Additive Tuning of Redox Potential in Metallacarboranes by Sequential Halogen Substitution

The first artificially made set of electron acceptors is presented that are derived from a unique platform Cs[3,3′‐Co(C₂B₉H₁₁)₂], for which the redox potential of each differs from its predecessor by a fixed amount. The sequence of electron acceptors is made by substituting one, two, or more hydrogen atoms by chlorine atoms, yielding Cs[3,3′‐Co(C₂B₉H_11?yCl_y)(C₂B₉H_11?zCl_z)]. The higher the number of chlorine substituents, the more prone the platform is to be reduced. The effect is completely additive, so if a single substitution implies a reduction of 0.1 V of the redox potential of the parent complex, then ten substitutions imply a reduction of 1 V.     

Anellated N-heterocyclic carbenes: 1,3-dineopentylnaphtho[2,3-d]imidazol-2-ylidene: synthesis, KOH addition product, transition-metal complexes, and anellation effects

Two novel anellated N-heterocyclic carbenes (NHC), 1,3-dineopentylnaphtho[2,3-d]imidazol-2-ylidene, and 1,3-dineopentyl-2-ylido-imidazolo[4,5-b]pyridine were obtained by reduction of the respective thiones with potassium, the former also by deprotonation of the corresponding naphthimidazolium hexafluorophosphate by using excess KH in THF. The use of equimolar amounts of KH provided an unexpected formal addition product of this NHC with KOH. X-ray crystal structure analysis of the adduct provided evidence for a distorted tetrameric N-heterocyclic alkoxide, stabilized by two THF molecules. In C(6)D(6) the compound undergoes disproportionation. Transition-metal complexes [(NHC)AgCl], [(NHC)Rh(cod)Cl], and (E)-[(NHC)(2)PdCl(2)] of the novel naphthimidazol-2-ylidene were synthesized. X-ray crystal structures and (1)H and (13)C NMR spectroscopic data provided detailed structural information. Comparing characteristic data with those of nonanellated and differently anellated NHCs or their complexes provides information on the influence of the extended anellation.     

Topologically novel multiple rotaxanes and catenanes based on tetraurea calix[4]arenes

Calix[4]arenes bearing at their wide rim four urea residues easily form hydrogen bonded dimeric capsules. This has been used to preorganise alkenyl functions attached to these urea groups for their controlled connection via metathesis reaction. Multimacrocyclic tetraurea derivatives are thus obtained in excellent yields via heterodimers which are formed exclusively with tetratosylurea derivatives. Heterodimerisation of such bis- and tetraloop tetraureas leads analogously to multicatenanes, or to rotaxanes by stoppering. Huge macrocycles are detached from tetraloop derivatives by cleavage of the urea function.     

A comparison study between a disposable electrochemical DNA biosensor and a Vibrio fischeri-based luminescent sensor for the detection of toxicants in water samples

In the present study, a comparison between a disposable electrochemical DNA biosensor and a Vibrio fischeri-based luminescent sensor for the detection of toxicants in water samples was made.In order to realize this study, a disposable electrochemical DNA biosensor has been reported. The DNA biosensor is assembled by immobilizing double stranded Calf Thymus DNA onto the surface of a disposable carbon screen-printed electrode. The oxidation signal of the guanine base, obtained by a square wave voltammetric scan, is used as analytical signal to detect the DNA damage; the presence of low molecular weight compounds with affinity for nucleic acids is measured by their effect on the guanine oxidation peak.Wastewater samples provided during First European Interlaboratory Exercise on water toxicity in the course of the project SWIFT-WFD were analyzed, and biosensor results were compared with a currently used toxicity test ToxAlert^®100 based on the bioluminescence inhibition of Vibrio fischeri. This test have been used because is rapid, easy handling and cost effectively responses for the toxicity assessment in real water samples.The results showed a promising correlation between two tests used for the detection of toxic compounds in water samples.     

On neutrino masses via CPT violating Higgs interaction in the Standard Model

The Lorentz invariant CPT   violation by using non-local interactions is naturally incorporated in the Higgs coupling to neutrinos in the Standard Model, without spoiling the basic SU_(2)L×U(1)$\mathit{SU}{(2)}_L\times U(1)$ gauge symmetry. The neutrino–antineutrino mass splitting is thus realized by the mechanism which was proposed recently, assuming the neutrino masses to be predominantly Dirac-type in the Standard Model.     

Behavior of soybean oil-in-water emulsion stabilized by nonionic surfactant

A soybean oil-in-water emulsion was prepared using nonionic Tween series surfactants. The effects of temperature, hydrophilic-lipophilic balance (HLB) value of the surfactant, and surfactant-to-oil ratio on the size of emulsion drops were investigated with an acoustic and electroacoustic devices. In the case of Tween 85, the influence of pH and electrolyte on the zeta potential of emulsion drops was examined. zeta potential appears to be strongly dependent on pH, varying in the case of high concentrations of NaCl from +60 to -90 mV. High concentrations of Na+ and K+ are capable of separating the oil phase from the emulsion. Divalent cations such as Ca2+ and Mg2+ lead to two points of zero charge at high concentrations, which is not observed for the case of hydrolyzable trivalent species like Al3+ and Fe3+.     

Radioimmunoanalysis of antibodies obtained by a liposomal adjuvant

An experimental model for preparing and testing by the radioimmunoanalysis (RIA) method the immunoadjuvant capacity of the dehydration-rehydration vesicles (DRV) over the Freund complete adjuvant (FCA) is presented. The humoral antibody response to bovine serum albumin (BSA), human transferrin and human alphafoetoprotein was investigated on rats. The concentration of specific antibodies (a) and the average antibody affinity, constant (k) are the two intrinsic parameters of the antisera measured by RIA we referred to. The experimental results show thatk is higher anda is smaller for the liposomal adjuvant than for the Freund one.     

New Ca2+ fluoroionophores based on the BODIPY fluorophore

Calcium (Ca(2+)) fluoroionophores are useful in cell-based functional assays of G-protein coupled receptor (GPCR) activation or ion channel modulation. In this paper we describe new calcium probes that improve or overcome certain deficiencies in existing probes. These new fluoroionophores are based on acylation of amino-BAPTA [BAPTA = glycine, N,N'-(1,2-ethanediyl-bis(oxy-2,1-phenylene)) bis(N-(carboxymethyl))] with fluorescent BODIPY(R) propionates [BODIPY = 4,4-difluoro-5,7-dimethyl- 4-bora-3a,4a-diaza-s-indacene]. The resulting probes show high affinity to aqueous calcium solutions, and respond to calcium binding with significant fluorescence increases. The BODIPY fluorophores are uncharged and their fluorescence is pH-insensitive. The wide range of excitation/emission wavelength choices available within the BODIPY fluorophore series allows several different colors of new calcium indicators to be prepared. Cell permeable versions respond well with increasing fluorescence intensities in live cells after calcium influx.