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A novel series of Co(II), Ni(II), Cu(II) and Zn(II) mononuclear complexes have been synthesized involving a potentially tetradentate Schiff base ligand, which was obtained by condensation of 2-aminophenol with 2,5-thiophene-dicarboxaldehyde. The complexes were synthesized via reflux reaction of methanolic solution of the appropriate Schiff base ligand with one equivalent of corresponding metal acetate salt. Based on different techniques including micro analysis, FT-IR, NMR, UV-Vis, ESR, ESI-mass and conductivity measurements, four-coordinated geometry was assigned for all complexes. Spectroscopic data have shown that, the reported Schiff base coordinated to metal ions as a dibasic tetradentate ligand through the phenolic oxygen and the azomethine nitrogen. The antimicrobial activities of the parent ligand and its complexes were investigated by using the agar disk diffusion method. Antioxidation properties of the novel complexes were investigated and it was found that all the complexes have good radical scavenging properties. The binding of complexes to calf thymus DNA (CT-DNA) was investigated by absorption, emission and viscosity measurements. Binding studies have shown that all the complexes interacted with CT-DNA via intercalation mode and the binding affinity varies with relative order as Cu(II) complex > Co(II) complex > Zn(II) complex > Ni(II) complex. Furthermore, DNA cleavage properties of the metal complexes were also investigated. The results suggested the possible utilization of novel complexes for pharmaceutical applications.

An efficient and highly selective dihydrazone based fluorescent probe N ′, N ′–bis((2–hydroxynaphthalen–1–yl)methylene)malonohydrazide (H 2 nmh), has been synthesized for selective detection of Al 3+ ions and characterized by different physico–chemical and spectroscopic techniques. The probe shows an enhanced fluorescence in the presence of Al 3+ ions in ethanol–water (2:3 v/v) solution which is not observed in the presence of other cations (Na + , K + , Mg 2+ , Ca 2+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Pb 2+ , Cd 2+ and Hg 2+ ). The binding modes of H 2 nmh with Al 3+ were studied by UV–vis, fluorescence and 1 H NMR titrations. The probe act as dibasic hexa–dentate ligand and interacts with two Al 3+ ions with a binding constant K B = 5.74 × 10 9 M −1 and detection limit 5.78 × 10 −8 M. Detailed insights of probe–metal interaction mechanism were studied by mean of density functional theory (DFT) as well as time dependent–DFT calculation. MTT assay on live MCF–7 cells has been performed to evaluate the cytotoxicity of the probe which suggests viability of the probe to MCF–7 cells even at higher concentration (100 μM) with no serious cytotoxicity in cells. Live cell imaging study clearly indicates that the accumulation of Al 3+ in the cytoplasm of cells can be detected by H 2 nmh.

Specific features of complexation in solutions of a strong dibasic acid in the H2SO4–2-pyrrolidone (Pyr) system (in the range of compositions of 0–100% H2SO4) are studied using multiple frustrated total internal reflection IR spectroscopy. The conclusions drawn on the structure of the complexes formed in such solutions are confirmed by quantum-chemical calculations of the mPyr · nH2SO4 (m, n = 1, 2) heteroassociates and by comparison of their calculated and measured vibrational spectra. It is found that, in the investigated solutions, four types of acid–base complexes, with various degrees of proton transfer in the OHO bridge, are formed: (AHA)– anions with quasi-symmetric H-bonds, solvated by acid molecules, or entering into the composition of PyrH+ · (AHA)– ion pairs; quasi-ion pairs with incomplete proton transfer to the base molecule of 1: 1 and 2: 2 compositions; and 2Pyr · H2SO4 complexes with two O–H···O bridges of molecular type. The main differences in the mechanisms of the acid–base interactions in the H2SO4–Pyr system as compared to the CH3SO3H–Pyr system result from the participation of two OH-groups of H2SO4 molecule in these interactions. Therefore, two types of quasi-ion pairs and complexes of 2Pyr · H2SO4 composition are formed.

Mixtures of light and heavy water are used in NMR, small-angle neutron scattering (SANS), growth media for producing deuterated biological molecules, and analytical methods such as hydrogen–deuterium exchange (HDX) mass spectrometry. It is common to measure the pH of these solutions with a combination glass electrode with all chambers filled with aqueous (H2O) potassium chloride solutions. In the daily measurement of samples containing mixtures of H2O with D2O in some ratio – call this measurement p(H,D) – we generally do not control for all of the contributions to the differences measured in carefully controlled electrochemical experiments. For example, the calibration solutions contain relatively low concentrations of the calibrant buffer with low or no added salt. Meanwhile the tested solutions can contain widely varying levels of any number of different salts as well as both polar and nonpolar organics and polymers and proteins. In this note, the p(H,D) behaviors of 50 mM solutions of five different buffers used in biological in vitro solutions were measured over the full range of H2O : D2O ratios in the open atmosphere. After calibration, pH measurements were made with the buffer solutions alone and with 100 mM KCl added to model a significant ionic strength difference. The solutions consisted of 1 : 1 volume mixtures of the acid and base forms of acetate, monobasic/dibasic phosphate, 2-amino-2-hydroxymethyl-propane-1,3-diol (tris), 2-amino-2-hydroxymethyl-propane-1,3-diol (HEPES), and glycine to span the common, full range for biological buffers. The pH values of the 1 : 1 mixtures mean that the measurements were, in fact, of their formal pKa values. Each of the buffers exhibited a unique pattern of behavior, and none of them exhibited a measured ΔpKa = pKDa − pKHa as large as 0.4, a value that has been suggested to be added to a pH measured in H2O to match the equivalent pD measured in D2O. The results do indicate that when a reasonable, required accuracy for pH measurement is ±0.1 units, three general guidelines apply: (1) where p(H,D) values are less than 8 for any D2O content, no correction is needed for the p(H,D) measurement when comparing it to pHH; (2) for less than 50% D2O, if the 8 8, any corrections required will depend on the specific conditions and the specific buffer. Outside of the range 4 < p(H,D) < 10 or for needed greater accuracy, any corrections required will depend on the specific conditions and the identity of the buffer.

