Publications

1996
Muskal N, Turyan I, Mandler D. Self-assembled monolayers on mercury surfaces. J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 1996;409 (1-2) :131 - 136.Abstract
The formation and organization of self-assembled monolayers of alkanethiols and ω-mercaptocarboxylic acids on Hg surfaces were studied. The organization process was examd. in-situ and ex-situ by cyclic voltammetry. Charging current measurements as well as electron transfer expts. with Ru(NH3)63+/2+ indicate that the adsorption of homologous alkanethiols and ω-mercaptocarboxylic acids on Hg is followed by the formation of a densely packed array. [on SciFinder(R)]
1995
Muskal N, Turyan I, Shurky A, Mandler D. Chiral Self-Assembled Monolayers. J. Am. Chem. Soc.Journal of the American Chemical Society. 1995;117 (3) :1147 - 8.Abstract
The organization of chiral self-assembled monolayers (SAMs) composed of a thiol deriv. of phenylalanine on a hanging mercury drop electrode (HMDE) has been studied. Comparing the excess of surface coverage of homo and heterochiral monolayers reveals that the latter are more densely packed. This was also supported by examn. the differential capacitance and the electrochem. behavior of an outer-sphere redox couple at surfaces covered by homochiral monolayers vs. monolayers based on the racemic mixt. [on SciFinder(R)]
Mandler D, Turyan I.; 1995. Determination of ultra low levels of mercury.Abstract
A highly specific and sensitive electrode for the detn. of ultra-low levels of Hg and an anal. system based on such electrode are described. The electrode is a glassy C electrode spin-coated with a monolayer of a highly sensitive reagent for the detection of Hg. The anal. method based on the use of this type of electrode is a voltammetric method. Concns. of the order of as low as ∼2 × 10-12 Mol Hg can be detected and measured. The reagent is 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo-[8.8.8]hexacosane. [on SciFinder(R)]
Meltzer S, Mandler D. Microwriting of gold patterns with the scanning electrochemical microscope. J. Electrochem. Soc.Journal of the Electrochemical Society. 1995;142 (6) :L82-L84.Abstract
The deposition of gold patterns on indium-tin-oxide (ITO) with the scanning electrochem. microscope (SECM) has been accomplished by the controlled dissoln. of a gold microelectrode. The continuous anodic dissoln. of gold at the microelectrode in the presence of bromide while maintaining the potential of the ITO const. resulted in the deposition of microcryst. structures of gold. The unique advantages of the SECM made it possible to suggest a mechanism for the process based on the structures as well as the parameters that control the deposition process. [on SciFinder(R)]
Meltzer S, Mandler D. Study of silicon etching in HBr solutions using a scanning electrochemical microscope. J. Chem. Soc., Faraday Trans.Journal of the Chemical Society, Faraday Transactions. 1995;91 (6) :1019 - 24.Abstract
The etching of silicon has been studied by the scanning electrochem. microscope (SECM) technique. Etching has been accomplished in acidic fluoride solns. by electrogenerating a strong oxidant, i.e. bromine in this case, at an ultramicroelectrode which was held closely above a silicon 〈111〉 wafer. The parameters that affect the process and control the efficiency of the silicon etching were examd. A detailed mechanism of the process, which was derived from the unique advantages of the SECM and is in agreement with previous reports, is proposed. [on SciFinder(R)]
Turyan I, Mandler D. Electrochemical study of the Cd(II)/Cd(Hg) system in 2-mercaptoacetic acid solutions. Electrochim. ActaElectrochimica Acta. 1995;40 (9) :1093 - 100.Abstract
