Synthesis and photophysical properties of conformationally fixed tricarbocyanines with phosphonate groups

A method for the synthesis of a series of symmetric and asymmetric conformationally fixed tricarbocyanines was developed based on benzоindolenine containing ethyl phosphonate and diethyl phosphonate groups in the linker at the quaternary nitrogen atom of the indolenine fragment. The polymethine chain meso position was modified by nucleophilic substitution of chlorine with O- and N-nucleophiles. Their absorption and fluorescence spectra were recorded, the possibility of further use of phosphonate-substituted tricarbocyanines as biomarkers was demonstrated. The dark cytotoxicity of synthesized compounds was studied, the possibility of their accumulation in HCT116, MCF7 cancer cells was shown.     

Capillary zone electrophoresis of graphene oxide and chemically converted graphene

The preparation of processable graphene oxide colloids called chemically converted graphene (CCG) involves the following steps: oxidation of graphite to form graphite oxide; exfoliation of graphite oxide to form graphene oxide (GO); and reduction of GO to form CCG. In this work, the exfoliation and reduction steps were monitored by capillary zone electrophoresis (CZE). CZE was performed in fused silica capillaries with UV absorbance at 230 nm (GO) and 270 nm (CCG) using 250 μM tetrapropylammonium hydroxide (pH 10.4). The results indicate that almost complete exfoliation of graphite oxide (0.05 wt%) and higher recovery of CCG were obtained by sonication at 50% power for more than 15 h. CZE is considered a valuable tool for the fractionation and analysis of GO nanoparticles and, hence, for the control of different steps in preparation of CCG.     

Double laminated reduced graphene/Cu_2S/reduced graphene/graphene oxide nanofilms and their photoelectrochemical properties

In this work,an efficient photocatalytic material was prepared directly on Indium tin oxide(ITO)glass substrates by fabricating Cu_2 S and graphene oxide onto graphene for photoelectrochemical(PEC) water splitting.The double laminated reduced graphene/Cu_2S/reduced graphene/graphene oxide(RG/Cu_2S/RG/GO) nanofilms were characterized,and an enhanced photoelectrochemical response in the visible region was discovered.The photocurrent density of the nanofilms for PEC water splitting was measured to be up to 1.98 m A/cm~2,which could be ascribed to the followings:(i) a higher efficiency of light-harvesting because of GO coupling with Cu_2 S that could broaden the absorbing solar spectrum and enhance the light utilization efficiency;(ii) a stepwise structure of band-edge levels in the Cu_2S/GO electrode was constructed;(iii) double laminated electron accelerator(RG) was used in the Cu_2S/GO materials to get better electron-injecting efficiency.     

Synthesis and photophysical properties of novel organic–inorganic hybrid materials covalently linked to a europium complex

A novel sol–gel derived hybrid material (classed as Eu-DBM-Si) covalently grafted with Eu(DBM-OH)₃·2H₂O (where DBM-OH = o-hydroxydibenzoylmethane) was prepared through the primary β-diketone ligand DBM-OH. All the synthesized ligands were characterized by ¹H NMR, elemental analyses and Fourier transform infrared spectra (FTIR). The resultant Eu-DBM-Si material exhibited good transparent and homogenous property. Compared to the Eu-DBM hybrid prepared by physically doped silicon dioxide with Eu(DBM-OH)₃·2H₂O, the Eu-DBM-Si hybrid presented more efficient ligand-to-Eu³⁺ energy transfer and a significant improvement in the measured emission quantum yield. Furthermore, the photophysical properties of these hybrid materials, such as the photoluminescence (PL) spectra, PL intensities, symmetry properties, lifetime decays, and Judd-Ofelt parameters were also investigated in detail.     

