Search Results (15)

Hexavalent chromium (Cr(VI)), a common contaminant in industrial wastewater, poses severe health risks due to its carcinogenic and mutagenic properties. Consequently, the development of efficient and environmentally friendly methods to reduce Cr(VI) to the less toxic trivalent chromium (Cr(III)) is of great importance. In this study, we present a cost-effective photocatalytic approach using graphitic carbon nitride (g-C₃N₄) modified with 1,3,5-trihydroxybenzene via one-step thermal condensation. The modified photo-catalyst exhibited improved surface area, porosity, visible-light absorption, and a narrowed band gap, all of which contributed to enhanced charge separation. As a result, nearly complete reduction in Cr(VI) was achieved within 90 min under visible-light irradiation. Further optimization of catalyst dosage and EDTA concentration gave even higher reduction efficiency. This work offers a promising strategy for the design of high-performance photocatalysts for environmental remediation. Full article

Metarhizium fungi, essential for ecosystem function and commonly utilised in pest control, often occupy ecological niches contaminated by toxic compounds of both anthropogenic and microbiological origin. The present study reveals the potential of Metarhizium anisopliae for biodegradation of the Fusarium mycotoxin zearalenone (ZEN), a common contaminant of crops that poses a significant threat to human and animal health due to its oestrogenic potential and toxicity. A key aspect of the pathway described is the degradation of ZEN by cleaving the lactone bond, which results in a significant reduction in mycotoxin toxicity, highlighting the fungus’s bioremediation potential. Furthermore, this study provides the first evidence of subsequent degradation of ZEN metabolites through progressive shortening of the aliphatic chain, primarily via alternating oxidation and demethylation, ultimately yielding trihydroxybenzene. Significantly, lactone bond cleavage occurred not only in ZEN itself but also in its reduced forms, the zearalanols, formed through the initial reduction of ZEN to zearalenols. Elevated mRNA levels of cytochrome P450 (CYP450) monooxygenases in M. anisopliae exposed to ZEN indicate their significant involvement in degradation mechanisms. Intriguingly, the inhibition of CYP450 activity resulted in a substantial shift in the quantitative ratio of α- and β-epimers of zearalenols and zearalanols. The observed alteration towards β-form production likely stems from the inhibition of other CYP450-dependent reactions, indirectly influencing ZEN reduction pathways—a particularly noteworthy finding. These insights are crucial for developing strategies to utilise M. anisopliae in the bioremediation of ZEN-contaminated areas. Full article

The potential for triatomic phenols to significantly advance organic chemistry and other fields makes their chloroacetylation and the synthesis of compounds based on chloroacetyl products highly relevant. This diversity enables the creation of novel materials, medicines, and specialized compounds. Chloroacetylation yields functional groups known as chloroacetyls, which can serve as versatile building blocks for further modifications. This offers a systematic approach to the synthesis of complex compounds, expanding the toolkit available to synthetic chemists. Researching novel synthetic pathways often leads to unexpected discoveries and fresh ideas. By exploring new reaction mechanisms, reactivity patterns, and applications, the study of chloroacetylation in the context of triatomic phenols can inspire scientific innovation. In analytical chemistry, phenols and oxycarboxylic acids are used to identify and quantify metal ions. Therefore, we decided to combine these two classes of compounds. Through synthesis, a wide variety of substances with unique structures and properties can be produced. The syntheses based on the topic “Chloroacetylation of trihydroxybenzenes and Syntheses Based on Chloroacetyl Compounds” are described in this article. O-chloroacetylation reactions were carried out in the presence of trihydroxybenzenes: benzene-1,2,3-triol, benzene-1,2,4-triol and chloroacetyl chloride. 4,4′,4″-(((benzene-1,2,3-triyltris(oxy))tris(2-oxoethane-2,1-diyl))tris(oxy))tris(2,3-dihydroxy-4-oxobutanoic acid) and 4,4′,4″-(((benzene-1,2,4-triyltris(oxy))tris(2-oxoethane-2,1-diyl))tris(oxy))tris(2,3-dihydroxy-4-oxobutanoic acid) were produced as a consequence of the nucleophilic exchange of chlorine atoms. The sodium salt of tartaric acid (sodium (2S,2R)-3-carboxy-2,3-dihydroxypropanoate) was present during the procedure. The solvent that was employed was dimethylformamide. Using contemporary physicochemical techniques, the structure of the substance that was produced as a result of the reaction was examined. Both the reaction’s mechanism and methods were examined. Full article

