Electrochemical study of some bromo-substituted [2.2]paracyclophanes

The potentials of electrochemical oxidation ( ) and reduction ( ) of monobromo- and isomeric di- and tribromo[2.2]paracyclophanes as well as of mono-, di-, and tribromobenzenes were measured in acetonitrile. The similarity between the properties ofpseudo-para-disubstituted cyclophanes andmeta-disubstituted benzenes, on the one hand, andpseudo-meta-disubstituted cyclophanes andpara-disubstituted benzenes, on the other hand, was confirmed by the existence of a linear relationship between of bromo-substituted [2.2]paracyclophanes and of the corresponding bromo-substituted benzenes. The results were explained in terms of the qualitative theory of molecular orbitals, taking into account a through space interaction between the -systems of the benzene rings.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 839–845, May, 1994.The authors wish to express their gratitude to Professor R. Hoffmann (Cornell University, USA) for a useful discussion and criticisms of the text of this paper.This work was financially supported by the Russian Foundation for Basic Research (Project 93-03-5246).     

Electrochemistry of metallofullerene films: the major isomer of Dy@C82

Solution-cast films of the major isomer of Dy@C(82) (Dy@C(82)(I)) have been studied by cyclic voltammetry (CV) in acetonitrile. The films are found to display pronounced and stable redox responses in solution. The reduction/reoxidation processes exhibit large splittings between the first two reduction and reoxidation waves. However, a pair of reversible oxidation and rereduction waves is observed after the reoxidation of a reduced film. The characteristics and the inter-relationship of these waves are uncovered by the CV technique, scanning electron microscopy (SEM), and UV/Vis-NIR spectra. A possible mechanism is proposed for the film electrode processes, which emphasizes the redox-induced structural reorganization of the metallofullerene film by the incorporation and expulsion of electrolyte ions into and out of the film. The influence of the counter ion diffusivity and the ion-pair stability on the electrochemical activity of the metallofullerene film has also been indicated.     

Potentiometric pH response of membranes prepared with various aminated-poly (vinyl chloride) products

The preparation and potentiometric pH response properties of membranes formulated with various aminated-poly(vinyl chloride) (PVC-NH₂) products are described. Products containing secondary and/or primary amino functional groups are obtained by modifying PVC with mono- and/or diamines, respectively. Blank membranes prepared with either type of aminated-polymer exhibit nearly Nernstian potentiometric pH responses over different pH ranges. In general, membranes based on diamino products exhibit pH response over a wider range (5–10.5) than membranes formulated with monoamino products (<8.0). These potentiometric results are used to estimate the basicity of the various primary and secondary amino sites in the membrane phases.Dedicated to Professer W. Simon on the occasion of his 60th birthday     

Direct Electrochemistry of Cytochrome c on EDTA-ZrO2 Organic-inorganic Hybrid Film Modified ElectrodesState Key Laborator3.＂ of Chemo／Biosensing and Chemometrics, Hunan Universit3; Changsha. Hunan 410082. China

A composite film of ethylenediamine tetraacetic acid (EDTA)‐ZrO₂ organic‐inorganic hybrid was prepared based on the chelation between Zr(IV) and EDTA. The direct electrochemical behavior of cytochrome c (cyt. c) at the hybrid film modified glassy carbon electrodes was investigated. The immobilized EDTA can promote the redox of heme in horse heart cyt. c which gives rise to a pair of reversible redox peaks with a formal potential of 40 mV (vs. SCE). The peak current increased linearly with the increase of cyt. c concentration in the range of 1.6 × 10^?6—8.0 × 10^?5 mol·L^?1 with the correlation coefficient of 0.996. Further investigation shows that metal ions can impede the electron transfer of cyt. c. The impediment capability of metal ions depends on their coordination capability with EDTA and their valence number.     

组合电化学--电化学研究中的新策略

组合电化学是一种新的电化学研究策略，通过设计和构建大量多样性的电极阵列，并对其进行高通量筛选和表征，快速、高效地实现了体系的电化学研究。本文综述了近年来进行的组合电化学研究，重点介绍了组合光学筛选方法、组合电化学合成方法以及电化学平行筛选方法，并探讨了各种方法的优势和存在的问题。     

Synthesis and fluorescence ion-sensory properties of the first dehydropyridoannulene-type cyclophane with enforced exotopic metal ion binding sites

