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Abstract: In this work, we synthesized nano-particles (20–80nm) of Li2MnO3 using the self-combustion reaction and studied the electrochemical activity of electrodes prepared from this nano-material at 30, 45, and 60°C. It was shown that the first Li-extraction from nano-Li2MnO3 occurs at much lower potentials (by 180–360mV) in comparison with micron-sized Li2MnO3 electrodes. This can be associated with the higher surface-to-volume ratio, much shorter the diffusion path and the increased surface concentration of the electrochemically active sites. On the basis of magnetic susceptibility studies of nano-Li2MnO3 we proposed a model of disordered surface layer, containing Mn3+ or Mn2+ ions, both at low spin state, at the surface of these nano-particles. From the results of structural analysis (by X-ray and electron diffraction and vibrational Raman spectroscopy) of galvanostatically cycled nano-Li2MnO3 electrodes in Li-cells we came to a conclusion of partial transition of layered LiMO2 to spinel-type ordering. [Copyright &y& Elsevier]

The Schiff base derivative (Ch-8Q) of chitosan (Ch) and 8-hydroxyquinoline-2-carboxaldehyde (8QCHO) was prepared and fibrous mats were obtained by the electrospinning of Ch-8Q/polylactide (PLA) blend solutions in trifluoroacetic acid (TFA). Complexes of the mats were prepared by immersing them in a solution of CuCl 2 or FeCl 3 . Electron paramagnetic resonance (EPR) analysis was performed to examine the complexation of Cu 2+ (Fe 3+ ) in the Ch-8Q/PLA mats complexes. The morphology of the novel materials and their surface chemical composition were studied by scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The performed microbiological screening demonstrated that in contrast to the neat PLA mats, the Ch-8Q-containing mats and their complexes were able to kill all S. aureus bacteria within 3 h of contact. These fibrous materials had efficiency in suppressing the adhesion of pathogenic bacteria S. aureus . In addition, Ch-8Q/PLA mats and their complexes exerted good anticancer efficacy in vitro against human cervical HeLa cells and human breast MCF-7 cells. The Ch-8Q-containing fibrous materials had no cytotoxicity against non-cancer BALB/c 3T3 mouse fibroblast cells. These properties render the prepared materials promising as wound dressings as well as for application in local cancer treatment.

Combining therapeutic with diagnostic agents (theranostics) can revolutionize the course of malignant diseases. Chemotherapy, hyperthermia, or radiation are used together with diagnostic methods such as magnetic resonance imaging (MRI). In contrast to conventional contrast agents (CAs), which only enable non-specific visualization of tissues and organs, the theranostic probe offers targeted diagnostic imaging and therapy simultaneously., Methods: Novel salinomycin (Sal)-based theranostic probes comprising two different paramagnetic metal ions, gadolinium(III) (Gd(III)) or manganese(II) (Mn(II)), as signal emitting motifs for MRI were synthesized and characterized by elemental analysis, infrared spectral analysis (IR), electroparamagnetic resonance (EPR), thermogravimetry (TG) differential scanning calorimetry (DSC) and electrospray ionization mass spectrometry (ESI-MS). To overcome the water insolubility of the two Sal-complexes, they were loaded into empty bacterial ghosts (BGs) cells as transport devices. The potential of the free and BGs-loaded metal complexes as theranostics was evaluated by in vitro relaxivity measurements in a high-field MR scanner and in cell culture studies., Results: Both the free Sal-complexes (Gd(III) salinomycinate (Sal-Gd(III) and Mn(II) salinomycinate (Sal-Mn(II)) and loaded into BGs demonstrated enhanced cytotoxic efficacy against three human tumor cell lines (A549, SW480, CH1/PA-1) relative to the free salinomycinic acid (Sal-H) and its sodium complex (Sal-Na) applied as controls with IC 50 in a submicromolar concentration range. Moreover, Sal-H, Sal-Gd(III), and Sal-Mn(II) were able to induce perturbations in the cell cycle of treated colorectal and breast human cancer cell lines (SW480 and MCF-7, respectively). The relaxivity ( r 1 ) values of both complexes as well as of the loaded BGs, were higher or comparable to the relaxivity values of the clinically applied contrast agents gadopentetate dimeglumine and gadoteridol., Conclusion: This research is the first assessment that demonstrates the potential of Gd(III) and Mn(II) complexes of Sal as theranostic agents for MRI. Due to the remarkable selectivity and mode of action of Sal as part of the compounds, they could revolutionize cancer therapy and allow for early diagnosis and monitoring of therapeutic follow-up.

