Versatile Route Research Articles

A Versatile Route for Converting n-Type ZnO into p-Type: Phosphorus Doping of Nanostructures and Powders

A Versatile Route for Converting n-Type ZnO into p-Type: Phosphorus Doping of Nanostructures and Powders

Microstructure and magnetic properties of Fe-Al2O3 nanocomposites prepared by a versatile facile combustion-based route

Fe-Al2O3 nanocomposites with Al2O3 nanoparticles uniformly dispersed have been successfully prepared via a versatile facile and scalable combustion-based route with two steps. Firstly, the homogenous mixed oxide precursor composed with α-Fe2O3, γ-Fe2O3 and Al2O3 was prepared by solution combustion synthesis. Subsequently, Fe-Al2O3 nanocomposites with Al2O3 nanoparticles evenly dispersed were prepared by hydrogen reduction of the mixed oxide precursor. The effects of the various reduction temperatures on the phase composition, morphology, grain size and magnetic properties of the Fe-Al2O3 nanocomposites were investigated in details. The results show that the Fe-Al2O3 nanocomposites prepared at as low as 400 °C present a connected network structure with an average grain size of about 17 nm, which have a saturation magnetization of 125.3 emu/g, and a coercivity of 721.2 Oe. With the increase of reduction temperature, the average grain size, and saturation magnetization of the Fe-Al2O3 nanocomposites increase gradually, while the coercivity decrease. When the reduction temperature is increased to 500 °C and 600 °C, the grain size increases to about 27 nm and 37 nm, the saturation magnetization increases to 153.6 emu/g and 177.1 emu/g, and the coercivity decreases to 634.6 Oe and 467.8 Oe, respectively.

Scalable deoxygenative alkynylation of alcohols via flow photochemistry

Internal alkynes are often contained in bioactive pharmaceuticals and crucial intermediates in material sciences, yet their production methods are often limited and challenging, necessitating the development of more efficient and versatile synthetic routes. Here we report a method of deoxygenative alkynylation of alcohols via flow photochemistry. Formation of N-heterocyclic carbene-alcohol adducts undergoes oxidation by a photocatalyst, generating alkyl radicals. These radicals are subsequently trapped by an alkynylation agent, yielding the desired alkyne. Compared to batch reactions, the strategy using flow photochemistry is practical and efficient to complete the reaction in relatively short time with good yields. A wide range of functional groups were tolerated. The broad application of this method for alkyne synthesis in industry settings is anticipated, supported by the potential in late-stage functionalization of biomolecules and gram-scale synthesis.

ML-Assisted Structural Tuning of Pyridinium Anolytes for Low Reduction Potentials with High Radical Persistence

In the search for useful redox-active materials for redox flow batteries (RFBs), organic compounds offer a massive design space. Attractive anolyte candidates should be easily and inexpensively produced while exhibiting very low reduction potentials, rapid electrode kinetics, high solubility, low viscosity, and very high persistence of the reduced state. However, it is often the case that molecular modifications intended to improve one of these properties will negatively impact one or more of the others, and the ideal anolyte remains elusive. Our group has largely focused on studying substituted pyridinium salts as potential anolytes for nonaqueous RFBs by accessing them via a simple yet extremely versatile synthetic route utilizing readily accessible pyrylium salts as key intermediates. Previous work from our team identified a surprising positive correlation between the number and strength of C-H—π interactions in the solid state and solubility, enabling us to achieve high solubility while maintaining low viscosity and fast electrode kinetics. In this talk, we will describe the use of an ML approach to identify substitution patterns that allow optimization of radical persistence while preserving low reduction potentials.

