bluuebunny/crossref_metadata_2025 huggingface dataset:
FDTD computation of electromagnetic fields caused by electrostatic discharge between charged metal spheres
Authors: Fujiwara Osamu , Okuda Koichi , Fukunaga Kaori , Yamanaka Yukio
Published: March 2003

In a discharge between charged metal spheres, the effect of the metal spheres on the generated electromagnetic field has not been clearly indicated. One of the authors (Fujiwara) has proposed the following computation method (called the image dipole method) for a spark discharge between metal spheres. The surface of the metal sphere is replaced by an infinite number of image charge pairs, which are arranged so that the surface is kept at the same potential. Then, the generated electromagnetic field is calculated analytically by superposition of the dipole fields caused by the spark current derived from the Rompe‐Weizel spark‐resistance law. It has been shown by the analysis that the metal sphere increases the field level. Then, the electromagnetic field generated by the spark discharge between metal spheres is calculated numerically by the finite‐difference time‐domain (FDTD) method, with the spark current as an excitation source for the metal sphere. The validity of the approach has been shown through comparison to the analytic solution by the image dipole method for the magnetic field waveform.

However, the above computation method has the problem that the static electric field before the onset of the discharge cannot be calculated, which makes it difficult to understand fully the ESD field produced by the charged metal bodies. In this paper, the generated electromagnetic field is calculated by the FDTD method (voltage source method), with the spark voltage derived from the spark‐resistor law as an excitation source. The result is compared to the results of calculations by the image dipole method and the current source method. It is shown that the waveform of the electrostatic field cannot be calculated by the current source method, but the voltage source method can calculate the field as in the case of the image dipole method. It is also seen that the magnetic field waveforms obtained by any calculation almost completely agree. The magnetic field waveform generated in the discharge experiment between metal spheres is observed by using a shielded magnetic field probe and a wideband oscilloscope (bandwidth 1.5 GHz), and is shown to agree almost completely with the results of calculations by the voltage source method and the image dipole method. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(7): 54–63, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1169
Subcodes constructed from bases of Reed‐Solomon codes
Authors: Fuwa Shigehide , Tanabe Hidehiko , Umeda Hiroyuki
Published: March 2003

This paper proposes a method of constructing nonlinear cyclic codes that form an additive group for which the decoding complexity or error correcting performance is improved relative to RS codes, which are typical linear cyclic codes. First, a code with information digit count k = 1 is constructed by using multiple RS code basis vectors obtained from Galois field Fourier transforms. Then, for k 1, codes are constructed from this code by using idempotent elements. Also, a code with code length n = 7 was constructed as an example, and both its minimal trellis diagram complexity and bit error rate on the AWGN channel due to a computer simulation were shown to be excellent. In addition, an iterative decoder was applied to the codes with k = 4 and 5, which had peak trellis diagram complexity, and it was shown that the decoding complexity could be reduced. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(7): 64–73, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1170
Glasses with Medical Applications
Authors: Vallet‐Regí María , Ragel C. Victoria , Salinas Antonio J.
Published: March 2003

Bioactive glasses react chemically with the body fluids. The reaction product is an apatite, which, with the intervention of biological drivers, assists the generation of bone matrix and bone growth. The main application of these bioactive glasses in the clinical field is the filling of osseous cavities, manufacture of small parts for middle ear bone replacement and maxilofacial reconstruction and dental applications. Thanks to advances in related medical technologies, bioactive glasses are now undergoing a new stage of development, resulting in different mechanical properties, drug delivery capabilities, bioactive coating of metallic implants, protein and/or cell activation for tissue regeneration and tissue engineering, and are also finding use in biomimetics, nanotechnology, production of hybrid organic‐inorganic materials and as bioactivity accelerators of mineral apatites or as bioactivity inductors of magnetic materials for hyperthermia treatment of osseous tumours. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
First Star‐Like Oligophenylene Molecules Containing a Dinuclear Organometallic Core
Authors: Chérioux Frédéric , Therrien Bruno , Süss‐Fink Georg
Published: March 2003

The cationic complexes Ru2[(p‐MeC6H4iPr)2(p‐SC6H4Br)3]+ and Rh2[(C5Me5)2(p‐SC6H4Br)3]+ are available in quantitative yields from the reaction of p‐HSC6H4Br with [Ru(pMeC6H4iPr)Cl2]2 and [Rh(C5Me5)Cl2]2 respectively. These complexes are found to undergo triple Suzuki coupling with oligophenylene boronic acids to give [Ru2(p‐MeC6H4iPr)2{p‐S‐(C6H4)n‐C6H5}3]+ and [Rh2(C5Me5)2{p‐S‐(C6H4)n‐C6H5}3]+ respectively. The star‐like trisbromo complexes are potential precursors for the insertion of dinuclear organometallic entities into the main chain of conjugated molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Nitric Oxide Reduction by Heme‐Thiolate Enzymes (P450nor): A Reevaluation of the Mechanism
Authors: Silaghi‐Dumitrescu Radu
Published: March 2003

The details of the heme‐thiolate nitric oxide reductase (P450nor) catalytic mechanism are still controversial. One theory, supported by computational results [D. L. Harris, Int. J. Quantum Chem. 2002, 88, 183−200], assumes two sequential one‐electron transfers from NAD(P)H to an initial [FeNO]6 complex. The [FeNO]8 species thus formed would react with NO, eventually liberating the unstable ONNO2− anion (most probably in its protonated form), which decomposes to N2O and water. However, more recent experimental results [A. Daiber et al., J. Inorg. Biochem. 2002, 88, 343−352] suggest the first committed step of the mechanism to be direct hydride transfer from NAD(P)H to [FeNO]6, presumably resulting in an iron‐bound HNO unit, [Fe‐(H)NO]8, that would be readily protonated to [Fe‐(H)NOH]8. Subsequent NO addition would yield the unstable HO‐N(H)‐N=O, which would dissociate from the heme and decompose to H2O and N2O. Here, the DFT geometry optimization of all previously proposed reaction intermediates is reported. The first step of the mechanism is predicted to be hydride transfer to [FeNO]6, to produce [FeNOH]8 or [Fe‐N(H)O]8. Subsequent addition of NO to [Fe‐NOH]8 (but not to [Fe‐N(H)O]8 or [Fe‐N(H)OH]8) is predicted to lead to immediate liberation of HN2O2−, without any stable intermediates. Contrary to what would be predicted according to the “thiolate push effect” dogma, the thiolate ligand at the heme active site is shown to obstruct NO reduction, rather than facilitate it. It is in fact shown that replacement of the thiolate by a neutral nitrogen ligand (i.e., lysine, as found in the active site of cytochrome c nitrite reductase, an enzyme that can reduce NO) clearly favors, from a thermodynamic point of view, NO reduction at the heme site. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Crystal and Electronic Structure of [Hg7As4](AgI3)2, a Novel Supramolecular Complex with the Off‐Plane AgI32− Guest Anion
Authors: Olenev Andrei V. , Baranov Alexei I. , Oleneva Olga S. , Vorontsov Ivan I. , Antipin Mikhail Yu. , Shevelkov Andrei V.
Published: March 2003

