Multicomponent synthesis and designing of tetrasubstituted imidazole compounds catalyzed via ionic-liquid for acid steel corrosion protection:Experimental exploration and theoretical calculations

Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established by spectral tools and their purities were verified using thin-layer chromatography(TLC), displaying single-spot. The performance of corrosion protection of the prepared imidazole derivatives was examined theoretically and practically for acid steel corrosion. The experimental study was conducted by electrochemical(electrochemical impedance spectroscopy(EIS) and Tafel polarization(PPS)) tools.The findings from the used approaches concluded that the synthesized compounds were wellorganized inhibitors with an efficiency of 90.7%-98.5% at 50℃ and 0.7 mmol·L^(-1). The Tafel polarization results indicate the protective action of the additives was under mixed-monitoring. The additive adsorption on the electrode interface performed as a distinguished aspect for protection. The surface exploration on the blank and protected metal was completed by field emission scanning electron microscopy(FESEM). Computational studies by Monte Carlo(MC) simulation and quantum chemical calculation(DFT)were related to practical findings. The corrosion protection adsorption mechanism was reinforced by the preferable fitted Langmuir isotherm model. All findings from the applied-inspected approaches alternately confirm each other.

Electronic Properties of Nanopore Edges of Ferromagnetic Graphene Nanomeshes at High Carrier Densities under Ionic-Liquid Gating

Graphene edges with a zigzag-type atomic structure can theoretically produce spontaneous spin polarization despite being a critical-metal-free material. We have demonstrated this in graphene nanomeshes (GNMs) with honeycomb-like arrays of low-defect hexagonal nanopores by observing room-temperature ferromagnetism and spin-based phenomena arising from the zigzag-pore edges. Here, we apply extremely high electric fields to the ferromagnetic (FM) GNMs using an ionic-liquid gate. A large on/off-ratio for hole current is observed for even small applied ionic-liquid gate voltages (Vig). Observations of the magnetoresistance behavior reveal high carrier densities of ~1013 cm-2 at large Vig values. We find a maximum conductance peak in the high -Vig region and its separation into two peaks upon applying a side-gate (in-plane external) voltage (Vex). It is discussed that localized edge-π band with excess-density electrons induced by Vig and its spin splitting for majority and minority of spins by Vex (half-metallicity model) lead to these phenomena. The results must realize critical-element-free novel spintronic devices.

A Stable Polyoxometalate-based Coordination Polymer for Light Driven Degradation of Organic Dye Pollutant

A new POM-based coordination polymer,[Cl_(2)Cu^(Ⅰ)_(11)(trz)_(8)][H_(3)SiW_(12)O_(40)](1),was successfully obtained under hydrothermal reaction.The compound was characterized by single-crystal X-ray diffraction,TGanalyses,IR spectra and PXRD analysis.Compound 1 shows extreme stability and outstanding catalytic activity to the degradation of organic dye pollutant.

Straightforward construction of hollow polyoxometalate-based metal-organic framework via pseudo-homoepitaxial growth

Hollow structures are significant for shortening diffusion path and promoting active center exposure.Single-crystalline hollow polyoxometalate-based metal-organic frameworks(POM@MOFs)with increased adsorption performance and catalytic activity were synthesized through a straightforward pseudo-homoepitaxial growth strategy within only 1.5 min.The strategy ingeniously exploits favorable characteristics of well-matched lattice/structure but acid stability difference between MOF and POM@MOF to construct a pseudo-homoepitaxial structure.Specifically,the MOF single crystals are used as seeds to perform epitaxial growth of the lattice/structure-matched POM@MOF under appropriate conditions.Interestingly,the MOF seeds collapse spontaneously during epitaxial growth,affording regular hollow POM@MOF single crystals.Because the acid stability of the POM@MOF is much higher than that of the MOF,it is speculated that the hollow structure formation may be related to the acid released from the epitaxial POM@MOF growth.And the pseudo-homoepitaxial POM@MOF growth strategy based on structural matching but stability difference avoids additional template removal process in conventional hollow MOF preparation and ensures hollow single crystal construction.

Valorization of Asparagus leafy by-product by ionic-liquid extraction and characterization of bioactive compounds in the extracts

Asparagus(Asparagus officinalis)is a high-value low-calorie vegetable with array of bioactive compounds.Asparagus processing nevertheless generates substantial quantity of by-products;their valorization is of utmost importance for the sustainability of the industry.Here,feasibility of using four imidazolium-based ionic liquids and their combinations as well as water and methanol to extract bioactive compounds from asparagus leafy by-product was investigated.Effectiveness of ultrasound-microwave-assisted heating to augment extraction was also assessed.1-ethyl-3-methylimidazolium-bromide(EMIMBr)resulted in the highest extraction yield of rutin(25.7 mg/g),which is the most abundant compound in the by-product;such a yield was comparable to that achievable via methanol extraction.Ultrasound-microwave-assisted extraction did not show significant improvement in rutin yield when EMIMBr was used.Interestingly,although methanolic extract exhibited slightly higher content of rutin,it also contained the higher number of impurities;EMIMBr extract contained less impurities with higher relative content of rutin(70.9%)than that in methanolic extract(67.7%).This could be a milestone in extraction work for an efficient purification.