Photo(Multicomponent) Reaction of Quinoxalin‐2(1H)‐ones with CBrCl3 and Styrenes by Mes‐Acr‐MeClO4

AbstractIn this study, we explored the use of Mes‐Acr‐MeClO4 as a visible light photocatalyst for multicomponent reactions involving quinoxalin‐2(1H)‐ones with CBrCl3 and styrene. The method showcases regioselective functionalization of quinoxalin‐2(1H)‐ones in a three‐component system, forming two C─C bonds in one pot. Mechanistic investigations suggest a radical‐mediated pathway, initiated by the photoexcitation of Mes‐Acr‐MeClO4, followed by halogen atom abstraction from CBrCl3. This approach provides a versatile and sustainable route for quinoxalin‐2(1H)‐one functionalization, with Mes‐Acr‐MeClO4 effectively facilitating the photocatalyzed multicomponent reaction under mild conditions and visible light irradiation, yielding high selectivity and efficiency.

Highly Cytotoxic Cryptophycin Derivatives with Modification in Unit D for Conjugation.

Cytotoxic payloads for drug conjugates suitable for directed tumor therapy need to be highly potent and require a functional group for conjugation with the homing device (antibody, peptide, or small molecule). Cryptophycins are cyclodepsipeptides that stand out from the realm of natural products due to their extraordinarily high cytotoxicity. However, the installation of a suitable conjugation handle without compromising the toxicity is highly challenging. The unit D, natively 2-hydroxyisocaproic acid (leucic acid), was envisaged as a promising attachment site based on structural information from X-ray analysis. A versatile, scalable and efficient synthetic route towards conjugable cryptophycins with modification in unit D was developed and an array of new cryptophycin analogues was synthesized. Several derivatives, especially those containing lipophilic groups with low steric demand such as alkylated amino groups, exhibit low picomolar cytotoxicity often combined with efficacy against multidrug-resistant tumor cells. The newly established cryptophycin analogues comprise a broad range of relevant functional groups used as conjugation handles, among them amino, hydroxy, carboxy, as well as sulfur-containing derivatives. X-ray crystallographic analysis of a tubulin-bound cryptophycin together with quantitative structure activity relationship manifested rationales for the synthesis of most potent cryptophycin derivatives and further confirmed the suitability of modifications in unit D.

Multicore@shell nanoparticle synthesis from a single multicomponent target by gas aggregation source

Synthesis of multifunctional nanomaterials is known as a critical challenge in advanced nanoscience. Multicore@shell nanostructures are generated here via a gas phase synthesis approach. To achieve this objective, we used conventional DC magnetron sputtering in conjunction with a gas aggregation chamber. We employed a customized Au-Ti target to produce metal-metal oxide multicore@shell nanoparticles (NPs) with tunable properties. The deposited NPs were characterized with regard to their chemical composition, morphology, structural status, NP size distribution and optical properties. The obtained data clearly confirms that the crystalline Au cores are encapsulated in a TiOx matrix in each individual NP. Furthermore, the chemical composition and size distribution of the NPs can be affected by the operating pressure. Our approach provides a versatile route with many different possibilities to synthesize multicore@shell NPs from a variety of composite targets for well-desired applications including environmental, optical/plasmonic, and energy.

One-Pot Hybridization of Microfibrillated Cellulose and Hydroxyapatite as a Versatile Route to Eco-Friendly Mechanical Materials.

Hydroxyapatite was crystallized in an alkaline dispersion of mechanically fibrillated cellulose to prepare their composites with hydroxyapatite contents of 26-86 wt %. The composite powder was uniaxially pressed at 120 °C and 300 MPa to obtain the compacts. Three-point bending tests revealed that the bending strengths of the compacts were 40-100 MPa, and the elastic moduli were 4-9 GPa. The composite containing 43% hydroxyapatite showed the largest bending strength and the largest work of fracture, and the composite containing 62% hydroxyapatite showed the largest elastic modulus. The composites, derived from the bioderived eco-friendly materials, showed the mechanical properties comparable to those of engineering plastics such as polyamide-6. Scanning electron microscopic observation of the fracture surface showed that the organic phase was discontinuous when the hydroxyapatite weight fraction was increased from 43% to 62%, and the compacts with a discontinuous organic phase lost toughness.

Tuning Optical and Electrical Properties of Vanadium Oxide with Topochemical Reduction and Substitutional Tin.

