Anionic Molecules Research Articles

Homogeneous electron-transfer reaction between anionic species of anthraquinone derivatives and molecular oxygen in acetonitrile solutions: Electrochemical properties of disperse red 60

In this work, the voltammetric behaviour of disperse red 60 (DR60) in acetonitrile solutions in the presence of water and dioxygen (O2) is reported for the first time. DR60 can be reduced in two one-electron steps to form first the anion radical and then the dianion. The first reduction process of DR60 is affected by the water content of the acetonitrile, with digital simulations of the cyclic voltammetric waves supporting interactions between the radical anion and water molecules. Additionally, the presence of O2 modifies the first voltammetric process of DR60, suggesting the occurrence of homogeneous electron transfer reaction between anion radicals of DR60 and O2. Furthermore, the water content of the acetonitrile also affects the reduction wave of O2, with digital simulations supporting the occurrence of two association steps with the superoxide intermediate. The homogeneous electron transfer reaction between the quinone and oxygen species was also examined by reacting bulk electrolyzed solutions containing the anions of DR60 and O2 with neutral species of O2 and DR60, respectively, and recording the variation in the colour of the electrolyzed solutions. An equilibrium constant value was obtained from the difference between the formal reduction potentials of DR60 and O2 (−0.9955 and −0.9770, respectively, both vs. Ag in CH3CN with 0.5 M n-Bu4NPF6), indicating the direction of the homogenous electron transfer reaction (Keq = 2.013). Similarly, to confirm the occurrence of the homogeneous electron transfer reaction between O2 and another quinone based molecule, cyclic voltammetry and bulk electrolysis experiments were carried out on 9,10-anthraquinone (AQ), and its equilibrium constant value was also obtained (Keq = 4.392).

Synthesis, structural, spectral and antimicrobial activity studies of copper-nalidixic acid complex with 1,10-phenanthroline: DFT and molecular docking.

The mix-ligand coordination compound, [Cu(Nal)(Phen)(H2O)].(Phen).ClO4.(H2O)2 (Nal=Monoanion of nalidixic acid and Phen=1,10- Phenanthroline), was investigated by focusing on its supramolecular architecture. Structural properties of the complex were characterized by XRD, spectroscopic methods and elemental analysis. The complex has crystallized in the triclinic crystal system and P-1 space group. In the structure where the Cu (II) ion is in the center of symmetry, nalidixate anion and water molecule coordinated to Cu (II) metal through oxygen atoms while phen coordinated through nitrogen atoms. The monomer units are connected by hydrogen bonds to form supramolecular structures. The ground state molecular structure of the complex was optimized using DFT/B3LYP/LANL2DZ method, and compared with experimental X-ray geometry. The FT-IR study of the complex was carried out in the middle IR region focusing on the characteristic vibrations of the free ligands and the complex. Scaled calculated vibrational frequencies are compared with experimental values. The magnetic properties of the complex were investigated by electron paramagnetic resonance (EPR) spectroscopy. Further ultra-violet (UV)-visible spectral analysis was also performed to understand optical properties. The experimental UV-Vis data were associated with the calculated frontier molecular orbitals HOMO/LUMO and, molecular electrostatic potentials (MEP) are also investigated. Biological study of the complex against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Candida albicans showed very strong antibacterial activity with MIC values ranging from 128μg/ml to 1μg/ml concentration. The optimized complex is docked to the DNA Gyrase (3LPX) and gyrase tip IIA topoisomerase (3UC1).

Layered Double Hydroxide Nanosheets on Plasmonic Arrays of Al Nanocylinders for Optical Sensing

Layered double hydroxides (LDHs) are a class of materials that act as adsorbents of anionic molecules because of their positively charged layered structure. One appealing application is optical sen...