Ambient condition-determined chemical CO₂ fixation affords great promise for remitting the pressure of CO₂ release. The construction of a microporous environment easily captures CO₂ molecules around the reactive sites of the catalyst to reinforce the reaction process. Herein, multi-hydroxyl-containing hyper-crosslinked organic polymers (HCPs-OH-n) are synthesized by the polymerization of 1,4-dichlorobenzyl (DCX) and m-trihydroxybenzene in the monosaccharide form in a Friedel–Crafts alkylation hypercrosslinking process (FCAHP). By tuning the DCX ratio in the FCAHP, the structural properties can be regulated to create a more microporous surface in the HCPs-OH-n; meanwhile, the formed multi-hydroxyl species in the microporous environment could induce the easy interaction between hydroxyls and epoxides by forming a hydrogen bond, which improves the activation of epoxides during the cycloaddition reaction to synthesize the cyclic carbonates at ambient conditions. The structural properties suggest that HCPs-OH-n possess a large surface area with appreciable microporous and mesoporous distribution. As expected, the HCPs-OH-3 bearing the most abundant mesoporosity affords the highest reactivity in the chemical CO₂ fixation to cyclic carbonates and is endowed with rational recoverability. Full article

Bandgap and energy levels are crucial for developing new electronic and photonic devices because photoabsorption is highly dependent on the bandgap. Moreover, the transfer of electrons and holes between different materials depends on their respective bandgaps and energy levels. In this study, we demonstrate the preparation of a series of water-soluble discontinuously π-conjugated polymers through the addition–condensation polymerization of pyrrole (Pyr), 1,2,3-trihydroxybenzene (THB) or 2,6-dihydroxytoluene (DHT), and aldehydes, including benzaldehyde-2-sulfonic acid sodium salt (BS) and 2,4,6-trihydroxybenzaldehyde (THBA). To control the energy levels of the polymers, varying amounts of phenols (THB or DHT) were introduced to alter the electronic properties of the polymer structure. The introduction of THB or DHT into the main chain results in discontinuous conjugation and enables the control of both the energy level and bandgap. Chemical modification (acetoxylation of phenols) of the polymers was employed to further tune the energy levels. The optical and electrochemical properties of the polymers were also investigated. The bandgaps of the polymers were controlled in the range of 0.5–1.95 eV, and their energy levels could also be effectively tuned. Full article

In this study, the preparation of covalent polyoxometalate organic frameworks (CPOFs) is introduced using the idea of polyoxometalate and covalent organic frameworks. Firstly, the prepared polyoxometalate was functionalized with an amine group (NH₂-POM-NH₂), and then the CPOFs were prepared by a solvothermal Schiff base reaction with NH₂-POM-NH₂ and 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) as monomers. After the incorporation of PtNPs and MWCNTs into the CPOFs material, the PtNPs-CPOFs-MWCNTs nanocomposites, which possess excellent catalytic activity and electrical conductivity, were formed and utilized as new electrode materials for the electrochemical thymol sensors. The obtained PtNPs-CPOFs-MWCNTs composite exhibits excellent activity toward thymol, which is attributable to its large special surface area, good conductivity and the synergistic catalysis of each component. Under optimal experimental conditions, the sensor presented a good electrochemical response to thymol. The sensor shows two good linear relationships between the current and thymol concentration in the range of 2–65 μM (R² = 0.996) and 65–810 μM (R² = 0.997), with the corresponding sensitivity of 72.7 μA mM⁻¹ and 30.5 μA mM⁻¹, respectively. Additionally, the limit of detection (LOD) was calculated to be 0.2 μM (S/N = 3). At the same time, the prepared thymol electrochemical sensor revealed superior stability and selectivity. The constructed PtNPs-CPOFs-MWCNT electrochemical sensor is the first example of thymol detection. Full article

Fusobacterium nucleatum is a lesion-associated obligate anaerobic pathogen of destructive periodontal disease; it is also implicated in the progression and severity of colorectal cancer. Four genes (FN0625, FN1055, FN1220, and FN1419) of F. nucleatum are involved in producing hydrogen sulfide (H₂S), which plays an essential role against oxidative stress. The molecular functions of Fn1419 are known, but their mechanisms remain unclear. We determined the crystal structure of Fn1419 at 2.5 Å, showing the unique conformation of the PLP-binding site when compared with L-methionine γ-lyase (MGL) proteins. Inhibitor screening for Fn1419 with L-cysteine showed that two natural compounds, gallic acid and dihydromyricetin, selectively inhibit the H₂S production of Fn1419. The chemicals of gallic acid, dihydromyricetin, and its analogs containing trihydroxybenzene, were potentially responsible for the enzyme-inhibiting activity on Fn1419. Molecular docking and mutational analyses suggested that Gly112, Pro159, Val337, and Arg373 are involved in gallic acid binding and positioned close to the substrate and pyridoxal-5′-phosphate-binding site. Gallic acid has little effect on the other H₂S-producing enzymes (Fn1220 and Fn1055). Overall, we proposed a molecular mechanism underlying the action of Fn1419 from F. nucleatum and found a new lead compound for inhibitor development. Full article

