Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 211
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Inorg Chem ; 59(18): 13078-13090, 2020 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-32902965

RESUMO

The new luminescent carbonyl compounds [Mn(Oxa-H)(CO)3Br] (1) and [Mn(Oxa-NMe2)(CO)3Br] (2) were synthesized and fully characterized. Complexes 1 and 2 showed CO release under blue light (λ453). Spectroscopic techniques and TD-DFT and SOC-TD-DFT calculations indicated that 1 and 2 release the Oxa-H and Oxa-NMe2 coligands in addition to the carbonyl ligands, increasing the luminescence during photoinduction.

2.
Chemistry ; 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32240560

RESUMO

The theoretical data for the half-lantern complexes [{Pt( C N ^ )(µ- S N ^ )}2 ] [1-3; C N ^ is cyclometalated 2-Ph-benzothiazole; S N ^ is 2-SH-pyridine (1), 2-SH-benzoxazole (2), 2-SH-tetrafluorobenzothiazole (3)] indicate that the Pt⋅⋅⋅Pt orbital interaction increases the nucleophilicity of the outer d z 2 orbitals to provide assembly with electrophilic species. Complexes 1-3 were co-crystallized with bifunctional halogen bonding (XB) donors to give adducts (1-3)2 ⋅(1,4-diiodotetrafluorobenzene) and infinite polymeric [1⋅1,1'-diiodoperfluorodiphenyl]n . X-ray crystallography revealed that the supramolecular assembly is achieved through (Aryl)I⋅⋅⋅d z 2 [PtII ] XBs between iodine σ-holes and lone pairs of the positively charged (PtII )2 centers acting as nucleophilic sites. The polymer includes a curved linear chain ⋅⋅⋅Pt2 ⋅⋅⋅I(areneF )I⋅⋅⋅Pt2 ⋅⋅⋅ involving XB between iodine atoms of the perfluoroarene linkers and (PtII )2 moieties. The 195 Pt NMR, UV/Vis, and CV studies indicate that XB is preserved in CH(D)2 Cl2 solutions.

3.
Dalton Trans ; 2020 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-32103214

RESUMO

Twenty clusters of the general formula [(µ-H)2Ru3(µ3-S)(CO)7(µ-P-P*)] (P-P* = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters. A catalytic mechanism involving an active Ru3 catalyst generated by CO loss from [(µ-H)2Ru3(µ3-S)(CO)7(µ-P-P*)] has been investigated by DFT calculations.

4.
Soft Matter ; 16(11): 2795-2802, 2020 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-32104828

RESUMO

Square planar platinum(ii) complexes are attractive building blocks for multifunctional soft materials due to their unique optoelectronic properties. However, for soft materials derived from synthetically simple discrete metal complexes, achieving a combination of optical properties, thermoresponsiveness and excellent mechanical properties is a major challenge. Here, we report the rapid self-recovery of luminescent metallogels derived from platinum(ii) complexes of perfluoroalkyl and alkyl derivatives of terpyridine ligands. Using single crystal X-ray diffraction studies, we show that the presence of synergistic platinum-platinum (PtPt) metallopolymerization and fluorine-fluorine (FF) interactions are the major driving forces in achieving hierarchical superstructures. The resulting bright red gels showed the presence of highly entangled three-dimensional networks and helical nanofibres with both (P and M) handedness. The gels recover up to 87% of their original storage modulus even after several cycles under oscillatory step-strain rheological measurements showing rapid self-healing. The luminescence properties, along with thermo- and mechanoresponsive gelation, provide the potential to utilize synthetically simple discrete complexes in advanced optical materials.

