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Metal organochalcogenides (MOCs) are an emerging class of luminescent hybrid organic–inorganic semiconductors, whose structures and properties can be tuned by organic functionalization and substitutions of their metal and chalcogen elements. Herein, we present a new design strategy by heterocyclic modification, resulting in the transformation of prototypical two-dimensional (2D) silver phenylselenide (AgSePh) to a zero-dimensional (0D) silver pyridinylselenide (AgSePy) via the formation of Ag–N bonds. At room temperature, AgSePy shows strong and broad orange photoluminescence (PL; λmax= 636 nm, full-width-at-half-maximum = 111 nm, quantum yield = 64%) with a large 259 nm Stoke’s shift and a 3.4 μs lifetime. Using steady-state and time-resolved PL spectroscopy under varying temperature and oxygen conditions, we found AgSePy to exhibit air-stable luminescence and maintain a high PL quantum yield and a single exponential PL lifetime down to 4 K. Furthermore, AgSePy shows excellent thermal stability up to ∼250 °C and chemical stability against polar, nonpolar, and aqueous solvents at pH 3–14. Density functional theory calculations further confirm the 0D electronic structure. Finally, we successfully demonstrated the performance of AgSePy as an X-ray scintillator with an estimated light yield of ∼8,000 phe/MeV and a spatial resolution down to 0.080 ± 0.005 mm. Overall, this work provides a novel tactic to modify the structures and properties of MOCs, highlighting their structural richness and structure–property relationship, and introduces their new use as X-ray scintillators, encouraging further development in radiation detection and medical imaging.

Accurate virtual high-throughput screening (VHTS) of transition metal complexes (TMCs) remains challenging due to the possibility of high multireference (MR) character that complicates property evaluation. We compute MR diagnostics for over 5,000 ligands present in previously synthesized octahedral mononuclear transition metal complexes in the Cambridge Structural Database (CSD). To accomplish this task, we introduce an iterative approach for consistent ligand charge assignment for ligands in the CSD. Across this set, we observe that the MR character correlates linearly with the inverse value of the averaged bond order over all bonds in the molecule. We then demonstrate that ligand additivity of the MR character holds in TMCs, which suggests that the TMC MR character can be inferred from the sum of the MR character of the ligands. Encouraged by this observation, we leverage ligand additivity and develop a ligand-derived machine learning representation to train neural networks to predict the MR character of TMCs from properties of the constituent ligands. This approach yields models with excellent performance and superior transferability to unseen ligand chemistry and compositions.

Modifying the optoelectronic properties of nanostructured materials through the introduction of dopant atoms has attracted intense interest, but the approaches employed are often trial and error, preventing rational design. We demonstrate the power of large-scale electronic structure calculations with density functional theory (DFT) to build an atlas of preferred sites for a range of M(II) and M(III) dopants in the representative III–V InP magic size cluster (MSC). We quantify the thermodynamic favorability of doping, which we identify to be both specific to the sites within the MSC (i.e., interior vs surface) and to the nature of the dopant atom (i.e., smaller Ga(III) vs larger Y(III) or Sc(III)). For isovalent M(III) doping (i.e., Y, Sc, or Ga), we observe stronger sensitivity of the predicted energetics to the ligand binding mode on the surface than to the dopant type. For M(II) (i.e., Zn or Cd) dopants, we show that the binding mode of ligand removed to balance charge during the doping reaction is critical. We observe limited cooperativity with dopants up to moderate concentrations, indicating that rapid single-dopant estimations of favorability from DFT can efficiently guide rational design.

The magnetism of metal nanoclusters (NCs) with discrete electronic structures differs from that of metallic-state nanoparticles. Among the gold NCs, magnetic ones are rare. While 7e [Au25(SR)18]0(SR = thiolate) was an earlier reported one to be magnetic, its spin properties are yet to be understood. Here, we report the silver-doping effect on the magnetic properties of a series of [Au25–xAgx(SR)18]0with xranging from 1 to maximum 9 through analysis by electron paramagnetic resonance (EPR) spectroscopy. This series of M25(M = Au/Ag) NCs reveals a linear decrease in axial splitting with increasing Ag doping owing to smaller spin–orbit coupling for Ag in comparison to Au, and X-ray crystallography analysis reveals the sites for Ag doping, which provides a basis for understanding the spin properties. The influence of aromatic vs nonaromatic ligands on the EPR signals has also been compared. The electronic structures of M25NCs have been computed. Overall, this work demonstrates an effective strategy to manipulate the spin properties of NCs by atomically controlled Ag doping.