All-organic Li-ion batteries appear to be a sustainable and safer alternative to the currently-used Li-ion batteries but their application is still limited due to the lack of organic compounds with high redox potentials toward Li + /Li 0 . Herein, we report a computational design of nickel complexes and coordination polymers that have redox potentials spanning the full voltage range: from the highest, 4.7 V, to the lowest, 0.4 V. The complexes and polymers are modeled by binding low- and high-oxidized Ni ions (i.e., Ni(II) and Ni(IV)) to redox-active para-benzoquinone molecules substituted with carboxyl- and cyano-groups. It is found that both the nickel ions and the quinone-derived ligands are redox-active upon lithiation. The type of Ni coordination also has a bearing on the redox potentials. By combining the complex of Ni(IV) with 2-carboxylato-5-cyano-1,4-benzoquinones as a cathode and Ni(II)-2,5-dicarboxylato-3,6-dicyano-1,4-benzoquinone coordination polymer as an anode, all-organic Li-ion batteries could be assembled, operating at an average voltage exceeding 3.0 V and delivering a capacity of more than 300 mAh/g., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

The veterinary 16-membered macrolide antibiotics tylosin (HTyl, 1a ) and tilmicosin (HTilm, 1b ) react with copper(II) ions in acetone at metal-to-ligand molar ratio of 1:2 to form blue ( 2 ) or green ( 3 ) metal(II) coordination species, containing nitrate or chloride anions, respectively. The complexation processes and the properties of 2 - 3 were studied by an assortment of physicochemical techniques (UV-Vis, EPR, NMR, FTIR, elemental analysis). The experimental data revealed that the main portion of copper(II) ions are bound as neutral EPR-silent dinuclear complexes of composition [Cu 2 (µ-NO 3 ) 2 L 2 ] ( 2a - b ) and [Cu 2 (µ-Cl) 2 Cl 2 (HL) 2 ] ( 3a - b ), containing impurities of EPR-active mono-species [Cu(NO 3 )L] ( 2a' - b' ) and [CuCl 2 (HL)] ( 3a' - b' ). The possible structural variants of the dinuclear- and mono-complexes were modeled by the DFT method, and the computed spectroscopic parameters of the optimized constructs were compared to those measured experimentally. Using such a combined approach, the main coordination unit of the macrolides, involved in the complex formation, was defined to be their mycaminosyl substituent, which acts as a terminal ligand in a bidentate mode through the tertiary nitrogen atom and the oxygen from a deprotonated ( 2 ) or non-dissociated ( 3 ) hydroxyl group, respectively.

The transition to a hydrogen economy requires the development of cost-effective methods for purifying hydrogen from CO. In this study, we explore the possibilities of Cu/ZSM-5 as an adsorbent for this purpose. Samples obtained by cation exchange from aqueous solution (AE) and solid-state exchange with CuCl (SE) were characterized by in situ EPR and FTIR, H 2 -TPR, CO-TPD, etc. The AE samples possess mainly isolated Cu 2+ cations not adsorbing CO. Reduction generates Cu + sites demonstrating different affinity to CO, with the strongest centres desorbing CO at about 350 °C. The SE samples have about twice higher Cu/Al ratios, as one H + is exchanged with one Cu + cation. Although some of the introduced Cu + sites are oxidized to Cu 2+ upon contact with air, they easily recover their original oxidation state after thermal treatment in vacuum or under inert gas stream. In addition, these Cu + centres regenerate at relatively low temperatures. It is important that water does not block the CO adsorption sites because of the formation of Cu + (CO)(H 2 O) x complexes. Dynamic adsorption studies show that Cu/ZSM-5 selectively adsorbs CO in the presence of hydrogen. The results indicate that the SE samples are very perspective materials for purification of H 2 from CO.

This study reports an effective approach to improve dramatically the electrochemical performance of nanosized NaFePO 4 with a maricite structure, which is commonly considered as electrochemically inactive due to the absence of structural channels for alkaline ion mobility. The approach is based on the complete oxidation under mild conditions ( i.e. at low temperatures around 280 °C and traces of oxygen) of the nanosized maricite phase. It is prepared by the phosphate-formate precursor method and is additionally ball-milled with a carbon additive. The oxidation of Fe 2+ proceeds at the nanoscale level within the maricite nanoparticles and causes a massive structural transformation of the maricite phase into a monoclinic NASICON phase Na 3 Fe 2 (PO 4 ) 3 with the preservation of the crystallinity. The oxidized maricite phase exhibits high specific capacities, cycling stability and rate capability when it is used as an electrode in both Na and Li half-cells. The effect of different sodium and lithium electrolytes on the storage performance is investigated as well. It is found that the highest specific capacity (of about 150 mA h g -1 ) is achieved in Li half-cells using the LiPF 6 electrolyte, while in Na half-cells the electrolyte NaFSI/EC:DMC achieves a specific capacity of around 100 mA h g -1 . The rate capability is better in Na half-cells than that in Li half-cells. The mechanism of the reversible intercalation/deintercalation of Na + and Li + ions is studied by ex situ XRD and TEM analyses. The results show that the maricite is an electrochemically inactive phase, but through manipulation including oxidation or amorphization it becomes an active electrode material.

