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1.
Int J Biol Macromol ; 278(Pt 1): 134654, 2024 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-39128748

RESUMEN

In this paper the effects on the interaction of highly positively charged substitution-inert platinum polynuclear complexes (SI-PPCs) with negatively charged DNA and heparin are examined and compared by theoretical chemistry methods. Electrostatic and hydrogen bonding interactions contribute to the overall effects on the biomolecule. Root Mean Square (RMS) deviation, Solvent Accessible Surface, RMS fluctuation, and interaction analysis all confirm similar effects on both biomolecules, dictated predominantly by the total positive charge and total number of hydrogen bonds formed. Especially, changes in structural parameters suggesting condensation and reduction of available surface area will reduce or prevent normal protein recognition and may thus potentially inhibit biological mechanisms related to apoptosis (DNA) or reduced vascularization viability (HEP). Thermodynamic analyses supported these findings with favourable interaction energies. The comparison of DNA and heparin confirms the general intersectionality between the two biomolecules and confirms the intrinsic dual-nature function of this chemotype. The distinction between the two-limiting mode of actions (HS or DNA-centred) could reflect an intriguing balance between extracellular (GAG) and intracellular (DNA) binding and affinities. The results underline the need to fully understand GAG-small molecule interactions and their contribution to drug pharmacology and related therapeutic modalities. This report contributes to that understanding.

2.
Angew Chem Int Ed Engl ; : e202411635, 2024 Jul 04.
Artículo en Inglés | MEDLINE | ID: mdl-38963679

RESUMEN

Over the years, polynuclear cyclic or torus complexes have attracted increasing interest due to their unique metal topologies and properties. However, the isolation of polynuclear cyclic organometallic complexes is extremely challenging due to their inherent reactivity, which stems from the labile and reactive metal-carbon bonds. In this study, the pyrazine ligand undergoes a radical-radical cross-coupling reaction leading to the formation of a decanuclear [(Cp*)20Dy10(L1)10]·12(C7H8) (1; where L1 = anion of 2-prop-2-enyl-2H-pyrazine) complex, where all DyIII metal centers are bridged by the anionic L1 ligand. Amongst the family of polynuclear Ln organometallic complexes bearing CpR2Lnx units, 1 features the highest nuclearity obtained to date. In-depth computational studies were conducted to elucidate the proposed reaction mechanism and formation of L1, while probing of the magnetic properties of 1, revealed slow magnetic relaxation upon application of a static dc field.

3.
J Inorg Biochem ; 256: 112545, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38581803

RESUMEN

Trinuclear ruthenium(II) polypyridyl complexes anchored to benzimidazole-triazine / trisamine scaffolds were investigated as photosensitizers for photodynamic therapy. The trinuclear complexes were noted to produce a significant amount of singlet oxygen in both DMF and aqueous media, are photostable and show appreciable emission quantum yields (ɸem). In our experimental setting, despite the moderate phototoxic activity in the HeLa cervical cancer cell line, the phototoxic indices (PI) of the trinuclear complexes are superior relative to the PIs of a clinically approved photosensitizer, Photofrin®, and the pro-drug 5-aminolevulinic acid (PI: >7 relative to PI: >1 and PI: 4.4 for 5-aminolevulinic acid and Photofrin®, respectively). Furthermore, the ruthenium complexes were noted to show appreciable long-term cytotoxicity upon light irradiation in HeLa cells in a concentration-dependent manner. Consequently, this long-term activity of the ruthenium(II) polypyridyl complexes embodies their ability to reduce the probability of the recurrence of cervical cancer. Taken together, this presents a strong motivation for the development of polymetallic complexes as anticancer agents.


