Dengxu Wang

A 3D porous metal–organic framework constructed of 1D zigzag and helical chains exhibiting selective anion exchange

Slow diffusion of AgClO44 with Me2Si [(4-(Im-1-yl)Ph]2 (BIPS) yields the crystalline complex 1 with a 3D-braided porous metal–organic framework via self-assembly of two series of 1D polymer chains through both braiding and interpenetrating. Complex 1 consists of two distinct kinds of channels with different sizes and shapes along a and b directions occupied by perchlorate anions and water molecules.

Reactant ratio-modulated six new copper(I)–iodide coordination complexes based on diverse [CumIm] aggregates and biimidazole linkers: syntheses, structures and temperature-dependent luminescence properties

A total of six copper(I)–iodide coordination complexes with diverse [CumIm] aggregates and bidentate biimidazole bridging ligands, [Cu2I2(dmimb)]n (1), [Cu4I4(dmimb)]n (2), [Cu6I6(dmimb)3]n (3), [Cu4I4(dimb)]n (4), [Cu2I2(dimb)2]n (5), and [Cu4I4(dimb)3]n (6), (dmimb = 1,4-di(2-methyl-imidazol-1-yl)butane, dimb = 1,3-di(imidazol-1-yl)benzene), have been synthesized and structurally characterized by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Single-crystal X-ray diffraction analysis reveals that 1 is a double-chain based 1D ribbon incorporating a discrete [Cu4I4] stepped cubane aggregate. Complex 2 is a 2D layer based on the 1D infinite [Cu6I6]n column aggregate. Complex 3 is a triple-chain based 1D ribbon incorporating a discrete ladder-like [Cu6I6] aggregate. Interestingly, 1 and 3 are a pair of genuine supramolecular isomers controlled by the reaction ratio with an identical chemical composition. In the 2D layered structure of complex 4, the rare “S-shaped-double-bowl” Cu10I10 aggregate is observed and share the Cu2I2 rhomboids to form the 1D infinite [Cu10I10]n column. Complex 5 is a binuclear 18-membered metal–organic macrocycle with [CuI] monomeric units. Complex 6 is also a 2D layer constructed from a 1D infinite [Cu8I8]n aggregate which consists of a 1D infinite [Cu6I6]n column and a [Cu2I2]n ladder. In the overall view, the biimidazole linkers play an important role in the formation of diverse [CumIm] aggregates as well as the resulting structures and topologies. The structural changes of 1/2/3 and 4/5/6 are highly influenced due to the change of the reaction stoichiometry. For 1, 2, 5 and 6, they are non-emissive at both 298 K and 77 K, whereas 3 and 4 exhibit interesting temperature-dependent luminescence properties. The correlation between the luminescence thermochromism and the temperature-dependent variation of the Cu⋯Cu distance is also elucidated.

Solvent-controlled Cd(II) metal–organic frameworks constructed from a tetrapodal silicon-based linker

Two solvent-modulated Cd(II) metal–organic frameworks (MOFs), [Cd4(TCS)2(DMF)2(EtOH)(H2O)7·4DMF]n (1) and [Cd2(TCS)(DMF)2·4H2O]n (2) (H4TCS = tetrakis(3-carboxyphenyl)silicon, DMF = N,N-dimethylformamide), were constructed from a novel tetrapodal silicon-based linker. In 1 and 2, the TCS ligands exhibit different coordination modes and link mononuclear [Cd(COO)4] and tetranuclear [Cd4(COO)8(DMF)4] SBUs (secondary building units) to give 1 and 2 2D 44-sql net and (4,8)-connected 3D framework with rare fluorite (flu) topology, respectively. Dissimilarities in the geometry of both SBUs are originated from the different solvent systems which result in the formation of different networks in each case. The photoluminescence behaviours of them were also discussed.

Constructing hybrid porous polymers from cubic octavinylsilsequioxane and planar halogenated benzene

Heck coupling of cubic octavinylsilsequioxane (OVS) with planar di-/tri-halogenated benzene (1–5) results in a series of inorganic–organic hybrid porous polymers (HPPs). These materials show high thermal stability and tunable porosities with Brunauer–Emmett–Teller surface areas ranging from 479 m2 g−1 to 805 m2 g−1 and with the total pore volume ranging from 0.33 cm3 g−1 to 0.59 cm3 g−1. Porosity comparison reveals that monomer species and reaction conditions strongly affect the surface area, pore volume and microporosity. For the monomer species, monomers with high reactivity, long strut length and more connectable sites are beneficial to enhance the surface area and pore volume. For the reaction conditions, the conditions which can result in high levels of coupling degrees and the choice of N,N-dimethylformamide (DMF) as the solvent can also enhance the porosity. However, long monomer strut length may also lead to lower surface area and pore volume. DMF tends to increase the level of microporosity and increasing connectable sites may afford more mesopores. These results suggest that these comprehensive factors should be carefully considered when preparing new porous polymers with controllable porosity. In the application, HPP-3 possesses a moderate carbon dioxide uptake of 1.38 mmol g−1 (6.1 wt%) at 273 K and 0.68 mmol g−1 (2.99 wt%) at 298 K when measured up to 1 bar. HPP-3 shows a high binding ability with CO2 with an isosteric heat of 35 kJ mol−1 at low coverage, making these materials become promising candidates for storing and capturing CO2.

