer structure of these homologues. In such bilayers, the europium ionic layers are well separated by the highly ordered alkyl chains which are in an all-trans conformation and perpendicular to both sides of the europium ionic layers. There is a mixed-coordination type of chelating bidentate and bridging bidentate between the carboxylate groups and the europium ions. All samples exhibit characteristic emission of europium, though the luminescent intensity has been partly quenched by the carboxylate groups. Differential scanning calorimetry (DSC) shows multiple melting points for these homologues, and temperature-dependent X-ray diffraction measurements also confirm the existence of the mesophase on heating. This mesophase is not truly liquid crystalline, but is similar to the smectic A phase of organic rodlike molecules. Meanwhile, it seems that with increasing atomic number of lanthanide ions, longer alkyl chains will be required to form such a mesophase for the corresponding lanthanide alkanoates.

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PubMed2005

Polyoxometalate-based vesicle and its honeycomb architectures on solid surfaces.

The introduction of cationic surfactant DODA as counterions of [Eu(H2O)2SiW11O39]5- can form a mesoscopic supramolecular assembly of (DODA)4H[Eu(H2O)2SiW11O39], which aggregates into vesicles in chloroform. This POM-based vesicle can be further transferred into three-dimensional microporous architectures under moist air. The present methodology shows that, by combining inorganic chemistry and colloidal surface chemistry, a sequential self-assembling approach based on a series of linkable preorganized building blocks allows access to the fabrication of technological applicably POM-based microsized patterns, alternated with the soft lithographic method.

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PubMed2004

Surfactant-encapsulated polyoxometalloeuropate: polarized Eu3+ emission in the highly ordered self-organizing film.

An organic/inorganic composite, (DODA)(9)EuW(10)O(36).9H(2)O, can form a highly ordered self-organizing film with a layered structure and almost fully interdigitated alkyl chains at solid supports. EuW10O36(9-) is deduced to be oriented in its self-organizing film, resulting in its polarized emission, which offers an accessible approach to fabricating the functional thin films containing polyoxometalates.

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