Search

The search for appropriate structural correlations in molecule-based crystalline salts is of paramount importance to obtain new advanced multifuctional materials with higher performance in nanoscience and nanotechnology. In this article, we focus on the structural features and bonding interactions in the related family of optical- and electroactive molecular salts of anionic mononuclear bis(dithiooxalato)nickel(II), palladium(II), platinum(II), copper(II), copper(III), and zinc(II) complexes with several uni- and divalent, either inorganic or organic countercations. Steric and/or electronic effects of the metal ion and the inorganic or organic countercation determine the molecular structure and conformation of the resulting bis(dithiooxalato)metalate complex anion in the solid state, concerning both the metal coordination environment and the ligand skeleton, twisting and folding along this family of molecular salts. [ABSTRACT FROM AUTHOR]

Azulene-1,3-bis(semicarbazone), 1, and azulene-1,3-bis(thiosemicarbazone), 2, were synthesized by the acid-catalyzed condensation reactions of semicarbazide and thiosemicarbazide, respectively, with azulene-1,3-dicarboxaldehyde in stoichiometric amounts. Compounds 1 and 2 were identified by high-resolution mass spectrometry and characterized by IR, 1H-NMR, 13C-NMR, and UV-vis spectroscopic techniques. Crystal structure determination of azulene-1,3-bis(thiosemicarbazone) shows that the thiosemicarbazone units exhibit a syn-closed conformation, with both arms oriented in the same direction and adopting an E configuration with respect to the imine linkages. Both hydrazones are redox active and showed fluorescence emission at 450 nm upon excitation at 350 nm. The bis-semicarbazone showed no affinity for anions nor for mercury(II) metal cation. Instead, the bis-thiosemicarbazone showed a lower affinity for chloride anions, but enhanced affinity for binding/poisoning Hg2+ ions. Both compounds were tested against osteosarcoma MG63 cell lines, exhibiting low antiproliferative activity with comparable IC50 values of 473.08 μM and 472.40 μM for compounds 1 and 2, respectively. Despite this limited antiproliferative effect, further analysis using propidium iodide staining revealed a concentration-dependent decrease in cell viability, with high concentrations inducing a marked reduction in cell number, accompanied by morphological changes characteristic of apoptosis and necrosis. [ABSTRACT FROM AUTHOR]

Abstract To address the challenge of reusing foaming agents in foam drainage gas production processes, we developed a redox-responsive surfactant with a straightforward preparation method based on molecular electrostatic interaction assembly. The redox response mechanism of the surfactant was investigated through surface tension, absorbance, particle size, and Zeta potential analyses. Results indicate that the minimum surface tension in the oxidized state can reach 26.4 mN∙m-1, and even after 6 repetitions, it remains at 28 mN∙m-1. In the oxidized state, the surfactant’s particle size can reach 310 nm, effectively stabilizing foam by reducing the liquid discharge rate of the liquid film through large micelles. Moreover, oxidized surfactants exhibit excellent dispersion and stability properties, with a Zeta potential of 28.7 mV. Even after 6 repetitions, the Zeta potential remains above 27.1 mV. Foaming performance tests demonstrate that the oxidation-reduction surfactant exhibits favorable foaming, stabilizing, and reusing effects. At 90 ℃, the initial and 5-minute foaming heights reached 131 mm and 94 mm, respectively. After 6 repetitions, these heights were 124 mm and 85 mm, respectively. The successful development of this treatment agent can effectively address on-site foam drainage needs and reduce the operational costs associated with foam drainage.

Among optimization strategies for solving the poor ion transport ability and electrolyte/electrode interface compatibility problems of lithium (Li)‐based batteries, halogen elements, such as fluorine (F) and iodine (I), have gradually occupied an important position because of their superb electronegativity, oxidizability, ionic radius, and other properties. The study commences by outlining the shared mechanism by which F and I enhance solid‐state lithium metal batteries' electrochemical performance. In particular, F and I can considerably improve ion transport capacity through chemical means such as intermolecular interactions and halogenation reactions. Furthermore, the utilization of F and I significantly enhances the stability of the electrolyte/electrode interface via physical strategies, encompassing doping techniques, the application of surface coatings, and the fabrication of synthetic intermediate layers. Subsequently, the characteristics of F and I used in Li‐based batteries are elaborated in detail, focusing on the fact that F can provide additional energy density as an anode material but by different mechanisms. Additionally, I can considerably activate dead lithium at the negative electrode, and F can act as a new carrier. Finally, a rational concept of the synergistic effect of F and I is proposed and the feasibility of F–I bihalide solid electrolytes is explored. [ABSTRACT FROM AUTHOR]

Three Cp*Co(II)(P−X) (X=N, O) complexes were synthesized using cyclopentadienyl anionic and [P N]/[P O] bidentate ligands. Crystallographic analysis revealed five‐coordinate, 17‐electron unsaturated structures with low‐spin d⁷ Co(II) configurations. Electrochemical studies showed reversible Co(II)/Co(III) redox couples and an irreversible Co(II)/Co(I) process of Cp*Co(II)(P−O) complexes, while complex Cp*Co(II)(P−N) exhibited irreversible Co(II)/Co(III) process due to the pyridine imine ligand. Oxidation with AgBF4 produced stable Co(III) complexes, confirmed by crystallographic data and NMR data. These complexes exhibit significant electrochemical properties and stability, indicating potential for catalytic and organic molecule binding applications. [ABSTRACT FROM AUTHOR]