5.
Materials (Basel) ; 12(20)2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31618829

RESUMO

New Ag(I) coordination polymers, formulated as [Ag(µ-PTAH)(NO3)2]n (1) and [Ag(µ-PTA)(NO2)]n (2), were self-assembled as light- and air-stable microcrystalline solids and fully characterized by NMR and IR spectroscopy, electrospray ionization mass spectrometry (ESI-MS(±), elemental analysis, powder (PXRD) and single-crystal X-ray diffraction. Their crystal structures reveal resembling 1D metal-ligand chains that are driven by the 1,3,5-triaza-7-phospaadamantane (PTA) linkers and supported by terminal nitrate or nitrite ligands; these chains were classified within a 2C1 topological type. Additionally, the structure of 1 features a 1D→2D network extension through intermolecular hydrogen bonds, forming a two-dimensional hydrogen-bonded network with fes topology. Furthermore, both products 1 and 2 exhibit remarkable antimicrobial activity against different human pathogen bacteria (S. aureus, E. coli, and P. aeruginosa) and yeast (C. albicans), which is significantly superior to the activity of silver(I) nitrate as a reference topical antimicrobial.

6.
ACS Omega ; 4(16): 16891-16898, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31646235

RESUMO

Three-dimensionally printed solid but highly porous polyamide-12 (PA12) plate-like filters were used as selective adsorbents for capturing tetrachloroaurate from acidic solutions and leachates to prepare PA12-Au composite catalysts. The polyamide-adsorbed tetrachloroaurate can be readily reduced to gold nanoparticles by using sodium borohydride, ascorbic acid, hydrogen peroxide, UV light, or by heating. All reduction methods led to polyamide-anchored nanoparticles with an even size distribution and high dispersion. The particle sizes were somewhat dependent on the reduction method, but the average diameters were typically about 20 nm. Particle sizes were determined by using a combination of single-particle inductively coupled plasma mass spectrometry, helium ion microscopy, and powder X-ray diffraction. Dispersion of the particles was analyzed by scanning electron microscopy with energy-dispersive spectroscopy. Due to the high adsorption selectivity of polyamide-12 toward tetrachloroaurate, the three-dimensional-printed filters were first used as selective gold scavengers for the acidic leachate of electronicwaste (WEEE). The supported nanoparticles were then generated directly on the filter via a simple reduction step. These objects were used as catalysts for the reduction of 4-nitrophenol to 4-aminophenol. The described method provides a direct route from waste to catalysts. The selective laser sintering method can be used to customize the flow properties of the catalytically active filter object, which allows the optimization of the porous catalytic object to meet the requirements of catalytic processes.

7.
ACS Omega ; 4(7): 12012-12017, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31460313

RESUMO

Three-dimensional selective laser sintering printing was utilized to produce porous, solid objects, in which the catalytically active component, Pd/SiO2, is attached to an easily printable supporting polypropylene framework. Physical properties of the printed objects, such as porosity, were controlled by varying the printing parameters. Structural characterization of the objects was performed by helium ion microscopy, scanning electron microscopy, and X-ray tomography, and the catalytic performance of the objects was tested in the hydrogenation of styrene, cyclohexene, and phenylacetylene. The results show that the selective laser sintering process provides an alternative and effective way to produce highly active and easily reusable heterogeneous catalysts without significantly reducing the catalytic efficiency of the active Pd/SiO2 component. The ability to control the size, porosity, mechanical properties, flow properties, physical properties, and chemical properties of the catalyst objects opens up possibilities to optimize devices for different reaction environments including batch reactions and continuous flow systems.

8.
Acta Crystallogr E Crystallogr Commun ; 75(Pt 3): 358-361, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30867949

RESUMO

In the complex cation of the title compound, [Fe(C27H41N10O3)](PF6)2, the tripodal tris-{4-[1-(2-meth-oxy-eth-yl)imidazol-2-yl]-3-aza-but-3-en-yl}amine ligand is coordinated to an FeII ion through the nitro-gen atoms of three imidazole and three imino groups. The Fe atom exhibits a distorted octa-hedral geometry. In the crystal, l and d anti-podes are arranged in layers in the bc plane. Weak C⋯F and C-H⋯F/O contacts exist between the ligands of the complex cation and the PF6 - anions, generating a three-dimensional network. At 120 K, the FeII ion is in a low-spin state, with an average Fe-N bond distance of 1.970 (2) Å. On heating, the FeII ion converts to the high-spin state, as demonstrated by magnetic susceptibility measurements.