Asunto(s)
Complejos de Coordinación , Fotoquimioterapia , Fármacos Fotosensibilizantes , Rutenio , Neoplasias del Cuello Uterino , Humanos , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/síntesis química , Células HeLa , Neoplasias del Cuello Uterino/tratamiento farmacológico , Neoplasias del Cuello Uterino/patología , Rutenio/química , Femenino , Complejos de Coordinación/farmacología , Complejos de Coordinación/química , Complejos de Coordinación/síntesis química , Fotoquimioterapia/métodos , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Piridinas/química , Piridinas/farmacología , Oxígeno Singlete/metabolismo
4.
Photochem Photobiol Sci ; 23(2): 315-327, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38261230

RESUMEN

Reaction of two equivalents of [Ln(dbm)3(H2O)] (Ln = Sm/Eu/Gd) with one equivalent of 4,4'-bipyridine (4,4'-bpy) led to the formation of rare polynuclear complexes of the type [Ln(dbm)3(4,4'-bpy)]n (dbm is the anion of 1,3-diphenyl-1,3-propanedione) instead of symmetrically bridged dinuclear complexes. The structure of the complexes has been established by the single crystal X-ray diffraction (SC-XRD) method and shows that the coordination sphere is composed of a LnO6N2 core (octacoordinated). Shape analysis further revealed that the geometry around Ln(III) is distorted square anti-prismatic with SHAPE value 0.738 and 25.719 for [Sm(dbm)3(4,4'-bpy)]n and [Eu(dbm)3(4,4'-bpy)]n, respectively. Photoluminescence (PL) properties of [Sm(dbm)3(4,4'-bpy)]n and [Eu(dbm)3(4,4'-bpy)]n are discussed in the solid-state and PMMA hybrid film (w/w 6%). By employing theoretical modelling in conjunction with the experimental PL data and crystal structure and an energy transfer (ET) mechanism for the sensitized PL of [Eu(dbm)3(4,4'-bpy)]n is proposed and discussed in detail. Finally, the role of each ligand in sensitized PL of [Eu(dbm)3(4,4'-bpy)]n is calculated and discussed by the chemical partitions of the radiative decay.Graphical abstract.

5.
Chemistry ; 29(71): e202302497, 2023 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-37733973

RESUMEN

Multinuclear, self-assembled lanthanide complexes present clear opportunities as sensors and imaging agents. Despite the widely acknowledged potential of this class of supramolecule, synthetic and characterization challenges continue to limit systematic studies into their self-assembly restricting the number and variety of lanthanide architectures reported relative to their transition metal counterparts. Here we present the first study evaluating the effect of ligand backbone symmetry on multinuclear lanthanide complex self-assembly. Replacement of a symmetric ethylene linker with an unsymmetric amide at the center of a homoditopic ligand governs formation of an unusual Ln6 L6 complex with coordinatively unsaturated metal centers. The choice of triflate as a counterion, and the effect of ionic radii are shown to be critical for formation of the Ln6 L6 complex. The atypical Ln6 L6 architecture is characterized using a combination of mass spectrometry, luminescence, DOSY NMR and EPR spectroscopy measurements. Luminescence experiments support clear differences between comparable Eu6 L6 and Eu2 L3 complexes, with relatively short luminescent lifetimes and low quantum yields observed for the Eu6 L6 structure indicative of non-radiative decay processes. Synthesis of the Gd6 L6 analogue allows three distinct Gd⋯Gd distance measurements to be extracted using homo-RIDME EPR experiments.

6.
Int J Mol Sci ; 24(17)2023 Aug 25.
Artículo en Inglés | MEDLINE | ID: mdl-37686030

RESUMEN

Synchronous electron diffraction/mass spectrometry was used to study the composition and structure of molecular forms existing in a saturated vapor of cobalt(II) oxopivalate at T = 410 K. It was found that monomeric complexes Co4O(piv)6 dominate in the vapor. The complex geometry possesses the C3 symmetry with bond lengths Co-Oc = 1.975(5) Å and Co-O = 1.963(5) Å, as well as bond angles Oc-Co-O = 111.8(3)°, Co-Oc-Co = 110.4(6)°, O-Co-O = 107.1(3)° in the central OcCo4 fragment and four OcCoO3 fragments. The presence of an open 3d shell for each Co atom leads to the possibility of the existence of electronic states of the Co4O(piv)6 complex with Multiplicities 1, 3, 5, 7, 9, 11, and 13. For them, the CASSCF and XMCQDPT2 calculations predict similar energies, identical shapes of active orbitals, and geometric parameters, the difference between which is comparable with the error of determination by the electron diffraction experiment. QTAIM and NBO analysis show that the Co-Oc and Co-O bonds can be attributed to ionic (or coordination) bonds with a significant contribution of the covalent component. The high volatility and simple vapor composition make it possible to recommend cobalt (II) oxopivalate as precursors in the preparation of oxide films or coatings in the CVD technologies. The features of the electronic and geometric structure of the Co4O(piv)6 complex allows for the conclude that only a very small change in energy is required for the transition from antiferromagnetically to ferromagnetically coupled Co atoms.


