Phase Transfer Catalyzed Synthesis and Antibacterial Activity of Water-soluble S-Triazolo[3,4-b][1,3,4]thiadiazoles Containing Piperazine Group

6/3-（4-Chlorophenyl）-s-triazolo[3, 4-b][1, 3, 4]thiadiazoles （2,a-e） and （Sa-e） were synthesized respectively by intermolecular cyclization of 5-aryl / 4-chlorophenyl-4-amino-3- mercapto-1, 2, 4-triazoles （la-e） and （4） with 4-chlorobenzoic acid / aryl acids, which were condensed with piperazine under phase transfer catalyst TBAB to yield the corresponding free bases of monopiperazine derivatives and followed to form water-soluble salts （3a-e） and （6a-e） with hydrochloric acid in good yields. The in vitro biological results showed that piperazine group conjugated with the above fused heterocycles played an important role in antibacterial activity. The structures of novel compounds were confirmed by IR, ＇H NMR, MS and elemental analysis.

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF 3,6-DISUBSTITUTED S-TRIAZOLO[3,4-b]-1,3,4-THIADIAZOLES

A series of 3,6-disubstituted s-triazolo[3,4-b]-1,3,4-thiadiazoles have been synthesized,whose structures were determined by elemental and spectral analyses;all the new compounds showed significant antibacterial activity.

Synthesis, Crystal Structure and Fungicidal Activity of 3-(4-Chloro-3-ethyl-1-methyl-1H-pyrazol-5-yl)-6-(E)phenylvinyltriazolo[3,4-b]-1,3,4-thiadiazole

The crystal structure of the title compound 3 (4 Chloro 3 ethyl 1 methyl 1H pyrazol 5 yl) 6 (E)phenylvinyltriazolo[3,4 b] 1,3,4 thiadiazole (C 17 H 15 ClN 6S, M r =370.87) was determined by single crystal X ray diffraction. The crystal is monoclinic, space group P2 1/n , a=10.862(2), b=11.541(2), c=14\^994(3), β=108.41(3)°, V=1783(1), Z=4, D x =1.381 g/cm -3 , μ =0.3361 mm -1 , and F (000)=768. The results confirmed that the title compound belongs to type E of stereochemistry. The dihedral angle between triazole and 1,3,4 thiadiaole ring is 3° and the torsion angle between 1,3,4 thiadiazole and pyrazole ring is 134.0°.

Synthesis and Crystal Structure of a New Coordination Polymer:{[AgL]ClO_4}_n (L=2,5-Bis(3-pyridinylmethylthio)-1,3,4-thiadiazole)

The title complex {[AgL]ClO4}n（L=2,5-bis（3-pyridinylmethylthio）-1,3,4-thiadiazole） was synthesized by the reaction of Ag（I） salt and a novel flexible ligand L.Its structure was determined by X-ray crystallography with the following data：monoclinic,space group P21/n,a=16.5068（13）,b=7.6548（4）,c=16.5521（13）A,β=115.119（3）o,V=1893.7（2）A^3,Z=4,Dc=1.893 g/cm^3,μ=1.565 mm^-1,F（000）=1072,C14H12AgClN4O4S3,Mr=539.78,T=293（2） K,S=1.067,the final R=0.0342 and wR=0.0870.The silver ion in the complex is in a trigonal coordination geometry to link three different L.Meanwhile,each L connects three different silver ions by its N coordination sites to form a two-dimensional layer structure.

Synthesis and Crystal Structure of 3-(4-Ethoxyphenyl)-6-(phenoxymethyl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole

The title compound C18H16N4O2S has been synthesized by the reaction of 4-amino-3-（4-ethoxyphenyl）-5-mercapto-1,2,4-triazole with phenoxyacetic acid in phospho- rus oxychloride, and characterized by IR, NMR spectra and elemental analysis. Its structure was determined by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 1.4903（3）, b = 1.5230（2）, c = 0.9615（16） nm, Z = 4, V = 1.7769（5） nm^3, Dc = 1.317 g/cm^3, μ = 0.201 mm^-1, F（000） = 736, R = 0.0795 and wR = 0.2233. In the title compound, all rings are essentially planar.

