Determined Redox Potentials Research Articles

An Electrochemical Phase Field Model Applied to Molten Salt Dealloying Corrosion of Ni-Alloys

Metal alloys in contact with molten salts are known to corrode via a dealloying process, wherein the less-noble alloy elements (e.g. Cr) are selectively oxidized and dissolved, leaving behind a corroded structure that is enriched in the more-noble elements (e.g. Ni). In some cases, this can lead to molten salt infiltration into the alloy through discrete channels along specific microstructural features (e.g. grain boundaries). However, in other cases the dealloying process promotes a more full-scale attack of the alloy, generating a fine-scale ligament structure. This process can severely degrade the alloy’s structural integrity, which limits the practicality of these material systems in otherwise promising applications (e.g. molten salt-cooled power reactors).The thermokinetic conditions for dealloying corrosion depend on the salt chemistry and the metal microstructure, which together inform the reaction process occurring at their interface. The salt chemistry and oxidant content set the electrochemical potential for selective oxidation of the less-noble elements. The associated oxidation rate is expected to depend on the presence of an interfacial structure (e.g. double layer) and also on the transport rates of reactants towards the interface (e.g. species diffusion in the metal and oxidizer transport in the salt) and reaction products away from the interface (cation transport in the salt). The corrosion rate and morphology will also depend strongly on the rate of transport laterally along the metal-salt interface, since the reorganization of the more-noble species (Ni) towards ligament formation facilitates the attack of the alloy by the corrosive agent. It has been hypothesized that molten salts enhance this rate of solute diffusion along the metal interface.In this work, we propose an electrochemical phase field model to predict the microstructural evolution of model Ni-alloys undergoing dealloying corrosion in molten fluoride salts. The model incorporates metal oxidation and dissolution via experimentally determined redox potentials and activity coefficients for metal species in the molten salt. We show that the corrosion rate and development of pores is strongly dependent on solute transport rates within the metal and also along their solid-liquid interface. In particular, we reveal a mechanism in which grain boundaries couple with the solid-liquid corrosion front to promote rapid dealloying and molten salt attack. Oxidant content in the salt and double-layer formation at the interface are discussed for their roles in setting the electrochemical potential and reaction rate at the metal-salt interface. Finally, we discuss how the model leverages insights from atomistic modeling and highlight key knowledge gaps in the mesoscale modeling of electrochemical molten salt corrosion.

Multi-Redox Systems Based on Boron Subphthalocyanines

Boron subphthalocyanines (SubPcs) are cone-shaped molecules comprised of three isoindole units bridged by aza-linkages and with a central boron atom containing an axial substituent. SubPcs are strong chromophores, but also redox-active molecules undergoing both reversible oxidation and reduction. By linking together SubPc units, multi-redox systems emerge that can take several redox states. Here I will show a variety of such scaffolds where SubPc units are either linked together at axial or peripheral positions by various acetylenic bridges. Bridges include various acyclic oligo(en)ynes and cyclic radiaannulenes containing both endo- and exocyclic carbon-carbon double bonds.1 The length and nature of the bridging unit determines whether the SubPc units are independent redox centers or whether there is communication between the units. Moreover, I will present structures were isoindole units of SubPc are replaced by thienopyrrole units2 as well as structures where the SubPc is linked to another redox-active unit, such as a triangulene.3 Experimentally determined redox potentials were compared to theoretically calculated ones, allowing us to move forward a reliable theoretical method for predicting redox properties. References a) H. Gotfredsen, L. Broløs, T. Holmstrøm, J. Sørensen, A. V. Mu ñ oz, M. D. Kilde, A. B. Skov, M. Santella, O. Hammerich, M. B. Nielsen, Org. Biomol. Chem. 2017, 15, 9809-9823; b) L. Broløs, M. D. Kilde, M. B. Nielsen, Org. Biomol. Chem. 2020, 18, 6077-6085; c) A. U. Petersen, M. G. Rasmussen, M. C. H. Thomsen, A. Ceuninck, M. B. Nielsen, Arkivoc 2020, vii, 145-157; d) H. Lissau, C. L. Andersen, F. E. Storm, M. Santella, O. Hammerich, T. Hansen, K. V. Mikkelsen, M. B. Nielsen, Chem. Commun. 2018, 54, 2763-2766. H. Gotfredsen, F. E. Storm, A. V. Muñoz, M. Santella, A. Kadziola, O. Hammerich, K. V. Mikkelsen, M. B. Nielsen, Chem. Eur. J. 2017, 23, 16194-16198. M. G. Rasmussen, M. F. Jespersen, O. Blacque, K. V. Mikkelsen, M. Juríček, M. B. Nielsen, Energy Sci. Eng. 2022, 10, 1752-1762. Figure 1

The energetics and evolution of oxidoreductases in deep time.

