Synthetic polymeric antioxidants are promising building blocks for thin films that demonstrate excellent adhesive and antioxidant properties as well as facile control over the degree of material hydrophobicity. Here, we studied the efficiency of antioxidant polymers as anticorrosion agents, based on their ability to reduce oxygen, which is one of the triggers of corrosion. Polymers containing a polyphenol repeating unit, either 3,4-dihydroxybenzyl methacrylamide or 3,4,5-trihydroxybenzyl methacrylamide, as well as a hydrophobic repeating unit, hexyl methacrylamide, were studied as thin solution-cast polymer films. These films were deposited from tetrahydrofuran solutions onto a metal substrate, such as aluminum and steel, and annealed at 85°C for 2 hours. The resulting micron-thick films were transparent. Studies using the potentiodynamic polarization technique revealed that the antioxidant polymers acted as corrosion inhibitors showing better passivation and lower corrosion current densities in comparison with bare aluminum substrates or films of a control polymer which lacked antioxidant groups. Moreover, polymer films on aluminum substrates exhibited superior impedance characteristics in comparison with bare substrates as measured by electrochemical impedance spectroscopy after 4 hours of immersion in 0.001 M NaCl. The superior performance of the antioxidant polymer films is attributed to the dual effect of formation of a protective barrier due to chemical crosslinking of antioxidant polymers, as well as to direct reactions of synthetic polyphenols with oxygen. The effect of the chemistry of polyphenol rings on the anticorrosion performance will be discussed.

Antioxidant polymer coatings for corrosion protection of metal substrates

This study investigates physical and chemical sorption mechanisms of U and As onto natural limestone by integrating laboratory experiments, aqueous chemistry, microscopy, and spectroscopy. Recent studies found elevated concentrations of U and As in water sources affected by mining, posing potential health hazards to Native American communities. Limited research has evaluated sorption of co-occurring U and As using naturally occurring materials such as limestone which is abundant in the Southwestern US. Initial experiments assessed the reactivity of 1 mM of As and U with soluble CO32- and Ca2+at pH 3 and 7. Changes on the concentration of U and As depended on the pH, presence of CO32- and Ca2+, and interaction between U and As. Main findings showed that at pH 3, As and U concentration decreased to &lt;0.15 mM when both metals were present in the system. At pH 7, the presence of CO32- limited the reactivity of U and As. Soluble U and As concentration decreased to &lt;0.05 mM - when both metals were present in the system in absence of CO32-. Nevertheless, CO32- increased their solubility to ≈0.45 mM. Future experiments will also evaluate the reactivity of low concentrations U and As in presence of soluble CO32-and Ca2+, sorption of U and As using natural limestone, and conduct synchrotron-based spectroscopy analyses to identify solid chemical changes. Results from this study indicate that the dissolution of Ca2+ and CO32- from limestone and the co-precipitation U with As affect metal solubility. These findings have relevant implications for site remediation.

Physical and chemical mechanisms of uranium (U) and arsenic (As) sorption onto limestone

The solid solution Eu(Ga1-xAlx)4 was grown in single crystal form to reveal a rich variety of crystallographic, magnetic, and electronic properties that differ remarkably from the isostructural end compounds EuGa4 and EuAl4. This is surprising given the similar covalent radii and electronic configuration of Ga and Al. Here we report the onset of magnetic spin reorientations and metamagnetic transitions observed in compounds from x = 0 - 1 evidenced by magnetization and temperature-dependent specific heat measurements. A maximum TN ~ 20 K is reported for x = 0.49, which is explained by the concomitant contraction of the a lattice parameter in this composition. Interestingly, anomalies in temperature-dependent resistivity measurements consistent with charge density wave behavior is shown for x = 0.49 and 1 only. Density functional theory calculations were used to show the increased ionic character between the Ga-Al bonds in the x = 0.49 structure, and crystallographic origins of the charge density wave behavior including disorder and chemical pressure are proposed.

Interplay between charge density wave behavior and antiferromagnetic order in the intermetallic single crystal system Eu(Ga1-xAlx)4

Chemist with disabilities are people with unique abilities and a different perspective.  In this presentation we will present an outreach program that shows students famous chemist who had disabilites.

