A N3S(thioether)-ligated Cu(II)-superoxo with enhanced reactivity.

Previous efforts to synthesize a cupric superoxide complex possessing a thioether donor have resulted in the formation of an end-on trans-peroxo-dicopper(II) species, [{(Ligand)Cu(II)}2(μ-1,2-O2(2-))](2+). Redesign/modification of previous N3S tetradentate ligands has now allowed for the stabilization of the monomeric, superoxide product possessing a S(thioether) ligation, [((DMA)N3S)Cu(II)(O2(•-))](+) (2(S)), as characterized by UV-vis and resonance Raman spectroscopies. This complex mimics the putative Cu(II)(O2(•-)) active species of the copper monooxygenase PHM and exhibits enhanced reactivity toward both O-H and C-H substrates in comparison to close analogues [(L)Cu(II)(O2(•-))](+), where L contains only nitrogen donor atoms.

Lewis acid-induced change from four- to two-electron reduction of dioxygen catalyzed by copper complexes using scandium triflate.

Mononuclear copper complexes, [(tmpa)Cu(II)(CH3CN)](ClO4)2 (1, tmpa = tris(2-pyridylmethyl)amine) and [(BzQ)Cu(II)(H2O)2](ClO4)2 (2, BzQ = bis(2-quinolinylmethyl)benzylamine)], act as efficient catalysts for the selective two-electron reduction of O2 by ferrocene derivatives in the presence of scandium triflate (Sc(OTf)3) in acetone, whereas 1 catalyzes the four-electron reduction of O2 by the same reductant in the presence of Brønsted acids such as triflic acid. Following formation of the peroxo-bridged dicopper(II) complex [(tmpa)Cu(II)(O2)Cu(II)(tmpa)](2+), the two-electron reduced product of O2 with Sc(3+) is observed to be scandium peroxide ([Sc(III)(O2(2-))](+)). In the presence of 3 equiv of hexamethylphosphoric triamide (HMPA), [Sc(III)(O2(2-))](+) was oxidized by [Fe(bpy)3](3+) (bpy = 2,2-bipyridine) to the known superoxide species [(HMPA)3Sc(III)(O2(•-))](2+) as detected by EPR spectroscopy.

Increasing the supply of kidneys for transplantation by making living donors the preferred source of donor kidneys.

At the present time, increasing the use of living donors offers the best solution to the organ shortage problem. The clinical questions raised when the first living donor kidney transplant was performed, involving donor risk, informed consent, donor protection, and organ quality, have been largely answered. We strongly encourage a wider utilization of living donation and recommend that living donation, rather than deceased donation, become the first choice for kidney transplantation.

Crystallographic and spectroscopic characterization and reactivities of a mononuclear non-haem iron(III)-superoxo complex.

Mononuclear non-haem iron(III)-superoxo species (Fe(III)-O2(-·)) have been implicated as key intermediates in the catalytic cycles of dioxygen activation by non-haem iron enzymes. Although non-haem iron(III)-superoxo species have been trapped and characterized spectroscopically in enzymatic and biomimetic reactions, no structural information has yet been obtained. Here we report the isolation, spectroscopic characterization and crystal structure of a mononuclear side-on (η(2)) iron(III)-superoxo complex with a tetraamido macrocyclic ligand.

Redox-active ligand-induced homolytic bond activation.

Coordination of the novel redox-active phosphine-appended aminophenol pincer ligand (PNO(H2) ) to Pd(II) generates a paramagnetic complex with a persistent ligand-centered radical. The complex undergoes fully reversible single-electron oxidation and reduction. Homolytic bond activation of diphenyldisulfide by the single-electron reduced species leads to a ligand-based mixed-valent dinuclear palladium complex with a single bridging thiolate ligand.

Influence of selenocyanate ligands on the transition temperature and cooperativity of bapbpy-based Fe(II) spin-crossover compounds.

Coordination of the ligand bapbpy (1, bapbpy = N,N'-di(pyrid-2-yl)-2,2'-bipyridine-6,6'-diamine), of one of its four dimethyl-substituted analogues 2-5 (R2bapbpy = N,N'-di(methylpyrid-2-yl)-2,2'-bipyridine-6,6'-diamine), or of one of its three bis(iso)quinoline analogues 6-8 (R2bapbpy= N,N'-di(quinolyl)-2,2'-bipyridine-6,6'-diamine), to Fe(NCSe)2, afforded eight new iron(II) compounds of the type [Fe(R2bapbpy)(NCSe)2] (9-16). Three of these compounds (11, 13, and 16) were structurally characterized by single crystal X-ray diffraction, which showed similar molecular geometry and packing compared to their thiocyanate analogues. Magnetic susceptibility measurements were carried out for all iron compounds and revealed thermal spin-crossover (SCO) behavior for compounds 9, 11, 13, 15, and 16.