Cobaltocenium-containing (co)polysiloxanes (Cc-PDMSs) with terminal and side groups were synthesized by the reaction of catalyst-free hydroamination between ethynylcobaltocenium hexafluorophosphate and polysiloxanes comprising amino moieties as terminal and side groups. The conversion of NH2 groups in the polymers reaches 85%. The obtained (co)polysiloxanes "gelate" due to an increase in their molecular weight by approx. 30 times, when stored at room temperature over one week. "Gelated" Cc-PDMSs remain soluble in most polar solvents. The structure of Cc-PDMSs and the mechanism of "gelation" were established by 1H, 13C{1H}, 29Si{1H}, 19F{1H}, 31P{1H} nuclear magnetic resonance, infrared, ultraviolet–visible, and X-ray photoelectron spectroscopies. As determined by cyclic voltammetry, Cc-PDMSs possess redox properties (CoII/CoIII transitions at E1/2 = −1.8 and −1.3 V before and after "gelation", respectively). This synthetic approach allows to increase the molecular weights of the synthesized polysiloxanes functionalized with cobaltocenium groups easily, leading to their higher film-forming ability, which is desirable for some electronic applications. Cc-PDMSs can be utilized as redox-active polymer films in modified electrodes, electrochromic devices, redox-active coatings, and components for batteries. [ABSTRACT FROM AUTHOR]

New manganese(II) and nickel(II) 1-D zigzag coordination polymers [M2+(pQ2−)·2(solv)]n (M2+ = Mn2+, solv = N,N'-dimethylacetamide (1) and M = Ni2+, solv = N,N'-dimethylformamide (2); pQ2− - dianionic form of 2,5-di-hydroxy-3,6-di-tert-butyl-para-quinone) have been synthesized and characterized. Both compounds 1 and 2 are isomorphic. Their physicochemical properties such as thermal stability, gas sorption, redox and magnetic properties are described. [ABSTRACT FROM AUTHOR]

Although the properties of unsubstituted metal tetrapyrroles in solutions have received attention in numerous work, the physico-chemistry of their thin films remains poorly investigated. In this work, we constructed thin films of unsubstituted cobalt phthalocyanine on the surface of quartz plates and indium tin oxide (ITO) electrodes using the Langmuir-Schaefer (LS) and drop casting techniques. In LS films, CoPc species are involved in strong intermolecular interactions, which result in formation of CoPc nanostructures and prominent changes in the ultraviolet-visible spectrum. Electrochemical reduction of CoPc in LS films at −0.9 V (versus silver chloride electrode) results in formation of Co(I) species. In contrast to the highly reactive nature of Co(I)Pc in solution, these species generated in thin films are relatively resistant to dioxygen due to the dense packing of CoPc units. These findings can further the development of CoPc-based resistive sensors utilizing not only common Co(II), but also Co(I) species, which may possess different sensitivity toward analytes. [ABSTRACT FROM AUTHOR]

Azulene-based polycyclic hydrocarbons have garnered much attention as potential materials for organic optoelectronic devices and as molecular models for graphene nanosheets with structural defects. Although various methods for ring fusions to an azulene core have been established for ring fusions to an azulene core, efficient synthetic methodologies for ortho- and peri-fusion to an azulene core are still lacking, which hinders the investigation of the effect of the ortho- and peri-fusion on the electronic properties of the embedded azulene core. Herein, we describe the synthesis and characterization of quinoxaline-fused cyclopenta[cd]azulene 4 as a new ortho- and peri-fused azulene derivative. The target molecule 4 was successfully synthesized in four steps from 4-methylazulene. The ring annulation decreased the lowest excitation energy compared with that of azulene and its structural isomer 5 and led to multiple reversible reduction processes. Characterization of the molecular geometry and optoelectronic properties of 4 revealed that the embedded azulene core preserves its original aromaticity, while the fused quinoxaline acts as a nucleophilic and basic site. These features suggest that 4 could serve as a metal ligand, a near-infrared absorber, and a component in organic functional devices.

Quantifying the active surface area of Mars‐van‐Krevelen catalysts is paramount for the elucidation of structure‐property relationships and the knowledge‐based catalyst development. Different cerium oxides were prepared via precipitation‐based techniques. By altering conditions during precipitation, materials with a wide span of material properties were prepared. The influence of temperature during ammonia‐based precipitation was investigated. When using Ce(IV) precursors an increase in precipitation temperature decreases the crystallite size while increasing specific surface area, attributed to an increase in nucleation rate. Sintering stability is also increased for materials precipitated at higher temperature. Measuring the total oxygen storage capacity (TOSC) values of the prepared materials showed that the TOSC is not strictly a function of BET surface area. Our results suggest that crystallites with a domain size under a certain threshold are not reduced via oxygen release but rather hydroxyl formation. A method was proposed with which the redox active surface area for polycrystalline ceria can be estimated on basis of the domain size obtained from Rietveld refinement. These findings were corroborated by CO oxidation light‐off experiments in which the light‐off temperature was found to correlate with the surface that can release oxygen reversibly, the Mars‐van‐Krevelen active surface area, rather than BET surface area. [ABSTRACT FROM AUTHOR]

Photoelectrode materials with high electron-hole separation efficiency and long-lasting stability are extremely important for photoelectrochemical (PEC) water separation. In this paper, the CdS/PANI composite structure was prepared by a simple hydrothermal method to improve the stability of CdS while maximizing its excellent PEC properties. This system (CdS/PANI) utilizes the redox effect of PANI internal functional groups to accomplish electron-hole migration, which suppresses the photocorrosion of CdS without using any surface sacrificial agent. Meanwhile, the carrier separation is further promoted by the heterojunction structure formed by CdS/PANI under the stimulation of ultrasonic waves. The coordination of the above two effects achieves improved photocatalytic activity and enhanced stability. The electrochemical test results under ultrasonic conditions showed that the PANI composite on CdS increased the photocurrent density (1.23 V vs. RHE) from 1.68 mA/cm−2 to 2.62 mA/cm−2 compared to pure CdS. In addition, the stability of PEC is further enhanced and the photocorrosion rate decreases from 43% to 12%. This strategy provides a promising example for the development of more efficient organic-inorganic piezoelectric photoanode materials. • Design of CdS/PANI materials for the photoelectrochemistry of splitting water. • Enhanced carrier separation and transfer by forming CdS/PANI heterojunctions. • Redox properties of PANI reduce the photocorrosion of CdS promoting photocatalysis. • Piezoelectric effect by CdS stimulates the redox process of PANI. • Synergistic piezoelectric effect and redox promote the photocatalysis of CdS/PANI. [ABSTRACT FROM AUTHOR]