A novel supramolecular inorganic complex [Hg7As4](AgI3)2 has been prepared and its crystal structure determined. It crystallizes in the cubic system (space group Pa$\bar 3$
) with the unit cell parameter a = 13.138(1) Å and Z = 4. The crystal structure comprises a three‐dimensional positively charged host framework [Hg7As4]4+ with AgI32− guest anions trapped in each cavity of the framework. The guest anion shows an unusual off‐plane geometry (C3v symmetry), with a large, anisotropic thermal displacement parameter for the silver atom, which lowers significantly upon cooling from 293 down to 120 K. A study of the electronic structure shows that, although the host‐guest interaction is weak and diffuse, it governs both the geometry of the guest anion and its positioning within the framework cavities. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structural Investigation of the Thermal Decomposition of Ammonium Heptamolybdate by in situ XAFS and XRD
Authors: Wienold Julia , Jentoft Rolf E. , Ressler Thorsten
Published: March 2003

The decomposition of ammonium heptamolybdate (AHM, (NH4)6Mo7O24×4H2O) was studied in situ by X‐ray diffraction and X‐ray absorption spectroscopy, as well as by thermal analysis (TG/DTA). Decomposition conditions such as reactant atmospheres, (20% oxygen, 5% propene, 5% hydrogen, pure helium, and static air), heating rates, and gas flow rates were varied to investigate their influence on the decomposition process. The results obtained show that the reaction pathway is affected by the partial pressures of the gas‐phase decomposition products. The partial pressures of the decomposition products, water and ammonia, at a given temperature, is influenced mainly by the reactant gas flow rate and the heating rate. Lowering the partial pressures of ammonia and water inhibits the crystallization of the intermediate ammonium tetramolybdate (ATM), and promotes the formation of the intermediate hexagonal MoO3. The decomposition pathway under low gas phase product partial pressure is: (i) AHM; (ii) (ca. 335 K) X‐ray amorphous phase; (iii) (ca. 520 K) hexagonal MoO3; (iv) (ca. 650 K) the products, which depend on the reactant atmosphere, are mixtures of highly disordered Mo4O11, and/or α‐MoO3. Under different conditions the decomposition pathway is: (i) AHM; (ii) (ca. 350 K) X‐ray amorphous phase; (iii) (ca. 470 K) ATM; (iv) (ca. 570 K) hexagonal MoO3 + α‐MoO3; (ca. 650 K) α‐MoO3. Under a hydrogen containing atmosphere, a peculiar decomposition pathway is observed: an intermediate MoO3 with an unusual texture is formed prior to the reduction to MoO2 and the consecutive formation of orthorhombic Mo4O11. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
3‐Metalla‐1,2‐dioxolanes and Their Reactivity
Authors: Krom Monique , Peters Theo P. J. , Coumans Ruud G. E. , Sciarone Timo J. J. , Hoogboom Johan , ter Beek Sandra I. , Schlebos Paul P. J. , Smits Jan M. M. , de Gelder René , Gal Anton W.
Published: March 2003

The ethene complexes [MI(CH2CH2)]+ (M = Ir, Rh) can be oxygenated by molecular oxygen or air in the solid state, to form isolable unsubstituted 3‐metalla‐1,2‐dioxolanes [MIII(CH2CH2OO‐κ2C1,O2)]+. Such selectivity could not be achieved in solution. The stereoselectivity of the oxygenation process is highly dependent on the ligand, the metal and the counterion used. Oxygenation of [(tpa)M(CH2CH2)]PF6 {tpa = tri(2‐pyridylmethyl)amine; 4PF6, 7PF6} results in the formation of two isomeric 3‐metalladioxolanes, whereas oxygenation of [(tpa)M(CH2CH2)]BPh4 (4BPh4, 7BPh4) only yields one isomer. Furthermore, oxygenation of [(Metpa)Rh(CH2CH2)]PF6 {14PF6, Metpa = [(6‐methyl‐2‐pyridyl)methyl]bis(2‐pyridylmethyl)amine} proved to be much slower than that of [(tpa)Rh(CH2CH2)]PF6 (7PF6). The solid propene complex [(tpa)Rh(CH2CHCH3)]BPh4 (23BPh4) loses propene on reaction with molecular oxygen, and selectively forms the peroxo complex [(tpa)Rh(η2‐O2)]BPh4 (24BPh4). The obtained 3‐metalla‐1,2‐dioxolanes rearrange, both in the solid state and in solution, to formylmethyl hydroxy complexes on exposure to photons or protons. The isomeric 3‐rhoda‐1,2‐dioxolanes [(tpa)Rh(CH2CH2OO‐κ2C1,O2)]+ 8a+ and 8b+ differ in reactivity. On exposure of a solution of 8aPF6/8bPF6 to glass‐filtered daylight, isomer 8b+ rearranges to form the formylmethyl hydroxy complex 9b+. This rearrangement is three times faster than the rearrangement of 8a+ to 9a+. The iridadioxolanes are much more reactive than the corresponding rhodadioxolanes, whereas the iridium formylmethyl hydroxy complexes are less reactive than the corresponding rhodium formylmethyl hydroxy complexes. The tpa formylmethyl hydroxy complexes react reversibly with carbon dioxide to form formylmethyl hydrogen carbonate complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: Molybdenum Complexes with Linked Cycloheptatrienyl‐Phosphane Ligands and Their Use in Catalytic Carbon−Carbon Bond Formation
Authors: Tamm Matthias , Dreßel Bernd , Lügger Thomas , Fröhlich Roland , Grimme Stefan
Published: March 2003

