Effect of the Polar Head Type on the Surface Adsorption and Tribofilm Formation of Organic Friction Modifiers in Water-Based Lubricants.

Carboxylic acids make up a well-known group of organic friction modifiers (OFMs). OFMs can present different types of polar heads that can eventually lead to different surface adsorption properties and tribological responses. Therefore, the goal of this work is to study the effects of the polar head type on the frictional and wear performances of carboxylic acids in a water-based lubricant.

Triboelectrochemical friction control of W- and Ag-doped DLC coatings in water-glycol with ionic liquids as lubricant additives.

In the last years, diamond like carbon (DLC) coatings doped with both carbide forming and non-carbide forming metallic elements have attracted great interest as novel self-lubricating coatings. Due to the inherent properties of DLC, the doping process can provide adsorption sites for lubricant additives depending on the chemical and electrochemical state of the surface. Ionic liquids (ILs) are potential lubricant additives with good thermal stability, non-flammability, high polarity, and negligible volatility.

Effect of Steel Hardness and Composition on the Boundary Lubricating Behavior of Low-Viscosity PAO Formulated with Dodecanoic Acid and Ionic Liquid Additives.

Two ionic liquids, tributylmethylphosphonium dimethylphosphate (PP) and 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (BMP), as lubricant additives in polyalphaolefin (PAO8) were studied under boundary lubricating conditions on two types of steel (AISI 52100 bearing steel and AISI 316L stainless steel). The tribological behavior of these ILs was compared with dodecanoic acid, a well-known organic friction modifier. This study employs a ball-on-disk tribometer with an alumina ball as a counterpart.

A new azo-azomethine sensor for detection of CN and AcO- anions: Highly selective chemosensor for naked eye detection of sodium diclofenac.

New azo-azomethine sensor, HL, has been synthesized and characterized using standard spectroscopic methods. HL was found to sense CN and AcO in DMSO and semi-aqueous media over other anions such as F-, Cl-, Br-, I-, HPO- and HSO-. The anions recognition ability of HL was also evaluated using UV-Vis absorption and H NMR spectroscopy.

Chitosan hydrogels cross-linked with tris(2-(2-formylphenoxy)ethyl)amine: Swelling and drug delivery.

Tris(2-(2-formylphenoxy)ethyl)amine was designed and synthesized by reaction of salicylaldehyde with tris(2-chloroethyl)amine hydrochloride and evaluated as a new multi-functional cross-linker for preparation of new pH- and thermo-responsive chitosan hydrogels through formation of covalent Schiff-base linkage. The structure and properties of the hydrogels were characterized by FT-IR, H NMR and scanning electron microscopy (SEM). The swelling behavior of prepared hydrogels at different pHs and temperatures was investigated.

Rapid detection of HSO in water: Novel immobilized azo-azomethine colorimetric anion receptors on solid supports.

The immobilized azo-azomethine receptors on amorphous SiO, S-B, SiO nanoparticles, S-NPs, and NaY zeolite, S-ZY, have been prepared and applied as solid phase sensors for detection of HSO, over other interfering anions, in 100% aqueous media. Remarkably, S-B and S-ZY show unique and rapid sensitivity towards HSO, which could it easily visualized through naked eye detection even at 5×10molL and 4×10molL, respectively. The fabricated solid phase sensors were characterized using powder XRD diffraction, TGA-DTA, FE-SEM and also FT-IR techniques.

Selective detection of Cu and Co in aqueous media: Asymmetric chemosensors, crystal structure and spectroscopic studies.

Two new azo-azomethine receptors, HL and HL, containing hydrazine, naphthalene and different electron withdrawing groups, Cl and NO, have been designed and synthesized for qualitative and quantitative detection of Cu and Co in aqueous media. The crystal structure of HLis reported. The HLwas used as a chemosensor for selective detection of trace amount of Cu in aqueous media.

Rational design of a novel azoimine appended maleonitrile-based Salen chemosensor for rapid naked-eye detection of copper(II) ion in aqueous media.

Achieving specific selectivity and high sensitivity for the colorimetric recognition of copper(II) ions in aqueous media over a complex background of potentially competing metal ions is inherently challenging in sensor development. Thus, a novel azo-azomethine receptor (L) based on the combination of 2-amino-3-(5-bromo-2-hydroxybenzylamino)maleonitrile and azo-coupled salicylaldehyde scaffold has been designed and synthesized for the naked-eye and rapid detection of Cu(2+) ion at trace level in a wide pH range. Accordingly, the devised chemosensor distinguished Cu(2+) from other metal ions by distinct color change from light yellow to light brown without any expensive equipment.