New insights into bulk and interface properties of [Bmim][Ac]/[Bmim][BF4] ionic liquid/CO2 systems — Molecular dynamics simulation approach

Ionic liquids (ILs) show great potentials for CO2 capture. In this research, we perform molecular dynamics (MD) simulations to explore bulk and interfacial behaviors of [Bmim][Ac] and [Bmim][BF4] ILs with and without CO2, in terms of transport phenomena and thermodynamics aspects. Physiochemical properties of pure ILs are calculated; structural properties such as radial distribution function (RDF) and self-diffusivity of the cations and anions are determined at various conditions. Great agreement is achieved between the experimental and calculated properties. Diffusion coefficients obtained for the cations and anions of the ILs are in the range of 3 × 10−12 to 34 × 10−12 m2/s. The cations have a higher diffusivity than the anions. It is found that the anion has an important effect on CO2 absorption, based on the coordination/structuring of CO2 around the cations and anions in the bulk systems of IL-CO2, as well as the comparison of volume expansion of the bulk system with that of pure ILs. With the addition of CO2 to ILs, the volume expansion is relatively smaller, compared to other organic solvents. The diffusion coefficient of CO2 in ILs varies from 1 × 10−10 to 3 × 10−10 m2/s, depending on temperature, CO2 concentration, and mixture viscosity. At the interface, association density between the cation and anion molecules increases. Upon CO2 diffusion, a dense interfacial layer is created that interrupts the association of the cation and anion, leading to a reduction in the interfacial tension. MD simulations also show that the diffusion of CO2 in the bulk occurs slowly. This study benefits designing appropriate ILs for various energy and environment applications under different process and thermodynamic conditions.

Regulating Droplet Dynamic Wetting Behaviors Using Surfactant Additives on High‐Temperature Surfaces

AbstractImpacting the behavior of surfactant droplets impinging upon a heated surface is an intriguing research topic, and is important in spraying cooling processes. Surfactant additives significantly increase nucleate boiling heat transfer by promoting vapor bubble nucleation and foaming. However, it is still not exactly clear how surfactants influence the droplet dynamic behaviors at the heated interfaces, nor is the relationship between the droplet dynamic behaviors and heat transfer performance. Here, three familiar surfactant molecules, i.e., anionic surfactant molecule sodium dodecyl sulfate (SDS), cationic surfactant molecule hexadecylcetyltrimethylammonium bromide (CTAB), and nonionic surfactant molecule poly(ethylene glycol) 1000 (PEG‐1000), are chosen to investigate the dynamic behaviors of the water droplets with surfactant additives on the heated smooth surface with different chemical components. At low temperatures, surfactant‐enhanced spreading of droplets on the hydrophilic and hydrophobic surfaces is achieved due to the surfactant adsorption. At high temperature, bubble jet and bubble explosion processes on the hydrophilic surfaces can generate plenty of bubbles, the bubbles flee away the heated surface and the heat transfer efficiency greatly is improved. SDS and CTAB significantly reduce the Leidenfrost point (LFP) on the hydrophilic and hydrophobic surfaces. PEG‐1000 increases the LFP, which is little affected by variation of concentration.

Kinetics of Alizarin Dye Hydrolysis in Alkaline Medium for Wastewater Treatment

The kinetics of the hydrolysis of Alizarin dye (ALZ) in basic medium is investigated for the purpose of wastewater treatment. ALZ represents a group of aromatic dyes, that are heavy, toxic, and non-biodegradable. The kinetics of the reaction was followed by UV-Vis spectrophotometry and ab-initio computational methods. The effects of initial concentration, ionic strength, and temperature were studied. The kinetic salt effect (ionic strength) demonstrated that OH– is part of the rate determining step of the reaction. Unlike common reactions, anti-Arrhenius behavior was observed within the temperature range of 25-50°C. Therefore, the apparent activation energy was determined to be -23.91 kcal/mol. Using theoretical quantum calculations, the reaction under study was investigated using the density functionals B3LYP and B97D3, and final energies were obtained using the 2nd order Moller−Plesset (MP2) theory. A complex reaction mechanism is suggested that involves the formation of an intermediate that combines the ALZ anion and water molecule attached by H-bonding. The mechanism accounted for the anti-Arrhenius behavior and the negative Ea. The standard reaction enthalpy (ΔH298) obtained using the B97D3 Grimme’s functional was within the range of the experimental Ea value.

Drug Permeability Profiling Using the Novel Permeapad® 96-Well Plate.