9.
Front Chem ; 7: 97, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30881952

RESUMO

The new di- and tetranuclear Fe(III) µ-oxido complexes [Fe4(µ-O)4(PTEBIA)4](CF3SO3)4(CH3CN)2] (1a), [Fe2(µ-O)Cl2(PTEBIA)2](CF3SO3)2 (1b), and [Fe2(µ-O)(HCOO)2(PTEBIA)2](ClO4)2 (MeOH) (2) were prepared from the sulfur-containing ligand (2-((2,4-dimethylphenyl)thio)-N,N-bis ((1-methyl-benzimidazol-2-yl)methyl)ethanamine (PTEBIA). The tetrairon complex 1a features four µ-oxido bridges, while in dinuclear 1b, the sulfur moiety of the ligand occupies one of the six coordination sites of each Fe(III) ion with a long Fe-S distance of 2.814(6) Å. In 2, two Fe(III) centers are bridged by one oxido and two formate units, the latter likely formed by methanol oxidation. Complexes 1a and 1b show broad sulfur-to-iron charge transfer bands around 400-430 nm at room temperature, consistent with mononuclear structures featuring Fe-S interactions. In contrast, acetonitrile solutions of 2 display a sulfur-to-iron charge transfer band only at low temperature (228 K) upon addition of H2O2/CH3COOH, with an absorption maximum at 410 nm. Homogeneous oxidative catalytic activity was observed for 1a and 1b using H2O2 as oxidant, but with low product selectivity. High valent iron-oxo intermediates could not be detected by UV-vis spectroscopy or ESI mass spectrometry. Rather, evidence suggest preferential ligand oxidation, in line with the relatively low selectivity and catalytic activity observed in the reactions.

10.
Dalton Trans ; 48(10): 3369-3379, 2019 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-30785137

RESUMO

Methylene bridged 2,2'-dipyridylamine (dpa) derivatives and their metal complexes possess outstanding properties due to their inherent structural flexibility. Synthesis of such complexes typically involves derivatization of dpa followed by coordination on metals, and may not always be very efficient. In this work, an alternative synthetic approach, involving the derivatization step after - rather than prior to - coordination of dpa on metal center, is proposed and applied to synthesis of a number of platinum(ii) complexes with substituted benzyldi(2-pyridyl)amines. Comparison with the more conventional synthetic route reveals greater efficiency and versatility of the proposed approach. The obtained complexes are not luminescent in solution at room temperature, but display blue phosphorescence emission (ca. 415 nm) with the lifetimes of µs order in glassy matrix at 77 K, with additional green (ca. 485 nm) and relatively long living (τ = 3.7 ms) emission in the case of iodine substituted derivative.

11.
Soft Matter ; 15(3): 442-451, 2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30570631

RESUMO

Herein we report silver(i) directed infinite coordination polymer network (ICPN) induced self-assembly of low molecular weight organic ligands leading to metallogelation. Structurally simple ligands are derived from 3-aminopyridine and 4-aminopyridine conjugates which are composed of either pyridine or 2,2'-bipyridine cores. The cation specific gelation was found to be independent of the counter anion, leading to highly entangled fibrillar networks facilitating the immobilization of solvent molecules. Rheological studies revealed that the elastic storage modulus (G') of a given gelator molecule is counter anion dependent. The metallogels derived from ligands containing a bipyridine core displayed higher G' values than those with a pyridine core. Furthermore, using single crystal X-ray diffraction studies and 1H-15N two-dimensional (2D) correlation NMR spectroscopy, we show that the tetracoordination of silver ions enables simultaneous coordination polymerization and metallosupramolecular cross-linking. The resulting metallogels show spontaneous, in situ nanoparticle (d < 2-3 nm) formation without any additional reducing agents. The silver nanoparticle formation was followed using spectroscopic studies, and the self-assembled fibrillar networks were imaged using transmission electron microscopy (TEM) imaging.