Asunto(s)
Cobalto , Electrónica , Electrones , Gases , Estructura Molecular
7.
Chemistry ; 29(37): e202300116, 2023 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-36924425

RESUMEN

Silver complexes bearing substituted terpyridine or tetra-2-pyridinylpyrazine ligands have been prepared and structurally characterised. The study of the anticancer properties of silver complexes with this type of ligands is scarce, despite the possibilities of combining the properties of the metal and the ability of the ligands for DNA binding. Here, the antiproliferative activity, stability, CT-DNA binding, and mechanism of cell death of these types of derivatives are studied. High cytotoxicity against different tumour cells was observed, and, more important, a great selectivity index has been detected between tumour cells and healthy lymphocytes T for some of these compounds. The CT-DNA interaction study has shown that these derivatives are able to interact with CT-DNA by moderate intercalation. Furthermore, cell death studies indicate that these derivatives promote the apoptosis by a mitochondrial pathway.


Asunto(s)
Antineoplásicos , Complejos de Coordinación , Neoplasias , Humanos , Relación Estructura-Actividad , Plata , Ligandos , Ensayos de Selección de Medicamentos Antitumorales , ADN/química , Antineoplásicos/farmacología , Antineoplásicos/química , Complejos de Coordinación/farmacología , Complejos de Coordinación/química , Línea Celular Tumoral
8.
Molecules ; 28(4)2023 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-36838816

RESUMEN

Carbon-based polynuclear clusters are designed and investigated for geometric, electronic, and nonlinear optical (NLO) properties at the CAM-B3LYP/6-311++G(d,p) level of theory. Significant binding energies per atom (ranging from -162.4 to -160.0 kcal mol-1) indicate excellent thermodynamic stabilities of these polynuclear clusters. The frontier molecular orbital (FMOs) analysis indicates excess electron nature of the clusters with low ionization potential, suggesting that they are alkali-like. The decreased energy gaps (EH-L) with increased alkali metals size revael the improved electrical conductivity (σ). The total density of state (TDOS) study reveals the alkali metals' size-dependent electronic and conductive properties. The significant first and second hyperpolarizabilities are observed up to 5.78 × 103 and 5.55 × 106 au, respectively. The ßo response shows dependence on the size of alkali metals. Furthermore, the absorption study shows transparency of these clusters in the deep-UV, and absorptions are observed at longer wavelengths (redshifted). The optical gaps from TD-DFT are considerably smaller than those of HOMO-LUMO gaps. The significant scattering hyperpolarizability (ßHRS) value (1.62 × 104) is calculated for the C3 cluster, where octupolar contribution to ßHRS is 92%. The dynamic first hyperpolarizability ß(ω) is more pronounced for the EOPE effect at 532 nm, whereas SHG has notable values for second hyperpolarizability γ(ω).


Asunto(s)
Carbono , Electrónica , Modelos Moleculares , Conformación Molecular , Termodinámica
9.
J Mol Struct ; 1278: 134857, 2023 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-36619309

