Benzothiazole Research Articles

Prenatal exposure to benzotriazoles and benzothiazoles and child neurodevelopment: A longitudinal study

Benzotriazoles (BTRs) and benzothiazoles (BTHs) are emerging benzo-heterocyclic compounds that may induce neurotoxicity. However, the effect of prenatal exposure to BTs (BTRs and BTHs) on child neurodevelopment has not been elucidated. We aimed to explore the associations between maternal urinary concentrations of BTs in single or in mixture with child neurodevelopment at the age of two. This study recruited 513 mother-child pairs based on a birth cohort from 2014 to 2015 in Wuhan. Maternal urinary concentrations of eight BTs (four BTRs and four BTHs) in the first, second, and third trimesters were measured. The mental development index (MDI) and psychomotor development index (PDI) of children, as two indexes of neurodevelopment, were assessed at two years old by the Bayley Scales. In the analyses of single BTs, prenatal average tolyltriazole (TTR) exposure level was associated with decreased boys' MDI scores (β = −2.84, 95 % CI: −5.11, −0.57) and prenatal average 1-H-benzotriazole (1-H-BTR) exposure level was associated with decreased boys' PDI scores (β = −1.44, 95 % CI: −2.70, −0.17), respectively. Maternal urinary concentrations of benzothiazole (BTH) in the 1st trimester (β = −1.79, 95 % CI: −2.78, −0.80), 2nd trimester (β = −1.14, 95 % CI: −2.19, −0.09), and the prenatal average exposure (β = −2.15, 95 % CI: −3.69, −0.61) were also negatively associated with boys' PDI scores. However, no significantly negative association was observed among girls. In the further mixture analysis, the quantile g-computation model found a significant negative association between prenatal average concentrations of BTs in mixture and boys' PDI scores [β = −4.80 (95 % CI: −9.08, −0.52)], and BTH weighted the highest in the negative association. As far as we know, this is the first research to estimate the effect of prenatal exposure to BTs on child neurodevelopment. The findings showed that prenatal exposure to BTs was negatively associated with neurodevelopment among boys, suggesting that the associations may be modified by infant sex.

Computational Studies to Identify Potential Inhibitors Targeting the DprE1 Protein in Mycobacterium tuberculosis

Background: DprE1, which is a flavoenzyme, is very important for cell wall biosynthesis in Mycobacterium tuberculosis (Mtb) and for the pathogenesis, virulence, lethality, and stress resistance of the host. Drug-resistant tuberculosis is a challenging global human health issue, necessitating the development of novel, more effective treatment regimens without adverse effects. DprE1 represents a potential therapeutic target. It was explored as a drug target utilizing benzothiazoles (BTZ), which are enormously potential anti-bacterial agents and are currently being explored as anti-mycobacterial entities. Materials and Methods: We used virtual screening of bioactive molecules from PubChem and ZINC databases targeting DprE1, having bioactive thousands of molecules known for anti-microbial activity. In the present study, we selected 100 compounds as the most promising candidates to act as potential DprE1 inhibitors to control this emerging condition of tuberculosis infection. To identify the six topranked compounds, molecular docking was used to calculate the binding affinities (ranging from -8.3 to 10.0 kcal/mol) between various compounds (C1-C6) and the DprE1 protein. Results: Based on the results of an ADMET analysis, these six chemicals are safer potential drug candidates, as neither AMES toxicity nor carcinogenicity is present when toxicological properties are considered. Out of 6 compounds, the top-ranked compound exhibiting the best binding affinity against the drug target DprE1 (Pdb-id;4FEH) receptor was further subjected to molecular dynamic simulation for 100 nanoseconds to check the stability and trajectories by root-mean-square deviation (RMSD) and root-mean-square fluctuation (RMSF) graphs and interacting coordinates using Desmond Schrodinger Software. Conclusion: Our in-silico investigation identified potent inhibitors for the DprE1 protein of Mtb, and these compounds can be considered and recommended as the lead molecules in the treatment of tuberculosis.