The synthesis of P‐functionalized molybdenum chelate complexes incorporating the linked cycloheptatrienyl‐phosphane ligand [2‐(diisopropylphosphanyl)phenyl]cycloheptatrienyl (o‐iPr2P−C6H4−C7H6) is described. From the ligand precursor [2‐(cyclohepta‐2,4,6‐trienyl)phenyl]diisopropylphosphane (1) the paramagnetic 17‐electron dibromide [(o‐iPr2PC6H4‐η7‐C7H6)MoBr2(P−Mo)] (2) can readily be obtained. This is a versatile starting material for the preparation of cycloheptatrienyl molybdenum hydrides [(o‐iPr2PC6H4‐η7‐C7H6)Mo(η2‐BH4)(P−Mo)] (3) and [(o‐iPr2PC6H4‐η7‐C7H6)Mo(PPh3)H(P−Mo)] (4). Treatment of 3 with dimethylanilinium tetraphenylborate ([PhNMe2H][BPh4]) allows the production of the cationic 14‐electron complex fragment [(o‐iPr2PC6H4‐η7‐C7H6)Mo(P−Mo)]+ (13), which can be stabilized in the presence of suitable ligands L. The complexes [(o‐iPr2PC6H4‐η7‐C7H6)MoL2(P−Mo)]BPh4 [L = dimethylphenyl isocyanide, (5)BPh4; L2 = η4‐2,5‐norbornadiene, (6)BPh4; L2 = η2‐phenylacetylene, (7)BPh4; L2 = η2‐tert‐butylacetylene, (8)BPh4] can thus be isolated in good yields. The alkyne complex (7)BPh4 can be used as a single‐source catalyst for the oligomerization of phenylacetylene, affording a mixture of triphenylbenzenes and linear oligomers. Quantum chemical calculations reveal an intimate relationship between the catalytically active 14‐electron complex fragment [(o‐iPr2PC6H4‐η7‐C7H6)Mo(P−Mo)]+ (13) and hypothetical isoelectronic and isolobal complexes of the type [(o‐iPr2PC6H4‐η5‐C5H4)M(P−M)]+ (M = Ru, 14; M = Os, 15), indicating that cycloheptatrienyl molybdenum systems might in general be a suitable replacement for cyclopentadienyl ruthenium and osmium catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Modes of Reactivity of Cyclic Diynes: Probing the syn/anti Selectivity of Tetrathiacycloalkadiynes and Mono(alkyne)cobalt Complexes
Authors: Benisch Christoph , Werz Daniel B. , Gleiter Rolf , Rominger Frank , Oeser Thomas
Published: March 2003

Cyclic tetrathiaalkadiynes in which two 1,4‐dithiaalkyne units are connected with alkane bridges of length n and m [A(m.n)] were treated with [η2‐bis(tert‐butylsulfonyl)acetylene]carbonyl(η5‐cyclopentadienyl)cobalt(I) (8a) and several substituted analogues (8b−8e) in order to probe the reactivity of electron‐rich cyclic diynes. Both mono‐ [B(m.n)] and bis(cyclobutadiene) [C(m.n)] complexes were isolated as products of these reactions and the anti/syn ratio of C(m.n) was determined. For m, n < 4 the syn isomers dominate and this is attributed to the configuration of the intermediate metallacycle which is correlated with the conformations of the rings in the mono(cyclobutadiene) products B(m.n). This analysis was corroborated by X‐ray structural investigations of the products. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Mono‐ and Dimetallic Cyano Complexes with {Mo(η3‐allyl)(CO)2(N−N)} Fragments
Authors: Pérez Julio , Hevia Eva , Riera Lucía , Riera Víctor , García‐Granda Santiago , García‐Rodríguez Esther , Miguel Daniel
Published: March 2003

Treatment of [MoCl(η3‐allyl)(CO)2(phen)] with NaCN in CH2Cl2/MeOH afforded [Mo(CN)(η3‐allyl)(CO)2(phen)] [allyl = C3H5 (1a); 2‐MeC3H4 (1b)] as the sole products (no products of cyanide attack on the allyl group were detected). Treatment of 1a,b with [Mo(OTf)(η3‐C3H5)(CO)2(phen)] and NaBAr′4 in CH2Cl2 yielded the compounds [{Mo(η3allyl)(CO)2(phen)}(μ‐CN){Mo(η3‐C3H5)(CO)2(phen)}]BAr′4 (2a,b). Analogous treatment of 1a with fac‐[M(OTf)(CO)3(bipy)] (M = Mn, Re) and NaBAr′4 resulted in the synthesis of [{Mo(η3‐C3H5)(CO)2(phen)}(μ‐CN){M(CO)3(bipy)}]BAr′4 (3, 4), in which the C and N atoms of the cyano bridge are bonded to Mo and M (M = Mn, Re), respectively. The linkage isomer of 4 (C and N atoms of the cyano group bonded to Re and Mo, respectively) (6) was prepared by treatment of [Re(CN)(CO)3(bipy)] (5) with [Mo(OTf)(η3‐C3H5)(CO)2(phen)] and NaBAr′4. Compounds 1a, 2b, 3, and 6 were characterized by X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Charge‐Transfer Mechanisms between Gold Clusters
Authors: Torma Viktoria , Vidoni Olivia , Simon Ulrich , Schmid Günter
Published: March 2003

