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Thallium is considered to be an environmental threat; however, its hazardous properties depend on its oxidation state. Tl(III) is approx. 1000-times more toxic compared with Tl(I), therefore identification of each species is essential in order to properly evaluate the associated health hazard. Electrospray ionization mass spectrometry (ESI-MS) allows determination of speciation in solution due to its soft mode of ionization while selective complexation with ligands can distinguish the Tl species. Selective complexation of Tl(I) and Tl(III) ions requires the use of two selective complexing agents and selection of appropriate conditions for this process.Tl(I) and Tl(III) ions as well as two ligands (EDTA and DTPA) were used to form binary (single ion + single ligand), ternary (one ion + both ligands) and quaternary systems (both ions and both ligands) under different pH conditions (7 and 8). These mixtures were subjected to the determination of Tl species using ESI-MS operating in positive and negative ion mode.Tl(I) complexes with DTPA were identified at pH 7 and 8, whereas, in the case of EDTA, the complexes were detected only at pH 8. In contrast, Tl(III) formed distinct complexes with EDTA at pH 7 and 8, while with DTPA the complexes were detected only at pH 8. Analysis of the quaternary system (which contained both ions and both ligands) revealed that Tl(I) formed complexes with EDTA, while Tl(III) formed complexes with DTPA at pH 7 and 8.The obtained results confirmed that the increase in the solution complexity allowed simultaneous identification of different complexes in solutions containing both Tl species. The initial analyses carried out for binary and ternary solutions facilitated the simultaneous determination of specific complexes (Tl(I) with EDTA and Tl(III) with DTPA) in the quaternary system.

Over the past four decades, the patch clamp technique and nicotinic ACh (nACh) receptors have established an enduring partnership. Like all good partnerships, each partner has proven significant in its own right, while their union has spurred innumerable advances in life science research. A member and prototype of the superfamily of pentameric ligand-gated ion channels, the nACh receptor is a chemo-electric transducer, binding ACh released from nerves and rapidly opening its channel to cation flow to elicit cellular excitation. A subject of a Nobel Prize in Physiology or Medicine, the patch clamp technique provides unprecedented resolution of currents through single ion channels in their native cellular environments. Here, focusing on muscle and α7 nACh receptors, we describe the extraordinary contribution of the patch clamp technique towards understanding how they activate in response to neurotransmitter, how subtle structural and mechanistic differences among nACh receptor subtypes translate into significant physiological differences, and how nACh receptors are being exploited as therapeutic drug targets.

4-Methoxy-2-methyl-2-butanethiol is a powerful sulfur-containing aroma compound identified several decades ago in blackcurrant buds (Ribes nigrum L.). However, an unambiguous identification in blackcurrant fruits has been lacking. In this study the occurrence of 4-methoxy-2-methyl-2-butanethiol in blackcurrant berries has been demonstrated for the first time by the analysis of seven cultivars. After isolation of the volatiles by vacuum-headspace-extraction, the sulfur-containing compound was enriched on mercurated agarose gel. Identification was performed via capillary gas chromatography/mass spectrometry. Quantitation was performed in the single ion monitoring mode using 4-methyl-4-sulfanylpentan-2-one as internal standard. The concentration of 4-methoxy-2-methyl-2-butanethiol in Andega (4.5 µg/kg) was significantly higher than those in the other cultivars investigated in this study (from 0.16 to 0.72 µg/kg). Calculation of the odour activity values indicated that this sulfur-containing volatile contributes to the aroma of blackcurrant berries. Copyright © 2016 John Wiley & Sons, Ltd.

