Unlocking the Photoluminescence and Photostability of Au Clusters through Pt-Mediated Band-Gap Engineering.

Au nanoclusters often demonstrate useful optical properties such as visible/near-infrared photoluminescence, in addition to remarkable thermodynamic stability owing to their superatomic behavior. The smallest of the 8e superatomic Au nanoclusters, Au, has limited applications due to its lack of luminescence and relatively low stability. In this work, we investigate the introduction of a single Pt dopant to the center of a halide- and triphenylphosphine-ligated Au nanocluster, affording a cluster with a proposed molecular formula PtAu(PPh)Br.

An electrospray-active N-heterocyclic carbene ligand for real-time analysis of organometallic reactions.

A charge-tagged N-heterocyclic carbene (NHC) has been synthesized and its utility in allowing the dynamic behaviour of metal complexes to be monitored in real time using electrospray ionization mass spectrometry demonstrated. This compound was used to prepare different metal-NHC complexes, and the kinetic behaviour of complex formation and ligand exchange was monitored in real time through the use of pressurized sample infusion electrospray mass spectrometry (PSI-ESI-MS).

Tunability in Heterobimetallic Complexes Featuring an Acyclic "Tiara" Polyether Motif.

Both cyclic "crown" and acyclic "tiara" polyethers have been recognized as useful for the binding of metal cations and enabling the assembly of multimetallic complexes. However, the properties of heterobimetallic complexes built upon acyclic polyethers have received less attention than they deserve. Here, the synthesis and characterization of a family of eight redox-active heterobimetallic complexes that pair a nickel center with secondary redox-inactive cations (K, Na, Li, Sr, Ca, Zn, La, and Lu) bound in acyclic polyether "tiara" moieties are reported.

Activation and Functionalization of the Uranyl Ion by Electrochemical Reduction.

Interconversion of the oxidation states of uranium enables separations and reactivity schemes involving this element and contributes to technologies for recycling of spent nuclear fuels. The redox behaviors of uranium species impact these processes, but use of electrochemical methods to drive reactions of molecular uranium complexes and to obtain molecular insights into the outcomes of electrode-driven reactions has received far less attention than it deserves. Here, we show that electro-reduction of the uranyl ion (UO) can be used to promote stepwise functionalization of the typically unreactive oxo groups with exogenous triphenylborane (BPh) serving as a moderate electrophile, avoiding the conventional requirement for a chemical reductant.

A diazirine's central carbon is sp-hybridized, facilitating conjugation to dye molecules.

Diazirines are versatile carbene precursors that are extensively used in biological target identification experiments. However, their photo-activation wavelength ( 365 nm) precludes their use in living organisms. Here we show that a reconceptualization of the diazirine hybridization state leads to conjugation of the diazirine motif to longer-wavelength chromophores.

Extended Sulfo-Pillar[6]arenes ─ a New Host Family and Its Application in the Binding of Direct Oral Anticoagulants.

Herein, we report the synthesis of extended sulfo-pillar[6]arenes (), a new host class with a pedigree in salt tolerance and ultrahigh binding affinity toward multiple drug classes. The parent sulfo-pillar[6]arene is a high-affinity host with the potential to act as a supramolecular reversal agent. However, it lacks synthetic diversification of the core scaffold.

Redox properties of [Cp*Rh] complexes supported by mono-substituted 2,2'-bipyridyl ligands.

The redox properties of half-sandwich rhodium complexes supported by 2,2'-bipyridyl (bpy) ligands can be readily tuned by selection of an appropriately substituted derivative of bpy, but the influences of single substituents on the properties of such complexes are not well documented, as disubstituted bpy variants are much more common. Here, the synthesis, characterization, and redox properties of two new [Cp*Rh] complexes (where Cp* is η-1,2,3,4,5-pentamethylcyclopentadienyl) supported by the uncommon mono-substituted ligands 4-chloro-2,2'-bipyridyl (mcbpy) and 4-nitro-2,2'-bipyridyl (mnbpy) are reported. Single-crystal X-ray diffraction studies and related spectroscopic experiments confirm installation of the single substituents (-Cl and -NO, respectively) on the bipyridyl ligands; the precursor monosubstituted ligands were prepared a divergent route from unsubstituted bpy.

Enantiopure molecules form apparently racemic monolayers of chiral cyclic pentamers.

Ultra-high vacuum scanning tunneling microscopy (UHV-STM) was used to investigate two related molecules pulse-deposited onto Au(111) surfaces: indoline-2-carboxylic acid and proline (pyrrolidine-2-carboxylic acid). Indoline-2-carboxylic acid and proline form both dimers and -symmetric "pinwheel" pentamers. Enantiomerically pure -(-)-indoline-2-carboxylic acid and -proline were used, and the pentamer structures observed for both were chiral.

Formation of Uranyl Peroxide Compounds via Dissolution of Studtite, [(UO)(O)(HO)](HO), in Ionic Liquids.