Electron‐transfer processes in complex chemistry are usually described by Taube’s “outer sphere” and “inner sphere” mechanisms. A behaviour related to these electron‐transfer mechanisms in complex chemistry can be observed for charge‐transfer transport between ligand protected Au55 nanoclusters. A linear dependence between cluster‐cluster distance and activation energy for electron transfer is observed if a noncovalent linkage exists; this interaction is independent of the distance in covalently linked clusters. Instead, the activation energy depends on the electronic nature of the linking molecules. The dithiols 1,5‐dithionaphthaline (1), 4,4′‐thiobis(benzenethiol) (2), and 2,8‐dithio‐6‐hydroxypurine (3) have been used as bifunctional covalent linkers either in their monomeric form (2) or, in the presence of air, dimerized via S−S bonds (1, 2, 3), causing an increase in the distance between the clusters and leading to the cluster networks 4−7. Noncovalent cluster networks are formed either by pellets of clusters with monodentate ligands in 8 and 11, linked only by van der Waals forces, or by using bifunctional spacers that interact with the clusters by ion attractions (9, 10). A study of the activation energies clearly indicates that in the case of noncovalently organized nanoparticles only the cluster spacing is of relevance, even if conjugated π‐systems like in 10 are used. This behaviour corresponds to an outer‐sphere mechanism. On the contrary, for covalently linked clusters the distances between them does not play a visible role. The activation energies all lie below those of the noncovalent examples, and a relation between cluster‐cluster distance and activation energy is not obvious. In those cases the relationship suggests an inner‐sphere mechanism where the transport properties of the spacer play a decisive role. These findings possibly help to explain contradictory reports on the conductivity behaviour of organic molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Monohelical Complexes of a Novel Asymmetric N4 Schiff Base: Unfamiliar Tetrahedral Environments of Manganese(II) and Iron(II) Helicates
Authors: Vázquez Miguel , Bermejo Manuel R. , Fondo Matilde , García‐Deibe Ana M. , Sanmartín Jesús , Pedrido Rosa , Sorace Lorenzo , Gatteschi Dante
Published: March 2003

The electrochemical reaction of the bis‐bidentate H2ABATs Schiff base [H2ABATs = N,N′‐bis(2‐tosylaminobenzylidene)‐2‐aminobenzylamine] with manganese, iron, cobalt, nickel, copper, zinc and cadmium was investigated. The reaction cell yields products of empirical formula M(ABATs). X‐ray diffraction studies show that [Mn(ABATs)]·0.75H2O (1), [Fe(ABATs)]·0.75H2O (2), [Ni(ABATs)]·0.75H2O (3), [Cu(ABATs)]·0.5H2O (4) and [Zn(ABATs)]·0.75H2O (5) are mononuclear distorted tetrahedral helical complexes in the solid state. Complexes 1 and 2 confirm the ability of this type of ligand to dictate the geometry around the metal centre, as is shown by the unfamiliar tetrahedral environments of manganese(II) and iron(II) ions in complexation with the Schiff bases. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Mono‐ and Bis‐Guanosine Adducts of Platinum Complexes with Carrier Ligands Having In‐Plane Steric Bulk: The Case of 1,10‐Phenanthroline and 2,9‐Dimethyl‐1,10‐phenanthroline
Authors: Margiotta Nicola , Papadia Paride , Fanizzi Francesco P. , Natile Giovanni
Published: March 2003

The steric hindrance generated by carrier ligands, in particular incis‐PtA2G2adducts (A2= diamine,G= guanine derivative), has often been used to slow down rotation about the platinum‐guanine bonds, thus allowing the characterisation of different conformers and the analysis of the interactions that are involved in the stabilisation of cisplatin adducts with DNA. In a previous study concerning 1,10‐phenanthroline and 2,9‐dimethyl‐1,10‐phenanthroline (phen and Me2phen, respectively), the Me2phen ligand was reported to form an unusual bis‐guanosine derivative with atransdisposition of the nucleobases and monodentate Me2phen. The present investigation has demonstrated that phen and Me2phen, like other bidentate ligands, allow formation of both mono‐ and bis‐guanosine derivatives, the latter having the usualcisconfiguration. In both the phen and Me2phen carrier ligands the rigidity of the phenanthroline skeleton is able to hinder rotation of the guanosine base(s) about the Pt−N(7) bond(s) and render the interconversion between rotamers slow on the NMR timescale even at 350 K (the highest temperature explored). However there are noticeable differences between the two ligands. As a consequence of the increased in‐plane steric bulk of Me2phen: (i) the H(8) chemical shifts within theHH(Head‐to‐Head) conformer and between theHT(Head‐to‐Tail) conformers become closer, (ii) the average H(8) chemical shift of theHTconformers is at higher field and that of theHHform at lower field, and (iii) theHTrotamers become even more favoured than theHHrotamer. Observation (ii) is in agreement with theHTrotamers preferring the “6‐in” conformation, which brings the six‐membered rings of the guanines closer to one another and is also in agreement with the phen ligand allowing a greater canting of the guanine bases than Me2phen. Moreover, free chloride ion readily displaces the coordinated guanosines, particularly in solvents of lower dielectric constants than water. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structural Variations and Formation Constants of First‐Row Transition Metal Complexes of Biologically Active Aroylhydrazones
Authors: Armstrong Claire M. , Bernhardt Paul V. , Chin Piao , Richardson Des R.
Published: March 2003

Iron chelators of the 2‐pyridinecarbaldehyde isonicotinoylhydrazone (HPCIH) class show high potential for the treatment of iron overload diseases. In the present study, selected first‐row transition metal (from Mn to Zn) complexes with HPCIH and 2‐pyridinecarbaldehyde (4′‐aminobenzoyl)hydrazone (HPCAH) were synthesised and characterised. Crystallography reveals that HPCAH exclusively forms bis complexes with divalent transition metals, with each ligand coordinating meridionally through its pyridine‐N, imine‐N and carbonyl‐O atoms, forming distorted octahedral cis‐MN4O2 complexes. Complexes of HPCIH were more varied and unpredictable, with metal/ligand ratios of 1:1, 1:2, 2:2 and 3:2 obtained with different metal ions. The isonicotinoyl ring N‐atom in HPCIH was found to be an effective ligand, and this resulted in the varied metal/ligand ratios observed. The formation constants of divalent metal complexes with HPCIH were determined by potentiometric titrations and the values obtained were consistent with similar tridentate ligands and with the Irving−Williams order. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
New Rhenium(I) and Rhenium(II) Species Assembled by Stereospecific Azopyridine Chelation
Authors: Sengupta Suman , Chakraborty Indranil , Chakravorty Animesh
Published: March 2003