This article elucidates the pitfalls identified in the software package SIMPRE recently developed by Baldovi et al. (J. Comput. Chem. 2013, 34, 1961) for modeling the spectroscopic and magnetic properties of single ion magnets as well as single-molecule magnets. Analysis of the methodology used therein reveals that the crystal field parameters (CFPs), expressed nominally in the Stevens formalism, exhibit features characteristic for the CFPs expressed in the Wybourne notation. The resemblance of the two types of CFPs introduces a serious confusion that may lead to wrong comparisons of the CFPs taken from various sources. To clarify this confusion, the properties of the CFPs Bkq ( Akq, Ckq) associated with the Stevens operators Okq(X = S, J, or L), which belong to the class of the tesseral-tensor operators, are contrasted with those of the CFPs Bkq associated with the Wybourne operators Cq(k), which belong to the class of the spherical-tensor operators. Importantly, the confused properties of Stevens and Wybourne operators may bear on reliability of SIMPRE calculations. To consider this question independent calculations are carried out using the complete approach and compared with those of the restricted approach utilized earlier. It appears that the numerical results of the package SIMPRE are formally acceptable, however, the meaning of the CFPs must be properly reformulated. Several other conceptual problems arising from misinterpretations of the crucial notions and the CFP notations identified therein are also discussed and clarified.

The formation of a metal-organic framework (MOF) with nodes that have single-molecule magnet (SMM) behaviour has been achieved by using mononuclear lanthanoid analogues, also known as single-ion magnets (SIMs), which enormously simplifies the challenging issue of making SMM-MOFs. Here we present a rational design of a family of MOFs, [Ln(bipyNO)4](TfO)3⋅x solvent (Ln=Tb (1); Dy (2); Ho (3); Er (4); TfO=triflate), in which the lanthanoid centres have an square-antiprismatic coordination environment suitable for SIM behaviour. Magnetic measurements confirm the existence of slow magnetic relaxation typical of SMMs, which has been rationalised by means of a radial effective charge model. In addition, we have explored the incorporation of bulky polyoxometalates (POMs) into the cavities of the SIM-MOF by anion exchange, finding that they do not interfere with the slow magnetic relaxation. This demonstrates the robustness of the frameworks and opens the possibility of incorporating non-innocent anions.

The experimental approach of this work was to develop a new method for the quantification of saturated MAGs in biodiesel using GC–MS. The method was established on a 30 m 5% phenyl phase column and ensured satisfying separation of the target MAGs. The quantification of the saturated MAGs was carried out in single ion monitoring (SIM) mode using the quantitation ions for the target MAGs: m/z 218 (2-C16:0), m/z 371 (1-C16:0), m/z 385 (1-C17:0), and 399 (1-C18:0) as well as m/z 413 for 1-C19:0, serving as an internal standard (IS). The analytical procedure involved mixing the biodiesel sample with the IS and a silylating agent before applying GC–MS analysis. Response factors for the individual target MAGs related to the IS were determined. Prior to the quantification of saturated MAGs in real biodiesel samples, derived from used cooking oil (UCO) and waste animal fats (WAF), the linearity (R2>0.99) and the limits of detection and quantification (LOD: 8–20 ng/g, LOQ: 26–61 ng/g) of the method were determined. Practical applications: The European Committee for Standardization (CEN) contemplates to establish a limit value specifically for saturated MAGs in biodiesel, primarily requiring a specific analysis method. At present, there is no suitable test method for the determination of saturated monoglycerol content in FAME. Therefore, the approach of this work was to develop a new method for the quantification of saturated MAGs in biodiesel using GC–MS. In contrast to the currently valid European standard method EN 14105 for the determination of free glycerol, mono-, di- (MAGs, DAGs), and triacylglycerols (TAGs), this new method features a very high sensitivity and enables the exclusion of interfering substances, both due to performing the analysis in single ion monitoring mode (SIM).