Synthesis and Crystal Structure of 2,3,4,6-Tetra-O-acetyl-1-{2-[(4-nitrophenoxy)methyl]-1,3,4-thiadiazole-5-thione-4-yl}-1-deoxy-β-D-glucopyranose

The title compound has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction.The crystal is of orthorhombic system （C23H25N3O12S2,Mr=599.58）,space group P212121 with a=6.2102（12）,b=17.803（4）,c=24.223（5）,V=2678.0（9）3,Z=4,Dc=1.487 g/cm3,F（000）=1248,μ=0.268 mm-1,the final R=0.0483 and wR=0.1108 for 4174 observed reflections （I 〉 2σ（I））.The C=S bond,which parallels to the anomeric C-H,adopts α orientation relative to the anomeric position of glucopyranoside.

Synthesis and Crystal Structure of 3-Benzyl-6-trichloromethyl-[1,2,4] triazolo[3,4-b][1,3,4]thiadiazole

The title compound 3-benzyl-6-trichloromethyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole I （C11HTC13N4S, Mr = 333.62） has been synthesized, and its structure was determined by elemental analyses, IR, ^1H NMR, ^13C NMR, and X-ray diffractions. The crystal is of triclinic, space group P1^-, with a = 5.898（3）, b = 10.510（4）, c = 11.580（5） A, α = 74.936（7）, β= 75.476（7）, γ = 79.647（7）°, V= 665.9（5）/A^3, F（000） = 336, Z= 2, Dc = 1.664 g/cm^3, 2 = 0.71073A, p = 0.834 mm^-1, the final R = 0.0605 and wR = 0.0900. The secondary bonding interactions （SBIs） S…N and π-π stacking interactions are found in the crystal structure and they link the molecules into a three-dimensional network.

Titrimetric and Spectrophotometric Determination of Some Thiadiazole Derivatives by Using Amplification Reactions

The principle of using amplification reactions of iodine was employed in this paper to estimate the thiadiazole derivatives on basis of their reactions with iodine I chloroform, removal of the excess iodine and determination of the resulting iodide, after oxidation to iodate. The overall reaction gave an amplification of the iodide that is (12) times larger for the compounds: 2-amino-5-mercapto-1,3,4-thiadiazole (I);2,5-dimercapto-1,3,4-thiadiaole (II) and 2,5-diamino-1,3,4-thiadiazole (III) and (36) times for 2,5-dihydrazino-1,3,4-thiadiazole (IV) and (6) times for 5-mercapto-2[(3[5’-nitro-2-’furyl]·methylene)amino]-1,3,4-thiadiazole (V) and 5-mercapto-2[(3[5’-nitro-2-’furyl]-prop-2-enylidene)amino]-1,3,4-thiadiazole (VI). By titration, 1-mL of standard thiosulfate solution was found equivalent to 0.108 mg of (I);0.126 mg of (II), 0.16 mg of (III), 0.041 mg of (IV), 0.40 mg of (V) and 0.435 mg of (VI). Using the spectrophotometric detection for the amplification reaction gave high absorbance values at 605 nm for the blue starch-iodine complex. Beer’s law was obeyed up to 4.0 ppm for compounds (I and II);6.0 ppm for compounds (III, IV and VI) and 5.0 ppm for compound (V). The mechanism of the reactions was proposed and the analytical parameters were evaluated for both methods. The method was applied for synthetic samples of industrial importance. The recovery was comparable while the sensitivity and detection limits were better for the spectrophotometric detection.