Vanadium oxides are widely tunable materials, with many thermodynamically stable phases suitable for applications spanning catalysis to neuromorphic computing. The stability of vanadium in a range of oxidation states enables mixed-valence polymorphs of kinetically accessible metastable materials. Low-temperature synthetic routes to, and the properties of, these metastable materials are poorly understood and may unlock new optoelectronic and magnetic functionalities for expanded applications. In this work, we demonstrate topochemical reduction of α-V2O5 to produce metastable vanadium oxide phases with tunable oxygen vacancies (>6%) and simultaneous substitutional tin incorporation (>3.5%). The chemistry is carried out at low temperature (65 °C) with solution-phase SnCl2, where Sn2+ is oxidized to Sn4+ as V5+ sites are reduced to V4+ during oxygen vacancy formation. Despite high oxygen vacancy and tin concentrations, the transformations are topochemical in that the symmetry of the parent crystal remains intact, although the unit cell expands. Band structure calculations show that these vacancies contribute electrons to the lattice, whereas substitutional tin contributes holes, yielding a compensation doping effect and control over the electronic properties. The SnCl2 redox chemistry is effective on both solution-processed V2O5 nanoparticle inks and mesoporous films cast from untreated inks, enabling versatile routes toward functional films with tunable optical and electronic properties. The electrical conductance rises concomitantly with the SnCl2 concentration and treatment time, indicating a net increase in density of free electrons in the host lattice. This work provides a valuable demonstration of kinetic tailoring of electronic properties of vanadium-oxygen systems through top-down chemical manipulation from known thermodynamic phases.

Tribological properties of oil impregnated carbon nanocapsules modified with polydopamine-polyethyleneimine

Self-lubricating microcapsules can reduce the coefficient of friction/wear and improve the tribological properties of polymer composites. Impregnation of prefabricated shell with core substances is a versatile and applicable route to obtain the microcapsules. In this work, double shell nanocapsules (PA@C HSM) with particle size of 448 nm, shell thickness of 65 nm are obtained by incorporating paraffin wax (PA) into the pre-synthesized hollow carbon nanospheres (PHCs)and then packaged by co-depositing with polydopamine (PDA) and polyethylenimine (PEI). The PDA/PEI transition shell increase the surface roughness of the nanocapsule and enhance the compatibility with the polymer matrix which will contribute to the improved oil storage ability and thermal stability of the nanocapsules as well. The distinguished mechanical interlocking and chemical interface bonding between PDA/PEI layer and EP matrix effectively facilitates mitigating the unfavorable impact of PA@C HSM on the mechanical properties of the composite with the modulus of the 7.5 wt% PA@C HSM/EP composites increased by 17.44 %. As for the tribological performance of PA@C HSM/EP composite, the tribological properties are boosted remarkably and the friction coefficient and wear rate of 7.5 %PA@C HSM/EP composite are reduced by 77.69 % and 98.79 % compared with pure EP material.

Photoredox Oxidation of Alkanes by Monometallic Copper-Oxygen Complexes Using Visible Light Including One Sun Illumination.

Oxygenation of hydrocarbons offers versatile catalytic routes to more valuable compounds, such as alcohols, aldehydes, and ketones. Despite the importance of monometallic copper-oxygen species as hydroxylating agents in biology, few synthetic model compounds are known to react with hydrocarbons, owing to high C-H bond dissociation energies. To overcome this challenge, the photoredox chemistry of monometallic copper (pyrazolyl)borate complexes coordinated by chlorate has been explored in the presence of C1-C6 alkanes with BDEs ≥ 93 kcal/mol. Ethane is photooxidized at room temperature under N2 with yields of 15-30%, which increases to 77% for the most oxidizing tris(3,5-trifluoromethyl-pyrazolyl)borate complex (Cu-3). This complex also promotes the photooxidation of methane to methanol in significant yield (38%) when the photoredox reaction is run under aerobic conditions. Ligand modification alters the reaction selectivity by tuning the redox potential. The ability to activate 1° C-H bonds of C1-C6 alkanes using visible light is consistent with the photogeneration of a powerfully oxidizing copper-oxyl, which is supported by photocrystallographic studies of the tris(3,4,5-tribromopyrazolyl)borate chlorate complex. Mechanistic studies are consistent with the hydrogen atom abstraction of the C-H bond by the copper-oxyl intermediate. We demonstrate for Cu-3 with hexane as an exemplar, that the photoredox chemistry may be achieved under solar conditions of one-sun illumination.