Sorption of d-metal ions (Cu2+, Fe2+, and Ni2+) from aqueous media using modified heterocyclic biopolymers takes place with the participation of sorption sites, with the following acidic groups: α-hydroxycarboxylic (monobasic, bidentate), hydroxamic (monobasic, bidentate), and aldehyde bisulphite (dibasic) in the form of chelate metal complexes, whose structures were determined through the use of computational quantum chemistry on some modeled compounds. Ion exchange mechanism of the components of hetero-phase system in electroneutral, molecular form reflects the implementation of the general laws of thermodynamics: Gibbs’ phase rule, law of mass action, law of equivalent proportions, and law of conservation of charge at electroneutrality of phases. Sorbents functional groups act as sorption sites whose filling goes in accordance with their amount, denticity, basicity and ability of metal cations to complex formation and solvation. The amount and the nature of acid sorption sites of sorbents permits the comparison of their initial and maximum sorption abilities.

Three binuclear μ-oxidobis{dioxidomolybdenum(VI)} complexes, [(μ-O){MoVIO2(MeOH)}2(L1)] 1, [(μ-O){MoVIO2(MeOH)}2(L2)] 2, and [(μ-O){MoVIO2(MeOH)}2(L3)] 3 with potential dibasic tetradentate azine ligands [H2L1 = azine of salicylaldehyde, H2L2 = azine of 3-methoxysalicyaldehyde and H2L3 = azine of 3,5-ditertiarybutylsalicylaldehyde] are reported. The complexes are characterized via elemental analysis, various spectroscopic techniques (FT-IR, UV-Vis, 1H and 13C NMR), thermogravimetric analysis and single-crystal X-ray diffraction (2 and 3) studies. These complexes are binuclear having a μ-O{MoO2}2 core where ligands coordinate through a set of phenolic oxygen and azine nitrogen to each molybdenum, thus behaving as bis(bidentate). These complexes are investigated as catalysts for the oxidation of two bicyclic alcohols (fenchyl alcohol and isoborneol) using 30% H2O2 as the oxidant in the presence of NEt3 as the additive. The conversion of bicyclic alcohols within the additives follows the order: NEt3 > py > NH3 > K2CO3 > KOH. In the presence of an N-based additive, fenchyl alcohol and isoborneol selectively give high yields of fenchone and camphor, respectively, while in the absence of the additive the conversion is relatively low.

For the first time it has been experimentally shown that a powder of detonation nanodiamonds (DND) and a saturated acyclic hydrocarbon, mono- or dibasic alcohol, used as the reaction mixture after treatment at high pressures (5–8 GPa) and high temperatures (1300–1800°C) results in the formation of diamond single crystals up to 15 micron in size. The Raman spectrum indicates that the diamonds have a perfect of crystal structure. It has been suggested that the oriented attachment mechanism is responsible for growth of micrometer-size diamond single crystals out of DND particles with sizes of about 5 nm under these technological conditions.

Jellies for oral administration are dosage forms that contain water, as stipulated in the Japanese Pharmacopeia, and heat is generally applied to the jellies during the manufacturing process. Therefore, it is difficult to formulate drugs that may be affected adversely by water and/or heat. To solve this problem, we tried to develop a powder form of gel as a novel dosage form (dry jelly: jelly medicine extemporaneously prepared) that is converted to jelly after addition of water at the time of administration. For this purpose, a basic gel formulation consisting of pectin, glucono-δ-lactone, dibasic calcium phosphate hydrate, and sucrose was investigated to evaluate the critical factors affecting gelation phenomena. The gel form was developed by adjusting the amount of each component of the formulation and of water added. Gelation occurred even with hard water containing metal ions (hardness of approximately 304 mg/L), and no changes in gel hardness occurred. The desired gel hardness could be controlled by adjusting the amount of water. The gel hardness changed over time after the addition of water, but this change did not affect the dissolution behavior of drugs formulated in the dry jelly.

pH-Responsive wormlike micelles based on microstructural transition, and formed by complexation of N-erucamidopropyl-N,N-dimethylamine (UC22AMPM) and potassium phthalic acid (PPA) at a molar ratio of 2 : 1, were developed and compared with CTAB/PPA at the same molar ratio. Phase behavior, viscoelasticity, and microstructural transitions of solutions were investigated by observing their appearance, rheological characteristics, dynamic light scattering, and 1H NMR measurements. It was found that the phase behavior of UC22AMPM/PPA solutions undergoes transitions from transparent viscoelastic fluid to phase separation with white floaters upon increasing pH. By increasing pH from 2.01 to 6.19, the viscosity of wormlike micelles in the transparent solutions continuously increased and reached ∼1.4 × 106 mPa s at pH 6.19. As pH was adjusted to 7.32, the opalescent solution showed a water-like flowing behaviour and the η0 rapidly declined to ∼1.7 mPa s. The viscosity of the CTAB/PPA solutions had a maximum at pH 2.98 and then decreased with increasing pH. This radical variation in rheological behavior is attributed to the pH dependent hydrophobicity of PPA and ultra-long hydrophobic chain of UC22AMPM. Additionally, dramatic viscosity changes of about 6 magnitudes can be triggered by varying pH without any deterioration for the UC22AMPM/PPA system.

Lipid derived diesters display excellent thermodynamic characteristics suitable for applications in phase change materials (PCMs), making them potential renewable alternatives suitable for replacing traditional petrochemical derived PCMs such as paraffins. In order to evaluate their abilities to be used as PCMs, however, it is important to understand how their structures influence the high temperature behaviour under both thermal and thermo-oxidative conditions. This study analyzed the thermal stability of three template diester systems under both inert and oxidative environments using thermogravimetric analysis (TGA) under nitrogen and air, respectively. The lipid derived diesters, synthesized from dialcohols and either oleic (unsaturated) or stearic acid (saturated), and from oleyl alcohol and various diacids, all possessed the form 18-n-18, where n represented the length of the dialcohol or diacid moiety (n = 2, 4, 6, 8, 9 or 10 carbon atoms) and 18 gave the length of the fatty acid moiety on the diol derived diesters, and the fatty alcohol moiety on the dibasic diesters. Under inert atmospheres, none of the diesters break down and are stable until they evaporate. The introduction of unsaturation raises the evaporation temperature of the reference diesters, especially at large diol chain lengths, while the reversal of the ester group lowers the evaporation temperatures with respect to the diol derived diesters. These results reveal that saturated and unsaturated diol derived diesters and saturated dibasic diesters are able to function in a wide range of applications as high as their evaporation point depending on the atmosphere present, and above ∼240 °C in all instances. Specifically, the thermal and oxidative stabilities of these diesters indicate their suitability for use in thermal energy storage as phase change materials.