The paper presents data on the study of the polycondensation of 2-furaldehyde and 1,3,5-trihydroxybenzene in an alkaline medium to obtain a plasticizing additive. Results are presented on the study of the products of the separate interaction of 1,3,5-trioxybenzene and 2-furaldehyde with NaOH, and the joint polycondensation of 1,3,5-trioxybenzene with 2-furaldehyde with NaOH by UV spectroscopy. The structure of the product of the interaction of 1,3,5-trioxybenzene with 2-furaldehyde in an alkaline medium was studied by IR spectroscopy. Stronger C–H bonds appear in the IR spectrum and stretching vibrations of the C = O group are not observed, which confirms the production of a new compound. The optimal dosage of the developed plasticizing additive has been established as 0.3% of the cement mass (calculated on dry matter). The developed plasticizing additive can significantly reduce the water-cement ratio while maintaining the strength characteristics of cement compositions. In addition, when using the additive, the strength characteristics are significantly increased with a reduced water-cement ratio. Full article

Trimeric acylphloroglucinols (T-ACPLs) are a subclass of the large class of acylphloroglucinols—derivatives of 1,3,5-trihydroxybenzene containing an R–C=O group. T-ACPL molecules contain three acylphloroglucinol moieties linked by methylene bridges. Many of them are present in natural sources and exhibit biological activities, often better than the corresponding activities of monomeric acylphloroglucinols. All the stable conformers of T-ACPLs contain seven intramolecular hydrogen bonds, which constitute the dominant stabilising factors. A total of 38 different T-ACPLs, including both naturally occurring and model molecules, have been calculated at the HF and DFT/B3LYP levels. The DFT/B3LYP calculations were carried out both without and with Grimme’s dispersion correction, to highlight the dispersion (and, therefore, also electron correlation) effects for these molecules. The roles of dispersion are evaluated considering the effects of Grimme’s correction on the estimation of the conformers’ energies, the description of the characteristics of the individual hydrogen bonds, the conformers’ geometries and other molecular properties. Overall, the results offer a comprehensive overview of the conformational preferences of T-ACPL molecules, their intramolecular hydrogen bond patterns, and the correlation effects on their properties. Full article

Phloroglucinols are characteristic constituents of Hypericumjaponicum that are claimed to exert several bioactivities, such as anti-inflammatory, anti-depressant and anti-viral ones. Phloroglucinols are unstable compounds and their synthesis is challenging; thus, isolation from natural sources is still one of the main strategies for obtaining these constituents in purified form. Assessing the presence of phloroglucinols in plant materials can be of interest for compound isolation, and LC-MS approaches afford sensitivity and specificity in this regard. In this work, we combined data from quadrupole-time of flight (QTOF) and ion trap (IT) mass spectrometers in order to assess the presence of the phloroglucinols characteristic of H. japonicum and to elucidate their MS fragmentation pathways. The identified compounds present similar structures bearing the 1,3,5-trihydroxybenzene core with different substitutions, which, in constituents at higher MW, is linked to 3′,3′-dimethyl-6′-oxo-phlorisobutyrophenone by a methylene bridge. Differences in MS² spectra of the considered phloroglucinols are useful for compound identification and differentiation, and to perform dereplication studies. Overall, the proposed approach could be useful for the analysis of phloroglucinols in H. japonicum and other plant species. Full article

The aromatic heterocyclic compound indole is widely spread in nature. Due to its floral odor indole finds application in dairy, flavor, and fragrance products. Indole is an inter- and intracellular signaling molecule influencing cell division, sporulation, or virulence in some bacteria that synthesize it from tryptophan by tryptophanase. Corynebacterium glutamicum that is used for the industrial production of amino acids including tryptophan lacks tryptophanase. To test if indole is metabolized by C. glutamicum or has a regulatory role, the physiological response to indole by this bacterium was studied. As shown by RNAseq analysis, indole, which inhibited growth at low concentrations, increased expression of genes involved in the metabolism of iron, copper, and aromatic compounds. In part, this may be due to iron reduction as indole was shown to reduce Fe³⁺ to Fe²⁺ in the culture medium. Mutants with improved tolerance to indole were selected by adaptive laboratory evolution. Among the mutations identified by genome sequencing, mutations in three transcriptional regulator genes were demonstrated to be causal for increased indole tolerance. These code for the regulator of iron homeostasis DtxR, the regulator of oxidative stress response RosR, and the hitherto uncharacterized Cg3388. Gel mobility shift analysis revealed that Cg3388 binds to the intergenic region between its own gene and the iolT2-rhcM2D2 operon encoding inositol uptake system IolT2, maleylacetate reductase, and catechol 1,2-dioxygenase. Increased RNA levels of rhcM2 in a cg3388 deletion strain indicated that Cg3388 acts as repressor. Indole, hydroquinone, and 1,2,4-trihydroxybenzene may function as inducers of the iolT2-rhcM2D2 operon in vivo as they interfered with DNA binding of Cg3388 at physiological concentrations in vitro. Cg3388 was named IhtR. Full article

