O-phthalic Acid Research Articles

Engineering bacterial biocatalysts for the degradation of phthalic acid esters.

Phthalic acid esters (PAEs) are synthetic diesters derived from o-phthalic acid, commonly used as plasticizers. These compounds pose significant environmental and health risks due to their ability to leach into the environment and act as endocrine disruptors, carcinogens, and mutagens. Consequently, PAEs are now considered major emerging contaminants and priority pollutants. Microbial degradation, primarily by bacteria and fungi, offers a promising method for PAEs bioremediation. This article highlights the current state of microbial PAEs degradation, focusing on the major bottlenecks and associated challenges. These include the identification of novel and more efficient PAE hydrolases to address the complexity of PAE mixtures in the environment, understanding PAEs uptake mechanisms, characterizing novel o-phthalate degradation pathways, and studying the regulatory network that controls the expression of PAE degradation genes. Future research directions include mitigating the impact of PAEs on health and ecosystems, developing biosensors for monitoring and measuring bioavailable PAEs concentrations, and valorizing these residues into other products of industrial interest, among others.

Chemically Reversible Translational Moiré Superlattice Formations in the Two-Dimensional Films of the Zinc Phthalate Complex.

The exciting electronic properties of two-dimensional layered materials introduced by twist angle and lattice mismatch between two consecutive layers are well-recognized. The major challenge lies in the control over the moiré periodicity. Herein, we report a chemically directed way to achieve the desired precision over moiré periodicity of the assembly of a complex of zinc ions and o-phthalic acid utilizing soft bonds. The reaction of o-phthalic acid with zinc ions in the aqueous medium at 80 °C for 1 h followed by preserving the reaction mixture at ambient temperature (35 °C) resulted in translational moiré superlattices with precise periods. Those lattices are further stacked angularly to give rotational super-moiré lattices. Further, the role of the π-zinc ion interaction in the origin of moiré fringes was examined with the reaction with 8-hydroxyquinoline-5-sulfonic acid (HQS) that also established the reversible nature of the superlattices. The present observations also suggest the formation of moiré superlattice through ion insertion in a chemical lattice.

Computational study of the solvation effect of supercritical water on o-phthalic acid decarboxylation by varying the solvent dielectric constant

This study investigates the solvation effect on the decarboxylation of o-phthalic acid using quantum calculations with a continuum solvation model with varying dielectric constants. Two mechanisms were considered: with and without a catalytic water molecule. The latter had a lower reaction barrier. Increasing the dielectric constant facilitates the hydrogen transfer but impedes C–C bond breaking in both mechanisms. The change in the free energies due to solvation of the transition state is generally greater than the reactant. The reaction barrier predominantly increased with the dielectric constant in both mechanisms. The Kirkwood slope estimated by plotting estimated rate constants against the Kirkwood polarity parameter, (ε−1)/(2ε+1), was close to the experimental value (only for the assisted mechanism). The simulations indicate that the solvation effect on the decarboxylation rate can be elucidated by considering the effect of dielectric constant of supercritical water.

Case Study of Diesters of o-Phthalic Acid in Surface Waters with Background Levels of Pollution.

Lake Baikal was studied as a model for elucidating the general pattern of o-phthalic acid diester (PAE) distributions in surface waters with background pollution levels. The influence of factors including congeners, concentrations, sampling points, seasons, years, and potential sources was considered and the environmental risk for various hydrobionts was established. Priority PAEs in Baikal waters are represented by dimethyl phthalate (DMP), diethyl phthalates (DEP), di-n-butyl phthalate (DnBP) and di-(2-ethylhexyl)phthalate (DEHP). Statistically valuable average concentrations and ranges for DMP, DEP, DnBP, and DEHP were 0.02 (0.01-0.02), 0.07 (0.06-0.09), 0.55 (0.47-0.66), and 0.30 (0.26-0.34) µg/L, respectively. The main factors determining PAE concentrations were the year and season of sampling, whereas sampling points were not among the factors influencing PAE levels. The distribution of PAEs in the water body was characterized by (i) an even distribution of minor hydrophilic DMP and DEP congeners in the whole water body, (ii) a maximum concentration of hydrophobic DnBP and DEHP congeners in the upper and near-bottom layers of the water column, and (iii) a low concentration of hydrophobic congeners in the near-shore area. The main PAE source was found to be the atmospheric transfer of polluted air masses, while the supply of PAEs from coastal sources to the pelagic zone was low. The contribution of biogenic sources to the background level of PAEs in the surface waters of Lake Baikal was established. The ecological risk of the background concentration level of PAEs for Lake Baikal biota was estimated. It was found that (i) DMP and DEP congeners do not represent a risk, or represent a very low risk, (ii) the concentration levels of dominant DnBP and DEHP congeners represent a low risk for crustaceans and fishes but (iii) a rather high risk for algae at a DEHP concentration of 0.30 µg/L.

