Studies of molecular recognition mechanism in supramolecular system of ruthenium(II) polypyridyl complexes and DNA

The recent studies on supramolecular system assembled by Ru(II) polypyridyl complexes and B-form double-stranded DNA is reviewed. These complexes have been studied as DNA spectroscopic tags and structural probes. The studies focus on the recognition parameters of these complexes binding to DNA, including the influence of the shape and size of intercalative ligand, the ancillary ligands and the effects of hydrogen bonding. Enantioselectivities of these complexes binding to DNA are also briefly discussed.     

Novel Cu (II) magnetic ion imprinted materials prepared by surface imprinted technique combined with a sol-gel process

A novel Cu (II) magnetic ion-imprinted polymer (MIIP) was synthesized by surface imprinting technique combined with a sol-gel process. The adsorbent of Cu (II)-MIIP shows higher capacity and selectivity than that of magnetic non-imprinted polymers (MNIP). Adsorption capacities of Cu (II)-MIIP and MNIP are 24.2 and 5.2 mg/g for Cu (II) ions, respectively. The selectivity coefficients of the Cu (II)-MIIP for Cu (II)/Zn (II) and Cu (II)/Ni (II) are 91.84 and 133.92, respectively. Kinetics studies show that the adsorption process obeys pseudo-second-order rate mechanism with an initial adsorption rate of 132.48 for Cu (II)-MIIP and 2.41 mg g⁻¹ min⁻¹ for MNIP. In addition, no obvious decrease was observed after up to five adsorption cycles, indicating that the Cu (II)-MIIP is of high stability.     

Preparation and optical properties of silica gels doped with a new Eu(III) complex

The preparation and incorporation in silica gels of a novel europium complex, [Eu(ntac)₃][pphendcn] containing 4,4,4-trifluoro-1-(naphthalene-2-yl) butan-1,3-dione (Hntac) and pyrazino[2,3-f][1,10-phenathroline-2,3-dicarbonitrile (pphendcn) is demonstrated. An effective energy transfer from the organic ligands to the Eu(III) ions leads to a strong f-f luminescence even at low activator concentrations, n_Eu/n_Si ≈ 1 × 10⁻⁵. The new amorphous materials are characterized by UV/Vis reflectance and transmission spectroscopy, luminescence/excitation spectroscopy, X-ray diffraction, elemental analysis, IR spectroscopy, DTA/TG and NMR. The optical properties of gels with a different Eu(III) doping are discussed. The stability of the europium complex in the silica matrix during time (up to 4 months) and after heating is discussed. The Eu(III) spectra-structure correlation is used to characterize the site symmetry of the activator.     

Zirconia-based luminescent organic-inorganic hybrid materials with ternary europium (III) complexes bonded

In this work, a novel red-emitting organic-inorganic hybrid material with europium (III) lanthanide β-diketonate complexes linked to a zirconia was reported, which was realized by adduct formation with zirconia-tethered terpyridine moieties. Luminescence enhancement of the hybrid material has been observed compared with pure Eu(tta)₃·2H₂O. Transparent and strongly luminescent thin films based on PMMA were also prepared at room temperature, which are highly luminescent under UV-light irradiation and possess a promising prospect in the area of optics.     

反应性钌(Ⅱ)-二亚胺类荧光指示剂的研究进展

为防止氧敏感荧光膜中荧光指示剂的流失,人们在荧光指示剂中引入反应性官能团,使指示剂分子化学键合到基材表面。概述了反应性钌(Ⅱ)-二亚胺络合物荧光指示剂的研究进展,包括反应性联吡啶、反应性邻菲咯啉配体的合成,反应性钌(Ⅱ)-二亚胺荧光指示剂的合成及其荧光特性。介绍了反应性钌(Ⅱ)-二亚胺类荧光指示剂在溶氧传感器中的应用研究。     

Preparation and properties of transparent conductive indium-tin-oxide/polyimide substrates via a sol-gel process