A single unit sustainable drug release system was developed using hydroxypropyl methylcellulose (HPMC)-based matrices filled in capsule as the drug delivery device. Release behavior of propranolol HCl from these capsules was investigated and least square fitting was performed for the dissolution data with the different mathematical expressions. Effect of diluent, polymer, pH and hydrodynamic force on the drug release from the developed systems was investigated. The utilization of HPMC as a matrix former extended the drug release longer than 8h. HPMC viscosity grades affected the drug release, that is, increasing the amount of fillers such as lactose and dibasic calcium phosphate enhanced the drug release rate of HPMC matrices. The hydrodynamic force, type and amount of incorporated polymer apparently influenced the drug release. The physiochemical properties of polymers and interaction between HPMC and other polymers were important factors for prolongation of the drug release. The release mechanism from HPMC-based matrices in capsules was the non-Fickian transport in which the sustainable drug release of HPMC capsules could be achieved by the addition of polymeric matrix.

The incorporation of antimicrobial agents in restorative dental composites has the potential to slow the development of carious lesions.The objectives of the present study were to develop experimental composite resins with chitosan or chitosan loaded with dibasic calcium phosphate anhydrous (DCPA) particles and to demonstrate their antimicrobial potential without loss of mechanical properties or biocompatibility.Chitosan and chitosan/DCPA particles were synthetized by the electrospray method. Experimental composites were formulated by adding 0, 0.5, or 1.0 wt% particles into a resin matrix along with 60 wt% barium glass. The degree of conversion and mechanical properties were measured after 1 and 90 days of aging in water after photoactivation. Cytotoxicity and genotoxicity were evaluated using fibroblasts from dental pulp in conditioned medium. The antimicrobial activity against Streptococcus mutans was assessed by crystal violet biofilm assay.The experimental restorative composites were not found to be cytotoxic or genotoxic, with cell viability of 93.1 ± 8.0% (p = 0.328) and 3.0 ± 0.8% micronucleus per group (p = 0.1078), respectively. The antimicrobial results showed that all composites with approximately 20% less biofilm (p0.001) relative to the control. No chitosan release was detected from the composites, suggesting direct contact of the bacteria with exposed chitosan particles on the surface was responsible for the observed antimicrobial effect. The addition of the chitosan and chitosan/DCPA submicrometer (250 nm average diameter) particles to restorative composites did not change the degree of conversion, flexural strength, elastic modulus and fracture toughness compared to the control group after 90 days aging in water.It can be concluded that the addition of chitosan or chitosan/DCPA particles in the restorative composites induced antimicrobial activity without compromising the mechanical properties or biocompatibility of the composites.

Particle size is a critical parameter during tablet production as it can impact tabletability, flowability, and dissolution rate of the final product. The purpose of this study was to investigate the effect of initial particle size on fragmentation of pharmaceutical materials during tableting. Initial particle size fractions ranging from 0-125 to 355–500 µm of dibasic calcium phosphate (DCP), lactose monohydrate, and agglomerated and non-agglomerated microcrystalline cellulose (MCC) were blended with magnesium stearate and compressed into tablets. Larger initial particle sizes were found to fragment more extensively than smaller initial particle sizes for all materials based on the particle size distributions determined by laser diffraction. DCP was found to fragment most extensively followed by lactose and both MCCs. The fragmentation degrees of DCP, lactose, agglomerated and non-agglomerated MCC reached 95, 81, 32, and 29%, respectively. These findings were further supported by an increase in specific surface area with increasing compression pressure of compressed particles. The NIR spectral baseline offset from tablets was found to increase with increasing compression pressure up to 50 MPa for all materials, which was the same compression pressure range where fragmentation was observed. The NIR spectral slope from tablets as a function of compression pressure furthermore showed a similar trend as the tabletability profiles. NIR spectroscopy can thereby potentially be used as a surrogate control strategy for assessing compression related particle size changes and possibly tablet density and deformation behavior during tablet production.

A method using nisin and a chelating agent to inactivate Salmonella species and other gram-negative bacteria has been developed. The objective of this study was to determine the effect of treatment conditions on the application of this method. Ten gram-negative organisms were used in this study, including six Salmonella species commonly associated with foodborne illness. Organisms were selected on the basis of sensitivity to nisin and a chelating agent. The following parameters were examined: (a) chelating agent, (b) nisin concentration, (c) incubation temperature, and (d) protein interference. Chelating agents included EDTA, ethylenebis (oxyethylene-nitrilo) tetraacetic acid, citric acid monohydrate, and sodium phosphate dibasic. The most effective treatment consisted of 50 to 100 μg/ml nisin applied in combination with 20 mM EDTA or citric acid monohydrate at a temperature range of 30 to 42°C. All of the chelators examined exhibited some inhibitory activity. The addition of bovine serum albumin to the treatments containing nisin and EDTA did not result in a significant decrease in inhibitory action.

Inhibitors of the flaviviral serine proteases, which are crucial for the replication of dengue and West-Nile virus, have attracted much attention over the last years. A dibasic 4-guanidinobenzoate was previously reported as inhibitor of the dengue protease with potency in the low-micromolar range. In the present study, this lead structure was modified with the intent to explore structure-activity relationships and obtain compounds with increased drug-likeness. Substitutions of the guanidine moieties, the aromatic rings, and the ester with other functionalities were evaluated. All changes were accompanied by a loss of inhibition, indicating that the 4-guanidinobenzoate scaffold is an essential element of this compound class. Further experiments indicate that the target recognition of the compounds involves the reversible formation of a covalent adduct.