Single-molecule magnets (SMMs) that contain one spin centre (so-called single-ion magnets) theoretically represent the smallest possible unit for spin-based electronic devices. The realisation of this and related technologies, depends on first being able to design systems with sufficiently large energy barriers to magnetisation reversal, Ueff, and secondly, on being able to organise these molecules into addressable arrays. In recent years, significant progress has been made towards the former goal - principally as a result of efforts which have been directed towards studying complexes based on highly anisotropic lanthanide ions, such as Tb(iii) and Dy(iii). Since 2013 however, and the remarkable report by Long and co-workers of a linear Fe(i) system exhibiting Ueff = 325 K, single-ion systems of transition metals have undergone something of a renaissance in the literature. Not only do they have important lessons to teach us about anisotropy and relaxation dynamics in the quest to enhance Ueff, the ability to create strongly coupled spin systems potentially offers access to a whole of host of 1, 2 and 3-dimensional materials with interesting structural and physical properties. This perspective summarises recent progress in this rapidly expanding sub-genre of molecular magnetism from the viewpoint of the synthetic chemist, with a particular focus on the lessons that have so far been learned from single-ion magnets of the d-block, and, the future research directions which we feel are likely to emerge in the coming years.

A series of homoleptic ([Tb(III)(Pc)(2) ]) and heteroleptic ([Tb(III)(Pc)(Pc')]) Tb(III) bis(phthalocyaninate) complexes that contain different peripheral substitution patterns (i.e., tert-butyl or tert-butylphenoxy groups) have been synthesized in their neutral radical forms and then reduced into their corresponding anionic forms as stable tetramethylammonium/tetrabutylammonium salts. All of these compounds were spectroscopically characterized and their magnetic susceptibility properties were investigated. As a general trend, the radical forms exhibited larger energy barriers for spin reversal than their corresponding reduced compounds. Remarkably, heteroleptic complexes that contain electron-donor moieties on one of the two Pc ligands show higher effective barriers and blocking temperatures than their homoleptic derivatives. This result is assigned to the elongation of the N-Tb distances in the substituted macrocycle, which brings the terbium(III) ion closer to the unsubstituted Pc, thus enhancing the ligand-field effect. In particular, heteroleptic [Tb(III) (Pc)(Pc')] complex 4, which contains one octa(tert-butylphenoxy)-substituted Pc ring and one bare Pc ring, exhibits the highest effective barrier and blocking temperature for a single-molecule magnet reported to date.

Using the example of Li-battery electrolytes, the importance of the concept of conservative ensembles for polarization behavior and transference measurements of salt-containing liquid electrolytes is stressed. The conventional evaluation of the stationary values fails if the ion pair is mobile and can act as a vehicle of a single ion such as Li+. The necessary generalization is considered. While the analytical form of the time dependence of voltage or current is not affected provided the ion pairing is sufficiently fast, the diffusion coefficient contains nontrivial extra contributions. Finally, soggy-sand electrolytes are inspected, in which polarization occurs in the space-charge zones.

A study has been made of the influence of substitution by alkyl and phenyl groups in organic acids and bases on the interaction of the ions of these substances with the solvent. Knowledge of single ion activity coefficients is essential for the interpretation of the different effects.

The paper presents a study of the Ph4AsPh4B assumption as for verification of its plausibility for the determination of thermodynamic quantities of single ions in mixed dimethylsulfoxide (DMSO)-water solvents. For discussion the solvation energy is considered as a composite of electrostatic and neutral components. The neutral components are replaced by experimental data of Ph4Ge and Ph4C which are proved to be equal, of their size and structure, to the reference cation and anion. The electrostatic components are obtained by calculation according to the theory in the literature. The results of the present investigation provide the conclusion that an assymmetric partition is preferred to an equal partition practiced in the literature. Based on the study, the standard free energies of transfer for single ions, Ph4As+, Ph4B, Cs+ and I−, are determined and for others, H+, Li+, Na+, K+, Rb+, Cl− and Br− evaluated from the data of salts known in the literature. Discussion is elaborated with solvation properties of individual ions.

