Design, Synthesis, Crystal Structure and Photophysical Properties of New Oxadiazole Extended Viologen Fluorophore

Viologens (N,N'-dimethyl-4,4-bipyridinium) are advanced functional materials, found important applications in electrochromic devices, molecular machines, organic batteries, and carbohydrate oxidation catalysts in alkaline fuel. In this article, we investigated the design, synthesis and photophysical properties of N,N'-dimethyl-2,5-Bis(pyridinium)oxadiazole 4 and its precursor 2,5- Bis(pyridine)oxadiazole 2. The crystal structure and photophysical properties of viologen 4 and precursor 2 have been determined. The viologen molecule 4 crystallized in monoclinic form, space group P21/n with four molecules in unit cell. Precursor molecule 2 also crystalized in monoclinic form, space group C2/c with four molecules in unit cell. From X-rd data, we found three cations in the molecular structure of viologen molecule 4, which is unusual in viologens. In the three-dimensional molecular packing diagram of molecule 4, the three cations and iodate anions are stabilized by C···C, C···I, N···I, N···H, H···I, N—H···I and C—H···I. The dihedral angle between planes having oxadiazole and two benzene rings are 5°and 8°, suggesting the molecule 4 is a slightly strained one. The molecular structure of precursor molecule 2 stabilized by C···C and N···H short contacts between the molecules. The molecule 4 displayed strong absorbance at 315 nm and emissions between 390 - 410 nm.

Design,Synthesis and Antitumor Activity of Fluoroquinolone C3 Heterocyclic Bis-oxadiazole Methylsulfide Derivatives Derived from Levofloxacin

To discover an efficient route for the shift from an antibacterial fluoroquinolone to an antitumor one based on the mechanistic similarities between targeting topoisomerases and the eukaryotic ones,two series of the title compounds,C3 bis-oxadiazole methylsulfides 6a―6h and corresponding dimethylpiperazinium iodides 7a―7h derived from levofloxacin 1 were designed and synthesized.Their in vitro antiproliferative activities against Chinese hamster ovary cell line（CHO）,murine leukemia cell line（L1210） and human leukocytoma cell line（HL60） were evaluated by MTT assay,and inhibitory effect on DNA topoisomerase IIα was also measured by means of densitometric assay.

Synthesis and photophysical and electrochemical properties of new cyclometalated platinum complex containing oxadiazole ligand

A new cyclometalated platinum complex containing 2, 5-bis(naphthalene-1-yl)-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its platinum complex were investigated. A characteristic metal-ligand charge transfer absorption peak at 439 nm in the UV spectrum and a strong emission peak at 625 nm in the photoluminescence spectrum were observed for this complex in dichloromethane. Cyclic voltammtry (CV) analysis shows that the EHOMO (energy level of the highest occupied molecular orbital) and ELUMO (energy level of the lowest unoccupied molecular orbital) of the platinum complex are about 、5.69 and 、3.25 eV, respectively, indicating that the oxadiazole-based platinum complex has a potential application in electrophosphorescent devices used as a red-emitting material.

Synthesis and characterization of conjugated polymer containing azobenzene and oxadiazole units

A novel conjugated polymer containing azobenzene and oxadiazole units was synthesized through multi-step synthesis. The structures and properties of monomer and polymer were characterized and evaluated with IR, ^1H NMR, UV, TGA and GPC, respectively. Polymer with long side chain of alkoxy shows good solubility, thermal stability and photoisomerization property.

Synthesis of Pyridyl Polyheterocyclic Oxime-ether Schiff Bases Containing s-Triazole and Oxadiazole Subunits

4-Amino-5-pyridin-4-yl-s-triazole-3-thiol （1） was sequentally reacted with 3-chloro-1- phenylpropan-1-one to afford 3-（4-amino-5-pyridin-4-yl-s-triazole-3-sulfanyl）-1-phenylpropan-1- one （2） followed by oximation with hydroxylamine hydrochloride and etherification with 5-aryl-[13,4]oxadiazole-2-cbloromethanes to the corresponding oxime （3） and oxime-ethers （4a-e）, respectively. The condensation of compounds 4 with salicylaldehyde gave the title compounds （5a-e）. The antibacterial activity in vitro against Gram-postive （G^＋） and Gram negative （G） bacteria was primarily evaluated.

