Formation of insoluble perylenetetracarboxylic diimide films by electro- or photo-crosslinking of pyrrole units

Perylenetetracarboxylic diimide derivatives bearing 2- or 4-peripheral pyrrole pendants could be efficiently crosslinked to form an insoluble film either by electropolymerization or visible light induced oxidative photopolymerization of the pyrrole units.     

Supramolecular self-assembly study of a flexible perylenetetracarboxylic diimide dimer in Langmuir and Langmuir–Blodgett films

A novel perylenetetracarboxylic diimide molecule (2PDI-TAZ), which contains two perylenetetracarboxylic diimide (PDI) attached to a melamine headgroup, was designed and synthesized. Supramolecular self-assemblies were studied in Langmuir and Langmuir–Blodgett films. Surface pressure–area isotherm measurements and the spectroscopic studies indicate that the 2PDI-TAZ molecules adopted a face-to-face configuration and edge-on orientation in Langmuir or the multilayer LB films. The presence of the barbituric acid in subphase change the hydrophilicity of 2PDI-TAZ due to the hydrogen bonding between melamine and barbituric acid, which has been revealed by the π–A isotherms and the FT-IR spectra. Transmission electron microscopy images of the LB films deposited from the barbituric acid solution revealed uniform nanowire morphology while the X-ray diffraction studies indicate that the molecules in the solid film packed with high order. The strong excimer emission of 2PDI-TAZ in LB films suggests enforced face-to-face configuration for the PDI unites in LB films in relative to that in solution.     

Synthesis and aggregation behavior of perylenetetracarboxylic diimide trimers with different substituents at bay positions

Three perylene tetracarboxylic diimide (PDI) trimers substituted with different side groups at the bay positions were prepared with the triazine ring as a linkage. The free rotation of C-N-C bonds between the triazine ring and the PDI unit provide these molecules with some flexibility. The UV-vis absorption and fluorescence spectra of these three compounds show different concentration-dependent behaviors, which depend on the side groups at the bay positions. Significant aggregation in organic solvents was revealed by the electronic absorption and emission spectra as well as the fluorescence quantum yield calculation. The aggregation behavior of these compounds in the solid state were investigated by X-ray diffraction (XRD), and the morphology of the aggregates was examined by atomic force microscopy (AFM). The aggregation of trimer 1 with two phenoxy groups at the 1 and 7 positions results in long nanofibers whereas trimers 2 and 3 with dipiperidinyl groups or tetraphenoxyl groups at the bay positions form only particles. The results of this research revealed that PDI trimers with flexible structures can also self-assemble into large ordered aggregates such as those with rigid structure. This information is believed to be useful in the design of novel nanoorganic materials.     

Formation of a novel porphyrin-gold nanoparticle network film induced by IR light irradiation

IR light irradiation of a mixed toluene solution of ammonium salt-stabilized gold nanoparticles with 3.8 +/- 0.8 nm core diameter and a porphyrin thioacetate derivative affords a thin photoactive film of the cluster-porphyrin network.     

Synthesis and properties of perylenetetracarboxylic diimide dimers linked at the bay position with conjugated chain of different length

Three perylenetetracarboxylic diimide (PDI) dimers linked with a conjugated chain of different lengths have been designed and prepared. The UV-Vis absorption and fluorescence spectra of these three dimers revealed different photophysical properties owing to the different length of the linkage. The intermolecular π-π interactions were found to be enhanced significantly with the increase in the length of the linkage and therefore induced different aggregation behaviors of these molecules. The structure of the molecular aggregates was investigated by X-ray diffraction (XRD), and the morphology of the aggregates was examined by atomic force microscopy (AFM). One-dimensional fibers were observed for the aggregates of compounds 2 and 3, and thin solid films were observed for the aggregates of compound 1.     

