目视法检测阴离子用显色剂的研究进展

评述了以超分子化学分子识别为基础发展起来的新型阴离子目视显色剂,内容主要包括显色剂对选择性阴离子的显色属性以及显色属性和显色剂结构的关系.     

Characterization and Electroanalytical Application of ω-Mercaptoalkanesulfonic Acid Monolayers on Gold

Self-assembled monolayers (SAMs) of ω-mercaptoalkanesulfonic acid on gold surfaces have been studied by electrochemistry and other surface techniques. In spite of the fact that these monolayers are disorganized, i.e., of “brush” type, they are impermeable to inorganic anions due to their high negative charge. Moreover, we find that an ω-mercaptodecanesulfonic acid (MDS) monolayer is also impermeable to organic species, regardless of their charge, because of its high hydrophilicity. The combination of these properties made it possible to apply gold electrodes modified with MDS for the determination of iron(III) ions in the presence of organic species that are either electroactive throughout the same potential window or form strong complexes with iron(III).     

Synergistic Extraction of Am(III) and Eu(III) by Tris(2‐pyridylmethyl)Amine with Various Anions in 1,2‐Dichloroethane

The extraction equilibria of Am(III) and Eu(III) by using a tripodal ligand, tris(2‐pyridylmethyl)amine (tpa), with various lipophilic anions have been investigated. The extractability of both Am(III) and Eu(III) was increased by the combination of tpa and counteranions due to a synergistic effect. The separation factors between Am(III) and Eu(III) were also increased from 7.6 to 49 by the combination of counteranions and organic solvents. The extraction equilibria of Am(III) and Eu(III) with tpa in 1,2‐dichloroethane were determined by slope analysis. It was found that three anions and one molecule of the ligand coordinated to Am(III) and Eu(III) was extracted regardless of the anions.     

Electrochemical impedance spectroscopy of carboxylic-acid terminal alkanethiol self assembled monolayers on GaAs substrates

Adsorbate-induced charge depolarization can influence the organization of self assembled monolayers (SAMs) on semiconductor surfaces, especially as a function of the SAM functional group, SAM length and substrate dopant level and type. Based on systematic differences in the frequency response of the electrochemical impedance and phase data for carboxylic acid (COOH) terminal alkanethiol monolayers of varying alkane chain length assembled on GaAs substrates of different dopant level and type, we assessed the relative monolayer quality through fits to an appropriate equivalent circuit analog to compare the proportion of defects and SAM-induced semiconductor depolarization. At the open circuit potential in the NaCl-phosphate buffer, while SAMs on p+ GaAs were of marginally better quality than those on p GaAs, SAMs on n+ GaAs exhibited a far superior quality than those formed on n GaAs. COOH-terminal SAMs of longer chain lengths formed higher quality monolayers at all the substrate doping levels. COOH-terminal SAM modified n and n+ GaAs surfaces were passivated and stable over a wider voltage range than SAM modified p and p+ GaAs surfaces, from cyclic voltammetry. The poorer quality of COOH-terminal SAMs formed on GaAs substrates at the lower doping levels is attributed to the disorder as a result of the enhanced degree of charge depolarization at these surfaces, as substantiated by systematic variations in the space charge capacitance upon SAM modification that suggest a negative surface dipole.     

A genetically encoded pore for the stochastic detection of a protein kinase

Stochastic sensing is an emerging approach for the detection of a wide variety of analytes at the level of individual molecules. Detection is accomplished by observing the modulation of the current that flows through a single protein pore that has been engineered to bind an analyte of interest. Previously, protein analytes have been detected by using pores to which ligands have been appended at specific sites by targeted chemical modification. Here, we report the first genetically encoded stochastic sensor element for detecting a protein. A protein kinase inhibitor peptide sequence was incorporated into the alpha-hemolysin polypeptide, which was used to form a heteroheptameric pore containing a single copy of the inhibitor sequence. With this pore, the successful detection of the catalytic subunit of protein kinase A was demonstrated. This development should greatly facilitate the detection of active kinase subunits by stochastic sensing and the rapid screening of kinase inhibitors by an approach that yields kinetic information.     

