Capillary electrophoretic separation of dicarboxylic acids in atmospheric aerosol particles

2,3-Pyrazinedicarboxylic acid (PZDA), 2,6-pyridinedicarboxylic acid (PDA) and 2,3-pyridinedicarboxylic acid (QUIN) solutions were studied as background electrolytes (BGEs) in the capillary electrophoretic analysis of dicarboxylic acids in aerosol particles with indirect UV detection. The BGEs were selected on the basis of similarity in structure with the analytes so that mobilities would be compatible. Optimised pH values for PZDA, PDA and QUIN solutions were 10.6, 11.0 and 10.2, respectively. Myristyltrimethylammonium hydroxide and myristyltrimethylammonium bromide were added to reverse the electroosmotic flow in the solutions in the direction of anode to enable fast anion detection. Separation was obtained for nine dicarboxylic acids (C₂–C₁₀) differing in the number of CH₂ groups in their skeleton. The electrophoretic mobilities were determined to lie in the range 3.0×10⁻⁴–7.0×10⁻⁴ cm² V⁻¹ s⁻¹. The relative standard deviations (RSDs) for the absolute migration times of the analytes were mostly less than 0.5% (n=6) in PZDA solution. In PDA solution the within-day and day-to-day RSD values for migration were less than 1% and between 2 and 4%, respectively. Peak heights and areas mostly deviated between 1 and 15% in both PZDA and PDA solutions. Detection limits ranged between 1 and 5 mg/l. Methods were applied to the analysis of dicarboxylic acids isolated from aerosol particles.     

Pharmaceutical salts of emoxypine with dicarboxylic acids

New salt forms of the antioxidant drug emoxypine (EMX, 2‐ethyl‐6‐methylpyridin‐3‐ol) with pharmaceutically acceptable maleic (Mlt), malonic (Mln) and adipic (Adp) acids were obtained {emoxypinium maleate, C₈H₁₂NO⁺·C₄H₃O₄⁻, [EMX+Mlt], emoxypinium malonate, C₈H₁₂NO⁺·C₃H₃O₄⁻, [EMX+Mln], and emoxypinium adipate, C₈H₁₂NO⁺·C₆H₉O₄⁻, [EMX+Adp]} and their crystal structures determined. The molecular packing in the three EMX salts was studied by means of solid‐state density functional theory (DFT), followed by QTAIMC (quantum theory of atoms in molecules and crystals) analysis. It was found that the major contribution to the packing energy comes from pyridine–carboxylate and hydroxy–carboxylate heterosynthons forming infinite one‐dimensional ribbons, with [EMX+Adp] additionally stabilized by hydrogen‐bonded C(9) chains of Adp⁻ ions. The melting processes of the [EMX+Mlt] (1:1), [EMX+Mln] (1:1) and [EMX+Adp] (1:1) salts were studied and the fusion enthalpy was found to increase with the increase of the calculated lattice energy. The dissolution process of the EMX salts in buffer (pH 7.4) was also studied. It was found that the formation of binary crystals of EMX with dicarboxylic acids increases the EMX solubility by more than 30 times compared to its pure form.     

New iron-cobalt clusters with silicon-containing dicarboxylic acids

For the first time, silicon-containing dicarboxylic acids were used to prepare two new heterotrinuclear carboxylates of the composition [Fe₂ ^IIICo^IIO(Bcpdps)₃(H₂O)₃], I, where H₂Bcpdps ≡ HOOC-C₆H₄-Si(C₆H₅)₂-C₆H₄COOH, and [Fe₂ ^IIICo^IIO(Ipds)₃(H₂O)₃], II, where H₂Ipds ≡ [HOOC-C₆H₃(CO)₂N-(CH₂)₃-(CH₃)₂Si]₂O. The precursor for these two complexes was trinuclear μ³-oxo-hexaacetate triaqua diiron(III)cobalt(II) cluster, {Fe ₂ CoO}, in which the acetate anions were subsequently substituted by silicon-containing dianions. The resulting products were characterized by elemental analysis, thermogravimetry, Fourier Transform Infrared (FTIR), Energy-Dispersive X-ray Fluorescence (EDXRF), and Mossbauer spectroscopies (MS). The investigation by MS revealed the presence of the iron(3+) ions in high spin state and having the close environment. Thermogravimetric analysis results indicated an improving in the thermal stability by replacing acetate anions with silicon-containing carboxyl ligands. This widens the temperature range in which such compounds can be used in practical applications.      