This paper reviews the radiation-induced synthesis of metallic nanostructures and their applications. Radiolysis is a powerful method for synthesizing metallic nanoparticles in solution and heterogeneous media, and it is a clean alternative to other existing physical, chemical, and physicochemical methods. By varying parameters such as the absorbed dose, dose rate, concentrations of metallic precursors, and nature of stabilizing agents, it is possible to control the size, shape, and morphology (alloy, core-shell, etc.) of the nanostructures and, consequently, their properties. Therefore, the as-synthesized nanoparticles have many potential applications in biology, medicine, (photo)catalysis, or energy conversion. [ABSTRACT FROM AUTHOR]

Numerous platinum group metals (PGMs) complexes contain azo-azomethine-based ligands. Azo-azomethine ligands are N-donor ligands that have extended conjugated π-bonded systems and both azo (–N=N–) and aldimine (–C=N–) functions in their structure. Plenty of platinum (Pt) complexes with azo-imine ligands have been prepared and characterized. Various multidentate azo-imine ligands coordinated with different platinum metal substrates afforded structurally diverse platinum chelates. Nonetheless, many azo-imine-based platinum complexes demonstrated a wide range of biological activities, photo-switchable properties, and redox activities. The review encompasses a general overview of platinum complexes with versatile azo-azomethine ligands, their synthetic protocol, spectroscopic and structural features, chemical reactivity, and multipurpose applications in different areas. [ABSTRACT FROM AUTHOR]

Series of ceria-zirconia (CZ)-based nano-materials with a d50 in the range of 0.2 to 1.3 microns were made using the jar milling, Eiger milling, and steam jet milling (SJM) techniques. The effect of the milling conditions on the morphology and textural properties was studied. High-energy steam jet milling in a quasi-hydrothermal environment (with potential local temperature spikes over 500 °C) significantly impacted the CZ crystal structure by inducing lattice distortions. It was shown that the acquired lattice stress resulted in a significant increase in oxygen mobility, which was manifested by a TPR-H2 Tmax shift from 450–550 to 150–250 °C. CZ materials with fast oxygen mobility are metastable phases, and re-slurring nano-CZ powders in water and impregnation with precious metals had stabilizing effects on fast oxygen mobility. Efficiently enhancing the CZ redox activity milling process took place in the following order: Steam jet milling > Eiger milling > jar milling. [ABSTRACT FROM AUTHOR]

This review presents a description of the available data from the literature on the electrochemical properties of flavonoids. The emphasis has been placed on the mechanism of oxidation processes and an attempt was made to find a general relation between the observed reaction paths and the structure of flavonoids. Regardless of the solvent used, three potential regions related to flavonoid structures are characteristic of the occurrence of their electrochemical oxidation. The potential values depend on the solvent used. In the less positive potential region, flavonoids, which have an ortho dihydroxy moiety, are reversibly oxidized to corresponding o-quinones. The o-quinones, if they possess a C3 hydroxyl group, react with water to form a benzofuranone derivative (II). In the second potential region, (II) is irreversibly oxidized. In this potential region, some flavonoids without an ortho dihydroxy moiety can also be oxidized to the corresponding p-quinone methides. The oxidation of the hydroxyl groups located in ring A, which are not in the ortho position, occurs in the third potential region at the most positive values. Some discrepancies in the reported reaction mechanisms have been indicated, and this is a good starting point for further investigations. [ABSTRACT FROM AUTHOR]

The redox properties of electrode materials play a vital role in electrochemical performance. Fabrication of electrode materials with multiple oxidation species is highly desired for ultrasensitive glucose sensing. Herein, multivalent Cu/Cu2O/CuO/C (Cu/C) nanocomposites were successfully prepared for non-enzymatic glucose sensing by in situ pyrolysis of Cu metal-organic framework (Cu3(BTC)2·3H2O, Cu-BTC) at a critical temperature. Structure characterizations showed that the nanocomposites maintained the original morphology of Cu-BTC crystals and exhibited mesoporous structures. Meanwhile, multiple Cu species containing Cu, Cu2O and CuO were generated simultaneously, which were tightly pinned on the ligand-derived carbon layers. Thus, under the synergistic effect of multivalent Cu species, mesoporous structure and intense interface contact, the sensing platforms based on Cu/C nanocomposites exhibited good glucose detection performance with a wide linear range of 0.005-2.0 mM, ultrasensitivity of 147.65 μA mM-1 cm-2, low detection limit of 6.31 μM (S/N = 3), and favorable anti-interference properties and stability. Especially, the Cu/C sensing platform showed excellent recoveries of glucose when used to monitor glucose in real sample of honey. The good electrochemical activities of Cu/C nanocomposites render them promising candidates for sensors and other applications. [ABSTRACT FROM AUTHOR]