Self-assembled bright luminescent hierarchical materials from a tripodal benzoate antenna and heptadentate Eu(III) and Tb(III) cyclen complexes

The europium heptadentate coordinatively unsaturated (Eu(III)) and the terbium (Tb(III)) 1,4,7,10-tetraazacyclododecane (cyclen) complexes 1 and 2 were used in conjunction with ligand 3 (1,3,5-benzene-trisethynylbenzoate) to form the supramolecular self-assembly structures 4 and 5;this being investigated in both the solid and the solution state. The resulting self-assemblies gave rise to metal centered emission (both in the solid and solution) upon excitation of 3, confirming its role as a sensitizing antenna. Drop-cased examples of ligand 3, and the solid forms of 4 and 5, formed from both organic and mixture of organic-aqueous solutions, were analyzed using Scanning Electron Microscopy, which showed significant changes in morphology;the ligand giving rise to one dimensional structures, while both 4 and 5 formed amorphous materials that were highly dense solid networks containing nanoporous features. The surface area (216 and 119 m2·g^-1 for 4 and 5 respectively) and the ability of these porous materials to capture and store gases such as N2 investigated at 77 K. The self-assembly formation was also investigated in diluted solution by monitoring the various photophysical properties of 3–5. This demonstrated that the most stable structures were that consisting of a single antennae 3 and three complexes of 1 or 2 (e.g., 4 and 5) in solution. By monitoring the excited state lifetimes of the Eu(III) and Tb(III) ions in H2O and D2O respectively, we showed that their hydration states (the q-value) changed from -2 to 0, upon formation of the assemblies, indicating that the three benzoates of 3 coordinated directly to the each of the three lanthanide centers. Finally we demonstrate that this hierarchically porous materials can be used for the sensing of organic solvents as the emission is highly depended on the solvent environment;the lanthanide emission being quenched in the presence of acetonitrile and THF, but greatly enhanced in the presence of methanol.     

Molecular adsorption of n-alkyl amines,carboxylic acids,and amides onto well-defined,polar organic surfaces

This paper details the formation of oriented monolayer films by the solution-phase adsorption of n-alkyl-chained adsorbates (CH₃(CH₂)_n-1Y) onto the polar surfaces of terminally-substituted self-assembled monolayers (SAMs; Au/S(CH₂)_mX). The polar tail groups (X and Y) of the adsorbate and SAM included amine, carboxylic acid, and amide groups, and the formation of the adsorbed monomolecular films on the SAMs relied on non-covalent interactions between X and Y. Highly organized monomolecular adlayers could be produced on the SAM surface that were as densely packed as the underlying alkanethiolate SAMs comprising the first layer. The quality of the adsorbed monolayers was related to the identities of the tail groups X and Y.     

芳香羧酸（苯基多羧酸）配合物研究进展

介绍了苯二甲酸、苯三甲酸、苯四甲酸等为配体的芳香羧酸配合物的配位模式,如苯二甲酸根据取代位置的不同,有对苯二甲酸,间苯二甲酸,邻苯二甲酸,与一元羧酸相比,配体中两个羧基的存在使得这些配体的配位模式更趋多样化,从而更有利于构筑高维结构的配位聚合物。综述了近几年芳香羧酸配合物的研究进展,表明芳香羧酸在组装超分子结构和合成配位聚合物方面有着突出的优势,特别是在金属有机配合物中占有重要地位。     

Electrochemical studies of self-assembled monolayers using impedance spectroscopy