The core metabolic reactions of life drive electrons through a class of redox protein enzymes, the oxidoreductases. The energetics of electron flow is determined by the redox potentials of organic and inorganic cofactors as tuned by the protein environment. Understanding how protein structure affects oxidation-reduction energetics is crucial for studying metabolism, creating bioelectronic systems, and tracing the history of biological energy utilization on Earth. We constructed ProtReDox (https://protein-redox-potential.web.app), a manually curated database of experimentally determined redox potentials. With over 500 measurements, we can begin to identify how proteins modulate oxidation-reduction energetics across the tree of life. By mapping redox potentials onto networks of oxidoreductase fold evolution, we can infer the evolution of electron transfer energetics over deep time. ProtReDox is designed to include user-contributed submissions with the intention of making it a valuable resource for researchers in this field.

Redox potential of FAD-dependent glucose dehydrogenase

The redox potential is important to rationally employ oxidoreductases as bioelectrocatalysts to minimize electroactive interferences and maximize current density or cell voltage. For many FAD-dependent enzymes redox potentials are published, but not for FAD-dependent glucose dehydrogenase (GDH) from the glucose-methanol-choline (GMC)-oxidoreductase family, which are widely used in glucose biosensors. GDH is contacted via redox mediators or redox polymers and features a reasonably high substrate specificity and oxygen insensitivity. Here we report the redox potential of Glomerella cingulata GDH that was determined by two methods. Spectroelectrochemically we obtained a reduction potential of −0.265 ± 0.003 V vs SHE and with the xanthine oxidase assay using Janus green B a potential of −0.267 ± 0.016 V vs SHE. The determined redox potential of GcGDH differs greatly from that of Aspergillus niger glucose oxidase (−0.080 V vs SHE) despite an almost similar protein fold as GcGDH. Taking this excitingly low redox potential of GcGDH to develop optimized redox mediators and redox polymers for the fabrication of glucose oxidizing bioanodes with a low operating potential can drastically reduce the susceptibility of glucose biosensors towards electroactive substances or increase the cell voltage in biofuel cells.

Fine-tuning of FeS proteins monitored via pulsed EPR redox potentiometry at Q-band

As essential electron translocating proteins in photosynthetic organisms, multiple plant-type ferredoxin (Fdx) isoforms are involved in a high number of reductive metabolic processes in the chloroplast. To allow quick cellular responses under changing environmental conditions, different plant-type Fdxs in Chlamydomonas reinhardtii were suggested to have adapted their midpoint potentials to a wide range of interaction partners. We performed pulsed electron paramagnetic resonance (EPR) monitored redox potentiometry at Q-band on three Fdx isoforms for a straightforward determination of their midpoint potentials. Additionally, site-directed mutagenesis was used to tune the midpoint potential of CrFdx1 in a range of approximately −338 to −511 mV, confirming the importance of single positions in the protein environment surrounding the [2Fe2S] cluster. Our results present a new target for future studies aiming to modify the catalytic activity of CrFdx1 that plays an essential role either as electron acceptor of photosystem I or as electron donor to hydrogenases under certain conditions. Additionally, the precisely determined redox potentials in this work using pulsed EPR demonstrate an alternative method that provides additional advantages compared with the well-established continuous wave EPR technique.

Redox-dependent cytotoxicity of ferrocene derivatives and ROS-activated prodrugs based on ferrocenyliminoboronates

Four ferrocene derivatives – ferrocenecarboxylic acid, ferrocenium salt, ferroceneboronic acid, and aminoferrocene – were characterized electrochemically, and their cytotoxicity was probed using cancer cells (line MG-63). We related the observed cytotoxicity with the determined redox potentials of these four ferrocenes – aminoferrocene with its lowest redox potential exhibited the highest cytotoxicity. Thus, we synthesized four derivatives consisting of aminoferrocene and phenylboronic acid residue with the intent to employ them as ROS-activated prodrugs (ROS – reactive oxygen species). We characterized them and studied their time-dependent stability in aqueous environments. Then, we performed electrochemical measurements at oxidative conditions to confirm ROS-responsivity of the synthesized molecules. Finally, the cytotoxicity of the synthesized molecules was tested using cancer MG-63 cells and noncancerous NIH-3T3 cells. The experiments revealed sought behaviour, especially for para-regioisomers of synthesized ferrocenyliminoboronates.

In situ spectroelectrochemical investigation of a biophotoelectrode based on photoreaction centers embedded in a redox hydrogel

The field of biophotoelectrochemistry and its application in biophotovoltaics and biosensors has gained more and more attention in recent years. Knowledge of the redox potentials of the catalytically active protein cofactors in biophotovoltaic devices is crucial for accurate modelling and in discerning the mechanisms of their operation. Here, for the first time, we used spectroelectrochemical methods to investigate thermodynamic parameters of a biophotoelectrode in situ. We determined redox potentials of two elements of the system: the primary electron donor in photosynthetic reaction centers (RCs) of the bacterium Rhodobacter sphaeroides and osmium-complex based redox mediators that are bound to a hydrogel matrix. We observe that the midpoint potential of the primary donor is shifted towards more positive potentials in comparison to literature data for RCs solubilized in buffered water solution, likely due to interaction with the polymer matrix. We also demonstrate that the osmium-complex modified redox polymer efficiently wires the RCs to the electrode, maintaining a high Internal Quantum Efficiency with approximately one electron per two photons generated (IQE=50±12%). Overall, this biophotoelectrode may be attractive for controlling the redox state of the protein when performing other types of experiments, e.g. time resolved absorption or fluorescence measurements, in order to gain insights into kinetic limitations and thereby help in the rational design of bioelectronic devices.

New Reference Electrodes for Air and Moisture Stable Ionic Liquids

The use of room temperature ionic liquids (RTILs) for electrochemical applications such as fuel cells, batteries, dye-sensitized solar cells, and supercapacitors, has gained significant interest over the last decade. Despite the increase in attention, a universal reference electrode for use in RTIL electrochemistry has not been adopted. A stable, easy to prepare, and reproducible reference electrode, analogous to Ag/AgCl reference electrodes for aqueous electrochemistry, is crucial for accurately determining redox potentials as well as for comparing these potentials between RTILs and between research labs. Electrochemical work in RTILs often rely on quasi-reference electrodes (QREs),1 such as Ag or Pt wire, which must be calibrated by the addition of a redox couple (e.g. ferrocene/ferrocenium) after each electrochemical measurement. These quasi-reference electrodes are difficult to reproduce, likely due to the quality of the wire used and the presence of surface adsorbates. Furthermore, they have been known to exhibit potential drift during use, with 10s to 100s of mV drift often observed. Ferrocene is added after the experiment, however this one-point calibration of the QRE does not necessarily apply throughout the entire experiment, as the QRE may drift during the measurement.2 We report on reference electrodes designed for use in ionic liquids, which exhibit stable potential over several months of experimental use. One successful example is based on a silver wire coated with silver sulfide.3 The reference electrode potential is determined by the concentrations of Ag+ and S2 −, which are established by the solubility of the Ag2S coating on the Ag wire. Our reference electrode can be prepared and used in a normal air atmosphere, and does not need to be assembled and used in a glovebox, or protected from light. The reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five RTILs investigated over the course of 2+ months. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 17-ERD-047. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM release LLNL-ABS-748348. (1) Electrochemical aspects of ionic liquids, 2nd ed.; Ohno, H., Ed.; John Wiley & Sons Inc., 2011. (2) Torriero, A. A. J.; Sunarso, J.; Howlett, P. C. Electrochim. Acta 2012, 82, 60–68. (3) Horwood, C.; Stadermann, M. Electrochem. commun. 2018, 88, 105–108.

Quantum chemical calculations of the one-electron oxidation potential of nitroxide spin labels in biologically active compounds

Density functional theory and continuum solvent model have been used to determine standard redox potentials of oxidation of cyclic nitroxide radicals and the nitroxide derivatives of chitosan and fullerene C60 in water. Inclusion of structural relaxation of solute in water improves correlation between the measured and calculated oxidation potentials. The underlying limitations of the thermodynamic cycle model have been discussed. The computed oxidation potential of the piperidine–N–oxide derivative of chitosan is several tens mV higher than of the separate radical while the opposite trend was found for the pyrroline–N–oxide derivative of chitosan. The calculations of fullerene C60–TEMPO have shown that the 6,6–methanofullerene is more stable that the 5,6–fulleroid structure. The determined redox potential of oxidation of fullerene C60–TEMPO is significantly higher than of TEMPO in water.