Vertebral compression fractures account for approximately 700,000 out of the 1.5 million total osteoporotic fractures that occur annually in the USA. There is growing interest in substituting currently utilized clinical treatments for vertebral compression fractures with an injectable, degradable, and bioactive system. In this research we studied the osteoinductive effect of calcium phosphate incorporation into cellulose nanocrystal/chitosan hydrogels with varying ratios of carbonate as an ionic crosslinker and genipin as a covalent crosslinker. As calcium and phosphate ions have been shown to be osteoinductive in time and concentration dependent manners, dibasic calcium phosphate was chosen as a bioactive additive due to its desirable controlled ion delivery potential. Gelation time, swelling ratio, erosion, compressive strength, and ion release behavior of different dibasic calcium phosphate incorporated hydrogels were evaluated. Mesenchymal stem cells were then exposed to mechanically competent hydrogels found capable of maintaining calcium and phosphate concentrations within the established bioactive range in order to assess their cytotoxicity and osteoinductivity. Our results demonstrate that hydrogels with higher covalent crosslinking possessed better mechanical properties and stabilities as well as more controlled calcium and phosphate ion release. Interestingly, dibasic calcium phosphate incorporation not only improved hydrogel bioactivity but also resulted in greater compressive strength.

We developed a simple and versatile strategy to fabricate a highly luminescent and deep-red emitting supramolecular hydrogel (λem,max = 651 nm, ΦF = 0.17). The strategy is based on using water-soluble and highly luminescent bis-pyridine molecule, V-EO7PyDCS (1), which makes a direct acid-base proton transfer and subsequent ion-pair formation with commercial poly(acrylic acid) (PAA) in water to form the luminescent supramolecular hydrogel in-situ. It was shown that the ionic interaction between the pyridinium cation in the protonated form of 1 and carboxylate anion in that of PAA was responsible for the effective gelation as to make the transparent hydrogel of ~98% water content. Concurrently, the protonated form of 1 showed a highly efficient deep-red fluorescence in this supramolecular hydrogel according to its excellent dynamic ion-pair formation and photophysical behaviors. It is noteworthy that these hydrogels are homogeneous and transparent due to the excellent water solubility of di-basic crosslinker 1.

Mineral Trioxide Aggregate (MTA) showed good clinical outcomes for many endodontic diseases. However, poor handling characteristics and anti-washout ability of MTA largely limit its widespread applications. In this study, a premixed tricalcium silicate (TCS)/sodium phosphate dibasic (SPD) cement was developed to overcome the aforementioned disadvantages of MTA. The hardening mechanism of TCS/SPD premixed pastes was studied. The influences of SPD on washout resistance, injectability, flowablity, setting time and compressive strength of the premixed TCS pastes were investigated. Considering required radiopacity, ZrO2 was incorporated, and radiopacity, anti-washout characteristics, bioactivity and sealability of radiopaque cements were studied. The results revealed that addition of SPD changed the phase compositions and morphologies of hydration products of cements. The anti-washout performance of TCS/SPD premixed cements was greatly enhanced due to improved cohesion of pastes. Additionally, TCS/SPD premixed pastes had good injectability and flowability. The setting time and compressive strength displayed a decreasing trend after adding SPD. The radiopacity of cements significantly increased from 1.54 to 3.64 mm Al with increasing ZrO2 content from 0 to 30 wt%, and the radiopaque premixed pastes showed good apatite formation-ability and sealing property. These results indicated that radiopaque TCS/SPD premixed cements could be a novel promising dental cement.

The Ritter reaction of dibasic carboxylic acids of the adamantane series with carboxy and carboxymethyl groups attached to bridgehead carbon atoms afforded a number of amino polycarboxylic acids.

A hexadentate dibasic thioether N2O2S2 donor ligand (H 2 L) and its octahedral nickel(II) complex, [Ni(L)] have been synthesized and characterized by physicochemical and spectroscopic techniques. The structures of both H 2 L and its nickel complex were confirmed by single-crystal X-ray diffraction studies. The cyclic voltammogram of the complex shows a quasi-reversible Ni(II)/Ni(III) oxidation couple (E 1/2 = 0.88 V) along with a ligand-based reduction (E 1/2 = −0.83 V). The electronic structures and electrochemical properties have been interpreted with the help of DFT calculations. The electronic transitions as calculated by TDDFT/CPCM method are used to assign the UV–Vis absorption bands.

Crystalline pure NaTi2(PO4)3 (NTP) powder was synthesized at 700°C using a simple and low energy, hybrid inorganic–organic, steric entrapment method. Sodium nitrite (NaNO2) and ammonium phosphate dibasic ((NH4)2HPO4) dissolved in water, whereas titanium (IV) isopropoxide (Ti[OCH(CH3)2]4) hydrolyzed in water. Ethylene glycol (HOCH2CH2OH) was used as a polymeric entrapper and hydrolysis of the Ti source was hindered by its dissolution in isopropyl alcohol. The resulting NTP powder was characterized by thermogravimetric analysis/differential thermal analysis, X-ray diffractometry, scanning electron microscopy, specific surface area by Brunauer–Emmett–Teller nitrogen absorption, and particle size analysis. Furthermore, C, H, N were measured by the classical Pregl-Dumas method. The thermal expansion behavior in all {hkl} pole directions was also determined by in situ high-temperature X-ray diffraction using synchrotron radiation and was found to be in agreement with other published studies.

To provide fundamental thermodynamic data for the crystallization separation of succinic acid and adipic acid from mixed dibasic acid, the solubilities of succinic acid in various mass fractions of the adipic acid + glutaric acid + acetone mixture and adipic acid in various mass fractions of the succinic acid + glutaric acid + acetone mixture were measured by the dynamic method at a temperature range of 277.85–327.95 K under atmospheric pressure. The results showed that the solubility of succinic acid in acetone increased with increasing mass fraction of adipic acid and glutaric acid in the mixed solvent at the same temperature. Similarly, the solubility of adipic acid in acetone increased with increasing mass fraction of succinic acid and glutaric acid in the mixed solvent at the same temperature. The ideal solution equation, Apelblat equation, λh equation, and nonrandom two-liquid (NRTL) equation were applied to correlate the experimental solubility data, which were all in good agreement with the four e...