Self-assembled monolayers (SAMs) using various organic molecules were constructed on thin thermal silicon dioxide on silicon structures. These structures have potential bio-applications. The monolayers are part of a capacitor sensor based on the electrolyte-insulator-silicon (EIS) structure. The main goal of this work is to investigate the ability of SAMs for acting as an intermediate layer between aqueous solutions and silicon based biosensors. This work presents monolayers based on trimethoxy silanes with various functional groups such as: (a) (3-aminopropyl)-trimethoxysilane, (b) octadecyltrimethoxysilane and (c) trimethoxy(3,3,3-trifluoropropyl)silane. The biosensor is a differential sensor with a built in reference based on the structure of electrolyte-insulator-silicon or in ion-sensitive-field-effect-transistors (ISFETs). While the methyl and fluorine groups can act as the reference part, which is passive to the bio-molecules detection, the capacitor containing the amine groups has the sensing capabilities to the biological molecules. The amine (NH₂) tail groups can be active for those attachments via glutaraldehyde.The film's study and characterization was made by spectroscopic ellipsometry, contact angle method (CA) and FT-IR spectroscopy. The electrical methods such as capacitance-voltage (C-V) and electrochemical impedance spectroscopy (IS) were used to investigate the whole electrolyte/SAM/SiO₂/Si structure. We will show the detection capabilities of these 2D structures, its electrical equivalent model through a simulation fitting and will discuss the application of those structures to bio-sensitive metal/oxide/silicon (MOS) devices.     

Iron oxide magnetic nanoparticles used as probing agents to study the nanostructure of mixed self-assembled monolayers

Self-assembled monolayers (SAMs) of organic molecules are of exceptional technological importance since they represent a convenient, flexible, and simple system for tuning the chemical and physical properties of surfaces. The fine control of surface properties is directly dependent on the structure of mixed SAMs which is difficult to characterize at the nanoscale with usual techniques such as scanning probe microscopies. In this study, we report on a general method to investigate at the nanoscale the structure of molecular patterns which consist in SAMs of two components. Iron oxide nanoparticles (NPs) have been used as probing agents to study indirectly the structure of mixed SAMs. Mixed SAMs were prepared by the replacement of mercaptododecane (MDD) adsorbed by mercaptoundecanoic acid (MUA) molecules on gold substrates. Therefore, the SAM surface displays both chelating carboxylic terminal groups and non-chelating methylene terminal groups. As NPs have been previously demonstrated to specifically interact with carboxylic acid groups, the increasing density in NPs was correlated with the evolution of the COOH/CH(3) terminal groups ratio. Therefore the structure of mixed SAMs was studied indirectly as well as the kinetic of the replacement reaction and its mechanism. With this aim, we took advantage of the SPR properties of the gold substrate and of the high refractive index of iron oxide nanoparticles to follow their assembling on mixed SAMs as a time resolved study. The high sensitivity and tuning of the SPR signal over a wide range of wavelengths are correlated with the NP density. Furthermore, SEM combined with image analysis has allowed studying the replacement rate of MDD by MUA in SAMs. We took also advantages of the magnetic properties of NPs to evaluate qualitatively the replacement of thiol molecules.     

Chemosensors for pyrophosphate

The selective detection of the anion pyrophosphate (PPi) is a major research focus. PPi is a biologically important target because it is the product of ATP hydrolysis under cellular conditions, and because it is involved in DNA replication catalyzed by DNA polymerase, its detection is being investigated as a real-time DNA sequencing method. In addition, within the past decade, the ability to detect PPi has become important in cancer research. In general, the sensing of anions in aqueous solution requires a strong affinity for anions in water as well as the ability to convert anion recognition into a fluorescent or colorimetric signal. Among the variety of methods for detecting PPi, fluorescent chemosensors and colorimetric sensors for PPi have attracted considerable attention during the past 10 years. Compared with the recognition of metal ions, it is much more challenging to selectively recognize anions in an aqueous system due to the strong hydration effects of anions. Consequently, the design of PPi sensors requires the following: an understanding of the molecular recognition between PPi and the binding sites, the desired solubility in aqueous solutions, the communicating and signaling mechanism, and most importantly, selectivity for PPi over other anions such as AMP and ADP, and particularly phosphate and ATP. This Account classifies chemosensors for PPi according to topological and structural characteristics. Types of chemosensors investigated and reported in this study include those that contain metal ion complexes, metal complexes combined with excimers, those that function with a displacement approach, and those based on hydrogen-bonding interaction. Thus far, the utilization of a metal ion complex as a binding site for PPi has been the most successful strategy. The strong binding affinity between metal ions and PPi allows the detection of PPi in a 100% aqueous solution. We have demonstrated that carefully designed receptors can distinguish between PPi and ATP based on their different total anionic charge densities. We have also demonstrated that a PPi metal ion complex sensor has a bioanalytical application. This sensor can be used in a simple and quick, one-step, homogeneous phase detection method in order to confirm DNA amplification after polymerase chain reaction (PCR).     

