SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Tp2Ti [Tp = hydrotris(pyrazol-1-yl)borate] is a stable hard donor complex of divalent titanium that shows controlled reaction chemistry with simple chalcogen oxidants.
The crystal structure of the complex [Cu4(H-2L)2(H2O)2(ClO4)2](ClO4)(2).2H2O where L is a new pyrazole ligand containing 1,5-diaminopentane spacers represents a new form of obtaining metal ion-induced inorganic-organic cages.
A H-bonded pyrazole trimeric motif drives the self-association of bifunctional tetramethyl-4,4'-bipyrazole, yielding highly interpenetrated 3D frameworks and allowing the engineering by design of a novel supramolecular isomer.
Ceric ammonium nitrate (CAN) in methanol-water gave a new N-dearylation of a series of substituted 1-(p-methoxyphenyl) pyrazoles and a 2-(p-methoxyphenyl)tetrazole producing p-benzoquinone and the parent azole in a mole for mole ratio. Application of this reaction to 1-(p-methoxyphenyl) pentazole at -40 degrees C produced p-benzoquinone. 15N NMR spectra suggest that pentazole, HN5, was also produced and held in solution as N5- with Zn2+ ion. The 15N signal from N5- was -10.0 +/- 2.0 ppm in agreement with calculated values.
A new series of pyridyl pyrazolate boron complexes 2a-e have been synthesized, in which 2a-c exhibit remarkable dual fluorescence properties due to the photoinduced electron transfer reaction.
Scorpionates represent one of the most versatile types of tridentate ligand that can coordinate to a wide variety of elements, e.g. from early to late transition metals, and the coordination chemistry of these systems has developed greatly in recent years. This Perspective gives an account of studies on the following aspects: (1) the preparative methods for a new class of heteroscorpionate [RR'C(pz)2] ligand derived from bis(pyrazol-1-yl)methane and (2) the description of metal complexes containing these ligands, examples of which incorporate a range of different metals from the Periodic Table.
New receptors fac-[Re(CO)3(pz)3]BAr'4 (pz = 3,5-dimethylpyrazole or 3(5)-tert-butylpyrazole, Ar' = 3,5-(CF3)2C6H3), synthesized from [Re(OTf)(CO)5] and the pyrazoles, have been found to show a high affinity for chloride.
Compounds [RuII(bipy)(terpy)L](PF6)2 with bipy = 2,2'-bipyridine, terpy = 2,2':6',2"-terpyridine, L = H2O, imidazole (imi), 4-methylimidazole, 2-methylimidazole, benzimidazole, 4,5-diphenylimidazole, indazole, pyrazole, 3-methylpyrazole have been synthesized and characterized by 1H NMR, ESI-MS and UV/Vis (in CH3CN and H2O). For L = H2O, imidazole, 4,5-diphenylimidazole and indazole the X-ray structures of the complexes have been determined with the crystal packing featuring only few intermolecular C-H...pi or pi-pi interactions due to the separating action of the PF6-anions. Complexes with L = imidazole and 4-methylimidazole exhibit a fluorescence emission with a maximum at 662 and 667 nm, respectively (lambdaexc= 475 nm, solvent CH3CN or H2O). The substitution of the aqua ligand in [Ru(bipy)(terpy)(H2O)]2+ in aqueous solution by imidazole to give [Ru(bipy)(terpy)(imi)]2+ is fastest at a pH of 8.5 (as followed by the increase in emission intensity). Coupling of the [Ru(bipy)(terpy)]2+ fragment to cytochrome c(Yeast iso-1) starting from the Ru-aqua complex was successful at 35 degrees C and pH 7.0 after 5 d under argon in the dark. The [Ru(bipy)(terpy)(cyt c)]-product was characterized by UV/Vis, emission and mass spectrometry. The location where the [Ru(bipy)(terpy)] complex was coupled to the protein was identified as His44 (corresponding to His39 in other numbering schemes) using digestion of the Ru-coupled protein by trypsin and analysis of the tryptic peptides by HPLC-high resolution MS.
