Combating Li metal deposits in all-solid-state battery via the piezoelectric and ferroelectric effects.

All-solid-state Li-metal batteries (ASSLBs) are highly desirable, due to their inherent safety and high energy density; however, the irregular and uncontrolled growth of Li filaments is detrimental to interfacial stability and safety. Herein, we report on the incorporation of piezo-/ferroelectric BaTiO3 (BTO) nanofibers into solid electrolytes and determination of electric-field distribution due to BTO inclusion that effectively regulates the nucleation and growth of Li dendrites. Theoretical simulations predict that the piezoelectric effect of BTO embedded in solid electrolyte reduces the driving force of dendrite growth at high curvatures, while its ferroelectricity reduces the overpotential, which helps to regularize Li deposition and Li+ flux. Polarization reversal of soft solid electrolytes was identified, confirming a regular deposition and morphology alteration of Li. As expected, the ASSLBs operating with LiFePO4/Li and poly(ethylene oxide) (PEO)/garnet solid electrolyte containing 10% BTO additive showed a steady and long cycle life with a reversible capacity of 103.2 mAh g-1 over 500 cycles at 1 C. Furthermore, the comparable cyclability and flexibility of the scalable pouch cells prepared and the successful validation in the sulfide electrolytes, demonstrating its universal and promising application for the integration of Li metal anodes in solid-state batteries.

Neptunium Alkoxide Chemistry: Expanding Alkoxides to the Transuranium Elements.

Two oxo-containing neptunium(IV) tert-butoxides, [Np3O(OtBu)10] (1) and [K4Np2O(OtBu)10] (2), were synthesized using the ligand substitution between neptunium(IV) silylamides and HOtBu, whereas the salt metathesis between [NpCl4(DME)2] (DME = dimethoxyethane) and various amounts of LiOtBu resulted in the formation of oxo-free alkoxides [Np(OtBu)4(py)2] (3; py = pyridine) and [Li(THF)]2[Np(OtBu)6] (4; THF = tetrahydrofuran). These complexes are the first structurally characterized neptunium(IV) alkoxides using single-crystal X-ray diffraction and solid-state absorption spectroscopy, which provide data for the development of anhydrous metal-organic neptunium chemistry.

Direct Synthesis of Two-Dimensional SnSe and SnSe2 through Molecular Scale Preorganization.

Two-dimensional tin monoselenide (SnSe) and tin diselenide (SnSe2) materials were efficiently produced by the thermolysis of molecular compounds based on a new class of seleno-ligands. Main group metal chalcogenides are of fundamental interest due to their layered structures, thickness-dependent modulation in electronic structure, and small effective mass, which make them attractive candidates for optoelectronic applications. We demonstrate here the synthesis of stable tin selenide precursors by in situ reductive bond cleavage in the dimeric diselenide ligand (SeC2H4N(Me)C2H4Se)2 in the presence of SnCl4. New molecular precursors [SnIV(SeC2H4N(Me)C2H4Se)2], [SnIVCl2(SeC2H4N(Me)C2H4Se)], and [SnIV(SC2H4N(Me)C2H4S)(SeC2H4N(Me)C2H4Se)] were thoroughly characterized by multinuclear magnetic resonance studies and single-crystal X-ray diffraction analysis that revealed the Sn(IV) center to be octahedrally coordinated by two tridentate dianionic chelating ligands or trigonally pyramidally coordinated by one chelating ligand and two chlorido ligands. Preorganization of metal-selenium bonds in both compounds offered direct and reproducible synthetic access to two-dimensional tin chalcogenides (SnSe and SnSe2) via simple adjustment of the pyrolysis temperature. Additionally, SnSe2 and SnSxSe2-x particles could be successfully synthesized by microwave-assisted decomposition of the molecular precursors, which was unambiguously corroborated by both experimental and computational analyses that explained the formation of a selenium rich SnSxSe2-x phase from a single molecular precursor containing both Sn-Se and Sn-S bonds.

Rational design of bifunctional chimeric peptides that combine antimicrobial and titanium binding activity.

