Search results for "PYRAZOL"
showing 10 items of 720 documents
Improving the photocatalytic H2 evolution activity of Keggin polyoxometalates anchoring copper-azole complexes
2021
Eliminating the use of precious metals as cocatalysts and using visible light are two important aspects in the field of photocatalytic H2 evolution with polyoxometalates (POMs) as photosensitizers. Here we present two new POM-based materials: [CuII5(2-ptz)6(H2O)4(GeW12O40)]·4H2O (1) and [CuI2(ppz)4][H2GeW12O40]·8H2O (2) (2-ptz = 5-(2-pyridyl) tetrazole, ppz = 3-(pyrid-4-yl) pyrazole) synthesized with the Keggin type [GeW12O40]4− (GeW12) polyanion and copper-azole complexes. The optimum photocatalytic H2 evolution rate of compound 1 without a noble metal cocatalyst is 3813 μmol g−1 h−1, which is 7.6 times higher than that of compound 2 and more than 27 times higher than that of bare GeW12 po…
Synthesis and spectroscopic investigations (IR, NMR and Mössbauer) of tin(IV) and organotin(IV) derivatives of bis(pyrazol-1-yl) alkanes: X-ray cryst…
1995
A series of 1:1 adducts of the type [(L)R(n)SnX(4-n)] . zH(2)O (L = bis(4-methylpyrazol-1-yl)methane (L(4)), bis(3,4,5-trimethylpyrazol-1-yl)methane (L(T)), 1,2-bis(pyrazol-1-yl)ethane (L(A)) or 1,2-bis(3,5-dimethylpyrazol-1-yl)ethane (L(B)); R = Me, Et, Bu or Ph; X = I, Br or Cl; n = 0, 1 or 2; z = 1, 1.5 or 2), and the likely polynuclear [(L(A))(5)(SnCl4)(4)] . (H2O)(5) and [(L(B))(2)(SnCl4)(3)] . 1/2[Et(2)O] have been characterized in the solid state and in solution by analyses, spectral (IR, Mossbauer, and H-1, C-13 and Sn-119 NMR) data and conductivity measurements. When L(T) reacts with SnCl4, cleavage of a carbon (sp(3))-nitrogen bond was observed and the adduct [(3,4,5-trimethylpyra…
Recent Advances in Catalytic Enantioselective Synthesis of Pyrazolones with a Tetrasubstituted Stereogenic Center at the 4-Position
2020
AbstractPyrazolone [2,4-dihydro-3H-pyrazol-4-one] represents one of the most important five-membered nitrogen heterocycles which is present in numerous pharmaceutical drugs and molecules with biological activity. Recently, many catalytic methodologies for the asymmetric synthesis of chiral pyrazolones have been established with great success, specially, for the synthesis of pyrazolones bearing a tetrasubstituted stereocenter at C-4. This review summarizes these excellent research studies since 2018, including representative examples and some mechanistic pathways explaining the observed stereochemistry.1 Introduction2 Catalytic Enantioselective Synthesis of Chiral Pyrazolones with a Full Car…
Hsp60 Inhibitors and Modulators
2019
In this chapter, we focus on the 60 KDa Heat Shock Protein (Hsp60) and discuss some of its biological, molecular and pathological features. The structural and mechanistic aspect of the Hsp60 folding cycle will be also presented. We further illustrate how Hsp60 may be involved in many diseases and therefore considered as an effective therapeutic or theranostic target. Finally, the state-of-the-art on the development of Hsp60 and bacterial GroEL inhibitors and modulators of their expression will be illustrated. This is discussed in the light of a negative chaperonotherapy, and the consequent development of inhibitors, as well as positive chaperonotherapy, in the event its excessive activity i…
Bis[3-methyl-5-(pyridin-2-yl)-1H-pyrazol-4-yl] selenide methanol hemisolvate
2014
The asymmetric unit of the title compound, C18H16N6Se·0.5CH3OH, contains two independent molecules of bis[3-methyl-5-(pyridin-2-yl)-1H-pyrazol-4-yl] selenide with similar C—Se—C bond angles [99.30 (14) and 98.26 (13)°], and a methanol molecule of solvation. In one molecule, the dihedral angles between pyrazole and neighbouring pyridine rings are 18.3 (2) and 15.8 (2)°, and the corresponding angles in the other molecule are 13.5 (2) and 8.3 (2)°. In the crystal, the selenide and solvent molecules are linked by classical O—H...N and N—H...N hydrogen bonds, as well as by weak C—H...O and C—H...π interactions, forming a three-dimensional supramolecular architecture.
4-(4-Fluorophenyl)-1-(4-nitrophenyl)-3-(pyridin-4-yl)-1H-pyrazol-5-amine
2012
In the crystal structure of the title compound, C20H14FN5O2, the pyrazole ring forms dihedral angles of 59.3 (2), 25.6 (2) and 46.0 (2)° with the directly attached 4-fluorophenyl, pyridine and nitrophenyl rings, respectively. The crystal packing is characterized by intermolecular N—H...N and N—H...O hydrogen bonds.
Curcumin-derived pyrazoles and isoxazoles: Swiss army knives or blunt tools for Alzheimer's disease?
2007
Curcumin binds to the amyloid beta peptide (Abeta) and inhibits or modulates amyloid precursor protein (APP) metabolism. Therefore, curcumin-derived isoxazoles and pyrazoles were synthesized to minimize the metal chelation properties of curcumin. The decreased rotational freedom and absence of stereoisomers was predicted to enhance affinity toward Abeta(42) aggregates. Accordingly, replacement of the 1,3-dicarbonyl moiety with isosteric heterocycles turned curcumin analogue isoxazoles and pyrazoles into potent ligands of fibrillar Abeta(42) aggregates. Additionally, several compounds are potent inhibitors of tau protein aggregation and depolymerized tau protein aggregates at low micromolar …
Lack of nucleophilic addition in the isoxazole and pyrazole diketone modified analogs of curcumin; implications for their antitumor and chemosensitiz…
2009
Curcumin (CUR) can be considered as a good lead compound for the design of new anticancer drugs. Further, structure-activity relationship studies may clarify the importance of the redox activities in the antitumor effects of the drug. We have elaborated the alpha,beta-unsaturated 1,3-diketone moiety of CUR into the isoxazole (ISO) and pyrazole (PYR) derivatives. These derivatives should be much less prone to nucleophilic addition than CUR and benzyl mercaptan addition analyses showed that indeed they do not form isolable conjugated products. When compared with CUR, ISO and PYR exhibited increased cell growth inhibitory and pro-apoptotic effects in liver cancer HA22T/VGH cells as well as in …
Gallium-68 and scandium-44 labelled radiotracers based on curcumin structure linked to bifunctional chelators: Synthesis and characterization of pote…
2019
Abstract Curcumin metal complexes showed widespread applications in medicine and can be exploited as a lead structure for developing new tracers for nuclear medicine application. Herein, the synthesis, chemical characterization and radiolabelling with gallium-68 and scandium-44 of two new targeting vectors based on curcumin scaffolds and linked to the chelators 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA) and 1,4-bis(carboxymethyl)-6-[bis(carboxymethyl)]amino-6-methylperhydro-1,4-diazepine (AAZTA) are reported. Synthesis of the precursors could be achieved with a 13% and 11% yield and radiolabelling generally afforded rapid incorporation under mild conditions (>95%). Sta…