A series of hydroxyl-terminated oligoesters were synthesized to determine the structural effects on the relative rates of hydrolysis in both acidic and alkaline media. Model compounds consisting of one diol and one dibasic acid were used because the simplicity of the chemical structure allowed for the analysis of individual effects. Linear, cycloaliphatic, and aromatic dibasic acids were used. The diacids were reacted with a series of linear and bulky diols. All hydroxyl-terminated oligoesters were end-capped with phenyl isocyanate. Three different stages were distinguished in the case of aliphatic oligoesters, while more bulky structures (cycloaliphatic and aromatics) only presented one or two stages. Hydrolysis rates showed a complex behavior where steric and anchimeric effects play a mutual role on initial hydrolysis rates.

Bis-protic N-heterocyclic carbene complexes of platinum and palladium (4) yield dimeric structures 6 when treated with sodium tert-butoxide in CH2Cl2. The use of a more polar solvent (THF) and a strong base (LiN(iPr)2) gave the lithium chloride adducts monobasic complex 7 or analogous dibasic complex 8.

Four novel antimicrobial phthalimido aromatic hydrazide derivatives were synthesized from N-(4-chlorocarbonylphenyl) phthalimide with benzhydrazide, salicylhydrazide, p-aminobenzohydrazide or p-aminosalicylhydrazide. They were characterized by FTIR, 1H NMR, mass spectra, elemental analyses and antimicrobial activities. These derivatives were investigated as thermal stabilizers for rigid PVC using thermogravimetric analysis technique, in nitrogen. The results revealed the greater stabilizing efficiency of the investigated derivatives as shown by their higher initial decomposition temperature and higher residual weight percent in relation to dibasic lead carbonate (DBLC), cadmium-barium-zinc (Cd–Ba–Zn) stearate and n-octyltin mercaptide (n-OTM) industrial stabilizers. The stabilizing efficiency increased with the introduction of electron donating substituent groups in the aromatic ring of the phthalimido aromatic hydrazide derivatives.

The solid–liquid phase equilibrium for the ternary succinic acid + adipic acid + ethanol system was determined at 283.15, 303.15, and 313.15 K, respectively, under about 101.3 kPa. The mutual solubility for the ternary system were obtained. At each temperature, there existed two pure solid phases in the ternary system, which were pure succinic acid and pure adipic acid, and identified by the Schreinemaker’s wet residue method and X-ray diffraction (XRD) pattern. The crystallization region of adipic acid was a little smaller than that of succinic acid at a certain temperature. The solid–liquid phase equilibrium for the ternary system was correlated and calculated by using the Wilson and NRTL models, and the corresponding binary interaction parameters were acquired. Results showed that calculated solubility values with NRTL model agreed better than those with the Wilson model. In addition, the densities of the equilibrium liquor were obtained and correlated with an empirical equation. The mutual solubility ...

Some aliphatic dibasic acid and dibasic alcohol were applied to synthesize the soft prepolyester and hard prepolyester by melting polycondensation, followed with chain extender methods to fabricate a series of biodegradable thermoplastic polyester elastomer (BTPE), which was identified by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H-NMR) and atomic force microscope (AFM). Experimental results showed that the BTPE has good mechanical properties with tensile strength up to 13 MPa while the elongation at break above 800%; the BTPE has good thermal stability with thermal decomposition temperature over 300°C and its melting point ( T m) over 100°C. Notably, the BTPE has good degradation properties, and the degree of degradation in lipase solution increases with the content of soft polyester increasing.

Two dibasic esters, the dimethyl ester of hexanedioic acid (dimethyl adipate, DBE-6) and the dimethyl ester of pentanedioic acid (dimethyl glutarate, DBE-5) were found in head-thorax extracts of male Echinothrips americanus. DBE-5 induced abdomen wagging and raising in males and females, which is typically exhibited when encountering a male. DBE-6 was avoided by males and was detected on mated, but not on virgin, females. Both substances applied to virgin females lead to females being ignored by males. The role of both substances is discussed with regard to the male mating system.

In this work, the solid–liquid phase equilibrium data for ternary system of adipic acid + glutaric acid + ethanol were measured using an isothermal saturation method at the three temperatures of 283.15, 303.15, and 313.15 K under 101.3 kPa. Three isothermal phase diagrams were built according to the measured solubility data. There were two pure solids formed in the ternary system at a given temperature, which corresponded to pure adipic acid and pure glutaric acid, and were confirmed by Schreinemaker's method of wet residue. The crystallization region of glutaric acid was smaller than that of adipic acid at each temperature. Two thermodynamic models, NRTL and Wilson were employed to correlate and calculate the mutual solubility data for the ternary adipic acid + glutaric acid + ethanol system. Results indicated that calculated results with NRTL model agreed well than those with Wilson model. Furthermore, the densities of the equilibrium liquid phase were obtained and correlated with an empirical equation.

Due to worldwide phenomenon of microbial resistance to commonly used therapeutic agents, antibiotics and antifungals, dibasic di‑/trimethylphenylcarbamic acid esters 1 – 3 , a non-traditional series of potential antimicrobials, has been in vitro evaluated against chosen Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Escherichia coli ) bacterial strains as well as against yeast ( C. albicans ) by the minimum inhibitory concentration (MIC) assay. Taking into consideration chemical structure of tested derivatives, the incorporation of more than one protonated atom of nitrogen into salt forming fragment positively influenced the activity against E. coli . On the contrary, the presence of one or more methyl groups instead of 3-alkoxy side chain attached to lipophilic aromatic moiety has not found to be favorable structural feature. In entire set of inspected compounds, the most promising results have been found for the compound 3 , chemically1-[3-piperidinium-1-yl-2-({[(2,4,6-trimethylphenyl)amino]carbonyl}oxy)propyl] piperidinium dichloride, against E. coli with the MIC=1.56 mg/mL. Key words : Dibasic phenylcarbamic acid esters, Escherichia coli , hydrogen bonding, lipophilicity

A DFT(density functional theory)/TDDFT(time-dependent density functional theory) investigation is performed to study the ground-state geometries, electronic structures, and absorption spectra of twelve ruthenium(II) thiosemicarbazone complexes [Ru(CO)(C)(Ln)], where Ln=derivatives of dibasic tetradentate Schiff-base ligand and X=AsPh3/PPh3/Py. The ground-state geometries are optimized at the B3LYP/6-31G(d)-LANL2DZ level, and the spectra are simulated by means of TD-B3LYP/6-31G(d)-LANL2DZ method on the basis of the optimized geometries. The influence of principal and secondary ligands (Ln and X) on transition characters and absorption peak positions is evaluated.