DFT-D3 calculations based on structural X-ray diffraction data obtained for 3-oxo-camphorsulfonyl imine (1), camphorsulfonyl chloride (2) and seven camphor sulfonimines (O2SNC10H13NR, L1−L7), from which L2 (R=4-OHC6H4), L4 (R=4-ClC6H4) and L6 (R=3,5-(CH3)2C6H3) are synthesized and characterized in this work, provide information into the intra- and inter-molecular interactions with concomitant elucidation of the supramolecular arrangement of the compounds. The DFT-D3 calculations performed in small clusters of two or three molecular units reproduce the interactions observed via X-ray analyses, showing that, as a general trend, the structural arrangement of the molecules is driven by electronic rather than by packing parameters. In all compounds, the self-assembly of 3D structures involves the sulfonyl imine group (-NSO2) either to establish hydrogen bonds through oxygen atoms or non-classic oxygen–aliphatic hydrogen or non-bonding interactions (NBIs), which also involve sulfonyl oxygen atoms. Interestingly, the camphor sulfonimine compounds (L2, L3), having protic groups (R=C6H4X:X=OH, L2 or X=NH2, L3) at the aromatic imine substituents (=NR), present an extra π-π stacking, which is absent in the other compounds' aromatic derivatives. The X-ray analysis shows that all the reported camphor sulfonimine compounds display the E configuration with respect to the imine substituent (R). The study of the redox behavior of the compounds by cyclic voltammetry enables insight into the solution properties of the compounds and the rationalization of the molecular interactions that stand in the solid and solution states. Camphor sulfonimine compounds (L) display appropriate binding atoms to coordinate transition metals. The results herein show that monodentate coordination through the nitrogen atom of the sulfonimine five-membered ring to the {Ag(NO3)} metal center is favored. When this imine nitrogen atom is not itself involved in the organic framework, DFT-D3 calculations show that the complexation does not affect the non-covalent interactions that are reproduced in the MOF structure. [ABSTRACT FROM AUTHOR]

Amphotericin B is the oldest antifungal molecule which is still currently widely used in clinical practice, in particular for the treatment of invasive diseases, even though it is not devoid of side effects (particularly nephrotoxicity). Recently, its redox properties (i.e., both prooxidant and antioxidant) have been highlighted in the literature as mechanisms involved in both its activity and its toxicity. Interestingly, similar properties can be described for inorganic nanoparticles. In the first part of the present review, the redox properties of Amphotericin B and inorganic nanoparticles are discussed. Then, in the second part, inorganic nanoparticles as carriers of the drug are described. A special emphasis is given to their combined redox properties acting either as a prooxidant or as an antioxidant and their connection to the activity against pathogens (i.e., fungi, parasites, and yeasts) and to their toxicity. In a majority of the published studies, inorganic nanoparticles carrying Amphotericin B are described as having a synergistic activity directly related to the rupture of the redox homeostasis of the pathogen. Due to the unique properties of inorganic nanoparticles (e.g., magnetism, intrinsic anti-infectious properties, stimuli-triggered responses, etc.), these nanomaterials may represent a new generation of medicine that can synergistically enhance the antimicrobial properties of Amphotericin B. [ABSTRACT FROM AUTHOR]

The results of investigation of the optical and electrochemical properties of substituted phthalimides linked to a cymantrenyl moiety by IR and NMR spectroscopy, UV-Vis spectroscopy, and cyclic voltammetry and also by DFT calculations are presented. It was shown that the optical, donor-acceptor, and redox properties of the organometallic phthalimides are affected by substituents in position 1 of the side chain of the cymantrene Cp and in position 4 of the phthalimide benzene ring. The reactions of dicarbonyl chelates with external ligands in the dark attest to hemilability of the Mn–O=C(imide) bond. [ABSTRACT FROM AUTHOR]

In order to investigate the redox properties of extracellular polymeric substances (EPS) in activated sludge extracted by different methods, four typical methods (heating, ultrasonication, EDTA and formaldehyde-NaOH methods) were used to extract EPS of activated sludge and analyzed its components and redox properties, respectively. The results showed that the highest EPS content was obtained by formaldehyde-NaOH method, reaching 68. 59 mg·gg-1, followed by EDTA method(23. 40 mg·gg-1), heating method(18. 2 mg·gg-1) and ultrasonication method(4. 07 mg·gg-1). The extraction efficiency of redox substances in EPS by chemical methods (formaldehyde-NaOH and EDTA methods) was higher than that by physical methods (heating and ultrasonication methods). The electron accepting capacity and electron donating capacity of EPS extracted by different methods were 0. 07～0. 30 μmole-·gg-1 and 0. 01～0. 04 μmole-·gg-1, respectively, among which the electron accepting capacity and electron donating capacity of EPS extracted by EDTA method were the highest. The UV-Vis and FTIR spectra showed the existence of humic substances in EPS, and the content extracted by chemical extraction was higher than that by physical method. The three-dimensional fluorescence spectra showed the fluorescence peaks of protein and humic acid, the protein peak fluorescence intensity of EPS extracted by heating method was higher, while the humic acid peak fluorescence intensity of EPS extracted by chemical method was higher. [ABSTRACT FROM AUTHOR]

DFT is used to study thermodynamic aspects of the mechanism of the electrocatalytic formation of molecular hydrogen using N-methyl-2,4,6-triphenylpyridinyl cations. A structural and energetic analysis of the corresponding intermediate products is performed. It is shown that electrocatalytic formation proceeds through a stage of forming C2-protonated radical cations and their subsequent reduction. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and characterization of a new class of hybrid Wells–Dawson polyoxometalate (POM) containing a diphosphoryl group (P2O6X) of the general formula [P2W17O57(P2O6X)]6− (X=O, NH, or CR1R2). Modifying the bridging unit X was found to impact the redox potentials of the POM. The ease with which a range of α‐functionalized diphosphonic acids (X=CR1R2) can be prepared provides possibilities to access diverse functionalized hybrid POMs. Compared to existing phosphonate hybrid Wells–Dawson POMs, diphosphoryl‐substituted POMs offer a wider tunable redox window and enhanced hydrolytic stability. This study provides a basis for the rational design and synthesis of next‐generation hybrid Wells–Dawson POMs. [ABSTRACT FROM AUTHOR]