Here, first experiences with a prototype tool for high throughput (passive) permeability profiling, a 96-well plate comprising the Permeapad® membrane, are reported. The permeabilities of a set of drugs were determined and compared to published measures of oral absorption, such as human fraction absorbed (Fa) and in vitro permeability values obtained using other tools. The tool consists of a 96-well bottom and screen plate with the artificial, phospholipid-based barrier (Permeapad®) mounted between the plates' lower and upper compartments. The permeability of 14 model compounds including high- and low-absorption drugs, cationic, anionic, zwitterionic and neutral molecules, was determined by quantifying the compounds' transport over time, deriving the steady-state flux from the linear part of the cumulative curves and calculating the apparent permeability (Papp). The membrane structure was investigated in a high-resolution digital light microscope. The Permeapad® 96-well plate was found suited to distinguish high and low absorption drugs and yielded a hyperbolic correlation to Fa. The Papp values obtained were congruent with those determined with in-house prepared Permeapad® in the Franz cell set-up. Furthermore, good to excellent correlations were seen with Caco-2 permeability (R2= 0.70) and PAMPA permeability (R2= 0.89). Microscopic investigation of the Permeapad® barrier revealed the formation of phospholipid vesicles and myelin figures in aqueous environment. The Permeapad® 96-well plate permeation set-up is a promising new tool for rapid and reproducible passive permeability profiling.

Theoretical study of the alkali hydride anions XH–(X = Li, Na, and K)

The electronic structure of the alkali hydride anions (LiH-, NaH-, and KH-), has been investigated via ab initio CASSCF/(MRCI + Q) and R-Matrix method calculations. Comparison between the results of the two calculation methods show that the pure bound state method may be unsuitable for the calculation of the electronic states of LiH- molecule, as the potential energy curves that it presents may be spurious. The adiabatic potential energy curves and the dipole moment curves of the low-lying electronic states of alkali hydride anionic molecules are investigated in the representation 2s+1Ʌ(+/-) where the percentage ionic character fionic around the equilibrium position of the ground state X2Σ+ has been calculated. Additionally, the spectroscopic constants Te, Re, ωe, Be, the dipole moment µe, and the dissociation energy De were computed for the bound states of the two molecules NaH- and KH-. The transition dipole moment curves for the lowest 2Σ+– 2Π transition have been also presented along with their Franck-Condon factor (FCF). A rovibrational study has been performed using the canonical functions approach in order to study the nuclear motion and find the rovibrational constants for the ground and several excited states. The diagonal Franck-Condon factor f00 may provide efficient routes for the formation of cold and ultracold molecules.

Hydrogen-bonding patterns in 2,2-bis-(4-methyl-phen-yl)hexa-fluoro-propane pyridinium and ethyl-enedi-ammonium salt crystals.

The crystal structures of two salt crystals of 2,2-bis-(4-methyl-phen-yl)hexa-fluoro-propane (Bmphfp) with amines, namely, dipyridinium 4,4'-(1,1,1,3,3,3-hexa-fluoro-propane-2,2-di-yl)dibenzoate 4,4'-(1,1,1,3,3,3-hexa-fluoro-propane-2,2-di-yl)di-benzoic acid, 2C5H6N+·C17H8F6O4 2-·C17H10F6O4, (1), and a monohydrated ethyl-enedi-ammonium salt ethane-1,2-diaminium 4,4'-(1,1,1,3,3,3-hexa-fluoro-propane-2,2-di-yl)dibenzoate monohydrate, C2H10N2 2+·C17H8F6O4 2-·H2O, (2), are reported. Compounds 1 and 2 crystallize, respectively, in space group P21/c with Z' = 2 and in space group Pbca with Z' = 1. The crystals of compound 1 contain neutral and anionic Bmphfp mol-ecules, and form a one-dimensional hydrogen-bonded chain motif. The crystals of compound 2 contain anionic Bmphfp mol-ecules, which form a complex three-dimensional hydrogen-bonded network with the ethyl-enedi-amine and water mol-ecules.

Extra-Framework Content in Sodalite-Group Minerals: Complexity and New Aspects of Its Study Using Infrared and Raman Spectroscopy

Nine samples of carbonate-free sodalite-group minerals, including those with abnormally high contents of polysulfide groups, fluoride anion and carbon dioxide molecules as well as synthetic fluoraluminate sodalite-type compound Na8(Si7Al5O24)(AlF6)3–·5H2O, have been studied by means of electron microprobe analyses, infrared and Raman spectroscopy; the CO2 content was determined using the selective sorption of gaseous ignition products. This article describes a semi-quantitative method for estimating the content of carbon dioxide molecules in these minerals, based on IR spectroscopy data. The data obtained demonstrate the existence of a sulfide sodalite-group mineral with the idealized formula Na7(Si6Al6O24)(S3−)·H2O, which differs significantly from the formula Na6Ca2(Si6Al6O24)S2–2 accepted for lazurite. According to single-crystal X-ray structural analysis, in the F-rich sodalite-group mineral from the Eifel paleovolcanic region, Germany with the idealized formula Na7(Si6Al6O24)F−·nH2O fluorine occurs as an isolated F− anion, unlike synthetic F-rich sodalite-type compounds.