Diversity and Allelopathic Potential of Weeds in Swampland

Weeds are plant disturbing organism that affect yields through competition and allelopathy. However, not much is known about weed diversity in swamps, so research is needed to identify their types and compounds as a weed control strategy. This study was conducted using a survey method from January to March 2020 at the Barito Kuala District, South Kalimantan. Thirty villages were randomly selected from each of the eight chosen subdistricts. Out of the twenty-six weed species identified, there were ten species of grasses, seven sedges, and nine broadleaves. The results showed that the weed species were dominated by Cyperus halpan, Eleocharis dulcis, and Cynodon dactylon (L.), with an SDR of 23.46, 16.73, and 10.03, respectively. The analysis of GC-MS showed that the weeds contained four similar compounds: neophyte diene, palmitic acid, linoleic acid, and stigmasterol. The largest compound content in C. halpan was diisocotyl phthalate (48.49%), while in E. dulcis and C. dactylon the largest were o-phthalic acid and mono-2-ethylhexyl-ester (69.36 and 40.23%). Moreover, weed allelochemicals are classified into fatty acids, steroids, esters, and other volatile compounds, where some have the potential for allelopathy that inhibits crop growth.

Bioassay-guided isolation and in silico study of antihyperlipidemic compounds from Onosma hispidum Wall

Isolation of bioactive compounds from plants and their therapeutic evaluation is crucial in the pursuit of novel phytochemicals and contributes an indispensable role in drug discovery and design. The literature has documented the hypolipidemic effect of numerous Onosma species. Taking that into consideration, the current study was designed to isolate, purify and evaluate the antihyperlipidemic potential of leaves of Onosma hispidum Wall. For the first time, the bioassay-guided isolation led to the separation of 3 compounds that were identified by spectroscopic techniques as o-phthalic acid bis-(2-ethyl decyl)-ester (1), bis (2-ethyloctyl) phthalate (2), and 1,2 benzenedicarboxylic acid bis(2-methyl heptyl) ester (3). Lipase inhibition assay was utilized to scrutinize the antihyperlipidemic potential of methanolic extract fractions and subsequently isolated compounds. Further, the isolated compounds were employed for in silico studies via molecular docking, molecular mechanics with generalized born and surface area solvation (MM-GBSA), and MD simulations with Pancreatic Lipase Colipase (PDB ID: 1LPB). Molecular docking and MM-GBSA of isolated compounds were employed to explain the mode of binding between the protein–ligand complex and binding free energy calculation, respectively. Since compound (3) displayed the best docking score of −6.689 kcal/mol as compared to orlistat −5.529 kcal/mol with PDB: 1LPB. So, it was chosen for MD simulations to evaluate ligand stability and flexibility of the complex which was validated by the fluctuation of α-carbon chain, root mean square deviation (RMSD), root mean square fluctuation (RMSF), and type of interactions involved which authenticated the in vitro lipase inhibitory potential. Overall, in silico and in vitro results validated that compound (3) could be exploited as a promising pancreatic lipase inhibitor. Communicated by Ramaswamy H. Sarma

Efficient and Reversible Separation of Chloroform from Chlorinated Hydrocarbons and Water Utilizing a Two-Dimensional Coordination Network.