High‐Performance Organic Photosynaptic Transistors Using Donor−Acceptor Type and Crosslinked Core−Shell Nanoparticles as a Floating Gate Electret

AbstractPhotosynaptic transistor is considered to be a potential candidate for breaking the von Neumann bottleneck in photo‐communication field. Herein, a series of donor−acceptor type and crosslinked core−shell nanoparticles are designed and applied in phototransistors as a charge‐trapping electret. The outer shell is composed of poly(ethylene glycol) methyl ether methacrylate (PEGMA); while the inner core comprises donors of thiophene and bithiophene (2T) and acceptors of benzothiazole (BT), naphthalenediimide (NDI), and hexafluorobenzene‐naphthalenediimide (FB‐NDI). It is found that the core−shell and donor−acceptor design play an important role in the charge trapping, photoresponse, and the corresponding device performance. Accordingly, the phototransistor comprising the crosslinked core−shell nanoparticles with a donor of 2T and an acceptor of BT (PV2T‐BT) produced the highest memory ratio of 105 over 104 s at a high operating voltage of −40 V. Meanwhile, the same device presented the highest paired‐pulse facilitation ratio of 168% at a medium operating voltage of −1 V, and an ultra‐low energy consumption of 0.0324 fJ at a low operating voltage of −1 µV. The findings in this study provide a new perspective on material design for phototransistor devices.

Synthesis of a polymerizable aggregation-induced emission (AIE) dye with A-D structure based on benzothiadiazole for fluorescent nanoparticles and its application in bioimaging

In recent years, fluorescent materials with aggregation-induced emission (AIE) have been receiving widespread attention in diverse fields due to their unique characteristics. In this work, a novel AIE fluorescent dye TTPA with electron acceptor–donor (A-D) structure were fabricated through Suzuki coupling and Knoevenagel condensation reaction using benzothiazole (BTA) and 4-(1,2,2-triphenylvinyl) benzaldehyde (TPB) as main components, and its maximum emission wavelength was about at 524 nm, otherwise, on the basis of the quantum calculations, the energy difference ΔE between HOMO and LUMO of TPB and TTPA were about 3.63 eV and 2.81 eV, respectively. The obtained TTPA dye with AIE feature could emit fluorescence in THF owing to the electron A-D structure and intramolecular charge transfer (ICT) effect. Subsequently, the amphiphilic fluorescent copolymers PEG-PA were synthesized through the RAFT polymerization of TTPA and PEGMA with various feeding ratios. The molecular weight (MW) and molecular weight distribution (Ð) of PEG-PA1 were about 1.8 × 104 and 1.30, respectively. According to the 1H NMR spectra, the molar proportion of TTPA in PEG-PA increased from 18.5 % to 26.6 % when the proportion of TTPA in the reactants increased from 20.0 % to 25.0 %. Moreover, the as-prepared PEG-PA copolymers would self-assemble into nanoparticles with 150–200 nm diameter in a water solution due to their amphiphilic property, which exhibited the prospective bioimaging application with many advantages such as hypotoxicity, good biocompatibility, and excellent cells penetration.

Aquatic environmental fates and risks of benzotriazoles, benzothiazoles, and p-phenylenediamines in a catchment providing water to a megacity of China

Wearing of vehicle parts could release many chemical additives into the environment, such as benzotriazoles (BTRs), benzothiazoles (BTHs), and p-phenylenediamines (PPDs), which are potentially toxic to wildlife and humans. This study investigated the occurrence, source, and risks of BTRs, BTHs, and PPDs in a source catchment providing water to Guangzhou, a megacity in South China, covering groundwater, surface water, and stormwater. The results showed that BTRs and BTHs were predominant in surface water and groundwater. Unexpectedly, the BTR and BTH concentrations were lower in surface water than groundwater in a third of the paired samples. For the first time, 6PPD-quinone, a toxic ozonation product of N-(1,3-dimethylbutyl)-N′-phenyl-1,4-phenylenediamine (6PPD), was extensively detected in source waters. Stormwater decreased the BTR concentrations but increased the 6PPD-quinone concentrations in surface water owing to their affiliation to suspended particles. From natural to urban segments of Liuxi river, a downstream increasing trend in BTR and BTH concentrations was observed, confirming that they are indicative of urban anthropogenic activities. Strong correlations between industrial activities and BTR or BTH concentrations in surface water indicated that industrial activities were their main sources. Six compounds were prioritized as potentially persistent, mobile, and toxic (PMT) chemicals, combing our monitoring results and REACH criterion. This study improves our understanding of the environmental fates and risks of water-soluble tire-wear chemicals, which provides important information for chemical management, and indicates attention should be paid to the risk posed by 6PPD-quinone in the source water.