Hexagonal Ni(OH)2 nanosheets for stabilizing Pickering emulsion and Congo red adsorption

In this paper, hexagonal Ni(OH)2 nanosheets were prepared by hydrothermal method with nickel chloride hexahydrate as matrix and ammonia as precipitant. The lateral size of Ni(OH)2 nanosheets was about 100–250 nm. The structure of the Ni(OH)2 sheets was characterized by XRD, SEM, IR, TGA etc. Pickering emulsion was prepared by using Ni(OH)2 nanosheets as stabilizer and dichloromethane (DCM) as oil phase. Furthermore, the stability factors of Pickering emulsion and the adsorption of Congo red (CR) on interface particle layer were studied. The adsorption equilibrium of CR was analyzed by Langmuir adsorption model and Freundlich adsorption model, and the adsorption process was researched by pseudo-first-order kinetics and pseudo-second-order kinetics. Compared with Ni(OH)2 in the water phase, the Ni(OH)2 in interface particle layer exhibited a much higher adsorption capacity and a faster deposition rate. The adsorption mechanism of CR can be mainly attributed to electrostatic interaction between the positively charged interface particle layer and the anionic CR molecules. It can be expected that as a promising adsorbent for CR removal in water treatment, the Ni(OH)2 sheets in Pickering interface layer can provide a new strategy for dye adsorption.

Effect of head group of surfactant on the self-assembly structures and aggregation transitions in a mixture of cationic surfactant and anionic surfactant-like ionic liquid

Abstract The effect of head group of surfactant on the self-assembly structures and aggregation transitions, which had rarely been reported in mixed aqueous solutions of cationic surfactant and anionic surfactant-like ionic liquid molecules, was studied in three different cases. We have investigated the effect of the methyl, ethyl and 2-phenoxy-ethyl on the aggregation by the methods of turbidity, dynamic light scattering (DLS), transmission electron microscopy (TEM), rheological measurements, and steady-state fluorescence measurements. It is found that the head group has an important effect on the self-assembly structures and phase transition behaviors of mixed aqueous solutions. The ethyl group introduces a more considerable steric hindrance compared with the methyl group, which leads to the smaller packing parameter. Therefore, the system containing the methyl group has a slightly larger vesicle phase range than the system containing the ethyl group. However, compared with the ethyl group, 2-phenoxy-ethyl introduces the non-covalent pi-pi interaction between the imidazolium ring and benzene ring. This interaction easily eliminates the steric hindrance. Therefore, it is more prone to form the wormlike micelles and vesicles for the system with the 2-phenoxy-ethyl group. We also find intriguing rheological behavior from the non-spherical vesicles. Moreover, for the wormlike micelles, we find it only form in aqueous surfactant mixtures with strong interactions.

The fabrication of supramolecular assembly with quadruple switchable fluorescence by ionic self-assembly strategy

The supramolecular assembly with quadruple fluorescence switching behavior was fabricated by the complexation of cationic ferrocenyl surfactant, 16-alkyl (ferrocenyl-methyl) ammonium bromide (Fc16AB) and anionic dye molecule, Orange G (OG) via ionic self-assembly (ISA) strategy. The obtained micromaterials exhibited different morphologies (including rod-like fiber, spindle micelle and fiber bundle) and significant switchable fluorescence behavior triggered by the addition of Ce(SO4)2 and the formation of β-CD inclusion, which corresponded to “off” and “on” state of fluorescence behavior respectively. The mechanisms of fluorescence quenching and aggregation-induced emission enhancement caused by each modulation were discussed in detail. The assembly with quadruple switchable fluorescence will be meaningful in the application of multifunctional photoelectric devices.