Celebrating a diversity, giving chemist a unique perspective

In the pharmaceutical industry, an organic chemist must be adaptable to consistently fulfill development needs as a project advances from an early stage to selection of a compound for first-in-human clinical trials. Early in the research phase, value is added by developing library-amenable methods to open up new design space. As advanced lead matter is discovered, a synthetic chemists’ role changes to development of novel, yet practical syntheses of key compounds and intermediates that translate to larger scales to allow important clinical questions to be addressed. Case studies drawing from several drug discovery programs at Pfizer will be discussed including the decision-making that went into the selection of routes for Acetyl CoA-Carboxylase (ACC) Inhibitors, Ketohexokinase (KHK) inhibitors, and Adenosine Monophosphate-activated Protein Kinase (AMPK) Activators.

Speed to clinic: The critical role of organic synthesis in medicinal chemistry

Surface modification of materials is important to achieve desired physical and chemical properties such as hydrophobicity and pH and is extremely important in applications such as dyeing performance of textiles, and antifouling or self-cleaning materials. Efficient and selective modification of such properties on a material surface is challenging, however, and can involve the use of expensive chemicals with negative impacts on the environment. Herein, we quantify the photochemistry of natural uronate containing polysaccharides in the presence of Iron (III) ions. We show that this reaction can occur in a variety of natural materials, and use the photochemical reaction between Fe(III) and carboxylates to alter the physical and chemical properties of materials such as cotton fabric and hydrogels. Specifically, the photochemistry of the Fe (III)-uronate system generates radical species during the reaction. By taking the advantage of this radical species generation, we modify the surface properties of selected polyuronate containing substrates with different acrylic monomers. The manipulation of the desired chemical and physical properties of the substrate is based on the choice of acrylate. This strategy provides a simple approach to design materials with different surface properties by using much cheaper naturally derived materials.

Harnessing Fe (III) carboxylate photochemistry for surface modification on materials

A ‘Chemistry Science Investigation:Dognapping’ workshop (termed CSI:Dognapping) has been designed to: (i) target and inspire 3rd - 5th grade level students where they will view themselves as “Junior Scientists” before they enter middle school when career decisions are made, (ii) enable hands-on experience in fundamental scientific concepts, (iii) increase public interaction with science, technology, engineering, and mathematics personnel by providing face-to-face opportunities that cannot be achieved in a classroom, (iv) give teachers a pathway forward for scientific resources, (v) meet the New Mexico K–5 Science Benchmark Performance Standards, and (vi) most importantly, have FUN! Survey results (before, after, and longer) indicate that after attending the workshop, the information presented on several key scientific concepts is retained for up to 2 months. This workshop has been performed over 12 years and won a 2015 ChemLuminary Award for Outstanding Kids & Chemistry Program (Central New Mexico Local Section). This talk will describe the program in detail.

Chemistry science investigation: Dognapping. A workshop to inspire STEM students

Deep understanding of particularly in the surface behaviors of redox sensitive additives is important in further efficiency enhancement of capacitive deionization (CDI) technique. In this study, effect of surface ionization on the CDI efficiency of Fe, Co, and Ni doped α-MnO2 as a model system is studied. It was found that the CDI efficiency of dopedα-MnO2 increases with increasing positive surface charge, which is realized as a result of reduced chloride electroadsorption capacity when surface is negatively charged. This further accounts the observations that the CDI efficiency increases with increasing pKa1 and pKa2 of doped α-MnO2 as a low degree of surface ionization is in favor of CDI efficiency. Moreover, reduced structural stress induced by doped elements is noted to possess higher pKa1 and pKa2, suggesting that adjusting the structural stress of α-MnO2 would be a promising strategy in further CDI efficiency enhancement.

Correlation between the degree of surface ionization and the capacitive deionization efficiency of doped MnO2 electrodes

Direct layer-by-layer (LbL) assembly of cationic, small-molecule antibacterial bioactives with water-soluble, ionic polyphosphazenes (PPzs) containing trifluoroethoxy and carboxyl substitients is reported. First, influence of PPzs hydrophobicity and antibiotic charge density on LbL assembly was studied via evolution of dry film thickness. We found that the use of fluorinated PPz polyelectrolytes enhanced ionic pairing within LbL coatings, and that increasing charge density of small molecules increased antibiotic uptake. This strategy was successful even in the case of gentamicin, a hydrophilic, small antibiotic with only 3 to 4 positive charges at pH 7.5. Confirmation of antibiotic presence in films was demonstrated via x-ray photoelectron spectroscopy. Importantly, LbL films of fluorinated PPz polyelectrolytes retained antibiotics in physiological conditions due to the enhanced hydrophobic interactions. In contrast, LbL films of non-fluorinated PPzs released antibiotics at low pH and in the presence of salt following the charge renormalization argument. The potential of these coatings with a biomedically relevant bacterial strain, Staphylococcus aureus, is discussed.