The spontaneous reaction of [ReO(OEt)I2(PPh3)2] with 2,2′‐azobipyridine (L) in acetonitrile, and of [ReOCl3(PPh3)2] with L in toluene, proceeds stereospecifically furnishing the green tris‐chelate [ReIL3]I (1) and the red bis‐chelate [ReIICl2L2] (2), respectively. A structure determination reveals that the coordination geometry of 1 is facial and that of 2 is cis(Cl,Cl)‐trans(Np,Np)‐cis(Na,Na) (Np is a pyridine nitrogen and Na is an azo nitrogen). The isomer preference is exclusive in both cases and no other isomer has been observed. The average N−N distance in both compounds is about 1.35 Å, signifying the presence of strong d(Re)‐π*(azo) back‐bonding which plays a crucial role in controlling isomer specificity. The bis‐chelate 2 is a one‐electron paramagnet and displays a six‐line EPR spectrum in fluid solution with g = 2.080 and A = 320 G. The 1H NMR spectrum of diamagnetic 1 is consistent with the facial geometry. In acetonitrile solution 1 displays an ReII/ReI couple and 2 an ReIII/ReII couple, the reduction potentials being 0.60 and 0.50V vs. SCE respectively. The violet‐coloured imide complex [ReVCl3(NC6H4Cl‐p)L] (3) is also reported; it displays an ReVI/ReV redox wave at 1.33 V vs. SCE. The stabilization of the lower rhenium oxidation states in 1 and 2 is consistent with the decrease of metal reduction potential with progressive L chelation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
[Bis(oxazolinyl)pyrrole]palladium Complexes as Catalysts in Heck‐ and Suzuki‐Type C−C Coupling Reactions
Authors: Mazet Clément , Gade Lutz H.
Published: March 2003

The two bis(oxazoline)pyrrole ligand precursors 2,5‐bis(4,4′‐dimethyl‐4,5‐dihydrooxazol‐2‐yl)pyrrole (“dmoxpH”, 2) and 2,5‐bis(4,4′‐dimethyl‐4,5‐dihydrooxazol‐2‐yl)‐3,4‐diethylpyrrole (“Et2dmoxpH”, 5) have been synthesised and metallated by treatment with n‐butyllithium at −78 °C in diethyl ether. Treatment of the lithium pyrrolide with 1.1 mol‐equiv. of [PdCl2(COD)] gave the corresponding helical dinuclear palladium complexes [Pd2Cl2(dmoxp)2] (6) and [Pd2Cl2(Et2dmoxp)2] (7). In both complexes the tridentate bis(oxazolinyl)pyrrolide ligands bridge the two metal centres, with one of the oxazoline rings and the charged pyrrolide being coordinated to the one Pd centre while the second oxazoline ring is twisted relative to the pyrrolide unit and coordinates to the second palladium atom. Complexes 6 and 7 were found to be precursors for active catalysts for Heck coupling reactions of styrene and ethyl acrylate, with turnover numbers of over 9000 for the former, as well as for disubstituted alkenes such as methyl crotonate and methyl cinnamate. Complex 6 was found to be a very active catalyst for Suzuki coupling reactions of activated and deactivated bromoarenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture
Authors: Olenev Andrei V. , Baranov Alexei I. , Oleneva Olga S. , Vorontsov Ivan I. , Antipin Mikhail Yu. , Shevelkov Andrei V.
Published: March 2003

The cover picture shows the arrangement of the 3‐D [Hg7As4]4+ host framework and the AgI32− guest anions in a novel supramolecular architecture [Hg7As4](AgI3)2, self‐assembled from a heterogeneous system at high temperature. Although the host−guest interaction is weak, it governs both the geometry of the host framework (mercury atoms, blue; arsenic atoms, pink) and guest anions (silver atoms, red; iodine atoms, violet) and the positioning of the guest in the framework cavities. A mutual adjustment of the host and guests results is the unusual off‐plane geometry of the AgI32− anion. Details are discussed in the article of A. V. Shevelkov et al. on p. 1053 ff.
The Synthesis and Structure of P−C−P Bridged Ferrocene
Authors: Shevchenko Igor , Shakhnin Dmitrii , Zhang Hongming , Lattman Michael , Röschenthaler Gerd‐Volker
Published: March 2003

The reaction of dilithioferrocene 12 with methylene‐bis(dialkylaminochlorophosphanes) 13a,b (a = CH3, b = C2H5) leads to the formation of compounds 14a,b in which the two cyclopentadiene rings are bridged by a P−C−P chain. Because of the cyclic structure, cis‐ and trans‐isomerism is expected. The cis‐ and trans‐isomers of the sulfur derivative 16b have been separated by column chromatography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Hydrothermal Synthesis and Characterisation of Two Novel Large‐Pore Framework Vanadium Silicates
Authors: Brandão Paula , Valente Anabela , Philippou Andreas , Ferreira Artur , Anderson Michael W. , Rocha João
Published: March 2003

Two new large‐pore sodium vanadium silicates, denoted AM‐15 and AM‐17 (Aveiro‐Manchester, structures number 15 and 17) with framework composition Na6Si14V4O39 and Na4CaSi10V2O27, respectively, are reported. Electron paramagnetic resonance (EPR), Fourier transform infrared (FTIR) and diffuse reflectance ultraviolet‐visible (DR UV/Vis) spectroscopy reveal that as‐prepared AM‐15 contains both VIV and VV in a square pyramidal and tetrahedral coordination, respectively, while AM‐17 contains predominantly octahedral VIV. The thermal stability of AM‐15 in air is modest (ca. 380 °C), while AM‐17 is stable up to 450 °C. The acid‐base and redox properties of AM‐17 have been assessed by the conversion of isopropanol and ethanol oxidation, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure and Characterization of Two New Complexes [Cu2(C3H2O4)2(C4H4N2)]·2H2O and [Zn2(OH2)2(C3H2O4)2(C4H4N2)]
Authors: Zhang Xiutang , Lu Canzhong , Zhang Quanzheng , Lu Shaofang , Yang Wenbin , Liu Jiacheng , Zhuang Honghui
Published: March 2003

