Surface modification and characterization of phenanthroline nanofilms on carbon substrate

Modification of glassy carbon (GC) surfaces with phenanthroline derivatives (PDs) such as 5‐amino‐1,10‐phenanthroline (5AP) and 5,6‐diamino‐1,10‐phenanthroline (56DAP) is described in this study. Surface modification experiments were performed by cyclic voltammetry (CV) scanning from + 1.2 to + 2.7 V at scan rate of 100 mV/s applying 30 potential scans in acetonitrile (CH₃CN) containing 1 mM PDs and 100 mM tetrabutylammoniumtetrafluoroborate (TBATFB). The presence of PDs on GC electrode was confirmed using CV, electrochemical impedance spectroscopy (EIS), contact angle measurements and ellipsometry and comparing with the results of bare GC electrode. A mechanism was proposed for the electrochemical modification of the GC electrode surface with PDs. The structure of the 5AP and 56DAP films was also discussed in the light of electrochemical and spectroscopic data. The complex‐forming ability of the modified surfaces against metal cations was investigated by square‐wave voltammetry (SWV). It was shown that surfaces having 1,10‐phenanthroline ligands with different functional groups were quite useful for the determination of transition metal ions. Copyright © 2010 John Wiley & Sons, Ltd.     

The electrochemical behavior of some podands at a benzo[c]cinnoline modified glassy carbon electrode

This paper describes the grafting of benzo[c]cinnoline (BCC) molecules on glassy carbon (GC) electrode surface. The attachment of BCC molecules to carbon substrate is induced by the electrochemical reduction of the corresponding diazonium salt. The modification of GC with BCC diazonium salt was done in aprotic solution and proved by blocking of dopamine electron transfer. The presence of BCC at the GC surface was characterized by cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). On modified surface, the electrochemical behavior of two different types of podands and the catalytic effects of the GC-BCC surface were studied. The XPS was used to monitor element characteristics of the adsorbates on the GC surface and confirm the attachment of BCC molecules to the GC surface.     

4,4,6,6‐Tetra­chloro‐2,2‐(ethyl­ene­di­oxy­di‐o‐phenyl­enedi­imino)‐2λ5,4λ5,6λ5‐cyclo­triphosphazene

The title ligand, C₁₄H₁₄Cl₄N₅O₂P₃, is a cyclo­phosphazene lariat (PNP pivot) ether with a spiro‐cyclic 11‐membered macrocyclic ring containing two ether O and two N atoms; the phosphazene ring is nearly planar. The macrocyclic ring contains a four‐centred (trifurcate) N—H⋯O/N—H⋯N hydrogen bond, and the relative inner‐hole size of the macrocycle is ∼1.14 Å in radius. The mol­ecules are linked about inversion centres by N—H⋯N hydrogen bonds into centrosymmetric dimers.     

Phosphorus‐nitrogen compounds. Part 39. Syntheses and Langmuir‐Blodgett thin films and antimicrobial activities of N/N and N/O spirocyclotriphosphazenes with monoferrocenyl pendant arm

The Cl substitution reactions of the N/N ( 1 ‐ 3 ) and N/O ( 4 and 5 ) spirocyclic monoferrocenylphosphazenes with 1,4‐dioxa‐8‐azaspiro[4,5]decane (DASD) produce the mono‐ ( 1a ‐ 5a ), geminal‐ ( 1b ‐ 5b ) and tetrakis‐DASD‐substituted ferrocenylspirocyclotriphosphazenes ( 1c ‐ 5c ). The mono‐ and geminal‐DASD‐substituted phosphazenes have two and one stereogenic P‐centers, respectively. The structures of the compounds were established by spectroscopic techniques. The molecular structures of 3a and 2b were evaluated using X‐ray crystallography. Additionally, the ultrathin and highly ordered Langmuir‐Blodgett (LB) films of 3a and 2b were also prepared. The characterizations of the LB films were done using p‐polarized grazing angle (GAIR) and horizontal attenuated total reflectance (HATR) techniques. On the other hand, the antimicrobial activities of the eight phosphazene derivatives against G(+) and G(‐) bacteria and fungi were investigated. Furthermore, the interactions between the compounds and plasmid DNA were studied by agarose gel electrophoresis.     