Trapping of antibacterial agents within hydrophobic films of polyphosphazene polyelectrolytes

Time-resolved x-ray tools allow measuring electronic and geometric structure changes. X-Ray emission spectroscopy is sensitive to electronic changes, such as oxidation and spin states, while x-ray absorption fine structure tools deliver information about the local geometric structure around the selected absorbing atom. Combining these tools with forward scattering in one single setup allows to extract simultaneous information about the local to rather global structural changes occurring in the reacting system. We will present some case examples, for which pico- and femtosecond x-ray experiments deliver new insight into evolving dynamic processes, including reactive high-valent iron compounds and a class of spin transition systems. This will be preceded by an introduction about the information content of x-ray tools. Finally, all these tools can be combined into one single experimental setup, and the Femtosecond X-Ray Experiments (FXE) Instrument at European XFEL will allow just this, and its operation just started in late Summer 2017. We will present the current status of this new instrument at European XFEL [1] together with some early results.

Femtosecond X-ray experiments: New observables for chemical dynamics studies

Outreach summer camps, particularly those focused on increasing the number of women in STEM, are commonplace. Material science focused camps are popular due to the widespread applications associated with the field and their connection to fundamental fields students are exposed to in high school, such as chemistry. Unfortunately, because of this large scope, camps are often forced to pick and choose what topics are covered. This lack of cohesion within the camp content can lead to participant confusion, which could be misinterpreted as a fundamental lack of engineering understanding or ability. Because of this, we have implemented a weeklong summer camp curriculum composed of a design project and 14 separate topics together using an overarching paradigm as a framework. While this restructuring on the surface looks promising, very little has been determined regarding the effect curriculum has on participants’ opinion of STEM after camp. To understand the connection between outreach curriculum and STEM self-confidence among high school women, we studied outreach camps that varied in how design was incorporated into their structure. We chose to study a design-focused camp, a design-absent camp, and a design-incorporated camp (run by the authors). Initial results from pre-post surveys with the participants indicate that design-incorporated camp increased the participants’ desire to be an engineer while design-absent camp decreased their participants’ desire to be an engineer. Similar opposing trends were observed for the participants’ perception that engineering is interesting and their desire to apply to engineering programs in college. All three changes were statistically significant. With these results, we hope to continue this study to gather more insight and improve the overall understanding of outreach curriculums and its effect on STEM perceptions.

Investigating the effect of curriculum on gender-minority STEM outreach camp outcomes

A quantum material is loosely defined as a material in which there are one or more highly correlated microscopic degrees of freedom that give rise to emergent behavior – actions that appear greater than the sum of the individual interactions. In this talk, I will discuss the current status of the field and present possible future visions for the discovery of new quantum materials, with a particular focus on the potential for synergistic advances across synthesis, characterization, theory, computation, and data collection and analysis. The importance of understanding and harnessing individual chemical steps to create tailored structures across different lengthscales will be highlighted. What are the prospects for systematic making and breaking of individual bonds in the solid state? What emergent phenomena – at the electron, atomic, or molecular scale – can we discover and harness? Particular attention will be put on the recent advancements in the discovery and synthesis of an exotic class of materials known as quantum spin liquids.

The dawn of the chemistry of quantum materials: Discovery, synthesis, and behavioral insights

The utilization of wood-derived building blocks (xylochemicals) and other abundantly available, non-food biomasses to replace fossil-based precursors is an attractive research subject in modern polymer science and engineering. The continuing development of economically viable bio-based feedstocks and subsequent, new platform chemicals opens opportunities to increase the resource base from which chemical and materials engineers can draw to meet specific polymer and composite property requirements. Recently, significant efforts have transpired to obtain bio-based polymers and composites with enhanced thermal and physical properties for a wide variety of applications, from packaging to coatings to adhesives to energy storage devices. In continuing these efforts and to push the envelope, we have strategically assembled xylochemicals via our molecularly hybrid approach and have prepared and examined a variety of bio-based thermoplastics, thermosets, and composites, including epoxies, vinyl esters, allyl ethers, polyesters, and polycarbonates, all focused for utility in military applications. These novel materials are largely based on lignin-derived, (hemi)cellulose-derived, and cashew nut shell liquid-derived platform chemicals, but also contain components sourced from alternative bio-based feedstocks such as birch bark and agriculture wastes. This presentation will highlight our work on fundamentally understanding the processing-structure-property-toxicity relationships of our bio-based polymers and composites via thermal analysis and mechanical testing techniques. Furthermore, their utilities in military applications will be discussed.