RESUMEN

In this study, polynuclear Cu(II) complex (1), Mn(II) and Mn(III) complex (2) have been prepared with a Schiff base ligand derived from 2-Hydroxy-3-methoxybenzaldehyde with 2-amino-2-methyl-1-propanol. The compounds were characterized by elemental analysis, FT-IR, and UV-Vis spectroscopy. The molecular and crystal structures of (1-2) were determined by the single-crystal x-ray diffraction technique. It turned out that Cu(II) complex (1) forms an S4 -symmetrical tetrameric cage structure, with square-planar coordinated Cu and bridging O atoms at the vertexes of the approximate cube. In the crystal structure of 1, there are large channels along the c-axis, between the tetramers; the solvent- DMSO molecules, occupies these channels. In turn, the complex (2) creates a centrosymmetric trimeric structure, with three octahedrally coordinated Mn ions bridged by O atoms from ligand molecules and acetate ions. The electrochemical behavior studies of the complexes in DMSO displayed the electronic effects of the groups on the redox potential. The redox behavior of Schiff base (1) and (2) complexes included quasi -reversible and irreversible voltammograms, respectively. Intermolecular interactions in the solid states were studied by Hirshfeld surface analysis. These studies provide a comprehensive description of these inter-contact exchanges using an attractive graphical representation using Hirshfeld surfaces and fingerprint plots, along with enrichment ratios. Furthermore, assessment of the inhibitory effect against coronavirus (main protease SARS-CoV-2) was performed by a molecular docking study for both complexes (1 and 2). Both complexes showed a good affinity for CoV-2 for PDB protein ID: 6M03 and 6Y2F.

10.
Angew Chem Int Ed Engl ; 62(7): e202217456, 2023 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-36511854

RESUMEN

Lanthanide metal-organic frameworks (Ln-MOFs) are promising for luminescence detection of volatile organic compound (VOC) vapors, but usually suffer from the silent or quenched Ln3+ emission. Herein, we report a new dual-emissive Eu-MOF composed of the coordinatively unsaturated Eu9 clusters that afford abundant open metal sites to form a confined "binding pocket" to facilitate the preconcentration and recognition of VOCs. Single-crystal structural analyses reveal that specific analytes can replace the OH oscillators in the first coordination sphere of Eu3+ and form a unique hydrogen-bonding second-sphere adduct tying adjacent Eu9 clusters together to minimize their nonradiative vibrational decay. With the promoted Eu3+ luminescence, the MOF realizes real-time in situ visual sensing of THF vapor (<1 s) and shows a quantitative ratiometric response to the vapor pressure with a limit of detection down to 17.33 Pa. Also, it represents a top-performing ratiometric luminescent thermometer.

11.
J Environ Sci (China) ; 124: 823-834, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36182186

RESUMEN

Electrocoagulation (EC) has been widely used to treat the heavy metal wastewater in industry. A novel process of sinusoidal alternating current electrocoagulation (SACC) is adopted to remove Ni2+ in wastewater in this study. The morphology of precipitates and the distribution of the main functional iron configurations were investigated. Ferron timed complex spectroscopy can identify the monomeric iron configurations [Fe(a)], oligomeric iron configurations [Fe(b)] and polymeric iron configurations [Fe(c)]. The optimal operating conditions of SACC process were determined through single-factor experiments. The maximum Ni2+ removal efficiency [Re(Ni2+)] was achieved under the conditions of pH0=7, current density (j) = 7 A/m2, electrolysis time (t) = 25 min, c0(Ni2+) = 100 mg/L. At pH=7, the proportion of Fe(b) and Fe(c) in the system was 50.4 at.% and 23.1 at.%, respectively. In the SACC process, Fe(b) and Fe(c) are the main iron configurations in solution, while Fe(c) are the vast majority of the iron configurations in the direct current electrocoagulation (DCC) process. Re(Ni2+) is 99.56% for SACC and 98.75% for DCC under the same optimum conditions, respectively. The precipitates produced by SACC have a high proportion of Fe(b) configurations with spherical α-FeOOH and γ-FeOOH structures which contain abundant hydroxyl groups. Moreover, it is demonstrated that Fe(b) has better adsorption capacity than Fe(c) through adsorption experiments of methyl orange (MO) dye. Fe(a) configurations in the homogeneous solution had no effect on the removal of nickel.


Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , Purificación del Agua , Electrocoagulación , Electrodos , Concentración de Iones de Hidrógeno , Hierro/química , Níquel , Aguas Residuales , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos
12.
Molecules ; 27(23)2022 Dec 02.
Artículo en Inglés | MEDLINE | ID: mdl-36500578

RESUMEN

Two isostructural pairs of supramolecular iodoantimonate(III) and iodobismuthate(III) complexes with I2 units "trapped" in solid state via halogen bonding-Cat3[[M2I9](I2)} (Cat = tetramethylammonium and 1-methylpyridinium, M = Sb(III) and Bi(III)) were prepared. For all compounds, values of optical band gaps were determined, together with thermal stability; the complexes were additionally characterized by Raman spectroscopy.