Synthesis and computational study of new meta- and para-substituted ferrocenyl thioureas as potent protein kinase inhibitors and cytotoxic agents

The present study describes the synthesis, characterization, DNA binding and in vitro biological evaluation of ferrocene-enhanced thioureas. The new complexes (N1–N6) were prepared by reacting ferrocenyl anilines (A-B) with freshly prepared isothiocyanates in dry acetone. A crystallographic study of N3 revealed a supramolecular structure involving secondary non-covalent interactions (π⋯H and π⋯π). The nature and extent of the binding of these complexes with the salmon sperm DNA (SS-DNA) were examined by cyclic voltammetry and UV–Vis spectroscopy. The complexes have strong binding to DNA with binding constants ranging from 9.83 × 103 to 5.76 × 104 M−1. The shifts in the cathodic peak potentials with the addition of DNA in the electrochemical studies of the new complexes are attributed to electrostatic interactions. This observation is an indicator of the oxidizable behavior of the complexes in the presence of DNA. The theoretically calculated energies of the frontier molecular orbitals (EHOMO and ELUMO) and the Mulliken charge distributions for the optimized structures determined by the DFT/B3LYP method correlate well with the electrochemically determined redox potentials (correlation coefficient, 0.986). The computational measurements also led to a close agreement between the calculated and observed vibrational frequencies. The new complexes proved to be good candidates for protein kinase inhibition and cytotoxicity studies.

New Reference Electrodes for Air and Moisture Stable Ionic Liquids

The use of room temperature ionic liquids (RTILs) for electrochemical applications such as fuel cells, batteries, dye-sensitized solar cells, and supercapacitors, has gained significant interest over the last decade. Despite the increase in attention, a universal reference electrode for use in RTIL electrochemistry has not been adopted. A stable, easy to prepare, and reproducible reference electrode, analogous to Ag/AgCl reference electrodes for aqueous electrochemistry, is crucial for accurately determining redox potentials as well as for comparing these potentials between RTILs and between research labs. Electrochemical work in RTILs often rely on quasi-reference electrodes (QREs),1 such as Ag or Pt wire, which must be calibrated by the addition of a redox couple (e.g. ferrocene/ferrocenium) after each electrochemical measurement. These quasi-reference electrodes are difficult to reproduce, likely due to the quality of the wire used and the presence of surface adsorbates. Furthermore, they have been known to exhibit potential drift during use, with 10s to 100s of mV drift often observed. Ferrocene is added after the experiment, however this one-point calibration of the QRE does not necessarily apply throughout the entire experiment, as the QRE may drift during the measurement.2 We report on reference electrodes designed for use in ionic liquids, which exhibit stable potential over several months of experimental use. One successful example is based on a silver wire coated with silver sulfide.3 The reference electrode potential is determined by the concentrations of Ag+ and S2 −, which are established by the solubility of the Ag2S coating on the Ag wire. Our reference electrode can be prepared and used in a normal air atmosphere, and does not need to be assembled and used in a glovebox, or protected from light. The reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five RTILs investigated over the course of 2+ months. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM release LLNL-ABS-748348. (1) Electrochemical aspects of ionic liquids, 2nd ed.; Ohno, H., Ed.; John Wiley & Sons Inc., 2011. (2) Torriero, A. A. J.; Sunarso, J.; Howlett, P. C. Electrochim. Acta 2012, 82, 60–68. (3) Horwood, C.; Stadermann, M. Electrochem. Commun. 2018, 88 (December 2017), 105–108.

P-Carborane Conjugation in Radical Anions of Cage-Cage and Cage-Phenyl Compounds.

Optical electron transfer (intervalence) transitions in radical anions of p-carborane oligomers attest to delocalization of electrons between two p-carboranes cages or a p-carborane and a phenyl ring. Oligomers of the 12 vertex p-carborane (C2B10H12) cage, [12], with up to 3 cages were synthesized, as well as p-carboranes with one or two trimethylsilylphenyl groups, [6], attached to the carbon termini. Pulse radiolysis in tetrahydrofuran produced radical anions, determined redox potentials by equilibria and measured their absorption spectra. Density functional theory computations provided critical insight into the optical electron transfer bands and electron delocalization. One case, [6-12-6], showed both Robin-Day class II and III transitions. The class III transition resulted from a fully delocalized excess electron across both benzene rings and the central p-carborane, with an electronic coupling Hab = 0.46 eV between the cage and either benzene. This unprecedented finding shows that p-carborane bridges are not simply electron withdrawing insulators. In other cases with more than ∼1/2 of the excess electron localized on a [12], large cage distortions were triggered, producing a partially open cage with a nido-like structure. This resulted in class II transitions with similar Hab but massive reorganization energies. The computations also predicted delocalization in radical cations, but complexities in cation formation allowed only tentative experimental support of the predictions. The results with anions provide clear evidence for carborane conjugation that might be exploited in molecular wire materials, which are classically composed of all π-conjugated molecules.