Chloroform is a volatile organic solvent and a contaminant that is slightly soluble in water, making the reversible separation of chloroform from water a critical and challenging task within the chemical and environmental industries. In this study, we present a newly developed coordination framework, [Zn(4-pmntd)(opa)] [4-pmntd, N,N'-bis(4-pyridylmethyl)naphthalene diimide; opa, o-phthalic acid], which demonstrates a high adsorption capacity for chloroform (2.5 mmol/g) and an excellent ability to separate chloroform from water. The effectiveness of chloroform extraction by Zn(4-pmntd)(opa) was confirmed through vapor sorption, grand canonical Monte Carlo simulation, and 1H nuclear magnetic resonance spectroscopy. The porous framework was also utilized to create a filtration film using natural rubber, which successfully separated chloroform from water with a minimum test concentration of approximately 1 × 10-6 mol/L and a chloroform purity of 99.2%. [Zn(4-pmntd)(opa)] therefore has significant potential for low-energy separation and recycling of chloroform from water under ambient conditions.

Solvent effects of water on the decarboxylation of o-phthalic acid in supercritical water

Water's effect on o-phthalic acid decarboxylation was studied by varying the pressure from (20 to 40) MPa at (380, 400, and 420) °C. The rate constants decreased with increasing pressure at (400 and 420) °C, but remained nearly constant at 380 °C. The trends at (400 and 420) °C were explained using Kirkwood theory, which proposed preferential solvation of the reactant over the transition state. The 380 °C trend was thought to be explained by solvent inhomogeneities and water's peculiar behavior near the critical point. Solvent inhomogeneities were most likely responsible when rates remained low despite low dielectric constant values. These inhomogeneities could have caused a higher local dielectric constant around the solute, suppressing the rate in a manner similar to the higher-pressure region. Water, according to these findings, has the greatest influence on the reaction via solvation.

Biodegradation of Naphthalene and Anthracene by Aspergillus glaucus Strain Isolated from Antarctic Soil

Biotechnologies based on microbial species capable of destroying harmful pollutants are a successful way to solve some of the most important problems associated with a clean environment. The subject of investigation is the Antarctic fungal strain Aspergillus glaucus AL1. The culturing of the examined strain was performed with 70 mg of wet mycelium being inoculated in a Czapek Dox liquid medium containing naphthalene, anthracene, or phenanthrene (0.3 g/L) as the sole carbon source. Progressively decreasing naphthalene and anthracene concentrations were monitored in the culture medium until the 15th day of the cultivation of A. glaucus AL1. The degradation was determined through gas chromatography–mass spectrometry. Both decreased by 66% and 44%, respectively, for this period. The GC-MS analyses were applied to identify salicylic acid, catechol, and ketoadipic acid as intermediates in the naphthalene degradation. The intermediates identified in anthracene catabolism are 2-hydroxy-1-naphthoic acid, o-phthalic acid, and protocatechuic acid. The enzyme activities for phenol 2-monooxygenase (1.14.13.7) and catechol 1,2-dioxygenase (1.13.11.1) were established. A gene encoding an enzyme with catechol 1,2-dioxygenase activity was identified and sequenced (GeneBank Ac. No KM360483). The recent study provides original data on the potential of an ascomycete’s fungal strain A. glaucus strain AL 1 to degrade naphthalene and anthracene.

On the effects of organic-acids isomers on temperature-responsiveness in wormlike micelles (WLMs) systems

Responsive wormlike micelles (WLMs) consisted of cationic surfactants and organic-acids are fascinating due to their reversible molecular recognition properties. However, it is unknown how the structure of organic-acids alters the stimuli-responsiveness of WLMs systems. Herein, the peculiar nature of temperature-responsive behaviors in three WLMs systems were systematically investigated. These were manufactured by combining N-erucamidopropyl-N,N-dimethylamine (UC22AMPM) with isomers of organic-acids: o-phthalic acid (o-PA), m-phthalic acid (m-PA) and p-phthalic acid (p-PA) at molar ratio of 2:1 (named as o-EAPA, m-EAPA and p-EAPA respectively). The phase behaviors, macro- and micro-rheology, as well as the mechanism of temperature-responsiveness were explored by visual inspection, rheological and optical methods. The results showed that the three systems exhibited different responsiveness with increase of temperature. Among them, the viscosity and viscoelasticity of o-EAPA were gradually decreased with temperature increase from 30 °C to 90 °C. On the other hand, those of p-EAPA were firstly increased and subsequently decreased, exhibiting the highest viscosity during the heating process. This peculiar phenomenon was attributed to the hydrophilic difference of organic-acids isomers, leading to variations of micelle transitions upon temperature increase. This study is the first report of aromatic-acids isomers inducing different on temperature-responsiveness, and finding beneficial for the development of responsive WLMs for different applications.