Two new complexes with three‐dimensional extended frameworks linked by pyrazine and malonate ligands, namely [Cu2(C3H2O4)2(C4H4N2)]·2H2O and [Zn2(OH2)2(C3H2O4)2(C4H4N2)], have been prepared and characterized by X‐ray crystallography, IR, EPR and UV/Vis spectroscopy, their magnetic properties and electrical conductivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Solid‐State Adducts between C60 and Decamethylferrocene
Authors: Arrais Aldo , Diana Eliano , Gobetto Roberto , Milanesio Marco , Viterbo Davide , Stanghellini Pier Luigi
Published: March 2003

Co‐deposition from concentrated solutions of C60 and Fe[C5(CH3)5]2 affords two solid products in different yields. The major product 1, in the form of regular shaped crystals, has been investigated by X‐ray diffraction, 13C CPMAS NMR and vibrational spectroscopy, which showed it to be a co‐crystalline adduct of C60 and Fe[C5(CH3)5]2 with no significant electron charge transfer between the two building blocks. The minor product 2, in the form of an amorphous powder, has been investigated by vibrational techniques. Both IR and Raman spectra are consistent with a solid structure in which electron transfer between the two units appears to be possible. ((© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure, and Characterization of [RAl(μ‐NHEt)(μ‐NEt)2Si(NHEt)]2 (R = Me, Et)
Authors: Kaskel Stefan , Lehmann Christian W. , Chaplais Gerald , Schlichte Klaus , Khanna Meik
Published: March 2003

The reaction between tetrakis(ethylamino)silane, Si(NHEt)4 (1) and trialkylaluminium compounds AlR3 [R = Me (2), R = Et (3)] results in partial deprotonation of 1 and subsequent formation of a new dimeric alumosilazane in high yield. Single‐crystal X‐ray analyses reveal the structure of two new four‐membered ring compounds [RAl(μ‐NHEt)(μ‐NEt)2Si(NHEt)]2 [R = Me (4), R = Et (5)]. They are isostructural and crystallize in the triclinic space group P$\bar 1$
(No. 2) with a = 8.3052(8) Å, b = 9.8323(9) Å, c = 10.324(1) Å, α = 115.498(4)°, β = 97.684(4)°, γ = 94.382(4)° (4) and a = 8.2319(3) Å, b = 9.3748(5) Å, c = 10.8221(6) Å, α = 107.035(2)°, β = 104.435(2)°, γ = 94.375(2)° (5). The alternating edge‐ and corner‐sharing SiN4‐ and AlCN3‐tetrahedra represent a new structural motif with μ‐NHEt and μ‐NEt groups in one double bridge. The compounds were further characterized by elemental analysis, mass spectrometry, and NMR and IR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structure and Reactivity Studies on Dinuclear Copper Complexes of the Ligand α,α′‐Bis{bis[1‐(1′‐methyl‐2′‐benzimidazolyl)methyl]amino}‐m‐xylene
Authors: Battaini Giuseppe , Casella Luigi , Gullotti Michele , Monzani Enrico , Nardin Giorgio , Perotti Angelo , Randaccio Lucio , Santagostini Laura , Heinemann Frank W. , Schindler Siegfried
Published: March 2003

The ligand α,α′‐bis{bis[1‐(1′‐methyl‐2′‐benzimidazolyl)methyl]amino}‐m‐xylene (L‐55) forms the complexes [CuI2(L‐55)(MeCN)2](PF6)2 (1) and [CuII2(L‐55)(OMe)2][ClO4]2 (2), in which an extremely weak axial amine interaction is imposed by the small five‐membered benzimidazole chelating ring units. This structural feature has been characterized by X‐ray crystal structure determination. In 1, the CuI centers are three‐coordinate with ligation from two benzimidazolyl and one acetonitrile N‐donors, in a slightly distorted trigonal arrangement. In 2, each CuII center has a distorted square‐planar geometry and coordinates to the benzimidazolyl N atoms and the bridging methoxy groups in the basal positions, with a much weaker interaction with the tertiary amine N in an apical position. These structural features affect the reactivities of the copper(I)− and copper(II)−L‐55 complexes toward dioxygen and hydrogen peroxide, respectively. [CuI2(L‐55)(MeCN)2]2+ does not produce a stable peroxo complex, but undergoes an irreversible oxidation to copper(II) species, while [CuII2(L‐55)(H2O)2]4+ reacts slowly with hydrogen peroxide to undergo regiospecific hydroxylation of the ligand at one benzylic carbon atom, which causes decomposition of the complex. [Cu2(L‐55)(H2O)2]4+ is easily converted into its bis(μ‐hydroxo) adduct [Cu2(L‐55)(OH)2]2+. This pH‐driven equilibrium was monitored by paramagnetic 1H NMR spectroscopy, and the solution magnetic properties of the complexes were determined by the Evans susceptibility method. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Novel Adducts of the Anticancer Drug Oxaliplatin with Glutathione and Redox Reactions with Glutathione Disulfide
Authors: Fakih Sarah , Munk Vivienne P. , Shipman Michelle A. , Murdoch Piedad del Socorro , Parkinson John A. , Sadler Peter J.
Published: March 2003

Reactions of [Pt(rac‐1,2‐DACH)Cl2], [Pt(1R,2R‐DACH)Cl2] and the anticancer drug oxaliplatin with the tripeptide glutathione and glutathione disulfide have been studied by HPLC, ESI‐MS and NMR methods. The same two major products are formed in each reaction: a thiolate‐bridged dimer and a novel thiolate‐bridged dinuclear macrochelate containing a nine‐membered chelate ring. Redox reactions of PtII anticancer drugs with biological disulfides are of potential importance to their mechanism of action. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Reactivity, Crystal Structures and Catalytic Activity of New Chelating Bisimidazolium‐Carbene Complexes of Rh
Authors: Poyatos Macarena , Mas‐Marzá Elena , Mata José A. , Sanaú Mercedes , Peris Eduardo
Published: March 2003