Synthesis and Bioactivity of Arecoline Derivatives Containing Amino-s-triazole Coupled Oxadiazole

5-（5＂-Substituted phenyl-[1＂,3＂,4＂]oxadiazol-2＂-yl methylsulfanyl）-3-pyridin-3′-yl- [1,2,4] triazol-4-yl amines la-j were quaternarized with methyl iodide to afford the corresponding methyl pyridinium salts 2a-j. The reduction of compounds 2 with NaBH4 in methanol gave the target compounds 5-（5＂-substituted phenyl-[1＂,3＂,4＂]oxadiazol-2＂-yl methylsulfanyl）-3-（1′-methyl-1＇,2＇,5＇,6＇-tetrahydropyridin-3＇-yl）-[1,2,4]triazol-4-ylamines 3a-j. The endothelium vascular relaxing activity of the target compounds were screened.

Effects of high pressure on the Raman and fluorescence emission spectra of two novel 1,3,4-oxadiazole derivatives

The effects of pressure on the fluorescence emission and Raman spectra of 1,4-bis[（4-methyloxyphenyl）-1,3,4-oxadiazolyl]- 2,5-bisheptyloxyphenylene （OXD-2） and on the fluorescence emission spectra of 1,4-bis[（4-methylphenyl）- 1,3,4-oxadiazolyl]phenylene （OXD-1） are investigated using a diamond anvil cell. With the increase of pressure, the intensity of the fluorescence emission increases and reaches maxima at 13GPa for OXD-1 and at 9.6GPa for OXD-2. The effect of pressure on the peak position of the emission shows a similar trend, red shift with the increase of pressure. But at higher pressures, the intensity of emission drops down dramatically. The Raman spectra of OXD-2 indicate that there appears a structural change at ca 3GPa.

BLUE LIGHT-EMITTING POLY(FLUORENE-CO-BENZENE) CONTAINING AN OXADIAZOLE MOIETY

A new kind of polyfluorene containing oxadiazole as the side chain was synthesized. The introduction of oxadiazole moiety as more bulky group prevents the aggregation and reduces the crystallinity of the polymers. Efficient intramolecular energy transfer from oxadiazole moiety to the conjugated backbone has been realized, leading to 70% improvement of photoluminescence quantum efficiency of the designed polymers. Compared with PAF, the PFOXD exhibits significant improvement in electroluminescence properties, with luminous efficiency of 0.8 cd/A and maximum luminance of 1800 cd/m2.

Synthesis,Crystal Structure and Antifungal Activity of 2-((2-Fluorobenzyl)thio)-5-(pyridin-4-yl)-1,3,4-oxadiazole

The title compound 2-（（2-fluorobenzyl）thio）-5-（pyridin-4-yl）-1,3,4-oxadiazole（C_（14）H_（10）FN_3OS） was synthesized,and its structure was confirmed by ~1H NMR,MS,elemental analyses and X-ray diffraction. It crystallizes in the monoclinic system,space group P21/n with a = 11.541（16）,b = 8.226（12）,c = 13.683（19） ？,β = 94.872（17）o,V = 1294（3） ？~3,Z = 4 and R = 0.0648 for 2198 observed reflections with I 〉 2σ（I）. The preliminary biological test shows that the title compound has good activity against Pythium ultimum with inhibitory to be 100%.

Green-Light Electroluminescence of Conjugated Copolymer Containing p-Phenylene-ethynylene and Oxadiazole

The title copolymer(PDEBO) was synthesized. The thermal characteristics of the polymer were determined by means of DSC and TGA, revealing that the polymer has a good thermal stability. The X-ray diffraction measurements of the thin films showed that the polymer is disorder. Electroluminescence(EL) in the green region of the spectrum with a maximum at 500 nm was observed from the polymer films sandwiched between indium-tin-oxide and an Al electrode.

