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1.
Chemistry ; 2020 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-32427376

RESUMO

Cooperation between two different metals plays a crucial role in many synergistic catalytic reactions such as the Sonogashira C-C cross-coupling reaction, where an interaction between the Pd and Cu centers is proposed in the transmetallation step. Although several heterobimetallic Pd/Cu complexes were proposed as structural models of the active species in Sonogashira coupling, the detailed understanding of the metal-metal cooperation in transmetallation is still lacking in current systems. In this work, we report a stepwise and systematic approach to building heteromultimetallic Pd/Cu assemblies as a tool to study metal-metal cooperativity. We obtained fully characterized Pd/Cu multimetallic assemblies that show reactivity in alkyne activation, formation of catalytically relevant aryl/acetylide species, and C-C elimination, serving as functional models for Sonogashira reaction intermediates. The combined experimental and DFT studies highlight the importance of ligand-controlled coordination geometry, metal-metal distances and dynamics of the multimetallic assembly for transmetallation step.

2.
Chem Commun (Camb) ; 56(1): 50-53, 2020 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-31764935

RESUMO

Dynamic CuI-based mechanophores used as cross-linkers in polybutylacrylates enable highly sensitive detection of mechanical stress even at small strain (<50%) and stress (<0.1 MPa) values via reversible changes in luminescence intensity. Such sensitivity is superior to previously reported systems based on classical organic mechanophores and it allows for direct visualization of mechanical stress by imaging methods.

3.
Chem Commun (Camb) ; 55(76): 11350-11353, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31463509

RESUMO

'Hangman-type' PNP pincer ligands and their associated Ru complexes undergo sp2-sp3 C-C bond cleavage and subsequent C-C formation processes to form a new, one carbon unit longer backbone motif. DFT and mechanistic studies suggest a mechanism dependent upon arm pyridine coordination and ligand sterics.

4.
Chem Asian J ; 14(17): 2979-2987, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31298502

RESUMO

New nickel-based complexes of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with BF4 - counterion or halide co-ligands were synthesized in THF and MeCN. The nickel(I) complexes were obtained by using two approaches: 1) electrochemical reduction of the corresponding nickel(II) precursors; and 2) a chemical comproportionation reaction. The structural features and redox properties of these complexes were investigated by using single-crystal X-ray diffraction (XRD), cyclic voltammetry (CV), and electron paramagnetic resonance (EPR) and UV/Vis spectroscopy. The influence of temperature and solvent on the structure of the nickel(I) complexes was studied in detail, and an uncommon reversible solvent-induced monomer/dimer transformation was observed. In the case of the fluoride complex, the unpaired electron was found to be localized on the dpp-bian ligand, whereas all of the other nickel complexes contained neutral dpp-bian moieties.

5.
Inorg Chem ; 58(12): 7698-7704, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31144500

RESUMO

A series of novel charged disilver(I) complexes with pyridyl-containing phospholanes was synthesized. These complexes were characterized using a range of spectroscopic techniques and single-crystal and powder X-ray diffraction. The complexes demonstrate solid-state near-infrared (NIR) luminescence (765-902 nm) that is unique for dinuclear AgI complexes. Combined spectroscopic/quantum chemical analysis suggests that the NIR luminescence of complexes 4-6 in the solid state is mainly due to crystal packing effects.

6.
Chem Commun (Camb) ; 55(22): 3282-3285, 2019 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-30810134

RESUMO

Single and double dearomatization of pyridine rings was observed in MnI complexes with an N2S2 pyridinophane ligand via deprotonation of one or two CH2 arms, respectively. In contrast to other N,S-donor pincer-like systems, the dearomatized (N2S2)Mn species were found to be stable, with the dearomatization being reversible.

7.
Inorg Chem ; 58(2): 1048-1057, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30601648

RESUMO

The unique L2Cu6I6 complexes containing two Cu3I3 units have been obtained via reaction of 1,5-diaza-3,7-diphosphacyclooctanes bearing ethylpyridyl substituents at phosphorus atoms with an excess of copper iodide. The structure of one of the complexes was confirmed by X-ray diffraction. It was shown that the complexes can exist in two crystalline phases with different parameters of the unit cell, which were detected by the PXRD data analyses. The solvent-free crystalline phases of the complexes display rare solid-state white emission at room temperature, which is observed due to the presence of two broad bands in the emission spectra with maxima at 464 and 610 nm. Quantum chemical computations show that the high-energy band has 3(M+X)LCT origin, whereas the low-energy band is interpreted as 3CC. The quantum yields of white luminescence of complexes reach 15-20%.