Occurrence and removal of benzotriazole and benzothiazole in drinking water treatment plants

The occurrence and removal of four benzotriazoles (BTRs) and five benzothiazoles (BTHs) in drinking water treatment plants (DWTPs) and bottled water were investigated. The mean total BTR and BTH concentrations were 390 and 117 ng/L in raw water, 51.2 and 66.5 ng/L in treated water, and 0.758 and 48.4 ng/L in bottled water, respectively. Different distribution patterns were observed according to the water type, with the dominant BTR being 1H-BTR (mean: 57.8%) in raw water and a predominance of BTH in bottled water (mean: 84.6%). In the DWTPs, the mean removal of BTRs (90.9%) was better than that of BTHs (29.3%). The BTRs were efficiently removed in DWTPs, and in particular during adsorption processes. 5Cl-BTR had a high removal efficiency (75.7%) in the adsorption processes, followed by 5M-BTR (70.0%), 5,6-di-MeBTR (58.4%), and 1H-BTR (50.1%). By contrast, BTHs were not efficiently removed in DWTPs, although relatively high removal efficiencies were achieved with an ozonation process (43.1%) compared to other treatment processes. In treated drinking and bottled water, the hazard quotients (HQs) of the representative BTRs and BTHs were acceptable (defined as HQ < 1), with a safety margin of 2–5 orders of magnitude.

Theoretical SERS study of the strength and suitability of Cu12 nanostar for SERS: Complete theoretical studies, coinage metal SM12 comparisons, benzothiazole (BTH) adsorbent

Theoretical calculations were used to optimize molecular structures which help determine binding energies, and elucidate electronic properties of unsubstituted benzothiazole (BTH) adsorption on metal star models, SM12 (M = Ag/Au/Cu). BTH tends to connect via its donor nitrogen and sulfur heteroatoms as well as the π-conjugated carbon atoms; adsorption is onto the bare metal atoms of the nanostar, a single 12-membered ring, involving increasingly stable adsorption energies of −3.25/-5.71/-17.57 kcal mol−1 for BTH-Ag12/Au12/Cu12 complexes as one ascends the Group 11 triad. From the electrophilicity values, it is clear that the outermost electrons of the system will be able to travel (injected) from the chemically adsorbed BTH unit into the adsorbent SM12 within the structure of the complex. The values for changes in enthalpy and entropy for all complexes studied herein show that the motion of the atoms is constrained due to the presence of the BTH; the adsorption of BTH onto the investigated SM12 adsorbents is spontaneous. The increase of dipole moments for the complexes in aqueous media support potential for molecular recognition; drug delivery-oriented applications of the complexes are predicted to undergo dissolution in polar media such as water, offering the possibility for drug molecule recognition applications. Raman inactive modes of BTH become active within the BTH-metal complexes and experience enhancement in intensity. Adsorption behavior and thermodynamics parameters also indicate that the Cu12 cluster has the strongest interaction with maximum adsorption energy of −17.6 kcal mol−1. Density of states spectral analysis supports the charge transfer, adsorption behavior, and other thermodynamic parameters. In conclusion, density functional theory (DFT) has helped to determine electronic characteristics of SM12 clusters which have been demonstrated to be highly sensitive to the presence of BTH; these findings can allow for the molecular pairs to be used in (bio) sensor devices and to potentially trace the drug in the human body via spectrophotometry.