Model of the iron hydrogenase active site covalently linked to a ruthenium photosensitizer: synthesis and photophysical properties

A model of the iron hydrogenase active site with the structure [(mu-ADT)Fe2(CO)6] (ADT = azadithiolate (S-CH2-NR-CH2-S), (2: R = 4-bromophenyl, 3: R = 4-iodophenyl)) has been assembled and covalently linked to a [Ru(terpy)2]2+ photosensitizer. This trinuclear complex 1 represents one synthetic step toward the realization of our concept of light-driven proton reduction. A rigid phenylacetylene tether has been incorporated as the linking unit in 1 in order to prolong the lifetime of the otherwise short-lived [Ru(terpy)2]2+ excited state. The success of this strategy is demonstrated by comparison of the photophysical properties of 1 and of two related ruthenium complexes bearing acetylenic terpyridine ligands, with those of [Ru(terpy)2]2+. IR and electrochemical studies reveal that the nitrogen heteroatom of the ADT bridge has a marked influence on the electronic properties of the [Fe2(CO)6] core. Using the Rehm-Weller equation, the driving force for an electron transfer from the photoexcited *[Ru(terpy)2]2+ to the diiron site in 1 was calculated to be uphill by 0.59 eV. During the construction of the trinuclear complex 1, n-propylamine has been identified as a decarbonylation agent on the [(mu-ADT)Fe2(CO)6] portion of the supermolecule. Following this procedure, the first azadithiolate-bridged dinuclear iron complex coordinated by a phosphine ligand [(mu-ADT)Fe2(CO)5PPh3] (4, R = 4-bromophenyl) was synthesized.     

Elaboration of covalently linked polyoxometalates with ruthenium and pyrene chromophores and characteriation of their photophysical properties

Keggin and Dawson-type polyoxometalates (POMs) decorated by organometallic [cyclometalated ruthenium(II) polypyridine complex] or organic (pyrene) chromophores were prepared by postfunctionalization of hybrid disilylated POM platforms. The connection is made in a very efficient and modular way via Sonogashira coupling reactions, which provide a rigid linkage between the POM and the photoactive centers. Electronic properties have been inferred from electrochemical and photophysical studies and reflect poor electronic interactions between both partners. The presence of the POM leads to luminescence quenching of the chromophores, which was attributed to an intramolecular electron transfer from the chromophore to the POM. The rate of this process is much faster in the POM-pyrene than in the POM-Ru system. It depends on the driving force dictated by the redox potentials of both partners but also in the case of the POM-Ru system on the presence of the metallacycle, which acts as a molecular insulator and delays the intramolecular electron transfer. In the POM-Ru system, a comparative study of the luminescence quenching showed that the electron transfer is still more important in the covalently bonded hybrids than in systems where the POM and the ruthenium complexes are assembled via electrostatic interactions.     

氧化石墨烯-富里酸复合光催化剂的制备与分析

以氧化石墨烯作为载体,通过一种方便的自组装方法将富里酸分子固定在氧化石墨烯上,合成新型复合光催化材料GO-FA,并通过SEM、XRD、XPS等一系列的分析手段对其进行表征测试.同时,以尼泊金甲酯模拟废水,结合自由基捕获试验对降解机理进行探讨并进行对不同降解影响因素进行探究.表征结果显示富里酸颗粒包裹在氧化石墨烯表面,表...     

Preparation and photophysical properties of thin films of coumarin dyes

The results from investigating the photophysical properties of new coumarin dyes synthesized and incorporated into Langmuir-Blodgett films are presented. A method for forming monolayers on the surface of a water/air interface is proposed. The phase states of mixed monolayers on a water surface are studied. It is found that mixed monolayers of amphiphilic polyampholyte and dye allow us to obtain more stable and condensed films, relative to films of single components. The spectral and luminescent properties of synthesized dyes in solution and in Langmuir-Blodgett films are studied.     