Understanding and enhancing the activity of heterogeneous single‐atom catalysts (SACs) are indispensable aspects to use them in industrial applications. Among these, low‐temperature CO oxidation is considered as a model reaction for testing a wide‐range of oxidation catalysts, and as an essential process for the exhaust aftertreatment in modern combustion engines. This study demonstrates that the activity of heterogeneous Cu/CeO2−TiO2 SAC catalysts can be fine‐tuned by controlling the Ce/Ti ratio in CeO2−TiO2 supports, with the highest catalytic activity achieved for a Ce/Ti molar ratio of 0.18. Based on DRIFT, EEL, and EPR spectroscopies, together with high‐resolution electron microscopy and H2‐TPR measurements, it is inferred that the optimized Ce/Ti ratio correlates with i) highest dispersion of separate CeO2 particles on TiO2 surface, ii) more facile reduction of Ce4+ to Ce3+, and iii) enhanced formation of −Cu2+−O−Ce4+−⇆−Cu+−□−Ce3+− redox shuttles, which play a dual role for CO adsorption and O2‐activation. These results extend the understanding of heterogeneous metal single‐atom catalysts and constitute a robust approach for the rational control of their catalytic performance in technically relevant applications. [ABSTRACT FROM AUTHOR]

Catalytic oxidation of CH4 over nonprecious Ni/CeO2 catalysts has attracted wide attention. Controlling the morphology of a CeO2 support can enhance the CH4 oxidation activity without changing the catalyst composition. Herein, a series of 2 wt % Ni/CeO2 nanocatalysts with different CeO2 support morphologies (nanoparticles (P), rods (R), cubes (C)) and synthetic procedures (precipitation, sol-gel (SG)) were evaluated for their CH4 oxidation performance. The redox properties of CeO2 supports and corresponding Ni loaded catalysts were characterized by H2-temperature-programmed reduction and oxygen storage capacity (OSC) measurements. The relationship among the CeO2 morphologies, surface areas, redox properties, and CH4 oxidation activity for both CeO2 supports and Ni/CeO2 catalysts was established. The findings suggest that CeO2-R has a greater amount of surface oxygen vacancies as well as an improved OSC and CH4 oxidation activity compared to CeO2-P and CeO2-C supports. The same CH4 oxidation activity pattern was observed for the Ni containing catalysts (Ni/CeO2-R > Ni/CeO2-P > Ni/CeO2-C). Increasing the CeO2 surface area by using a sol-gel synthesis method (CeO2-SG) improved the amount of surface oxygen vacancies and CH4 oxidation performance of CeO2-SG and Ni/CeO2-SG compared to CeO2-R and Ni/CeO2-R, respectively. Finally, all studied Ni/CeO2 nanocatalysts showed improved hydrothermal stability compared to conventional Pd/Al2O3. [ABSTRACT FROM AUTHOR]

The straightforward access to a new class of aza‐polyaromatics is reported. Starting from readily available fluorinated s‐tetrazine, a cyclization process with azide leads to the formation of an unprecedented tetrazo[1,2‐b]indazole or a bis‐tetrazo[1,2‐b]indazole (cis and trans conformers). Based on the new nitrogen core, further N‐directed palladium‐catalyzed ortho‐C−H bond functionalization allows the introduction of halides or acetates. The physicochemical properties of these compounds were studied by a joint experimental/theoretical approach. The tetrazo[1,2‐b]indazoles display solid‐state π‐stacking, low reduction potential, absorption in the visible range up to the near‐infrared, and intense fluorescence, depending on the molecular structure. [ABSTRACT FROM AUTHOR]

The (D–π)2-type fluorescent dye OTT-2 with two (diphenylamino)carbazole-thiophene units as D (electron-donating group)–π (π-conjugated bridge) moiety and the (D–π)2Ph-type fluorescent dye OTK-2 with the two D–π moieties connected through a phenyl ring were derived by oxidative homocoupling of a stannyl D–π unit and Stille coupling of a stannyl D–π unit with 1,3-diiodobenzene, respectively. Their optical and electrochemical properties were investigated by photoabsorption and fluorescence spectroscopy, time-resolved fluorescence spectroscopy, cyclic voltammetry (CV) and molecular orbital (MO) calculations. In toluene the photoabsorption and fluorescence maximum wavelengths (λmax,abs and λmax,fl) of OTT-2 appear in a longer wavelength region than those of OTK-2. The fluorescence quantum yield (Φfl) of OTT-2 is 0.41, which is higher than that (Φfl = 0.36) of OTK-2. In the solid state OTT-2 shows relatively intense fluorescence properties (Φfl-solid = 0.24 nm), compared with OTK-2 (Φfl-solid = 0.15 nm). CV results demonstrated that OTT-2 and OTK-2 exhibit a reversible oxidation wave. Based on photoabsorption, fluorescence spectroscopy and CV for the two dyes, it was found that the lowest unoccupied molecular orbital (LUMO) energy level of OTT-2 is lower than that of OTK-2, but OTT-2 and OTK-2 have comparable highest occupied molecular orbital (HOMO) energy levels. Consequently, this work reveals that compared to the (D–π)2Ph-type structure, the (D–π)2-type structure exhibits not only a bathochromic shift of the photoabsorption band, but also intense fluorescence emission both in solution and the solid state.