Cobalt complexes of a selenium diimide and a tellurium diimide dimer

[CoCl₂{N,N′-Te₂(N^tBu)₄}] (1) was obtained in good yields by the reaction of equimolar amounts of (^tBu)NTe(μ-N^tBu)₂TeN(^tBu) and CoCl₂ in toluene under an argon atmosphere. The crystal structure of 1·CH₂Cl₂ showed that the dimeric tellurium diimide ligand is N,N′-chelated to cobalt. The related reaction of Se(N^tBu)₂ and CoCl₂ affords a green product tentatively identified as a 1:1 adduct [CoCl₂{N,N′-Se(N^tBu)₂}] (CHN analysis). However, recrystallization from thf produces the ion-separated complex [Co₂(μ-Cl)₃{N,N′-Se(N^tBu)₂}₂(thf)₂][CoCl₃{NH₂(^tBu)}]·1½thf (2·1½thf), in which the monomeric selenium diimide ligand is N,N′-chelated to cobalt in the cation. A pathway for the formation of 2 from [CoCl₂{N,N′-Se(N^tBu)₂}] in thf is proposed.     

Formation of charge states on the surface of a laminated polyimide-fluoropolymer film by glow- discharge treatment

The alteration of properties of both sides of the laminated polyimide-fluoropolymer film PMF-351 by treatment in a low-frequency glow discharge, depending on their position with respect to the electrode, was investigated. By the dynamic capacitance method, it was found that both positive and negative charges can be induced on both sides of the film modified in the cathode fall, depending on the arrangement of its polyimide and fluoropolymer sides with respect to the electrode. It was shown that the formation of a negative charge in PMF-351 is in all cases due to trapping of plasma electrons injected into the polymer surface layers.     

EQCM studies of composition and electrochemical performance of film prepared by electrochemical reduction of sodium ferrate

A solid film was prepared by electrodepositing on a gold-film-coated quartz crystal electrode in Na₂FeO₄ solution, and characterized in 1?M LiClO₄/propylene carbonate (PC) + 1, 2-dimethoxyethane (DME; 1:1 by volume) electrolyte using electrochemical quartz crystal microbalance (EQCM). The EQCM experimental and X-ray photoelectron spectroscopy results indicate that the composition of the electrodeposited solid film prepared in the potential range of 0.18 to ?0.57?V vs. Ag/AgCl is FeOOH; and almost 1?mol lithium ions can be intercalated into and then extracted from 1?mol FeOOH film during discharge/charge process in 1?M LiClO₄/PC + DME electrolyte. The discharge/charge experiment indicates that the specific capacity of FeOOH film stabilizes at a value close to its theoretical specific capacity after 20 cycles, and FeOOH film maintains a specific capacity of about 300?mAh?g^?1 at the end of 170 cycles. It is therefore concluded that the FeOOH film has a good electrochemical cycle ability in 1?M LiClO₄/PC + DME electrolyte.     

Formation of a novel electroactive film by electropolymerization of 5-amino-1-naphthol

The electrooxidation of 5-amino-1-naphthol in acetonitrile solutions led to the formation of a purplish gray, air-stable, polymeric film (poly(5-amino-1-naphthol), poly(5,1-ANT)), which presents a nonfibrillar morphology, on basal-plane pyrolytic graphite and In-Sn oxide conducting glass (ITO) electrodes. The film showed a reversible, well-defined oxidation-reduction response in both aqueous solutions of pH 1–13 and protic non-aqueous solutions, and was semiconducting. The formal redox potential (E^o') was 0.075 V vs. a sodium chloride saturated calomel electrode in 0.2 M NaClO₄ aqueous solution (pH 1.0). The pH dependence of (E^o') suggested that the electrode processes at pH 1-5 and pH 8–13 are 1e⁻ − 1H⁺and 1e^t- − 2 H⁺ reactions, respectively. The poly(5,1-ANT) film-coated ITO electrode displayed an electrochromic character: the oxidized form is purplish gray and the reduced one is pale brownish yellow. In addition, based on the electrochemical and IR absorption spectroscopic characterization of the film, some possible candidates for the structures of electroactive moieties of poly(5,1-ANT) are proposed.     

