Spectroscopic and structural studies of the 2D Mn(II) coordination polymer from a bridging Noxa, Npy bidentate ligand; tetra-n-butylammonium[5-(3-pyridyl)-1,3,4-oxadiazole-2-thiolate]

A coordination polymer {[Mn(3-pyt)₂(H₂O)₂][N(n-Bu)₄]⁺[3-pyt]⁻}_n (3) has been synthesized from the reaction of tetra-n-butylammonium[5-(3-pyridyl)-1,3,4-oxadiazole-2-thiolate] {[N(n-Bu)₄]⁺[3-pyt]⁻} and Mn(OAc)₂ · 4H₂O. The ligand and the Mn(II) complex 3 have been characterized by elemental analyses, IR, ¹H and ¹³C NMR spectroscopy, in addition 3 has also been studied crystallographically. The single crystal X-ray structure of the 3 shows that the ligand is bonded to Mn(II) via its pyridyl and oxadiazole nitrogen atoms. This bonding pattern connects the Mn(II) centres to afford an uniform two dimensional coordination frame work where the [Mn(3-pyt)₂(H₂O)₂]_n molecules are stacked in a parallel layers. The overall arrangement of molecules in crystal lattice results in open channels in which the enclosed tetra-n-butylammonium cations are stabilized by anionic oxadiazole molecules through N⁺···S⁻ ionic interactions.     

Synthesis of N-pyrimidin[1,3,4]oxadiazoles and N-pyrimidin[1,3,4]-thiadiazoles from 1,3,4-oxadiazol-2-amines and 1,3,4-thiadiazol-2-amines via Pd-catalyzed heteroarylamination

An efficient and practical procedure was developed to prepare various N-pyrimidin[1,3,4]oxadiazole and thiadiazole scaffolds using a Buchwald-type coupling. The products of this reaction are otherwise difficult to access and could be used as building blocks in drug design.     

Thermoluminescence of the blue light-emitting system based on poly(9-vinylcarbazole) doped with a pyrazoloquinoline dye

We have investigated the charge carrier trapping and recombination mechanisms in electroluminescent systems based on poly(9-vinylcarbazole)/2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole blend, used as the matrix, and the deep blue light-emitting pyrazoloquinoline dye-1-H-pyrazolo[3,4-b]quinoline (PAQ8) dopant. The thermoluminescence studies have shown that the charge carrier trapping occurs on the dye molecules as well as on the matrix components. The traps localized on the PAQ8 molecules compete with the others available in the system, however at higher concentrations of the dye a role of these traps increases. Spectral analyses of the thermoluminescence have indicated that even at low concentration of PAQ8, the dye molecules constitute the dominating recombination centres in the system.     

Synthesis,characterisation and mesomorphic behaviours of non-symmetrically substituted 1,2,4- and 1,3,4-oxadiazole derivatives

Two series of non-symmetrically substituted bent-core mesogens derived from the central 3,5 and 2,5 cores of the 1,2,4- and 1,3,4-oxadiazole derivatives, respectively, containing ether and ester linkage have been synthesised by several straightforward synthetic procedures, and their mesomorphic behaviour was studied by optical polarising microscopy (OPM) and differential scanning calorimetry (DSC). The last five homologues of the 1,2,4-oxadiazole series exhibit a monotropic nematic phase on cooling, while the 1,3,4-oxadiazole derivatives do not show any liquid crystalline properties but rather a crystal to isotropic transition is observed by OPM. We show that the bent angles of the 1,2,4- and 1,3,4-oxadiazole rings are crucial in observing the liquid crystal (LC) phases formed, and also that the length of the alkyl substituent is observed to have a significant effect on the nature of the LC phases.     

Updates on synthesis and biological activities of 1,3,4-oxadiazole: A review

The new era of heterocyclic moieties which are developed in the decades plays a very important role in the treatment of various diseases. Among them are 1,3,4-oxadiazoles, a heterocyclic five-membered ring which plays an vital role in the development of newer medicinal compounds for treating various biological activities, such as proliferation of cells, tuberculosis, allergy, viral diseases, etc. The present review will summarize the various synthetic approaches which will be correlated with the biological activities so that the information in future may be used by many researches to give a path breaking lead in the field of medicinal chemistry.     