A detailed study of the Cd(II)/Cd(Hg) system in 2-mercaptoacetic acid, H2MA, solns. was carried out in 1 M NaClO4 at pH 4.8-12.0. The electrochem. behavior of 2-mercaptoacetic acid at a dropping mercury electrode was studied as well. Since all complexes that are formed in the soln. undergo a reversible two-electron redn., math. anal. of the data, provided the compn. of the various complexes. The stability consts. of the following complexes: Cd(SCH2CO2)34-, Cd(SCH2CO2)22-, Cd(SCH2CO2), CdH(SCH2CO2)33-, CdH2(SCH2CO2)32-, CdH(SCH2CO2)2-, CdH2(SCH2CO2)2 and CdH(SCH2CO2)+ were detd. and their degree of formation as a function of pH were estd. The protonation consts. of the ligand were calcd. The H2MA forms extremely stable bidentate complexes with cadmium ions. The formation of the various complexes as a function of pH reveals that at pH 10.7-12.0 the complex Cd(SCH2CO2)34- predominates, whereas at pH 4.8-6.0 the complexes CdH2(SCH2CO2)2 and CdH(SCH2CO2)+ are dominant. At pH 6.1-10.6 different protonated and unprotonated complexes, composed of one to three ligands, coexist. [on SciFinder(R)]
Mandler D, Turyan I. Selective electrodes - quo va dis? Hakiyma'iy beYisra'elHakiyma'iy beYisra'el. 1995;14 :7 - 15.Abstract
Selective electrodes are electrochem. probes which are sensitive toward specific species. Most of these probes can be divided into two categories, i.e. potentiometric and voltammetric, based on the nature of the measurement. The major challenge is designing a selective electrode is introducing selectivity. The ultimate limit of their selectivity should make it possible to det. the levels of the analyte in unpolluted sea water. Through this manuscript two different approaches have been used as a means of developing voltammetric selective electrodes for heavy metals. The first concept involves the application of electrodes modified with crown ethers analogs. A selective electrode for gold ions was assembled by attaching an aza crown ether onto a glassy carbon surface. On the other hand an extremely sensitive electrode for mercury ions was developed based on a cryptand. Levels of mercury lower than 1 ppt could easily be detected using this probe. The electrode has been successfully applied for studying the release of mercury from dental amalgam. The second approach involves the formation of self-assembled monolayers with high affinity toward specific species. As an example, a selective electrode for cadmium ions is described. The electrode is made of ω-mercaptocarboxylic acid, HS(CH2)nCO2H, monolayers on mercury or gold surfaces. The detection limit of this electrode is 4 x 20̅12 M which is less than 1 ppt. The electrodes have been carefully studied and the parameters that govern their sensitivity as well as selectivity were optimized. Our major conclusion from this research is that very selective and sensitive probes can be developed by architecturing the solid-liq. interface at the mol. level. [on SciFinder(R)]
1994
Turyan I, Mandler D. Chemically modified electrode for the determination of gold - an electrochemical and spectrophotometric study. Fresenius' J. Anal. Chem.Fresenius' Journal of Analytical Chemistry. 1994;349 (7) :491 - 6.Abstract
The voltammetric detn. of trace amts. of gold was studied using a chem. modified electrode. The role played by the host mol. attached to a glassy carbon electrode (GCE), i.e. 8,9,17,18-dibenzo-1,7-dioxa-10,13,16-triazacyclooctadecane (DDTC), was examd. by electrochem. and spectrochem. techniques. Cathodic stripping voltammetry (CSV) was applied to study the various parameters affecting the affinity of gold ions by a DDTC modified electrode as well as the interferences by other ions. Finally, the method was successfully applied to det. gold traces in a geol. sample. In addn., the formation of an AuCl4--DDTC complex was followed and its formation const. was detd. by spectrophotometry. [on SciFinder(R)]
Shohat I, Mandler D. Deposition of nickel hydroxide structures using the scanning electrochemical microscope. J. Electrochem. Soc.Journal of the Electrochemical Society. 1994;141 (4) :995 - 9.Abstract
The scanning electrochem. microscope was applied to drive the deposition of Ni(OH)2 structures. Nickel hydroxide was deposited from aq. solns. onto platinum surfaces as a result of changing the pH locally on the electrode surface. The increase in pH is driven by an oxidn.-redn. process, i.e., N,N'-dimethyl-4,4'-bipyridinium, MV2+, which is reduced at an ultramicroelectrode, diffuses to the surface where it is regenerated upon the redn. of protons, causing a local increase of pH and the deposition of Ni(OH)2. The different parameters that control the efficiency of the deposition, such as the pH and the concn. of the buffer, were examd. [on SciFinder(R)]