Determination of the stereochemistry of the aggregation pheromone of harlequin bug, Murgantia histrionica.

Preparation of a complete stereoisomeric library of 1,10-bisaboladien-3-ols and selected 10,11-epoxy-1-bisabolen-3-ols was pivotal for the identification of the aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys. Herein, we describe syntheses of the remaining 10,11-epoxy-1-bisabolen-3-ols, and provide additional evidence on the assignment of relative and absolute configurations of these compounds by single-crystal X-ray crystallography of an intermediate, (3S,6R,7R,10S)-1-bisabolen-3,10,11-triol. To demonstrate the utility of this stereoisomeric library, we revisited the aggregation pheromone of the harlequin bug, Murgantia histrionica, and showed that the male-produced pheromone consists of two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol.

Protonation of a biologically relevant Cu(II) μ-thiolate complex: ligand dissociation or formation of a protonated Cu(I) disulfide species?

The proton-induced electron-transfer reaction of a Cu(II) μ-thiolate complex to a Cu(I) -containing species has been investigated, both experimentally and computationally. The Cu(II) μ-thiolate complex [Cu(II) 2 (L(Me) S)2 ](2+) is isolated with the new pyridyl-containing ligand L(Me) SSL(Me) , which can form both Cu(II) thiolate and Cu(I) disulfide complexes, depending on the solvent. Both the Cu(II) and the Cu(I) complexes show reactivity upon addition of protons.

Speciation of ferric phenoxide intermediates during the reduction of iron(III)-μ-oxo dimers by hydroquinone.

The aqueous speciation of iron(III)-tris(pyridylmethyl)amine (TPA) complexes was determined from potentiometric titration data, and the overall formation constants (β) for relevant species were calculated. At pH < 3 the mononuclear complex [Fe(TPA)](+3)(aq) predominates (log β = 10.75(15).

Surgeon-family perioperative communication: surgeons' self-reported approaches to the "surgeon-family relationship".

Background: Family members are important in the perioperative care of surgical patients. During the perioperative period, communication about the patient occurs between surgeons and family members. To date, however, surgeon-family perioperative communication remains unexplored in the literature.

Direct observation of a nonheme iron(IV)-oxo complex that mediates aromatic C-F hydroxylation.

The synthesis of a pentadentate ligand with strategically designed fluorinated arene groups in the second coordination sphere of a nonheme iron center is reported. The oxidatively resistant fluorine substituents allow for the trapping and characterization of an Fe(IV)(O) complex at -20 °C. Upon warming of the Fe(IV)(O) complex, an unprecedented arene C-F hydroxylation reaction occurs.

Thermodynamics of the Cu(II) μ-thiolate and Cu(I) disulfide equilibrium: a combined experimental and theoretical study.

The redox equilibrium between dinuclear Cu(II) μ-thiolate and Cu(I) disulfide structures has been analyzed experimentally and via DFT calculations. Two new ligands, L(2)SSL(2) and L(4)SSL(4), and their Cu(II) μ-thiolate and Cu(I) disulfide complexes were synthesized. For L(2)SSL(2), these two redox-isomeric copper species are shown to be in equilibrium, which depends on both temperature and solvent.

Search for a strong, virtually "no-shift" hydrogen bond: a cage molecule with an exceptional OH⋅⋅⋅F interaction.

Reported herein is the synthesis of a molecule containing an unusually strong hydrogen bond between an OH donor and a covalent F acceptor, a heretofore somewhat ill-defined if not controversial interaction. This unique hydrogen bond is to a large extent a product of the tight framework of the rigid caged system. Remarkably, the interaction shows little to no perceptible shift in the OH stretch of the IR spectrum relative to appropriate nonhydrogen-bound standards in fairly non-interactive solvents.

Discovery of the aggregation pheromone of the brown marmorated stink bug (Halyomorpha halys) through the creation of stereoisomeric libraries of 1-bisabolen-3-ols.

We describe a novel and straightforward route to all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol via the rhodium-catalyzed asymmetric addition of trimethylaluminum to diastereomeric mixtures of cyclohex-2-enones 1 and 2. The detailed stereoisomeric structures of many natural sesquiterpenes with the bisabolane skeleton were previously unknown because of the absence of stereoselective syntheses of individual stereoisomers. Several of the bisabolenols are pheromones of economically important pentatomid bug species.