Advancement of bio-based polymers and composites for military applications: Pushing the envelope via strategic assemblies of xylochemicals

In this talk, I will present an update on our explorations of the use of high fluid pressure (up to 300 atm), high temperature (2500+ C) conditions in an optical floating zone furnace for materials discovery and crystal growth. Particular emphasis will be placed on the interplay between the solvent-like behavior, the tuning of chemical potential, and the enhancing of reactivity to drive the formation and stabilization of new materials. An outlook for the future of the technique, and the technical challenges that must be overcome, will also be presented.

Inorganic materials discovery and crystal growth in supercritical fluids

Vinyl ester resins (VERs) are used to create polymers with a variety of favorable properties ideal for high performance applications. Commercially available VERs contain derivates of bisphenol A (BPA), a known human endocrine disruptor. Therefore, bio-based alternatives are being investigated for their sustainability aspect and possibilities of reduced toxicities and improved environmentally benign characteristics. Vanillin, a lignin aromatic derivative, can be reduced to vanillyl alcohol and is considered a viable platform chemical for the production of bisphenols. Cardanol, a main component of cashew nutshell liquid (CNSL), is an aromatic, non-edible by-product of cashew harvesting. With a long, C15 alkyl chain, cardanol has been shown to impart toughness and thermal resistant properties to polymers and composites. Vanillyl alcohol and cardanol (VAC) were coupled to create a bio-based bisphenol and its hydrogenated form (VAHC). From these bisphenols, VE monomers were synthesized, blended with a reactive diluent and cured. Polymers containing VAC and VAHC were shown to be viable bisphenols with increased thermal stabilities yet decreased glass transition temperatures due to the inherent C15 alkyl chain cardanol. The toughness of the polymers containing VAC and VAHC were greater than a polymer containing a structurally similar cross-linking agent (dimethacrylated BPA), however, less than a commercially available cured VER. Nonetheless, we present this next generation bisphenols derived from renewables as our fundamental processing-structure-property relationship study demonstrates their utility in thermosetting resin applications.

Next generation bisphenols derived from lignin and cashew nut shell liquid (CNSL): Application in thermosetting resins

Due to the increased environmental threat from CO2 emission, efficient and selective conversion of CO2 to useful chemicals and fuels has received considerable attention. Developing new nanocatalysts is an attractive solution. Of various catalysts explored to date, gold (Au) is the most promising one to convert CO2 to CO in an aqueous-phase electrochemical reduction. However, ultrasmall Au nanocatalysts (AuNCs, &lt; 2 nm) have proven to be more favorable for water reduction over CO2, although they possess a large surface-to-volume ratio providing abundant active sites. We report that ultrasmall AuNCs (1.9 ± 0.3 nm) supported on nitrided carbon showed remarkable activity and selectivity for CO2 reduction. At 0.7 V, the mass activity reaches &gt; 1000 A g-1 with a Faradaic efficiency for CO of ~80 %, that is an order of magnitude more active than the state-of-the-art results. The cooperative effect of Au and the nitride carbon support is essential for the high activity and selectivity of ultrasmall AuNCs. X-ray photoelectron spectroscopy (XPS) shows an electron rich surface of AuNCs on nitrided carbon, compared to the ones after quenching N sites. Thermogravimetric analysis/mass spectrometry (TGA-MS) confirms that the nitrided carbon has a stronger CO2 adsorption compared to the ones with quenched N sites. We expect that our results will illustrate an alternative way to effectively lower the cost of Au catalyst per unit weight of the product while maintaining the high selectivity for CO2 reduction.