The new twistophane 4 has been synthesised, which comprises a conjugated dehydropyridoannulene-type macrocyclic scaffold with outwardly projecting nitrogen-donor sites for the purpose of metal ion coordination. The macrocyclíc structure of 4 was assigned by using spectroscopic methods, and shown to exist in a twisted and chiral ground state conformation by semi-empirical theoretical calculations. A detailed spectroscopic investigation into the metal ion binding properties of 4 and precursor 11 revealed that they functioned as selective complexants, affording a fluorescence quenching output response characteristic of Pd(II) and Hg(II) ions. Furthermore, 4 also signalled the presence of Fe(II), Co(II), Ni(II) and Ag(I) ions by the precipitation of coordination polymers, and exhibited reversible proton-triggered fluorescence quenching behaviour. Macrocycle 4 thus represents a unique type of molecular sensory platform, which may find a wealth of potential applications such as the detection of heavy-metal pollutants, as well as for the fabrication of proton-switchable materials and coordination polymers with novel electronic and magnetic properties.     

Carbon‐based Nanosensors for Salicylate Determination in Pharmaceutical Preparations

Thiourea derivative‐based carbon paste electrode (TUD1‐CPE) was constructed as a potentiometric sensor for the determination of salicylate anion in pharmaceutical formulations, Aspocid® and Aspirin®. The optimized CPE contained 45.5 % graphite, 0.5 % reduced graphene oxide (rGO), 46.0 % nitrophenyl octyl ether (NPOE) plasticizer, 5.0 % TUD1 ionophore, and 3.0 % tridodecylmethyl ammonium chloride as additive. The incorporation of NPOE of high dielectric constant, and rGO in electrode caused better performance of the sensor; Nernstian response of 59.0 mV decade^?1 in the concentration range of 10^?1–10^?5 mole L^?1, a detection limit of 1×10^?5 mole L^?1 in a very short response time of 6 seconds. The prepared sensor showed high selectivity against similar anions (i. e. , benzoate, I^?, SCN^?). Selectivity was confirmed by calculating the formation constant (K_β) using sandwich membrane method, where K_β for TUD1‐salicylate is 10^0.43. Theoretical calculations at DFT‐B3LY/6‐31G** level of theory were performed to find interaction mechanism, Energies of HOMO and LUMO orbitals, non‐linear optical (NLO) properties (the electronic dipole moment (μ), first‐order hyperpolarizability (β), the hyper‐Rayleigh scattering (β_HRS) and the depolarization ratio (DR)), and other global properties; these calculations showed lower values of β and DR, higher value of β_HRS, and the shortest lengths of the four N?H bonds between TUD1 and salicylate which confirm their strong complexation and salicylate‐selectivity. Also, all the studied anion‐TUD1 exhibited relatively high NLO properties, and these results were considered as a preliminary study for investigating new types of NLO bearing materials. The sensors were applied successfully for the determination of salicylate anion in Aspocid® and Aspirin®.     

Creation of highly functional thin films using electrochemical nanotechnology

This overview describes the results of our recent study of the application of electrochemical nanotechnology to the fabrication of magnetic recording materials, interconnects in ultra-large-scale integrated (ULSI) devices, energy storage materials, and on-chip biosensors. It is important to note that electrochemical processes play significant roles in developing and fabrication such sophisticated materials and devices. In the field of magnetic recording, electrodeposition methods for preparing CoNiFe and CoFe soft magnetic thin films with a high saturation magnetic flux density were newly developed, and the significant issues for obtaining those films are highlighted. In the area of ULSI interconnects, we developed a technique using a self-assembled monolayer (SAM) for direct bonding of the interconnect layer to SiO2, and proposed a novel electroless deposition method for fabricating a diffusion barrier layer. In the field of batteries, electrodeposited SnNi alloy was proposed as a future anode material for Li batteries, and electrochemical MEMS processes were shown to be useful for fabricating micro-sized direct methanol fuel cells (DMFCs) as portable batteries for electronics applications. In the area of chemical sensors, we developed a new process for fabricating field effect transistors (FETs) modified with SAMs for on-chip biosensing applications.     

Analytical assays based on detecting conformational changes of single molecules.

One common strategy for the detection of biomolecules is labeling either the target itself or an antibody that binds to it. Herein, a different approach, based on detecting the conformational change of a probe molecule induced by binding of the target is discussed. That is, what is being detected is not the presence of the target or the probe, but the conformational change of the probe. Recently, a single-molecule sensor has been developed that exploits this mechanism to detect hybridization of a single DNA oligomer to a DNA probe, as well as specific binding of a single protein to a DNA probe. Biomolecular recognition often involves large conformational changes of the molecules involved, and therefore this strategy may be applicable to other assays.