POSS-based luminescent porous polymers for carbon dioxide sorption and nitroaromatic explosives detection

Luminescent hybrid porous polymers (LHPPs) have been synthesized by the Heck coupling reactions of cubic octavinylsilsequioxane (OVS) and halogenated triphenylamine (TPA). The resulting materials show high thermal stability, and their porous and luminescent properties could be tuned by altering TPA species and reaction condition. The optimized polymer LHPP-3 exhibits high porosity with a Brunauer–Emmett–Teller surface area of 680 m2 g−1 and total pore volume of 0.41 cm3 g−1, and emits high yellow luminescence. LHPP-3 possesses a moderate CO2 uptake of 1.44 mmol g−1 at 273 K and 0.77 mmol g−1 at 298 K at 1.01 bar, suggesting these polymers could be utilized as adsorbents for CO2 storage and capture. Significantly, the luminescence of LHPP-3 could be quenched efficiently by nitroaromatic explosives such as 4-nitrotoluene, 2,4-dinitrotoluene and 2,4,6-trinitrotoluene, thereby indicating that the polymers could be utilized as chemical sensors for explosives detection.

Multifunctional alkoxysilanes prepared by thiol–yne “click” chemistry: their luminescence properties and modification on a silicon surface

The photoinitiated radical-based thiol–yne click reaction provides a simple and efficient method for the formulation of diverse alkoxysilanes. Seven alkoxysilanes, namely, 1,2-bis[3-(trimethoxysilyl)propylthio]hexane (T1), 1,2-bis[3-(trimethoxysilyl)propylthio]-3-chloropropane (T2), 1,2-bis[3-(trimethoxysilyl)propylthio]-3-bromopropane (T3), trimethoxy[3-(styrylthio)propyl]silane (T4), 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}hexane (D1), 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}-3-chloropropane (D2), and 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}-3-bromopropane (D3), were synthesized by reacting alkynes with 3-mercaptopropylalkoxysilane in the presence of a photoinitiator. The thiol–yne reactions ran neatly in standard glassware under 100 W UV irradiation. The functionalized trialkoxysilanes were obtained in quantitative to near-quantitative yields with high purity. Results showed that the reaction of synthesized T4 only occurred in the first cycle, and vinyl sulfide adduct was formed with two configurations of Z and E. Moreover, the isomerization of T4 from Z to E configurations was induced under UV irradiation. T1 and D1 showed excellent photoluminescence properties. Molecular calculations were also performed to confirm the experimental results. Computational results revealed that all compounds exhibited relatively large HOMO–LUMO band gaps, making them promising candidates as host materials for emitters and hole–electron blocking materials in OLED displays. In addition, T1, T2, and T3 were selected to modify the surface properties of Si (1, 0, 0), which can then be used for further functionalization or the immobilization of polymers or biomolecules.

Functional polysiloxanes: a novel synthesis method and hydrophilic applications

In this paper, functional dialkoxysilanes, (3-((3-chloropropyl)thio)propyl)methyldimethoxysilane, 3-((3-(dimethoxy(methyl)silyl)propyl)thio) propanoic acid, 3-methoxy-3-methyl-2,11-dioxa-7-thia-3-silatridecan-13-ol, and 3-methoxy-3-methyl-2,11,14,17,20,23,26,29,32-nonaoxa-7-thia-3-silatritriacontane, are first obtained by reacting functional alkenes with 3-(dimethoxy(methyl)silyl)propane-1-thiol in near-quantitative yields using a simple, efficient and photoinitiated thiol–ene click reaction. Then, functional polysiloxanes are synthesized from their corresponding functional dialkoxysilane monomers. This two-step method is a novel and efficient way of synthesizing functional polysiloxanes. The functional polysiloxanes show obvious fluorescence properties, which are assumed to be generated from unconventional chromophores. Furthermore, a series of copolymers (PETHs) with mercaptopropyl and polyether side chains are also obtained. They are successfully used for hydrophilic modification of a poly(styrene-b-butadiene-b-styrene) triblock copolymer. The PETH-based blue-light-emitting silicone elastomer is synthesized first via a thiol–ene click reaction, and it exhibits wonderful hydrophilicity, which may be useful in biomedical fields.

New Polyhedral Oligomeric Silsesquioxanes-Based Fluorescent Ionic Liquids: Synthesis, Self-Assembly and Application in Sensors for Detecting Nitroaromatic Explosives

In this paper, two different models of hybrid ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSSs) have been prepared. Additionally, these ILs based on POSSs (ILs-POSSs) exhibited excellent thermal stabilities and low glass transition temperatures. 1H, 13C, and 29Si nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to confirm the structures of the IL-POSSs. Furthermore, the spherical vesicle structures of two IL-POSSs were observed and were caused by self-assembly behaviors. In addition, we found it very meaningful that these two ILs showed lower detection limits of 2.57 × 10−6 and 3.98 × 10−6 mol/L for detecting picric acid (PA). Moreover, the experimental data revealed that the products have high sensitivity for detecting a series of nitroaromatic compounds—including 4-nitrophenol, 2,4-dinitrophenol, and PA—and relatively comprehensive explosive detection in all of the tests of IL-POSSs with nitroaromatic compounds thus far. Additionally, the data indicate that these two new ILs have great potential for the detection of explosives. Therefore, our work may provide new materials including ILs as fluorescent sensors in detecting nitroaromatic explosives.

Highly compression-tolerant and durably hydrophobic macroporous silicone sponges synthesized by a one-pot click reaction for rapid oil/water separation

We first report a novel and simple method for the synthesis of macroporous silicone sponges via a one-pot thiol-ene click reaction at −10 °C. The successful synthesis was confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The sponge has high porosity, low density, durable and high hydrophobicity, super-oleophilicity, good thermal insulation, and excellent compressibility (11.01 MPa at 93% strain, superior to those of all the previously reported silicone sponges) in addition to the conventional advantages of silicone such as non-flammability, excellent stability, and non-toxicity. The morphology, pore size, density, and compression properties of the sponge are also controllable by adjusting the synthesis conditions. Furthermore, the sponge could be used for rapid oil/water separation with good absorption ability, excellent reusability and separation efficiency (>99%).