Superiorly active and selective Au nanocatalysts supported on nitrided carbon for electrocatalytic CO2 reduction

The Hard X-ray Nanoprobe Beamline (HXN) at the National Synchrotron Light Source II offers a suite of advanced imaging tools for visualizing morphology, chemistry, composition and crystalline strain with spatial resolutions at 5 to 50 nanometers.  Though these resolutions are still rather modest in comparison with electron microscopy techniques (SEM, TEM, or sTEM), the deep penetrating power of x-rays offers the capability of visualizing deeply buried nanostructures with minimal sample preparation.   A unique capability of the HXN Beamline is that all experiments are carried out using multimodal imaging, where two or more different imaging measurements are performed simultaneously, so that different types of sample heterogeneity (i.e. morphology, composition, crystalline ordering) can be visualized together.   The presentation will focus on two common types of applications.  The first application is visualization of elemental distribution together with nanostructure.  This method is an effective way of characterizing material synthesis or investigating phase separation.  For battery materials, elemental mapping investigation can be performed under in-situ electrochemical control.   The second application is to visualize strain distribution within a single crystal sample.  This method allow investigating crystalline defects associated with synthesis.  The presentation will provide a few science examples for both categories of applications.

Material characterizations by nanoscale X-ray imaging

The utilization of wood-derived building blocks (xylochemicals) and other abundantly available, non-food biomasses to replace fossil-based precursors is an attractive research subject in modern polymer science and engineering. The continuing development of economically viable bio-based feedstocks and subsequent, new platform chemicals opens opportunities to increase the resource base from which chemical and materials engineers can draw to meet specific polymer and composite property requirements. Recently, significant efforts have transpired to obtain bio-based polymers and composites with enhanced thermomechanical properties for a wide variety of applications. In continuing these efforts, we have prepared and examined a variety of bio-based thermoplastics, thermosets, and composites, including epoxies, vinyl esters, allyl ethers, polyesters, and polycarbonates. These novel materials were strategically assembled from monomers based on lignin-derived, (hemi)cellulose-derived, and cashew nut shell liquid-derived platform chemicals. This presentation will highlight our work on fundamentally understanding the processing-structure-property relationships of our bio-based polymers and composites via thermal analysis techniques. Additionally, their utilities in military, civilian, and medical applications will be discussed.

Strategic assemblies of wood-derived building blocks for the advancement of bio-based polymers and composites

Dysregulation of lipid metabolism is implicated in diabetes mellitus and cardiovascular disease. High-density lipoproteins (HDL), which remove excess cholesterol from cells, form a heterogeneous population of mature spherical and nascent discoidal particles 8-12 nm in diameter. Mature HDL contains a core of apolar lipids (cholesterol esters, triacylglycerol) and a surface of polar lipids (phospholipids, cholesterol) stabilized by apolipoproteins, mainly apoA-I and apoA-II. ApoA-I provides a structural scaffold and a functional ligand on the particle surface, and apoA-II modulates HDL structure-function and stability. We have probed the structural and compositional changes in HDL upon the onset of diabetes. Our goal is to test a hypothesis that increased triglyceride content decreases structural stability of plasma HDL. Blood samples were collected from cohorts of patients who were normolipidemic and normoglycemic (NL-HDL), diabetic with good glycemic control due to medication (GC-HDL), and newly diagnosed diabetic with poor glycemic control (PC-HDL). Lipoproteins were studied for biochemical composition, structure and stability by using circular dichroism spectroscopy, SDS, native gel electrophoresis, Western blotting, and negative staining electron microscopy. MALDI-TOF mass spectrometry shows the absence of post-translational modifications in all major apolipoproteins. Irrespective of the cohort, there is an inverse correlation between increased triglyceride content and lipoprotein stability. However, changes in HDL triglycerides associated with diabetes are not large enough to affect HDL stability. The results also suggest an increased degradation rate of HDL proteins in the PC-HDL group when compared to GC-HDL or NL-HDL, which is currently under investigation.

Structural remodeling of high-density lipoproteins in patients with diabetes mellitus