The common approach to modify the thermoelectric activity of oxides is based on the concept of selective metal substitution. Herein, we demonstrate an alternative approach based on the formation of multiphase composites, at which the individual components have distinctions in the electric and thermal conductivities. The proof-of-concept includes the formation of multiphase composites between well-defined thermoelectric Co-based oxides: Ni, Fe co-substituted perovskite, LaCo 0.8 Ni 0.1 Fe 0.1 O 3 (LCO), and misfit layered Ca 3 Co 4 O 9 . The interfacial chemical and electrical properties of composites are probed with the means of SEM, PEEM/XAS, and XPS tools, as well as the magnetic susceptibility measurements. The thermoelectric power of the multiphase composites is evaluated by the dimensionless figure of merit, ZT, calculated from the independently measured electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (λ). It has been demonstrated that the magnitude's electric and thermal conductivities depend more significantly on the composite interfaces than the Seebeck coefficient values. As a result, the highest thermoelectric activity is observed at the composite richer on the perovskite (i.e., ZT = 0.34 at 298 K).

Spinel lithium titanate, Li 4 Ti 5 O 12 (LTO), emerges as a "universal" electrode material for Li-ion batteries and hybrid Li/Na-, Li/Mg-, and Na/Mg-ion batteries functioning on the basis of intercalation. Given that LTO operates in a variety of electrolyte solutions, the main challenge is to understand the reactivity of the LTO surface toward single- and dual-cation electrolytes at the molecular level. This study first reports results on ion desolvation and electrolyte solvent/salt degradation on an LTO surface by means of periodic DFT calculations. The desolvation stages are modeled by the adsorption of mono- and binuclear complexes of Li + , Na + , and Mg 2+ with a limited number of ethylene carbonate (EC) solvent molecules on the oxygen-terminated LTO (111) surface, taking into account the presence of a PF 6 - counterion. Alongside cation adsorption, several degradation reactions are discussed: surface-catalyzed dehydrogenation of EC molecules, simultaneous dehydrogenation and fluorination of EC, and Mg 2+ -induced decay of PF 6 - to PF 5 and F - . Data analysis allows the rationalization of existing experimentally established phenomena such as gassing and fluoride deposition. Among the three investigated cations, Mg 2+ is adsorbed most tightly and is predicted to form a thicker fluoride-containing film on the LTO surface. Gassing, characteristic for carbonate-based electrolytes with LTO electrodes, is foreseen to be suppressed in dual-cation batteries. The latter bears promise to outperform the single-ion ones in terms of durability and safety., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

To double the energy density of lithium- and sodium-ion batteries there is a need to activate simultaneously cationic and anionic redox reactions at the intercalation-type electrodes. In contrast to the cationic redox activity, the oxygen redox activity enforces an enhancement in the surface reactivity of the oxides leading to their poor reversibility and cycling stability. Herein, we propose a new concept to stabilize oxygen redox activity by using oxygen-storage materials as an efficient buffer supplying and receiving oxygen during alkali ion intercalation. As a proof-of-concept, the study is focused on CeO 2 as a modifier of sodium nickel-manganese oxide with a three-layer sequence, P 3-Na 2/3 Ni 1/2 Mn 1/2 O 2 . The CeO 2 -modified P 3-Na 2/3 Ni 1/2 Mn 1/2 O 2 displays a drastic increase in the reversible capacity following the order Na + intercalation < Li + intercalation < Li + ,Na + cointercalation.

Novel poly(vinyl alcohol) (PVA)/chitosan (Ch)-based fibrous materials containing an ionizable model drug, 8-hydroxyquinoline-5-sulfonic acid (SQ), were successfully fabricated by electrospinning. Complexes between the components of the crosslinked PVA/Ch/SQ mats and Cu 2+ and Fe 3+ ions were formed. The coordination of these ions in the mats was examined by electron paramagnetic resonance spectroscopy (EPR). The microbiological screening against S. aureus and C. albicans revealed that both the incorporation of SQ in the mats and the complexation with Cu 2+ and Fe 3+ imparted to these materials antibacterial and antifungal activities. Moreover, the SQ-containing mats and their complexes displayed good cytotoxicity against human cervical HeLa tumor cells. The most prominent was the cytotoxicity of the Cu 2+ complex of the mats. The combined antibacterial, antifungal and in vitro antitumor activities render these novel materials promising candidates for wound dressing applications and for application in the local treatment of cervical tumors.

The construction of hybrid metal-ion batteries faces a plethora of challenges. A critical one is to unveil the solvation/desolvation processes at the molecular level in electrolytes that ensure efficient transfer of several types of charge carriers. This study reports first results on simulations of mixed-ion electrolytes. All combinations of homo- and hetero-binuclear complexes of Li + , Na + and Mg 2+ , solvated with varying number of ethylene carbonate (EC) molecules are modeled in non-polar and polar environment by means of first principles calculations and compared to the mononuclear analogues in terms of stability, spatial organization, charge distribution and solvation/desolvation behavior. The used PF 6 - counterion is shown to have minor impact on the geometry of the complexes. The desolvation energy penalty of binuclear complexes can be lowered by the fluoride ions, emerging upon the PF 6 - decay. These model investigations could be extended to rationalize the solvation structure and ionic mobility in dual-ion electrolytes., (© 2021 Wiley-VCH GmbH.)

Hybrid metal ion batteries are perceived as competitive alternatives to lithium ion batteries because they provide better balance between energy/power density, battery cost, and environmental requirements. However, their cycling stability and high-temperature storage performance are still far from the desired. Herein, we first examine the temperature-induced reactivity of three-layered oxide, P 3-Na 2/3 Ni 1/3 Mg 1/6 Mn 1/2 O 2 , toward lithium ionic liquid electrolyte upon cycling in hybrid Li/Na ion cells. Through ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses, the structural and surface changes in P 3-Na 2/3 Ni 1/3 Mg 1/6 Mn 1/2 O 2 are monitored and discussed. Understanding the relevant changes occurring during dual Li + and Na + intercalation into P 3-Na 2/3 Ni 1/3 Mg 1/6 Mn 1/2 O 2 is of crucial importance to enhance the overall performance of hybrid Li/Na ion batteries at elevated temperatures., (Copyright © 2020 Kalapsazova, Kostov, Zhecheva and Stoyanova.)

Novel fibrous materials from polylactide (PLA) and Schiff base from Jeffamine ED® and 8-hydroxyquinoline-2-carboxaldehyde (Jeff-8Q) or its complex with Cu 2+ (Jeff-8Q.Cu 2+ ) were successfully prepared by using one-pot electrospinning or electrospinning combined with dip-coating. These approaches enabled the fabrication of materials of diverse design: non-woven textile in which Jeff-8Q or Jeff-8Q.Cu 2+ was predominantly in the fibers' bulk (type "in") or was deposited as a thin film on the surface of the fibers (type "on"). The morphology of the mats and chemical composition of their surface were analyzed by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The coordination of Cu 2+ ions in Jeff-8Q.Cu 2+ /inPLA and Jeff-8Q.Cu 2+ /onPLA mats was examined by electron paramagnetic resonance (EPR) spectroscopy. It was found that the in vitro release of Jeff-8Q (Jeff-8Q.Cu 2+ ) from the type "on" mats was more rapid than that of the type "in" mats. Enhancement of the antioxidant activity of the Jeff-8Q.Cu 2+ -containing fibrous mats as compared to mats containing Jeff-8Q was observed. In contrast to the neat PLA mat, the Jeff-8Q- and Jeff-8Q.Cu 2+ -containing mats (both type "in" and "on") displayed high in vitro antitumor activity against human cervical HeLa cells. The obtained materials are promising for use in local tumor treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Two new copper complexes of hyperbranched polymers modified with dansyl units were synthesized and characterized by infrared spectroscopy (IR) and electron paramagnetic resonance (EPR) techniques. It was found that copper ions coordinate predominantly with nitrogen or oxygen atoms of the polymer molecule. The place of the formation of complexes and the number of copper ions involved depend on the chemical structure of the polymer. The antimicrobial activity of the new polymers and their Cu(II) complexes was tested against Gram-negative and Gram-positive bacterial and fungal strains. Copper complexes were found to have activity better than that of the corresponding ligands. The deposition of the modified branched polymers onto cotton fabrics prevents the formation of bacterial biofilms, which indicates that the studied polymers can find application in antibacterial textiles.