Double laminated reduced graphene/Cu2S/reduced graphene/graphene oxide nanofilms and their photoelectrochemical properties

In this work,an efficient photocatalytic material was prepared directly on Indium tin oxide（ITO）glass substrates by fabricating Cu₂ S and graphene oxide onto graphene for photoelectrochemical（PEC） water splitting.The double laminated reduced graphene/Cu₂S/reduced graphene/graphene oxide（RG/Cu₂S/RG/GO） nanofilms were characterized,and an enhanced photoelectrochemical response in the visible region was discovered.The photocurrent density of the nanofilms for PEC water splitting was measured to be up to 1.98 m A/cm²,which could be ascribed to the followings:（i） a higher efficiency of light-harvesting because of GO coupling with Cu₂ S that could broaden the absorbing solar spectrum and enhance the light utilization efficiency;（ii） a stepwise structure of band-edge levels in the Cu₂S/GO electrode was constructed;（iii） double laminated electron accelerator（RG） was used in the Cu₂S/GO materials to get better electron-injecting efficiency.     

改性氧化石墨烯膜的制备及其性能研究

为了改善氧化石墨烯(GO)膜的低渗透性和不稳定性,本文采用过氧化氢对GO进行改性后抽滤成膜,并在不同温度下对膜进行热还原.采用超高性能全自动气体吸附仪、透射电镜、扫描电镜、拉曼光谱仪、接触角、X射线衍射等对材料进行结构和形貌表征.分析不同HGO(H2O2改性GO)负载量和不同温度热还原对膜水通量和截留率的影响.在优化条...     

Preparation of a poly(methyl methacrylate)-reduced graphene oxide composite with enhanced properties by a solution blending method

Poly(methyl methacrylate) (PMMA)/graphene nanocomposites were prepared by a simple solution blending method. The glass transition temperature of the produced PMMA/graphene composite was increased by 37 °C with 1.0 wt.% RGO content, which is approximately 40% of improvement compared to that of pure PMMA. The thermal expansion coefficient (TEC) decreased by 68% with as low as 0.1 wt.% RGO loading. The electrical conductivity of the nanocomposites reached up to 0.037 S/m even with only 2.0 wt.% RGO, which increased by more than twelve orders of magnitude. The resulting nanocomposites showed that a stable colloidal suspension of graphene dispersion in organic solvent before blending with PMMA is necessary to fabricate the nanocomposites with enhanced properties.     

Integration of supertetrahedral cluster with reduced graphene oxide sheets for enhanced photostability and photoelectrochemical properties

Supertetrahedral zinc-gallium-tin sulfide cluster modified with reduced graphene oxide protective layer was first synthesized, which exhibited an excellent photoelectrochemical performance and enhanced stability in comparison to supertetrahedral clusters.     

Preparation and photoelectrochemical characterization of nano-particulate TiO2 and polyaniline composite films on Au

TiO₂ and polyaniline(PANI) composite film was obtained by electrochemical methods^[1] and investigated for solar energy conversion application. A strong rectifying effect was found in the cyclic voltammogram of the film in dark when the scan speed was slow enough (5 mV/s) and a quasi-reversible voltammogram of the film was observed when the scan speed was fast (100 mV/s). The results of both the cyclic voltammograms and the SEM images of the composite film show that the PANI film is almost completely covered with nano-particulate TiO₂. Two anodic photocurrent bands and a cathodic band was observed in the spectra of the photocurrent of the TiO₂/PANI/PATP(p-aminothiophenol)/Au film in 0.05 mol/L Fe(CN)₆^3-/Fe(CN)₆^4- solution. The band at 300~400 nm (3.1~4.1 eV) can be ascribed to the photocurrent band of TiO₂ particles and the bands at 450~730 nm (1.7~2.8 eV) can be ascribed to those of the PANI. The partially-oxidized PANI has internal photoemission function and the insulating matrix of PANI is verified to be reduced PANI with a 3.33 eV bandgap energy. The flat-band potentials of partially-oxidized PANI and TiO₂/PANI composite film in 1.0 mol/LHClO₄ solution are determined as 0.87 V and 0.09(SHE) from Mott-Schottky plots, respectively.     

Diazonium functionalization of surfactant-wrapped chemically converted graphene sheets

Surfactant-wrapped chemically converted graphene sheets obtained from reduction of graphene oxide with hydrazine were functionalized by treatment with aryl diazonium salts. The nanosheets are characterized by X-ray photoelectron spectroscopy, attenuated total reflectance infrared spectroscopy, Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. The resulting functionalized nanosheets disperse readily in polar aprotic solvents, allowing alternative avenues for simple incorporation into different polymer matrices.     