Turyan I, Mandler D. Electrochemical determination of ultralow levels (<10-12 M) of mercury by anodic stripping voltammetry using a chemically modified electrode. ElectroanalysisElectroanalysis. 1994;6 (10) :838 - 43.Abstract
A glassy carbon electrode (GCE) coated with 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8.]hexacosane, Kryptofix-222, was used for the very sensitive and selective detn. of very low levels of mercury. A detection limit lower than 10-12 M (<0.2 ppt) was obtained applying anodic stripping voltammetry (ASV). The parameters that governed the sensitivity and possible interferences by other ions have been examd. in detail. The electrode has been successfully applied for detg. mercury in seawater, wastewater, and also in human saliva and amniotic fluid. The modified electrode exhibited high stability and, therefore, could be used repeatedly without mech. regeneration. [on SciFinder(R)]
Turyan I, Mandler D. Self-assembled monolayers in electroanalytical chemistry: Application of ω-mercaptocarboxylic acid monolayers for electrochemical determination of ultralow levels of cadmium(II). Anal. Chem.Analytical Chemistry. 1994;66 (1) :58 - 63.Abstract
Self-assembled monolayers of ω-mercaptocarboxylic acids, HS(CH2)nCO2H (n = 1, 2, 5, 10), on mercury film (MF) and gold electrodes have been used for the very sensitive and selective anal. of ultralow levels of cadmium(II). The authors find that shorter ω-mercaptocarboxylic acids provide superior sensitivity. Other parameters that govern the sensitivity and selectivity of this system have been examd. in detail. Optimizing these factors resulted in a detection limit of 4 × 10-12 M (0.45 ppt). The method has been verified by detg. cadmium in std. solns. and it has been successfully applied to the anal. of cadmium in seawater. [on SciFinder(R)]
1993
Turyan I, Mandler D. Electrochemical mercury detection. Nature (London)Nature (London, United Kingdom). 1993;362 (6422) :703 - 4.Abstract
Selective detn. of ultra low levels of mercury (<10-12M) is described using a glassy carbon electrode spin coated with 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix-222). The electrode was used for the detn. of mercury in sea water by anodic stripping voltammetry. [on SciFinder(R)]
Kaminsky A, Willner I, Mandler D. A reference electrode for organic solvent based on modified polyethylenimine loaded with ferricyanide/ferrocyanide. J. Electrochem. Soc.Journal of the Electrochemical Society. 1993;140 (3) :L25-L27.Abstract
A cross-linked polymer composed of polyethylenimine (PEI) reacted with 1,4-dibromobutane coated on a glassy C electrode (GCE) and contg. neg. charged ions, Fe(CN)63-/4-, is proposed as a ref. electrode in org. solvents. The system exhibits a relatively stable potential (±10 mV) over a period of several days in MeCN and a reasonable potential stability for several hours in DMF and CH2Cl2. The different parameters that affect the behavior of the GCE/PEI/Fe(CN)63-/4- are characterized. [on SciFinder(R)]
Malem F, Mandler D. Self-assembled monolayers in electroanalytical chemistry: application of ω-mercapto carboxylic acid monolayers for the electrochemical detection of dopamine in the presence of a high concentration of ascorbic acid. Anal. Chem.Analytical Chemistry. 1993;65 (1) :37 - 41.Abstract
Self-assembled monolayers of ω-mercapto carboxylic acids, HS(CH2)nCO2H (n = 2, 5, 10), Cm on gold electrodes were used as a means to induce electrochem. differentiation between a neurotransmitter, dopamine, and ascorbic acid. Optimum differentiation is found for n = 5, and it is attributed to a compromise between a well-organized system that requires long ω-mercapto carboxylic acids and a reasonable rate of electron transfer which is obsd. with short ω-mercapto carboxylic acids. [on SciFinder(R)]
Turyan I, Mandler D. Electrochemical determination of trace amounts of gold(III) by anodic stripping voltammetry using a chemically modified electrode. Anal. Chem.Analytical Chemistry. 1993;65 (15) :2089 - 92.Abstract