Carbazolebis(thiadiazole)-core based non-fused ring electron acceptors for efficient organic solar cells

Non-fused ring electron acceptors(NFREAs)have a broad application prospect in the commercialization of organic solar cells(OSCs)due to the advantages of simple synthesis and low cost.The selection of intermediate block cores of non-fused frameworks and the establishment of the relationship between molecular structure and device performance are crucial for the realization of high-performance OSCs.Herein,two A-D-A’-D-A type NFREAs namely CBTBO-4F and CBTBO-4Cl,constructed with a novel electron-deficient block unit N-(2-butyloctyl)-carbazole[3,4-c:5,6-c]bis[1,2,5]thiadiazole(CBT)and bridging unit 4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophene(DTC)coupling with different terminals(IC-2F/2Cl),were designed and synthesized.The two NFREAs feature broad and strong photoresponse from 500 nm to 900 nm due to the strong intramolecular charge transfer characteristics.Compared with CBTBO-4F,CBTBO-4Cl shows better molecular planarity,stronger crystallinity,more ordered molecular stacking,larger van der Waals surface,lower energy level and better active layer morphology,contributing to much better charge separation and transport behaviors in its based devices.As a result,the CBTBO-4Cl based device obtains a higher power conversion efficiency of 10.18%with an open-circuit voltage of 0.80 V and a short-circuit current density of 21.20 mA/cm^(2).These results not only demonstrate the great potential of CBT,a new building block of the benzothiazole family,in the construction of high-performance organic conjugated semiconductors,but also suggest that the terminal chlorination is an effective strategy to improve device performance.

Synthesis, Nematicidal Activity, and 3D-QSAR of Novel 1,3,4-Oxadiazole/ Thiadiazole Thioether Derivatives

Forty one novel 1,3,4-oxadiazole/thiadiazole thioether derivatives containing phenoxy moiety were designed and synthesized. Bioassay demonstrated that some of them showed remarkable activities against Tylenchufus semipenetruns in vitro and in vivo. Compounds 20, 21, 35 and 39 showed excellent lethal activities after treatment for 48 h in vitro, with LC50 values of 13.4±1.8, 11.7±2.5, 13.7±2.4 and 13.31.1 mg.L-1, respectively, which were obviously superior to fosthiazate （49.1±2.8 mg.L-1） and avermectin （26.6±2.3 mg.L-1）. Compound 23. can effectively control the citrus nema- tode disease caused by T. semipenetruns at 200 mg.L-1 in vivo with （68±3）% inhibitory effect, which was even better than that of avermectin （（63±2）%）. The CoMFA and CoMSIA models of three-dimensional quantitative structure-activity relationships （3D-QSARs） were established. The compound 33 was designed based on the 3D-QSAR models with more vigorous nematicidal activities in vitro （LC50：9.8±1.4 mg.L-1） and in vivo （（70±5）%）. These results demonstrated that compound 33 can be considered as a potential nematicide.

C–H Arylation using acyl thiourea ligands: Applications in the synthesis of 3,6-diaryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles

Synthesis of a series of new 3,6-diaryl-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazoles（5a-o） was achieved by phophine free, C-H arylative cross-coupling of 6-aryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles（4a-o）with suitably substituted iodoanilines using 1-（2-naphthoyl）-3-（4-bromophenyl）thiourea as a ligand.The requisite triazolothiadiazoles（4a-o） were obtained by the condensation of 4-amino-1,2,4-triazole-3-thiol（3） with suitably substituted aromatic acids in the presence of phosphoryl chloride.

Improved Antiproliferative Activities of a New Series of 1,3,4-Thiadiazole Derivatives Against Human Leukemia and Breast Cancer Cell Lines

Twenty-two novel 1,3,4-thiadiazole derivatives were synthesized using different aromatic acids as starting materials, followed by cyclization, coupling and deprotection reaction. The structures of all the target compounds were identified by means of IH nuclear magnetic resonance（NMR）, laC NMR and high resolution mass spectrometer（HRMS）. Further biological evaluations were performed for chronic myelogenous leukemia cell and breast cancer cell. The results suggest that most of the target compounds exhibit potent anti-proliferative activities. Especially, compound 5b shows better antiproliferative activities against MDA-MB-231 and K562 cell lines compared with gossypol.

Benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole-porphyrin-based near-infrared dyes

Benzo[1,2-c;4,5-cʹ]bis[1,2,5]thiadiazole(BBT)has intrinsic diradical character and herein it is used to construct organic near-infrared(NIR)dyes together with the aromatic porphyrin unit.Three BBT-porphyrin hybrid dyes 1-3 with different linkage modes are synthesized by Pd-catalyzed Sonogashira crosscoupling between meso-ethynylene porphyrin units and monobromo-/dibromo-BBT,or through unexpected homocoupling between the BBT units.They all possess small open-shell diradical character and display intense NIR absorption in the range of 800-1000 nm.They also exhibit amphoteric redox behavior.BBT-based diradicaloids are thus good candidates for organic NIR dyes.

Studies on condensed heterocyclic compounds II.Synthesis and antibacterial activity of 3-(4'-pyridyl)-6-aroylamino/arylamino-S-triazolo[3,4-b]-1,3,4-thiadiazoles

3-(4′-Pyridyl)-4-amino-5-mercapto-1,2,4-triazole(1)reacted with aroyl isothiocyanates 2a-1 to yield twelve novel 3-(4′-pyridyl)-6-aroylamino-S-triazolo[3,4-b]-1,3,4-thiadiazoles,4a-1. Triethylamine was necessary for the condensation of 1 with phenyl isothiocyanate(3)to give 3-(4′- pyridyl)-6-phenylamino-S-triazolo[3,4-b]-1,3,4-thiadiazole(6).The structures were confirmed by the elemental and spectral analyses.Their antibacterial activity against B.Subtilis,E.Coli,E. aerogenes and S.aureus was observed preliminary.

Novel 1,3,4-(thiadiazol-2-ylamino) methyl-5-(pyridin-4-yl)-1,3,4-oxadiazol-2-thiones: synthesis, docking and antimycobacterial testing

In the present study, a novel series of Mannich bases of 3-substituted 5-(pyridin-4-yl)-1,3, 4-oxadiazol-2-thione derivatives were synthesized. Docking study was performed to rationalize the possible interactions between the synthesized com-pounds and active site of 14DM. The test compounds were screened for antimycobacterial activity using Middlebrook 7H9 medium against M. tuberculosis H37Rv (ATCC 27294) as well as Isoniazid (INH) resistant clinical strain. Among the series 5c and 5a are found to be most potent (susceptible) while the compound 5f did not show activity against M. tuberculosis H37Rv (resistant). The SAR study reveals the importance of substitutions at para position for good activity.

Two Discrete Cu-Complexes Constructed from a Multidentate N-Containing Dinucleating Ligand

Two comparable discrete complexes [CuⅡ（CH3CN）2L2]·2（ClO4） 1 and [CuI2I2L2]·（DMF）2 2 were successfully synthesized by the reaction of CuⅡ and CuⅠ salts with a novel dinucleating ligand 2,5-bis（3-pyridinylmethylthio）-1,3,4-thiadiazole）（L）,respectively.Complex 1 presents a single nuclear structure while 2 has a dimeric structure where two CuI ions are doubly bridged by halide ions in a μ2-fashion.Both discrete molecules were outspreaded into a one-dimensional supramolecular chain via aromatic interactions such as C–H…π and π…π interactions.

Rhodium-Catalyzed Transannulation of 1,2,3-Thiazoles with Alkynes for the Direct Synthesis of Thiochromenones

A rhodium-catalyzed denitrogenative carbonylation of 1,2,3-thiadiazole with alkynes to construct(benzo)thiochromenones is developed.Both terminal and internal alkynes were compatible in this[3+2+1]cycloaddition,affording a broad range of poly-substituted thiochromenones.Unsymmetrical alkyne substrates exhibited good regioselectivity.