Linkages between international stock markets: A multivariate long-memory approach

This paper aims to analyze the linkages between international stock markets and to search for an optimum model for analyzing their interactions taking into consideration their geographical location, using the vector fractionally integrated autoregressive moving-average (VARFIMA) model. This model has not so far been employed in examining the interdependence among the stock markets of Germany, Japan, the UK, and the USA. The results of the paper show that there is an interconnection among the stock markets of these countries.     

Phosphorus–nitrogen compounds. Part VI. Aminolysis of octachlorocyclotetraphosphazatetraene and the crystal structure of 2-trans-6-bis(n-propylamino)-2,4,4,6,8,8-hexakis-tert-butylaminocyclo-2λ, 4λ, 6λ, 8λ-tetraphosphazatetraene

The reactions of 2-trans-6-N₄P₄(NHPrⁿ)₂Cl₆ (2), which was obtained from N₄P₄Cl₈ (1) and n-propylamine, with pyrrolidine and t-butylamine in different solvents have been studied. Compound (2) gave two different products, namely monocyclic (3 and 5) and bicyclic (4 and 6) phosphazenes. Compounds (2–6) have been characterized by elemental analysis, IR, ¹H-, ¹³C-, ³¹P NMR, HETCOR and MS and the structure of compound (5) has been examined crystallographically. The bicyclic phosphazene (6) is the first exciting example of bicyclic phosphazenes containing chlorine atoms, in the literature. The formation mechanisms of bicyclic phosphazenes are re-considered by taking into account the synthesis of compound (6), which contains three stereogenic phosphorus atoms. Compound (5) crystallizes in the monocyclic space group P2₁/n with a=13.974(2), b=17.836(5), and c=18.683(4) Å, β=98.50(1)°, V=4605.4(2) Å³, Z=4 and D_x=1.051 g cm^−3. It consists of a non-centrosymmetric, non-planar phosphazene ring in a saddle conformation, with two n-propylamino (in 2-trans-6 positions) and six bulky t-butylamino side groups. The bulky substituents are instrumental in determining the molecular geometry.     

Phosphorus-Nitrogen Compounds: Part 25. Syntheses,Spectroscopic, Structural and Electrochemical Investigations,Antimicrobial Activities,and DNA Interactions of Ferrocenyldiaminocyclotriphosphazenes

Abstract

The condensation reactions of hexachlorocyclotriphosphazene (N₃P₃Cl₆) with mono (1 and 2) and bisferrocenyldiamines (3–5 and 7) resulted in the formation of tetrachloro mono- (8 and 9) and bisferrocenylspirocyclotriphosphazenes (10–13). In addition the tetramorpholino mono- (8a and 9a) and bisferrocenylphosphazenes (10a–12a) were obtained from the reactions of the corresponding tetrachlorophosphazenes (8–12) with excess morpholine. The structures of all the phosphazenes were determined using FTIR, MS, ¹H, ¹³C, and ³¹P NMR and 2-dimensional NMR techniques. The structures of 9a and 13 were determined by single crystal X-ray diffraction techniques. Cyclic voltammetric investigations of compounds 8a, 9a, and 11a revealed that ferrocene redox centers undergo reversible oxidation. These ferrocenylphosphazenes appear to be quite robust electrochemically. Interactions between the compounds 8a, 9a, 11a, and 12a and pBR322 plasmid DNA were investigated by agarose gel electrophoresis.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures.]     

Biofuel Cell Based on Anode and Cathode Modified by Glucose Oxidase

A single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel glucose is reported. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose consuming biocatalyst for both anode and cathode of the BFC. The 5‐amino‐1,10‐phenanthroline modified graphite rod electrode (GRE) with cross‐linked GOx was used as the bioanode, and the GRE with co‐immobilised horseradish peroxidase and GOx was exploited as the biocathode of the BFC. The open‐circuit voltage of the designed BFC exceeded 450 mV and a maximal power density of 3.5 µW/cm² was registered at a cell voltage of 300 mV.