新型二唑类4-氨基喹唑啉衍生物的合成及其抗肿瘤活性

N-(3-氯-4-氟苯胺基)-7-(3-氯丙氧基)-6-甲氧基喹唑啉-4-胺与一系列取代二唑类化合物经取代反应合成了6个新型的二唑类4-氨基喹唑啉衍生物(3a~3f),其结构经1H NMR,13C NMR,IR及元素分析表征。用MTT法初步测定了3a~3f对前列腺癌细胞(PC-3)和人乳癌细胞(Bcap-37)的抑制率。结果表明:N-(3-氯-4-氟苯基)-6-甲氧基-7-{3-[5-(4-硝基苯基)-1,3,4-噻二唑-2-巯基]丙氧基}喹唑啉-4-胺和N-(3-氯-4-氟苯基)-7-{3-[5-(4-氯苯基)-1,3,4-噁二唑-2-巯基]丙氧基}-6-甲氧基喹唑啉-4-胺在用药量为10μmol·L-1时对PC-3的抑制率分别为66.8%和72.2%。     

Synthesis and Structure of trans-1,2-Bisaromatic Heterocycle Substituted Cyclopropanes

Trans-1,2-bis(2'-(5 '-phenyl-1 ',3',4'-oxadiazolyl)) cyclopropane (BDCP) and its eleven substituted novel derivatives were synthesized. Besides four derivatives of l,2-bis(2'-(5'-phenyl-l ' , 3 ' , 4 ' -ox-adiazo1yl))ethane (BPDS) were also synthesized as model compounds. The crystal structure of ethyl BDCP was determined and the cyclopropane ring was found to be able to transmit conjugation between the aromatic groups directly bonding with it by studying the ultraviolet and fluorescent spectra of the above compounds.     

2-(4-Biphenylyl)-1,3,4-oxadiazoles: synthesis and mesogenic studies

A series of 2-(4-biphenylyl)-1,3,4-oxadiazoles bearing alkyl or alkoxy substituents at the 4? position, and a hydrogen, or alkyl substituent (linear, branched, fluorinated or functionalised) at the 5 position were synthesised and characterised (51 compounds). Their mesogenic properties were evaluated using differential scanning calorimetry and polarising optical microscopy. Results show that substitution of the 1,3,4-oxadiazole ring for a terminal benzene ring in a conventional p-terphenyl enriched the mesogenic properties. Most of the new oxadiazole compounds exhibit either monotropic or enantiotropic smectic A mesophases with widths ranging from 3 to 50°C. A few compounds (short tailed) exhibit nematic phases and some compounds with branched or fluorinated alkyl substituents at the 5 position are also mesogenic.     

有机电致发光材料噁二唑衍生物的合成

由酰氯与各种酰肼反应得到中间体4，进而用三氯氧磷脱水闭环，合成了一系 列1，3，4-噁二唑衍生物5，用~1H NMR，IR，MS和元素分析对其结构进行了确证。     

Synthesis and Crystal Structure of 2-p-Methyloxyphenyl- 3a-（2-phenyl-1,2,3-triazole-4-yl）-3,4-dihydro-1,2,4- oxa-diazolo[4,5-d][1,5] Benzothiazepine

The title compound2-p-methyloxyphenyl-3a-(2-phenyl-1,2,3-triazole-4-yl)-3,4- dihydro-1,2,4-oxa-diazolo[4,5-d][1,5] benzothiazepine (C31H25N5O2S, Mr = 531.63) has been syn- thesized and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to triclinic, space group P1 with a = 10.888(2), b = 15.115(3), c = 16.702(3), α = 99.90(3), β = 95.21(3), γ = 100.41(3)o, V = 2642.1(9) nm3, Dc = 1.336 g/cm3, Z = 4, F(000) = 1112, μ = 0.162 mm-1 ,λ(MoKα) = 0.071073 nm, R = 0.0357 and wR = 0.1126 for 10620 observed reflections with I > 2σ(I). X-ray analysis reveals that the molecular backbone consists of a tricyclic system with the central seven- membered ring in a twisted boat-like conformation.