Dipole moment (μ) is a critical parameter for molecules and nanomaterials as it affects many properties. In metal–thiolate (SR) nanoclusters (NCs), μ is commonly low (0–5 D) compared to quantum dots. Herein, we report a doping strategy to give giant dipoles (∼18 D) in M23(M = Au/Ag/Cd) NCs, falling in the experimental trend for II–VI quantum dots. In M23NCs, high μ is caused by the Cd–Br bond and the arrangement of heteroatoms along the C3axis. Strong dipole–dipole interactions are observed in crystalline state, with energy exceeding 5 kJ/mol, directing a “head-to-tail” alignment of Au22-nAgnCd1(SR)15X (SR = adamantanethiolate) dipoles. The alignment can be controlled by μ viadoping. The optical absorption peaks of M23show solvent polarity-dependent shifts (∼25 meV) with negative solvatochromism. Detailed electronic structures of M23are revealed by density functional theory and time-dependent DFT calculations. Overall, the doping strategy for obtaining large dipole moments demonstrates an atomic-level design of clusters with useful properties.

Determination of ground-state spins of open-shell transition-metal complexes is critical to understanding catalytic and materials properties but also challenging with approximate electronic structure methods. As an alternative approach, we demonstrate how structure alone can be used to guide assignment of ground-state spin from experimentally determined crystal structures of transition-metal complexes. We first identify the limits of distance-based heuristics from distributions of metal–ligand bond lengths of over 2000 unique mononuclear Fe(II)/Fe(III) transition-metal complexes. To overcome these limits, we employ artificial neural networks (ANNs) to predict spin-state-dependent metal–ligand bond lengths and classify experimental ground-state spins based on agreement of experimental structures with the ANN predictions. Although the ANN is trained on hybrid density functional theory data, we exploit the method-insensitivity of geometric properties to enable assignment of ground states for the majority (ca. 80–90%) of structures. We demonstrate the utility of the ANN by data-mining the literature for spin-crossover (SCO) complexes, which have experimentally observed temperature-dependent geometric structure changes, by correctly assigning almost all (>95%) spin states in the 46 Fe(II) SCO complex set. This approach represents a promising complement to more conventional energy-based spin-state assignment from electronic structure theory at the low cost of a machine learning model.

Pathological crystallization of calcium oxalate monohydrate (COM) is a critical process in human kidney stone disease. Methods of curtailing COM growth involve the action of natural and synthetic polyprotic acids, which selectively bind to crystal surfaces and inhibit the anisotropic rates of growth. Here we use a combination of bulk crystallization, in situscanning probe microscopy, density functional theory, and physiologically relevant in vitroassays to elucidate the molecular origins of COM growth inhibition, focusing on citrate (CA) and its molecular analogues hydroxycitrate (HCA) and isocitrate (ICA). These three molecules differ only in the number and/or placement of hydroxyl groups, yet each exhibit unique binding modes to COM crystal surfaces. A major breakthrough in the development of potential therapies came from the recent discovery of HCA being a potent inhibitor possessing an ability to dissolve crystal surfaces in supersaturated media. Using a combination of experiments and computational calculations, we examine the differentiating factors for isostructural analogues of citrate to prompt dissolution and introduce a vectorized displacement parameter that accounts for strain induced on a crystal lattice as a result of inhibitor adsorption. We also compare the inhibitory effects of all three polyprotic acids in a human urine assay that surprisingly revealed HCA to be a far superior inhibitor than laboratory estimates owing to an apparent synergistic cooperative effect with species in the urine milieu. Collectively, these findings identify new inhibitors of calcium oxalate crystallization and demonstrate that HCA and ICA are promising alternatives to citrate, the current therapy.

Crystalline materials are crucial to the function of living organisms, in the shells of molluscs, the matrix of bone, the teeth of sea urchins, and the exoskeletons of coccoliths. However, pathological biomineralization can be an undesirable crystallization process associated with human diseases. The crystal growth of biogenic, natural and synthetic materials may be regulated by the action of modifiers, most commonly inhibitors, which range from small ions and molecules to large macromolecules. Inhibitors adsorb on crystal surfaces and impede the addition of solute, thereby reducing the rate of growth. Complex inhibitor–crystal interactions in biomineralization are often not well elucidated. Here we show that two molecular inhibitors of calcium oxalate monohydrate crystallization—citrate and hydroxycitrate—exhibit a mechanism that differs from classical theory in that inhibitor adsorption on crystal surfaces induces dissolution of the crystal under specific conditions rather than a reduced rate of crystal growth. This phenomenon occurs even in supersaturated solutions where inhibitor concentration is three orders of magnitude less than that of the solute. The results of bulk crystallization, in situ atomic force microscopy, and density functional theory studies are qualitatively consistent with a hypothesis that inhibitor–crystal interactions impart localized strain to the crystal lattice and that oxalate and calcium ions are released into solution to alleviate this strain. Calcium oxalate monohydrate is the principal component of human kidney stones and citrate is an often-used therapy, but hydroxycitrate is not. For hydroxycitrate to function as a kidney stone treatment, it must be excreted in urine. We report that hydroxycitrate ingested by non-stone-forming humans at an often-recommended dose leads to substantial urinary excretion. In vitro assays using human urine reveal that the molecular modifier hydroxycitrate is as effective an inhibitor of nucleation of calcium oxalate monohydrate nucleation as is citrate. Our findings support exploration of the clinical potential of hydroxycitrate as an alternative treatment to citrate for kidney stones.