Assuntos
4-Aminopiridina/química , Géis/química , Nanopartículas Metálicas/química , Prata/química , Reagentes para Ligações Cruzadas/química , Polimerização , Reologia
12.
Chempluschem ; 84(2): 222-225, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31950695

RESUMO

Metal-organic frameworks (MOFs) have raised a lot of interest, especially as adsorbing materials, because of their unique and well-defined pore structures. One of the main challenges in the utilization of MOFs is their crystalline and powdery nature, which makes their use inconvenient in practice. Three-dimensional printing has been suggested as a potential solution to overcome this problem. We used selective laser sintering (SLS) to print highly porous flow-through filters containing the MOF copper(II) benzene-1,3,5-tricarboxylate (HKUST-1). These filters were printed simply by mixing HKUST-1 with an easily printable nylon-12 polymer matrix. By using the SLS, powdery particles were fused together in such a way that the structure of the printed solid material resembles the structure of a powder bed. The MOF additive is firmly attached only on the surface of partially fused polymer particles and therefore remains accessible to fluids passing through the filter. Powder X-ray analysis of the printed object confirmed that printing did not have any negative impact on the structure of the MOF. CO2 -adsorption studies also showed that the activity of the MOF was not affected by the printing process. SLS offers a straightforward and easy way to fabricate tailor-made MOF-containing filters for practical applications.

13.
Chemistry ; 24(32): 8071-8075, 2018 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-29663537

RESUMO

Herein we report a multi-component reaction approach for the development of a new class of hydrogelators based on the OxoTriphenylHexanOate (OTHO) backbone. A focused library of OTHOs has been synthesized and their hydrogelation features evaluated. The two most potent hydrogelators were studied by rheology revealing different stiffness, appearances and thixotropic behavior of the gels. The new gelators showcase the versatility of the OTHO backbone as a platform for the design of functionalized hydrogels with tunable gel properties.

14.
J Am Chem Soc ; 140(8): 2957-2970, 2018 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-29397708

RESUMO

With the goal to produce molecules with high electron accepting capacity and low reorganization energy upon gaining one or more electrons, a synthesis procedure leading to the formation of a B-N(aromatic) bond in a cluster has been developed. The research was focused on the development of a molecular structure able to accept and release a specific number of electrons without decomposing or change in its structural arrangement. The synthetic procedure consists of a parallel decomposition reaction to generate a reactive electrophile and a synthesis reaction to generate the B-N(aromatic) bond. This procedure has paved the way to produce the metallacarboranylviologen [M(C2B9H11)(C2B9H10)-NC5H4-C5H4N-M'(C2B9H11)(C2B9H10)] (M = M' = Co, Fe and M = Co and M' = Fe) and semi(metallacarboranyl)viologen [3,3'-M(8-(NC5H4-C5H4N-1,2-C2B9H10)(1',2'-C2B9H11)] (M = Co, Fe) electron cumulative molecules. These molecules are able to accept up to five electrons and to donate one in single electron steps at accessible potentials and in a reversible way. By targeted synthesis and corresponding electrochemical tests each electron transfer (ET) step has been assigned to specific fragments of the molecules. The molecules have been carefully characterized, and the electronic communication between both metal centers (when this situation applies) has been definitely observed through the coplanarity of both pyridine fragments. The structural characteristics of these molecules imply a low reorganization energy that is a necessary requirement for low energy ET processes. This makes them electronically comparable to fullerenes, but on their side, they have a wide range of possible solvents. The ET from one molecule to another has been clearly demonstrated as well as their self-organizing capacity. We consider that these molecules, thanks to their easy synthesis, ET, self-organizing capacity, wide range of solubility, and easy processability, can find important application in any area where ET is paramount.

16.
ACS Omega ; 3(9): 11558-11561, 2018 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31459255

RESUMO

In the current paper, a series of nonlinear optical (NLO) active devices was prepared by utilizing stereolithographic three-dimensional printing technique. Microcrystalline NLO active component, urea, or potassium dihydrogen phosphate was dispersed in a simple photopolymerizable polyacrylate-based resin and used as the printing material to fabricate highly efficient transparent NLO lenses. The nonlinear activity of the printed lenses was confirmed by second-harmonic generation measurements using a femtosecond laser-pumped optical parametric amplifier operating at a wavelength of 1195 nm. The three-dimensional printing provides a simple method to utilize a range of NLO active compounds without tedious crystal growing and processing steps. Furthermore, introducing NLO additives in the printing material provides an easy and cost-efficient way to manufacture lenses with NLO functionality.