Highly Selective Electrosynthesis of 1H-1-Hydroxyquinol-4-ones-Synthetic Access to Versatile Natural Antibiotics.

1H-1-Hydroxyquinolin-4-ones represent a broad class of biologically active heterocycles having an exocyclic N,O motif. Electrosynthesis offers direct, highly selective, and sustainable access to 1-hydroxyquinol-4-ones by nitro reduction. A versatile synthetic route starting from easily accessible 2-nitrobenzoic acids was established. The broad applicability of this protocol was demonstrated on 26 examples with up to 93% yield, highlighted by the naturally occurring antibiotics Aurachin C and HQNO. The practicability and technical relevance were underlined by multigram scale electrolysis.

Multi‐Hierarchical Fe Single Atom Nanozymes with Axially‐Coordinated O‐Fe‐N4 Active Centers Reshape Macrophage Epigenetics Against Immunosuppression

AbstractImmunosuppression is ubiquitous in solid tumors, characterized by few cytotoxic T infiltrations, abundant inflammation enrichment, immunosuppressive cell recruitment, etc., which is especially potentiated by incomplete tumor resection. In this report, multi‐hierarchical Fe single‐atom nanozymes (SAzymes) featuring axially‐coordinated O‐Fe‐N4 active centers are constructed to reshape tumor‐associated macrophages (TAMs) epigenetics via repolarizing their phenotypes, which is highly profitable for mitigating tumor immunosuppression after incomplete radiofrequency ablation (iRFA). Therein, a nitrogen‐doped bamboo‐like carbon nanotube (N‐BCNT) is engineered to coordinatively immobilize Fe atoms, wherein another axial coordination (O) is introduced to further switch non‐polar Fe‐N4 to polar O‐Fe‐N4. The polarization switching of active centers synergies with N doping‐encouraged electron transport, low‐temperature synthesis‐discouraged N loss and large surface area‐unlocked O‐Fe‐N4 enrichment to confer tetra‐enzymic catalysis activities including peroxidase, oxidase, catalase, and glutathione oxidase, maximumly favoring reactive oxygen species (ROS) production and hypoxia reversal. After delivering TAMs polarization‐encouraged drug, toosendanin, TAMs epigenetics are altered and their phenotypes are repolarized to relieve immunosuppression and magnify immune responses, which suppress residual tumor progression after iRFA. Such a comprehensive structure optimization strategy provides a versatile route to design and construct SAzymes‐like drugs with multi‐enzymatical catalysis activities.

Thermo-kinetic insights into deformation mechanism in the phase-transforming nanostructured Fe alloy

Solid-state phase transformations (SSPTs) being the most widely versatile routes to tailor microstructures are less utilized in the design of nanostructured (NS) alloys, resulting in a lack of understanding of the significance of SSPTs in tuning mechanical properties. Here, we combine nanostructuring with reverse austenite transformation to make a phase-transforming NS Fe alloy consisting of ultrafine ferrite and austenite grains. By comparison with the coarse-grained (CG) counterpart, the NS sample exhibits high strengths (i.e., the yield and the ultimate tensile strengths are 816 and 1170 MPa, respectively), good ductility with a uniform elongation of 53 %, and superior strain hardening capacity, under multiple strengthening mechanisms and the activation of transformation induced plasticity. Regarding the mechanism in forming the NS sample, grain refinement is revealed to markedly affect the austenite formation kinetics by generating sluggish growth behavior accompanied by sufficient solute partitioning. Then, we clarify the difference in mechanical responses of the phase-transforming NS and CG samples using a physically based microstructures-properties model. Further based on the thermo-kinetic theory of generalized stability, we show that the simultaneous increase of strength and ductility in the NS sample relative to the CG sample is originated from the deformation physics with higher driving force and higher generalized stability. From the thermo-kinetic perspective, our work demonstrates that the SSPTs hold substantial promise in optimizing the microstructures and the mechanical properties of NS Fe alloys and are expected to find wide application in the development of other NS materials.

Pyridinic-N Regulated Electron Injection to Modulate *OH Adsorption at Fe-N-C Sites for an Efficient Oxygen Reduction Reaction.

To enhance the efficiency of oxygen reduction reaction (ORR) catalysts, precise control over the adsorption/desorption energy barriers of oxygen intermediates at atomically dispersed Fe-N-C sites is essential yet challenging. Addressing this, we employed a pyrolysis approach using a nitrogen-containing polymer to fabricate Fe single-atom (SA) catalysts embedded in a pyridinic-N enriched carbon matrix. This synthesis strategy yielded Fe SAs that demonstrated a superior electrochemical ORR performance, evidenced by an impressive half-wave potential of 0.941 V and a high limiting current density of 5.72 mA/cm2. Moreover, when applied in homemade Zn-air batteries, this premier catalyst exhibited exceptional specific capacity (720 mAh/gZn), peak power density (253 mW/cm2), and notable long-term stability. Theoretical insights revealed that the increased pyridinic-N content in the catalyst facilitated efficient electron transfer from N atoms to the Fe active sites, thus fine-tuning the d-band center and effectively controlling the adsorption energy barrier of *OH species. These mechanisms synergistically improve the ORR performance. Crucially, this fabrication method shows promise for adaptation to other transition metal-based SAs, including Co, Ni, and Cu, potentially establishing a versatile synthesis route for developing atomically dispersed catalyst systems in future applications.

Size-Dependent Photocatalytic Reactivity of Conjugated Microporous Polymer Nanoparticles.

Particle size is a critical factor for improving photocatalytic reactivity of conjugated microporous polymers (CMPs) as mass transfer in the porous materials is often the rate-limiting step. However, due to the synthetic challenge of controlling the size of CMPs, the impact of particle size is yet to be investigated. To address this problem, a simple and versatile dispersion polymerization route that can synthesize dispersible CMP nanoparticles with controlled size from 15 to 180nm is proposed. Leveraging the precise control of the size, it is demonstrated that smaller CMP nanoparticles have dramatically higher photocatalytic reactivity in various organic transformations, achieving more than 1000% enhancement in the reaction rates by decreasing the size from 180 to 15nm. The size-dependent photocatalytic reactivity is further scrutinized using a kinetic model and transient absorption spectroscopy, revealing that only the initial 5nm-thick surface layer of CMP nanoparticles is involved in the photocatalytic reactions because of internal mass transfer limitations. This finding substantiates the potential of small CMP nanoparticles to efficiently use photo-generated excitons and improve energy-efficiency of numerous photocatalytic reactions.

Low MWCO non-polyamide nanofiltration membranes synthesized in aqueous by coupling with catechol-amine chemistry and the oxidation-induced self-polymerization of m-phenylenediamine

Catechol-amine coatings offer versatile routes for surface modifications and nanofiltration (NF) membrane preparations. However, the formation of the selective layer is time-consuming and often deficient, rendering it unsuitable for large-scale applications. In this work, oxidation-induced self-polymerization and catechol-amine chemistry were combined to rapidly construct nanofiltration membranes in an aqueous medium. M-phenylenediamine (MPD) underwent oxidation and self-polymerized on a polysulfone (PSF) support. The addition of sodium periodate facilitated the subsequent tannic acid (TA) coating. The catechol-amine reaction between oxidized TA and poly-MPD forms crosslinked poly TA-MPD complexes, offering the resulting membrane a high selectivity. The role of NaIO4 in the selective layer formation and the influences of the synthesis parameters on the membrane performance were discussed. Utilizing the facile method enabled the achievement of a low molecular weight cut-off (MWCO) NF membrane (180 Da). The membrane exhibited a high water permeance (10.9 Lm−2h−1bar−1) and good salt rejections (93 % for Na2SO4). The filtration of the bovine serum acid (BSA) solution demonstrated the membrane has good antifouling performance with a flux recovery ratio (FRR) of 95.1 %. The proposed method offers a straightforward and rapid approach to fabricating low MWCO NF membranes in an aqueous medium, which has potential in large-scale applications.

