Novel four-hydrogen-bond assembled oligoamide dimer with pyrazoline moieties and its photoluminescent properties

In this paper, the synthesis and characterization of a triarylpyrazoline modified four-H-bonded molecular duplex are described. Its molecular structure has been confirmed by ^1H NMR and ESI-MS. The duplex emits strong pure blue light peaking at 448 and 452 nm under UV photoexcitation in solution and solid state, respectively, and its relative photoluminescence quantum efficiency in solution is determined as 0.778 using quinine sulfate as reference. In concentration of 〉40 mmol/L, the duplex can gelate DMSO, and the organogel formed shows good pure blue photoluminescence too. This novel duplex, for its well-defined structure and efficient photoluminescence property, is a prospective candidate for pure blue electroluminescent emitter.

Preparation and Properties of Rare Earth Complexes with 5-Phenyl Pyrazoline Dithioformate

Nine complexes of rare earths with 5 phenyl pyrazoline dithioformate, Na[RE(S 2CNC 9H 9 N) 4· x H 2O (RE=La～Dy, Y, except for Ce and Pm) were synthesized in dry N 2 atmosphere and characterized by elemental analyses, molar conductance, IR spectra, thermal analyses. The results show that the ligands coordinate to the RE ion through two sulphur atom donors. Thermal analyses indicate that the thermal stability of the complex is not higher than that of sodium 5 phenyl pyrazoline dithioformate. The complexes are easily soluble in acetonitrile and tetrahydrofuran. The molar conductance values of the complexes measured in acetonitrile (1 24～1 32×10 -3 mol·dm -3 ) at 25 ℃ are in the range of 86～104 Ω -1 ·cm 2·mol -1 , indicating that they are 1∶1 electrolytes.

Novel fluorene-carzazole-based conjugated copolymers containing pyrazoline and benzothiazole segments for blue light-emitting materials

A series of novel fluorene-carbazole-based copolymers with pyrazoline and benzothiazole units were synthesized successfully through Suzuki coupling reactions. The molecular structures and thermal properties of these polymers were characterized by FTrIR, 1H NMR, DSC and TGA. GPC results indicated that the weight-average molecular weight （Mw） and polydispersity of these polymers were in range （12,0（0）-14,000） and （1.8-2.0）, respectively. The two resulting polymers have high photoluminescence quantum efficiency implying that they may be promising candidates for polymer light-emitting diodes （PLEDs）.

TD-DFT Study on Pyrazoline Derivatives

The molecular structures of ground state and first single excited state for pyrazoline derivatives are optimized with DFT B3LYP method and ab initio “configuration interaction with single excitations”（CIS） method, respectively. The frontier molecular orbital characteristics have been analyzed systematically, and the electronic transition mechanism has been discussed. Electronic spectra are calculated by using TD-DFT method. These results are consistent with those from the experiment.

Syntheses and Crystal Structures of Pyrazoline Derivants

Two pyrazoline derivants 1-(2-benzothiazole)-3-phenyl-5-(3-thiophene)-2- pyrazoline (BPTP) and 1-(2-benzothiazole)-3-(2-thiophene)-5-phenyl-2-pyrazoline (BTPP) have been synthe- sized and their crystal structures were determined by X-ray single-crystal diffraction. Crystal of BPTP belongs to triclinic, space group P1 with a = 9.4430(11), b = 9.9384(13), c = 9.9394(13) ?, α = 83.107(10), β = 79.947(10), γ = 70.221(7)o, V = 862.42(19) ?3, Z = 2, Dc = 1.392 g/cm3, μ(MoKα) = 0.316 mm-1, F(000) = 376, λ = 0.71070 ?, (?ρ)max = 0.348, (?ρ)min = –0.481 e/?3, the final R = 0.0407 and wR = 0.1055 for 2844 observed reflections with I > 2σ(I). Crystal of BTPP is of monoclinic, space group P21/c with a = 11.6158(17), b = 11.2796(18), c = 13.082(2) ?, α = 90, β = 91.087(4), γ = 90o, V = 1713.7(5) ?3, Z = 4, Dc = 1.401 g/cm3, μ(MoKα) = 0.318 mm-1, Mr = 361.07, F(000) = 752, λ = 0.71070 ?, (?ρ)max = 0.322, (?ρ)min = –0.330 e/?3, the final R = 0.0563 and wR = 0.1058 for 3434 observed reflections with I > 2σ(I).

TBPA^(+·) mediated aromatization of 1,3,5-trisubstituted pyrazolines

1,3,5-Trisubstituted pyrazolines were oxidized to the corresponding pyrazoles in high yield with tris（4-bromophenyl）aminium （TBPA＊＊） hexachloroantimonate in chloroform at room temperature.

