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.

A simple and efficient synthesis of 2-substituted benzothiazoles catalyzed by H_2O_2/HCl

A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H2O2/HCl system in ethanol at room temperature is described. The target compounds have been characterized by ^1H NMR, ^13C NMR, IR and MS. Short reaction time, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.

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%.

Synthesis and mesomorphic behavior of benzothiazole-based liquid crystals having terminal methoxyl group

A homologous series of benzothiazole derivatives, 6-methoxy-2-（4-alkanoyloxybenzylidenamino）benzothiazoles, were synthesized and characterized using FT-IR, ^1H and ^13C NMR, mass spectrometry and elemental analysis. Enantiotropic nematic phase was observed throughout the entire series. Smectic C phase only emerged from the decanoyloxy derivative onwards. The terminal methoxyl group and the ester linkage influenced the mesomorphic behavior of the present series.

Synthesis,Crystal Structure and Antimicrobial Activity of a New Ternary Copper(Ⅱ) Complex with p-Chlorophenoxyacetic Acid and 2-Amino Benzothiazole

A novel ternary complex of Cu（pcpa）2（aben）2 （pcpa=p-chlorophenoxyacetic acid anion,aben=2-amino benzothiazole） was synthesized by the reaction of copper acetate,2-amino benzothiazole and p-chlorophenoxyacetic acid.Elemental analysis,IR,UV and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure.The crystal crystalli-zes in the monoclinic system,space group C2/c with a=25.795（4）,b=7.384（3）,c =17.741（6）,β=107.47（2）°,C30H24Cl2CuN4O6S2,Mr=735.09,V=3223.2（18） 3,Z=4,Dc=1.515 Mg/m3,λ（MoKα）=0.71073 ,μ=1.022 mm-1,F（000）=1500,the final R=0.0464 and wR=0.1244.A total of 3218 unique reflections were collected,of which 2228 with I 〉 2σ（I） were observed.The Cu（II） atom is four-coordinated with two carboxylate oxygen atoms of the two pcpa ligands and two nitrogen atoms in thiazole rings of two aben ligands.The analysis of crystal structure shows intermolecular and intramolecular hydrogen bonds between amino-nitrogen atoms of the two aben ligands and carboxylate oxygen atoms of the two pcpa ligands.The antimicrobial properties of the title complex and its two free ligands were tested against representative bacterial and fungal strains.Results show that the antibacterial activity of the complex is less than or equal to that of 2-amino benzothiazole,but for yeasts and moulds,it exhibits excellent inhibitory effect better than that of its two free ligands.

Synthesis and Characterization of a New Ligand 2-(4, 5-Dihydro-2-thiazolyl)-6-methoxylbenzothiazole and Its Dinuclear Co(II) Complex

A new ligand 2-（4,5-dihydro-2-thiazolyl）-6-methoxyl benzothiazole and its new dinuclear Co（II） coordination complex [Co（C11H10N2OS2）Cl2]2·2CHCl3 （1） have been synthesized and characterized. Complex 1 was synthesized by the reaction of Co（II） salt with 2-（4,5-dihydro- 2-thiazolyl）-6-methoxyl benzothiazole under room-temperature evaporation condition and struc- turally characterized by single-crystal X-ray diffraction analysis and IR spectroscopy. The supramolecular network of complex 1 is stabilized by the presence of intermolecular interaction, such as C-H···Cl hydrogen bonding and π-π stacking. The complex crystallizes in triclinic, space group P1 with a = 8.3288（12）, b = 10.5273（15）, c = 10.822（2）, α = 93.416（3）, β = 90.864（3）, γ = 94.890（3）o, V = 943.60（2）3, Z = 2, Dc = 1.758 g/cm3, F（000） = 498 and μ = 1.840 mm-1. The final complex [Co（C11H10N2OS2）Cl2]2·2CHCl3 is a diplex bridged dinuclear complex consisting of two Co（II） ions, two ligands, two bridging Cl- anions and two terminal Cl- anions.

Synthesis,Crystal Structure and Recognition Properties of a New Benzothiazole Derivative：C28H24N4O2S

A benzothiazole-based compound 1, C28H24N4O2S, has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 9.6309（14）, b = 15.230（2）, c = 17.197（3）A, β = 105.222（2）°, V = 2433.9（6） A^3, Z = 4, F（000） = 1008, Dc = 1.311 Mg/m^3, Mr = 480.57, μ = 0.166 mm^-1, the final R = 0.0509 and wR = 0.1481 for 6643 observed reflections with I 〉 2σ（I）. The crystal structure of compound 1 is stabilized by C–H…O, N–H…N, N–H…O, O–H…N and C–H…N hydrogen bonds. The spectroscopic studies of the title compound toward various metal ions were also investigated in 25%（V/V） ethanol aqueous solution, and the result showed that it can selectively recognize Cu^2＋ with fluorescence quenching.