A series of new bridging, chelating and pincer N‐heterocyclic carbenes of RhI and RhIII have been obtained under mild conditions. The compounds have been fully characterised and their crystal structures determined. The chelate‐pincer coordination of the ligands means that the stability of these compounds is significantly greater than other carbene complexes of Rh. The compounds have been tested in catalytic reactions such as hydrogen transfer from alcohols to ketones, and hydrosilylation of terminal olefins and alkynes; they show a high activity for both processes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Crystal Structure of Bis[acetone‐1‐naphthoylhydrazinato(−1)]copper(II) and Investigations of Intermolecular Interactions
Authors: Tomić Zoran D. , Leovac Vukadin M. , Pokorni Srdjan V. , Zobel Dieter , Zarić Snežana D.
Published: March 2003

In the crystal structure of the bis(acetone‐1‐naphthoylhydrazinato)copper(II) complex there are interactions of neighbouring molecules via naphthyl groups; the naphthyl group of one molecule interacts with the copper centre and CH3group of another molecule. The geometry of the crystal structure and dispositions of charges in the naphthyl and chelate rings indicate that there are stacking interactions between the aromatic ring and, not only the copper atom, but also the whole chelate ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The First Structurally Characterized Trinuclear Dipicolinato Manganese Complex and its Conversion into a Mononuclear Species by Ligand Substitution
Authors: Ma Chengbing , Chen Changneng , Liu Qiutian , Liao Daizheng , Li Licun
Published: March 2003

The novel complex [Mn3(pdc)3(bpy)3(H2O)2] (1) (H2pdc = 2,6‐pyridinedicarboxylic acid, also known as 2,6‐dipicolinic acid; bpy = 2,2′‐bipyridine), has been obtained from the reaction of polymeric [MnK2(pdc)2(H2O)7]n (2) with bpy, and is the first example of a structurally characterized, trinuclear Mn complex incorporating dipicolinato ligands. All the MnII centers are seven‐coordinate in severely distorted pentagonal‐bipyramidal geometries. The conversion of 1 to mononuclear [Mn(pdc)(bpy)(Him)2] (3) (Him = imidazole), which is the first seven‐coordinate Mn complex with a Him ligand, has also been achieved by substitution of the labile ligand in 1 by Him. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Coordination Chemistry of Nitrile and Amino Pendant Arm Derivatives of [9]aneN2S and [9]aneNS2 with PdII and CuII
Authors: Arca Massimiliano , Blake Alexander J. , Lippolis Vito , Montesu Daniela R. , McMaster Jonathan , Tei Lorenzo , Schröder Martin
Published: March 2003

Palladium(II) and copper(II) complexes [Pd(L1)Cl2], [Pd(L3)Cl2], [Cu(L1)Cl2], [Cu(L3)Cl2], [Pd(L2)][BF4]2, [Pd(L4)Cl]BF4, [Cu(L2)][NO3]2 and [Cu(L4)Cl]PF6 of the nitrile (L1 and L3) and amino (L2 and L4) pendant arm derivatives of 1‐thia‐4,7‐diazacyclononane ([9]aneN2S) and 7‐aza‐1,4‐dithiacyclononane ([9]aneNS2) have been prepared and fully characterised. In each case, a square‐pyramidal coordination sphere is observed at both metal ions with either one or two Cl− anions completing the donor set. The tridentate nine‐membered macrocyclic moiety adopts a [333] conformation in all the complexes obtained. The five‐membered chelate rings involving the donor atoms of the basal plane adopt a gauche configuration with very similar degrees of puckering. The “innocent” nitrile pendant arms in L1 and L3 do not bind to the metal ions, but still appear to influence the binding of the tridentate macrocyclic frameworks via the tertiary amine sites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Intercalation of Poly(Ethylene Oxide) Derivatives into Layered Double Hydroxides
Authors: Leroux Fabrice , Aranda Pilar , Besse Jean‐Pierre , Ruiz‐Hitzky Eduardo
Published: March 2003

Mono‐ and bi‐functional guest molecules, poly(ethylene glycol)‐n‐alkyl‐3‐sulfopropyl diether (PEG‐AS) and poly(ethylene glycol)dicarboxylic acid (PEG‐DC), containing hydrophilic polyoxyethylene (PEO) chains of different ethylene oxide units (EOUs) are incorporated between the layers of Cu2Cr(OH)6Cl·nH2O hydrotalcite‐type materials. The intercalation compounds are characterized by chemical analysis, adsorption measurements, XRD, SEM, FTIR and 13C CP‐MAS spectroscopy. It is found that the polyoxyethylene chain of PEG‐DC distorts its helical symmetry when it is intercalated in the LDH galleries. The basal spacing of PEG‐AS nanocomposites is independent of the number, n, of EOUs in the polymer chain. In addition to changes in the IR bands, 13C CP‐MAS spectra are modified with new resonance peaks at more deshielded values. These facts suggest a strong interaction of polyether chains with the LDH inner‐surface, with the hydrophobic alkyl tail dangling into the interlamellar space. It is shown that the terminal functionalities dictate the arrangement of the PEO chains. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis of Tetrahemispheraplexes with Ammonium, Alkylammonium or Alkaline Metal Ions as Exohedral Guests via Self‐Assembly or Guest Exchange
Authors: Saalfrank Rolf W. , Demleitner Bernhard , Glaser Horst , Maid Harald , Reihs Stefan , Bauer Walter , Maluenga Monica , Hampel Frank , Teichert Markus , Krautscheid Harald
Published: March 2003

To study the interplay between the steric demand of the guest and the space available at the host, we have prepared the tetraammonium complexes {(NH4)4∩[Mg4(L1/2)6]} 1, tetrakis(methylammonium) complexes {(Me‐NH3)4∩[Mg4(L1/2)6]} 2, tetrakis(ethylammonium) complex {(Et‐NH3)4∩[Mg4(L1)6]} 3, and mixed sodium tris(ethylammonium) complex {Na(Et‐NH3)3∩[Mg4(L2)6]} 4. The tetrahemispheraplexes 1−4 were available in one‐pot syntheses. The tetrakis(alkylammonium) clusters {(R1−NH3)4∩[Mg4(L1)6]} 5 and the mixed diammonium‐bis(p‐methoxybenzylammonium) cluster {(NH4)2(R2−NH3)2∩[Mg4(L1)6]} 6, however, were prepared by exchange of the ammonium ions of 1a by alkylammonium ions. Similarly, exchange of the four ammonium ions of 1b by alkaline metal cations afforded the tetraalkaline metal tetrahemispheraplexes {M4∩[Mg4(L2)6]} 7.
Electrochemical Biosensors for Detection of Biological Warfare Agents
Authors: Shah Jasmin , Wilkins Ebtisam
Published: March 2003