Ultrasensitive sensing of hydrazine vapor at sub-ppm level with pyrimidine-substituted perylene diimide film device

A pyrimidine-substituted perylene diimide (Pyrimidine-PDI), in which the electron-deficient N-heterocyclic pyrimidine rings were introduced into the core positions, were synthesized to produce a conductometric film device for the sensitive detection of hydrazine (NH₂NH₂) vapor at room temperature under ambient conditions. The Pyrimidine-PDI film device exhibited ultrafast response, excellent reproducibility, excellent selectivity and good long-term stability towards hydrazine vapor. The response and recovery time of the device was calculated to be very low as 0.4?s and 0.6?s for hydrazine vapor at sub-ppm level (0.1?ppm). Moreover, the effect of the film thickness, relative humidity and temperature on the sensing performance were also studied. To understand the sensing mechanism, the core-benzene group perylene diimide (Ph-PDI) was also designed as a comparison. The film devices of Pyrimidine-PDI and Ph-PDI to hydrazine vapor were investigated with UV–vis spectra and cyclic voltammetry, which indicated that the redox of PDIs played a critical role in the sensing process. The electrochemical properties also indicated that electron-deficient N-heterocyclic pyrimidine rings could effectively lower the LUMO energy level and improve the response of the device.     

The two-terminal equivalent network of a three-terminal electrochemical cell

The two-terminal equivalent network of a three-terminal electrochemical cell is derived. This reveals, in a particularly clear way, how various artefacts arise from the layout of the cell. It is found that the working electrode response appears in series with an inductive artefact, and both appear in parallel with a capacitive artefact. Advice is given on how to diminish the size of these artefacts.     

Formation of regular nanoscale undulations on a thin polymer film imprinted by a soft mold

We observed the formation of regular nanoscale undulations on a polystyrene film when imprinted by a soft poly(dimethylsiloxane) mold above the polymer's glass transition temperature. The shape of the wave was reminiscent of a buckling wave frequently observed for a metal film supported on an elastomeric substrate. We derived a simple theoretical model based on an anisotropic buckling of the polymer film rigidly bound to a substrate, which agrees well with the experiment.     

电化学方法分析铅阳极膜的相组成

本文提出使用线性电位扫描和电位衰退定性和定量分析铅在4.5mol·dm^-^3H2SO4(30℃)中形成的阳极膜的相组成并与现场X射线衍射, 原子吸收光谱, 阳极溶出等法比较。结果表明电位扫描伏安曲线的峰电位和电位扫描至峰电位左右时电极开路后, 所得的稳定电位可用于阳极膜相组成的定性分析, 电位扫描伏安电线电流峰的面积可用于阴极膜相组成的定量分析。本文的阳极膜由PbO·PbSO4, PbO2和PbOn(2>n>1)组成, 以PbO·PbSO4为主要成份。     

Flexible metal film with micro- and nanopatterns transferred by electrochemical deposition

A new method for patterning microstructure on metal film by electrochemical deposition is provided. The metal film with micropattern can be peeled off after the deposition by inter-medium layer of resistant molecules such as triglyceride. We can use the technology of electrochemical deposition to make the metal film possess different functions such as soft and bendable properties. We also give an example to get the protein pattern transferred on the metal film. So, this method can also provide a way for the fabrication of protein pattern on the chip.     

Analysis of haloacetic acid mixtures by HPLC using an electrochemical detector coated with a surfactant-nafion film

High pressure liquid chromatography (HPLC) using an electrochemical (EC) detector electrode of pyrolytic graphite coated with a film of ionomer Nafion and the water-insoluble surfactant didodecyldimethylammonium bromide (DDAB) was used to achieve separation and detection of all six bromo- and chloro-acetic acids. The Nafion-DDAB film preconcentrates the acid anions facilitating their electrochemical detection by direct reduction at -1.2 V versus SCE. Detection limits were poorer than the EPA-approved GC-ECD method, but HPLC-EC avoids the derivatization necessary for GC. The HPLC-EC method also detected tribromoacetic acid, which has not been determined simultaneously with other halogenated acids by reported chromatographic methods. The HPLC-EC method using a Nafion-DDAB-coated detector electrode gave comparable results to GC-ECD for the determination of TCA in drinking water.     