Sodium manganese phospho-olivine, NaMnPO 4 , is considered to be a higher-voltage alternative to the presently used iron-based electrode material, NaFePO 4 , for sodium ion batteries. Irrespective of this advantage, the electrochemical performance of NaMnPO 4 is still far from what is desired. Herein we provide the first report on the storage performance of NaMnPO 4 having a structure modified by Mg 2+ substitution. The Mg-substituted phospho-olivines are prepared on the basis of ionic exchange reactions involving the participation of Mg-substituted KMnPO 4 ·H 2 O dittmarites as structural template. Furthermore, the phosphate particles were covered with a thin layer (up to 5 nm) of activated carbon through ball-milling. The storage performance of phospho-olivines is analyzed in sodium and lithium half-ion cells, as well as in full-ion cells versus bio-mass derived activated carbon and spinel Li 4 Ti 5 O 12 as anodes. The compatibility of phospho-olivines with electrolytes is assessed by utilization of several types of lithium and sodium carbonate-based solutions. In sodium half-cell, the Mg-substituted phosphate displays a multi-phase mechanism of Na + intercalation in case when NaTFSI-based electrolyte is used. In lithium half-cell, the high specific capacity and rate capability is achieved for phospho-olivine cycled in LiPF 6 -based electrolyte. This is a consequence of the occurrence of dual Li + ,Na + intercalation, which encompass nano-sized domains. The utilization of the Mg-substituted phospho-olivine in the full ion cell is demonstrated., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The present work explores in detail the effect of alkaline-basic electrolytes on the capacitance performance of biomass-derived carbonaceous materials used as electrodes in symmetric supercapacitors. The proof-of-concept is demonstrated by two commercial carbon products (YP-50F and YP-80F, Kuraray Europe GmbH, Vantaa, Finland), obtained from coconuts. The capacitance performance of YP-50F and YP-80F was evaluated in three types of basic electrolytes: 6 M LiOH, 6 M NaOH and 6 M KOH. It was found that the capacitance performance of YP-50F improved in the following order: NaOH < LiOH < KOH; Meanwhile, for YP-80F, the order changes to LiOH < NaOH < KOH. After 1000 cycles, the cycling stability of both YP-50F and YP-80F increased in the order NaOH < LiOH < KOH. This order of performance improvement is determined by both the electrolyte conductivity and the interaction between the functional groups of carbonaceous materials and alkaline electrolytes. The reactivity of the functional groups was assessed by postmortem SEM/EDS and X-ray photoelectron spectroscopy (XPS) analyses of the electrodes after prolonged cycling.

A second-generation poly(propylene imine) dendrimer modified with acridine and its Cu(II) complex have been synthesized for the first time. It has been found that two copper ions form complexes with the nitrogen atoms of the dendrimeric core by coordinate bonds. The new compounds have been characterized by nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), fourier-transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. The spectral characteristics of the modified dendrimer have been measured in different organic solvents, and a negative fluorescence solvatochromism has been observed. The antimicrobial activity of the dendrimers has been tested against model pathogenic microorganisms in agar and by broth dilution method. The cotton fabric treated with both dendrimers has been evaluated towards pathogenic microorganisms. The obtained modified cotton fabrics have been shown to hamper bacterial growth and to prevent biofilm formation. Dendrimer cytotoxicity has been investigated in vitro in the model HEp-2 cell line.

Advanced (7)Li MAS NMR technologies and high frequency EPR are combined to identify structural motifs and their relation to electrochemical properties of layered lithium-cobalt-nickel-manganese oxides LiCo1-2xNixMnxO2 (0 < x ≤ 0.5) used as cathode materials in lithium ion batteries. Structural-chemical shift regularities were established by systematic variation of the ratio of diamagnetic Co(3+) to paramagnetic Ni/Mn ions with variable valences. While EPR allows identifying the oxidation state of transition metal ions inside the layers, (7)Li NMR probes the local structure of Li with respect to transition metal ions located in two adjacent layers. For assignment of the lithium chemical shifts, we examine first magnetically diluted LiCo1-2xNixMnxO2 with x = 0.02, where paramagnetic ions are stabilized only in Mn(4+) and Ni(3+) form. Then the studies are extended towards the intermediate compositions with x = 0.10 and 0.33, containing simultaneously paramagnetic Mn(4+), Ni(3+) and Ni(2+) ions and diamagnetic Co(3+) ions. The benefit of using NMR with ultrafast spinning rates is demonstrated for the end composition LiNi0.5Mn0.5O2 having only paramagnetic Ni(2+) and Mn(2+) ions. The local structure of Li is quantified in respect of the number of Ni(2+) and Mn(4+) neighbors. It has been demonstrated that Ni(2+) and Mn(4+) are non-randomly distributed around Li and their distribution depends on the method of synthesis. The extent of local cationic order and its effect on the electrochemical properties of LiNi0.5Mn0.5O2 are discussed.