Vitamin C Supplementation and Athletic Performance: A Review.

Many athletes utilize high-dose vitamin C supplementation to optimize athletic performance. A review of research over the past 10 years on the use of vitamin C and athletic performance show mixed results. Fourteen randomized control trials were reviewed.

Metal-Support Interactions in Molecular Single-Site Cluster Catalysts.

This study provides atomistic insights into the interface between a single-site catalyst and a transition metal chalcogenide support and reveals that peak catalytic activity occurs when edge/support redox cooperativity is maximized. A molecular platform MCoSe(PEt)(L) (-M, M = Cr, Mn, Fe, Co, Cu, and Zn) was designed in which the active site (M)/support (CoSe) interactions are interrogated by systematically probing the electronic and structural changes that occur as the identity of the metal varies. All 3d transition metal -M clusters display remarkable catalytic activity for coupling tosyl azide and -butyl isocyanide, with Mn and Co derivatives showing the fastest turnover in the series.

Redox-Switchable Allosteric Effects in Molecular Clusters.

We demonstrate that allosteric effects and redox state changes can be harnessed to create a switch that selectively and reversibly regulates the coordination chemistry of a single site on the surface of a molecular cluster. This redox-switchable allostery is employed as a guiding force to assemble the molecular clusters ZnCoSeL' (L' = PhPN(H)Tol, Ph = phenyl, Tol = 4-tolyl) into materials of predetermined dimensionality (1- or 2-D) and to encode them with emissive properties. This work paves the path to program the assembly and function of inorganic clusters into stimuli-responsive, atomically precise materials.

Phase-averaged and cycle-to-cycle analysis of jet dynamics in a scaled up vocal-fold model.

Phase-averaged and cycle-to-cycle analysis of key contributors to sound production in phonation is examined in a scaled-up vocal-fold model. Simultaneous temporally and spatially resolved pressure and velocity measurements permitted examination of each term in the streamwise integral momentum equation. The relative sizes of these terms were used to address the issue of whether transglottal pressure is a surrogate for vocal-fold drag, a quantity directly related to sound production.

Increasing reactivity by incorporating π-acceptor ligands into coordinatively unsaturated thiolate-ligated iron(II) complexes.

Reported herein is the structural, spectroscopic, redox, and reactivity properties of a series of iron complexes containing both a π-donating thiolate, and π-accepting -heterocycles in the coordination sphere, in which we systematically vary the substituents on the -heterocycle, the size of the -heterocycle, and the linker between the imine nitrogen and tertiary amine nitrogen. In contrast to our primary amine/thiolate-ligated Fe(II) complex, [Fe(SN(tren))] (), the Fe(II) complexes reported herein are intensely colored, allowing us to visually monitor reactivity. Ferrous complexes with R = H substituents in the 6-position of the pyridines, [Fe(SN(6-H-DPPN)] () and [Fe(SN(6-H-DPEN))(MeOH)] () are shown to readily bind neutral ligands, and all of the Fe(II) complexes are shown to bind anionic ligands regardless of steric congestion.

Robust Synthetic Route toward Anisotropic Metal-Organic Cages with Tunable Surface Chemistry.

Metal-organic cages with well-defined interior cavities and tunable surface chemistry serve as attractive building blocks for new types of soft nanoporous materials. While a compositionally diverse repertoire of metal-organic cages exists, the vast majority feature highly symmetric cores. Here, we report a robust, generalizable synthetic route toward anisotropic copper paddlewheel-based cages with tunable pendant amide groups.

CO Hydrogenation Catalyzed by a Ruthenium Protic N-Heterocyclic Carbene Complex.

We describe the hydrogenation of CO to formate catalyzed by a Ru(II) bis(protic N-heterocyclic carbene, p-NHC) phosphine complex [Ru(bpy)(MeCN)(P(p-NHC))](PF) (). Under catalytic conditions (20 μmol catalyst, 20 bar CO, 60 bar H, 5 mL THF, 140 °C, 16 h), the activity of is limited only by the amount of KPO present in the reaction, yielding a nearly 1:1 ratio of turnover number (TON) to equivalents of KPO (relative to ), with the highest TON = 8040. Additionally, analysis of the reaction solution post-run reveals the catalyst intact with no free ligand observed.

Atomically Defined Nanopropeller FeCoSe(PhPNTol): Functional Model for the Electronic Metal-Support Interaction Effect and High Catalytic Activity for Carbodiimide Formation.

Atomically defined interfaces that maximize the density of active sites and harness the electronic metal-support interaction are desirable to facilitate challenging multielectron transformations, but their synthesis remains a considerable challenge. We report the rational synthesis of the atomically defined metal chalcogenide nanopropeller FeCoSeL (L = PhPNTol) featuring three Fe edge sites, and its ensuing catalytic activity for carbodiimide formation. The complex interaction between the Fe edges and CoSe support, including the interplay between oxidation state, substrate coordination, and metal-support interaction, is probed in detail using chemical and electrochemical methods, extensive single crystal X-ray diffraction, and electronic absorption and Mössbauer spectroscopy.

Long-Lived Intermediates in a Cooperative Two-State Folding Transition.

Biomolecular folding often occurs through a cooperative two-state reactant ↔ product transition; the term cooperative does not convey that intermediate structures are nonexistent but rather that these states are not observable by existing experimental techniques. Because of this, few intermediates have been studied and characterized. Recently, ion mobility spectrometry (IMS) measurements revealed that the oligomer polyproline-13 (Pro13, which in propanol (PrOH) favors the right-handed helical PPI structure having adjacent pyrrolidine rings in a cis configuration) folds through six sequential long-lived intermediates as it converts to the all-trans-configured PPII structure that is favored in aqueous solutions.

Employing Forbidden Transitions as Qubits in a Nuclear Spin-Free Chromium Complex.

The implementation of quantum computation (QC) would revolutionize scientific fields ranging from encryption to quantum simulation. One intuitive candidate for the smallest unit of a quantum computer, a qubit, is electronic spin. A prominent proposal for QC relies on high-spin magnetic molecules, where multiple transitions between the many MS levels are employed as qubits.

A mononuclear transition metal single-molecule magnet in a nuclear spin-free ligand environment.

The high-spin pseudotetrahedral complex [Co(C3S5)2](2-) exhibits slow magnetic relaxation in the absence of an applied dc magnetic field, one of a small number of mononuclear complexes to display this property. Fits to low-temperature magnetization data indicate that this single-molecule magnet possesses a very large and negative axial zero-field splitting and small rhombicity. The presence of single-molecule magnet behavior in a zero-nuclear spin ligand field offers the opportunity to investigate the potential for this molecule to be a qubit, the smallest unit of a quantum information processing (QIP) system.