Amperometric biosensors based on the immobilization of oxidases in a Prussian blue film by electrochemical codeposition

Prussian blue has been formed by cyclic voltammetry onto the basal pyrolytic graphite surface to prepare a chemically modified electrode which provides excellent electrocatalysis for both oxidation and reduction of hydrogen peroxide. It is found for the first time that glucose oxidase or -amino oxidase can be incorporated into a Prussian blue film during its electrochemical growth process. Two amperometric biosensors were fabricated by electrochemical codeposition, and the resulting sensors were protected by coverage with a thin film of Nafion. The influence of various experimental conditions was examined for optimum analytical performance. The glucose sensor responds rapidly to substrates with a detection limit of 2 × 10⁻⁶ M and a linear concentration range of 0.01–3 mM. There was no interference from 2 mM ascorbic acid or uric acid. Another ( -amino acid) sensor gave a detection limit of 3 × 10⁻⁵ M -alanine, injected with a linear concentration range of 7.0 × 10⁻⁵-1.4 × 10⁻² M. Glucose and -amino acid sensors remain relatively stable for 20 and 15 days, respectively. There is no obvious interference from anion electroactive species due to a low operating potential and excellent permselectivity of Nafion.     

Room temperature deposition of nanocrystalline cadmium peroxide thin film by electrochemical route

Nanocrystalline cadmium peroxide thin film has been electrodeposited on indium doped tin oxide glass substrate from aqueous solution at room temperature. The grain size of the nanocrystals of the film is estimated from XRD and is about 14 nm. The deposits are decomposed at 228 °C by formation of CdO, releasing plentiful heat at same time. The band-gap of the nanocrystalline CdO film made from decomposition of electrodeposited CdO₂ is around 2.4 eV.     

聚苯胺分子印迹膜电化学传感器检测氯霉素

以苯胺为功能单体和交联剂,氯霉素(chloramphenicol,CAP)为模板分子,采用电化学聚合法(循环伏安法)在金电极上合成了对CAP具有快速响应能力的聚苯胺分子印迹膜;结合差示脉冲伏安法建立了针对氯霉素的检测方法,并将所制备的聚苯胺分子印迹膜用作电化学传感器以测定氯霉素眼药水中的氯霉素.结果表明,所制备的聚苯胺分子印迹膜具有制备简单、响应快速、灵敏度高、再生性能良好等特点;其对氯霉素眼药水中的氯霉素的检测结果令人满意,有望用于实际样品中氯霉素的检测.     

Zein film as a novel natural biopolymer membrane in electrochemical detections

Permselective modifier films are very important in preparing highly sensitive electrochemical sensors. In this work, for the first time, the behavior of gold and glassy carbon electrodes coated with biocompatible zein film as a permselective membrane for the electrochemical detection of various compounds has been investigated. For this purpose, several electroactive cationic (methylene blue, brilliant green, and thionine) and anionic (potassium ferricyanide, alizarin red S, and riboflavin-5’-phosphate) compounds have been used as model. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that zein membranes prepared from casting solution containing 1% zein in ethanol/water have porous structures with high nanometric roughness. The capacitance values of electrical double layers of electrodes modified with zein film were very high for hydrophilic ions in comparison with hydrophobic ions. Point of zero charge pH (pH_pzc) of zein membrane was 4.8. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) as well as pH_pzc study indicated that zein permselective membrane acts as ion exchanger film for selected cationic compounds with fast electrochemical kinetics responses in aqueous solution (pH=7). This behavior was confirmed by circulating solutions containing model compounds from homemade continuous cell equipped with polyamide membranes modified with zein film.

Graphical Abstract

     

Preparation of a mercury film electrode modified by tri-n-octylphosphine oxide and the electrochemical properties of this electrode

Mercury film electrodes have been prepared on silver metal and silver-coated glassy-carbon supports and have been modified by a film of tri-n-octylphosphine oxide (TOPO) in a poly(vinyl chloride) matrix. The electrodes have been characterized in detail and the effects of the modifying film parameters on their electrochemical properties have been studied. It has been shown that these electrodes permit selective and sensitive determinations of many metals. The most important parameters are the thickness of the modifying film, the modifier-to-matrix ratio in the modifying film and the base electrolyte composition. Data concerning the reactions of a number of metal ions on the modified electrode are given.