Spin control in ladderlike hexanuclear copper(II) complexes with metallacyclophane cores

Two new hexanuclear oxamatocopper(II) complexes 3 and 4 have been synthesized from the binuclear copper(II) complexes of the meta- and para-phenylenebis(oxamate) ligands, respectively. Complexes 3 and 4 possess an overall ladderlike structure made up of two oxamate-bridged linear trinuclear units ("rails") connected through two phenylenediamidate bridges ("rungs") between the central copper atoms to give metallacyclic cores of the meta- and para-cyclophane type, respectively. They show different ground spin states, S = 1 (3) or S = 0 (4), depending on the substitution pattern in the aromatic spacers. The triplet state molecule 3 containing two spin doublet Cu(II)3 units connected by two m-phenylenediamidate bridges represents a successful extension of the concept of "ferromagnetic coupling units" to metal complexes, which is a well-known approach toward high spin organic radicals.     

Slow magnetic relaxation in carbonato-bridged dinuclear lanthanide(III) complexes with 2,3-quinoxalinediolate ligands

The coordination chemistry of the 2,3-quinoxalinediolate ligand with different lanthanide(III) ions in basic media in air affords a new family of carbonato-bridged M(2)(III) compounds (M = Pr, Gd and Dy), the Dy(2)(III) analogue exhibiting slow magnetic relaxation behaviour typical of single-molecule magnets.     

Stereocontrolled total synthesis of amphidinolide X via a silicon-tethered metathesis reaction

Two esterifications and an RCM to create the challenging trisubstituted C12-C13 double bond were required in the total synthesis of amphidinolide X (1) reported here. Assembling the three fragments in this order, no RCM occurred or the process yielded mainly isomer Z. However, generating the E double bond first, by a new variant of a Si-tethered metathesis (using Schrock's catalyst), and carrying out the esterification and macrolactonization steps later, 1 was obtained exclusively.     

On theT(1)-theorem for the Cauchy integral

The main goal of this paper is to present an alternative, real variable proof of theT(1)-theorem for the Cauchy integral. We then prove that the estimate from below of analytic capacity in terms of total Menger curvature is a direct consequence of theT(1)-theorem. An example shows that theL ^∞-BMO estimate for the Cauchy integral does not follow fromL ² boundedness when the underlying measure is not doubling.     

Algebraic manipulation detection codes

Algebraic manipulation detection codes are a cryptographic primitive that was introduced by Cramer et al. (Eurocrypt 2008). It encompasses several methods that were previously used in cheater detection in secret sharing. Since its introduction, a number of additional applications have been found. This paper contains a detailed exposition of the known results about algebraic manipulation detection codes as well as some new results.     

Mono- and poly-nuclear nickel(II) complexes with nitrite and potentially bidentate amines as ligands

Summary Two new series of polynuclear complexes with potentially chelating amine and nitrite as ligands have been synthesized from octahedral dinitritobis(diamine)nickel(II) complexes (diamine = en, pn, tn or chxn). These complexes have been characterized by chemical analysis, electronic and i.r. spectra and magnetic measurements down to nitrogen liquid temperature. An x-ray structural investigation shows one of the starting materials, [Ni(tn)₂(NO₂)₂] to contain NO ₂ ^– groups coordinatedvia N(nitro complexes). One of the series of formula [Ni₅(diamine)₄(NO₂)₈(OH)₂], is pentanuclear, analogous to the en complex, whose structure is known. Another series is the polymeric Ni(amine)₂(NO₂)X, also an analogue of the en derivative. In the first series, the formation and isolation of the pentanuclear species has been achieved with en, tn, pn and chxn, but in the second series, only polynuclear complexes with en, tn and pn, were obtained. No product could be isolated for the more bulky chxn.     

Determination of free serotonin and its metabolite 5‐HIAA in blood human samples with consideration to pre‐analytical factors

Significant differences have been reported over the years in measuring physiological levels of free circulating serotonin (f5‐HT) in platelet‐poor plasma (PPP). This work shows that there are crucial pre‐analytical factors in sample manipulation that can provoke an artifactual release of 5‐HT from platelets, and that, even when the sample is accurately processed to obtain PPP, f5‐HT levels are approximately 2.8 times higher than those of f5‐HT in blood. An alternative methodology consisting of ex vivo blood microdialysis coupled to high‐performance liquid chromatography–electrochemical detection is proposed and validated. It is considered the most accurate technique to measure physiological circulating f5‐HT and its metabolite 5‐hydroxyindoleacetic acid (f5‐HIAA), owing to its sensitivity (limits of quantification of 0.08 ng/mL) and reliability since there is no sample manipulation. The f5‐HT and f5‐HIAA levels in blood and in PPP were studied in control subjects, hypertensive and end‐stage renal disease patients, who have a deregulated serotonergic system. This work reveals that blood is the best matrix to determine f5‐HT concentrations, and the clinical relevance of the accuracy of f5‐HT determination is discussed. Copyright © 2014 John Wiley & Sons, Ltd.