• Two POMOFs was synthesized named as CUST-636 and CUST-638. • CUST-636 and CUST-638 show good electrocatalytic redox properties. • (3) 636-GCE and 638-GCE can detect KBrO 3 , KNO 2 , K 2 Cr 2 O 7 and AA. • detection of trace Cr(VI) was conducted. Polyoxometalates (POMs) based metal-organic frameworks (POMOFs) integrate the merits of POMs with excellent redox properties and MOFs with highly ordered porous crystalline structures, which show potential electrochemical applications relying on the synergistic catalytic effect. Here, two new Keggin-type POMOFs [Cd(btbu) 2 (H 2 O) 2 (PMo 12 O 40)] (CUST-636), [Cd(btbu) 2 (H 2 O)(SiW 12 O 40) 0.5 ](CUST-638) are synthesized using flexible ligand of 1,4-bis(1,2,4-triazol-1-yl)butane (abbreviated as btbu) as a ligand by hydrothermal method. PXRD, IR, and TG analysis were carried out on CUST-636 and CUST-638. Then, they were prepared into electrode materials (referred to as 636-GCE and 638-GCE), to explore the electrocatalytic properties. 636-GCE and 638-GCE show good electrocatalytic redox performance against KBrO 3 , KNO 2 , K 2 Cr 2 O 7 and AA. Furthermore, detection of trace Cr(VI) was conducted using electrochemical sensors 636-GCE and 638-GCE. The low detection limits (LODs) of CUST-636 and CUST-638 were 0.32 and 0.45 μM, respectively, which were lower concentrations of Cr(VI) in drinking water than the maximum allowable concentration specified by the World Health Organization (WHO). [ABSTRACT FROM AUTHOR]

• Structure-property relationships of molecular subunits in single benzene fluorophores with redox potentials were established. • There lies a strong correlation between the highly emissive nature and the low oxidation potentials of the SBFs. • Among the different SBFs, benzomorpholines proved to be the most fluorescent and also the most easily oxidizable moieties. • SBFs with pyrazine ring and no donor amine, were only weakly emissive, and underwent facile electrochemical reduction. The present work focuses on investigation of the electrochemical properties of amino terephthalonitrile based single benzene fluorophores (Am-TN-SBFs) and correlating them with their highly emissive characteristics. We already know that the emissive properties of the Am-TN-SBFs could be modulated by altering the position and geometries of the donor and acceptor groups. In order to understand whether the electrochemical properties of these Am-TN-SBFs could also be tuned in the similar manner, redox properties were studied which remained largely unexplored till date. We were able to successfully identify the key structural characteristics responsible for inducing fluorescence in these molecules, while also facilitating the generation of appealingly low electrochemical potentials. We synthesized few benzomorpholino-based SBFs, which proved to be highly emissive and demonstrated remarkably low quasi-reversible oxidation potential. These molecules hold potential for constructing devices tailored for future electroluminescence-based applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of dibenzodioxins containing electron push‐pull groups were synthesized using simple methods and their spectroscopic and redox behavior was studied. Electrochemical experiments were performed to measure the redox potentials of the substituted dibenzodioxins. The role of individual molecular subunits in tweaking the redox potential values was delineated by comparing them with the electrochemical properties of analogous heteroacenes. In many cases, our redox potentials were found to be comparably low with that of many well‐known heteroacenes. [ABSTRACT FROM AUTHOR]

The noncovalent interactions of (5,10,15,20-tetra(4-methylphenyl)porphinato)cobalt(II) (CoTTP) with C60 and 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero[60]pyrrolidine (PyC60) were studied in toluene using absorption and fluorescence titration methods. The self-assembly in the 2:1 complexes (the triads) (C60)2CoTTP and (PyC60)2CoTTP was established. The bonding constants for (C60)2CoTTP and (PyC60)2CoTTP are defined to be (3.47 ± 0.69) × 109 and (1.47 ± 0.28) × 1010 M−2, respectively. 1H NMR, IR spectroscopy, thermogravimetric analysis and cyclic voltammetry data have provided very good support in favor of efficient complex formation in the ground state between fullerenes and CoTTP. PyC60/C60 fluorescence quenching in the PyC60/C60–CoTTP systems was studied and the fluorescence lifetime with various CoTTP additions was determined. The singlet oxygen quantum yield was determined for PyC60 and the intensity decrease in the 1O2 phosphorescence for C60 and PyC60 with the CoTTP addition leading to the low efficiency of intercombination conversion for the formation of the 3C60* triplet excited state was found. Using femtosecond transient absorption measurements in toluene, the photoinduced electron transfer from the CoTTP in the excited singlet state to fullerene moiety was established. Quantum chemical calculations were used for the determination of molecular structure, stability and the HOMO/LUMO energy levels of the triads as well as to predict the localization of frontier orbitals in the triads. [ABSTRACT FROM AUTHOR]

This work presents a study of the redox properties of CeO 2 particles with (FeCeHS) and without (CeHS) Fe 2 O 3 impregnation, as possible innovative catalysts for oxidation and combustion reactions as well as CO 2 activation. The topic, therefore, is part of a broader analysis of environmental catalysis, which aims to reduce the emissions of polluting substances and improve the exploitation of energy resources, with consequent progress in the eco-friendly field. Different laboratory techniques (Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Ultraviolet-Visible (UV-Vis), and Fourier Transform-Infrared (FT-IR) spectroscopies) point out that iron oxide is deposited on the surface of ceria, which maintains its lattice structure, although the particle morphology is slightly changed. Methanol and ethanol adsorption and conversion were evaluated on these catalysts by Temperature Programmed Surface Reaction (TPSR) and by in situ FT-IR spectroscopy of the probe redox properties, evidencing the formation of surface oxidized intermediates and combustion products. The FeCeHS catalyst demonstrates, in our reaction conditions, a good combustion activity in total oxidation of oxygenated molecules, hindering the formation of formaldehyde from methanol and reducing the quantity of CO produced by the partial oxidation reaction. A cooperative effect is suggested by the mixture of these two metals in the oxidation process.