Synthesis of Pyrazolines Used as Blue Organic Electroluminescence Materials

Three kinds of pyrazolines were designed and synthesized. Their structures were elucidated by IR, (HNMR)-H-1, MS, UV and elemental analysis. Their luminescent properties were determined, which indicated that they had strong blue fluorescent properties. One of them was designed to have good film formation. All the three kinds of pyrazolines can be used as blue organic electroluminescence materials (OELMs).

A Novel Pyrazoline-based Starburst Amorphous Molecular Material

A pyrazoline-containing starburst molecule, 4,4’,4"-tris[(1,3-diphenyl-4,5-dihydro-1H- pyrazol)-5-yl]-triphenylamine (Tris-5-DPP), was synthesized in a facile way, which can form amorphous thin films with glass transition temperature as high as 136 °C.

Design, Synthesis and Biological Evaluation of Novel Antitubercular Agents by Combining Pyrazoline and Benzoxazole Pharmacophores

Various recent reports on Tuberculosis have alarmed an increase in the patient class and subsequent death rates across the globe. Over and above the spread of more dangerous and fatal forms of tuberculosis like MDR-TB i.e. multiple-drug resistance tuberculosis, XDR-TB i.e. extensively-drug resistance tuberculosis & TDR-TB i.e. total-drug resistance tuberculosis has forwarded an urgent need to discover novel antitubercular agents. The current work is aimed at combining two previously well-known pharmacophores (pyrazoline and benzoxazole nucleus) in order to design and synthesize a series of novel benzoxazole-based pyrazoline derivatives. The synthesized target compounds were structurally confirmed by LCMS, 1H-NMR and 13C-NMR analysis. The target compounds were In vitro evaluated against M. tuberculosis H37Rv strain, multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) strains. The In vitro screening results depicted that majority of the target compounds displayed potent activity with MIC in a range of ~0.8 to 6.25 μg/mL. Many compounds were found to be more potent than isoniazid against MDR-TB with MIC value 3.12 μg/mL and XDR-TB with MIC value 12.5 μg/mL. Cytotoxicity assay of these active compounds on VERO cell lines also displayed good selectivity index.

Synthesis and Spectral Characterization of Novel 2-Pyrazoline and Bis-2-Pyrazoline Containing Quinoline Moiety

Eight new compounds containing in their structures substituted quinoline and pyrazole entity were synthesized in good to excellent yield by cyclocondensation reaction of chalcones and hydrazine hydrate. This reaction was conducted in formic acid in presence of BF3·Et2O or in acetic acid. These approaches were extended to bis-chalcones, which delivered functionalized bispyrazolines. The structures of the prepared compounds were confirmed by IR, 1HNMR, 13CNMR and mass spectral analysis.

Formation of 3-Arylpyrazolines and 1-Aroylethyl-3-arylpyrazolines via 3-Aroylethylsydnone with HCl in Ethyl Acetate

Treatment of 3-aroylethylsydnone 1 with HCl leads to 3-arylpyrazoline 2 or 1-aroylethyl-3-arylpyrazoline 3 under different conditions.

An efficient and facile synthesis of novel 1,2,3-triazolyl-N- acylpyrazoline hybrids

An efficient and facile synthesis of a library of hitherto novel 1,2,3-triazolyl-N-acetyl/N-propionylpyrazoline hybrids （16 examples） in excellent yields （90%-96%） has been accomplished from easily accessible 1,2,3-triazolyl chalcone precursors.

Silica-supported 1,3-dichloro-5,5-dimethylhydantoin(DCH) as a useful reagent for microwave-assisted aromatization of 1,3,5-trisubstituted pyrazolines under solvent-free conditions

1,3,5-Trisubstituted pyrazolines are rapidly and conveniently oxidized to their corresponding pyrazoles by 1,3-dichloro-5,5- dimethylhydantoin（DCH） in solution and solvent-free conditions under microwave irradiation.The presence of silica gel as a supporting agent is shown to be effective in reducing the reaction times and increasing the yields.

1,3-Diphenyl-5-(9-phenanthryl)-2-pyrazoline (DPPhP): An Excellent Hole-Transport Material for Use in Organic Light-Emitting Diodes

b Département de Physique, Ecole Polythechnique Fédérale de Lausanne, EPFL, Lausanne, Switzerland c Department of Chemistry, Tsinghua University, Beijing 100084, China An excellent hole-transport material, 1,3-diphenyl-5-(9-phenanthryl)-2-pyrazoline (DPPhP) for OLEDs was studied. This compound not only offers high glass transition temperature (T g=96 ℃), good film forming ability, and high HOMO energy level, but also displays excellent hole-transport property. The electroluminescent device with a simple structure of ITO/DPPhP (60 nm)/AlQ (60 nm)/LiF (0.8 nm)/Al shows an external quantum efficiency as high as 1.6%.

