Theoretical Study of Benzothiazole and Its Derivatives: Molecular Structure, Spectroscopic Properties, NBO, MEP and TD-DFT Analyses

Benzothiazole (BTH) and its derivatives are organic molecules with biologic actions. Because of their many applications, they are produced on a massive scale and used in a number of environmental compartments. Their discharge into water produces environmental problems, exposing our environment to public health problems. A solution that can contribute to their deterioration is becoming a necessity. For this reason, a conceptual analysis of the reactivity of benzothiazole and four of its compounds was undertaken in order to investigate certain aspects of their biodegradability. A theoretical investigations of the compounds studied were conducted in the gas and water phases with the most widely used density functional theory method, Becke-3-Parameter-Lee-Yang-Parr (B3LYP) with 6-31G+ (d, p) basis. Reactivity study calculated global indices of reactivity revealed that 2-SCH3_BTH is the most reactive. Dipole moment values analysis reveals that 2-NH2_BTH is the most soluble in water, while the lipophilicity shows that 2-NH2_BTH is the most hydrophilic compound. Thermodynamic parameters values reflect that reactions are respectively exothermic and spontaneous. By analyzing an Electrostatic Molecular Potential (EMP) map, researchers can pinpoint reactive sites on a molecule and anticipate its reactivity. This assessment is further enhanced by incorporating global and local reactivity descriptors. Additionally, an exploration of frontier molecular orbitals offers valuable insights into the molecule’s charge transfer characteristics. Moreover, a combined examination of internal and external molecular interactions unveils hyperconjugative interactions arising from charge delocalization, as elucidated through natural bond orbital (NBO) analysis.

Iron Species-Impregnated Granular Activated Carbon as Modified Particle Electrodes Applied in Benzothiazole Adsorption and Electrocatalytic Degradation

The object of this study is to prepare iron species-impregnated granular activated carbon as particle electrodes in order to improve their adsorption and electrocatalytic degradation capacity in Benzothiazole removal.The incorporation of Fe-containing catalysts was performed by Fe(NO_3)_3 impregnation.The obtained samples were characterized by BET,Fourier transform infrared spectroscopy,SEM-EDS,powder X-ray diffraction,X-ray photoelectron spectra and TG.Compared with pure activated carbon,this modified particle electrodes show higher static adsorption capacities and TOC removal,which have respectively increased by25.9% and 54.4%.Both physisorption and chemisorption exist in the process of benzothiazole adsorption,where the latter plays a major role.In this way,the Fe-containing catalysts on modified particle electrodes are demonstrated to make a greater contribution to the improvement of electrocatalytic degradation by decreasing the activated energy by 32%.

Syntheses and Mesomorphic Properties of 2-(4'-Alkoxyphenyl)-6-Substituted Benzothiazoles

Introduction Liquid crystals without a double bond bridge between two rings in the linear molecule are more stable chemically and photochemically. Alkyl cyanobiphenyl was synthesized by Richard in 1973. Later, liquid crystals with the strcture of phenylcyclohexane and cyclohexylcyclohexane also appeared. But the liquid

ZnO-beta zeolite:As an effective and eco-friendly heterogeneous catalyst for the synthesis of benzothiazole derivatives

A cheap and recyclable ZnO-beta zeolite was used as catalyst for the synthesis of benzothiazole derivatives.This method provides several advantages such as environmental friendliness,short reaction times,high yields,simple work-up procedure and catalyst was successfully reused for four cycles without significant loss of activity.