Determining Redox Potentials of the Iron-Sulfur Clusters of the AdoMet Radical Enzyme Superfamily.

While protein film electrochemistry (PFE) has proven to be an effective tool in the interrogation of redox cofactors and assessing the electrocatalytic activity of many different enzymes, recently it has been proven to be useful for the study of the redox potentials of the cofactors of AdoMet radical enzymes (AREs). In this chapter, we review the challenges and opportunities of examining the redox cofactors of AREs in a high level of detail, particularly for the deconvolution of redox potentials of multiple cofactors. We comment on how to best assess the electroactive nature of any given ARE, and we see that when applied well, PFE allows for not only determining redox potentials, but also determining proton-coupling and ligand-binding phenomena in the ARE superfamily.

Biologically active meta-substituted ferrocenyl nitro and amino complexes: Synthesis, structural elucidation, and DFT calculations

In our search for new anticancer and DNA interacting drugs, ferrocene-incorporated nitro 1a-1b and aniline compounds 2a-2b were successfully synthesized and characterized by various physicochemical and spectroscopic methods. The proposed nitrophenylferrocenes were prepared by the coupling reaction between ferrocene and the diazonium salts of different nitroanilines using a phase transfer catalyst. In the subsequent reactions, these nitro compounds were reduced to the corresponding anilines using zinc dust/ammonium formate. Charge distribution and the HOMO/LUMO energies of the optimized structures that were calculated using the DFT/B3LYP method correlate well with the experimentally determined redox potential values. The nature and extent of binding of these complexes with the biomolecule, SS-DNA was examined by cyclic voltammetry, UV–Vis spectroscopy, and viscometry; the complexes exhibited good binding strengths to DNA. The diffusion coefficients of the compound-DNA adducts for all the complexes are lower than that of the free compound and the small values of the binding site sizes also indicate the dominance of electrostatic interactions. These compounds have also been demonstrated to be decent candidates in terms of free radical scavenging, protein kinase inhibition, and cytotoxicity.

Facile synthesis of fluoro, methoxy, and methyl substituted ferrocene-based urea complexes as potential therapeutic agents

In the present work, the synthesis, characterization (FT-IR, multinuclear (1H and 13C) NMR, AAS, Raman, and elemental analysis), DNA binding (cyclic voltammetry, UV–Vis spectroscopy and viscometry), and in vitro biological assessment of nine new ferrocene-based ureas are reported. The desulphurization of ferrocenyl thioureas to the corresponding oxo analogues using aqueous sodium hydroxide and mercuric chloride led to the ferrocenyl ureas (F1–F9) in high yields. The DNA binding studies performed by cyclic voltammetry and UV–Vis spectroscopy produced results that are in close agreement with one another for the binding constants (K) and an electrostatic mode of interaction was observed. The nature and the extent of interaction with DNA was further investigated by viscometry. The DFT/B3LYP method was used to determine the charge distribution and HOMO/LUMO energies of the optimized structure. The DFT calculated HOMO and LUMO energies correlate well with the experimentally determined redox potential values. The synthesized ferrocenyl derivatives exhibited good scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). These complexes were also scanned for their in vitro cytotoxicity against human carcinoma cell line THP-1 (leukemia cells). The results showed a moderate level of cytotoxicity against the subjected cancer cell line as compared with the standard chemotherapeutic drug (cisplatin).

A Bispidine Iron(IV)–Oxo Complex in the Entatic State

AbstractFor a series of FeIV=O complexes with tetra‐ and pentadentate bispidine ligands, the correlation of their redox potentials with reactivity, involving a variety of substrates for alkane hydroxylation (HAT), alkene epoxidation, and phosphine and thioether oxidation (OAT) are reported. The redox potentials span approximately 350 mV and the reaction rates over 8 orders of magnitude. From the experimental data and in comparison with published studies it emerges that electron transfer and the driving force are of major importance, and this is also supported by the DFT‐based computational analysis. The striking difference of reactivity of two isomeric systems with pentadentate bispidines is found to be due to a destabilization of the S=1 ground state of one of the ferryl isomers, and this is supported by the experimentally determined redox potentials and published stability constants with a series of first‐row transition metal ions with these two isomeric ligands.