The electrochemical properties of chars have been recently described, positioning chars as active participants in microbial redox processes through functional groups, aromatic structures, redox-active metals, and radicals. While bench-scale studies have advanced mechanistic understanding of char's behavior and potential effects, translating these findings to complex ecosystems remains challenging. This is mainly due to the complexities of microbial communities and the unique properties of various ecosystems. Factors like char aging and patina formation, and environmental parameters including oxygen and moisture availability, pH, and organic matter content can significantly affect char electrochemical properties and microbial interactions. This highlights the need for a broader understanding of char redox processes to predict and effectively manage unintended environmental impacts or enhance beneficial effects. Long-term monitoring of complex systems amended with char is also needed to determine whether char accumulation has long-term redox effects on microbial ecosystem services, including biogeochemical cycling. Predictive understanding of these processes would inform the production of chars to enhance beneficial processes such as increased soil productivity, and provide new opportunities for engineered environmental remediation. Here, we summarize how char redox properties affect well-defined microbial systems and discuss key factors that determine whether the effects of char redox properties are enhanced or attenuated in complex systems. We also identify critical knowledge gaps about chars' role in microbial redox processes that are important for environmental sustainability and postulate that managing char's redox properties, such as electron donating, accepting, or conducting ability, is an emerging opportunity to influence microbial ecosystem services.

Amphotericin B is the oldest antifungal molecule which is still currently widely used in clinical practice, in particular for the treatment of invasive diseases, even though it is not devoid of side effects (particularly nephrotoxicity). Recently, its redox properties (i.e., both prooxidant and antioxidant) have been highlighted in the literature as mechanisms involved in both its activity and its toxicity. Interestingly, similar properties can be described for inorganic nanoparticles. In the first part of the present review, the redox properties of Amphotericin B and inorganic nanoparticles are discussed. Then, in the second part, inorganic nanoparticles as carriers of the drug are described. A special emphasis is given to their combined redox properties acting either as a prooxidant or as an antioxidant and their connection to the activity against pathogens (i.e., fungi, parasites, and yeasts) and to their toxicity. In a majority of the published studies, inorganic nanoparticles carrying Amphotericin B are described as having a synergistic activity directly related to the rupture of the redox homeostasis of the pathogen. Due to the unique properties of inorganic nanoparticles (e.g., magnetism, intrinsic anti-infectious properties, stimuli-triggered responses, etc.), these nanomaterials may represent a new generation of medicine that can synergistically enhance the antimicrobial properties of Amphotericin B.

DFT-D3 calculations based on structural X-ray diffraction data obtained for 3-oxo-camphorsulfonyl imine (1), camphorsulfonyl chloride (2) and seven camphor sulfonimines (O2SNC10H13NR, L1−L7), from which L2 (R=4-OHC6H4), L4 (R=4-ClC6H4) and L6 (R=3,5-(CH3)2C6H3) are synthesized and characterized in this work, provide information into the intra- and inter-molecular interactions with concomitant elucidation of the supramolecular arrangement of the compounds. The DFT-D3 calculations performed in small clusters of two or three molecular units reproduce the interactions observed via X-ray analyses, showing that, as a general trend, the structural arrangement of the molecules is driven by electronic rather than by packing parameters. In all compounds, the self-assembly of 3D structures involves the sulfonyl imine group (-NSO2) either to establish hydrogen bonds through oxygen atoms or non-classic oxygen–aliphatic hydrogen or non-bonding interactions (NBIs), which also involve sulfonyl oxygen atoms. Interestingly, the camphor sulfonimine compounds (L2, L3), having protic groups (R=C6H4X:X=OH, L2 or X=NH2, L3) at the aromatic imine substituents (=NR), present an extra π-π stacking, which is absent in the other compounds’ aromatic derivatives. The X-ray analysis shows that all the reported camphor sulfonimine compounds display the E configuration with respect to the imine substituent (R). The study of the redox behavior of the compounds by cyclic voltammetry enables insight into the solution properties of the compounds and the rationalization of the molecular interactions that stand in the solid and solution states. Camphor sulfonimine compounds (L) display appropriate binding atoms to coordinate transition metals. The results herein show that monodentate coordination through the nitrogen atom of the sulfonimine five-membered ring to the {Ag(NO3)} metal center is favored. When this imine nitrogen atom is not itself involved in the organic framework, DFT-D3 calculations show that the complexation does not affect the non-covalent interactions that are reproduced in the MOF structure.

Utilizing McMurry reactions of 4,4′-dihydroxybenzophenone with appropriate carbonyl compounds, a series of 4-Hydroxytamoxifen analogues were synthesized. Their cytotoxic activity was evaluated in vitro on four human malignant cell lines (MCF-7, MDA-MB 231, A2058, HT-29). It was found that some of these novel Tamoxifen analogues show marked cytotoxicity in a dose-dependent manner. The relative ROS-generating capability of the synthetized analogues was evaluated by cyclic voltammetry (CV) and DFT modeling studies. The results of cell-viability assays, CV measurements and DFT calculations suggest that the cytotoxicity of the majority of the novel compounds is mainly elicited by their interactions with cellular targets including estrogen receptors rather than triggered by redox processes. However, three novel compounds could be involved in ROS-production and subsequent formation of quinone-methide preventing proliferation and disrupting the redox balance of the treated cells. Among the cell lines studied, HT-29 proved to be the most susceptible to the treatment with compounds having ROS-generating potency. [ABSTRACT FROM AUTHOR]