Degradation Pathway of Benzothiazole and Microbial Community Structure in Microbial Electrolysis Cells

In this study, benzothiazole was entirely mineralized by an up-flow internal circulation microbial electrolysis reactor. The bioelectrochemical system was operated at ambient temperature under continuous-flow mode. The analysis of metabolite which was extracted by HPLC-MS from the bioreactor indicated that benzothiazole derivative ( BTH ) was firstly converted into 2-hydroxybenzothiazole in the microbial electrolysis cell (MEC) and then mineralized within three steps, i.e., the fracture of thiazole-ring through a series of oxidation and hydrolysis, the deamination and hydroxylation of 2-aminobenzenesulfonic acid, and the mineralization of various carboxylic acids to CO2 and H2O. Bacterial community analysis indicated that the applied electric field could selectively enrich certain species and the dominate bacteria on the electrodes belonged to Proteobacteria, Bacteroidetes, and Firmicutes. Results show that MEC can improve the degradation efficiency of BTH in wastewater, enable the microbiological reactor to satisfy the requirements of high loading rate, thereby fulfilling the scale-up of whole process in the future.

Effect of Co-substrate on Degradation of Benzothiazole in MEC

Due to its persistence and bio-toxicity,benzothiazole(BTH) cannot be biodegraded efficiently.Recent work has shown that removal rates of biorefractory organics can be enhanced by the addition of cosubstrates.In this work,ethanol,acetate,propionate and butyrate were added as co-substrates in order to promote the degradation of BTH in microbial electrolysis cell(MEC).By probing the changes in degradation rates of BTH in the presence of different co-substrates,it was observed that all the four co-substrates can enhance the BTH degradation in MEC,both the efficiency(EBTH) and the rate(RBTH).It was also found that acetate is more effective than others,which made the degradation efficiency of BTH up to 90% with acetate-C at350 mg/L(measuring by the carbon content of co-substrate,the same below),within 6 h and the degradation rate of BTH arrived 0.001 2/(mg·h).The microbacteria in MEC have also been influenced by different cosubstrates.This metabolism of the co-substrates enables the microbacteria on anode to generate ATP and thus grow to ensure the microbacteria activity.Therefore,this work showed that the addition of co-substrates such as acetate can be a novel and efficient approach for improving the elimination of BTH from wastewaters by MEC system.

Al-Pillared Ghassoulite Clay as a New Green Catalyst for the Synthesis of Benzothiazoles and Benzimidazoles: Effect of Amine/CEC Ratio

The following article has been retracted due to the investigation of complaints received against it. The Editorial Board found that substantial portions of the text came from other published papers. The scientific community takes a very strong view on this matter, and the International Journal of Organic Chemistry treats all unethical behavior such as plagiarism seriously. This paper published in Vol.3 No.2, 151-157 (pages), 2013, has been removed from this site. Title: Al-Pillared Ghassoulite Clay as a New Green Catalyst for the Synthesis of Benzothiazoles and Benzimidazoles: Effect of Amine/CEC Ratio Authors: Rachid Azzallou,?Rachid Mamouni,?Kimberly Stieglitz,?Nabil Saffaj, Mohammadine Said

A New and Efficient Method for the Synthesis of Pyrimido[2,1-<i>b</i>]Benzothiazole Derivatives

The one-pot three-component reaction of 2-aminobenzothiazole, benzaldehyde derivatives and β-ketoester, β-diketone or malonate derivatives in solvent-free conditions provides the corresponding pyrimido [2,1-b] benzothiazole derivatives at 60?C in 60% - 72% yields without using any catalyst in an optimistic time.

Occurrence of Human Exposure to Benzothiazoles and Benzotriazoles in Indoor Dust in Suizhou and Beijing,China

Benzothiazoles(BTHs)and benzotriazoles(BTRs)are an important group of industrial chemicals.Due to large scale and long-term applications,they have been released to various environmental media,including indoor dust,and subsequently elicited a variety of toxic effects.In this study,the concentrations and composition profiles of BTHs and BTRs in indoor dust from Suizhou and Beijing,China,were investigated.The median concentrations ofΣ_(6)BTHs in indoor dust samples from Suizhou and Beijing were 133 and 439 ng/g dw,respectively,whereas theΣ5BTRs concentrations from Suizhou and Beijing were 28.4 and 40.1 ng/g dw,respectively(dw=dry weight).BTH,2-OH-BTH,1-H-BTR,and 5-Me-1-H-BTR were the predominant compounds in the dust.Human exposure to such chemicals was further evaluated.The intake for the population in Suizhou(0.163–0.939 ng/kg bw/day)and Beijing(0.0347–0.200 ng/kg bw/day)was minor(bw=body weight).The obtained results in this study will be able to add insight into human exposure to BTHs and BTRs.This study will help to identify the behavior and fate of BTHs and BTRs in the environment,and thus to scientifically assess their risk of exposure.

