Search

Carbon paste electrodes ex-situ modified with different surfactants were studied using cyclic voltammetry with two model redox couples, namely hexaammineruthenium (II)/(III) and hexacyanoferrate (II)/(III), in 0.1 mol L−1 acetate buffer (pH 4), 0.1 mol L−1 phosphate buffer (pH 7), and 0.1 mol L−1 ammonia buffer (pH 9) at a scan rate ranging from 50 to 500 mV s−1. Distinct effects of pH, ionic strength, and the composition of supporting media, as well as of the amount of surfactant and its accumulation at the electrode surface, could be observed and found reflected in changes of double-layer capacitance and electrode kinetics. It has been proved that, at the two-phase interface, the presence of surfactants results in elctrostatic interactions that dominate in the transfer of model substances, possibly accompanied also by the effect of erosion at the carbon paste surface. The individual findings depend on the configurations investigated, which are also illustrated on numerous schemes of the actual microstructure at the respective electrode surface. Finally, principal observations and results are highlighted and discussed with respect to the future development and possible applications of sensors based on surfactant-modified composited electrodes., Uhlíkové pastové elektrody ex-situ modifikované různými povrchově aktivními látkami byly studovány pomocí cyklické voltametrie se dvěma modelovými redoxními páry, konkrétně hexaammineruthenium (II)/(III) a hexakyanoželezitanem (II)/(III), v 0,1 mol L-1 acetátovém pufru (pH 4), 0,1 mol L-1 fosfátového pufru (pH 7) a 0,1 mol L-1 amoniakálního pufru (pH 9) při rychlosti skenování v rozmezí od 50 do 500 mV s-1. Byly pozorovány zřetelné vlivy pH, iontové síly a složení pracovních médií, stejně jako množství povrchově aktivní látky a její akumulace na povrchu elektrody, které se projevily ve změnách kapacitance elektrodové dvouvrstvy a kinetiky elektrodových reakcí. Bylo prokázáno, že na dvoufázovém rozhraní má přítomnost povrchově aktivních látek za následek elektrostatické interakce, které dominují v přenosu modelových látek, případně doprovázené i efektem eroze na povrchu uhlíkové pasty. Jednotlivá zjištění závisí na zkoumaných konfiguracích, které jsou rovněž znázorněny na četných schématech skutečné mikrostruktury na příslušném povrchu elektrody. Nakonec jsou zdůrazněny a diskutovány hlavní pozorování a výsledky s ohledem na budoucí vývoj a možné aplikace senzorů založených na kompozitních elektrodách modifikovaných povrchově aktivními látkami.

The anticholinergic drug, solifenacin, is frequently used for the treatment of the urological tract for urinary incontinence, and urinary frequency. The development of reliable and effective solifenacin electrochemical sensors is of great importance for the pharmaceutical industry and clinical practice. In this work, the electrochemical behavior of solifenacin succinate (SOL) was studied using three different working electrodes: gold (Au), glassy carbon (GCE) and boron-doped diamond electrode (BDDE). The cyclic voltammetric (CV) measurements performed in 0.05 M NaHCO3 indicated that the SOL oxidation process is irreversible and diffusion-controlled at all investigated working electrodes. Afterwards, the testing of SOL electrochemical stability and the possibility of its electrochemical degradation was performed at the Au electrode by the cycling of the potential during 3 h and continuously to 6 h. It was shown that the SOL was electrochemically transformed into another electroactive species and its degradation was excluded. For electroanalytical application, the anodically pretreated BDDE (+2.0 V; 30 s) was selected. Various experimental parameters were optimized, including the pH of the aqueous Britton-Robinson (B-R) buffer as a supporting electrolyte (from pH 2.0 to 11.98) and the most intensive peak of the target analyte was at pH 11.0, so this pH value was chosen as the optimum for further measurements. Based on the correlation of the SOL peak intensity and different concentrations, the developed differential pulse voltammetric (DPV) method was characterized by a linear concentration range from 0.041 to 2.50 µM, with a correlation coefficient of 0.999, and a relative standard deviation of 0.3 %. Taking into account the sensitivity of the developed DPV method towards the electrochemical oxidation of SOL, a very low detection limit of 0.012 µM in the model system was achieved. The BDDE showed adequate selectivity for SOL in the presence of the investigated interfe

Azobenzenes (ABs) are versatile compounds featured in numerous applications for energy storage systems, such as solar thermal storages or phase change materials. Additionally, the reversible one-electron reduction of these diazenes to the nitrogen-based radical anion has been used in battery applications. Although the oxidation of ABs is normally irreversible, 4,4’-diamino substitution allows a reversible 2e− oxidation, which is attributed to the formation of a stable bis-quinoidal structure. Herein, we present a system that shows a bipolar redox behaviour. In this way, ABs can serve not only as anolytes, but also as catholytes. The resulting redox potentials can be tailored by suitable amine- and ring-substitution. For the first time, the solid-state structure of the oxidized form could be characterized by X-ray diffraction.