Bacterial biofilm formation remains a serious problem for clinical materials and often leads to implant failure. To counteract bacterial adhesion, which initiates biofilm formation, the development of antibiotic surface coating strategies is of high demand and warrants further investigations. In this study, we have created bifunctional chimeric peptides by fusing the recently developed antimicrobial peptide MGD2 (GLRKRLRKFFNKIKF) with different titanium-binding sequences. The novel peptides were investigated regarding their antibacterial potential against a set of different bacterial strains including drug-resistant Staphylococcus aureus. All peptides showed high antimicrobial activities both when in solution and when immobilized on titanium surfaces. Owing to the ease of synthesis and handling, the herein described peptides might be a true alternative to prevent bacterial biofilm formation.

Undirected C-H Bond Activation in Aluminium Hydrido Enaminonates.

Two new aluminium hydrido complexes were synthesized by reacting AlH3 with the enaminone ligand N-(4,4,4-trifluorobut-1-en-3-on)-6,6,6-trifluoroethylamine (HTFB-TFEA) in different molar ratios to obtain mono- and di-hydrido-aluminium enaminonates. Both air and moisture sensitive compounds could be purified via sublimation under reduced pressure. The spectroscopic analysis and structural motif of the monohydrido compound [H-Al(TFB-TBA)2] (3) showed a monomeric 5-coordinated Al(III) centre bearing two chelating enaminone units and a terminal hydride ligand. However, the dihydrido compound exhibited a rapid C-H bond activation and C-C bond formation in the resulting compound [(Al-TFB-TBA)-HCH2] (4a), which was confirmed by single crystal structural data. The intramolecular hydride shift involving the migration of a hydride ligand from aluminium centre to the alkenyl carbon of the enaminone ligand was probed and verified by multi-nuclear spectral studies (1H,1H NOESY, 13C, 19F, and 27Al NMR).

A General Synthesis of Mesoporous Hollow Carbon Spheres with Extraordinary Sodium Storage Kinetics by Engineering Solvation Structure.

Porous and hollow carbon materials have great superiority and prospects in electrochemical energy applications, especially for surface charge storage due to the high active surface. Herein, a general strategy is developed to synthesize mesoporous hollow carbon spheres (MHCS) with controllable texture and compositions by the synergistic effect of dopamine polymerization and metal catalysis (Cu, Bi, Zn). Mesoporous MHCS-Cu and MHCS-Bi are regular spheres, while mesoporous MHCS-Zn possesses an inward concave texture, and simultaneously has a very high surface area of 1675.5 m2 g-1 and lower oxygen content through the catalytic deoxygenation effect. MHCS-Zn displays an exceptional sodium storage kinetics and excellent long cycling life with 171.9 mAh g-1 after 2500 cycles at 5 A g-1 in compatible ether-based electrolytes. Such electrolyte enables enhanced solvated Na+ transport kinetics with appropriate electrostatic interactions at the surface of carbon anode as revealed by molecular dynamics simulations and molecular surface electrostatic potential calculations. Such an anode also displays basically constant capacity working at 0 °C, and still delivers 140 mAh g-1 at 3 A g-1 under -20 °C. Moreover, MHCS-Zn anode is coupled with Na3 V2 (PO4 )3 cathode to construct a hybrid capacitor, which exhibits a high energy density of 145 Wh Kg-1 at a very high power of 8009 W kg-1 .

Vitreum Etching-Assisted Fabrication of Porous Hollow Carbon Architectures for Enhanced Capacitive Sodium and Potassium-Ion Storage.

Carbonaceous materials exhibit promising application in electrochemical energy storage especially for hollow or porous structure due to the fascinating and outstanding properties. Although there has been achieved good progress, controllable synthesis of hollow or porous carbons with uniform morphology by a green and easy way is still a challenge. Herein, a new artful and green approach is designed to controllably prepare hollow porous carbon materials with the assistance of boron oxide vitreum under a relatively low temperature of 500 °C. The vitreous B2 O3 provides a flowing carbonization environment and acts as etching agent accompanying with boron doping. By this general strategy, hollow and porous carbon architectures with various morphology of spheres and hollow polyhedrons are successfully fabricated by metal organic framework (MOF) precursors. Furthermore, such hollow carbon materials exhibit considerably excellent Na+ /K+ storage properties through enhanced capacitive behavior due to due to the highly porous structure and large surface area. It is notable that hollow carbon spheres display nearly 90% initial Coulombic efficiency, outstanding rate capability with 130 mAh g-1 at 30 A g-1 and long cycling life for sodium ion storage.

Hierarchically Organized Biomimetic Architectured Silk Fibroin-Ceramic-Based Anisotropic Hybrid Aerogels for Thermal Energy Management.

Due to the current energy crises, the search for thermal energy management systems based on thermal insulating porous materials has drawn a significant deal of attention. Herein, we demonstrated the thermal insulation and management capabilities of cuttlefish bone mimetic aerogels with hierarchically organized porous structures directly fabricated from surface-modified and self-assembled silk fibroin (SF) biopolymer extracted from Bombyx mori silkworm cocoon biomass; hereafter, the materials developed referred to as X-AeroSF. Exploiting from creating an interpenetrating network of the secondary ceramic components of various one-, two-, and three-dimensional sepiolite (Mg2H2Si3O9·xH2O), MXene (Ti3C2TX), and silica nanostructures inside the self-assembled SF biopolymer and subsequent uni-directional freeze-casting and drying the resulted hydrogels, composites with aerogel features were obtained. The obtained aerogels possess low bulk density (ρb = 0.059-0.090 g cm-3), low thermal conductivities (λ = 0.035-0.042 W m-1 K-1), and high thermal stability (up to ∼260 °C) with multi-modal lamella-bridge porous microstructures found in the cuttlefish bone structure. In addition, the intriguing anisotropy in the X-AeroSF composite porous structure enables thermal dissipation along with the aligned pore directions, thus decreasing the local overheating on the heated side. As a result, an improvement in thermal insulation in the perpendicular direction with respect to the pore lamellae was obtained. Therefore, the exquisite thermal energy management, biodegradability, low bulk density, fire resistivity, together with possible manufacture scalability of X-AeroSF composite, make this material attractive for future practical applications.

Magnetic Field-Assisted Chemical Vapor Deposition of UO2 Thin Films.

Chemical vapor deposition (CVD) of UO2 thin films from in situ reductive decomposition using a U(VI) precursor ([U(OtBu)6]) was performed under applied magnetic fields (up to 1 T). The molecular mechanism responsible for the formation of U(IV) oxide was determined by nuclear magnetic resonance (NMR) analysis of gaseous byproducts revealed a reductive transformation of uranium hexakis-tert-butoxide into urania. Thin films were grown under zero-field and applied magnetic field conditions that clearly showed the guiding influence of the magnetic field on altering the morphology and crystallographic orientation of grains in UO2 deposits produced under an external magnetic field. Application of magnetic fields was found to reduce the grain size. Whereas films with a ⟨111⟩ preferred orientation were observed under zero-field conditions, the application of magnetic fields (500 mT to 1 T) promoted a polycrystalline growth. X-ray photoelectron spectroscopy confirmed the formation of UO2 films with traces of U(VI) centers present on the surface, which was evidently due to the surface oxidation of coordinatively unsaturated U(IV) centers, which was found to be significantly reduced in the field-assisted process. These findings emphasize the positive effect of magnetic fields on controlling the texture and chemical homogeneity of CVD-grown films. The availability of a magnetic field as an extrinsic parameter for the CVD process adds to the conventional parameters, such as temperature, deposition time, and pressure, and expands the experimental space for thin-film growth.

Molecular Level Synthesis of InFeO3 and InFeO3/Fe2O3 Nanocomposites.

New heterometallic In-Fe alkoxides [InFe(OtBu)4(PyTFP)2] (1), [InFe2(OneoPen)9(Py)] (2), and [InFe3(OneoPen)12] (3) were synthesized and structurally characterized. The arrangement of metal centers in mixed-metal framework was governed by the In:Fe ratio and the coordination preferences of Fe(III) and In(III) centers to be in tetrahedral and octahedral environments, respectively. 3 displayed a star-shaped so-called "Mitsubishi" motif with the central In atom coordinated with three tetrahedral {Fe(OneoPen)4}- anionic units. The deterministic structural influence of the larger In atom was evident in 1 and 2 which displayed the coordination of neutral coligands to achieve the desired coordination number. Thermal decomposition studies of compounds 1-3 under inert conditions with subsequent powder diffraction studies revealed the formation of Fe2O3 and In2O3 in the case of 3 and 2, whereas 1 intriguingly produced elemental In and Fe. In contrary, the thermal decomposition of 1-3 under ambient conditions produced a ternary oxide, InFeO3, with additional Fe2O3 present as a secondary phase in a different stoichiometric ratio predetermined through the In:Fe ratio in 2 and 3. The intimate mixing of different phases in InFeO3/Fe2O3 nanocomposites was confirmed by transmission electron microscopy of solid residues obtained after the decomposition of 1 and 2. The pure InFeO3 particles demonstrated ferromagnetic anomalies around 170 K as determined by temperature-dependent field-cooled and zero-field-cooled magnetization experiments. A first-order magnetic transition with an increase in the ZFC measurements was explained by temperature-induced reduction of the Fe-Fe distance and the corresponding increase in superexchange.