Purpose Dialysis venous pressure monitoring has been widely recommended as a surveillance method but has not been shown to improve access outcomes in randomised controlled trials. The method has been impaired by the need to either turn off the blood pump or to derive the static venous pressure from the venous pressure measured with the dialysis pump running. We have developed a unique algorithm which converts Doppler-shifted spectral information derived from unsealed pulsatile blood flow waveforms into an estimate of mean blood pressure (MBP) at the point of ultrasound insonation.Methods We have devised the unique expression shown here: MBP = MAP/(1 + Pff/Vff) where MAP is the mean arterial pressure, Pff = (systolic – diastolic)/MAP measured on the contralateral arm and Vff = spectral maximum – minimum/mean. Venous conductance (VC) can be measured by combining this pressure data with Duplex ultrasound blood flow data. A new device BlueDop™ has been used to illustrate the potential clinical value of non-invasive static pressure ratio (SPRn) in a monitoring role. Duplex and BlueDop™ technology were tested in an arterio-venous fistula (AVF) study in which VC, Qand SPRnwere compared. Thresholds used for detection of ≥60% venous stenosis were VC <10 mL min−1mm Hg−1, Q <500 mL min−1, SPRn >0.56.Results The following accuracy was achieved: VC= 96%, Q = 92%, SPRn= 76% with similar accuracy in predicting premature thrombosis.Conclusions A new algorithm has been described and its in vivoaccuracy in estimating mean ‘pressure from flow’ has been confirmed. Two new variables and a new dedicated instrument BlueDop™ have been demonstrated in clinical use.

We have shown from both simulations and experiments that zwitterion functionalized carbon nanotubes (CNTs) can be used to construct highly efficient desalination membranes. Our simulations predicted that zwitterion functional groups at the ends of CNTs allow a high flux of water, while rejecting essentially all ions. We have synthesized zwitterion functionalized CNT/polyamide nanocomposite membranes with varying loadings of CNTs and assessed these membranes for water desalination. The CNTs within the polyamide layer were partially aligned through a high-vacuum filtration step during membrane synthesis. Addition of zwitterion functionalized CNTs into a polyamide membrane increased both the flux of water and the salt rejection ratio. The flux of water was found to increase by more than a factor of 4, from 6.8 to 28.7 GFD (gallons per square foot per day), as the fraction of CNTs was increased from 0 to 20 wt %. Importantly, the ion rejection ratio increased slightly from 97.6% to 98.6%. Thus, the nanotubes imparted an additional transport mechanism to the polyamide membrane, having higher flow rate and the same or slightly better selectivity. Simulations show that when two zwitterions are attached to each end of CNTs having diameters of about 15 Å, the ion rejection ratio is essentially 100%. In contrast, the rejection ratio for nonfunctionalized CNTs is about 0%, and roughly 20% for CNTs having five carboxylic acid groups per end. The increase in ion rejection for the zwitterion functionalized CNTs is due to a combination of steric hindrance from the functional groups partially blocking the tube ends and electrostatic repulsion between functional groups and ions, with steric effects dominating. Theoretical predictions indicate that an ideal CNT/polymer membrane having a loading of 20 wt % CNTs would have a maximum flux of about 20000 GFD at the conditions of our experiments.

A polymerase chain reaction (PCR) method has been used to confirm the presence of tuberculosis bacterial DNA in extracts of three human bone specimens with lesions suggestive of this disease. A fused wrist bone and a lumbar vertebra from the mediaeval period were found to be positive and an adjacent lumbar vertebra was weakly positive. A control vertebra from the same period (1350–1538ad) from an individual with bone lesions characteristic of syphilis was negative.Against a background of partially degraded DNA, nested PCR was found to be superior for detecting tuberculosis bacterial sequences compared with reamplification of first-round products or modification of other PCR stages. DNA survival in bone was assessed using PCR for a human-specific region of theAlurepetitive short interspersed nucleotide elements (SINES) and the ability to amplify a single copy gene. Genomic DNA was found in all bones examined but the single copy gene did not amplify from the vertebra weakly positive for tuberculosis or the control. This may represent relatively poor DNA preservation in these samples.These findings corroborate the use of PCR as an aid in the study of infectious disease in ancient bone samples and stress the importance of assessing native DNA survival.

The 13C nmr spectra of solids, acquired using the Cross Polarization/Magic Angle Spinning (CP/MAS) technique, are very sensitive to the detailed nature of crystalline packing. These effects are illustrated in the CP/MAS spectra of the α and β anomers of methyl-D-xylopyranoside. In the spectrum of the α anomer, which crystallizes with two molecules per unit cell, individual spectra can be resolved for the two molecules in the asymmetric unit of this crystal.