The use of sensors in the food industry is essential to determine and preserve the quality of their products. In the food industry, the detection, analysis, quantification, and evaluation of sugars are vital for ensuring and guaranteeing the quality and security of food and beverages. Therefore, a wide variety of electrochemical sensors based on the molecularly imprinted polymer (MIP) technique have caught a lot of attention in detecting sugar. After the design of these sensors, the response can be measured by potentiometric or cyclic voltammetric methods. This investigation uses chitosan as a biopolymer to develop MIP sensors. These sensors detect sugars like glucose and lactose. The MIP layer is deposited in a glassy carbon electrode (GCE). The response of the MIP sensor is evaluated with a non-imprinted polymer (NIP) sensor created by the absence of the templated molecule. To improve the sensor's capabilities, the influence of adding nanoparticles in the development of MIP sensors has been evaluated. Metallic nanoparticles like gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) were used. On the influence of AgNPs, the MIP sensor has a much higher response than the non-modified sensor. The optimized MIP sensor is a viable analytical method for food industrial applications. It detects the presence of sugar in food and raw materials used in food processing., Departamento de Química Física y Química Inorgánica, Máster en Nanociencia y Nanotecnología Molecular

The use of sensors in the food industry is essential to control and guarantee the organoleptic properties of their products. For this purpose, the preparation of sensors to easily measure the different compounds present in food has generated an enormous interest. Molecularly imprinted polymers (MIPs) can act as electrochemical sensors purposely designed to have specific recognition cavities. This cavities are shaped by the use of a definite template molecule present during the formation of the sensor. Once the molecularly imprinted polymer is formed, the template molecule is eluted leaving behind the specific cavities. The presence of this cavities will later be crucial in the selective detection of a specific concentration range of solutions containing the template molecule. In this work, MIP sensors have been developed using the electrodeposition of a biopolymer, chitosan, via cyclic voltammetry in a glassy carbon electrode. The parameters of this electrodeposition have been optimized in this work, modifying mainly the use of cross-linking agent as well as the pH of the chitosan solution. For the optimization, the response of the sensor towards catechol using cyclic voltammetry was evaluated in comparison to the use of a non-imprinted polymer (NIP), prepared under the same conditions but in the absence of template molecule. Also, the effect of introducing metallic nanoparticles has been tested in order to see how they affect the intensity of response of the sensors. In this case gold (AuNPs) and silver (AgNPs) nanoparticles have been used. Once optimized, MIP sensors have been developed to detect organic acids present in the food industry, successfully obtaining sensors for the detection of lactic, malic and tartaric acid. All of the prepared MIP sensors gave a limit of detection in the order of 10-5M or lower in the detection of the compound they were designed for. The addition of nanoparticles, even though it gave positive results, was discarded due to the balan, Departamento de Química Física y Química Inorgánica, Máster en Nanociencia y Nanotecnología Molecular

State-of-the-art liquid electrolytes, composed of flammable organic solvents, pose serious safety risks in lithium- and sodium-ion batteries. Non-flammable liquid electrolytes, particularly those based on phosphate solvents, offer a promising solution. However, they still lack compatibility with the most widely accepted carbonaceous anodes, due to continuous electrolyte decomposition or solvent co-intercalation. This thesis investigates triethyl phosphate (TEP) as a non-flammable electrolyte solvent for both lithium- and sodium-ion batteries. For lithium-ion batteries, an LHCE composed of 1.5 M LiFSI in TEP + diluent was examined. The effect of two diluents, bis(2,2,2-trifluoroethyl) ether (BTFE) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE), on solvation structure and electrochemical performance was investigated. It was shown by Raman and Nuclear Magnetic Resonance (NMR) spectroscopy that addition of both diluents in LHCEs resulted in minor changes in interactions between Li+, TEP and the diluents, while maintaining a similar solvation structure as in high concentration electrolytes. In a lithium-ion full-cell, based on LiNi0.6Mn0.2Co0.2O2 (NMC622) | graphite, LHCEs prevented continuous TEP decomposition and TEP co-intercalation. For sodium-ion batteries, the effects of ethers as co-solvents in TEP, various sodium salts, and several additives were investigated. Co-solvation of TEP with diglyme and tetraglyme using sodium hexafluorophosphate (NaPF6) and sodium tetrafluoroborate (NaBF4) salts revealed a significant trend between ionic conductivity and viscosity. NaPF6-based electrolytes showed higher ionic conductivities than NaBF4-based electrolytes, despite higher viscosity. NMR and computational studies revealed stronger interaction of the BF4 anion with the first solvation shell indicating more ion-ion interactions, leading to lower ionic conductivity. Despite promising fundamental insights in physicochemical properties, glymes were unable t