Direct, catalytic monofluorination of sp³ C-H bonds: a radical-based mechanism with ionic selectivity.

Recently, our group unveiled a system in which an unusual interplay between copper(I) and Selectfluor effects mild, catalytic sp(3) C-H fluorination. Herein, we report a detailed reaction mechanism based on exhaustive EPR, (19)F NMR, UV-vis, electrochemical, kinetic, synthetic, and computational studies that, to our surprise, was revealed to be a radical chain mechanism in which copper acts as an initiator. Furthermore, we offer an explanation for the notable but curious preference for monofluorination by ascribing an ionic character to the transition state.

Tuning of the copper-thioether bond in tetradentate N₃S(thioether) ligands; O-O bond reductive cleavage via a [Cu(II)₂(μ-1,2-peroxo)]²⁺/[Cu(III)₂(μ-oxo)₂]²⁺ equilibrium.

Current interest in copper/dioxygen reactivity includes the influence of thioether sulfur ligation, as it concerns the formation, structures, and properties of derived copper-dioxygen complexes. Here, we report on the chemistry of {L-Cu(I)}2-(O2) species L = (DMM)ESE, (DMM)ESP, and (DMM)ESDP, which are N3S(thioether)-based ligands varied in the nature of a substituent on the S atom, along with a related N3O(ether) (EOE) ligand. Cu(I) and Cu(II) complexes have been synthesized and crystallographically characterized.

Ethical considerations for clinical trials in inflammatory bowel disease.

Although advancements in the field of inflammatory bowel disease (IBD) include effective therapies for many patients with Crohn's disease and ulcerative colitis, there remains a large unmet need, and there is a large number of investigational agents in the pipeline. Drug development through clinical trials is critical to understanding the safety and efficacy of new therapies in the affected human population, and the need for ethical trial design is of the utmost importance. This paper explores the ethical issues of clinical trials in IBD, focusing on placebo-controlled trials, vulnerable patients, exposure to monoclonal antibodies, globalization of trials, and surgical advances.

History and evolution of surgical ethics: John Gregory to the twenty-first century.

As surgery grew to become a respected medical profession in the eighteenth century, medical ethics emerged as a response to the growing need to protect patients and maintain the public's trust in physicians. The early influences of John Gregory and Thomas Percival were instrumental in the formulation of patient-centered medical ethics. In the late nineteenth century, the modern surgical advances of anesthesia and antisepsis created the need for a discipline of ethics specific to surgery in order to confront new and evolving ethical issues.

Control of the iridium oxidation state in the hollandite iridate solid solution K(1-x)Ir4O8.

The synthesis and physical properties of the K(1-x)Ir4O8 (0 ≤ x ≤ 0.7) solid solution are reported. The structure of KIr4O8, solved with single-crystal X-ray diffraction at T = 110 K, is found to be tetragonal, space group I4/m, with a = 10.

Thiophene-fused borepins as directly functionalizable boron-containing π-electron systems.

Synthetic protocols were developed for the gram-scale preparation of two isomeric dithienoborepins (DTBs), boron-containing polycyclic aromatics featuring the fusion of borepin and thiophene rings. DTBs exhibit reversible cathodic electrochemistry and boron-centered Lewis acidity in addition to enhanced electronic delocalization relative to benzo-fused analogues. Boron's precise position within the conjugation pathway of DTBs significantly affected electronic structure, most clearly demonstrated by the variation in spectroscopic responses of each isomer to fluoride ion binding.

Ethical issues in surgical innovation.

Innovation is responsible for most advances in the field of surgery. Innovative approaches to solving clinical problems have significantly decreased morbidity and mortality for many surgical procedures, and have led to improved patient outcomes. While innovation is motivated by the surgeon's expectation that the new approach will be beneficial to patients, not all innovations are successful or result in improved patient care.

Thioether-ligated iron(II) and iron(III)-hydroperoxo/alkylperoxo complexes with an H-bond donor in the second coordination sphere.

The non-heme iron complexes, [Fe(II)(N3PySR)(CH3CN)](BF4)2 () and [Fe(II)(N3Py(amide)SR)](BF4)2 (), afford rare examples of metastable Fe(iii)-OOH and Fe(iii)-OOtBu complexes containing equatorial thioether ligands and a single H-bond donor in the second coordination sphere. These peroxo complexes were characterized by a range of spectroscopic methods and density functional theory studies. The influence of a thioether ligand and of one H-bond donor on the stability and spectroscopic properties of these complexes was investigated.