Robust chromophore-integrated MOFs as highly visible-white-light active and tunable size-selective photocatalysts towards benzothiazoles

Visible-light heterogeneous photocatalyst with high activity and selectivity is crucial for the development of organic transformations, but remains a formidable challenge. Herein, a simple and effective strategy was developed to integrate tetrazine moiety, a visible light active unit, into robust metal-organic frameworks(2D MOF-1(M), M = Co, Mn, Zn, and 3D MOF-2(Co)). MOF-1 series are isomorphous 2D porous frameworks, and MOF-2(Co) displays 3D porous framework. Interestingly, benefiting from the oxidative active species of O_(2)·-, these MOFs all exhibit obviously highly enhanced photocatalytic activities toward the straightforward condensation of o-aminothiophenol and aromatic aldehydes at room temperature in Et OH under visible-white-light irradiation. Notably, compared to 3D MOF, the 2D layered MOF-1(Co) exhibited more excellent catalytic activity with a wide range of substrates possessing preeminent tolerance of steric hindrance. Most impressively, MOF-1(Co) can be recycled at least five times without significant loss of catalytic activity or crystallinity, exhibiting excellent stability and reusability. This study sheds light on the wide-ranging prospects of visible light active 2D MOFs as green photocatalysts for the preparation of fine chemicals.

Gamma irradiation of 2-mercaptobenzothiazole aqueous solution in the presence of persulfate

Recently, water treatment by ionizing radiation has gained increasing attention as a powerful technology for the destruction of refractory pollutants. 2-Mercaptobenzothiazole(MBT) is known as a widespread, toxic and poorly biodegradable pollutant. This paper studied the gamma irradiation of aqueous solutions of MBT. Moreover, the effect of the addition of persulfate(S2O82-) on the radiolytic destruction of MBT was investigated. The main transformation products of the studied compound were detected and the sequence of occurrence of the products was described. The change of biodegradability of MBT solution was also observed. The main results obtained in this study indicated that gamma radiation was effective for removing MBT in aqueous solution. Persulfate addition, which induced the formation of reactive sulfate radicals(SO4-U), greatly enhanced the degradation of MBT. Benzothiazole was identified as the first radiation product, followed by 2-hydroxybenzothiazole. Decomposition of MBT started with the oxidation of –SH groups to sulfate ions. Possible pathways for MBT decomposition by gamma irradiation were proposed. The BOD/COD ratios of MBT samples were increased after radiation,indicating the improvement of biodegradability and reduction of toxicity.

Comparison of benzothiazole-based dyes for sensitive DNA detection

For efficient and quantitative DNA detection,fluorescence staining is the most often explored approach,which relies on non-covalent binding of dyes with double stranded DNA(dsDNA).Ethidium bromide(EB)is the most classic DNA stain,but suffers from its high carcinogenicity.A series of less toxic alternatives were developed,many of which contain the core structure of the benzothiazole ring.However,the relationship between the structure and the DNA detection performance was not illustrated.Herein,five benzothiazole dyes,namely thiazole orange,SYBR Green I,Pico Green,SYBR Safe,and thioflavine-T,were compared for DNA detection through direct fluorescence and gel electrophoresis,with particular focus on the structure-performance relationship.It turned out that SYBR Green I is currently the best choice for DNA detection.The results in this work may be useful for future DNA-staining dye developments.