Four uranyl peroxide compounds with novel structures were formed following the dissolution of studtite, [(UO)(O)(HO)](HO), in imidazolium-based ionic liquids. The compounds were characterized using single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Raman and infrared (IR) spectroscopy, and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The ionic liquids used in the experiments were 1-ethyl-3-methylimidazolium (EMIm) diethyl phosphate, EMIm ethyl sulfate, and EMIm acetate.

Conformational disorder in the crystal structure of methyl 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranoside (methyl β-chitobioside) methanol monosolvate.

Methyl 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranoside (methyl β-chitobioside), (IV), crystallizes from aqueous methanol at room temperature to give a structure (CHNO·CHOH) containing conformational disorder in the exocyclic hydroxymethyl group of one of its βGlcNAc residues. As observed in other X-ray structures of disaccharides containing β-(1→4) O-glycosidic linkages, inter-residue hydrogen bonding between O3H of the βGlcNAc bearing the OCH aglycone and O5 of the adjacent βGlcNAc is observed based on the 2.79 Å internuclear distance between the O atoms.

Mausolates: Large-Cavity Chelates with Potential as Delivery Vehicles in Nuclear Medicine.

A new type of diborate clathrochelate (cage) ligand featuring nine inwardly pointing nitrogen donors that form a large, rigid cavity, termed a mausolate, is presented. The cavity size and high denticity make this an attractive delivery vehicle for large radionuclides in nuclear medicine. Metal mausolate complexes are stable to air and water (neutral pH) and display extremely high thermal stability (>400 °C).

Metal-cation-induced shifts in thiolate redox and reduced sulfur speciation.

Sulfur-containing anions ( thiolates, polysulfides) readily exchange in solution, making control over their solution speciation and distribution challenging. Here, we demonstrate that different redox-inactive alkali, alkaline earth, and transition metals (Li, Na, K, Mg, Ca, Zn, and Cd) shift the equilibria of sulfur catenation or sulfur reduction/oxidation between thiolate, polysulfanide, and polysulfide anions in acetonitrile solution. The thermodynamic factors that govern these equilibria are examined by identification of intermediate metal thiolate and metal polysulfide species using a combination of NMR spectroscopy, electronic absorption spectroscopy, and mass spectrometry.

Mechanistic study of the atomic layer deposition of cobalt: a combined mass spectrometric and computational approach.

Cobaltcarbonyl--butylacetylene (CCTBA) is a conventional precursor for the selective atomic layer deposition of Co onto silicon surfaces. However, a limited understanding of the deposition mechanism of such cobalt precursors curbs rational improvements on their design for increased efficiency and tuneable selectivity. The impact of using a less reactive internal alkyne instead of a terminal alkyne was investigated using experimental and computational methods.

The unanti-cipated oxidation of a tertiary amine in a tetra-cyclic glyoxal-cyclam condensate yielding zinc(II) coordinated to a sterically hindered amine oxide.

The complex, tri-chlorido-(1,4,11-tri-aza-8-azonia-tetra-cyclo-[6.6.2.

Next-Generation 3,3'-AlkoxyBTPs as Complexants for Minor Actinide Separation from Lanthanides: A Comprehensive Separations, Spectroscopic, and DFT Study.

Progress toward the closure of the nuclear fuel cycle can be achieved if satisfactory separation strategies for the chemoselective speciation of the trivalent actinides from the lanthanides are realized in a nonproliferative manner. Since Kolarik's initial report on the utility of bis-1,2,4-triazinyl-2,6-pyridines (BTPs) in 1999, a perfect complexant-based, liquid-liquid separation system has yet to be realized. In this report, a comprehensive performance assessment for the separation of Am from Eu as a model system for spent nuclear fuel using hydrocarbon-actuated alkoxy-BTP complexants is described.

Nitrous oxide tank cold burn to the forearm: a case study and discussion of the literature.

Nitrous oxide (N 2 O) has become one of the most popular recreational drugs in Europe. While N 2 O is often used in medical settings as an analgesic and anaesthetic agent, its recreational use was documented many years before its introduction into clinical practice. The desired effects from inhaling N 2 O for recreational purposes include rapid feelings of relaxation, calmness and euphoria, which can be accompanied by giddiness and laughter.

Controlling Electron Delocalization in Vanadium-Based Hybrid Bronzes through Molecular Templation.

We show that the conductivity of hybrid vanadium bronzes-mixed-valence organic-inorganic vanadium oxides-can be tuned over six orders of magnitude through judicious choice of molecular component. By systematically varying the steric profile, charge density, and propensity to hydrogen bond across a series of eight diammonium-based molecules, we engender multiple distinct motifs of V-O connectivity within the two-dimensional vanadium oxide layers of a family of bulk crystalline hybrid materials. A combination of single-crystal and powder X-ray diffraction analysis, variable-temperature electrical transport measurements, and a range of spectroscopic methods, including UV/Visible diffuse reflectance, X-ray photoelectron, and electron paramagnetic resonance are employed to probe how vanadium oxide layer topology correlates with electron localization.

Synthesis and biological evaluation of -inspired antimicrobials.

