- UV-induced transformations of matrix-isolated 1,3,4-thiadiazole-2-thiones
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Monomers of 5-mercapto-1,3,4-thiadiazole-2-thione (bismuthiol) were studied using an experimental matrix-isolation technique as well as by carrying out theoretical quantum chemical calculations. The calculations, performed using the quadratic configuration interaction method with single and double excitations (QCISD)/6-31++G(d,p)//DFT(B3LYP)/ 6-311 ++G(2d,p), predict that the thione-thiol tautomer of bismuthiol should be significantly (by more than 19 kJ mol-1) more stable than other tautomeric forms. Accordingly, only the signatures of the thione-thiol tautomer were observed in the FT-IR spectrum of bismuthiol, recorded directly after deposition of an Ar matrix. UV (l> 320 nm) irradiation induced the conversion of the thione-thiol tautomer into the dithiol form. Analogous investigations were carried out for two related compounds: 5-methyl-1,3,4-thiadiazole-2-thione and 5-methylthio-1,3,4-thiadiazole-2-thione. For these two species, only the thione tautomeric forms were observed after deposition of Ar matrices. These tautomers were predicted (by QCISD calculations) to be more stable (by at least 19kJmol-1) than other tautomeric forms. Upon UV irradiation, the most stable thione forms of these compounds were transformed into the corresponding thiol tautomers. Direct observation of the thione! thiol phototautomeric processes provides a clear proof that intramolecular proton transfer reaction can occur in molecules, such as bismuthiol, in spite of the increased NH...S distance, in comparison to other phototautomerizing species studied so far. All the isomers of the studied compounds (substrates and products of the photoreactions) were identified by comparison of their IR spectra with the spectra calculated at the DFT(B3LYP)/6-311 ++G(2d,p) level of theory for possible isomeric structures. Copyright
- Rostkowska, Hanna,Lapinski, Leszek,Nowak, Maciej J.
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- Synthesis, characterization and antibacterial evaluation of some novel benzimidazole derivatives containing 1,3,4-thiadiazole moiety
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A series of novel 5-amino-1,3,4-thiadiazole-2-thiol and 1,3,4-thiadiazole-2,5-dithiol derivatives of benzimidazole were synthesized through nucleophilic substitution reaction of 5-substituted-2-(chloromethyl)-1H-benzimidazole, structures of the synthesized compounds were proved by spectral methods of analysis (FT-IR, 1H and 13C NMR). All the target compounds were screened for their antibacterial activity toward gram-negative (E.coli, P. aeruginosa) and Gram-positive (B. subtilis, S. aureus) bacteria, most of the synthesized derivatives exhibited good to moderate activity toward both Gram-positive (B. subtilis, S. aureus) and Gram-negative (E.coli, P. aeruginosa) bacteria.
- Redayan, Muayed Ahmed,Ali, Wassan Baqir,Mohammed, Ahmed Mudhafar
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- Copper(I) Chloride π-Complexes with 2,5-Bis(Allylthio)-1,3,4-Thiadiazole: Synthesis and Structural Features
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Three new Cu(I) π-complexes with 2,5-bis(allylthio)-1,3,4-thiadizole (Bialtia) ([Cu3Cl3(Bialtia)2] (1), [Cu3Cl3(Bialtia)] (2), and [Cu2Cl2(Bialtia)] (3)) are obtained by the alternating current electrochemical synthesis and studied by single crystal X-ray diffraction. A distinctive feature of Bialtia is its ability to coordinate to Cu(I) atoms by nitrogen atoms of the thiadiazole core and two allyl groups. The formation of island inorganic {Cu3Cl3} moieties occurs in 1 through π coordination of two independent Bialtia molecules by three metal atoms. Due to the absence of one Bialtia molecule in 2, inorganic {–Cu3Cl3–} subunits join into infinite chains {[Cu3Cl3(Bialtia)]}n}. The structure of [Cu2Cl2(Bialtia)] (3) contains two Cu(I) atoms with different coordination environments: distorted tetrahedral and trigonal.
- Slyvka, Yu. I.,Ardan,Mys’kiv
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- Synthesis of novel 2,5-disubstituted-1,3,4-thiadiazoles clubbed 1,2,4-Triazole, 1,3,4-Thiadiazole, 1,3,4-Oxadiazole and/or schiff base as potential antimicrobial and antiproliferative agents
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In the present study, a new series of 2,5-disubstituted-1,3,4-thiadiazole tethered 1,2,4-triazole, 1,3,4-thiadiazole, 1,3,4-oxadiazole and Schiff base derivatives were synthesized and characterized by IR, 1H-NMR, 13C-NMR, MS and elemental analyses. All compounds were screened for their antibacterial, antifungal and antiproliferative activity. Some of the synthesized derivatives have displayed promising biological activity.
- Rezki, Nadjet,Al-Yahyawi, Amjad M.,Bardaweel, Sanaa K.,Al-Blewi, Fawzia F.,Aouad, Mohamed R.