17.
Eur J Med Chem ; 143: 503-514, 2018 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-29202411

RESUMO

Three new compounds have been synthesized and completely characterized by analytical and spectroscopic techniques. The new bipyridine-perfluorinated ligand L1 and the new organometallic complex [Ru(η5-MeCp)(PPh3)2Cl] (Ru1) crystalize in the centrosymmetric triclinic space group P1¯. Analysis of the phenotypic effects induced by both organometallic complexes Ru1 and [Ru(η5-MeCp)(PPh3)(L1)][CF3SO3] (Ru2), on human colorectal cancer cells (SW480 and RKO) survival, showed that Ru2 has a potent anti-proliferative activity, 4-6 times higher than cisplatin, and induce apoptosis in these cells. Data obtained in a noncancerous cell line derived from normal colon epithelial cells (NCM460) revealed an intrinsic selectivity of Ru2 for malignant cells at low concentrations, showing the high potential of this compound as a selective anticancer agent.


Assuntos
Antineoplásicos/farmacologia , Neoplasias Colorretais/tratamento farmacológico , Cicloparafinas/farmacologia , Compostos Organometálicos/farmacologia , Piridinas/farmacologia , Rutênio/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Neoplasias Colorretais/patologia , Cicloparafinas/química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Ligantes , Estrutura Molecular , Compostos Organometálicos/síntese química , Compostos Organometálicos/química , Piridinas/química , Rutênio/química , Relação Estrutura-Atividade
18.
Beilstein J Org Chem ; 13: 2364-2371, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29181116

RESUMO

A study exploring the chemical behavior of some dihydroxylated ß-amino ester stereo- and regioisomers, derived from unsaturated cyclic ß-amino acids is described. The nucleophilic fluorinations involving hydroxy-fluorine exchange of some highly functionalized alicyclic diol derivatives have been carried out in view of selective fluorination, investigating substrate dependence, neighboring group assistance and chemodifferentiation.

19.
Inorg Chem ; 56(12): 7038-7047, 2017 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-28557422

RESUMO

The synthesis, crystal structure, magnetic, calorimetric, and Mössbauer studies of a series of new Hofmann-type spin crossover (SCO) metal-organic frameworks (MOFs) is reported. The new SCO-MOFs arise from self-assembly of FeII, bis(4-pyridyl)butadiyne (bpb), and [Ag(CN)2]- or [MII(CN)4]2- (MII = Ni, Pd). Interpenetration of four identical 3D networks with α-Po topology are obtained for {Fe(bpb)[AgI(CN)2]2} due to the length of the rod-like bismonodentate bpb and [Ag(CN)2]- ligands. The four networks are tightly packed and organized in two subsets orthogonally interpenetrated, while the networks in each subset display parallel interpenetration. This nonporous material undergoes a very incomplete SCO, which is rationalized from its intricate structure. In contrast, the single network Hofmann-type MOFs {Fe(bpb)[MII(CN)4]}·nGuest (MII = Ni, Pd) feature enhanced porosity and display complete one-step or two-step cooperative SCO behaviors when the pores are filled with two molecules of nitrobenzene or naphthalene that interact strongly with the pyridyl and cyano moieties of the bpb ligands via π-π stacking. The lack of these guest molecules favors stabilization of the high-spin state in the whole range of temperatures. However, application of hydrostatic pressure induces one- and two-step SCO.

20.
Inorg Chem ; 56(10): 5502-5505, 2017 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-28440634

RESUMO

The first examples of coordination polymers of manganese(II) and a nickel(II) complex with a purely inorganic carboranylphosphinate ligand are reported, together with its exhaustive characterization. X-ray analysis revealed 1D polymeric chains with carboranylphosphinate ligands bridging two manganese(II) centers. The reactivity of polymer 1 with water and Lewis bases has also been studied.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA