Pseudomonas aeruginosa PumA acts on an endogenous phenazine to promote self-resistance.

The activities of critical metabolic and regulatory proteins can be altered by exposure to natural or synthetic redox-cycling compounds. Many bacteria, therefore, possess mechanisms to transport or transform these small molecules. The opportunistic pathogen Pseudomonas aeruginosa PA14 synthesizes phenazines, redox-active antibiotics that are toxic to other organisms but have beneficial effects for their producer.

Three-coordinate late transition metal fluorinated alkoxide complexes.

Homoleptic fluorinated alkoxide complexes have been prepared from KOC4F9, 1, via salt metathesis routes. One four-coordinate K{K(18C6)}[Co(OC4F9)4], 2, and four three-coordinate complexes: {K(18C6)}[Fe(OC4F9)3], 3, {K(18C6)}[Co(OC4F9)3], 4, {K(18C6)}[Cu(OC4F9)3], 5, and {K(18C6)}[Zn(OC4F9)3], 6, have been prepared and all except 5 have been characterized crystallographically. Compounds 3, 4, and 6 are very rare examples of monomeric, trigonal alkoxide complexes.

DNA-mediated electrochemistry.

The base pair stack of DNA has been demonstrated as a medium for long-range charge transport chemistry both in solution and at DNA-modified surfaces. This chemistry is exquisitely sensitive to structural perturbations in the base pair stack as occur with lesions, single base mismatches, and protein binding. We have exploited this sensitivity for the development of reliable electrochemical assays based on DNA charge transport at self-assembled DNA monolayers.

Determination of ammonia based on the electro-oxidation of hydroquinone in dimethylformamide or in the room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

The results detail a novel methodology for the electrochemical determination of ammonia based on its interaction with hydroquinone in DMF. It has been shown that ammonia reversibly removes protons from the hydroquinone molecules, thus facilitating the oxidative process with the emergence of a new wave at less positive potentials. The analytical utility of the proposed methodology has been examined with a linear range from 10 to 95ppm and corresponding limit-of-detection of 4.

Redmond Red as a redox probe for the DNA-mediated detection of abasic sites.

Redmond Red, a fluoropore containing a redox-active phenoxazine core, has been explored as a new electrochemical probe for the detection of abasic sites in double-stranded DNA. The electrochemical behavior of Redmond Red-modified DNA at gold surfaces exhibits stable, quasi-reversible voltammetry with a midpoint potential centered around -50 mV versus NHE. Importantly, with Redmond Red positioned opposite an abasic site within the DNA duplex, the electrochemical response is significantly enhanced compared to Redmond Red positioned across from a base.

Extended electrochemical windows made accessible by room temperature ionic liquid/organic solvent electrolyte systems.

The electrochemical windows of acetonitrile solutions doped with 0.1 M concentrations of several ionic liquids were examined by cyclic voltammetry at gold and platinum microelectrodes. These results were compared with those observed in the commonly used 0.

Homoleptic cobalt and copper phenolate A2[M(OAr)4] compounds: the effect of phenoxide fluorination.

Two series of homoleptic phenolate complexes with fluorinated aryloxide ligands A2[M(OAr)4] with M=Co2+ or Cu2+, OAr-=(OC6F5)- (OArF) or [3,5-OC6H3(CF3)2]- (OAr'), A+=K (18-crown-6)+, Tl+, Ph4P+, Et3HN+, or Me4N+ have been synthesized. Two related complexes with nonfluorinated phenoxide ligands have been synthesized and studied in comparison to the fluorinated aryloxides demonstrating the dramatic structural changes effected by modification of OPh to OAr(F). The compounds [K(18-crown-6)]2[Cu(OArF)4], 1a; [K(18-crown-6)]2[Cu(OAr')4], 1b; [Tl2Cu(OArF)4], 2a; [Tl2Cu(OAr')4], 2b; (Ph4P)2[Cu(OArF)4], 3; (nBu4N)2[Cu(OArF)4], 4; (HEt3N)2[Cu(OArF)4], 5; [K(18-crown-6)]2[Cu2(mu2-OC6H5)2(OC6H5)4], 6; [K(18-crown-6)]2[Co(OArF)4], 7a; [(18-crown-6)]2[Co(OAr')4], 7b; [Tl2Co(OArF)4], 8a; [Tl2Co(OAr')4], 8b; (Me4N)2[Co(OArF)4], 9; [Cp2Co]2[Co(OAr')4], 10; and [(18-crown-6)])[Co2(mu2-OC6H5)2(OC6H5)4], 11, have been characterized with UV-vis and multinuclear NMR spectroscopy and solution magnetic moment studies.

Non-haloaluminate room-temperature ionic liquids in electrochemistry--a review.

Some twenty-five years after they first came to prominence as alternative electrochemical solvents, room temperature ionic liquids (RTILs) are currently being employed across an increasingly wide range of chemical fields. This review examines the current state of ionic liquid-based electrochemistry, with particular focus on the work of the last decade. Being composed entirely of ions and possesing wide electrochemical windows (often in excess of 5 volts), it is not difficult to see why these compounds are seen by electrochemists as attractive potential solvents.

Use of room temperature ionic liquids in gas sensor design.

The attainable steady-state limiting currents and time responses of membrane-covered and membrane-independent gas sensors incorporating different electrode and electrolyte materials have been compared. A new design comprising a membrane-free microelectrode modified with a thin layer of a room temperature ionic liquid is considered. While the use of ionic liquid as electrolyte eliminates the need for a membrane and added supporting electrolyte, the slower diffusion of analyte within the more viscous medium results in slower time responses.