A ratiometric benzothiazole-based fluorescence probe for selectively recognizing HClO and its practical applications

A ratiometric probe(HBT-HBZ)bearing 2-hydrazino benzothiazole and 3-(benzo[d]thiazol-2-yl)-2-hydroxy-5-methylbenzaldehyde for sensing hypochlorous acid(HClO)with high selectivity and sensitivity is reported in this article.The fluorescence intensity ratios(I470nm/I572nm)of the probe with different concentrations of analyte showed excellent selectivity and a linear response to minor changes in HClO.The detection limit of 24 nmol/L suggests that the sensor is very sensitive to HClO.According to the series of performed experiments,HBT-HBZ has practical applications,such as the detection of HClO residues in tap water,which has been rarely reported.In addition,confocal laser microscopy experiments confirmed that HBT-HBZ can selectively recognize HClO in HeLa cells.A ratiometric probe(HBT-HBZ)for sensing HClO with high selectivity and sensitivity is reported in this article.The probe exhibited high selectivity for HClO among other ROS,RNS and anions.In addition,HBTHBZ has some practical applications such as the analysis of the HClO content in tap water.Furthermore,confocal fluorescence microscopy imaging showed that HBT-HBZ can be applied for detecting HClO in living cells.

A QSAR study and molecular design of benzothiazole derivatives as potent anticancer agents

A quantitative structure-activity relationship (QSAR) of a series of benzothiazole derivatives showing a potent and selective cytotoxicity against a tumorigenic cell line has been studied by using the density functional theory (DFT), molecular mechanics (MM+) and statistical methods, and the QSAR equation was established via a correlation analysis and a stepwise regression analysis. A new scheme determining outliers by "leave-one-out" (LOO) cross-validation coefficient (q2n-i) was suggested and successfully used. In the established optimal equation (excluding two outliers), the steric parameter (MRR) and the net charge (QFR) of the first atom of the substituent (R), as well as the square of hydrophobic parameter (lgP)2 of the whole molecule, are the main independent factors contributing to the anticancer activities of the compounds. The fitting correlation coefficient (R2) and the cross-validation coefficient (q2) values are 0.883 and 0.797, respectively. It indicates that this model has a significantly statistical quality and an excellent prediction ability. Based on the QSAR studies, 4 new compounds with high predicted anticancer activities have been theoretically designed and they are expected to be confirmed experimentally.

Sedimentary environment indicators: Benzothiazole and its derivatives

Benzothiazoles distributional characteristics of crude oils and non-hydrocarbon fractions of source rocks in Mangya depression of the Qaidam Basin, Lunnan oil field in the Tarim Basin, Kelamayi oil field in the Junggar Basin and the Tulufan Basin oil field were analyzed. It was found that the distributions of benzothiazole are remarkable diversity in different sedimentary environmental oils. The swamp crude oils contain high quantity of benzothiazole and relatively high quantity of alkylthio-benzothiazole and 2(3H)-benzothiazolone. But the quantity of the 2,2’-dithiobis-benzothiazole is relatively low. The abundance of benzothiazole and 2,2’-dithiobis-benzothiazole are relatively high insemi-brackish water lacustrine crude oils, but the quantity of alkylthio-benzothiazole and 2(3H)-benzothiazolone are relatively low. The benzothiazoles belong to weak acid and mild base compound, and their stabilization conditions relate to their environmental medium. The nitrogenous bases are in favor of alkalescence

Iodine-catalyzed amination of benzothiazoles with KSeCN in water to access primary 2-aminobenzothiazoles

A facile and sustainable approach for the amination of benzothiazoles with KSe CN using iodine as the catalyst in water has been disclosed under transition-metal free conditions. The reaction proceeded smoothly to afford various primary 2-amino benzothiazoles in up to 96% yield. A series of control experiments were performed, suggesting a ring-opening mechanism was involved via a radical process. This protocol provides efficient synthesis of primary 2-aminobenzothiazoles.