Binary adduct formation of desipramine with dicarboxylic acids

This paper presents the results obtained in a screening study for binary adduct formation of desipramine with three dicarboxylic acids—namely succinic, malonic and glutaric acids. Adduct formation is important because most tricyclic antidepressants show limited water solubility as free bases. Three binary adducts were prepared using a wet kneading method in non-homogenous media in presence of ethanol. Investigations of the solid state (ATR-FTIR, PXRD) and thermal analysis (TG/DTG/HF) were used for characterization of the prepared samples. The corroboration of data from employed instrumental techniques suggests that binary adducts in molar ratio 1:1 were obtained under the used experimental conditions.     

Theoretical studies on the interaction of fluorene derivatives with nucleic acids

The results of empirical and semitheoretical potential function calculations have shown that fluorene derivatives with established carcinogenic activity can intercalate, in the Lerman sense, between the complementary pairs of cytidylyl—guanosine. The interaction energy is strongly dependent on the ionization state of the compounds studied. The optimized intercalation position depends on the position of substitution on the fluorene ring and to a lesser extent on the nature of the side chain. The intercalation effect explains the different biological activity of 2- and 4-substituted isomers of acetyl-aminofluorene.     

Organotellurium derivatives of dicarboxylic acids

The freshly prepared sodium salts of ortho-phthalic acid and tetrabromo ortho-phthalic acid react with diaryltellurium dichlorides in chloroform to afford new dimeric organotellurium carboxylates, R₂Te(C₈X₄O₄)₂ (X = H, Br). The new compounds contain fourteen membered rings and the detailed structure is discussed particularly in the light of the ¹H NMR spectrum of (p-EtOC₆H₄)₂Te(C₈H₄O₄)₂ which shows inequivalence of p-ethoxy groups. The sebacate derivatives of tellurium(IV) are oligomeric and iso- and terephthalic acids failed to give well defined products.     

Synthesis of bis-fused tetrathiafulvalene with mono- and dicarboxylic acids

Bis-fused tetrathiafulvalenes with mono- and dicarboxylic acids, 2-{5-(1,3-dithiol-2-ylidene)-[1,3]dithiolo[4,5-d][1,3]dithiol-2-ylidene}-1,3-dithiole-4-carboxylic acid (1) and 2-{5-(1,3-dithiol-2-ylidene)-[1,3]dithiolo[4,5-d][1,3]dithiol-2-ylidene}-1,3-dithiole-4,5-dicarboxylic acid (2) have been synthesized. The electronic structure of 1 and 2 was examined from their optical absorption spectra and using density-functional calculations.     

Amino esters of heterocyclic dicarboxylic acids

The corresponding amino esters and their complexes with 7,7,8,8-tetracyanoquinodimethane were obtained by the condensation of the acid dichlorides of furan-2,5-dicarboxylic acid and tetrahydrothiophene-2,5-dicarboxylic acid with 8-hydroxy- and 5,7-dibromo-8-hydroxyquinolines. Almost all of the compounds obtained have antimicrobial activity.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 538–540, April, 1972.     

含B-N相互作用偶氮苯强荧光材料光电性质的理论研究

本文基于增大光谱发光强度的结构修饰方法,采用理论计算方法研究了结构修饰后分子的电子性质、光谱性质以及电荷传输性质的变化.计算结果表明,-N(CH3)2取代、-N(CH3)2和-Br组合取代有助于吸收/发射光谱发光强度的提高.与母体分子相比,-N(CH3)2和-Br取代位置不同或取代数量不同可以引起最高占据分子轨道能量(EHOMO)、最低空分子轨道能量(ELUMO)和能隙(Eg=ELUMO-EHOMO)发生明显变化,从而有效调节了最大吸收波长(λabs)和最大发射波长(λem),从理论角度设计了一系列蓝光和绿光材料.重组能计算显示,除了GM-1和GM-6,其余分子可以作为有机电致发光材料(OLEDs)中的空穴传输材料,GM-1和GM-7可以作为双极性电荷传输材料.     

Amino esters of heterocyclic dicarboxylic acids

The corresponding amino esters and their hydrochlorides and quaternary salts were obtained by the condensation of 2,5-furan- and 2,5-tetrahydrothiophenedicarboxylic acid chlorides with 1-methyl-, 1-ethyl-, or 1-butyl-3-hydroxypiperidines.deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 515–518, April, 1971.     