Ultrafast X-ray spectroscopy (XAS) allows visualizing transient electronic and geometric changes accompanying a sequence of redox reactions occurring during molecular catalysis. We have used it to study a high-valent Fe complex, containing the metal in an unusually high oxidation state (+V), which belongs to a class of compounds considered as model systems of vital reaction intermediates found in several important biocatalytic reactions. However, octahedral Fe+V complexes have not yet been detected for biologically relevant conditions (room-temperature solutions). Only recently picosecond IR studies of Fe+V formation, following UV photodetachment of N2 from the azido-iron(III) complex in CH3CN solution, extracted a subsequent formation of the high-valent complex on a 10 ps time scale. The photochemical reaction cycle of the parent complex 1 involves competing reaction pathways throughout the UV-VIS range with the two most relevant reaction products 2 and 3 (Fig. 1a). Here we employed ultrafast XAS to study the photoinduced dynamics of both long-lived photoproducts and ultrafast reaction intermediates, which may involve changes in the electronic and geometric structures of the molecule. For this purpose we carried out a combined study following photoexcitation across UV and VIS ranges and using both 100 ps hard X-ray pulses from a synchrotron (Figs 1b and 1c) and furthermore fs X-ray from an X-ray Free Electron Laser. Time-resolved XAS with both ps and fs temporal resolution helped to identify key steps during this light-triggered reaction. Oxidation state changes together with the local environment around the Fe atom were extracted via the XANES, since it is sensitive to chemical shifts via the so-called pre-edge resonance transitions, whereas X-ray emission spectroscopy allowed for further identifying the spin states of the involved intermediate excited states.

Ultrafast X-ray spectroscopy of transition metal compounds relevant for catalysis: a study case of a high-valent Fe complex

Dielectrophoresis (DEP) is good for manipulation of large particles like cells, since DEP force is proportional to the cube of particle size. While for small particles such as proteins, a super high electric field gradient is needed. In this work, core/shell nanorods (NDs) have been integrated into a DEP device to create the required gradient. Proteins can be concentrated at the designed spot and thus favor the protein detection. Firstly, micro-sawtooth electrodes are pre-patterned on glass substrate (a) and then three-dimensional oxide coated Ag NDs are fabricated, as shown in the cross-sectional view of the device diagram (b). A theoretical simulation has revealed that the thin oxide coating on Ag NDs, indicated by left panel of (c), creates a gradient of the electric field intensity squared as high as of 2.6×1024 V2/m3 (right panel of (c)). The above core/shell NDs based DEP device has enriched bovine serum albumin (BSA) proteins by 1800-fold when only applying 5 V electric potential. Image (d) shows fluorescent images of BSA concentration in the DEP devices integrated with/without NDs. Further, the detection of prostate-specific antigen (PSA), a cancer biomarker for diagnosis of prostate cancer after radical prostatectomy, has been performed. Briefly, specific antibodies are immobilized onto NDs, then PSA are concentrated and captured, and finally the signal from fluorescence labeled antibodies is detected. The limit of detection is measured as low as 2.6 pg/mL (e). In summary, this core/shell NDs based DEP platform poses great potentials in applications for early point-of-care diagnostics.

Core/shell nanorods based dielectrophoresis for biomarker concentration and detection

It is important to find environmentally-friendly replacements for chromate conversion coatings (CCCs) that are effective anticorrosion layers. In this work, high corrosion resistance is demonstrated with ultrathin (and transparent) multilayer coatings deposited on an aluminum alloy. Cationic waterborne polyurethane (PU) and anionic vermiculite clay (VMT) multilayer films were deposited layer-by-layer and compared with polyethleneimine (PEI)/VMT multilayers on aluminum. The combination of relatively hydrophobic polyurethane and highly aligned clay platelets leads to better barrier properties for the PU/VMT coating in an aqueous environment. A 30 bilayer PU/VMT coating, with a thickness of only 300 nm, provides two orders of magnitude improvement in impedance and imparts corrosion protection for five days, which is comparable to other composite coatings that are two orders of magnitude thicker. Another advantage of this unique coating system is that no surface treatments are required prior to coating due to the strong adhesion of polyelectrolytes to the metal. The environmental-friendliness, ease of production and excellent corrosion resistance make these LbL-assembled PU/VMT coatings a potential replacement for undesirable chromate conversion coatings.

Ultrathin nanobrick wall anticorrosion coatings

A class of hard materials incorporating borides of transition metals are easily cut yet rival diamond in terms of hardness. In the solids of the three borides: ReB2, TiB2 and OsB2, the boron sublattice is a chair, is planar, and is a boat, respectively. The anion ReB2- has three competing configurations involving the B-B bonding, in contrast to TiB2- and OsB2- which only have one configuration. This led to the determination that the promiscuity of the metal-boron bonds is linked to the ultrahard nature of ReB2. The combined anion photoelectron spectroscopic and theoretical study was able to show that ReB2 is, in fact, an ultrahard boride with promiscuous metal-boron bonding, while TiB2 lacks this promiscuity and is thus only superhard; this model was extended to OsB2 and concludes that it is also superhard.

Hardness of transition metal boride materials

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.