A novel poly (glutamic acid)-modified graphene carbon paste sensor (PGMGCPS) was developed by the electro-polymerization technique for the analysis of Pyridoxine (PYX). Scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersive X-ray (EDX) and Electrochemical impedance spectroscopy (EIS) were employed to gain a deep insight into the surface modification and elemental analysis of the unmodified graphene carbon paste sensor (UGCPS) and PGMGCPS. The study of the impact of scan rate on the PYX analysis at the PGMGCPS surface revealed that the oxidation process is diffusion-controlled and at an optimum pH of 6.0 of PBS (phosphate buffer solution, 0.2 M), the sensor demonstrated a detection limit (DL) of 0.09 × 10−7 M and 0.35 × 10−6 M through CV and DPV methods, respectively. A probe into the crucial attributes like repeatability, reproducibility, stability and concurrent analysing capacity signified the designed sensor as an efficient electrochemical tool to analyse PYX in food and pharmaceutical samples.

Electrochemical impedance spectroscopy (EIS) is used extensively in battery research, but usually at frequencies that do not reflect real-world usage patterns. This has resulted in equivalent circuit models (ECMs) that are over-complicated, and suboptimal battery management systems. It is logical to measure batteries at frequencies reflecting their daily or weekly charge-discharge cycles, i.e., of the order of microhertz. This is generally not done, however, because of difficulties that include extreme measurement durations and the need for care to avoid issues such as charge distribution problems, charge drift, and the risk of overcharging or flattening the battery. This research demonstrates the feasibility of extra-low frequency (ELF) EIS measurement using standard, non-specialised measurement equipment, and the optimisation of frequency domain data through the superimposition of small-signal measurement tones on larger square wave currents. Study of charge movement rates in the frequency domain and voltage responses in the time domain in batteries indicates connections between voltage sweep rate in cyclic voltammetry (CV) and current magnitude in incremental capacity analysis (ICA). The key factor determining what the investigator sees, e.g., reversibility of electrode processes or evidence of individual electrochemical reactions, is rate of movement of charge. Thus, controlled current can be used to obtain CV-type data from a battery, something that would be hazardous if done conventionally using a voltage ramp. Repeatable, low-error EIS measurements at ELFs are essential for inferring battery ECM components, including constant phase elements (CPEs). The fractional order of a CPE is linked to battery state of health (SoH) and energy efficiency. This thesis shows that efficiency measurements with waveforms representative of real battery usage can be used to track battery SoH accurately.

In this research, each graphene oxide and nano-bentonite was synthesized using the Improved Hummers method and the Sonochemical method for formaldehyde detection by cyclic voltammetry. Formaldehyde detection by cyclic voltammetry has several factors to accurately detect formaldehyde, such as electrode composition, the pH of the solution, the deposition time, and the scan rate. In this study, formaldehyde detection using nano-bentonite modified graphene oxide electrode has the optimum electrode composition in the ratio of graphene oxide: paraffin: nano-bentonite 3:2:5, pH of the optimum solution for detection of formaldehyde 4, 10-second deposition time and scan rate 100 mV/sec. Nano-bentonite modified graphene oxide electrode has a detection limit of up to 0.16856 ppm (0.005613 mM) with a recovery of 99.414%. This sensor was successfully applied for formaldehyde measurement in the actual sample and showed good selectivity, sensitivity, reproducibility, and precision.

Knowledge on reaction kinetics is essential for further understanding electrochemical reactions and the development of electrochemical processes. Different tools are available to study reaction kinetics of redox electrodes. One that is widely used is the rotating disk electrode (RDE). However, RDE has limitations when it comes to more complex electrochemical reactions, especially those involving gas evolution. Due to the facing downwards of the planar electrode surface evolving gas bubbles cannot escape by buoyance leading to temporarily and stochastically insultation. This limits using the RDE to low overpotentials or high rotation rates for these kind of reactions in order to prevent blockage of the electrode surface with gas bubbles. To overcome these limitations, we present a modification for commercially available RDE that is based on rapid prototyping using 3D-printing. This allows the RDE setup to be easily operated in a tilted position allowing the gas bubbles to escape from the electrode surface by buoyance. We validate the tilted RDE setup using the example of the well-studied redox pair ferro-/ferricyanide. This is achieved by calculating the diffusion coefficient for both redox species in straight and tilted position based on the Levich-equation. We show that the presented setup can be further used for more complex reactions.