Synthesis and Biological Importance of 2-(thio)ureabenzothiazoles.

The (thio)urea and benzothiazole (BT) derivatives have been shown to have a broad spectrum of biological activities. These groups, when bonded, result in the 2-(thio)ureabenzothizoles (TBT and UBT), which could favor the physicochemical and biological properties. UBTs and TBTs are compounds of great importance in medicinal chemistry. For instance, Frentizole is a UBT derivative used for the treatment of rheumatoid arthritis and systemic lupus erythematosus. The UBTs Bentaluron and Bethabenthiazuron are commercial fungicides used as wood preservatives and herbicides in winter corn crops. On these bases, we prepared this bibliography review, which covers chemical aspects of UBTs and TBTs as potential therapeutic agents as well as their studies on the mechanisms of a variety of pharmacological activities. This work covers synthetic methodologies from 1935 to nowadays, highlighting the most recent approaches to afford UBTs and TBTs with a variety of substituents as illustrated in 42 schemes and 13 figures and concluded with 187 references. In addition, this interesting review is designed on chemical reactions of 2-aminobenzothiazoles (2ABTs) with (thio)phosgenes, iso(thio)cyanates, 1,1′-(thio)carbonyldiimidazoles [(T)CDI]s, (thio)carbamoyl chlorides, and carbon disulfide. This topic will provide information of utility for medicinal chemists dedicated to the design and synthesis of this class of compounds to be tested with respect to their biological activities and be proposed as new pharmacophores.

Push-pull electronic effects on benzothiazole derived probes for the detection of Zn2+: Exploring the sensing strategies and its applications

The diverse polarity of electron-donating 4-(diethylamino)salicylaldehyde (S-D), and electron-withdrawing 4-nitrosalicylaldehyde (S–W) were conjugated with benzothiazole (BT) to develop BTS-D and BTS-W probes, respectively. The probes exhibited the excited-state intramolecular proton transfer and intramolecular charge transfer sensing mechanisms in detecting Zn2+. BTS-D and BTS-W achieved a quantitative detection of Zn2+ followed by a strong cyan to green in the emission spectra, and from colorless to yellow in the UV–Vis spectra, respectively. The sensing pathways and coordination affinities between the probes and Zn2+ were explored using a series of spectroscopic evaluations, 1H NMR, 1H–1H COSY (2D NMR), HR–MS, XPS and DFT calculations. The probes demonstrated excellent selectivity, good water solubility, and high sensitivity, securing low LOD values: 0.15 μM for BTS-W in colorimetric analysis and 14 nM for BTS-D in fluorimetric analysis in aqueous media. The advantages of the probes assessed for the detection of Zn2+ in various water samples, Whatman paper-based sensor strips, and PC3 live cells. The findings revealed the encouraging on-site visualization in wastewater systems and bio-contents.

Theoretical studies on donor–acceptor based macrocycles for organic solar cell applications

We have designed a series of new conjugated donor–acceptor-based macrocyclic molecules using state-of-the-art computational methods. An alternating array of donors and acceptor moieties in these macrocycle molecules are considered to tune the electronic and optical properties. The geometrical, electronic, and optical properties of newly designed macrocyclic molecules are fully explored using various DFT methods. Five conjugated macrocycles of different sizes are designed considering various donor and acceptor units. The selected donor and acceptors, viz., thiophene (PT), benzodithiophene (BDT), dithienobenzodithiophene (DTBDT), diketopyrrolopyrrole (DPP), and benzothiazole (BT), are frequently found in high performing conjugated polymer for different organic electronic applications. To fully assess the potential of these designed macrocyclic derivatives, analyses of frontier molecular orbital energies, excited state energies, energy difference between singlet–triplet states, exciton binding energies, rate constants related to charge transfer at the donor–acceptor interfaces, and electron mobilities have been carried out. We found significant structural and electronic properties changes between cyclic compounds and their linear counterparts. Overall, the cyclic conjugated D–A macrocycles’ promising electronic and optical properties suggest that these molecules can be used to replace linear polymer molecules with cyclic conjugated oligomers.