8.
Inorg Chem ; 57(16): 10009-10027, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30052030

RESUMO

The macrocyclic ligand conformational behavior in solution, solid-state structures and the photophysical properties of copper(I) cationic and neutral mononuclear complexes supported by tetradentate N, N'-dialkyl-2,11-diaza[3.3](2,6)-pyridinophane ligands RN4 (R = H, Me, iBu, secBu, neoPent, iPr, Ts) were investigated in detail. Steric properties of the alkyl group at the axial amine in the RN4 ligand were found to strongly affect the conformational preferences and dynamic behavior in solution. Several types of conformational exchange processes were revealed by variable-temperature NMR and 2D exchange spectroscopy, including degenerative exchange in a pseudotetrahedral species as well as exchange between two isomers with different conformers of tri- and tetracoordinate RN4 ligands. These exchange processes are slower for the complexes containing bulky alkyl groups at the amine compared to less sterically demanding analogues. A clear correlation is also observed between the steric bulk of the alkyl substituents and the photoluminescent properties of the derived complexes, with less dynamic complexes bearing bulkier alkyl substituents exhibiting higher absolute photoluminescence quantum yield (PLQY) in solution and the solid state: PLQY in solution increases in the order Me < neoPent < iBu < secBu ≈ iPr < tBu. The electrochemical properties of the cationic complexes [(RN4)CuI(MeCN)]X (X = BF4, PF6) were also dependent on the steric properties of the amine substituent.

9.
Bioorg Med Chem Lett ; 28(13): 2302-2313, 2018 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-29803731

RESUMO

A series of inhibitors of the soluble epoxide hydrolase (sEH) containing one or two thiourea groups has been developed. Inhibition potency of the described compounds ranges from 50 µM to 7.2 nM. 1,7-(Heptamethylene)bis[(adamant-1-yl)thiourea] (6f) was found to be the most potent sEH inhibitor, among the thioureas tested. The inhibitory activity of the thioureas against the human sEH is closer to the value of activity against rat sEH rather than murine sEH. While being less active, thioureas are up to 7-fold more soluble than ureas, which makes them more bioavailable and thus promising as sEH inhibitors.


Assuntos
Adamantano/análogos & derivados , Adamantano/farmacologia , Inibidores Enzimáticos/farmacologia , Epóxido Hidrolases/antagonistas & inibidores , Tioureia/análogos & derivados , Tioureia/farmacologia , Adamantano/síntese química , Animais , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Humanos , Camundongos , Modelos Químicos , Simulação de Acoplamento Molecular , Teoria Quântica , Ratos , Solubilidade , Tioureia/síntese química
10.
Angew Chem Int Ed Engl ; 56(51): 16267-16271, 2017 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-29105241

RESUMO

Reversible stepwise chain growth in linear CuI assemblies can be achieved by using the dynamic, unsymmetric naphthyridinone-based ligand scaffolds L1 and L2. With the same ligand scaffolds, the length of the linear copper chain can be varied from two to three and four copper atoms, and the nuclearity of the complex is easily controlled by the stepwise addition of a CuI precursor to gradually increase the chain length, or by the reductive removal of Cu atoms to decrease the chain length. This represents a rare example of a stepwise controlled chain growth in extended metal atom chains (EMACs). All complexes are formed with excellent selectivity, and the mutual transformations of the complexes of different nuclearity were found to be fast and reversible. These unusual rearrangements of metal chains of different nuclearities were achieved by a stepwise "sliding" movement of the naphthyridinone bridging fragment along the metal chain.

11.
J Pharm Sci ; 103(10): 3176-82, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25091705

RESUMO

The solubility of 3-(2-methoxyphenoxy)-propane-1,2-diol, the well-known chiral drug guaifenesin 1, in water has been investigated by means of polythermal and isothermal approaches. It was found that the solubilities of racemic and enantiomeric diols rac- and (R)-1 depend strongly on temperature. The ternary phase diagram of the guaifenesin enantiomers in water in the temperature range between 10°C and 40°C was constructed. Clear evidence was obtained that rac-1 crystallizes as a stable conglomerate. The Meyerhoffer coefficient for the guaifenesin-water system is more than two and strongly depends on temperature. Neither crystalline hydrates nor polymorphs were detected within the range of conditions covered. Metastable zone width data with regard to primary nucleation were also collected for rac-1 and (R)-1. On the basis of the knowledge acquired, the resolution of racemic guaifenesin by preferential crystallization from solution could be realized successfully.


Assuntos
Expectorantes/química , Guaifenesina/química , Cristalização , Difração de Pó , Solubilidade , Estereoisomerismo , Água/química
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