Rosa canina extracts have traditionally been used in nutrition due to their high vitamin C content and other bioactive substances such as polyphenols. The total antioxidant activity (TAC) of these bioactive components is an important indicator of the product's biological value. While standard spectrophotometric methods have been used to quantify TAC, the use of electrochemical methods offers significant advantages in terms of speed, cost, and sample preparation. This study aims to compare electrochemical and spectrophotometric methods for determining the total antioxidant capacity before and after in vitro digestion of Rosa canina samples. The TAC of dried fruit extract, the liquid phase after digestion, and the solid phase after digestion were determined using cyclic voltammetry, differential pulse voltammetry, and the ABTS spectrophotometric method. All samples for TAC detection were prepared by dissolving in water. The study found that the TAC of the fruit extract was significantly higher compared to samples after digestion, with the liquid phase having higher TAC compared to the solid phase. The results for TAC obtained by cyclic voltammetry and differential pulse voltammetry were in good agreement, while the results obtained by the ABTS method showed slightly lower values for samples after digestion. The time required to obtain the TAC by voltammetry is much shorter, as the analyses only take a few seconds and do not require additional sample treatments as with spectrophotometric methods. Our results provide valuable data guiding us into further research on electrochemical methods for rapid, routine determination of TAC in extracts before and after digestion. Electrochemical techniques can exceed the limits of spectrophotometric analysis, such as lower sensitivity and slower response, and are successfully applied as a replacement for long-running spectrophotometric methods.

Due to their intriguing electronic properties and structural composition, transition metal oxides (TMOs) such as AOx, AxOx, and AxB3-xOx; A, B = Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, W, etc., and their designed composites have tremendous potential in energy storage devices such as supercapacitors (SCs) and metal ion batteries (MIBs). Some outstanding properties of TMOs and their composites for applications as electrode materials in energy storage devices include their high conductivity, charge storage characteristics, doping potential, and composite forming propensity. The significant interactions of TMOs with heteroatoms, conductive polymers, and carbon nanomaterials (CNMs) drastically change the reactive parameters and electrical characteristics. This review covers the most recent advances in TMO research and development, ranging from mechanism design to device performance, with a main focus on essentials such as design, synthesis, manufacturing, and energy-storing properties. The electrochemical pyrolysis, in-situ preparation, solvothermal/hydrothermal approach, and other critical approaches and their implications are also discussed. The synergetic improvement of designed TMO/graphene, TMO/rGO, TMO/heteroatoms, TMO/polymers, TMO/halide/hydride, TMO/Chalcogens through ionic interactions, and investigation of the electrode–electrolyte interfaces have been discussed in detail. In addition, the effect of electrolytes, surface behavior, and performance evaluation parameters on the SC device performance have been included. Furthermore, parameters and models, reliability design and profile lifetime, common mistakes in performance evaluation of SC, and other obstacles and mitigation have been described in depth. Altogether, a well-grasped overview and potential strategies extended from the overall analysis of electrode materials and electrolytes are offered to lift advancement in developing futuristic materials for energy storage applications., Validerad;2023;Nivå 2;2023-10-02 (joosat);Funder: European Union;Full text license: CC BY

We report, for the first time, the thorough electrochemical characterization of zinc aluminate spinel. Four different stoichiometric composition of zinc aluminate (ZnAl1.5O3.25, ZnAl2O4, ZnAl2.87O5.30, and ZnAl4O7) were prepared by solution combustion method. The obtained powders after calcination at 1000 °C were characterized through scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction to analyze the morphology, elemental composition and structure, respectively, of the zinc aluminate compositions. The electrodes were prepared by coating slurry of zinc aluminate, carbon black and polyvinylidene fluoride on nickel foam in a ratio of 8:1:1. The electrochemical characterization was carried out by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). ZnAl1.5O3.25 exhibited the highest specific capacity of 546 C/g at 1 mV/s and 336 C/g at 1 A/g, as appraised by CV and GCD analysis, respectively. EIS test revealed that ZnAl1.5O3.25 had the modest impedance value. The energy density value for ZnAl1.5O3.25 sample was 16.79 Wh/kg at 1 A/g with a power density of 179.9 W/kg. The as developed electrodes showed predominantly pseudo-capacitive charge storage mechanism.

In anaerobic conditions, sulphide oxidising bacteria (SOB) are able to spatially separate sulphide removal and electric current production. How SOB anaerobically remove sulphide, store charge and produce electric current is not yet clear. With the use of a rotating disc electrode, the redox behaviour of (poly)sulphide in absence and presence of SOB was investigated at haloalkaline conditions. Cyclic voltammetry (CV) was performed on different sulphur species in the presence or absence of SOB. Different rotation speeds and scan rates were tested.

This research explores the glycerol electrooxidation reaction (GEOR) on a platinum electrode, with a special emphasis on the role of the chemical properties of the anion present in the electrolyte composition. Essential knowledge of the mechanism and dynamics of glycerol electrooxidation is obtained through comprehensive studies that involve in situ FTIR measurements and the analysis of electrochemically oscillatory responses. This study focuses on the complex interplay between anion adsorption strength and the GEOR, focusing on the differences in CO adsorption coverage, which is the main strongly adsorbed intermediate. The anion adsorption strength, with the order HClO4 < H2SO4 < H3PO4, affects significantly not only the CO coverage on the platinum surface but also the overall glycerol electrooxidation rate. The observed differences in the electroactivity are attributed to competitive adsorption phenomena, in which specific coordinated ions have greater adsorption capabilities than perchlorate ions. These findings highlight the critical relevance of designing and optimizing electrocatalysts for glycerol electrooxidation and related processes with careful consideration of the electrolyte composition, notably the anion.