Synthesis, proteolytic stability, and in vitro evaluation of DOTA conjugated p160 peptide based radioconjugates: [177Lu]Lu-DOTA-p160.

In this work, we describe the synthesis, in vitro stability, and preliminary biological evaluation of [177Lu]Lu-DOTA-p160 peptide-based radiopharmaceuticals. Our findings highlight that all DOTA-p160-peptide radioconjugates exhibit favorable proteolytic and enzymatic stability with a prolonged half-life in human plasma and serum. Cell uptake studies carried out on MCF-7 cell line revealed saturable binding of the radioconjugates in the nanomolar range, thereby demonstrating their promising potential in the imaging and therapy of breast tumors.

Piezo-enhanced activation of dinitrogen for room temperature production of ammonia.

The catalytic conversion of nitrogen to ammonia remains an energy-intensive process, demanding advanced concepts for nitrogen fixation. The major obstacle of nitrogen fixation lies in the intrinsically high bond energy (941 kJ mol-1) of the N≡N molecule and the absence of a permanent dipole in N2. This kinetic barrier is addressed in this study by an efficient piezo-enhanced gold catalysis as demonstrated by the room temperature reduction of dinitrogen into ammonia. Au nanostructures were immobilized on thin film piezoelectric support of potassium sodium niobate (K0.5Na0.5NbO3, KNN) by chemical vapor deposition of a new Au(III) precursor [Me2Au(PyTFP)(H2O)]1(PyTFP = (Z)-3,3,3-trifluoro-1-(pyridin-2-yl)-prop-1-en-2-olate) that exhibited high volatility (60 °C, 10-3mbar) and clean decomposition mechanism to produce well adherent elemental gold films on KNN and Ti substrates. The gold-functionalized KNN films served as an efficient catalytic system for ammonia production with a Faradaic efficiency of 18.9% achieved upon ultrasonic actuation. Our results show that the spontaneous polarization of piezoelectric materials under external electrical fields augments the sluggish electron transfer kinetics by creating instant dipoles in adsorbed N2molecules to deliver a piezo-enhanced catalytic system promising for sustained activation of dinitrogen molecules.

Vapor Phase Synthesis of SnS Facilitated by Ligand-Driven "Launch Vehicle" Effect in Tin Precursors.

Extraordinary low-temperature vapor-phase synthesis of SnS thin films from single molecular precursors is attractive over conventional high-temperature solid-state methods. Molecular-level processing of functional materials is accompanied by several intrinsic advantages such as precise control over stoichiometry, phase selective synthesis, and uniform substrate coverage. We report here on the synthesis of a new heteroleptic molecular precursor containing (i) a thiolate ligand forming a direct Sn-S bond, and (ii) a chelating O^N^N-donor ligand introducing a "launch vehicle"-effect into the synthesized compound, thus remarkably increasing its volatility. The newly synthesized tin compound [Sn(SBut)(tfb-dmeda)] 1 was characterized by single-crystal X-ray diffraction analysis that verified the desired Sn:S ratio in the molecule, which was demonstrated in the direct conversion of the molecular complex into SnS thin films. The multi-nuclei (1H, 13C, 19F, and 119Sn) and variable-temperature 1D and 2D NMR studies indicate retention of the overall solid-state structure of 1 in the solution and suggest the presence of a dynamic conformational equilibrium. The fragmentation behavior of 1 was analyzed by mass spectrometry and compared with those of homoleptic tin tertiary butyl thiolates [Sn(SBut)2] and [Sn(SBut)4]. The precursor 1 was then used to deposit SnS thin films on different substrates (FTO, Mo-coated soda-lime glass) by CVD and film growth rates at different temperatures (300-450 °C) and times (15-60 min), film thickness, crystalline quality, and surface morphology were investigated.