An ultrafast and facile method for the preparation of fluorescent nitrogen-doped carbon nanoparticles (CNPs) from a single precursor (ammonium citrate dibasic serving as both the carbon and nitrogen source) has been developed using a cheap home-use microwave oven. The obtained CNPs showed a strong blue fluorescence with a quantum yield of ∼20% and displayed excitation-independent fluorescence behavior. The effects of preparation conditions on the fluorescence behavior of the CNPs were systematically investigated, while the as-prepared CNPs were thoroughly characterized using various advanced techniques. The mechanism of nanoparticle formation was also discussed and proposed. Furthermore, it was found that, interestingly, explosive picric acid (PA) could quench the fluorescence signal of the CNPs significantly and selectively, while other nitroaromatic explosives have insignificant effect on their fluorescence intensity. The excellent sensing performance for picric acid could be attributed to the synergistic effect of its low molecular orbitals, the presence of fluorescence resonance energy transfer as well as acid–base interactions between the picric acid and fluorescent CNPs. These findings here suggest a simple way to prepare highly fluorescent CNPs, which holds great promise in the development of sensitive and selective sensors for PA detection.

Two oxidoperoxidotungsten(VI) complexes and the corresponding dioxidotungsten(VI) complexes of tridentate ONO donor Schiff base ligands, H2hap-nah (I) and H2hap-bhz (II) (Hhap = 2-hydroxyacetophenone, nah = nicotinoylhydrazide and bhz = benzoylhydrazide) have been reported. Complexes [WVIO(O2)(hap-nah)(MeOH)] (1), [WVIO(O2)(hap-bhz)(MeOH)] (2), [WVIO2(hap-nah)(MeOH)] (3) and [WVIO2(hap-bhz)(MeOH)] (4) have been characterized by elemental analysis, spectroscopic (IR, UV–Vis, 1H and 13C NMR) and thermogravimetric studies. Single crystal X-ray analysis of 2 and [WO(O2)(hap-inh)(MeOH)] (inh = isonicotinoylhydrazide) (whose synthesis has already been reported in the literature) confirms dibasic tridentate behavior of the ligands and their coordination to the metal ion through two oxygen and a nitrogen atoms. These complexes catalyze oxidative bromination of thymol, a model oxidative halogenation reaction normally shown by vanadium complexes, under acidic (HClO4) condition using 30% H2O2 in the presence of KBr. Under optimized reaction conditions, the selectivity of products follows the order: 4-bromothymol > 2,4-dibromothymol > 2-bromothymol.

The PVC membrane of an ion-selective electrode (ISE) sensitive to dibasic phosphate ions (HPO4-ISE) has not been optimized for maximum selectivity, sensitivity, and useable ISE lifetime and further work was necessary to improve its performance. Two areas of investigation are reported here: include the parameters for the lipophilicity of the plasticizer compound used and the amount of cyclic polyamine ionophore incorporated in the PVC membrane. Six candidate plasticizers with a range of lipophilicity were evaluated for their effect on the useable lifetime, sensitivity, and selectivity of the ISE against 13 different anions. Selectivity was determined by a modified fixed interferent method, sensitivity was determined without interferents, and the usable lifetime evaluated at the elapsed time where 50% of the HPO4-ISE failed (L50). The results show that choosing a plasticizer that has a lipophilicity similar to the ionophore’s results in the best selectivity and sensitivity and the longest L50.

Systematic determinations of electrical conductivities of sodium salts of semisynthetic penicillins, oxacillin, cloxacillin, dicloxacillin and nafcillin in the 278.15 K to 313.15 K temperature range are reported. These conductivities are examined by applying the Quint–Viallard conductivity equations and the Debye–Huckel equations for activity coefficients. Determined dissociation constants and the limiting conductances of involved anions are evaluated basing on the assumption that in dilute aqueous solutions these salts, similarly as sodium salts of natural penicillins, behave as acidic salts of dibasic acids which are the final products of degradation reactions in acidic media.

A series of copolyimides were prepared by thermal imidization of polyamide acids derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,3′,3,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, p-phenylenediamine and 4,4′-oxydialinine commonly used for the production of commercial polyimides. The flexible copolyimide films characterized by ultra-low coefficient of thermal expansion were obtained and characterized by FTIR, WAXD, TG, DMA, TMA, FE-SEM and tensile properties measurement. The results showed that three copolyimides remained semi-crystalline and exhibited high glass transition temperature, high thermal stability, and great ultimate strength.

This study evaluates the corrosion inhibitive abilities of ammonium phosphate dibasic, 8-hydroxyquinoline, calcium fluoride, sodium fluoride, sodium dodecylbenzenesulfonate and zinc nitrate with respect to the protection of the magnesium ZK30 alloy to NaCl solution. A set of characterization assays addressing morphology, composition and structural aspects of the exposed alloys were conducted, along with electrochemical evaluations. The results reveal that upon corrosion new compounds are formed onto the exposed areas of the treated alloys. The conducted experiments shed light on the corrosion mechanisms for Mg ZK30, paving the way for future developments in this area.