This paper investigates the effect of water content on lithium-ion battery electrolytes with particular emphasis on the degradation of lithium hexafluorophosphate, a commonly used salt in commercial electrolytes. The study addresses various degradation mechanisms caused by water in a battery system. In addition, the research utilizes electrochemical techniques to detect water and associated changes in electrochemical performance of the cell. The electrochemical water detection method investigated is very fast. The lower detection limit was not tested, but contamination of 250 ppm can be reliably detected. It can be used, for example, in experimental research to determine the purity and quality of the electrolyte used.{GRAPHIACAL ABSTRACT}

Studiens mål var att utveckla ett lågkostnadspotentiostatsystem anpasssat för batterikarakterisering och utöka dess spänningsintervall från ±2V till ±5V. Detta uppnåddes genom flera åtgärder, inklusive förändringar som utfördes både i kretsen för potentiostatens strömförsörjning och i Pythonkoden för ADC och DAC. Andra ändringar inkluderade omvandlingen av DAC:ns unipolära utspänning till bipolär spänning som appliceras på den elektrokemiska cellen, samt omvandlingen av bipolär spänning till unipolär för avläsning av data med ADC. Potentiostatens nya specifikationer validerades genom att utföra cyklisk voltammetritester på olika resistorer med samtliga strömintervall för att visa maximalt ström- och spänningsintervall grafiskt. Den nya potentiostaten hade även två nya komponenter: ett mekaniskt relä och en knappcellshållare, vilket utökade dess kapacitet och säkerhet. Slutprodukten blev en fungerande och förbättrad potentiostat som kan utföra en mängd olika elektrokemiska experiment till en betydligt lägre kostnad jämfört med kommersiella potentiostater på marknaden., The study aims to develop and design a low-cost potentiostat system for battery characterization. This was done by extending its voltage range to ±5V after it was ±2V in the former version. This was achieved by making several adjustments to the circuit of the potentiostat and its Python code. The adjustments include making changes in the power supply circuit and converting the unipolar output voltage of the DAC to the bipolar voltage that is applied to the electrochemical cell, as well as the conversion of the same bipolar voltage back to the unipolar voltage for the ADC to be able to read it and convert it to measuring data. The new specification of the potentiostat was validated by performing cyclic voltammetry tests on different resistors at all 4 different current ranges to show the maximum current and voltage range in the form of a graph. To further enhance the new potentiostat, two additional components were added to it: a mechanical relay and a coin cell holder, which are intended to increase its versatility and safety. The end product was a working and improved potentiostat that can perform a variety of electrochemical experiments at a significantly lower cost compared to commercial potentiostats on the market.

Implantable cell replacement therapies promise to completely restore the function of neural structures, possibly changing how we currently perceive the onset of neurodegenerative diseases. One of the major clinical hurdles for the routine implementation of stem cell therapies is poor cell retention and survival, demanding the need to better understand these mechanisms while providing precise and scalable approaches to monitor these cell-based therapies in both pre-clinical and clinical scenarios. This poses significant multidisciplinary challenges regarding planning, defining the methodology and requirements, prototyping and different stages of testing. Aiming toward an optogenetic neural stem cell implant controlled by a smart wireless electronic frontend, we show how an iterative development methodology coupled with a modular design philosophy can mitigate some of these challenges. In this study, we present a miniaturized, wireless-controlled, modular multisensor platform with fully interfaced electronics featuring three different modules: an impedance analyzer, a potentiostat and an optical stimulator. We show the application of the platform for electrical impedance spectroscopy-based cell monitoring, optical stimulation to induce dopamine release from optogenetically modified neurons and a potentiostat for cyclic voltammetry and amperometric detection of dopamine release. The multisensor platform is designed to be used as an opto-electric headstage for future in vivo animal experiments.