Colorimetric detection of anions in aqueous media using N-monosubstituted diaminomaleonitrile-based azo-azomethine receptors: real-life applications.

New N-monosubstituted diaminomaleonitrile-based azo-azomethine dyes have been synthesized in order to develop colorimetric sensors for detection of biologically important anions in aqueous media. Importantly, the reported sensor decorated with strong electron-withdrawing group can detect inorganic fluoride in water even at 0.037 ppm level, which is lower than WHO permissible level (below 1 ppm).

Naked-eye detection of biologically important anions by a new chromogenic azo-azomethine sensor.

A new chromogenic azo-azomethine sensor, containing active phenolic sites, has been designed and synthesized via condensation reaction of N,N,N',N'-tetrakis(2-aminoethyl)-2,2-dimethyl propane-1,3-diamine with 1-(3-formyl-4-hydroxyphenylazo)-4-nitrobenzene. The anion recognition ability of the synthesized receptor was evaluated using UV-Vis spectroscopy and (1)H NMR technique. The anion recognition studies exhibited that the receptor acts as a sensor for biologically important anions such as F(-), AcO(-) and H2PO4(-) over other anions.

New 1,2,4-triazole-based azo-azomethine dye. Part III: Synthesis, characterization, thermal property, spectrophotometric and computational studies.

A new 1,2,4-triazole-based azo-azomethine compound, H2L, has been prepared by condensation reaction of 1-(3-formyl-4-hydroxyphenylazo)-4-ethylbenzene with prepared triazole-based diamine. The structure of H2L was characterized by using FT-IR, UV-Vis and (1)H NMR spectroscopic methods as well as elemental analysis. Hard model chemometrics method has been used to determine the formation constants of zinc(II), copper(II), nickel(II) and cobalt(II) complexes of H2L in DMSO by UV-Vis spectrophotometric method.

New acyclic 1,2,4-triazole-based Schiff base hydrazone: synthesis, characterization, spectrophotometric and computational studies.

A new 1,2,4-triazole-based Schiff base hydrazone with N, O, S donor set of atoms, H(4)L, has been prepared by condensation reaction of N,N'-bis(3-formyl-5-methylsalicylidene)ethane-1,2-diamine, H(2)L, with 4-amino-3-(4-pyridyl)-5-mercapto-1,2,4-triazole. The structure of H(4)L was characterized by using FT-IR, UV-Vis and (1)H NMR spectroscopic methods as well as elemental analysis data. The formation constants of copper(II), cadmium(II), mercury(II) and silver(I) complexes of H(4)L in DMSO were calculated using a hard model chemometrics method applying the spectrophotometric data.

New 1,2,4-triazole-based azo-azomethine dyes. Part II: synthesis, characterization, electrochemical properties and computational studies.

A new series of monoiminated 1,2,4-triazole-based azo-azomethine dyes have been synthesized via condensation reaction of 4-amino-3-methyl-5-mercapto-1,2,4-triazole with various substituted azo-coupled salicylaldehyde. The dyes have been characterized by using FT-IR, UV-Vis and (1)H NMR spectroscopic methods as well as elemental analysis. The electrochemical behavior of the dyes has been investigated by cyclic voltammetry in DMSO at five different scan rates.

Thermally stable water insoluble azo-azomethine dyes: synthesis, characterization and solvatochromic properties.

Six new water insoluble azo-azomethine dyes have been synthesized via condensation reaction of α,α'-bis(o-aminophenylthio)-1,2-xylene with substituted azo-coupled salicylaldehyde. The condensation reaction provides the expected bis-iminated azo-azomethine dyes in good yields, ranging from 59% to 90%. The dyes have been characterized by IR, UV-Vis and (1)H NMR spectroscopic methods as well as elemental analysis.

New 1,2,4-triazole-based azo-azomethine dyes. Part I: synthesis, characterization and spectroscopic studies.

Four new 1,2,4-triazole-based azo-azomethine dyes were synthesized via condensation of 3,5-diamino-1,2,4-triazole with azo-coupled o-vanillin precursors. The prepared dyes were characterized by IR, UV-vis and (1)H NMR spectroscopic methods as well as elemental analyses. Thermal properties of the prepared dyes were examined by thermogravimetric analysis.