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- Synthesis of novel 2,5-bis(substituted thio)-1,3,4-thiadiazoles by acid catalyzed intermolecular cyclization reactions of substituted dithiocarbazates as a possible 2019-nCoV main protease inhibitor
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A convenient and facile synthesis of a privileged pharmaceutical scaffolds, 2,5-bis(substituted thio)-1,3,4-thiadiazoles is accomplished. The reaction of hydrazine hydrate with carbon disulfide and substituted alkyl/aryl chloride in basic medium yielded S-substituted alkyl/aryl dithiocarbazates in high yield. These dithiocarbazates on reaction with tetrafluoro acetic acid underwent a unique acid catalyzed intermolecular cyclization reaction to afford a novel 2,5-bis(substituted thio)-1,3,4-thiadiazoles. A simple procedure and high yields are the characteristic features of these reactions. These compounds are characterized on the basis of physico-chemical and spectral (FT-IR, ESI Mass, 1H, 13C and DEPT 135° 13C {1H} NMR) studies. Compound 2b crystallizes in orthorhombic system with point group P bca. Using the DFT/B3LYP/6–311 G (d,p) level of theory, HOMO-LUMO energy gap and molecular electrostatic potential (MEP) analyses were carried out. The HOMO-LUMO energy gap allowed the calculation of chemical hardness, chemical inertness, electronegativity and the electrophilicity index of the molecule, which depicted their potential kinetic stability and reactivity. The molecular docking studies of 2b-2e with 2019-nCoV main protease(7BRO) revealed binding free energies of (ΔGb) = -6.22, -5.38, -4.43 and -4.25 kcal mol?1 respectively. Docking study revealed that the aromatic congeners exhibit appreciable therapeutic efficiency to be used as 2019-nCoV main protease inhibitors.
- Bhat, Muzzaffar A.,Butcher, Ray J,Jan, Misba,Jasinski, Jerry P.,Manzoor, Unjum,Shalla, Aabid H.
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- Synthesis and Characterization of New Ligand N,N-Dimethyl-4-[(E)-(2-{5-[2-(5-phenyl-1,3,4-oxadiazol-2-yl)hydrazinyl]-1,3,4-thiadiazol-2-cyl}hydrazinylidene) methyl]aniline and Transition Metal Complexes
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A new ligand N,N-dimethyl-4-((2-(5-(2-(5-phenyl-1,3,4-oxadiazole-2-yl)hydrazinyl)-1,3,4-thiadiazol-2-yl)hydrazono)methyl)aniline and its Cr(III),Ni(II) and Co(II) complexes were synthesized, and characterized by FTIR, 1H-NMR, and mass spectral data. The ligand acts as bidentate ligand coordinating through the nitrogen atom. The program of hyperchem 8 has been used for theoretical accounts using PM3 method to study the electrostatic potential that provided good information to determine the appropriate positioning complexity. Based on the spectral data, the octahedral geometry for the Cr(III), tetrahedral geometry for Co(II), and square planar geometry for Ni (II) have been suggested.
- Nasir, Ali.F.,Flifl, Ibrahim A.
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p. 453 - 457
(2021/02/02)
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- Synthetic method of 2,5-dimercapto-1,3,4,-thiadiazole
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The invention discloses a synthetic method of 2,5-dimercapto-1,3,4,-thiadiazole and mainly relates to the technical field of synthesis of fine chemicals. The synthetic method comprises the following steps: adding ethanol, a hydrazine hydrate, carbon disulfide and a solid base catalyst into a reaction vessel, stirring at a temperature of 20-100 DEG C to react for 1-10 hours, then cooling to room temperature, filtering, distilling filtrate under reduced pressure to remove a solvent to obtain a yellowish solid, and re-crystallizing with absolute ethyl alcohol to obtain a product DMTD. The synthetic method disclosed by the invention has the benefits that the solid base catalyst is adopted for catalysis, so that the problems that a traditional strong base catalyst corrodes equipment, and the product post-treatment is difficult are solved; the catalyst can be recycled and has the advantages of being mild in reaction conditions, low in production cost, low in equipment corrosion, easy in product separation, high in catalytic activity, low in environment pollution and the like; the synthetic method is a green synthetic technique.
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Paragraph 0028-0039
(2019/07/04)
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- Thiadiazole bactericide and preparation method and application thereof
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A thiadiazole bactericide comprises 2,5-dimercapto-1,3,4-thiadiazole and/or 2,5-dimercapto-1,3,4-thiadiazole metal complex; the 2,5-dimercapto-1,3,4-thiadiazole metal complex has a structural generalformula which is shown in the description, wherein R is metal cation. Compared with the prior art, the thiadiazole bactericide according to the invention has the advantages that the production cost islow, production materials are easy to attain, the production process is mature and simple, the yield is high, the activity is high, and the thiadiazole bactericide has better effect in eliminating bacterial and fungal diseases of plants and causes less damage.