Syntheses, Crystal Structures and DNA-binding Properties of Zn(Ⅱ), Ni(Ⅱ) and Co(Ⅱ) Compounds Containing Thiazole Derivatives

Zn(Ⅱ), Ni(Ⅱ) and Co(Ⅱ) compounds(1～3) based on 2-(2-pyridyl)benzothiazole(bpt) and terephthalic acid(PTA) were synthesized. The crystal structures of [Zn(bpt)(PTA)2](1), [Ni(bpt)(PTA)2](2), and [Co(bpt)(PTA)2](3) have been determined by single-crystal X-ray diffraction analysis, which shows that all the three complexes belong to monoclinic system with space group P21/c. Time-dependent density functional theory(TD-DFT) calculation is performed on a reference structure of compound 3. The excited electrons mainly localized at the π* of ligand 2-(2-pyridyl)benzothiazole, which will be convenient for them to bind with the DNA reacting sites. Fluorescence spectroscopy, ultraviolet(UV) spectroscopy and viscosity were used to characterize the interaction of the compounds with Calf thymus DNA(CT-DNA). The results indicate that compounds 1～3 bind to CT-DNA and have a strong interaction with DNA. The compounds can probably bind to CT-DNA via a non-intercalative mode as concluded by studying the viscosity of a DNA solution in the presence of the compounds. This combination can effectively break DNA, which speculates that these three compounds may interact with the cancer cell DNA in this binding mode, thereby damaging the cancer cells.

Influence of intramolecular hydrogen bond formation sites on fluorescence mechanism

The fluorescence mechanism of HBT-HBZ is investigated in this work. A fluorescent probe is used to detect HClO content in living cells and tap water, and its structure after oxidation by HCl O(HBT-ClO) is discussed based on the density functional theory(DFT) and time-dependent density functional theory(TDDFT). At the same time, the influence of the probe conformation and the proton transfer site within the excited state molecule on the fluorescence mechanism are revealed. Combined with infrared vibrational spectra and atoms-in-molecules theory, the strength of intramolecular hydrogen bonds in HBT-HBZ and HBT-ClO and their isomers are demonstrated qualitatively. The relationship between the strength of intramolecular hydrogen bonds and dipole moments is discussed. The potential energy curves demonstrate the feasibility of intramolecular proton transfer. The weak fluorescence phenomenon of HBT-HBZ in solution is quantitatively explained by analyzing the frontier molecular orbital and hole electron caused by charge separation. Moreover, when strong cyan fluorescence occurs in solution, the corresponding molecular structure should be HBT-ClO(T). The influence of the intramolecular hydrogen bond formation site on the molecule as a whole is also investigated by electrostatic potential analysis.

Chemical Conversion of a Coumarin Derivative Containing Arylhydrazono: Crystal Structures and Fluorescence Properties

An arylhydrazono-containing coumarin derivative(1) can undergo chemical conversions in two modes. When in the presence of Cu^(2+), a Cu^(2+)-promoted cyclization reaction was observed in aqueous acetonitrile and gives compound 2, while a ring-opening reaction occurs to give compound 3 in the absence of Cu^(2+). Both 2 and 3 were characterized by single-crystal X-ray diffraction. Compound 2 crystallizes in monoclinic C2/c space group with a = 26.606(5), b = 5.8142(12), c = 26.906(5) ?, β = 103.41(3)°, Z = 8, F(000) = 1696, μ = 0.186 mm^(-1), R = 0.0487 and wR = 0.1129. Compound 3 crystallizes in monoclinic P21/n space group with a = 9.917(2), b = 13.644(3), c = 15.912(3) ?, β = 95.38(3)°, Z = 4, F(000) = 896, μ = 0.182 mm^(-1), R = 0.0769 and w R = 0.1617. The spectroscopic studies show that compound 2 exhibits strong fluorescence emission.