Effect of NaOH molarities to the microstructure and sodium storage performance of the Sn-MOF derived SnO2 microporous rod

In this study, we demonstrated a facile method to prepare a novel SnO2 microporous rod with various microstructures by controlling NaOH molarities in precursor synthesis processes. Four different molarities of NaOH solution (0.005 M, 0.048 M, 0.12 M and 0.5 M) were used together with o-phthalic acid in Sn-MOF synthesis to determine the effect of ligand [o-C6H4 ] concentration on microstructure evolution. It was found that increasing NaOH molarity can effectively decrease the size of Sn-MOF rods. Then, the SnO2 microporous rods were obtained by calcinating the as-prepared Sn-MOF as microstructures. Under an optimized experimental condition (NaOH molarity of 0.12 M), the SnO2 rods shows a modest initial coulombic efficiency of 61.3% with a high reversible sodium storage capacity of 503 mAh g−1 after 150 cycles at 50 mA g−1. Moreover, an impressive reversible sodium storage capacity of 206 mAh g−1 can be obtained at long-term cycling performance (800 cycles at current density of 2 A g−1). Effects of morphologies to electrochemical performances have been further discussed in aspects of intrinsic resistance, pseudocapacitive contribution, surface area and porous structure and microstructural stability, and the enhanced electrochemical performance could be attributed to factors of enhanced pseudocapacitive charge contribution, optimized microstructures, and structural stability, which ensure the SnO2−0.12 M to have a good rate performance and cyclability. This nanoscale-engineering method adopted here could be a promising path to fabricate SnO2-based anodes with novel microstructures for sodium storage applications.

Integrated Multi-omics Investigations Reveal the Key Role of Synergistic Microbial Networks in Removing Plasticizer Di-(2-Ethylhexyl) Phthalate from Estuarine Sediments.

ABSTRACTDi-(2-ethylhexyl) phthalate (DEHP) is the most widely used plasticizer worldwide, with an annual global production of more than 8 million tons. Because of its improper disposal, endocrine-disrupting DEHP often accumulates in estuarine sediments in industrialized countries at submillimolar levels, resulting in adverse effects on both ecosystems and human beings. The microbial degraders and biodegradation pathways of DEHP in O2-limited estuarine sediments remain elusive. Here, we employed an integrated meta-omics approach to identify the DEHP degradation pathway and major degraders in this ecosystem. Estuarine sediments were treated with DEHP or its derived metabolites, o-phthalic acid and benzoic acid. The rate of DEHP degradation in denitrifying mesocosms was two times slower than that of o-phthalic acid, suggesting that side chain hydrolysis of DEHP is the rate-limiting step of anaerobic DEHP degradation. On the basis of microbial community structures, functional gene expression, and metabolite profile analysis, we proposed that DEHP biodegradation in estuarine sediments is mainly achieved through synergistic networks between denitrifying proteobacteria. Acidovorax and Sedimenticola are the major degraders of DEHP side chains; the resulting o-phthalic acid is mainly degraded by Aestuariibacter through the UbiD-dependent benzoyl coenzyme A (benzoyl-CoA) pathway. We isolated and characterized Acidovorax sp. strain 210-6 and its extracellular hydrolase, which hydrolyzes both alkyl side chains of DEHP. Interestingly, genes encoding DEHP/mono-(2-ethylhexyl) phthalate (MEHP) hydrolase and phthaloyl-CoA decarboxylase—key enzymes for side chain hydrolysis and o-phthalic acid degradation, respectively—are flanked by transposases in these proteobacterial genomes, indicating that DEHP degradation capacity is likely transferred horizontally in microbial communities.IMPORTANCE Xenobiotic phthalate esters (PAEs) have been produced on a considerably large scale for only 70 years. The occurrence of endocrine-disrupting di-(2-ethylhexyl) phthalate (DEHP) in environments has raised public concern, and estuarine sediments are major DEHP reservoirs. Our multi-omics analyses indicated that complete DEHP degradation in O2-limited estuarine sediments depends on synergistic microbial networks between diverse denitrifying proteobacteria and uncultured candidates. Our data also suggested that the side chain hydrolysis of DEHP, rather than o-phthalic acid activation, is the rate-limiting step in DEHP biodegradation within O2-limited estuarine sediments. Therefore, deciphering the bacterial ecophysiology and related biochemical mechanisms can help facilitate the practice of bioremediation in O2-limited environments. Furthermore, the DEHP hydrolase genes of active DEHP degraders can be used as molecular markers to monitor environmental DEHP degradation. Finally, future studies on the directed evolution of identified DEHP/mono-(2-ethylhexyl) phthalate (MEHP) hydrolase would bring a more catalytically efficient DEHP/MEHP hydrolase into practice.

