Publications

The synthesis of discrete, cationic binuclear μ-aryl dicopper complexes [Cu2(μ-η(1):η(1)-Ar)DPFN]X (Ar = C6H5, 3,5-(CF3)2C6H3, and C6F5; DPFN = 2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine; X = BAr4(-) and NTf2(-); Tf = SO2CF3) was achieved by treatment of a dicopper complex [Cu2(μ-η(1):η(1)-NCCH3)DPFN]X2 (X = PF6(-) and NTf2(-)) with tetraarylborates. Structural characterization revealed symmetrically bridging aryl groups, and (1)H NMR spectroscopy evidenced the same structure in solution at 24 °C. Electrochemical investigation of the resulting arylcopper complexes uncovered reversible redox events that led to the synthesis and isolation of a rare mixed-valence organocopper complex [Cu2(μ-η(1):η(1)-Ph)DPFN](NTf2)2 in high yield. The solid-state structure of the mixed-valence μ-phenyl complex exhibits inequivalent copper centers, despite a short Cu···Cu distance. Electronic and variable-temperature electron paramagnetic resonance spectroscopy of the mixed-valence μ-phenyl complex suggest that the degree of spin localization is temperature-dependent, with a high degree of spin localization observed at lower temperatures. Electronic structure calculations agree with the experimental results and suggest that the spin is localized almost entirely on one metal center.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The results of chemical composition and pretreatment on Mg-Al hydrotalcites and alumina-supported MgO were evaluated for the gas-phase, self-condensation reaction of C<sub>3</sub>-C<sub>5</sub> biomass-derived methyl ketones. We demonstrate that the selectivity toward the acyclic dimer enone and the cyclic enone trimer can be tuned by controlling the temperature of hydrotalcite calcination. Methyl ketone cyclization is promoted by Lewis acidic sites present on the hydrotalcite catalysts. XRD and thermal decomposition analysis reveal that the formation of periclase MgO starts above 623 K accompanied by complete disappearance of the hydrotalcite structure and is accompanied by an increase in hydroxyl condensation as the formation of well-crystallized periclase. <sup>27</sup>Al MQMAS and <sup>25</sup>Mg MAS NMR show that at progressively higher temperatures, Al<sup>3+</sup> cations diffuses out of the octahedral brucite layers and incorporate into the tetrahedral and octahedral sites of the MgO matrix thereby creating defects to compensate the excess positive charge generated. The oxygen anions adjacent to the Mg<sup>2+</sup>/Al<sup>3+</sup> defects become coordinatively unsaturated, leading to the formation of new basic sites. A kinetic isotope effect, <em>k</em><sub>H</sub>/<em>k</em><sub>D</sub>= 0.96, is observed at 473 K for the reaction of (CH<sub>3</sub>)<sub>2</sub>CO versus (CD<sub>3</sub>)<sub>2</sub>CO, which suggests that carbon-carbon bond formation leading to the dimer aldol product is the rate-determining step in the condensation reaction of methyl ketones. Furthermore, we show that acid-base catalysts having similar reactivity and higher hydrothermal stability to that of calcined hydrotalcites can be achieved by creating defects in MgO crystallites supported alumina as a consequence of the diffusion of Al<sup>3+</sup> cations into MgO. The physical properties of these materials are shown to be very similar to those of hydrotalcite calcined at 823 K.

Abstract Background Different measures to assess muscle size - magnetic resonance (MR) derived thigh muscle volume and d3-creatine dilution derived muscle mass (D 3 Cr muscle mass) – may have similar associations with strength, power, physical performance, fitness, and functional limitations in older adults. Methods Men (N=345) and women (N=482) aged ≥70 years from the Study of Muscle, Mobility and Aging completed exams including leg extension strength (1-repetition max) and cardiopulmonary exercise testing to assess fitness (VO 2 peak). Correlations and adjusted regression models stratified by sex were used to assess the association between muscle size measures and study outcomes; we tested for sex interactions. Results D 3 Cr muscle mass and MR thigh muscle volume were correlated (men: r=0.62, women: r=0.51, p<.001). Lower D 3 Cr muscle mass and lower MR thigh muscle volume were associated with lower strength and lower VO 2 peak in both men and women; D 3 Cr muscle mass was more strongly associated with strength in men than in women (p-int<0.05). There were correlations, though less consistent, between muscle size or mass with physical performance and function. Associations between the muscle size measures and the study outcomes occasionally varied by sex, and associations of MR thigh muscle volume were, at times, slightly more strongly associated with the study outcomes than was D 3 Cr muscle mass. Conclusions Less muscle –measured by either D 3 Cr muscle mass or MR thigh muscle volume - was associated with lower strength and worse performance. Varied associations by sex and assessment method suggest consideration be given to which measurement to use in future studies.

Lithium phosphorus oxynitride, also known as Lipon, solid-state electrolytes are at the center of the search for solid-state Li metal batteries. Key to the performance of Lipon is a combination of high Li content, amorphous character, and the incorporation of N into the structure. Despite the material's importance, our work presents the first study to fully resolve the structure of Lipon using a combination of ab initio molecular dynamics, density functional theory, neutron scattering, and infrared spectroscopy. The modeled and experimental results have exceptional agreement in both neutron pair distribution function and infrared spectroscopy. Building on this synergy, the structural models show that N forms both bridges between two phosphate units and nonbridging apical N. We further show that as the Li content is increased the ratio of bridging to apical N shifts from being predominantly bridging at Li contents around 2.5:1 Li:P to only apical N at higher Li contents of 3.38:1 Li:P. This crossover from bridging to apical N appears to directly correlate with and explain both the increase in ionic conductivity with the incorporation of N and the ionic conductivity trends found in the literature.

Abstract Here, we report on the Quaternary Volsci Volcanic Field (VVF, central Italy). In light of new 40 Ar/ 39 Ar geochronological data and compositional characterization of juvenile eruptive products, we refine the history of VVF activity, and outline the implications on the pre-eruptive magma system and the continental subduction processes involved. Different from the nearby volcanic districts of the Roman and Campanian Provinces, the VVF was characterized by small-volume (0.01–0.1 km 3 ) eruptions from a network of monogenetic centers (mostly tuff rings and scoria cones, with subordinate lava occurrences), clustered along high-angle faults of lithospheric depth. Leucite-bearing, high-K (HKS) magmas (for which we report for the first time the phlogopite phenocryst compositions) mostly fed the early phase of activity (∼761–539 ka), then primitive, plagioclase-bearing (KS) magmas appeared during the climactic phase (∼424–349 ka), partially overlapping with HKS ones, and then prevailed during the late phase of activity (∼300–231 ka). The fast ascent of primitive magma batches is typical of a tectonically controlled volcanic field, where the very low magma flux is a passive byproduct of regional tectonic strain. We suggest that the dominant compressive stress field acting at depth was accompanied by an extensional regime in the upper crust, associated with the gravity spreading of the Apennine chain, allowing the fast ascent of magma from the mantle source with limited stationing in shallow reservoirs.