石墨烯/还原氧化石墨烯/聚苯胺复合材料的制备及在超级电容器中的应用

本研究以低成本、易规模化的亲水性石墨烯/氧化石墨烯为前驱体,通过原位聚合的方法制备石墨烯/氧化石墨烯/聚苯胺复合材料,经过化学还原后制备得到石墨烯/还原氧化石墨烯/聚苯胺复合材料.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和傅里叶红外变化光谱仪(FT-IR)对制备的材料进行了结构和形貌的表征.运用循环伏安法...     

Preparation and photoelectrochemical performance of PbSe/BaTiO3/TiO2 composite film

By dipping-lifting in sol–gel solution and reducing process, the TiO₂ composite film on the glass plate was first prepared. Then, the PbSe/BaTiO₃/TiO₂ composite film was fabricated by interface reaction with BaTiO₃ and PbSe on the surface of TiO₂ composite film. The characterization results show that the uniform porous TiO₂ film is made up of the anatase crystal, and the PbSe/BaTiO₃/TiO₂ composite film is constructed by doping or depositing BaTiO₃ and PbSe nanoparticles on the surface of TiO₂ film. The photoelectrochemical measurement results indicate that the PbSe/BaTiO₃/TiO₂ composite film has an interesting photoelectrochemical conversion property.     

Linking photo- and redoxactive phthalocyanines covalently to graphene

"Green" graphene: For the first time, the covalent attachment of a light-harvesting and electron-donating phthalocyanine to the basal plane of few-layer graphene is reported. Physicochemical characterizations reveal an ultrafast charge separation from the photoexcited phthalocyanine to few-layer graphene followed by a slower charge recombination.     

Preparation and properties of diatomite composite superabsorbent

A novel diatomite composite superabsorbent was synthesized by solution polymerization of partially neutralized acrylic acid and diatomite, using N,N′-methylenebisacrylamide as a crosslinking agent and hydrogen peroxide and L -ascorbic acid as a redox initial system. The influences of some reaction conditions, such as diatomite content, neutralization degree of acrylic acid, amount of initiator, amount of crosslinking agent, monomer concentration, and the reaction temperature on swelling characteristic were investigated. The water absorbency of the sample prepared at optimum conditions was 99 g/g in 0.9 wt% NaCl solution. The results of swelling rate measurement showed that diatomite composite superabsorbent had better swelling rate than that of poly(sodium acrylate) prepared in the same conditions. Other properties, i.e. water retention, reswelling ability and resistance to salt, were also examined. Copyright © 2007 John Wiley & Sons, Ltd.     

Preparation and properties of macroporous superabsorbent composite

A fast swelling macroporous superabsorbent composite was prepared by the copolymerization of partially neutralized acrylic acid, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid (AMPS), and attapulgite (APT) using N, N′‐methylenebisacrylamide (NNMBA) and trihydroxymethyl propane glycidol ether as crosslinking agents. For fast swelling rate (SR), sodium bicarbonate, polyethylene glycol (PEG), and sodium carboxymethylcellulose (CMC) were introduced into the reaction system as foaming agent and stabilizers. Furthermore, the copolymer was surface‐crosslinked with glycerine and sodium silicate, and then blended with aluminum sulfate and sodium carbonate. The influences of the amount of NNMBA, trihydroxymethyl propane glycidol ether, PEG, CMC and sodium bicarbonate, and reaction temperature on water absorbence both under atmospheric pressure and load, and on the SR were investigated. The water absorbence of the sample in 0.9 wt% NaCl aqueous solution under atmospheric pressure and certain load (P ≈ 2 × 10³ Pa) could reach 54 and 8 g.g^?1, respectively, and the SR could reach 0.471 ml g^?1 s^?1. The excellent strength, resilience, and the dispersion of swollen hydrogel were also observed for the sample. Moreover, the surface morphology of macroporous superabsorbent composite was characterized using scanning electron microscope. Copyright © 2009 John Wiley & Sons, Ltd.