Crystal Structures of 2-Aminobenzothiazole-based Inhibitors in Complexes with Urokinase-type Plasminogen Activator

Urokinase-type plasminogen activator （uPA） plays a crucial role in the regulation of plasminogen activation, tumor cell adhesion and migration. The inhibition of uPA activity is a promising mechanism for anti-cancer therapy. Most current uPA inhibitors employ a highly basic group （either amidine or guanidine group） to target the S1 pocket of uPA active site, which leads to poor oral bioavailability. Here we study the possibility of using less basic 2-aminobenzothiazole （ABT） as S1 pocket binding group. We report the crystal structures of uPA complexes with ABT or 2-amino-benzothiazole-6-carboxylic acid ethyl ester （ABTCE）. The inhibitory constants of these two inhibitors were measured by a chromogenic competitive assay, and it was found that ABTCE is a better inhibitor for uPA （Ki = 656 μM） than ABT （Ki = 5.03 mM）. This work shows that 2-amniobenzothiazole can be used as P1 group which may have better oral bioavailability than the commonly used amidine or guanidine group. We also found the ethyl ester group occupies the characteristic oxyanion hole and contacts to uPA 37- and 60-loops. Such work provides structural information for further improvements of potency and selectivity of this new class of uPA inhibitor.

New mesogenic Schiff base esters comprising benzothiazole moiety:Synthesis and mesomorphic properties

A homologous series of Schiff base esters, 6-methoxy-2-（2-hydroxy-4-alkanoyloxybenzylidenamino）benzothiazoles, compris- ing a benzothiazole moiety as the core was synthesized. All the members of this series exhibited an enantiotropic nematic phase. The azomethine linkage along with the lateral hydroxyl and terminal methoxyl groups were found to exert an effect on the mesomorphic properties. 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

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.

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 crystals

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.

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.

Convenient Solid-phase Synthesis of Benzothiazole Derivatives

Resin-bound cyclic malonic ester l reacted with aryl isothiocynate, then was treated with bromine, followed by cleavage from the resin under perchloric acid to give benzothiazoles 4.

Single & Two-photon Excited Fluorescence of Two New Compounds with 2-Benzothiazolyl as Electron Acceptor

Two new D--A type compounds, where electron-donor D is tertiary amino group, electron-acceptor A is 2-benzothiazolyl and ?is two conjugated styryl units, have been synthesized. They are named as trans, trans-2-{4-[4-(N, N-diethylamino)styryl]styryl}-1, 3-benzothiazole and trans, trans-2-{4-[4-(N, N-diphenylamino)styryl]styryl}-1, 3-benzothiazole. Both compounds show strong two-photon excited fluorescence in yellow-orange region when excited by a femtosecond laser at 800 nm.

SYNTHESIS OF 2-(4'-ALKOXYPHENYL)-6-SUBSTITUTED BENZOTHIAZOLES AND THEIR LIQUID CRYSTAL CHARACTERS

A series of 2-(4'-alkoxyphenyl)-6-substituted henzothiazoles are synthesized in this paper.They are confirmed to be liquid crystals.

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

Synthesis, Spectroscopy and X-Ray Characterization, of Novel Derivatives of Substituted 2-(Benzothiazol-2’-ylthio)acetohydrazide

Treatment of 2-(benzo[d]thiazol-2’-ylthio)acetohydrazide (3) with acetylacetone afforded N-(4-oxopentan-2-ylidine) acetohydrazide derivative 5. The acetohyrazide derivatives 3 and 5 were utilized as a key intermediate for the synthesis of a novel heterocyclic compounds. The synthesis of a novel series of condensation and substituted derivatives of 2-(benzo[d]thiazol-2’-ylthio) acetohydrazide in good yield has been reported. The newly synthesized compounds were characterized by elemental analysis 1H-NMR, 13C-NMR spectra and X-ray crystallographic investigations. The reported crystal structures of these novel 2-(benzo[d] thiazol-2’-ylthio)acetohydrazide derivatives are expected to be a remarkable contribution to the crystallographic database of heterocyclic compounds.

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.