This review discusses current development in electrochemical biosensors for detection of biological warfare agents. This could include bacteria, viruses and toxins that are aerosoled deliberately in air, food or water to spread terrorism and cause disease or death to humans, animals or plants. The rapid and unequivocal detection and identification of biological warfare agents is a major challenge for any government including military, health and other government agents. Reliable, specific characterization and identification of the microorganism from sampling location, either air, water, soil or others is required. This review will survey different types of electrochemical biosensors has been developed based on the following: i) Immunosensors ii) PCR (DNA base Sensor) iii) Bacteria or whole cell sensor and iv) Enzyme sensor. This article gives an overview of electrochemical biosensor for detection of biological warfare agents. Electrochemical biosensors have the advantages of sensitivity, selectivity, to operate in turbid media, and amenable to miniaturization. Recent developments in immunofiltration, flow injection, and flow‐through electrochemical biosensors for bacteria, viruses, and toxin detection are reviewed. The current research and development in biosensors for biological warfare agents detection is of interest to the public as well as to the defense is also discussed.
Nanodiamond Thin Film Electrodes: Metal Electro‐Deposition and Stripping Processes
Authors: Chi Hian Lau , Grehan Kieron J. , Goeting Christiaan H. , Compton Richard G. , Foord John S. , Marken Frank
Published: March 2003

The properties of a nanodiamond thin film deposit formed on titanium substrates in a microwave‐plasma enhanced CVD process, are investigated for applications in electroanalysis. The nanodiamond deposit consists of intergrown nano‐sized platelets of diamond with a high sp2 carbon content giving it high electrical conductivity and electrochemical reactivity. Nanodiamond thin film electrodes (of approximately 2 μm thickness) are characterized by electron microscopy and electrochemical methods. First, for a reversible one electron redox system, Ru(NH3)63+/2+, nanodiamond is shown to give well‐defined diffusion controlled voltammetric responses. Next, metal deposition processes are shown to proceed on nanodiamond with high reversibility and high efficiency compared to processes reported on boron‐doped diamond. The nucleation of gold is shown to be facile at edge sites, which are abundant on the nanodiamond surface. For the deposition and stripping of both gold and copper, a stripping efficiency (the ratio of electro‐dissolution charge to electro‐deposition charge) of close to unity is detected even at low concentrations of analyte. The effect of thermal annealing in air is shown to drastically modify the electrode characteristics probably due to interfacial oxidation, loss of active sp2 sites, and loss of conductivity.
Investigation of the Effect of Different Glassy Carbon Materials on the Performance of Prussian Blue Based Sensors for Hydrogen Peroxide
Authors: Ricci Francesco , Palleschi Giuseppe , Yigzaw Yirgalem , Gorton Lo , Ruzgas Tautgirdas , Karyakin Arkady
Published: March 2003

Three different kinds of glassy carbon (GC‐R, GC‐K, GC‐G) were equally pretreated, further modified with electrochemically deposited Prussian Blue and used as sensors for hydrogen peroxide at an applied potential of −50 mV (vs. Ag|AgCl). Their performance was evaluated with respect to the following parameters: the coverage and electrochemistry of the electrodeposited Prussian Blue, the sensitivity and the lower limit of detection for hydrogen peroxide, and the operational stability of the sensors. GC‐R showed the best behavior concerning the surface coverage and the operational stability of the electrodeposited Prussian Blue. For this electrode the sensitivity for hydrogen peroxide (10 μM) was 0.25 A/M cm2 and the detection limit was 0.1 μM. Scanning electron microscopy was used to study the surfaces of the three electrodes before and after the electrodeposition of Prussian Blue and to search for the reason for the three different behaviors between the different glassy carbon materials. The Prussian Blue modified GC‐R was also used for the construction of a glucose biosensor based on immobilizing glucose oxidase in Nafion membranes on top of electrodeposited Prussian Blue layer. The operational stability of the glucose biosensors was studied in the flow injection mode at an applied potential of −50 mV (vs. Ag|AgCl) and alternatively injecting standard solutions of hydrogen peroxide (10 μM) and glucose (1 mM) for 3 h. For the GC‐R based biosensor a 2.8% decrease of the initial glucose response was observed.
Which Parameters Affect the Response of the Channel Biosensor?
Authors: Losic Dusan , Zhao Min , Shapter Joe G. , Gooding J. Justin
Published: March 2003

The important parameters in defining the response of the portable channel biosensor described previously are explored by connecting the portable flow cell to a gravity feed flow system and using a highly defined enzyme immobilization protocol which ensures the enzyme reaction is a surface reaction. The enzyme glucose oxidase (GOD) was immobilized by covalent attachment to a self‐assembled monolayer modified gold surface. As a glucose solution flowed down the rectangular duct defined by the flow cell, it passed over the enzyme layer where the enzyme reaction produced hydrogen peroxide. The hydrogen peroxide was swept further downstream to the detector electrode. The response of such an enzyme electrode was shown to be limited by mass transport of the cosubstrate oxygen to the enzyme layer. Increasing the amount of oxygen in the sample meant the response of the biosensor became limited by the enzyme kinetics. The influence of parameters such as flow rate, height of the channel, enzyme layer length and the gap between the enzyme layer and the detector electrode were explored.
Electrochemical Characterization of Poly(N‐acetylaniline)/Nafion Composite Film in Neutral and Basic Aqueous Solutions
Authors: Zheng Longzhen , Wu Shouguo , Lin Xiangqin , Shi Chunhua , Nie Lei , Rui Lei
Published: March 2003

Electrochemical synthesis of poly(N‐acetylaniline) (PNAANI)/Nafion composite film was carried out by cyclic voltammetry (CV). Its surface morphology, which was evaluated by scanning electron microscopy (SEM), revealed that PNAANI was dispersed into the Nafion film uniformly. X‐ray photoelectron spectrum (XPS) of the composite film was also examined. The electroactivity of the composite film was high in neutral and basic solutions, and the stability of PNAANI/Nafion film in neutral and basic solutions was excellent.