A thin and high loading two-dimensional MOF nanosheet based mixed-matrix membrane for high permeance nanofiltration

The performance of mixed matrix membranes (MMMs) is usually limited by thick separation layer, low filler loading, and boundary defect between polymer and filler. Herein, a new two-dimensional metal-organic framework (2D MOF), named BUT-203, is designed and synthesized. Remarkably, the micron-sized crystals of this MOF could be readily delaminated into nanosheets with thickness of ca. 3 nm and lateral size of hundreds of nanometers to several microns. This delaminated nanosheets with high dispersibility in ethanol have a good compatibility with the polycation polymer polyethyleneimine (PEI). Under the optimum condition, a thin (ca. 70 nm) and high filler loading (up to ca. 73%) MMM, named BUT-203/PEI-HPAN(73) can be fabricated on macroporous hydrolyzed polyacrylonitrile (HPAN) substrate by a simple blending-spin coating method. This membrane shows a high water permeance up to 870 L/(m2·h·MPa) and high rejections (over 97.9%) for anionic dye molecules. In addition, this membrane exhibits a long term running stability, high dye desalination ability, and excellent antifouling property. These results suggest the usefulness of the membrane in nanofiltration, and simultaneously this work demonstrates that rationally designed 2D MOFs have great potential as filler materials in fabricating MMMs for various applications.

Revealing the Efficacy of Thermostable Biosurfactant in Heavy Metal Bioremediation and Surface Treatment in Vegetables.

Biosurfactants are amphiphilic molecules which showed application in the food, medical, and cosmetics industries and in bioremediation. In this study, a marine sponge-associated bacteria (MSI 54) was identified as a biosurfactant producer which showed high emulsification and surface tension-reducing property. The isolate MSI 54 was identified as Bacillus sp. and the biosurfactant was chemically characterized as a lipopeptide analog based on the spectral data including Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The MSI 54 lipopeptide biosurfactant was an anionic molecule which showed high affinity toward cationic heavy metals including Pb, Hg, Mn, and Cd. The heavy metal bioremediation efficacy of the biosurfactant was evaluated using atomic absorption spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy analysis. When MSI 54 lipopeptide biosurfactant was added to heavy metals, this resulted in a white co-precipitate of the metal–biosurfactant complex. The heavy metal remediation efficacy of the biosurfactant at a 2.0 × critical micelle concentration (CMC) showed removal of 75.5% Hg, 97.73% Pb, 89.5% Mn, and 99.93% Cd, respectively, in 1,000 ppm of the respective metal solution. The surface treatment of farm fresh cabbage, carrot, and lettuce with 2.0 × CMC of the lipopeptide showed effective removal of the surface heavy metal contaminants.

Complexation of a cationic pyrene derivative with sulfobutylether substituted β-cyclodextrin: Towards a stimulus-responsive supramolecular material

Abstract The self-aggregation of the aggregation prone molecules are avoided by employing a macrocyclic host molecule, such as β-cyclodextrin, which commonly favours the inclusion complex formation with the guest molecule and prevents the self-aggregation of the guest molecule. On the contrary, the substituted host molecules, with multiple charges are reported to promote self-aggregation of guest molecules, specifically when the guest molecules are oppositely charged. One such interesting anionic host molecule is sulfobutylether substituted β-cyclodextrin (SBE7-β-CD), which possesses both extended hydrophobic cavity as well as relatively high negative charge which makes this host capable of forming both stable inclusion complexes with the incoming guest molecule as well as inducing aggregation of guest molecules. However, there are only limited reports of this host inducing aggregation of guest molecules. In the present work, we report the interaction of SBE7-β-CD with a versatile cationic fluorescent probe, 1-pyrenemethyl amine (PMA), using ground-state absorption, steady-state emission, and time-resolved emission measurements. Interestingly, in contrast to various reports, SBE7-β-CD is found to promote the aggregation of PMA molecules. These aggregates are confirmed by the changes in the emission spectra of PMA by emergence of a distinct broad emission band at around 493 nm, which is largely red-shifted from the monomer emission peaks of PMA which appear at 375 and 395 nm. The detailed investigation of the photophysical properties of this assembly discloses that association of PMA molecules in their ground-state is induced by SBE7-β-CD instead of forming excimers in the excited state. These aggregates are found to show significant and reversible response to external stimuli such as ionic strength of medium and temperature, which makes this system to be responsive aggregate assembly to be explored in sensing applications of biochemically important analytes, which has been demonstrated by sensing Lysine and Arginine, important basic amino acids, using this PMA-SBE7-β-CD assembly.