New nitrogen-containing derivatives of dicarboxylic acids

Conclusions New nitrogen-containing derivatives of dicarboxylic acids have been prepared and characterized: tetramethylenediphthalimide, decamethylenedisuccinimide, and tetramethylene- and decamethylene-diglutarimides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2132–2133, September, 1970.     

A novel method for determination of low molecular weight dicarboxylic acids in background atmospheric aerosol using ion chromatography

This paper describes a novel gradient elution ion chromatographic method using a Dionex AS11 system for the determination of low molecular weight dicarboxylic acids (low-M_w DCAs) in background atmospheric aerosol. Interference with the oxalic acid peak from sulfate in background PM_2.5 aerosol, 15.8 times the oxalic acid concentration, was remedied by removing sulfate using a barium cartridge, whilst interference with the malonic acid peak from carbonate was reduced by using a carbonate removal device. An alternative remedy to sulfate interference was use of an AS14 system using isocratic eluent, and this produced good resolution of oxalic acid from a high sulfate peak. In both the AS11 and the AS14 system, linear correlation coefficients were at all times >0.9990 with excellent linear range, the recoveries ranged from 92.8 to 106%, with relative standard deviation of 3.67-6.30%, whilst method detection limits (MDLs) ranged from 0.36 μg L⁻¹ for malic acid to 3.87 μg L⁻¹ for maleic acid. These data indicate that the analytical methods developed herein produce excellent separation efficiency and good determination of low-M_w DCAs with satisfactory accuracy, recoveries, and MDLs. Samples left at room temperature (20 °C) for 300 min in a simulation of the ‘waiting time’ involved in the proposed IC analysis decayed to between 86% (oxalic acid) and 39% (succinic and malonic acids) of their original concentration, whilst at 4 °C concentrations remained at 96-101% of original, indicating that maintaining samples at a low temperature prior to injection into the IC analyzer is vital for obtaining accurate results when analyzing low-M_w DCAs. Oxalic acid was found to be the most prevalent low-M_w DCA in background aerosol, comprising 57% of the total low-M_w DCAs and 0.959% of the PM_2.5 aerosol mass, followed by succinic acid and malonic acid.     

Curing behavior of epoxidized soybean oil with biobased dicarboxylic acids

In this study, we report the curing of ESO with biobased dicarboxylic acids (DCAs) with different carbon chain-lengths to synthesize fully sustainable polymers. Both non-isothermal and isothermal curing processes analysis indicated that the curing rate and activation energy decreased with increasing chain-length of DCAs. The optimum COOH/epoxy molar ratio is 0.7 for preparation of ESO/DCA cured product with maximum degree of crosslinking. Addition of 4-N, N-dimethylaminopyridine (DMAP) as a catalyst can efficiently accelerate the curing rate and reduce activation energy. We systemtically studied the effect of chain-length of DCAs on the physical properties of cured products, and found that with increase in chain-length of DCAs, the glass transition temperature of the cured ESO/DCA decreased, the tensile strength and Young's modulus increased while elongation at break decreased, due to the decreased crosslinking density resulted from the increased chain-length between crosslinking sites. All cured ESO/DCA showed excellent thermal stability with initial decomposition temperature of higher than 340 °C.     

The chemical synthesis of conductive polyaniline doped with dicarboxylic acids

The chemical polymerization of aniline was carried out in media containing different linear dicarboxylic acids with the use of oxidants such as K₂Cr₂O₇, KMnO₄, K₂S₂O₈, KIO₃ and FeCl₃. The highest yield and the conductivity were observed with K₂Cr₂O₇. The yield and the conductivity of the polyaniline (PAn) synthesized were observed to decrease in the order of oxalic acid > malonic acid > succinic acid > glutaric acid > adipic acid > phthalic acid. The solubility tests carried out in solvents such as DMF, DMSO and NMP showed that the larger the dopant molecule, the higher is the solubility of polyaniline. The PAn synthesized was characterized by measurements of conductivity, intrinsic viscosity, density and FTIR, UV-VIS and TGA techniques.     

Reaction of triethylsi lane with unsaturated mono- and dicarboxylic acids

Conclusions Two consecutive reactions, dehydrocondensation and hydrogenation, take place when triethylsilane is reacted with the cinnamic and fumaric acids in the presence of colloidal nickel.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 701–703, March, 1975.