New chiral mononuclear cis-dioxidomolybdenum(VI) complexes, [MoO2(HL1-9)] and [MoO2(HL10)(CH3OH)], have been synthesized by the reaction of MoO2(acac)2 with tetradentate Schiff bases derived from various substituted salicylaldehydes and R(+)-3-amino-1,2-propanediol. All complexes have been characterized by elemental analysis, circular dichroism, electronic, IR and NMR (1H, 13C) spectroscopy. The molecular and crystal structure of [MoO2(HL10)(CH3OH)] elucidated by single-crystal X-ray diffraction revealed a six-coordinate distorted octahedral geometry and coordination of methanol molecule leaving one hydroxyl group uncoordinated. Surprisingly, NMR measurements made for [MoO2(HL1-9)] undoubtedly show that Schiff bases behave as dibasic tetradentate ONOO donor ligands and no solvent coordination has been observed. The catalytic activity studies have been also performed for all complexes in asymmetric sulfoxidation of thioanisole and epoxidation of styrene, cyclohexene and two monoterpenes, i.e. S(−)-limonene and (−)-α-pinene, using aqueous 30% H2O2 or tert-butyl hydroperoxide (TBHP) as the oxygen source.

A simple strategy is presented to study large sized molecular clusters taking hydrated clusters of dibasic oxalic acid, (COOH)2·nH2O, n = 9–12 as a case study. Prediction of minimum energy structures is carried out first applying Atom Centered Density Matrix Propagation (ADMP) molecular dynamic simulations. The low energy conformers thus obtained are considered as input for further optimization applying DFT based electronic structure theory with suitable DFT functional to generate more accurate structures. This approach does not allow missing any low energy structure of large sized hydrated clusters. It is observed that even in presence of twelve water molecules only one of the carboxylic protons of oxalic acid molecule is transferred to solvent water molecule. The other carboxylic proton is retained by the acid molecule.

1-[2-[({[2-/3-(Alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium/azepan- ium oxalates or dichlorides (alkoxy = butoxy to heptyloxy) were recently described as very promising antimycobacterial agents. These compounds were tested in vitro against Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212 (reference and control strains), three methicillin-resistant isolates of S. aureus, and three isolates of vancomycin-resistant E. faecalis. 1-[3-(Dipropylammonio)-2-({[3-(pentyloxy-/hexyloxy-/heptyloxy)phenyl]carbamoyl}oxy)propyl]pyrrolidinium dichlorides showed high activity against staphylococci and enterococci comparable with or higher than that of used controls (clinically used antibiotics and antiseptics). The screening of the cytotoxicity of the compounds as well as the used controls was performed using human monocytic leukemia cells. IC50 values of the most effective compounds ranged from ca. 3.5 to 6.3 &micro, M, thus, it can be stated that the antimicrobial effect is closely connected with their cytotoxicity. The antibacterial activity is based on the surface activity of the compounds that are influenced by the length of their alkoxy side chain, the size of the azacyclic system, and hydro-lipophilic properties, as proven by in vitro experiments and chemometric principal component analyses. Synergistic studies showed the increased activity of oxacillin, gentamicin, and vancomycin, which could be explained by the direct activity of the compounds against the bacterial cell wall. All these compounds demonstrate excellent antibiofilm activity, when they inhibit and disrupt the biofilm of S. aureus in concentrations close to minimum inhibitory concentrations against planktonic cells. Expected interactions of the compounds with the cytoplasmic membrane are proven by in vitro crystal violet uptake assays.

The objective of the present study is to develop floating sustained release tablet of Rebamipide for the treatment of drug induced gastric ulcer using the force of buoyancy to remain in stomach and/or Upper part of GIT for prolonged period of time for getting local action. The floating sustained release tablets of Rebamipide were prepared by direct compression method using various polymers like HPMC K100M, PEO WSR-301, sodium bicarbonate, citric acid, PVP K30, dibasic calcium phosphate and talc. Sodium bicarbonate was used as a floating effervescent agent. After preliminary screening, the floating sustained release tablets were prepared using 32 full factorial design taking HPMC K100M and PEO WSR-301 as two independent variables, and the formulation batches were evaluated for all pre-compression and post-compression parameters. The study is focused on swelling index, floating lag time, total floating Time and % CDR. From batches suggested by the design, formulation batch F8 was selected and studied extensively for release kinetic, mechanism and stability studies.

Metallogel (VLG) was obtained by reaction of tridentate dibasic donor’s ligand with vanadium pentoxide in 1:1 M ratio in H2O\DMF solution. Metallogel formation was studied using IR, UV–Visible and 1H NMR spectroscopies. Single crystal structure suitable for XRD analysis was obtained by repeated crystallization of VLG from DMF/H2O solution after few days. VLG crystallized with monoclinic P21/n space group. The ligand bonded to metal ions in tridentate dibasic fashion, together with two oxido ligand forming a square pyramidal structure. Hence, the metal ions adopted a square pyramidal geometry with slight distortion with geometrical index, τ = 0.13.

Sample preparation has become an important part of bone proteomics and paleoproteomics and remains one of the major challenges to maximizing the number of proteins characterized from bone extractions. Most paleoproteomic studies have relied on in-solution digestion with the inclusion of filter-aided sample preparation (FASP) as effective methods to detect the proteome. However, neither of these are optimal because few proteins have been detected utilizing only in-solution digestion and the molecular weight cutoff of FASP may miss remaining fragments of proteins in fossil bone. The recently developed single-pot, solid-phase-enhanced sample preparation (SP3) overcomes these issues by not relying on molecular weight while still controlling where the proteins are digested. Here, historical human bones were extracted with either 500 mM tetrasodium EDTA or 400 mM ammonium phosphate dibasic, 200 mM ammonium bicarbonate, 4 M guanidine HCl and digested with the SP3 method. Across all samples, 78 ± 7 (400-200-4) and 79 ± 17 (EDTA) protein accessions were identified, including previously difficult to detect proteins such as osteopontin. SP3 also effectively removed 90% or more of the coextracting humic substances (based on reduced absorbance) from extracted proteins. The utility of SP3 for maximizing the number of protein detections in historical bones is promising for future paleoproteomic studies.