In this work, the degradation and mineralization of Diallyl Phthalate (DAP) in water by Fenton oxidation was investigated. The effects of different experimental parameters including the initial pH, the hydrogen peroxide (H₂O₂) dose, the catalyst (Fe²⁺) dose, the iron source, and the DAP concentration on the rate and the yield of DAP degradation by Fenton oxidation were evaluated. DAP and its intermediates were quantified by high performance liquid chromatography (HPLC) analysis and the measurement of total organic carbon (TOC) during Fenton oxidation. The results obtained confirmed that hydroxyl radicals (HO^•) generated from Fenton’s reaction were capable of completely eliminating DAP from water. Fenton oxidation of 100 mg/L DAP aqueous solution at pH = 3.2 required 1000 mg/L H₂O₂ and 50 mg/L Fe²⁺. Under these conditions, more than TOC removal exceeded 95% after 300 min Fenton oxidation. The competition kinetics method was used to determine an absolute rate constant of 7.26.10⁹ M⁻¹ s⁻¹ for the reaction between DAP and HO^• radicals. HPLC analysis showed that phthalic acid, 1,2-dihydroxybenzene, 1,2,4-trihydroxybenzene, maleic acid, formic acid and oxalic acid were the main intermediates formed during DAP degradation. Accordingly, a simple DAP degradation mechanism by the Fenton reaction was proposed. These promising results proved the potential of Fenton oxidation as a cost-effective method for the decontamination of wastewaters containing phthalates. Full article

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene), which are unique compounds from marine brown algae. In our present study, a procedure for extraction and enrichment of phlorotannins from S. fusiforme with highly antioxidant potentials was established. After comparison of different extraction methods, the optimal extraction conditions were established as follows. The freeze-dried seaweed powder was extracted with 30% ethanol-water solvent with a solid/liquid ratio of 1:5 at temperature of 25 °C for 30 min. After extraction, the phlorotannins were fractioned by different solvents, among which the ethyl acetate fraction exhibited both the highest total phlorotannin content (88.48 ± 0.30 mg PGE/100 mg extract) and the highest antioxidant activities. The extracts obtained from these locations were further purified and characterized using a modified UHPLC-QQQ-MS method. Compounds with 42 different molecular weights were detected and tentatively identified, among which the fuhalol-type phlorotannins were the dominant compounds, followed by phlorethols and fucophlorethols with diverse degree of polymerization. Eckol-type phlorotannins including some newly discovered carmalol derivatives were detected in Sargassum species for the first time. Our study not only described the complex phlorotannins composition in S. fusiforme, but also highlighted the challenges involved in structural elucidation of these compounds. Full article

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4–12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds. Full article

Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10) at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction media by light. The principal reaction products are typical of other oxidative degradation processes of quercetin, namely 3,4-dihydroxy-benzoic (proto-catechuic) and 2,4,6-trihydroxybenzoic (phloroglucinic) acids, as well as the decarboxylation product of the latter – 1,3,5-trihydroxybenzene (phloroglucinol). In accordance with the literature data, this process involves the cleavage of the γ-pyrone fragment (ring C) of the quercetin molecule by oxygen, with primary formation of 4,6-dihydroxy-2-(3,4-dihydroxybenzoyloxy)benzoic acid (depside). However under such mild conditions the accepted mechanism of this reaction (oxidative decarbonylation with formation of carbon monoxide, CO) should be reconsidered as preferably an oxidative decarboxylation with formation of carbon dioxide, CO2. Direct head-space analysis of the gaseous components formed during quercetin oxidation in aqueous solution at ambient temperature indicates that the ratio of carbon dioxide/carbon monoxide in the gas phase after acidification of the reaction media is ca. 96:4 %. Oxidation under these mild conditions is typical for other flavonols having OH groups at C3 (e.g., kaempferol), but it is completely suppressed if this hydroxyl group is substituted by a glycoside fragment (as in rutin), or a methyl substituent. An alternative oxidation mechanism involving the direct cleavage of the C2-C3 bond in the diketo-tautomer of quercetin is proposed. Full article