The performance and pathway of benzothiazole degradation by electron beam irradiation.

Benzothiazole (BTH) is a typical refractory heterocyclic compound that can be used as a photosensitive material in organic synthesis and conditional plant resource research. The extensive use of BTH has led to high BTH concentrations in natural environment, such as in tap water and urine, which tend to inhibit animal hormone synthesis and induce genotoxicity. Traditional wastewater treatment processes cannot effectively remove BTH. Therefore, we aimed to use the electron beam method, an emerging method for pollutant degradation, to degrade BTH in water. Experiments showed that BTH can be effectively degraded (up to 90%) when the electron beam reaches 5kGy and irradiation conformed perfectly to the pseudo first-order kinetics model. Experimental results showed that acidic conditions are more favorable for electron beam degradation of BTH, while the degradation of most other inorganic ions is inhibited (except SO42-). Hydroxyl radicals (•OH) was confirmed to play a major role in degradation by the experiment, and the mineralization rate was greatly increased by the addition of H2O2 and K2S2O8. In addition, our experimental and theoretical calculations showed that the degradation of BTH occurred mainly through the opening of the benzene ring. Theoretical calculations showed that the toxicity of BTH decreased significantly after electron beam degradation, making it an effective way to degrade BTH.

5,6-Dihydroxyindole eumelanin content in human skin with varying degrees of constitutive pigmentation.

Human skin contains two distinct components: brown to black, insoluble eumelanin and light colored, alkaline-soluble pheomelanin. Eumelanin consists of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) moieties, while pheomelanin consists of benzothiazine (BT) and benzothiazole (BZ) moieties. These melanin monomer units can be quantitatively analyzed through specific degradation products by high-performance liquid chromatography (HPLC). Alkaline hydrogen peroxide oxidation (AHPO) of eumelanin gives rise to pyrrole-2,3,5-tricarboxylic acid (PTCA) and pyrrole-2,3-dicarboxylic acid (PDCA) as specific degradation products of the DHICA and DHI moieties, respectively. BZ moiety in pheomelanin can be analyzed as thiazole-2,4,5-tricarboxylic acid (TTCA). By reductive hydrolysis with hydroiodic acid, BT moieties in pheomelanin can be analyzed as 4-amino-3-hydroxyphenylalanine (4-AHP). As a recently improved AHPO-HPLC method enabled a better characterization of PDCA, this prompted us to address the question of DHI to DHICA ratio in human skin samples with varying degrees of constitutive pigmentation ranging from very light to dark. Results showed for the first time the ratio of 4 moieties: DHI 35%, DHICA 41%, BZ 20%, and BT 4%. The ratio is constant regardless of the degree of pigmentation. The high content of DHICA moiety may impart an antioxidant property to the epidermis melanin.

Development and validation of a simultaneous method for the analysis of benzothiazoles and organic ultraviolet filters in various environmental matrices by GC-MS/MS.