A series of pyrazole and triazole based dinucleating ligands have been synthesized and their complexation potential for metal ions, which exhibit square planar coordination geometry has been studied. In the case of Cu(2+) the complexation equilibria in solution have been determined using pH titrations. Species with 1 : 1 stoichiometry [CuLH(n)], 2 : 1 stoichiometry [Cu(2)LH(m)], and of dimeric nature [Cu(2)L(2)H(p)], have been detected and their overall stability constants have been measured. The reactivity of the dinuclear species [Cu(2)LH(-1)] towards phosphate ester hydrolysis have shown that the OH-functionality incorporated in some of the ligands does not enhance the hydrolysis rate. Several ligands were reacted with Pt(2+) to give insoluble dinuclear species [Pt(2)LI(3)]. One of them was studied by X-ray diffraction and shows that the two Pt(2+) are bridged by the pyrazolide group and by one I(-). The remaining two positions are occupied by the amino group in alpha position of the heterocyclic ring and a terminal I(-). The nearly planar [Pt(2)LI(3)] units form sheets in the crystals, which are about 4 A apart and thus indicate pi stacking interactions.
In the search for new cholecystokinin (CCK) ligands, ureidopyrazolines were identified in combinatorial libraries using 168 chemically diverse amines. The structure-activity relationship optimisation of this pyrazoline template 4a resulted in novel 3-oxo-1,2-diphenyl-2,3-di-hydro-1H-pyrazol-4-yl)-N'-phenylureas 5a-5o. These novel CCK ligands have shown to act as mixed CCK-A/CCK-B ligands in a [125]I-CCK-8 receptor binding assay. The best pyrazoline 5e of this series displayed an IC50 of 20 and 25 nmol/L for the CCK-A, and CCK-B receptor, respectively. In a subsequent in vivo evaluation using various behavior pharmacological assays, an anxiolytic effect of these novel diphenylpyrazolinyl ureas was found in the elevated x-maze with an ED50 of 1.7 mg/kg. In the despair swimming test, a model for testing antidepressants, an ED50 of 0.69 mg/kg was determinated for urea 5e and the antidepressant effect had a magnitude comparable to desimipramine.
The coupling between receptor-mediated Ca2+ store release and the activation of "store-operated" Ca2+ entry channels is an important but so far poorly understood mechanism. The transient receptor potential (TRP) superfamily of channels contains several members that may serve the function of store-operated channels (SOCs). The 3,5-bis(trifluoromethyl)pyrazole derivative, BTP2, is a recently described inhibitor of SOC activity in T-lymphocytes. We compared its action on SOC activation in a number of cell types and evaluated its modification of three specific TRP channels, canonical transient receptor potential 3 (TRPC3), TRPC5, and TRPV6, to throw light on any link between SOC and TRP channel function. Using HEK293 cells, DT40 B cells, and A7r5 smooth muscle cells, BTP2 blocked store-operated Ca2+ entry within 10 min with an IC50 of 0.1-0.3 microM. Store-operated Ca2+ entry induced by Ca2+ pump blockade or in response to muscarinic or B cell receptor activation was similarly sensitive to BTP2. Using the T3-65 clonal HEK293 cell line stably expressing TRPC3 channels, TRPC3-mediated Sr2+ entry activated by muscarinic receptors was also blocked by BTP2 with an IC50 of <0.3 microM. Importantly, direct activation of TRPC3 channels by diacylglycerol was also blocked by BTP2 (IC50 approximately 0.3 microM). BTP2 still blocked TRPC3 in medium with N-methyl-D-glucamine-chloride replacing Na+, indicating BTP2 did not block divalent cation entry by depolarization induced by activating monovalent cation entry channels. Whereas whole-cell carbachol-induced TRPC3 current was blocked by 3 microM BTP2, single TRPC3 channel recordings revealed persistent short openings suggesting BTP2 reduces the open probability of the channel rather than its pore properties. TRPC5 channels transiently expressed in HEK293 cells were blocked by BTP2 in the same range as TRPC3. However, function of the highly Ca(2+)-selective TRPV6 channel, with many channel properties akin to SOCs, was entirely unaffected by BTP2. The results indicate a strong functional link between the operation of expressed TRPC channels and endogenous SOC activity.
2,5-Dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid) forms X-H.Y (X, Y = N or O) and C-H.Cl hydrogen bonds with pyrazole and imidazole to afford bis(pyrazolium) dichloroanilate and bis(imidazolium) dichloroanilate, (I) and (II), both 2C(3)H(5)N(2)(+).C(6)Cl(2)O(4)(2-), and imidazolium chloroanilate acetonitrile solvate, C(3)H(5)N(2)(+).C(6)HCl(2)O(4)(-).C(2)H(3)N, (III). Their crystal structures demonstrate three novel supramolecular architectures based on supramolecular synthons to build a ladder, (I), a two-dimensional network, (II), and a flat ribbon, (III).