Polyoxovanadate-based metal-organic frameworks consisted of open vanadium sites for selective catalytic oxidation of sulfides

Three novel polyoxovanadate-based metal-organic frameworks(POV-MOFs),[Co_(2)(1,4-dtzb)_(3)]{V_(4)O_(12)}(V-Co-MOF_(1),1,4-dtzb=1,4-di(4H-1,2,4-triazol-4-yl)benzene],[Co_(3)(1,3-dtzb)_(2)][{V_(6)O_(18)}(V-Co-MOF_(2),1,3-dtzb=1,3-di(4H-1,2,4-triazol-4-yl)benzene],[Co_(4)(4,4’-bdtzb)_(2)]{V_(8)O_(24)}(V-Co-MOF_(3),4,4’-bdtzb=4,4’-(1,1’-biphenyl)-4,4’-diylbis(4H-1,2,4-triazole)benzene]were facilely synthesized and structurally characterized.Single-crystal X-ray diffraction analysis indicates that all the POV-MOFs possess open V sites lined on POV clusters of{V_(4)O_(12)}/{V_(6)O_(18)}/{V_(8)O_(24)}that uniformly distribute on the robust three-dimensional frameworks.This unique structural feature allows them to show high performance for sulfidesulfoxide transformation when performing the reaction in MeOH at 50℃ for 45 min using H_(2)O_(2) as green oxidant.Notably,V-Co-MOF1 exhibited the highest catalytic efficiency,with a conversion>99% and selectivity up to 97% for a series of sulfide substrates.Control reaction demonstrated the catalytically active centers are the open V sites while the MOF skeleton constructed from Co^(2+)and ligands also contributes to enhance the conversion and selectivity via synergistic effect.Furthermore,V-Co-MOF1 can be used as a stable heterogeneous catalyst,and both the structural integrity and catalytic performance were well reserved after five cycles,demonstrating their great potential for advanced catalytic oxidation.

Polyoxometalate-Incorporated Host-Guest Framework Derived Layered Double Hydroxide Composites for High-Performance Hybrid Supercapacitor

Metal organic frameworks have been employed as high-performance layered double hydroxide(LDH)composite supercapacitor electrode materials but have shown unsatisfactory redox ability and stability.Herein,a host-guest CuMo-based polyoxomet-alate-based metal organic framework(POMOF)with copious electrochemically active sites and strong electrochemical redox activi-ties has been effectively coupled with POM-incorporated CoNi-LDH to develop a nanocomposite(NENU-5@CoNi-LDH)by a simple solvothermal method.The designed electrode shows a high specific capacity of 333.61 mAh·g^(-1) at 1 A·g^(-1).In addition,the novel hy-brid symmetric supercapacitor NENU-5@CoNi-LDH/active carbon(AC)demonstrated a high energy density of 80.8 Wh·kg^(-1) at a power density of 750.7 W·kg^(-1).Interestingly,the nanocomposite of NENU-5@CoNi-LDH exhibits an outstanding capacitance reten-tion of 79%after 5000 charge-discharge cycles at 10 A·g^(-1).This work provides a new strategy and will be the backbone for future energy storage research.

An unprecedented dumbbell-shaped pentadeca-nuclear W-Er heterometal cluster stabilizing nanoscale hexameric arsenotungstate aggregate and electrochemical sensing properties of its conductive hybrid film-modified electrode

Cluster-based functional materials have made remarkable progress owing to their wonderful structures and distinctive physicochemical performances,one of on-going advancements of which is basically driven by synthetic chemistry of exploring and constructing novel nanosized gigantic polyoxometalate(POM)aggregates.In this article,an unprecedented nanoscale hexameric arsenotungstate aggregate Na_(9)K_(16)H_(4)[Er_(0.5)K_(0.5)(H_(2)O)_(7)][Er_(5)W10O_(2)6(H_(2)O)_(14)][B-α-AsW_(9)O_(33)]_(6)·102H_(2)O(1)has been synthesized by the combined synthetic strategy of simultaneously using the arsenotungstate precursor and simple tungstate material in a highly acidic aqueous solution.The{[Er_(5)W_(10)O_(26)(H_(2)O)_(14)][B-α-AsW_(9)O_(33)]6}31-polyanion in 1 consists of an intriguing dumbbell-shaped pentadeca-nuclear W-Er heterometal{Er_(5)W10O_(2)6(H_(2)O)_(14)}^(23+)cluster connecting six trilacunary[B-α-AsW_(9)O_(33)]^(9-)moieties,which has never been seen previously.Furthermore,through electropolymerization of 1 and pyrrole on the conductive substrate,a thickness-controllable and robust 1-PPY(PPY=polypyrrole)hybrid film was successfully prepared,which represents the first POM-PPY film assembled from high-nuclear lanthanide(Ln)encapsulated POM and PPY hitherto.The 1-PPY film-based electrochemical biosensor exhibits a favorable recognition performance for ochratoxin A in multiple media.This work not only provides a feasible combined synthetic strategy of the POM precursor and simple tungstate material for constructing complicated multi-Ln-inserted POM aggregates,but also offers a promising electrochemical platform constructed from POM-based conductive films for identifying trace biomolecules in complex environments.

Highly luminescent ZnO and CdS nanostructures prepared by ionic liquid precursors

The ionic liquids containing Cd and Zn,which served as the metal-chalcogenides precursors,were synthesized and reacted with Na2S to synthesize the ionic-liquid-capped semiconductors. The products were detected by XRD and TEM. The results demonstrated that the CdS was composed of 5―6 nm monodispersed nanocrystals. At the same time,the ZnO composed of 1 μm hexagonal-disk nanostructure was prepared under the same experimental condition. The difference of the morphology and structures between Zn and Cd systems was discussed by thermodynamics and crystallography. The fluorescence of as-prepared ZnO and CdS showed the excellent photoluminescence.