This study investigates the structure, electrochemical behavior and hydrogen evolution reaction (HER) performance of electrodeposited Ru–Co alloy coatings. The alloys were prepared from a 0.75 M Co2+ + 0.025 M Ru3+ solution at various potentials ranging from −0.5 to −1.2 V vs. SCE. Results reveal that the Ru and Co deposition processes are interdependent. The deposition of nobler Ru from the mixed metal solution reaches pure diffusion control already at −0.7 V compared to −1.0 V from a single Ru bath. On the other hand, Co deposition is significantly facilitated in the presence of Ru in the solution. Consequently, as the deposition potential changes from −0.6 to −1.0 V, Ru–Co solid solution coatings characterized by a distinct globular morphology are formed, with their Co content increasing from 22.1/7.4 to 70.2/86.1 wt% for the Cu/Ti2AlC MAX phase substrate applied. The alloy catalysts are found to show much better HER activity and stability in alkaline than in acidic solutions. The best Ru–Co@Ti2AlC sample, electrodeposited at −0.6 V, requires an overpotential of only −95 mV to deliver a current density of −100 mA cm−2 in 1 M KOH, thus outperforming most Ru–Co-based HER electrocatalysts reported to date.

Highlights Molybdenum single crystals and wires exhibit large pseudocapacitances in cyanide solution. Gold deposition takes place after partial reduction of the thin surface oxide. The partially reduced surface oxide may assist gold deposition prior to electrodeposition. Adsorbed intermediates are involved both in the deposition and dissolution of gold. The chemical adhesion of gold on molybdenum is weak and physical binding is a prerequisite.

Three boron dipyrromethane molecules (BODIPYs) were synthesized in this study with different quantities of fluorine in the meso position. The samples were characterized by NMR spectroscopy, absorption, mass spectrometry, and cyclic voltammetry, which was utilized to electrochemically measure the energy gaps between the HOMO (highest-energy occupied molecular orbital) and LUMO (lowest-energy unoccupied molecular orbital). The MTT and SRB assays were used to assess the viability of these dyes in breast cancer cells (MCF-7 and HCC-1806) and African green monkey kidney cells (Vero). The newly synthesized BODIPY tris(perfluorophenoxy)phenyl (1) compound has exhibited remarkable stability and lacks photocytotoxicity in this investigation, thus rendering it a promising candidate for application in bioimaging. At defined concentrations, the BODIPYs bearing perfluorophenyl (2) and hydroxyphenyl (3) moieties have been identified as prospective candidates for photosensitization in photodynamic therapy for breast cancer. Their notable phototoxic properties upon irradiation and the absence of significant metabolic activity reduction in normal VERO cells after 24 h of exposure suggest their potential efficacy in this therapeutic approach.

Implantable cell replacement therapies promise to completely restore the function of neural structures, possibly changing how we currently perceive the onset of neurodegenerative diseases. One of the major clinical hurdles for the routine implementation of stem cell therapies is poor cell retention and survival, demanding the need to better understand these mechanisms while providing precise and scalable approaches to monitor these cell-based therapies in both pre-clinical and clinical scenarios. This poses significant multidisciplinary challenges regarding planning, defining the methodology and requirements, prototyping and different stages of testing. Aiming toward an optogenetic neural stem cell implant controlled by a smart wireless electronic frontend, we show how an iterative development methodology coupled with a modular design philosophy can mitigate some of these challenges. In this study, we present a miniaturized, wireless-controlled, modular multisensor platform with fully interfaced electronics featuring three different modules: an impedance analyzer, a potentiostat and an optical stimulator. We show the application of the platform for electrical impedance spectroscopy-based cell monitoring, optical stimulation to induce dopamine release from optogenetically modified neurons and a potentiostat for cyclic voltammetry and amperometric detection of dopamine release. The multisensor platform is designed to be used as an opto-electric headstage for future in vivo animal experiments.

Antioxidant activity can be evaluated using cyclic voltammetry (CV). The aim of this work is to verify the efficacy of CV in evaluating the synergistic effect of bioactive compounds, such as phenolic and amino acid compounds, on antioxidant activity. Therefore, three types of model solutions were prepared: individual model solution (phenol and amino acid), (b) binary model solutions (phenol-phenol and amino acid-amino acid) and (c) mixed phenol–amino acid solutions. Electrochemical measurement conditions were optimized for phenolic compounds (pH 3.0, 1.0 g/L and 100 mV/s) and for amino acids (pH 7.0, 2.0 g/L for amino acids and 100 mV/s), and, for each solution, the functional groups responsible of the anodic and cathodic peaks were established. The peak anodic potential (Epa) and the onset potential (Eon) were two parameters of great importance. The first one was used to classify the solutions according to their antioxidant potential. In general, all the binary and mixed solutions had lower values of Epa than the corresponding individual model solution, which indicates an improvement in the antioxidant potential. The second one was used to evaluate the synergistic effects of phenolic compounds and amino acids.