The partitioning of thermodynamic quantities of the reference electrolyte (Ph4AsPh4B) is discussed by comparing its standard free energies of transfer from water to organic solvents (ΔWSG°) with those for Ph4AsPh4B. From experiment in 14 different dipolar-aprotic organic solvents, it is found that an asymmetric partition with the ratio: ΔWSG° (Ph4As+)/ΔWSG° (Ph4B−)=1.08 ± 0.02 is better justified than the equal partition practised in the literature. This asymmetry is mainly ascribed to the size difference between the reference cation and anion. The electrostatic contribution (ΔWSG°A(el)), primarily from iondipole interaction, does not appear as a cause for the asymmetry.

The single ion magnetic anisotropy of S-state transition metal ions (3d 5 ) in wurtzite diluted magnetic semiconductors (DMS) is studied from a microscopic point of view. Starting from a hamiltonian including Coulomb, spin-orbit and effective crystal field interactions, the axial spin hamiltonian parameter is calculated by using an exact diagonalization method. Application to some Mn-doped DMS validates the model.

On the Individual Thermodynamic Activity Coefficients of Single Ion Species in Electrolyte Solutions at High Concentrations The individual activity coefficients of the single ion species, which are produced by dissociation of aqueous electrolytes, are necessary for the thermodynamic treatment of equilibrations and processes involving electrolytes. The determination of these values is one of the basic quests of electrochemistry and a controversial topic. This problem is unsolvable using classical thermodynamics. In this paper a mathematical method is shown, which can be used to split the mean activity coefficients into the values for the individual ion species of an electrolyte. For this determination the mean activity coefficients have to be expressed in the power form of equation. The concept based on the adaptation of a product function for the concentration development of the mean activity coefficients to the experimental data and their separation into factor functions of a predefined structure, which represent the concentration development of the individual activity coefficients of the single ion species of the electrolyte. This mathematical method was used to calculate the individual activity coefficients of the single ion species of alkali chlorides, alkaline earth chlorides, alkaline earth perchlorates, hydrohalic acids and alkali hydroxides. In summary, all the calculated single ion activity coefficients are in good agreement with the expected theoretical considerations. A proportionality to the reciprocal diameter of the unhydrated cation is clearly recognizable. The calculated individual activity coefficients correspond in every case with the assumption about their size, which can be reproduced using a variety of electrochemical investigations and experiments.

Review: single-molecule magnets consisting of one first row transition metal ion in a suitable ligand field; 52 refs.

The phase diagram of the ABpC1–p ternary alloy consisting of different Ising spins SA = 3/2, SB = 2, and SC = 5/2 in the presence of a single-ion anisotropy is investigated by the use of a mean-field theory. At finite temperature by changing values of the parameters of the model different types of phase diagrams are obtained, including critical end points and isolated critical points. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An extract of the Great Australian Bight marine sponge Callyspongia sp. (CMB-01152) displayed inhibitory activity against the neurodegenerative disease kinase targets casein kinase 1 (CK1), cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3 (GSK3β). Chemical investigation, employing HPLC-DAD-MS single ion extraction protocols, facilitated identification of the new bromopyrrole alkaloids, callyspongisines A–D (1–4), and two known co-metabolites, hymenialdisine (5) and 2-bromoaldisine (6). Structure elucidation of 1–6 was supported by detailed spectroscopic analysis and chemical interconversion, as well as biosynthetic and synthetic considerations. Callyspongisine A (1) is only the second reported example of a natural imino-oxazoline, and the first to feature a spiro heterocyclic framework, while callyspongisines B–D (2–4) were speculated to be storage and handling artefacts of 1. The kinase inhibitory activity detected in Callyspongia sp. (CMB-01152) was attributed to 5.