Due to the lack of new antimicrobial drug discovery in recent years and an ever-growing prevalence of multidrug-resistant "superbugs", there is a pressing need to explore alternative ways to combat pathogenic bacterial and fungal infections. Building upon our previous work in the field of medicinal phytochemistry, the present study is focused on designing, synthesizing, and testing the altered bioactivity of new variants of two original bioactive molecules found in the plant. Herein, we report upon 14 variants of berberine and four variants of chelerythrine that have been screened against a pool of 12 microorganisms (five Gram-positive and four Gram-negative bacteria, and three fungi).

Earth Abundant Oxidation Catalysts for Removal of Contaminants of Emerging Concern from Wastewater: Homogeneous Catalytic Screening of Monomeric Complexes.

Twenty novel Mn, Fe, and Cu complexes of ethylene cross-bridged tetraazamacrocycles with potentially copolymerizable allyl and benzyl pendant arms were synthesized and characterized. Multiple X-ray crystal structures demonstrate the cis-folded pseudo-octahedral geometry forced by the rigidifying ethylene cross-bridge and show that two cis coordination cites are available for interaction with substrate and oxidant. The Cu complexes were used to determine kinetic stability under harsh acidic and high-temperature conditions, which revealed that the cyclam-based ligands provide superior stabilization with half-lives of many minutes or even hours in 5 M HCl at 50-90 °C.

Evidence for Uranium(VI/V) Redox Supported by 2,2'-Bipyridyl-6,6'-dicarboxylate.

The 2,2'-bipyridyl-6,6'-dicarboxylate ligand () has been shown in prior work to effectively capture the uranyl(VI) ion, UO, from aqueous solutions. However, the redox properties of the uranyl complex of this ligand have not been addressed despite the relevance of uranium-centered reduction to the nuclear fuel cycle and the presence of a bipyridyl core in , a motif long recognized for its ability to support redox chemistry. Here, the complex of UO () has been synthetically prepared and isolated under nonaqueous conditions for the study of its reductive chemical and electrochemical behavior.

Insight into the Structural Ambiguity of Actinide(IV) Oxalate Sheet Structures: A Case for Alternate Coordination Geometries.

Invited for the cover of this issue is the group of Amy Hixon at the University of Notre Dame. The image depicts the newly identified structure of a Pu oxalate sheet compared to the historically assumed structure. Read the full text of the article at 10.

Homoleptic complexes of isocyano- and diisocyanobiazulenes with a 12-electron, ligand-based redox capacity.

Oligo- and polyazulenes are attractive π-conjugated building blocks in designing advanced functional materials. Herein, we demonstrate that anchoring one or both isocyanide termini of the redox non-innocent 2,2'-diisocyano-6,6'-biazulenic π-linker (1) to the redox-active [Cr(CO)] moiety provided a convenient intramolecular redox reference for unambiguously establishing that the 6,6'-biazulenic scaffold undergoes a reversible one-step 2 reduction governed by reduction potential compression/inversion. Treatment of bis(η-naphthalene)chromium(0) with six equiv.

Synthesis and Magnetic Studies of Two Neutral, -Ligand Fe(II) Complexes Containing Carbazole-(tetrazole) Ligands.

Previously reported carbazole-(tetrazole) (CzT) ligands (where R = iPr and CH-2,4,6-CHMe) were used to synthesize air-stable, six-coordinate, octahedral bis-ligand Fe(II) complexes (CzT)Fe. The synthesis and characterization of these complexes using H nuclear magnetic resonance (NMR), X-ray crystallography, Mössbauer spectroscopy, and density functional theory (DFT) calculations are reported. Analysis of the magnetic properties revealed that the isopropyl derivative displays thermally induced spin crossover (SCO) over a temperature range of 150-350 K.

One-bond C-C spin-coupling constants in saccharides: a comparison of experimental and calculated values by density functional theory using solid-state C NMR and X-ray crystallography.

Methyl aldohexopyranosides were C-labeled at contiguous carbons, crystallized, and studied by single-crystal X-ray crystallography and solid-state C nuclear magnetic resonance (NMR) spectroscopy to examine the degree to which density functional theory (DFT) can calculate one-bond C-C spin-coupling constants () in saccharides with sufficient accuracy to permit their use in ' analysis, a newly-reported hybrid DFT/NMR method that provides probability distributions of molecular torsion angles in solution (Zhang , , 2017, , 3042-3058; Meredith , , 2022, , 3135-3141). Experimental values in crystalline samples of the doubly C-labeled compounds were measured by solid-state C NMR and compared to those calculated from five different DFT models: (1) values calculated from single structures identical to those observed in crystalline samples by X-ray crystallography (all atom refinement); (2) values calculated from the single structures in (1) but after Hirshfeld atom refinement (HAR); (3) values calculated from the single structures in (1) after DFT-optimization of hydrogen atoms only; and (4 and 5) values calculated in rotamers of torsion angle (C1-C2-O2-O2H) or (C4-C5-C6-O6) from which either specific or generalized parameterized equations were obtained and used to calculate values in the specific or rotamers observed in crystalline samples. Good qualitative agreement was observed between calculated values and those measured by solid-state C NMR regardless of the DFT model, but in no cases were calculated values quantitative, differing (over-estimated) on average by 4-5% from experimental values.