Non-innocent ligands (NILs) like bis(pyridylimino)isoindolide (BPI) play crucial roles in coordination chemistry, biosciences, catalysis and material sciences. Investigating the isolated redox states of NILs is inevitable for understanding their redox-activity and fine-tuning the properties of corresponding metal complexes. The limited number of fundamental studies on the coordination behavior and redox chemistry of reduced BPI species is suggested to hamper further applications of the title compounds. This work describes for the first time the isolation of alkali metal complexes of BPI and Me2BPI in three different oxidation states and their characterization by means of NMR or EPR spectroscopy, DFT calculations, and SC-XRD studies. The latter revealed the connection between bond orders in the ligand scaffold and its oxidation state. The paramagnetic compound Me2BPI-K2 was isolated as a coordination copolymer with 18-crown-6, which enabled the characterization of the dianionic BPI radical. Furthermore, the so-far unknown trianionic state of BPI was reported by the isolation of BPI-K3. This divulges an unprecedented bis(amidinato)isoindolide coordination mode., Ministerio de Ciencia, Innovación y Universidades (España), Depto. de Química Orgánica, Fac. de Ciencias Químicas, TRUE, pub

This work focuses on the design, synthesis, characterization, and application projections of low-coordinated heavy pnictogen-containing (described by the generic letter E, hence E=C) phosphaalkenes (P=C) and arsaalkenes (As=C), with emphasis on the E=C group motifs. The work aims to understand their functional and modular character, reactivity, and potential applications by stabilizing, isolating, and characterizing these species in low-coordination environments. The thesis defines a set of elementary principles that allowed the author to better understand the materials from the perspective of "functional materials", with a subset of the compounds categorized as "smart materials" after exploring and elucidating their fascinating responses in a series of experiments using electrochemical and spectroscopic techniques. The thesis successfully explains the role of the As=C and P=C units and their innate role as "directors" of the molecular electronic structure of the compounds based on their relevant actions and interactions, which led to their naming as "group motifs". By focusing on fluorene-based and DBU-based phosphaalkene systems, the research projects extend these two families of compounds. It characterizes their responses to different functional groups, environmental conditions, and constraints as settings. The work illustrates the ability of hydrogen bonding to regulate or stabilize the reactivity of the P=C sites, showing the synthesis of hydrogen-bonded adducts that are more stabilized while maintaining the intrinsic compound identity with the P=C moieties. In addition, a fascinating copper(I)-phosphaalkene complex exhibiting photoluminescence and ambipolar properties is studied. The excited state lifetimes of the compound were measured to be in the nanosecond range, which is of interest for applications. Overall, this work represents a comprehensive study of the chemistry of heavy p-block elements and their potential as materials. This work sheds light on the

In this work, synthesized 12-tungstenphosphoric acid (H3PW12O40 × nH2O; PWA) was further ionically exchanged with Fe3+ ions, which led to the formation of the 12-tungstophosporic acid iron salt, (FePW12O40 × nH2O; Fe-PWA). Fe-PWA was then subjected to thermal analysis (TGA/DTA), determining the phase transition temperature of 576 °C from Fe-PWA to its corresponding phosphate tungsten bronze doped with iron, Fe-PWB. Using the X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), and Scanning electron microscopy with an energy dispersive X-ray spectroscopy (SEM-EDS) method, the obtained Fe-PWA and Fe-PWB were additionally characterized, and compared. Due to channels and cavities in their structures, Fe-PWA and Fe-PWB were next examined as electrode materials for aqueous rechargeable batteries. Electrochemical measurements were done in aqueous solutions of 6 M LiNO3 by cyclic voltammetry. Fe-PWA and Fe-PWB exhibit different redox processes, which are discussed thoroughly in this work. Electrochemical results are showing that within the Fe-PWA structure, more Li+ ions can be intercalated in the first discharge cycle, but consecutive cycling leads to a fast capacity fade. While the Fe-PWB redox process was stable during cycling, its specific capacity is limited by the material's poor electrical conductivity. Improvements in Fe-PWB conductivity must be addressed in future studies in order to boost material’s electrochemical performance.

Fullerene derivatives have been used as electron acceptor and transport materials in organic photovoltaics as well as in perovskite solar cells. Among them, [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) has been one of the most widely used, in combination with poly-3-hexylthiophene (P3HT) as an electron donor semiconducting polymer, for the fabrication of organic bulk heterojunction solar cells (BHJ-OSC). In this work, a steroid-fullerene hybrid was synthesized through the Bingel–Hirsch reaction to compare its properties with PC61BM as the reference structure. Different spectroscopic techniques were employed to characterize the new fullerene derivative, namely 1D and 2D nuclear magnetic resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), and high-resolution mass spectrometry (HRMS). In addition, thermogravimetric analysis (TGA), and cyclic voltammetry were also performed. The characterization was completed by transmission electron microscopy (TEM), which explore the hybrid‘s morphology, where the presence of the steroid moiety increases the solubility of the fullerene material. DFT/PBE−D3(BJ)/6-311G(d,p) calculations for both the steroid-fullerene hybrid and PC61BM allowed to obtain geometry optimizations and electronic structure data. A comparative study to analyze the nature of the electronic properties of the synthesized steroid-[60]fullerene hybrid and PC61BM with an oligomer of ten thiophene units, used in the active layer of organic solar cells, was carried out. Electron density maps using the [CIS|CNDOL/21] approach illustrate the photoexcitation of the donor followed by an electron-charge transfer to the acceptor fullerene., Ministerio de Ciencia e Innovación (España), Depto. de Química Orgánica, Fac. de Ciencias Químicas, TRUE, pub, Descuento UCM