Reversible Covalent Assembly of Nanoparticles through On-Surface Diels-Alder Reaction.

We demonstrate here a controlled assembly of individual nanoscale building blocks into defined architectures based on chemospecific covalent bonding interactions. For this purpose, α-Fe2O3, γ-Fe2O3, and SiO2 nanoparticles decorated with surface-conjugated organic ligands were used for performing on-surface Diels-Alder reactions. Driven through their chemical affinity and surface-grafted complementary functionalities, nanoparticles underwent click-reactions to produce covalently organized nanostructures. An advantage of using the Diels-Alder reaction is its reversible nature, which was used to click and unclick the nanoparticles on demand. The efficiency and chemical specificity of this approach opens up another synthetic access to unify materials with complementary properties, where the thermoresponsive nature of particle assemblies imparts to them a fully reversible character. The covalent conjugation strategies demonstrated in this work potentially allow the use of a diverse range of particles and ligands for their applications in different disciplines such as medicine, optics, or photonics. The nanoparticles morphology and crystalline nature were investigated by TEM and XRD analysis, while the presence of surface attached groups was verified by NMR, FTIR, UV-vis, and ζ potential measurements.

Receptor-Mediated In Vivo Targeting of Breast Cancer Cells with 17α-Ethynylestradiol-Conjugated Silica-Coated Gold Nanoparticles.

Efficient therapies for breast cancer remain elusive because of the lack of strategies for targeted transport and receptor-mediated uptake of synthetic drug molecules by cancer cells. Conjugation of nanoparticles (NPs) with active targeting ligands enabling selective molecular recognition of antigens expressed on the surface of cancer cells is promising for localization and treatment of malignant cells. In this study, covalent attachment of synthetic estrogen 17α-ethynylestradiol on the silica (SiO2) shell of silica-gold NPs (SiO2@Au) was undertaken to improve the cancer-targeting ability of the nano-biotags. Chemical and structural analysis of the bioconjugates examined in solution (UV-vis and ξ-potential) and solid state (Fourier transform infrared spectroscopy, X-ray diffractometry, and transmission electron microscopy) confirmed the identity of the carrier particles and surface-bound ligands. The mesoporous silica shell served as a reservoir for anticancer drugs (doxorubicin and quercetin) and to facilitate covalent attachment of receptor molecules by click chemistry protocols. The chemoselective recognition between the nanoconjugates and cell membranes was successfully demonstrated by the accumulation of nanoprobes in the tumor tissue of mice with subcutaneous breast cancer, whereas healthy cells were unaffected. The drug release studies showed sustained release kinetics over several weeks. These findings elaborate the exceptional selectivity and potential of estrogen-coated nano-biolabels in efficient diagnosis and detection of breast cancer cells.

Molecular Routes to Two-Dimensional Metal Dichalcogenides MX2 (M = Mo, W; X = S, Se).

New synthetic access to two-dimensional transition metal dichalcogenides (TMDCs) is highly desired to exploit their extraordinary semiconducting and optoelectronic properties for practical applications. We introduce here an entirely novel class of molecular precursors, [MIV(XEtN(Me)EtX)2] (MIV = MoIV, WIV, X = S, Se), enabling chemical vapor deposition of TMDC thin films. Molybdenum and tungsten complexes of dianionic tridentate pincer-type ligands (HXEt)2NR (R = methyl, tert-butyl, phenyl) produced air-stable monomeric dichalcogenide complexes, [W(SEtN(Me)EtS)2] and [Mo(SEtN(Me)EtS)2], displaying W and Mo centers in an octahedral environment of 4 S and 2 N donor atoms. Owing to their remarkable volatility and clean thermal decomposition, both Mo and W complexes, when used in the chemical vapor deposition (CVD) process, produced crystalline MoS2 and WS2 thin films. X-ray diffraction analysis and atomic-scale imaging confirmed the phase purity and 2D structural characteristics of MoS2 and WS2 films. The new set of ligands presented in this work open ups convenient access to a scalable and precursor-based synthesis of 2D transition metal dichalcogenides.