Investigation of the properties of the brominated phthalate-containing system and determination of its application areas

The structure of a multicomponent system including phthalic acid esters has been studied using the methods of infrared spectroscopy and proton magnetic resonance. The obtained spectrograms are analyzed, indicating the presence of peaks corresponding to certain radicals present in the assumed structure of the main organic compounds of the multicomponent system. The presence of bromine atoms in the radicals of the molecules that make up the phthalate-containing system is established. The structure of the molecules of the basic component of the brominated system is shown. Spectral studies have confirmed the classical model of bromine addition at the site of double carbon-carbon bonds in the phthalate radical. It is established that the brominated multicomponent physico-chemical system is represented to a greater extent by esters of o-phthalic acid. The solubility parameter of the system under study is determined by the calculation method. The solubility parameter 35.3 (kJ/m3)0.5 was experimentally confirmed for a brominated phthalate-containing system. It is shown that the Small formula used to calculate the parameters of individual substances can be used to estimate the parameters of complex multicomponent systems. Polymer materials with the minimum values of deviations in the solubility parameter with the system under study, for which ~±1.5, are determined. It is established that the system under study can be used as an effective plasticizer of polybutyl acrylate, polyisoprene, polyvinyl chloride, and polyvinyl acetate.

Synthesis, structural elucidation, thermal and antimicrobial studies of a heteroleptic Cu(II) complex incorporating hydrogen phthalate and N,N,N′,N′-tetramethylethylenediamine

A copper(II) complex of N,N,N′,N′-tetramethylethylenediamine and o-phthalic acid, [Cu(tmen)(Hpht)2] (1) (where Hpht1− is the monoanion of o-phthalic acid and tmen is N,N,N′,N′-tetramethylethylenediamine), has been synthesized and structurally characterized by elemental combustion analysis, UV–Visible spectroscopy, FTIR spectroscopy, and single crystal X-ray crystallography. The CuN2O4 chromophore is defined by two nitrogens of N,N,N′,N′-tetramethylethylenediamine and four carboxylate oxygens of two Hpht1– groups, resulting in a highly distorted cis-octahedral coordination geometry, due to large Jahn–Teller distortion. The two Hpht1– groups coordinated to Cu(II) are in a cis disposition, and their four carboxylato-oxygen atoms from two different Hpht1– groups coordinate in an asymmetric chelating fashion. The crystal structure of this copper(II)-Hphthalate-tmen monomer is consolidated by O–H····O and C–H····O hydrogen bonds and C–H····π interactions. The antibacterial properties of 1 and two other complexes, [Cu(bipy)(cinn)(H2O)] (2) and [Cu(en)(sal)Cl] n (3), against strains Bacillus spizizenii, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus Aureus, and Aspergillus niger were also investigated.