Synthesis and Fluorescent Property of Pyrazoline Derivatives

A series of fluorinated pyrazoline derivatives were synthesized by the reaction of fluorinated chalcone with hy- drazine ArNHNH2 （Ar=4-BrC6F4, 4-CIC6H4, C6Hs, 4-CH3C6H4 and 4-CH3OC6H4）, The structures of all these compounds were fully supported by their spectroscopic data and one of products was further confirmed by X-ray single crystal diffraction analysis. The capability of fluorinated triaryl-2-pyrazolines to detect metal cations was in- vestigated, by monitoring changes in their fluorescence spectra in the presence of Cd^2＋, Co^2＋, Cu^2＋, Mn^2＋, Ni^2＋ and Zn^2＋.

The synthesis and photoactivated cytotoxicity of novel 5-phenyl-3-(2,2':5',2"-terthien-5-yl)-4,5-dihydro-1H-pyrazolines

A series of novel 5-phenyl-3-（2,2＇：5＇,2″-terthien-5-yl）-4,5-dihydro-lH-pyrazolines were synthesized in this report. Their photoactivated cytotoxicities on the 5podoptera litura （SL） cell line were evaluated using the MTT method. It was noticed that the inhibitory activities of all the conjugates was enhanced when irradiated with UV-A light. Compounds 4, 6 and 8 were found to be most effective with inhibition rates of 88.1%, 88.0%, and 90,5%, respectively, For compound B, the inhibition rate value was only slightly enhanced under the irradiation treatment （78.3%） compared to the dark treatment （74.8%）. The relationship analysis between structure and activity showed that the middle thiophene ring played an important role on the inhibitory activities. It was shown that these compounds could be the potential candidates for new photoactivated pesticides.

Visible light catalyzed aromatization of 1,3,5-triaryl-2-pyrazolines by platinum(Ⅱ) polypyridyl complex under oxidant-free condition

With visible light(λ=450 nm) irradiation of a catalytic amount of platinum(Ⅱ) terpyridyl complex, 1,3,5-triaryl-2-pyrazolines can be smoothly converted to their corresponding pyrazoles and hydrogen in quantitative yields with no use of any oxidant at room temperature.

Microwave assisted synthesis and in silico screening of steroidal pyrazolines

The present manuscript describes solid-state synthesis of some reported steroidal pyrazolines by a novel eco-friendly route. The synthesized pyrazolines were compared with those obtained from conventional methods in terms of reaction time and overall yield. A substantial enhancement in reaction rate and yield was observed. The antimicrobial activity and the subsequent molecular docking studies of the steroidal pyrazolines have also been carried out.

Environmentally Benign Synthesis of 2-Pyrazolines and Cyclohexenones Incorporating Naphthalene Moiety and Their Antimicrobial Evaluation

We reported the environmental benign synthesis of chalcones,2-pyrazolines and cyclohexanones under microwave irradiation.Chalcones were obtained by the condensation of each of 2-hydroxyacetophenone derivatives with a-naphthaldehyde under microwave irradiation.The condensation reactions of each of synthesized chalcones with phenyl hydrazine under microwave irradiation in the presence of dry acetic acid as a cyclizing agent gave 2-pyrazolines.Also,the new cyclohexenone derivatives,valuable intermediates to synthesize fused heterocycles,have been prepared by the cyclocondensation of each of hydroxychalcones with ethyl acetoacetate.The structures of the synthesized compounds were elucidated by infrared（IR） spectrometry,nuclear magnetic resonance（NMR）,mass spectrometry（MS） and elmental analysis.The results indicate that unlike classical heating,microwave irradiation results in higher yields with shorter and cleaner reactions.The synthesized compounds were screened for antimicrobial activity against Staphylococcus aureus,Escherichia coli,Candida Albicans and Aspergillus niger.We clarified the effects of different substituents in the tested compounds on the obtaind antibacterial activities and antifungal activities.

Asymmetric catalytic 1,3-dipolar cycloaddition ofα-diazoesters for synthesis of 1-pyrazoline-based spirochromanones and beyond

A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes(up to 97%yield,98%ee with>95:5 dr).Moreover,enantioenriched 2-pyrazoline-based spirochromanones were also accessible by switchingα-substituted diazoesters toα-diazoacetates.The further specific transformations of chiral pyrazoline-based spiro-compounds to spirocyclopropane derivatives were disclosed as well.