Preparation and property of a novel soluble oxadiazole-containing functional polyacetylene

A novel high molecular weight functional polyacetylene bearing oxadiazole group as a pendant, poly{4-[2-（4-octoxyphenyl）-1,3,4-oxadiazolyl]-benzenyloxypropynylene}, was synthesized by [Rh（nbd）Cl]2-Et3N catalyst. The polymer was soluble in common organic solvents such as CHCl3 and THE The structures and properties of monomer and polymer were characterized and evaluated with FTIR, NMR, UV, TGA, GPC, and CV, respectively. The results show that the polymer possesses high thermal stability and well electron-injection property.

Synthesis and characterization of a novel main chain oxadiazole-based copolymer for n-type solar cell material

A novel oxadiazole-based copolymer has been successfully synthesized through the palladium-catalyzed cross-coupling polycondensation method. The copolymer P is soluble in common organic solvents. Its structure has characterized by ^1H NMR, ^13C NMR, gel permeation chromatagraphy （GPC）, UV-vis absorbance （Abs） and photoluniminescence （PL） spectroscopy, and cyclic voltammetry （CV）. Investigation of its optical properties revealed that it is yellow emitting material, and the electrochemical analysis showed that P was well suited poly （2,5-dioctyloxy-p-phenylenevinylene） （PDOCPV） for photovoltaic devices, so the copolymer P is able to act as an electron acceptor in combination with PDOCPVas the electron donor to quench photoluminescence of the copolymer in the blend, indicative of the efficient photoinduced electron transfer from the PDOCPV to the P.

Synthesis and Crystal Structure of (p-{2-[p-(5'-Phenyl-1',3',4'-oxadiazole-2'-yl)-phenyl]- vinyl}-phenyl)-di-p-tolyl-amine

The crystal of the title compound (C36H29N3O,Mr = 519.62) has been prepared and structurally determined by X-ray single-crystal diffraction. It crystallizes in triclinic P space group with the crystal cell parameters: a = 12.544(4), b = 14.112(4), c = 17.770(5)? = 96.150(6), = 106.112(5), = 107.156(5)? V = 2825.7(14) 3, Z = 4, Dc = 1.221g/cm3, (MoK? = 0.074 mm-1 , F(000) = 1096,the final R = 0.0747 and wR = 0.1632 for 4713 observed reflections with I >2(I). The E-stereochemistry of the title compound can be confirmed by the result of the X-ray diffraction analysis.

Structural Studies of 3-(1,2-O-Isopropylidene-α-D-xylosyl)-5-phenyl-1,2,4-oxadiazole

1、2－O－Isopropylidene－3－C－cyano－5－O－benzoyl－α－D－xylose 2 was preparedstereoselectively from 1，2－O－isopropylidene－3－oxo－5－O－benzoyl－α－D－xylose 1．The structure of 2was studied by two－dimensional NMR spectroscopy in conjunction with X－ray crystallography of itscorresponding 5－phenyl－1，2，4－oxadiazole isocarbonucleoside derivative 3． The absoluteconfigurations of 2 and 3，and conformation of 3 are described herein．

Synthesis of 3-Substituted-6-(2,4-Dichlorophenyl)-s-Triazolo[3.4-b]-1,3,4-Oxadiazoles

Fourteen new 2-acylhydrazino-5 -(2,4-dichlorophenyl)-1, 3,4 -oxadiazo les were prepared by nucleophilic displacement of acylhpeine at the 2-position of 2-methylsulfonyl-5-(2,4-dichlorophenyl)-1,3,4-oxadiazole. Fourteen new 3-substhad-6-(2,4-dichlorophenyl)-s-triazolo [3,4-b]-1,3,4-oxadiazoles were obtained by treating 2 -acylhydrazion- 5-(2,4-dichlorophenyl )- 1, 3,4-oxadiazoles with K2CO3 solution. All the new compounds showed significant antibacterial activity

An updated study of traditional medicines to the era of 1,3,4 oxadiazole derivatives for malaria treatment