High temperature, flexible and colorless indium-tin-oxide (ITO) coated plastic substrates have been prepared from a series of thermally stable, high glass transition temperature (T_g) and colorless copolyimide films. The copolyimides were synthesized from 3,3′-diaminodiphenylsulfone, 9,9′-bis(4-aminophenyl) fluorene and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride monomers. Their T_gs were around 285-365 °C. The conductive ITO was synthesized by a sol-gel method, and then deposited onto the copolyimide films by a spin coating process. After thermal treatment at 300 °C under a nitrogen/hydrogen mixture gas for 24 h, the resistivity of the ITO film was 10⁻³ Ω cm, and its transmittance was 75% at the visible light region. Scanning electron microscopy and X-ray diffraction were used to observe the surface and morphology of the ITO films. UV-visible spectroscopy and the four-probe method were used to study their optical and electrical properties. The high performance ITO/plastic substrates can be used in the next generation flexible flat panel displays and solar cell.     

Syntheses of photo-active lead(II)-1,10-phenanthroline materials

A facile synthetic technique for the formation of high-purity, stoichiometric 1:1 and 1:2 molecular ratio photo-active materials of lead(II) bromide and lead(II) iodide with 1,10-phenanthroline is described. The method results in the formation of analytically high-purity crystalline materials which are light-sensitive but air-stable. Elemental analyses and X-ray powder diffraction were used to characterize the materials.     

Synthesis and luminescent properties of organic-inorganic hybrid macroporous materials doped with lanthanide (Eu/Tb) complexes

Visible luminescent macroporous materials covalently bonded with europium and terbium complexes were prepared using polystyrene spheres (PS) as the template. Both of the obtained terbium(Ш) macroporous material (Tb(Ш)-M) and europium(Ш) macroporous material (Eu(Ш)-M) exhibit close-packed spherical porous structure according to the SEM images. Furthermore, their BET surface areas were determined by the N₂ adsorption-desorption isotherms. The two samples show corresponding characteristic green and red luminescence, respectively. Moreover, IR spectra and photoluminescence (PL) properties suggest that the Tb/Eu(Ш) ions were coordinated with organic group grafted on macroporous matrix. The luminescent lifetimes were also measured.     

Characterisation of sol-gel silica films doped with chromium (III) acetylacetonate

Sol-gel silica films doped with chromium (III) acetylacetonate were synthesised on aluminium substrate and characterised by IR and UV-vis reflectance spectroscopy to study localisation and thermal transformations of doping Cr(acac)₃ molecules. The involvement of CO groups of Cr(acac)₃ molecules into hydrogen bonding with silanol groups of silica film was found out. Removal of doping Cr(acac)₃ molecules located at the surface of the film was detected upon thermal treatment at 473 K because of their weak interaction with silica network. The process of elimination of acetylacetonate ligands from Cr(acac)₃ molecules located inside the film and H-bonded to silica network was accompanied by Cr (III) to Cr (VI) oxidation which completed at 613 K with the predominant formation of dichromate-like species.     

Functionalized cotton via surface-initiated atom transfer radical polymerization for enhanced sorption of Cu(II) and Pb(II)

The surface-initiated atom transfer radical polymerization (ATRP) was used to successfully prepare the aminated cotton and polyacrylic acid sodium (P(AA-Na))-grafted cotton for the efficient removal of Cu(II) and Pb(II) from aqueous solution in this study. The modified cotton surfaces were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The grafted long polymers with high density of amine and carboxyl groups on the cotton surfaces were responsible for the enhanced adsorption of heavy metals. The sorption behaviors including sorption kinetics, isotherms and pH effect were investigated. The sorption equilibrium of Cu(II) and Pb(II) was achieved within 1 h on the P(AA-Na)-grafted cotton, much faster than 8 h on the aminated cotton. According to the Langmuir fitting, the maximum sorption capacities of Cu(II) and Pb(II) on the P(AA-Na)-grafted cotton were 2.45 and 2.44 mmol/g, respectively, higher than many adsorbents reported in the literature. The P(AA-Na)-grafted cotton had better adsorption behaviors for Cu(II) and Pb(II) than the aminated cotton.     

Synthesis of Fe-Ti-MCM-48 from silatrane precursor via sol-gel process and its hydrothermal stability

A series of bimetallic Fe–Ti-MCM-48 materials was successfully synthesized via sol–gel method using cetyltrimethylammonium bromide (CTAB) as a template and silatrane, iron (III) chloride, and titanium (IV) isopropoxide as silica, iron, and titanium sources, respectively. Scanning electron microscopy (SEM) showed the truncated octahedron morphology of Fe–Ti-MCM-48.X-ray diffraction (XRD) patterns showed well-defined, order cubic mesoporous structures. X-ray fluorescence (XRF) revealed the total metal content of the final product. UV–visible absorption spectra confirmed both iron (Fe³⁺) and cerium (Ti⁴⁺) species highly dispersed in the framework, while N₂ adsorption/desorption measurements indicated a high specific surface area. As metal content increased, the mesoporous order and surface area decreased. The synthesized Fe–Ti-MCM-48 with 0.01Fe/Si and 0.01Ti/Si ratio still retained a cubic structure after hydrothermal treatment at 100 °C for 72 h.     

Synthesis of crystalline MgO nanoparticle with mesoporous-assembled structure via a surfactant-modified sol-gel process

Highly crystalline MgO nanoparticles with the mesoporous-assembled structure were synthesized via a modified sol-gel process with the aid of a structure-directing surfactant under mild conditions. X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected-area electron diffraction (SAED) analyses revealed that the synthesized MgO possessed high crystallinity with the particle size in nanosized range. N₂ adsorption-desorption and pore size distribution analyses indicated that its pore size distribution was in a narrow mesoporous range, which originated from an assembly of the MgO nanoparticles.     

Fabrication and characterization of molecular hybrid materials with lanthanides covalently bonded in silica via sol-gel process

Tetraethoxysilane (abbreviated as TEOS) and a kind of monomer (abbreviated as PMA-APES) derived from modifying phenylmalonic acid with double carboxylate groups (abbreviated as PMA) with (3-aminopropyl)triethoxysilane (abbreviated as APES) were used as the inorganic and organic compounds respectively. Coordination reaction between lanthanides and the two -CO groups of the monomer happened simultaneously. The resulting material exhibits strong red-colored fluorescence (Eu³⁺) and green-colored fluorescence (Tb³⁺), suggesting the intramolecular energy transfer caused by coordination effect of the organic counterpart. IR, NMR, UV/vis absorption, low-temperature phosphorescence and fluorescence spectroscopy were applied for characterization of the material and the above spectroscopic data revealed that the triplet state energy of organic ligand matches with the emissive energy level of europium and terbium ions and effective intramolecular energy transfer process in these molecular hybrid systems.     

Nickel (II) ions sensing properties of dimethylglyoxime/poly(caprolactone) electrospun fibers

A novel dimethylglyoxime (DMG)/poly(caprolactone) (PCL) blend was electrospun into fibers to serve as an optical sensor for the nickel detection based on the formation of a red Ni(DMG)₂ complex. DMG was mixed with PCL at 10, 20 and 30% (w/w) in a mixture of N, N-dimethylformamide (DMF) and dichloromethane (DCM) (50/50, v/v) prior electrospunning process. The best fibers were prepared under an electric field of 20 kV and a distance between needle and collector of 20 cm. From scanning electron microscopy (SEM), the average diameter of the fibers remained nearly constant with increasing amount of DMG. The optimum mass ratio of DMG and PCL was found to be 20:80 as it produced fibers with the smallest diameter distribution and the best sensing property. The formation of the Ni(DMG)₂ complex was confirmed by Fourier transform infrared spectroscopy (FT-IR). The colorimetric response of the PCL/DMG electrospun fibers were then tested against the nickel ions over a concentration range of 1-10 ppm using reflectance spectroscopy. Good linearity between the reflectance values at 547 nm and the concentrations was obtained (R² = 0.9925). These proposed DMG and PCL fibers could be used as the naked-eye sensor for nickel in waste water.     