Single crystals of [LnZn6(μ3-OH)(gly)6 (μ2-NO3)3] (OH)(NO3)2·8H2O (gly: glycine, Ln: Dy (I), Er (II)) are prepared in yields of about 50% for (I) and 53% for (II) by evaporating H2O/MeCN/MeOH (2:5:10) solutions of Ln(NO3)3, Zn(NO3)2, glycine, isobutyric lithium, and LiOH.

trans-4-Hydroxy-2-nonenal (HNE) is an end-product of lipid peroxidation in biological systems which produces a variety of powerful biological effects. A method based on electrospray mass spectrometry was developed for the determination of 4-HNE at cellular levels. Quantification was carried out by using HNE-d(11) as internal standard; the mass chromatograms were acquired in the single ion monitoring mode (SIM) on the [M + H](+) monoisotopic species for HNE and HNE-d(11). With this approach a higher precision and lower detection limit and biological sample size than those typical of the methods so far employed are achieved. Furthermore the determination of the analyte from the cell extract is directly performed without the need of any HNE derivatization. As a first application the method was used to identify and quantify HNE in human T cell leukemia extracts.

The fine structure of ion-channel activations by junctional nicotinic receptors in adult frog muscle fibres has been investigated. The agonists used were acetylcholine (ACh), carbachol (CCh), suberyldicholine (SubCh) and decan-1,10-dicarboxylic acid dicholine ester (DecCh). Individual activations (bursts) were interrupted by short closed periods; the distribution of their durations showed a major fast component ('short gaps') and a minor slower component ('intermediate gaps'). The mean duration of both short and intermediate gaps was dependent on the nature of the agonist. For short gaps the mean durations (microseconds) were: ACh, 20; SubCh, 43; DecCh, 71; CCh, 13. The mean number of short gaps per burst were: ACh, 1.9; SubCh, 4.1; DecCh, 2.0. The mean number of short gaps per burst, and the mean number per unit open time, were dependent on the nature of the agonist, but showed little dependence on agonist concentration or membrane potential for ACh, SubCh and DecCh. The short gaps in CCh increased in frequency with agonist concentration and were mainly produced by channel blockages by CCh itself. Partially open channels (subconductance states) were clearly resolved rarely (0.4% of gaps within bursts) but regularly. Conductances of 18% (most commonly) and 71% of the main value were found. However, most short gaps were probably full closures. The distribution of burst lengths had two components. The faster component represented mainly isolated short openings that were much more common at low agonist concentrations. The slower component represented bursts of longer openings. Except at very low concentrations more than 85% of activations were of this type, which corresponds to the 'channel lifetime' found by noise analysis. The frequency of channel openings increased slightly with hyperpolarization. The short gaps during activations were little affected when (a) the [H+]o or [Ca2+]o were reduced to 1/10th of normal, (b) when extracellular Ca2+ was replaced by Mg2+, (c) when the [Cl-]i was raised or (d) when, in one experiment on an isolated inside-out patch, the normal intracellular constituents were replaced by KCl. Reduction of [Ca2+]O to 1/10 of normal increased the single-channel conductance by 50%, and considerably increased the number of intermediate gaps. No temporal asymmetry was detectable in the bursts of openings. Positive correlations were found between the lengths of successive apparent open times at low SubCh concentrations, but no correlations between burst lengths were detectable. The component of brief openings behaves, at low concentrations, as though it originates from openings of singly occupied channels.(ABSTRACT TRUNCATED AT 400 WORDS)

A direct ion imaging system with single ion detection and high-precision imaging modes has been developed. This system is composed of a movable microchannel plate unit and a stacked CMOS-type active pixel sensor (SCAPS). Capabilities of single ion detection were evaluated by ion irradiations using secondary ion mass spectrometry. The experiment shows that this system accurately detected single incident ions. Copyright © 2006 John Wiley & Sons, Ltd.