The presence of benzothiazoles (BTHs) and organic ultraviolet filters (UV filters) in aquatic ecosystems has emerged as a significant environmental issue, requiring urgent and efficient determination methods. A new, rapid, and sensitive determination method using gas chromatography triple quadrupole mass spectrometer (GC-MS/MS) was developed for the simultaneous extraction and analysis of 10 commonly used BTHs and 10 organic UV filters in surface water, wastewater, sediment, and sludge. For aqueous samples, solid-phase extraction (SPE) method was employed with optimizing of SPE cartridge type, pH, and elution solvent. For solid samples, ultrasonic extraction-solid-phase extraction purification (UE-SPE) and pressurized liquid extraction (PLE) methods were compared. And extraction conditions for ultrasonic extraction method (extraction solvents and extraction times) and PLE method (extraction temperatures and extraction cycles) were optimized. The limits of quantification for the 20 target compounds in surface water and wastewater were 0.01-2.12ng/L and 0.05-6.14ng/L, while those for sediment and sludge with UE-SPE method were 0.04-5.88ng/g and 0.22-6.61ng/g, respectively. Among the 20 target compounds, the recoveries ranged from 70 to 130% were obtained for 16, 15, 15, and 15 analytes in the matrix-spiked samples of surface water, wastewater, sediment, and sludge with three levels, respectively. And the precision was also acceptable with relative standard deviation (RSD) below 20% for all analytes. The developed methods were applied for the determination and quantification of target compounds in surface water, sediment, wastewater, and sludge samples collected from two wastewater treatment plants (WWTPs) and the Pearl River in Guangzhou, China. BTHs were frequently detected in surface water and wastewater, while UV filters were mainly found in sediment and sludge. Benzotriazole (BT) and 2-hydroxybenzothiazole (2-OH-BTH) were the two major BTHs in influent wastewater and surface water, respectively, with concentrations up to 966 and 189ng/L. As for sediment and sludge, 2-(2'-hydroxy-5'-octylphenyl)-benzotriazole (UV-329) was a predominant chemical, detected at concentrations of 111 and 151ng/g, respectively.

Distribution patterns of rubber tire-related chemicals with particle size in road and indoor parking lot dust

In recent years, concerns have arisen from the chemicals incorporated into tire material which are of potential to leach with the tire and road wear particles (TRWP) into the environment. In this study, the distributions of substituted benzothiazoles (BTHs) and p-phenylenediamines (PPDs), two groups of representative TRWP-related chemicals, were investigated in various size fractions (<20, 20–53, 53–125, 125–250, 250–500, 500–1000 μm) of dust samples from open roads and indoor parking lots in the urban region of Guangzhou (Guangdong, China). Mass weight distribution of the dust samples showed that fractions of <250 μm accounted for >72% of the total dust in both microenvironments. Widespread occurrence was observed with >80% detection frequency for almost all target compounds in all the particle fractions. Concentrations of BTHs and PPDs were similar between the two dust matrices. In addition, the newly defined transformation product of 6PPD, 6PPD-Q was at the median concentration of 122 ng/g in road dust and 154 ng/g in indoor parking lot dust. Overall, concentrations of the target BTHs and PPDs varied in different size fractions, which were mostly dominated in fine particle sizes (<53 μm). Specially, >70% of the target compounds were in the size fractions of <250 μm, suggesting the necessity of using <250 μm fractions of particles for monitoring and evaluating contamination levels and exposure risks of BTHs and PPDs from dust in future studies.

Regiodivergent Synthesis of Benzothiazole‐Based Isosorbide Imidates by Oxidative N‐Heterocyclic Carbene Catalysis

AbstractA novel N‐heterocyclic carbene (NHC)‐promoted regiodivergent protocol for exo (2‐OH) and endo (5‐OH) isosorbide (IS) imidates synthesis is described. The disclosed strategy allows the straightforward synthesis of monoimidate‐isosorbides (MIIs) endowed with the biologically relevant benzothiazole (BTA) moiety under mild oxidative conditions, starting from easy‐accessible aldimines. Process optimization encompassed the use of stoichiometric diquinone as well as atmospheric oxygen as oxidant species, focusing on reaction dichotomy between oxidative and oxygenative pathways. The reaction scope was investigated on a representative selection of BTA‐containing aldimines and further extended to congeners bearing different biologically pivotal N‐heterocyclic rings (benzoxazole, thiazole and isoxazole), observing good levels of yield (up to 87 %) and regioselectivity (exo/endo up to 10.0; endo/exo up to 7.0). Furthermore, the employment of an immobilized‐NHC under heterogeneous conditions was assessed, showing satisfactory selectivity towards exo‐MIIs (exo/endo=3.8). Overall, the methodology presented provided an unprecedented collection of high value‐added products with potential applications in different fields.