Volatile Rhenium(I) Compounds with Re-N Bonds and Their Conversion into Oriented Rhenium Nitride Films by Magnetic Field-Assisted Vapor Phase Deposition.

New heteroleptic rhenium(I) compounds, [fac-Re(I)(CO)3(L)] (e.g., L= tfb-dmpda, (N,N-(4,4,4-trifluorobut-1-en-3-on)-dimethyl propylene diamine)), containing anionic and neutral ligands act as efficient precursors to grow polycrystalline rhenium nitride (ReN) films by their vapor phase deposition at 600 °C. Deposition of ReN films under an external magnetic field showed an orientation effect with preferred growth of crystallites along ⟨100⟩ direction. Rhenium complexes reported here unify high stability and reactivity in a single molecule through a Janus-type coordination around a Re center, constituted by a chelating tridentate ligand and three carbonyl groups imparting a facial geometry. Single-crystal diffraction analysis confirmed the structural integrity of the new rhenium compounds. The rigidity of molecular framework was validated in solution via 1D and 2D NMR spectroscopy, in the gas phase via mass spectrometry, and in the solid-state by thermogravimetric analysis and differential scanning calorimetry studies. The analytical data showed that pre-existent Re-N bonds in [fac-Re(I)(CO)3(L)] facilitated low-temperature formation of crystalline ReN deposits confirmed by grazing angle X-ray diffraction analysis. The surface chemical composition and the uniformity of microstructure were provided by X-ray photoelectron spectroscopy (XPS) and scanning and transmission electron microscopy (SEM/TEM), respectively.

Chemical Vapor Deposition of Phase-Pure Uranium Dioxide Thin Films from Uranium(IV) Amidate Precursors.

Homoleptic uranium(IV) amidate complexes have been synthesized and applied as single-source molecular precursors for the chemical vapor deposition of UO2 thin films. These precursors decompose by alkene elimination to give highly crystalline phase-pure UO2 films with an unusual branched heterostructure.

Multicolor Gold-Silver Nano-Mushrooms as Ready-to-Use SERS Probes for Ultrasensitive and Multiplex DNA/miRNA Detection.

Uniform silver-containing metal nanostructures with strong and stable surface-enhanced Raman scattering (SERS) signals hold great promise for developing ultrasensitive probes for biodetection. Nevertheless, the direct synthesis of such ready-to-use nanoprobes remains extremely challenging. Herein we report a DNA-mediated gold-silver nanomushroom with interior nanogaps directly synthesized and used for multiplex and simultaneous SERS detection of various DNA and RNA targets. The DNA involved in the nanostructures can act as not only gap DNA (mediated DNA) but also probe DNA (hybridized DNA), and DNA's involvement enables the nanostructures to have the inherent ability to recognize DNA and RNA targets. Importantly, we were the first to establish a new method for the generation of multicolor SERS probes using two different strategies. First Raman-labeled alkanethiol probe DNA was assembled on gold nanoparticles, and second, thiol-containing Raman reporters were coassembled with the probe DNA. The ready-to-use probes also give great potential to develop ultrasensitive detection methods for various biological molecules.

Three at a Time: Step by Step to Heterotermetallic Molecules.

New structural motifs in ternary metal alkoxides are demonstrated through synthetic strategies that enable overcoming statistical barriers and solution equilibrium. Tetradentate dimetalate unit, {M2(OiPr)9}- (M = Hf (1), Zr (2)), used to sequester the coordination sphere of the central metal atom (Ba), allowed step-by-step construction of termetallic molecules [{M'(OiPr)4}(HOiPr)Ba{M2(OiPr)9}] (M' = Al (3), Ga (4), M = Hf; M' = Al, M = Zr (5)). In contrast to a common "coordinative-fit" approach mainly used for bimetallic compounds, this stepwise rational construction using fast successive salt metathesis reactions circumvents general challenges in the syntheses of termetallic alkoxides by avoiding the thermodynamically preferred formation of bimetallic alkoxide molecules. The presented compounds exhibit for the first time gas phase stable termetallic alkoxide frameworks.