1. Conductance of heterotrimeric rat epithelial Na+ channels (alpha, beta, gamma-rENaCs) for Li+ and Na+ in planar lipid bilayers was a non-linear function of ion concentration, with a maximum of 30.4 +/- 2.9 pS and 18.5 +/- 1.9 pS at 1 M Li+ and Na+, respectively. 2. The alpha, beta, gamma-rENaC conductance measured in symmetrical mixtures of Na(+)-Li+ (1 M) exhibited an anomalous mole fraction dependence, with a minimum at 4:1 Li+ to Na+ molar ratio. 3. Permeability ratios PK/PNa and PLi/PNa of the channel calculated from the bionic reversal potentials were dependent on ion concentration: PK/PNa was 0.11 +/- 0.01, and PLi/PNa was 1.6 +/- 0.3 at 50 mM; PK/PNa was 0.04 +/- 0.01 and PLi/PNa was 2.5 +/- 0.4 at 3 M, but differed from the ratios of single-channel conductances in symmetrical Li+, Na+ or K+ solutions. The permeability sequence determined by either method was Li+ > Na+ > K+ >> Rb+ Cs+. 4. Predictions of a model featuring two binding sites and three energy barriers (2S3B), and allowing double occupancy, developed on the basis of single ion current-voltage relationships, are in agreement with the observed conductance maximum in single ion experiments, conductance minimum in the mole fraction experiments, non-linearity of the current-voltage curves in bionic experiments, and the concentration dependence of permeability ratios. 5. Computer simulations using the 2S3B model recreate the ion concentration dependencies of single-channel conductance observed for the immunopurified bovine renal amiloride-sensitive Na+ channel, and short-circuit current in frog skin, thus supporting the hypothesis that ENaCs form a core conduction unit of epithelial Na+ channels.

This work was supported by the MINECO (Spain) (Project CTQ2011-24478), the Junta de Andalucía (FQM-195 and Project of excellence P08-FQM-03705), and the University of Granada. E.R. and E.Cr. thank MINECO grant No. CTQ2011-23862-C02-01 and Generalitat de Catalunya grant No. 2009SGR-1459, for financial support. We would like to thank Prof. Liviu Chibotaru for providing us the SINGLE_ANISO program and Dr. Andrew Ozarowski for the EPR simulation software. E.K.B. thanks the EPSRC and Leverhulme Trust for financial support. The NHMFL is funded by the NSF, DoE, and the state of Florida. J.C. acknowledges financial support by the Spanish Ministerio de Ciencia e Innovación through projects CTQ2010-15364, Molecular Nanoscience (Consolider Ingenio CSD2007-00010), and Generalitat Valenciana (PROMETEO/2009/108). W.W. acknowledges the ARN-PNANO project MolNanoSpin No. ANR-08-NANO- 002 and the ERC Advanced Grant MolNanoSpin No. 226558. J.K. acknowledges NSF grant DMR 1157490., The complex [Co(µ-L)(µ-OAc)Y(NO3)2], in which the Co(II) ion exhibits a D value of ~+45 cm-1 as determined by magnetic and inelastic neutron scattering experiments, exhibits slow magnetic relaxation and Single-Ion Magnet behaviour., MINECO (Spain) CTQ2011-24478, Junta de Andalucía FQM-195 P08-FQM-03705, University of Granada, MINECO CTQ2011-23862-C02-01, Generalitat de Catalunya 2009SGR-1459, Engineering & Physical Sciences Research Council (EPSRC), Leverhulme Trust, National Science Foundation (NSF) DMR 1157490, United States Department of Energy (DOE), State of Florida, Instituto de Salud Carlos III Spanish Government CTQ2010-15364 CSD2007-00010, Generalitat Valenciana PROMETEO/2009/108, ARN-PNANO project MolNanoSpin ANR-08-NANO-002, European Research Council (ERC) 226558, Engineering & Physical Sciences Research Council (EPSRC) EP/L010615/1

The compounds K12LnP5W30O110 ·nH2O (Ln3+: Tb, Dy, Ho, Er, Tm, and Yb) are prepared from aqueous solutions of K12.5Na1.5 [NaP5W30O110] and LnCl3 (autoclave, 160 °C, 24 h) and characterized by static and dynamic magnetic measurements.