Concentration-dependent photoluminescence carbon dots for visual recognition and detection of three tetracyclines.

Concentration-dependent photoluminescence carbon dots (CDs) have been successfully synthesized through the one-step hydrothermal treatment of o-phthalic acid and ethylenediamine. The CDs possessed higher fluorescence quantum yield, up to 39.22%, exhibiting distinguished optical property, water solubility, and stability. The CDs that emit strong blue-green fluorescence can visually identify and determine tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). TC quenched the fluorescence of CDs at 500nm owing to the inner filter effect; OTC behaved similarly, but the emission wavelength of CDs was red-shifted to 515nm. Inversely, once CTC was introduced to CDs solution, the fluorescence increased and the emission peak was blue-shifted to 450nm. Bandgap transition and electrostatic interaction were proposed to be the mechanisms for the detection of OTC and CTC by CDs. Wide linear relationships were established for TC, OTC, and CTC with the limits of detection to be 50nM, 36nM, and 373nM, respectively. Furthermore, the nanoscale probe constructed by this system has been applied to detect tetracyclines (TCs) in complex samples with satisfying recoveries (93.2-114%) and was designed as a portable test strip sensor for visually on-site TCs of honey sample screening. Accordingly, the preparation process of the nano fluorescent probe is simple and environmentally friendly, and the probe has a specific recognition ability for tetracyclines. The synthesized CDs in this work provide a new orientation for fast, effective, and visual real-time detection of tetracycline in actual samples.

Biodegradation and phytotoxicity assessment of phenanthrene by biosurfactant-producing Bacillus pumilus 1529 bacteria

ABSTRACTPhenanthrene is a toxic and mutagenic pollutant that can cause severe environmental and human health issues. The bioremediation of these polyaromatic hydrocarbons (PAHs) is possible with a biosurfactant by enhancing hydrophobicity. In this study, the production of a biosurfactant by Bacillus pumilus 1529 and its effects on the phenanthrene biodegradation pathway were examined. Biosurfactant production was determined using hemolytic activity, emulsification index, and surface tension. For phenanthrene metabolite detection, samples at 0, 7, 14, and 21 incubation days were analysed by gas chromatography-mass (GC-mass) spectrometry. The results showed that Bacillus pumilus 1529 can reduce surface tension to 22.83 ± 1.1 mN m−1. Furthermore, the GC-mass spectrometry analysis showed that 1-hydroxy-2-naphthoic acid, benzaldehyde, o-phthalic acid, and phenylacetic acid were notable phenanthrene metabolites produced during phenanthrene biodegradation. Biodegraded phenanthrene and its metabolites have a less toxic effect on the germination of safflower seeds than non-biodegraded phenanthrene. The IC50 of phenanthrene on seed germination after biodegradation was increased to approximately 113 mg L−1. In general, biodegradation aided by biosurfactant producing bacteria contributed to turning the toxic phenanthrene into less harmful metabolites with lower phytotoxicity effects, indicating that its application in the bioremediation of PAHs is promising.

Degradation of N-phenyl-2-naphthylamine by Rhizobium leguminosarum bv. viciae, Pseudomonas syringae pv. pisi, and Clavibacter michiganensis sps. sepedonicus Bacteria

The composition of aromatic compounds in the liquid culture medium and the cells of the Rhizobium leguminosarum bv. viciae, Pseudomonas syringae pv. pisi, and Clavibacter michiganensis sps. sepedonicus bacteria grown in the presence of the negative allelopathic compound N-phenyl-2-naphthylamine (N-PNA) found in the root exudates of legume plants is analyzed. It is demonstrated that phthalates are the main products of N-PNA degradation. Bacteria can actively secrete them into the environment and convert phthalates of one type into other types by changing the alkyl groups linked to the o-phthalic acid via the ester bond in their molecules. The analyzed bacteria differed in the rate of N-PNA degradation (10 and 100 µM), which exerted different effects on their growth and viability. The proposed mechanisms could potentially be used to control the bacterial composition and number in the rhizosphere of legume plants with N-PNA and phthalates secreted by plant roots into the exudates, as well as the phthalates produced in the course of N-PNA degradation in the bacterial cells.