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Paragraph 0011; 0012
(2019/03/08)
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- Convenient Synthesis and Biological Activity of Mono and Diacyl 2,5-Dimercapto-1,3,4-thiadiazole Derivatives
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New derivatives of 2,5-dimercapto-1,3,4-thiadiazole substituted both at one or two exocyclic sulfur atoms with a series of aroyl or ethoxycarbonyl groups were synthesized in reactions of 2,5-dimercapto-1,3,4-thiadiazole salts with appropriate acid chlorides or ethyl chloroformate in mild conditions. The products were characterized by spectroscopy (1H NMR, 13C NMR, IR, and HRMS). Some from the synthesized compounds were screened in vitro and in vivo for antibacterial and antifungal activities against a panel of reference strains of microorganisms. The study revealed that ethyl S-(5-mercapto-1,3,4-thiadiazol-2-yl) carbonothioate seems to be the most active and versatile compound against Gram-positive bacteria, Gram-negative bacteria, and plant pathogenic fungi.
- Jasiak, Karolina,Kudelko, Agnieszka,Wróblowska, Monika,Biernasiuk, Anna,Malm, Anna,Krawczyk, Maria
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p. 3241 - 3249
(2017/10/06)
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- Oxadiazoles and thiadiazoles: Novel α-glucosidase inhibitors
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Oxadiazoles and thiadiazoles 1-37 were synthesized and evaluated for the first time for their α-glucosidase inhibitory activities. As a result, fifteen of them 1, 4, 5, 7, 8, 13, 17, 23, 25, 30, 32, 33, 35, 36 and 37 were identified as potent inhibitors of the enzyme. Kinetic studies of the most active compounds (oxadiazoles 1, 23 and 25, and thiadiazoles 35 and 37) were carried out to determine their mode of inhibition and dissociation constants Ki. The most potent compound of the oxadiazole series (compound 23) was found to be a non-competitive inhibitor (Ki= 4.36 ± 0.017 μM), while most potent thiadiazole 35 was identified as a competitive inhibitor (Ki= 6.0 ± 0.059 μM). The selectivity and toxicity of these compounds were also studied by evaluating their potential against other enzymes, such as carbonic anhydrase-II and phosphodiesterase-I. Cytotoxicity was evaluated against rat fibroblast 3T3 cell line. Interestingly, these compounds were found to be inactive against other enzymes, exhibiting their selectivity towards α-glucosidase. Inhibition of α-glucosidase is an effective strategy for controlling post-prandial hyperglycemia in diabetic patients. α-Glucosidase inhibitors can also be used as anti-obesity and anti-viral drugs. Our study identifies two novel series of potent α-glucosidase inhibitors for further investigation.
- Kashtoh, Hamdy,Hussain, Shafqat,Khan, Ajmal,Saad, Syed Muhammad,Khan, Jalaluddin A.J.,Khan, Khalid Mohammed,Perveen, Shahnaz,Choudhary, M. Iqbal
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p. 5454 - 5465
(2015/02/02)
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- Process for the Preparation of Bis-DMTD
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The present invention relates to a process for the preparation of bis(dimercaptothiadiazole) (or bis-DMTD), more particularly of 5,5′-dithiobis(1,3,4-thiadiazole-2-thiol), said process being carried out in a single reactor and making possible a preparation with improved yields which is more respectful of the environment.
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Page/Page column 4
(2011/01/12)
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- Unusual rearrangement in reactions of propanodihydrazide and butanodihydrazide with carbon disulfide
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An unexpected reaction of propanodihydrazide and butanodihydrazide with carbon disulfide giving 2,5-dimercapto-1,3,4-thiadiazole has been observed. A possible mechanism for this unusual rearrangement is given.
- Al-Talib, Mahmoud,Tashtoush, Hasan
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p. 1374 - 1376
(2007/10/03)
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- Dipolar cycloaddition reactions of nitrilimines
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A series of γ-substituted α-methylidene-γ-butyrolactone derivatives underwent regiospecific 1,3-dipolar cycloaddition with N-methyl-C-phenylnitrilimine. These reactions proceeded regiospecifically and with high diastereoselectivity, generally favouring the anti diastereomer as determined by n.m.r, spectroscopy and semiempirical molecular orbital calculations. The assignment for one product was confirmed by X-ray crystallography. N-Methyl- C-phenylnitrilimine underwent regiospecific cycloaddition with a range of C=S-containing dipolarophiles. Substituted thioureas were generally unreactive as dipolarophiles, while 5-thio-substituted 1,3,4-thiadiazole-2(3H)-thiones underwent ready reaction to produce, rather than the expected cycloadducts, complex rearrangement products. The structure of one of these unusual products has been confirmed by X-ray crystallography. A series of disubstituted nitrilimines underwent regiospecific cycloaddition with thiobenzophenone; the structures of the products were confirmed by X-ray crystallography.
- Dunstan, James B. F.,Elsey, Gordon M.,Russell, Richard A.,Paul Savage,Simpson, Gregory W.,Tiekink, Edward R. T.
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p. 499 - 509
(2007/10/03)
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