Crystal Structure of Glycinium Dicitratoborate Monohydrate

Crystals of glycinium dicitratoborate monohydrate H3NCH2COOH[B(C6H6O7)2] · Н2О have been synthesized and selected for the first time. Their structure is determined by X-ray diffraction analysis: triclinic system, sp. gr. Р$$\bar {1}$$, and Z = 2. The crystals consist of cation–anion layers, in which all structural units (dicitratoborate anion, glycinium cation, and crystallization-water molecule) are bound firmly by numerous hydrogen bonds.

Studies on interfacial interactions between petroleum sulfonate and sulfobetaine molecules by rheological measurements

The dilational rheological properties of aqueous solutions of anionic surfactant petroleum sulfonate (KPS), zwitterionic surfactant alkyl sulfobetaine (ASB) and their mixtures have been investigated at the kerosene-water interface by the oscillating drop method. The influences of time, dilational frequency, bulk concentration and interfacial pressure on the dilational properties have been expounded. The experimental results show that the nature of film containing anionic surfactant KPS molecules is determined by the diffusion-exchange process between the bulk and the interface. On the other hand, the in-film process, such as the orientation change of hydrophilic groups, controls the properties of adsorption layers formed by betaine ASB molecules. The dilational rheological behaviors of KPS-ASB mixtures are close to those of ASB. In addition, the complex system gets the largest dilational modulus at higher bulk concentration, due to a synergistic effect between KPS and ASB caused by electrostatic attraction. The mixed adsorption of KPS and ASB may lead to more compact films and result in higher interfacial dilational modulus at optimum ratio of adsorbed KPS to ASB molecules. The mixed adsorption of KPS and ASB molecules may lead to more compact film and result in larger interfacial dilational elasticity at higher concentration.

Synthesis, spectral and structural characterization and biological activity of Cu(II) complexes with 4-(diethylamino)salicylaldehyde and α-diimines

In this article, synthesis, spectral and X-ray structure characterization, antimicrobial activity and Brine shrimp test of two new Cu(II) complexes with a salicylaldehyde derivative have been reported. Complexes [Cu(L)(bipy)]BF4·0.5H2O and [Cu2(L)2(phen)2](BF4)2 were obtained in the reaction of Cu(BF4)2·6H2O, deprotonated 4-(diethylamino)−2-hydroxybenzaldehyde ligand (L) and α-diimine (2,2’-bipyridine or 1,10-phenanthroline). The complex with bipyridine is mononuclear, containing one L and one bipyridine ligand in a distorted square-planar cation with a BF4− anion and lattice water molecule, whereas the complex with phenanthroline is a dinuclear centrosymmetric dimeric cation, containing two L ligands along with two phenanthroline ligands and BF4− anions. The coordination geometry of each Cu(II) ion can be described as an elongated square pyramid. MS-ESI spectroscopy indicated that [Cu2(L)2(phen)2](BF4)2 is mononuclear in DMSO solution. In vitro antibacterial and antifungal activity was tested against four Gram-positive, four Gram-negative bacteria and three fungal strains. Complexes showed significantly stronger antibacterial activities than parent ligands. The mononuclear phenanthroline complex in solution showed very good antimicrobial activity, which is comparable to the activity of the standard antibiotic amikacin against all tested bacterial strains. The same complex has better antifungal activity than fluconazole, which was used as a standard. Results of the brine shrimp test indicate that both complexes have good toxicity against Artemia nauplii.

Phase Separation Studies of Complexes of Intrinsically Disordered Protein Tau and Anionic Liposomes

Tau is a highly soluble intrinsically disordered protein (IDP) characterized classically as a microtubule-associated protein (MAP) in axons of mature neurons. The most well established primary function of tau is to suppress microtubule (MT) dynamic instability providing a stable foundation for organelle trafficking and cell communication. However, the dynamic and polyampholytic nature of tau's peptide composition implies a capacity to interact with charged biological substrates in the cytosol for other distinct functions. There is emerging evidence suggesting that tau associations with charged, specifically anionic, cytosolic molecules may prime pathological structural states seen in neurodegenerative diseases. However, the mechanisms of these secondary interactions are still poorly understood. Therefore, our goal is to understand the structural implications of tau associations with anionic molecules, specifically biological lipid membranes. Here we probe phase transitions of tau-anionic liposomes interactions at different anionic liposome formulations using differential interference contrast microscopy (DIC), fluorescence microscopy, and transmission electron microscopy (TEM).