Factors Affecting on the Sorption/Desorption of Eu (III) using Activated Carbon

Abstract

The sorption and desorption of Eu (III) on H‐APC activated carbon using a batch technique has been studied as a function of carbon type, shaking time, initial pH solution, temperature, particle size of carbon, and concentration of the adsorbent and the adsorbate. The influence of different anions and cations on adsorption has been examined. The experimental data have been analyzed by Langmuir, Freundlich, and Temkin sorption isotherm models and the adsorption data for Eu (III) onto activated carbon were better correlated to the Temkin isotherm and the maximum absorption capacities obtained was 46.5 mg g^?1. Anions of phosphate, carbonate, oxalate, and acetate were found to increase the adsorption of Eu (III), whereas nitrate, chloride and all studied cations, potassium, sodium, calcium, magnesium, and aluminum have a negative effect on the adsorption capacity. More than 99% europium adsorbed on H‐APC eluted with 0.5 M HCl solution. The activated carbon prepared from apricot stone using 70% H₃PO₄ could be considered as an adsorbent that has a commercial potential for Eu (III) treatment.     

Selectivity of heavy metal ions at acidic supramolecular surfaces

Langmuir monolayers containing surface carboxylic acid head groups were examined in order to characterize their selectivity to metal ion adsorption. Experimental data of ion adsorption obtained by surface isotherms and FTIR spectroscopy were analyzed using a thermodynamic-and-electrochemical model. Among bivalent ions examined (Cr²⁺, Pb²⁺, Cu²⁺, Cd²⁺, Zn²⁺, Ca²⁺, Ni²⁺, and Ba²⁺), Langmuir monolayers showed the highest selectivity to chromium ions. In addition, it was found that adsorption constants of the surface ions are quite different from binding constants of the bulk ions. The results show important implications to sensing and separating metal ions by the use of acidic supramolecular materials.     

Functional Peptide Monolayers at Interfaces

Amphiphilic peptides can be designed to form ordered supramolecular structures at hydrophilic-hydrophobic interfaces. These systems rely on the ability of peptides to fold into certain secondary structures at interfaces. This review focuses on the design of amphiphilic β-sheet peptide assemblies in monolayers at interfaces, and their relevance to inducing mineralization and interactions with specific ions. In addition, the review discusses recent studies demonstrating the applicability of designed amphiphilic β-sheet peptides to detection of specific small molecules and to elucidating intermolecular interactions relevant to drug delivery and enzyme catalysis systems.     

Patterning Si by using surface functionalization and microcontact printing with a polymeric ink

This paper describes a simple procedure for patterning Si substrate using a combination of surface functionalization and microcontact printing(ΜCP). The Si/SiO₂ surfaces were chemically modified to present self-assembled monolayers (SAMs) of siloxanes terminating in reactive carboxylic anhydride groups and then patterned with poly(ethylene imine) (PEI) by, ΜCP We used the patterned thin films of PEI as etch resists on Si surfaces.     