Ferroelectric properties of Pb(Zr,Ti)O3 films fabricated using a modified sol-gel based process

Ferroelectric PZT(20/80) thick films were fabricated by the screen printing method. And the PZT precursor solution was spin-coated on the PZT thick films to obtain a densification. Electrical properties of the thick films as a function of the firing temperature of the PZT precursor solution were investigated. The thickness of all thick films was approximately 60-62 μm. The porosity increased with increasing the firing temperature of the sol, and the porous microstructure and some large pores were observed above 700 °C due to the PbO evaporation. The relative dielectric constant, remanent polarization and dielectric breakdown strength of the specimen fired at 650 °C were 222, 16.5 μC/cm² and 73 kV/cm, respectively.     

Synthesis of SiO2-polyacrylic acid hybrid hydrogel with high mechanical properties and salt tolerance using sodium silicate precursor through sol-gel process

SiO₂-polyacrylic acid hybrid hydrogel was synthesized using sodium silicate (SS) as precursor through sol-gel technology. The result showed a core-shell structure was formed with SiO₂ inner core and acrylic acid (AA) outer shell. The characteristics of the hydrogel were determined by FTIR and TEM. When the mol ratio of SS/AA was 0.13, the compressive strength of the hydrogel reached 45.6 kPa at 99.1% water content while the swelling ratio was 1017.2 g/g in deionized water. Moreover, a high salt tolerance was also obtained.     

Adsorption of Pb(II) and Cd(II) from aqueous solutions using titanate nanotubes prepared via hydrothermal method

Titanate nanotubes (TNs) with specific surface areas of 272.31 m(2)g(-1) and pore volumes of 1.264 cm(3)g(-1) were synthesized by alkaline hydrothermal method. The TNs were investigated as adsorbents for the removal of Pb(II) and Cd(II) from aqueous solutions. The FT-IR analysis indicated that Pb(II) and Cd(II) adsorption were mainly ascribed to the hydroxyl groups in the TNs. Batch experiments were conducted by varying contact time, pH and adsorbent dosage. It was shown that the initial uptake of each metal ion was very fast in the first 5 min, and adsorption equilibrium was reached after 180 min. The adsorption of Pb(II) and Cd(II) were found to be maximum at pH in the range of 5.0-6.0. The adsorption kinetics of both metal ions followed the pseudo-second-order model. Equilibrium data were best fitted with the Langmuir isotherm model, and the maximum adsorption capacities of Pb(II) and Cd(II) were determined to be 520.83 and 238.61 mg g(-1), respectively. Moreover, more than 80% of Pb(II) and 85% of Cd(II) adsorbed onto TNs can be desorbed with 0.1M HCl after 3h. Thus, TNs were considered to be effective and promising materials for the removal of both Pb(II) and Cd(II) from wastewater.     

Biosorption of cadmium (II) and lead (II) from aqueous solutions using mushrooms: A comparative study

Sorption capacity of oyster mushroom (Pleurotus platypus), button mushroom (Agaricus bisporus) and milky mushroom (Calocybe indica) were evaluated on biosorption of heavy metals, viz. cadmium (II) and lead (II) from aqueous solutions. The optimum sorption conditions were studied for each metal separately. The desired pH of the aqueous solution was found to be 6.0 for the removal of cadmium (II) and 5.0 for removal of lead (II) for all the mushrooms. The percent removal of both the metals was found to increase with the increase in biosorbent dosage and contact time. The fitness of the biosorption data for Langmuir and Freundlich adsorption models was investigated. It was found that biosorption of cadmium (II) and lead (II) ions onto the biomass of the three mushrooms were better suitable to Langmuir than Freundlich adsorption model. P. platypus showed the highest metal uptake potential for cadmium (q_max 34.96 mg/g) whereas A. bisporus exhibited maximum potential for lead (q_max 33.78 mg/g). Milky mushroom showed the lowest metal uptake capacity for both the metals. The present data confirms that mushrooms may be used as efficient biosorbent for the removal of cadmium (II) and lead (II) ions from aqueous solution.