Associations of benzotriazoles and benzothiazoles with estrogens and androgens among pregnant women: A cohort study with repeated measurements

People are extensively exposed to benzotriazoles (BTRs) and benzothiazoles (BTHs) derivatives, which are environmental pollutants that may possess endocrine-disrupting potential; however, no epidemiological evidence is available on the associations of BTRs and BTHs with estrogens and androgens. This study aimed at investigating the associations of BTRs and BTHs with estrogens and androgens among pregnant women. Based on a prospective cohort study, we included 459 pregnant women who donated a complete serial of urine samples at each trimester and had repeated measurements of four BTRs, four BTHs, three estrogens (estrone, 17β-estradiol, and estrio), and two androgens (dehydroepiandrosterone and testosterone) in the urine samples. Associations of repeatedly measured BTRs and BTHs with maternal urinary estrogens and androgens were analyzed, and the cross-sectional associations were also analyzed. Tolyltriazole (TTR) (≥59.3%) and benzothiazole (BTH) (≥93.5%) had the highest detection rate among the BTRs and BTHs, respectively. Repeated measurement analysis and cross-sectional analysis consistently found the target BTRs and BTHs were positively associated with 17β-estradiol, estriol, and testosterone, while the trend of the associations with estrone and dehydroepiandrosterone was inconsistent. Among the positive associations with 17β-estradiol, estriol, and testosterone, the percent of change in estriol associated with TTR was the most prominent [28.5% (95% confidential interval: 24.2%, 32.9%) for each doubling in TTR]. The significant associations with estrone, estriol, testosterone, and dehydroepiandrosterone were stronger among pregnant women who gave birth to a boy than those who gave birth to a girl. These findings add epidemiological evidence on the endocrine-disrupting potential of BTRs and BTHs and highlight the importance of focusing on the health outcomes of BTRs and BTHs related to disturbed estrogens and androgens. Future studies are needed to validate these findings and explore the underlying mechanisms.

Green methodology based on active air sampling followed by solid phase microextraction and gas chromatography-tandem mass spectrometry analysis to determine hazardous substances in different environments related to tire rubber

A fast, efficient, and simple air sampling methodology was developed to study a high number of volatile and semivolatile organic compounds in air above tire rubber materials and surfaces made of recycled tire rubber. The proposed method, based on active sampling (solid-phase extraction, SPE) using a small quantity of sorbent material (25 mg) followed by solid-phase microextraction (SPME) and gas chromatography-tandem mass spectrometry analysis, was developed with the aim of determining 40 organics substances including polycyclic aromatic hydrocarbons (PAHs), plasticizers, antioxidants, and vulcanization agents. An experimental design was carried out to study the influence of main factors such as type of SPME fibre, solvent addition, headspace volume, stirring, as well as the factor interactions. Method performance showed good linearity in a broad concentration range (0.05 to 200 ng m−3, for most compounds), with coefficients of determination (R2) higher than 0.9900. Whole method precision (≤ 16 %) and accuracy were also satisfactory, obtaining quantitative recoveries (mean values between 80 and 110 % in most cases). Limits of detection and quantification have also been calculated, yielding values of sub ng m−3 for most compounds. The validated method was applied to outdoor and indoor air environments including playgrounds, football pitches and warehouses showing the presence of most target compounds in the samples achieving high levels for some PAHs (concentrations up to 51 ng m−3), benzothiazole (BTZ), diisobutyl- dibutyl- and di-(2-ethylhexyl)- phthalate, among others, reaching concentrations up to hundreds of ng m−3 (BTZ). This is the first time that the combination of techniques SPE and SPME is applied for these families of chemicals, and it is also the first time that this approach is proposed for the simultaneous multiclass compound extraction of substances of different chemical families. The whole sampling and extraction procedure is performed in a short period of time (61 min) allowing high throughput. The elimination of the use of organic solvents and waste generation by using only 25 mg of sorbent and a SPME fibre than are both reused makes the method sustainable and in consonance with the principles of the green chemistry. The method can be implemented in any routine lab and easily automated using a SPME autosampler.