An electrochem. pretreated glassy carbon electrode (GCE) modified with an aza crown ether, 8,9,17,18-dibenzo-1,7-dioxa-10,13,16-triazacyclooctadecane (DDTC), has been used for the very sensitive and selective anal. of trace amts. of gold(III). A detection limit of 4.2 × 10-10 M was obtained by applying anodic stripping voltammetry. The parameters that affect the sensitivity and possible interferences by other ions have been examd. in detail. The modified electrodes exhibit high stability and, therefore, have been used repeatedly without mech. regeneration. Finally, the method has been successfully applied to det. gold traces in a geol. sample. [on SciFinder(R)]
Turyan I, Mandler D. Electrochemical mercury detection. Nature (London)Nature (London, United Kingdom). 1993;362 (6422) :703 - 4.Abstract
Selective detn. of ultra low levels of mercury (<10-12M) is described using a glassy carbon electrode spin coated with 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix-222). The electrode was used for the detn. of mercury in sea water by anodic stripping voltammetry. [on SciFinder(R)]
1992
Mandler D, KAMINSKI A, WILLNER I. Application of polyethyleneimine-quinone modified electrodes for voltammetric measurements of pH. Electrochim. ActaElectrochimica Acta. 1992;37 (15) :2765 - 7.Abstract
A modified polymer, i.e. benzylated polyethyleneimine (PEI), coated on a glassy C electrode in which neg. charged quinones were incorporated, was used for voltammetric measurement of pH. A linear dependence of the av. of the peak potentials as a function of pH was obsd. The system was successfully applied also to ultramicroelectrodes. [on SciFinder(R)]
Malem F, Mandler D. An easy method to prepare gold electrodes. J. Electrochem. Soc.Journal of the Electrochemical Society. 1992;139 (7) :L65.Abstract
An easy approach for constructing gold electrodes embedded in glass is described. A special "soft" glass, with a thermal expansion coeff. matching that of gold has enabled assembling gold electrodes which exhibit good sealing and thus excellent electrochem. response. [on SciFinder(R)]
1991
Mandler D, Bard AJ. The effect of tin(II) chloride adsorption on the electrochemical oxidation of tin(II) and other reactions at gold and platinum electrodes. J. Electroanal. Chem. Interfacial Electrochem.Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 1991;307 (1-2) :217 - 28.Abstract
During a study of the electrooxidn. of SnCl2 at Au and Pt electrodes by cyclic voltammetry, a remarkable hysteresis was assocd. with the oxidn. of SnCl2 that is attributed to the adsorption of SnCl2 on the Au electrode. The adsorbed SnCl2 inhibits the oxidn. of the bulk SnCl2 and therefore shifts the potential for oxidn. to more pos. values. However, once the adsorbed SnCl2 is oxidized, the dissolved SnCl2 is oxidizable at less pos. potentials. This inhibition by adsorbed SnCl2 also affects other inner-sphere electrode reactions (e.g., oxidn. of I-), but not outer-sphere reactions. This inhibition is explained in terms of the need of a bridging ligand to facilitate electron transfer in inner sphere reactions. This inhibition is even more pronounced on Pt electrodes, where no oxidn. wave for SnCl2 is obsd. However, adsorption of Cl- ions, 2-mercaptoethanol, or iodide causes desorption of the SnCl2 and the appearance of an irreversible wave for oxidn. of the Sn(II) in soln. [on SciFinder(R)]
1990
Mandler D, Bard AJ. High resolution etching of semiconductors by the feedback mode of the scanning electrochemical microscope. J. Electrochem. Soc.Journal of the Electrochemical Society. 1990;137 (8) :2468 - 72.Abstract
High resoln. (-μm£ etching of semiconductors has been achieved by applying the scanning electrochem. microscope (SECM) in the feedback mode. Strong oxidants, such as bromine, were electrogenerated in situ at an ultramicroelectrode UME and the surface. The variables that affect the size and shape of the etched pattern, the required properties of the redox couple, and the mechanism of the etching process are discussed. This approach was successfully applied to several III-V and II-V semiconductors: gallium arsenide, gallium phosphide, cadmium telluride, and mercury cadmium telluride. . [on SciFinder(R)]

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