Fabrication of Calix[]arene Derivative Monolayers to Control Orientation of Antibody Immobilization

Three calix[4]arene (Cal-4) derivatives which separately contain ethylester (1), carboxylic acid (2), and crownether (3) at the lower rim with a common reactive thiol at the upper rim were synthesized and constructed to self-assembled monolayers (SAMs) on Au films. After spectroscopic characterization of the monolayers, surface coverage and orientation of antibody immobilized on the Cal-4 derivative SAMs were studied by surface plasmon resonance (SPR) technique. Experimental results revealed that the antibody could be immobilized on the Cal-4 derivatives spontaneously. The orientation of absorbed antibody on the Cal-4 derivative SAMs is related to the SAM’s dipole moment. The possible orientations of the antibody immobilized on the Cal-4 derivative 1 SAM are lying-on or side-on, while on the Cal-4 derivative 2 and Cal-4 derivative 3 head-on and end-on respectively. These experimental results demonstrate the surface dipole moment of Cal-4 derivative appears to be an important factor to antibody orientation. Cal-4 derivatives are useful in developing site direct protein chips.     

Electrochemistry of conductive polymers: 41. Effects of self-assembled monolayers of aminothiophenols on polyaniline films

Effects of self-assembled monolayers (SAMs) of a few different aminothiophenols (ATPs) on growth, morphology, and electrical properties of polyaniline have been studied at gold electrodes employing current sensing atomic force microscopy. The 4-aminothiophenol (4-ATP) SAM showed the best capability of shuttling electrons from the gold electrode to the solution species, and the 4-ATP SAM covered electrode not only showed the best kinetics for the film growth but also produced the film of the highest electrical conductivity. The vertical conductivity of the film ranged from 58 S cm⁻¹ for a film prepared at a bare gold electrode to as high as 148 S cm⁻¹ for a film obtained at the 4-ATP SAM covered electrode. The conductivity was shown to depend on the thickness of the films as well as how they were prepared.     

Humidity sensing by luminescence of Eu(III)-doped mesoporous silica thin film

We report the luminescence properties of Eu(III)-doped mesoporous silica thin films (Eu-MSTFs) and their application to humidity sensing. Eu-MSTFs with ～9 nm-sized pores ordered into a wormlike pore structure were synthesized. The Eu(III) ions inside the pores could be coordinated with 1,10-phenanthroline or 2,5-pyridine dicarboxylic acid ligand by diffusing in the ligand molecules through the pores. The ligand molecules increased the luminescence intensity of the Eu(III) ions. The luminescence intensity of the ligand-treated Eu-MSTFs varied linearly with the humidity level in the environment. The humidity sensing by this method is repeatable over many times.     

Protection of self-assembled monolayers formed from triethyl phosphate and mixed self-assembled monolayers from triethyl phosphate and cetyltrimethyl ammonium bromide for copper against corrosion

Self-assembled monolayers (SAMs) of triethyl phosphate (TEP) and the mixed SAMs of TEP with cetyltrimethyl ammonium bromide (CTAB) were prepared on copper surfaces. The protection abilities of these films against copper corrosion in 0.2 M NaCl aqueous solution were investigated using electrochemical impedance spectroscopy (EIS) and polarization techniques. Results showed that the inhibition efficiency (IE) increased with an increase in the immersion time of copper in the TEP-containing solutions. When the TEP films were modified with CTAB, the ability of the corrosion inhibition of the mixed films improved markedly. Furthermore, the influence of an external magnetic field on the formation of SAMs was studied. Ab initio calculations were performed to provide some theoretical studies for our experiment.     

不同链长的烷基硫醇自组装膜在不同腐蚀介质中的抗腐蚀性阻抗研究

文章通过在铜表面上制备高质量的不同链长的烷基硫醇自组装膜并研究烷基硫醇自组装膜在不同腐蚀介质NaCl、HCl、H2SO4中的抗腐蚀能力,从而对其抗腐蚀性能进行比较研究。结果表明:铜电极上组装的C18SH、C12SH、C6SHSAMs在不同的腐蚀介质中对基底均有相当好的腐蚀保护作用;在其它条件相同的情况下,烷基硫醇的碳链越长,自组装膜对铜基底的腐蚀保护能力越强。