In order to provide a more detailed view on the structure–antimycobacterial activity relationship (SAR) of phenylcarbamic acid derivatives containing two centers of protonation, 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium oxalates (1a–d)/dichlorides (1e–h) as well as 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(di-propylammonio)propyl]azepanium oxalates (1i–l)/dichlorides (1m–p, alkoxy = butoxy to heptyloxy) were physicochemically characterized by estimation of their surface tension (γ, Traube’s stalagmometric method), electronic features (log ε, UV/Vis spectrophotometry) and lipophilic properties (log kw, isocratic RP-HPLC) as well. The experimental log kw dataset was studied together with computational logarithms of partition coefficients (log P) generated by various methods based mainly on atomic or combined atomic and fragmental principles. Similarities and differences between the experimental and in silico lipophilicity descriptors were analyzed by unscaled principal component analysis (PCA). The in vitro activity of compounds 1a–p was inspected against Mycobacterium tuberculosis CNCTC My 331/88 (identical with H37Rv and ATCC 2794, respectively), M. tuberculosis H37Ra ATCC 25177, M. kansasii CNCTC My 235/80 (identical with ATCC 12478), the M. kansasii 6509/96 clinical isolate, M. kansasii DSM 44162, M. avium CNCTC My 330/80 (identical with ATCC 25291), M. smegmatis ATCC 700084 and M. marinum CAMP 5644, respectively. In vitro susceptibility of the mycobacteria to reference drugs isoniazid, ethambutol, ofloxacin or ciprofloxacin was tested as well. A very unique aspect of the research was that many compounds from the set 1a–p were highly efficient almost against all tested mycobacteria. The most promising derivatives showed MIC values varied from 1.9 μM to 8 μM, which were lower compared to those of used standards, especially if concerning ability to fight M. tuberculosis H37Ra ATCC 25177, M. kansasii DSM 44162 or M. avium CNCTC My 330/80. Current in vitro biological assays and systematic SAR studies based on PCA approach as well as fitting procedures, which were supported by relevant statistical descriptors, proved that the compounds 1a–p represented a very promising molecular framework for development of ‘non-traditional’ but effective antimycobacterial agents.

The dissociation and complexation ability toward Cu(II) of acidic type phosphoryl-containing podands – tetrabasic 1,5-bis[2-(dioxyphosphoryl)-4-ethylphenoxy]-3-oxapentane (L1), dibasic – 1,5-bis[2-(ethoxyhydroxyphosphoryl)-4-ethylphenoxy]-pentane (L2) and also of their carboxylic analogue dibasic 1,5-bis[2-(oxycarbonylphenoxy)]-3-oxapentane (L3) were investigated by spectrophotometric, conductometric and potentiometric methods in water in the presence 5% of dimethyl formamide. Spectrophotometric and conductometric titration data provided evidence for formation of 1:1 (M:L) complexes. The dissociation constants were determined and species distribution diagrams for studied acids were obtained by potentiometric method. These data are of interest for the design of binary extragents and medicinal drugs based on the studied ligands. The stability constants of Cu(II) 1:1 (M:L) complexes were estimated. Analysis of the titration curves suggests that deprotonation forms of the studied ligands react with Cu2+. Substitution of carboxylic groups in acyclic polyesters by phosphonic results in increased stability of the copper(II) complexes, Спектрофотометрическим, кондуктометрическим и потенциометрическим методами в воде в присутствии 5% диметилформамида изучена диссоциация и комплексообразование с катионом Сu(II) фосфорилподандов кислотного типа: четырёхосновного – 1,5-бис[2-(диоксифосфорил)-4-этилфенокси]-3-оксапентана (L1), двухосновного – 1,5-бис[2-(оксиэтоксифосфорил)-4-этилфенокси]-пентана (L2), а также их карбонильного аналога – полиэфирной дикарбоновой кислоты 1,5-бис[2-(оксикарбонилфенокси)]-3-оксапентана (L3). Данные спектрофотометрических и кондуктометрических титрований свидетельствуют об образовании комплексов состава 1 : 1 (M : L). Методом потенциометрического титрования определены значения констант диссоциации и получены диаграммы распределения форм ионизации изученных соединений в зависимости от рН среды, которые представляют несомненный интерес при создании бинарных экстрагентов и медицинских препаратов на основе этих соединений. Определены значения констант устойчивости комплексов с катионом Cu2+ состава 1 : 1 (M : L). Анализ кривых титрования позволяет сделать вывод о том, что в реакцию с Cu2+ вступают депротонированные формы исследуемых лигандов. Замена карбоксильных групп в молекулах ациклических полиэфиров на фосфоновые приводит к заметному увеличению устойчивости образующихся комплексов меди(II) с близкими по строению лигандами L3 и L1.

In our ongoing efforts to develop novel trace metal complexes with therapeutically interesting properties, a neutral mono nuclear oxidomethoxidovanadium(V) complex, [VVO(OCH3)(hpdbal-sbdt)] (1) and a μ-O bridged dinuclear oxidovanadium(V) complex, [{VVO(hpdbal-sbdt)}2μ−O] (2) [H2hpdbal-sbdt (I) is a tridentate and dibasic ONS2― donor ligand obtained through the Schiff base reaction of 2-hydroxy-5-(phenyldiazenyl)benzaldehyde (Hhpdbal) and S-benzyldithiocarbazate (Hsbdt)] have been synthesized and characterized by various analytical techniques such as TGA, EDS, ATR-IR, UV–Vis, CV, 1H NMR, 13C NMR and 51V NMR. Single-crystal X-ray diffraction analysis of 1 confirms the coordination of phenolate oxygen, imine nitrogen and thioenolate sulfur of the ligand to the vanadium center with a distorted tetragonal-pyramidal geometry. The compound 2 triggered apoptotic and reproductive death of the cancer cells in vitro with 76% and 62% growth inhibition of human breast adenocarcinoma (MCF-7) and human lung carcinoma cells (A549) respectively. The compound 2 was found to be sufficiently stable over a wide window of physiological pH. The complex 2 was studied further for its interaction with a drug carrier protein BSA with the aid of spectroscopic techniques viz. fluorescence, temperature controlled UV–vis and deconvoluted IR techniques.