In this study, the effect of nanoparticles of copper oxide (CuO NPs) dissolved in heat polymerizing acrylic-based soft liner was studied in artificial saliva that was used in the total denture in the mouth was identified, using the electrochemical method, to characterize the extent of the effect of nanoparticles on the oral cavity. Different concentrations (0.3% and 0.5% CuO NPs), pH, scan rates, and reproducibility were studied. The study concluded that the low percentage of 0.3% CuO NPs has less effect than the percentage of 0.5% CuO NPs by redox reaction in the artificial saliva. Furthermore, the acidic pH of the medium has less affected in oxidant that shows reduction peak appeared in the range of pH 2-6, so the nanoparticles of CuO save the acidity of the mouth, while the alkaline pH causes the oxidative effect in the artificial saliva. It can be used the nano copper to improve the chemical properties in the mouth medium.

The power of isoreticular chemistry has been widely exploited to engineer metal–organic frameworks (MOFs) with fascinating molecular sieving and storage properties but is underexplored for designing MOFs with tunable optoelectronic properties. Herein, three dipyrazole-terminated XDIs (X = PM (pyromellitic), N (naphthalene), or P (perylene); DI = diimide) with different lengths and electronic properties are prepared and employed as linkers for the construction of an isoreticular series of Zn-XDI MOFs with distinct electrochromism. The MOFs are grown on fluorine-doped tin oxide (FTO) as high-quality crystalline thin films and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Due to the constituting electronically isolated XDI linkers, each member of the isoreticular thin film series exhibits two reversible one-electron redox events, each at a distinct electrochemical potential. The orientation of the MOFs as thin films as well as their isoreticular nature results in identical cation-coupled electron hopping transport rates in all three materials, as demonstrated by comparable apparent electron diffusion coefficients, Deapp. Upon electrochemical reduction to either the [XDI]•– or [XDI]2– state, each MOF undergoes characteristic changes in its optical properties as a function of linker length and redox state of the linker. Operando spectroelectrochemistry measurements reveal that Zn-PDI@FTO (PDI = perylene diimide) thin films exhibit a record high coloration efficiency of 941 cm2 C–1 at 746 nm, which is attributed to the maximized Faradaic transformations at each electronically isolated PDI unit. The electrochromic response of the thin film is retained to more than 99% over 100 reduction–oxidation cycles, demonstrating the applicability of the presented materials.

Non-innocent ligands (NILs) like bis(pyridylimino)isoindolide (BPI) play crucial roles in coordination chemistry, biosciences, catalysis and material sciences. Investigating the isolated redox states of NILs is inevitable for understanding their redox-activity and fine-tuning the properties of corresponding metal complexes. The limited number of fundamental studies on the coordination behavior and redox chemistry of reduced BPI species is suggested to hamper further applications of the title compounds. This work describes for the first time the isolation of alkali metal complexes of BPI and Me2BPI in three different oxidation states and their characterization by means of NMR or EPR spectroscopy, DFT calculations, and SC-XRD studies. The latter revealed the connection between bond orders in the ligand scaffold and its oxidation state. The paramagnetic compound Me2BPI-K2 was isolated as a coordination copolymer with 18-crown-6, which enabled the characterization of the dianionic BPI radical. Furthermore, the so-far unknown trianionic state of BPI was reported by the isolation of BPI-K3. This divulges an unprecedented bis(amidinato)isoindolide coordination mode., MICIN, Depto. de Química Orgánica, Fac. de Ciencias Químicas, TRUE, pub

Redox species in wine are altered by pH and some wines are easily degraded due to oxidation and sulfur dioxide (SO2) reduction. There is a need for quick, easy, simple, and economical methodologies for pH and wine-oxidized products (acetaldehyde) analysis. This study aimed to measure pH and degradation of wines that were elec-trochemically analyzed using polyaniline (PANI) sensor. Gas chromatography (GC) and fourier transform infrared spectrometer (FT-IR) were also used. Electrochemical analysis showed that oxidation was accelerated and peak currents (Ip,a) and potentials (Ep,a) shifted to negative direction due to acetaldehyde formation. PANI sensor achieved a limit of detection (LOD) of 7 x 10-1 ppm and a sensitivity of 5.20 mu A ppm-1 cm-2. Acetal-dehyde formation was confirmed by GC (30%) and FT-IR spectra at 1647 cm-1 to the C--O vibration of aldehyde. These results suggested that acetaldehyde degraded the taste of wine after remaining open.