Confined growth with particle attachment driven self-sieving for enhanced cascade reaction via versatile core-shell-shell nanocomposites

Controlling formation of metal organic frameworks (MOFs) with embedded enzymes on magnetic surface has been achieved by a confined growth with particle attachment driven self-sieving approach for the first time. Specifically, a versatile route of silica encapsulation guided enzyme assembly for formation of ZIF-8 shell has been successfully demonstrated by shaped-controllable Fe3O4 nanoparticles, e.g., nanorod and nanocube. Interestingly, silica encapsulation can lead to structural diversity of ZIF-8 shell on the shaped-controllable Fe3O4 nanoparticles for affecting properties of the nanocomposites. Furthermore, embedded enzymes confined between silica endoskeleton and ZIF-8 exoskeleton can participate in cascade reaction with different activities and stabilities in the terms of plasmonic assemblies fabrication and cancer cell catalytic therapy. As a result, a circulation plasmonic fabrication and cancer therapy can be achieved via the magnetic nanocomposites. It can be expected that the confined growth with particle attachment driven self-sieving method can be versatile to generate diverse MOFs shell encapsulated shaped-controllable nanoparticles for efficiently embedding enzyme in the nanocomposites.

Deuteration-Induced Energy Level Structure Reconstruction of Carbon Dots for Enhancing Photoluminescence.

Constrained by a limited understanding of the structure and luminescence mechanisms of carbon dots (CDs), achieving precise enhancement of their photoluminescence (PL) performance without altering the emission wavelength and color remains a challenge. In this work, a deuterated CD is first achieved by simply replacing the reaction solvent from H2O to D2O. The substitution of D atoms for H atoms is not limited on the surface but also within the internal structure of CDs. Deuteration affects the formation of the π-conjugated network structure by altering the content of sp2 carbon and sp3 carbon, ultimately inducing a reconstruction for energy level structure of CDs. Both the intrinsic state and surface state emission, including quantum yield, emission intensity and lifetime, are significantly enhanced after deuteration. It benefits from the reduction in non-radiative transitions, since the lowered vibrational frequencies of D atoms and optimized local energy level distribution in CDs structure. The deuterated CDs are applied in the fabrication of white-light-emitting diodes to show their application potential. This work provides a highly versatile route for improving and controlling photoluminescence performance of CDs and has opportunities to guide the development of CDs for practical applications.

Intensely bonded high filling bismuth oxide with chloroprene rubber to achieve lead-free flexible materials for γ-rays shielding

Achieving lead-free flexible materials with excellent γ-ray shielding as well as good mechanical properties are of significance to radiation protection safety and wear comfort of wearable articles. In this paper, polydopamine (PDA) is coated on Bi2O3 particles to form a typical core–shell structure Bi2O3@PDA, which is used to intensely bond bismuth oxide (Bi2O3) with chloroprene rubber (CR). It promotes the interface interaction between Bi2O3 and CR matrix, leading to the uniform dispersion of the filler and rich interfacial compatibility in CR/Bi2O3@PDA composite with as high as 50 wt% filling. Furthermore, 50 wt% CR/Bi2O3@PDA composite displays 53.6% shielding rate for 105 keV γ-rays. Meanwhile, its tensile strength and elongation at break are 9.6 MPa and 1424.8%, respectively, which are without sacrificing too much in comparison with the neat rubber. We propose a versatile route to prepare superior integrated properties of flexible materials, which can be used as wearable articles for radiation shielding.