Discovering potent drug candidates requires new antimalarial targets.For this reason,antimalarial drug researchers focus on developing new drug candidates on promising targets.In the identification of these targets,a basic understanding of the metabolism and biochemical processes of malaria parasites such as Plasmodium falciparum can prove invaluable.However,malarial resistant parasites are becoming more and more significant issues as antimalarial medications progress.Antimalarial drugs are becoming increasingly resistant,thus the search for new molecules is very important task.Artemisinin based combination therapies are becoming more popular for treating malaria.This will ultimately lead to the selection of resistance due to their extensive and indiscriminate deployment.Alternative artemisinin-based combination therapies are therefore required.There is an interest in finding suitable antimalarial compounds based on their potential effectiveness against malaria.The potential activity of 1,3,4 oxadiazole analogues against malarial infections is a major draw of the search for suitable antimalarial compounds.This review identifies existing antimalarial drugs that have own therapeutic effects and evaluating their feasibility for developing novel synthetic antimalarial derivatives.

Design and Synthesis of Some New Oxadiazole Derivatives as Anticancer Agents

In this work, some new oxadiazole derivatives have been prepared, by reacting phenyl hydrazine and acetic anhydride together, which furnished 2,4-dimethyl-4-phenyloxadiazole. This product was reacted with a series of aromatic aldehydes, to obtain a series of oxadiazole derivatives. These derivatives were characterized by TLC, melting points, infrared red, proton nuclear magnetic resonance, carbon thirteen nuclear magnetic resonance and mass spectroscopy. Finally, these synthetized derivatives were tested for antiproliferative activity by two different cell lines. MCF-7 (Breast cancer cell line) and HepG2 (Liver cancer cell line) were used to assess the antiproliferative activity of the prepared compounds.

High-efficiency saturated red emission from binuclear cyclo-metalated platinum complex containing 5-(4-octyloxyphenyl)-1,3,4-oxadiazole-2-thiol ancillary ligand in PLEDs

A novel red-emitting binuclear platinum complex （dfppy）zPtz（C^OXT）z was synthesized and characterized, in which dfppy represents 2-（4＇,6＇-difluorophenyl）pyridinato unit and CsOXT is abbreviated for 5-（4-octyloxyphenyl）-1,3,4-oxadiazole-2-thiol as a bridging ancillary ligand. Its photophysical, electrochemical and electroluminescent characteristics were primarily studied. The made single-emissive-layer （SEL） polymer light-emitting devices using （dfppy）2Ptz（CsOXT）2 as emitter exhibited a satu- rated red emission peaked at 620 nm. The best device performances were obtained in the device at 8 wt% dopant concentration, with a maximum external quantum efficiency of 8.4%, a current efficiency of 4.2 cd/A and brightness of 3228 cd/m~. This work provides an effective approach to obtain high-efficiency red emission through construction of new binuclear platinum complex and its doped SEL devices.

Design, Synthesis and Herbicidal Activity of Novel Sulfonylureas Containing Triazole and Oxadiazole Moieties

Three novel series of 5-substituted sulfonylurea derivatives were designed and synthesized via introducing a triazole or oxadiazole ring at the 5th position of the benzene ring in classical sulfonylurea herbicides. All the target compounds were confirmed by means of IH nuclear magnetic resonance（NMR）, 13C NMR and elemental analysis. The bioassay results show that the target compounds containing an oxadiazole ring at the 5th position display moderate to excellent herbicidal activities against Brassica campestris and Amaranthus retroflexus under soil treatment. Especially, compounds zdk20, zdk21 and zdk22 possess 98.6%, 96.5% and 94.5% inhibition rates, respectively, against Amaranthus retroflexus at a concentration of 75 g/ha（1 ha=1× 104 m2） under soil treatment, which approach to those of the commercial herbicide chlorsulfuron.

Electrosynthesis of oxadiazoles from benzoylhydrazines

A highly efficient conformation from facile benzoylhydrazines was developed under electrochemical condition. A variety of oxadiazoles were obtained with good yields by virtue of this new method.