Micellar and sub-micellar liquid chromatography of terephthalic acid contaminants using a C18 column coated with Tween 20.

The tremendous amounts of terephthalic acid (TPA) produced globally require consistent monitoring of its contaminants during the different stages of production for quality control purposes. In this paper, a simple, robust and green liquid chromatography method has been developed using an isocratic 100% aqueous mobile phase at pH 2 (dilute sulfuric acid) to separate TPA contaminants (mono-, di-, and tri-carboxylic aromatic acids) on a C18 stationary phase coated with Tween 20 (polyoxyethylene(20)sorbitan monolaurate). After optimization of all chromatographic conditions, near baseline separation of the nine carboxylic acids under investigation was achieved with a 2.5 mL/min flow rate on a 5 micron C18 silica column (100 x 4.6 mm) in under 20 min. The modified stationary phase showed an excellent capability to separate structural isomers in a reasonable time, markedly better that the bare C18 stationary phase. Plots of ln retention factor versus 1/temperature showed the expected linear relationship for the di- and tri-carboxylic aromatic acids (single retention mechanism likely) but a quadratic fit for the mono-carboxylic aromatic acids (dual retention mechanism likely). Due to the stability of the surfactant modified stationary phase, future potential mass spectrometry compatibility was shown through the alternative use of trifluoroacetic acid in the 100% H2O (no Tween) mobile phase but still with UV detection. The developed method with 0.001% (vol/vol) Tween in the mobile phase was successfully used to analyze two different types of TPA industrial samples for all nine components plus revealing some other impurity peaks. The lowest limit of detection was 0.010 nmoles for o-phthalic acid and p-toluic acid (PTA), while the highest was 0.065 nmoles for 4-carboxybenzaldehyde (CBA). The concentrations of these important contaminants, PTA and CBA, in the mother liquor sample were 3348mg/L and 1806mg/L, respectively, while their respective concentrations in the purified TPA powder were 135mg/kg and 17.7mg/kg.

Endogenous phthalates in plants and their alleged participation in defense response against phytopathogens

Endogenous phthalates (esters of o-phthalic acid) have been revealed in plant in situ and in vitro. Phthalates reduced biofilm formation and growth of Clavibacter michiganensis ssp. sepedonicus and changed morphology of colonies. So phthalates were considered to be a part of plant defense against bacterial phytopathogens. Meanwhile, phthalates have been found in the cells of phytopathogenic bacteria. It was suggested that the physiological and biochemical role of phthalates can be much more complex and not be limited to the participation of plant organisms in the protective process.

Rheological behaviors and mechanism of pH-stimulus wormlike micelles variation induced by ortho-substituent types of benzoic acid

pH-responsive wormlike micelles (WLMs) have been widely constructed by the mixture of surfactants and organic acids. However, the effect of different ortho-substituents on the rheological behaviors of WLMs remains unclear. Here in, three pH-responsive WLMs were prepared by combining N-erucamidopropyl-N, N-dimethylamine (UC22AMPM) with o-phthalic acid (o-PA), salicylic acid (HSal) and benzoic acid (BA) at the molar ratio of 2:1, respectively (named as o-EAPA, EAHSal, EABA). The phase behaviors, viscoelasticity and thickening mechanism were researched by macroscopic observation, rheological measurements, cryo-TEM, surface tension and 1H NMR. The results indicated that, the hydroxyl group at ortho position (HSal) could form the intramolecular hydrogen bond and prevented the rotation of carboxyl group, which decreased the steric hindrance of carboxyl group. Therefore, EABA system exhibited the weaker viscoelasticity than EAHSal system. The carboxyl group in ortho position (o-PA) can construct the “pseudo” Gemini surfactant by electrostatic attraction, and o-PA2− entered into aqueous phase due to its strong hydrophilicity, which further eliminated the steric hindrance of benzene ring. As a result, o-EAPA solution had the highest viscoelasticity among the three systems. In addition, by circularly changing the pH for several times, the three systems could maintain its original viscoelasticity without being weakened in the slightest.