- Intermolecular binding modes in a novel [1 + 1] condensation 1 H -pyrazole azamacrocycle: A solution and solid state study with evidence for CO2 fixation
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The synthesis of a novel cyclophane (L1) consisting of a 1H-pyrazole moiety linked through methylene groups to a 1,5,9,13-tetraazadecane chain is described. As far as we know, this is one of the first reported syntheses of a [1 + 1] condensation 1H-pyrazole azamacrocyclic ligand. The crystal structures of the complexes [Cu2(H(H-1L1))(H-1L1)] (ClO4)3·3.75H2O (1) and ([Cu 2(H(H-1L1))0.5(H-1L1) 1.5]2(ClO4)3Br2·4. 2H2O (2) show that Cu2+ coordination leads to formation of 2:2 Cu2+:L dinuclear dimeric complexes in which the 1H-pyrazole units lose a proton behaving as bis(monodentate) bridging ligands. Unlike previously reported complexes of [2 + 2] pyrazole azamacrocycles, the pyrazolate units in 1 are pointing outward from the macrocyclic cavity to bind the Cu 2+ ions. Inner coordination with formation of 1:1 Cu2+:L complexes is however observed in [1 + 1] pyridine azamacrocycles as shown by the crystal structure here presented of the complex [CuL2](ClO4) 2 (3). Crystals of [Cu3(H-1L1) 2(CO3)(H2O)](ClO4) 2·8H2O (4) grown by evaporating aqueous solution at pH 9 containing Cu2+ and L1 in 3:2 molar ratio show the presence of a further Cu2+ coordinated to the two free amine groups found in structures 1 and 2. The metal ion fills its coordination sphere capturing atmospheric CO2 as a η1,η2-bidentate carbonate anion placed in the equatorial position and an axial water molecule. pH-metric data, UV-vis spectroscopic data, EPR measurements, and HR-ESI-MS data support that the outer coordination mode with formation of 2:2 dinuclear dimeric and 3:2 trinuclear complexes is preserved in aqueous solution.
- Belda, Raquel,Pitarch-Jarque, Javier,Soriano, Conxa,Llinares, Jose M.,Blasco, Salvador,Ferrando-Soria, Jesus,Garcia-Espana, Enrique
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- Efficient photochemical water oxidation by a dinuclear molecular ruthenium complex
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Herein is described the preparation of a dinuclear molecular Ru catalyst for H2O oxidation. The prepared catalyst mediates the photochemical oxidation of H2O with an efficiency comparable to state-of-the-art catalysts.
- Laine, Tanja M.,K?rk?s, Markus D.,Liao, Rong-Zhen,A?kermark, Torbj?rn,Lee, Bao-Lin,Karlsson, Erik A.,Siegbahn, Per E. M.,A?kermark, Bj?rn
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- PYRROLOBENZODIAZEPINE DIMER PRECURSOR AND LIGAND-LINKER CONJUGATE COMPOUND THEREOF
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The present invention relates to a pyrrolobenzodiazepine dimer prodrug and a ligand-linker conjugate compound thereof, a composition containing these, and therapeutic use thereof particularly as an anticancer drug. The stability of the compounds themselves and the stability thereof in plasma are excellent and the compounds are advantageous in terms of manifestation of toxicity, and thus the compounds are industrially useful in that it is possible to target proliferative diseases such as cancer, to perform a specific treatment, to maximize the drug efficacy, and to minimize the occurrence of side effects.
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Paragraph 0267; 0269
(2020/02/18)
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- Synthesis of 3- and 5-formyl-4-phenyl-1H-pyrazoles: Promising head units for the generation of asymmetric imine ligands and mixed metal polynuclear complexes
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Two synthetic methodologies are reported for the generation of 4-phenyl-1H-pyrazoles substituted at the 3- and/or 5-positions. Functionalisation of the 4-position of dimethyl-4-iodo-1-(tetrahydropyran-2-yl)- 3,5-pyrazolecarboxylate (10) to produce dimethyl-4-phenyl-1-(tetrahydropyran-2- yl)-3,5-pyrazolecarboxylate (14) was achieved by a C-C Suzuki-Miyaura cross coupling reaction in water. However, low yields for this reaction led us to develop a second methodology wherein functionalisation of N-(tetrahydropyran-2- yl)-4-phenylpyrazole (18), synthesised from inexpensive phenylacetic acid, with formyl or hydroxymethyl groups was achieved by lithiation methods. The resulting monoaldehydes, 4-phenyl-5-pyrazole carbaldehyde (20) and 5-formyl-3-(2′- tetrahydropyranyloxymethyl)-4-phenyl-1-(tetrahydropyran-2-yl)pyrazole (28), should facilitate access to new, asymmetric, imine ligands based on a 4-phenyl-1H-pyrazole moiety. This was proven by the successful synthesis of the heterometallic tetranuclear complex [FeII(NiIIL 2)3](BF4)2·solvents. Likewise, the alcohol isolated en route to 28, N-(tetrahydropyran-2-yl)-5- (hydroxymethyl)-4-phenylpyrazole (24), should facilitate access to new, asymmetric, amine ligands.
- Olguin, Juan,Brooker, Sally
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p. 1242 - 1253
(2011/08/03)
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- Synthesis and Protonation Behavior of 26-Membered Oxaaza and Polyaza Macrocycles Containing Two Heteroaromatic Units of 3,5-Disubstituted Pyrazole or 1-Benzylpyrazole. A Potentiometric and 1H and 13C NMR Study
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The synthesis and acid-base behavior of two series of 26-membered dioxatetraamine and hexaamine heterocyclophanes containing two nuclei of either pyrazole (4a and 6a) or 1-benzylpyrazole (4b and 6b), respectively, are reported. Dipodal (2 + 2) condensations of 3,5-pyrazoledicarbaldehyde 2a or its 1-benzyl derivative 2b with 1,5-diamino-3-oxapentane afford in both cases the stable Schiff bases 3a,b in 90% yield, which after reduction with NaBH4 gave 4a,b in 75% and 84% yield, respectively. Condensation of 2a with diethylenetriamine leads to a complex mixture containing imidazolidine isomers, which was reduced in situ to afford 6a in 30% yield. Condensation of 2b with the same amine gave the stable diimidazolidine derivative 5b, which after crystallization was isolated as a pure compound in 80% yield and fully identified from analytical and 1H and 13C NMR data as a constitutional isomer with both imidazolidine rings located at the side of the pyrazole closer to the benzylic substituents. Reduction of 5b with NaBH4 afforded the polyamine 6b in 86% yield. Protonation constants of 4a,b and 6a,b have been determined by potentiometric methods in the pH 2-11 range, and their protonation sequences were established by a 1H and 13C NMR study in D2O at variable pH. For each compound, the number of protonation constants equals the number of nitrogens in the side chains. In the pH range studied, the pyrazole rings are not involved in protonation or deprotonation processes.
- Aran, Vicente J.,Kumar, Manoj,Molina, Jose,Lamarque, Laurent,Navarro, Pilar,Garcia-Espana, Enrique,Ramirez, Jose A.,Luis, Santiago V.,Escuder, Beatriz
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p. 6135 - 6146
(2007/10/03)
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