An efficient low melting mixture mediated green approach for the synthesis of 2-substituted benzothiazoles and benzimidazoles

Benzothiazole (BTA) and benzimidazole (BIA) derivatives are unique structures having extensive applications in material sciences, medicinal chemistry, and supramolecular chemistry in addition to their immense utilization in diverse fields, which provide sufficient impetus to develop facile synthetic methods. Bearing the prominence of these vital scaffolds in mind, herein we revealed a simple yet straightforward method without involving any external catalyst as well as conventional volatile organic solvent to assemble a vast variety of 2-substituted BTA/BIA derivatives through the condensation of 2-aminobenzenethiol and/or o-phenylenediamine with aliphatic/aromatic aldehydes in presence of low melting mixtures. In this study, although, diverse deep eutectic mixtures were tested but N,N′-dimethyl urea (DMU) with L-(+)-tartaric acid (TA) in 7:3 ratio and citric acid (CA) with DMU in 4:6 ratio were found to be the best choices. Hopefully, the present method will be useful to generate diverse heterocyclic systems and will boost the applicability of deep eutectic mixtures in modern organic syntheses.

Benzothiazole-decorated iridium-based nanophotosensitizers for photodynamic therapy of cancer cells.

Photodynamic therapy (PDT) is an effective non-invasive treatment for tumors. The structure of a photosensitizer has an important influence on light utilization and efficiency of singlet-oxygen generation. In this study, we synthesized three π-type iridium(III) complexes and modified the C^N and N^N ligands with benzothiazole (BTZ) to regulate their light-absorption capacity and efficiency of singlet-oxygen generation. We assembled the nano-photosensitizers by wrapping them with an amphiphilic polyethylene glycol polymer with folic acid-targeting function to improve their targeting ability and biocompatibility. Modification of the BTZ group on the C^N ligand enhanced the ability of the photosensitizer to generate singlet oxygen and improved the cell uptake and PDT efficacy of the corresponding nanophotosensitizer. We believe that this type of photosensitizer provides the basis for the design of new photosensitizers based on the structure of iridium(III) complexes.

Global evaluation of the chemical hazard of recycled tire crumb rubber employed on worldwide synthetic turf football pitches

Social and environmental concern about the use of crumb rubber from end-of-life car tires in the construction of different sport and recreational facilities is increasing due to the presence of hazardous compounds. The aim of this research was the assessment of 42 organic chemicals, including polycyclic aromatic hydrocarbons (PAHs), phthalates, adipates, antioxidants and vulcanisation agents in a large number of infill samples (91) from synthetic turf football pitches of diverse characteristics and geographical origin. Samples were taken worldwide, in 17 countries on 4 continents, to show the global dimension of this problem. Ultrasound assisted extraction was employed to extract the target compounds, followed by gas chromatography coupled to tandem-mass spectrometry (UAE-GC–MS/MS). Seventy-eight crumb rubber samples as well as thirteen samples of alternatives materials, such as cork granulates, thermoplastic elastomers and coconut fibre, were analyzed. The results highlight the presence of all target PAH in most rubber samples at concentrations up to μg g−1, including the eight ECHA (European Chemicals Agency) PAHs considered as carcinogenic, and anthracene (ANC), pyrene (PYR) and benzo[ghi]perylene (B[ghi]P), catalogued as substances of very high concern (SVHC). Endocrine disruptors such as some plasticizers (mainly phthalates), and other compounds like benzothiazole (BTZ) and 2-mercaptobenzothiazole (MBTZ) were found reaching the mg g−1 level. This confirms the presence of the hazardous substances in the recycled crumb rubber samples collected all around the world. Three crumb rubber samples exceeded the limit of 20 μg g−1 for the sum of the eight ECHA PAHs. Regarding the chemical composition of other infill alternatives, cork appears to be adequate, while the thermoplastic elastomers contained high levels of some plasticizers. In addition, the plastic infill as well as the crumb rubber both are microplastics. Microplastics are considered contaminants of emerging concern since they do not biodegrade and remain in the environment for a long time.