In the neutral title complex, [Cu(C3H2O4)(C5H8N2)2(H2O)]*2H2O or [Cu(mal)(dmp)2(H2O)]*2H2O (mal is malonate and dmp is 3,5-dimethyl-1H-pyrazole), the Cu(II) ion, in a slightly distorted square-pyramidal geometry, is coordinated by two O atoms of the bidentate malonate, the O atom of the water ligand and two N atoms from the two 3,5-dimethylpyrazole ligands. The mean Cu-N bond length is 2.007 (6) A, longer than the Cu-O(mal) bonds [1.950 (5) A]. The apical position is occupied by a relatively strongly coordinated water molecule [Cu-O(water) 2.288 (5) A]. The crystal structure is characterized by the layer motif of a hydrogen-bonded network.
In the title compound, C(20)H(22)N(6), the molecules are linked into a chain of rings by N[bond]H...N [H...N 2.16 A, N...N 2.950 (3) A and N[bond]H...N 149 degrees] and C[bond]H...N [H...N 2.55 A, C...N 3.481 (3) A and C[bond]H...N 165 degrees ] hydrogen bonds, and these chains are linked into sheets by means of C[bond]H...pi(pyrazole) interactions.
The title compound, [Cu(4)Cl(6)O(C(12)H(14)N(2))(4)], is a new example of the well known [Cu(4)(mu(4)-O)(mu-X)(6)L(4)] class of complex (X(-) is Cl(-), Br(-) or I(-), and L is a monodentate ligand). The molecule has crystallographic C(2) symmetry, with two Cl(-) ions on each edge of a Cu(4) tetrahedron. Two of these, on opposite edges of the tetrahedron, accept intramolecular hydrogen bonds from two of the pyrazole N-H donors.
The trans-trans conformations adopted by the derivatized bis(bidentate) chelating N(4)-donor ligand 3,6-bis(pyrazol-1-yl)-4-[2-(4-thiamorpholino)ethanesulfanyl]pyridazine, C(16)H(19)N(7)S(2), and an intermediate in its formation, 3,6-dichloro-4-[2-(4-thiamorpholino)ethanesulfanyl]pyridazine, C(10)H(13)Cl(2)N(3)S(2), contrast with the cis-cis conformation found previously for 3,6-bis(thiophen-2-yl)pyridazine [Ackers, Blake, Hill & Hubberstey (2002). Acta Cryst. C58, o640-o641], which places all four heteroatoms on the same side of the molecule.
In the crystal structure of the title complex, [Co(C(6)H(8)N(3)S)(3)], the Co(III) atom is octahedrally coordinated by three monodeprotonated bidentate 3,5-dimethyl-1H-pyrazole-1-thiocarboxamide ligands with two thiocarboxamide N atoms in axial positions. The asymmetric unit contains two molecules (A and B) and these molecules are arranged in chains in an alternating fashion connected by N-H...S interactions.
In 2,8,8-trimethyl-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-one, C(13)H(15)N(3)O, (I), the heterobicyclic system is planar and exhibits peripheral ten pi-electron delocalization. In 3-tert-butyl-4',4'-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H- pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C(23)H(25)N(3)O(2), (II), the pyrazole ring exhibits marked bond fixation, while the reduced pyridine ring adopts a half-chair conformation. Molecules of (I) are linked into centrosymmetric R(2)(2)(6) dimers by a single C-H.N hydrogen bond [H.N = 2.50 A, C.N = 3.3397 (17) A and C-H.N = 148 degrees ], and these dimers are linked into chains by a single pi-pi stacking interaction. In (II), the combined action of one N-H.O hydrogen bond [H.O = 2.40 A, N.O = 3.2248 (15) A and N-H.O = 157 degrees ] and one C-H.O hydrogen bond [H.O = 2.48 A, C.O = 3.407 (2) A and C-H.O = 164 degrees ] links the molecules into sheets built from alternating centrosymmetric R(2)(2)(12) and R(6)(6)(48) rings; there is a weak C-H.N interaction [H.N = 2.60 A, C.N = 3.5149 (18) A and C-H.N = 154 degrees ] between molecules in adjacent sheets.