New asymmetric heptaaza Schiff base macrocyclic complex of Mn(II): Crystal structure, biological and DFT studies.

A new asymmetric heptaaza Schiff base macrocyclic bis(pendant donor) manganese(II) complex, [MnL(1)](ClO(4))(2).CH(3)CN (1), has been prepared and characterized by X-ray diffraction and spectroscopic methods. The antimicrobial activity of 1 and a series of its familiar symmetric heptaaza [15]pydieneN(5), [16]pydieneN(5), and [17]pydieneN(5)-based bis-(2-aminoethyl) pendant armed Schiff base macrocyclic complexes of Mn(II) were tested against Escherichia coli, Staphylococcus aureus and Candida albicans.

Pyridazine-based Schiff base ligands with N4OxS2 (x=2, 4) donor set atoms: synthesis, characterization, spectral studies and 13C chemical shifts computed by the GIAO-DFT and CSGT-DFT methodologies.

Six pyridazine-based Schiff base ligands, H(2)L(n) (n=1-5) and H(4)L, with N(4)O(2)S(2) and N(4)O(4)S(2) donor set atoms, respectively, were prepared by condensation reaction of 3,6-bis-((2-aminoethyl)thio)pyridazine with various salicyladehyde derivatives in ethanol and under solvent-free polyphosphate ester catalyzed conditions. The acid-base properties of H(2)L(2) and H(2)L(3) in DMSO/water (1:1) solution have been studied by spectrophotometric method at 25 degrees C. Optimized geometries of all compounds were also obtained at the B3LYP level of theory.

Investigation of oxidation and tautomerization of a recently synthesized Schiff base in micellar media using multivariate curve resolution alternative least squares and rank annihilation factor analysis methods.

The oxidation of the recently synthesized Schiff base 3,6-bis((2-aminoethyl-5-Br-salicyliden)thio)pyridazine (PABST) with hydrogen peroxide was investigated using spectrophotometric studies. The reaction rate order and observed rate constant of the oxidation reaction was obtained in the mixture of N,N-dimethylformamide (DMF):water (30:70, v/v) at pH 10 using multivariate cure resolution alternative least squares (MCR-ALS) method and rank annihilation factor analysis (RAFA). The effective parameters on the oxidation rate constant such as percents of DMF, the effect of transition metals like Cu(2+), Zn(2+), Mn(2+) and Hg(2+) and the presence of surfactants were investigated.

Spectrophotometric determination of acidity and tautomeric constants and hydrogen bonding strength for a new Schiff base using hard modeling and multivariate curve resolution alternative least squares methods.

The equilibria of a new Schiff base derived from 3,6-bis((aminoethyl)thio)pyridazine were studied spectrophotometrically with the aid of factor-analytical methods. Hard modeling program was used for determination of the acidity constants of the Schiff base in dimethylformamide (DMF)/water mixture (30:70 v/v). In this method acidity constant equations act as hard models and the score vectors obtained by decomposing of absorbance data matrix will be linear combinations of equilibrium concentrations of species that exist in the absorption matrix.

Simultaneous determination of Co2+, Ni2+, Cu2+ and Zn2+ ions in foodstuffs and vegetables with a new Schiff base using artificial neural networks.

New complexes of Co(2+), Ni(2+), Cu(2+) and Zn(2+) with a recently synthesized Schiff base derived from 3,6-bis((aminoethyl)thio)pyridazine were applied for their simultaneous determination with artificial neural networks. The analytical data show the ratio of metal to ligand in all metal complexes is 1:1. The absorption spectra were evaluated with respect to Schiff base concentration, pH and time of the color formation reactions.

Synthesis, biological and computational study of new Schiff base hydrazones bearing 3-(4-pyridine)-5-mercapto-1,2,4-triazole moiety.

A series of new Schiff base hydrazones (compounds 1-16) were synthesized by condensation reaction of 4-amino-3-(4-pyridine)-5-mercapto-1,2,4-triazole with various aldehydes and/or dialdehydes. The structure of the prepared compounds was confirmed by means of 1H NMR, 13C NMR, UV-vis, IR and elemental analyses. The all prepared compounds were assayed for antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Candida albicans) activities by disc diffusion method.