A Bispidine Iron(IV)-Oxo Complex in the Entatic State.

For a series of Fe(IV) =O complexes with tetra- and pentadentate bispidine ligands, the correlation of their redox potentials with reactivity, involving a variety of substrates for alkane hydroxylation (HAT), alkene epoxidation, and phosphine and thioether oxidation (OAT) are reported. The redox potentials span approximately 350 mV and the reaction rates over 8 orders of magnitude. From the experimental data and in comparison with published studies it emerges that electron transfer and the driving force are of major importance, and this is also supported by the DFT-based computational analysis. The striking difference of reactivity of two isomeric systems with pentadentate bispidines is found to be due to a destabilization of the S=1 ground state of one of the ferryl isomers, and this is supported by the experimentally determined redox potentials and published stability constants with a series of first-row transition metal ions with these two isomeric ligands.

Study of new ferrocene-based thioureas as potential nonionic surfactants

Three new thiourea based ferrocenyl surfactants i.e. 1-(decanoyl)-3-(4-ferrocenylphenyl) thiourea (DP), 1-(decanoyl)-3-(4-ferrocenyl-2-methylbenzyl) thiourea (DMth), 1-(decanoyl)-3-(3-ferrocenylphenyl) thiourea (DM) have been successfully synthesized and well characterized by various analytical techniques, such as FT-IR, 1H and 13C NMR, AAS and elemental analysis. Furthermore, the single crystal XRD analysis was done for DP. To evaluate their amphiphilic nature, their CMC was determined through UV–visible spectroscopy that varies between 0.05 mM and 0.5 mM. The DP compound possesses lower CMC, whereas DM has considerably higher CMC value. Cyclic voltammetric technique was used to determine their redox behavior around CMC as well as their redox potentials, which follow the same trend as that of CMC. The DFT calculated energies of HOMO and LUMO orbitals correlate well with the experimentally determined redox potentials.

Bioactivity of new ferrocene incorporated N,N′-disubstituted ureas: Synthesis, structural elucidation and DFT study

We report here the synthesis, structural characterization and biological assessment of three new ferrocene incorporated ureas (1–3). The synthesis of these complexes was accomplished by the deprotection of ferrocene-based thioureas to the corresponding oxo analogues using NaOH(aq) and mercuric chloride. The new ferrocenyl ureas were characterized by FT-IR, multinuclear (1H and 13C) NMR, AAS and elemental analysis. Furthermore, the single-crystal X-ray structure of compound 2 was also determined. The DNA binding potency of these ureas was evaluated by UV–Vis spectroscopy and cyclic voltammetry (CV). The three complexes interact electrostatically with DNA and have impressive binding constants ranging from 3.42×104 to 8.15×104M−1. The diffusion coefficients of the drug–DNA adducts are lower than is that for the free drug indicating the formation of a high molecular weight complex that diffuses slowly towards the electrode. The small binding site size of 0.509 (1), 0.528 (2) and 0.473 (3) base pairs is also indicative of an electrostatic mode of interaction. The DFT calculated HOMO and LUMO energies correlate well with the experimentally determined redox potential values. The synthesized ureas (1–3) were screened for their antibacterial, antifungal and protein kinase inhibition potency. These compounds play a significant role in arresting microbial growth and are potent protein kinase inhibitors.

Design of novel additives and nonaqueous solvents for lithium-ion batteries through screening of cyclic organic molecules: an ab initio study of redox potentials.

We have screened 142 cyclic organic compounds in search of novel functional additives and nonaqueous solvents for use in lithium-ion batteries through the use of ab initio calculations, and have determined redox potentials for all molecules. We have estimated the range of variation in oxidation potentials through heteroatom replacement and structure modification. By analyzing the oxidative properties of these compounds, we have shown that substituted heteroatoms and isomers in cyclic organic molecules can induce large variations of oxidation potentials more than 2.3 V. Calculations of reduction potentials show that the substituted heteroatoms, isomers, and the number of double bonds in cyclic organic molecules can change reduction potentials more than 1.7 V. Additionally, we have identified seventeen and twelve compounds that could serve as additives in eliciting film formation on cathodes and anodes, respectively. We have also identified five compounds that could function in the overcharge protection of over-lithiated layered oxide cathodes. Finally, we have identified five compounds that could serve as electrochemically stable solvents for high-voltage (>6 V vs. Li/Li(+)) applications. These inductive screenings and their analyses and findings extend our empirical knowledge into quantitative estimation in the design of materials.