Volatile organic compound (VOC) abatement has become imperative nowadays due to their harmful effect on human health and on the environment. Catalytic oxidation has appeared as an innovative and promising approach, as the pollutants can be totally oxidized at moderate operating temperatures under 500 °C. The most active single oxides in the total oxidation of hydrocarbons have been shown to be manganese and cobalt oxides. The main factors affecting the catalytic performances of several metal-oxide catalysts, including CoOx and MnOx, in relation to the total oxidation of hydrocarbons have been reviewed. The influence of these factors is directly related to the Mars–van Krevelen mechanism, which is known to be applied in the case of the oxidation of VOCs in general and hydrocarbons in particular, using transitional metal oxides as catalysts. The catalytic behaviors of the studied oxides could be closely related to their redox properties, their nonstoichiometric, defective structure, and their lattice oxygen mobility. The control of the structural and textural properties of the studied metal oxides, such as specific surface area and specific morphology, plays an important role in catalytic applications. A fundamental challenge in the development of efficient and low-cost catalysts is to choose the criteria for selecting them. Therefore, this research could be useful for tailoring advanced and high-performance catalysts for the total oxidation of VOCs. [ABSTRACT FROM AUTHOR]

Synthesis of materials in Ni/SrTiO 3 system was undertaken. Perovskite structure material with nominal composition SrTi 0.98 O 3 was synthesised by the sol-gel method. Nickel was introduced into the system by the wet impregnation method followed by proper thermal treatment. Two research paths were carried out: the evaluation of sintering conditions on material properties (sintering temperature: 1100, 1200, 1300 and 1400 °C; sintering time: 1, 3 and 5 h for sintering at 1300 °C) and the effect of nickel addition on the material properties - 1, 2, and 5 mol% of Ni compared to the amount of Ti was introduced into the analysed system. The microstructures of the materials, together with their structural (XRD analysis) and electrical (total conductivity and Seebeck coefficient) properties, were determined. Furthermore, temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPOx) measurements were performed to evaluate the materials' redox properties. It was shown that less than 1 mol% of Ni could be incorporated into the strontium titanate structure when a wet impregnation was chosen as the method for the introduction of Ni into the SrTiO 3 -based system. NiO and, for the highest amount of introduced nickel, also NiTiO 3 were the main additional nickel-containing phases. For all materials synthesised in the Ni/SrTiO 3 system, the positive value of the Seebeck coefficient was observed, suggesting that nickel is an acceptor-type dopant while incorporated into the perovskite structure. However, the TPR measurements clearly imply that nickel can be incorporated into the strontium titanate structure in various oxidation states. [ABSTRACT FROM AUTHOR]

Graphical depiction of LUMOs of cis and trans isomers of VO(acac) 2 pyr complexes in oxidized state, and corresponding SOMOs of the reduced state. [Display omitted] The use of vanadium complexes for potential applications in medicine largely depends on the structural properties of the complex itself, as well as on the electronic configuration of the metal and its oxidation state. When the vanadium complex binds to biomolecules or by binding solvent molecules to the complex, there is a change in the structure but also a change in the redox properties of the complex. Using theoretical methods, especially Density Functional theory (DFT), it is possible to determine which factors influence changes in the redox properties of the complex. Furthermore, by calculating the Electron Paramagnetic Resonance (EPR) constants of hyperfine coupling, it is possible to obtain not only data on the electronic configuration, but also to predict changes in redox properties upon changes in the structure of the complex. DFT results show that the binding of pyridine or imidazole to the VO(acac) 2 complex leads to a lowering of the redox potential. The largest changes in the redox potential were observed in the case when the incoming ligand binds in a cis position relative to the V O bond. [ABSTRACT FROM AUTHOR]

A new binuclear copper(II) complex Cu2(Piv)4(L)2, where Piv– = pivalate, L = 2,6-di-tert-butyl-4-(3,5-bis(4-pyridyl)pyridyl)phenol, was synthesized, and its molecular and crysral structures were determined at temperatures of 160, 173, and 296 K (CIF files CCDC no. 2144104, 2144105, and 2144106, respectively). Cyclic voltammetry measurements revealed three irreversible oxidation processes in the potential range of 0.5–1.2 V versus Fc+/Fc. Analysis of the temperature dependence of the magnetic susceptibility of Cu2(Piv)4(L)2 showed that antiferromagnetic interactions of Cu2+ ions predominate in the complex. It was found that the oxidation of Cu2(Piv)4(L)2 upon grinding with PbO2 or treatment of a solid sample with an aqueous solution of K3[Fe(CN)6] affords long-lived phenoxyl radical, which can be detected by ESR spectroscopy. [ABSTRACT FROM AUTHOR]

Redox properties of bis(1-naphtylimino)acenaphthene have been studied using various voltammetry techniques. Radical anion of diimine ligand has been obtained in situ through electrochemical reduction, and its optical properties have been studied. A new sodium complex having the anion-radical form of bis(1-naphthylimino)-acenaphthene has been obtained and structurally characterized. We have found that the solvent nature affects the long-wavelength absorption band of the sodium complex, which is determined by the contribution of the coordinated solvent molecules to the lowest unoccupied molecular orbital (LUMO) energy. [ABSTRACT FROM AUTHOR]

A combination of different types of redox-active systems in one molecule makes it possible to create coordination compounds with extended redox abilities, combining molecular and electronic structures determined by the features of intra- and intermolecular interactions between such redox-active centres. This review summarizes and analyses information from the literature, published mainly from 2000 to the present, on the methods of preparation, the molecular and electronic structure of mixed-ligand coordination compounds based on redox-active ligands of the o-benzoquinone type and ferrocenes, ferrocene-containing ligands, the features of their redox properties, and some chemical behaviour. [ABSTRACT FROM AUTHOR]