Asunto(s)
Antimonio , Bismuto , Antimonio/química , Bismuto/química , Halógenos
13.
Molecules ; 27(23)2022 Dec 02.
Artículo en Inglés | MEDLINE | ID: mdl-36500581

RESUMEN

To understand how polyethyleneimine (PEI), as a ligand, affects structure and properties of the transition metals hexacyanoferrates (HCFs) immobilized in cross-linked PEI matrix, we have synthesized Cu(II), Zn(II), and Fe(III) HCFs via successive ion-exchange reactions with metal salts and K4[FeII(CN)6] or K3[FeIII(CN)6]. The structure and properties of the obtained materials in comparison with the crystalline HCF analogs were investigated with FT-IR, Mössbauer, and UV-Vis spectroscopy. Complete reduction of Fe(III) to Fe(II) by PEI in HCF(III) was confirmed. When synthesis was performed at pH favoring binding of precursor metal ions by PEI, cyano-bridged hybrids rather than polymer-HCFs composites were formed. Although the obtained hybrids did not demonstrate sorption activity toward cesium ions, known for crystalline HCFs, they are of interest for the other applications. SQUID measurements revealed a significant difference in magnetic properties of PEI-HCFs hybrids in comparison with crystalline HCFs. Due to the Fe(III) to Fe(II) reduction in HCF ions, Cu(II) and Fe(III) HCFs(III) lost the molecular magnets properties in PEI matrix, but magnetic ordering, including ferromagnet-antiferromagnet interactions, was observed in all hybrids over the broad temperature range.


Asunto(s)
Compuestos Férricos , Polietileneimina , Ligandos , Modelos Moleculares , Espectroscopía Infrarroja por Transformada de Fourier , Metales/química , Iones , Ferrocianuros
14.
Front Chem ; 10: 963203, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36247677

RESUMEN

Magnetocaloric effect (MCE) is one of the most promising features of molecular-based magnetic materials. We reported three Gd-based magnetic refrigerant materials, namely, Gd2(L)(NO3)(H2O)‧CH3CN‧H2O (1, H2L = (Z)-N-[(1E)-(2-hydroxy-3-methphenyl)methylidene]pyrazine-2-carbohydrazonic acid), {Gd6(L)6(CO3)2(CH3OH)2(H2O)3Cl}Cl‧4CH3CN (2), and Gd8(L)8(CO3)4(H2O)8‧2H2O (3). Complex 1 contains two GdIII ions linked by two η 2:η 1:η 1:η 1:µ 2-L2- ligands, which are seven-coordinated in a capped trigonal prism, and complex 2 possesses six GdIII ions, contributing to a triangular prism configuration. For complex 3, eight GdIII ions form a distorted cube arrangement. Moreover, the large values of magnetic entropy in the three complexes prove to be excellent candidates as cryogenic magnetic coolants.

15.
Angew Chem Int Ed Engl ; 61(34): e202206788, 2022 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-35712804

RESUMEN

The discrete multinuclear AgI -NHC complexes [Agn (1)n )](X)n ; (n=3 or 4, X=BF4 , PF6 ), synthesized from a bis-NHC ligand 1 and AgI ions via multiligand self-assembly, were observed to be in equilibrium between two forms (tri- and tetranuclear) in solution on the NMR timescale, which is unprecedented in CNHC -donor based chemistry. The existence of both the species was confirmed by various studies such as NMR (1 H, VT, 2D-DOSY) and ESI-MS analysis along with concentration studies. Importantly, replacing AgI with other coinage metals (AuI and CuI ) was found to alter the phenomenon entirely: a slow exchange from the tetra- to trinuclear species was noticed for the AuI complexes (4 a, b), whereas no such process was detected in case of the CuI complexes (5 a, b).

16.
Magn Reson Chem ; 60(9): 893-900, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-35712821

RESUMEN

A family of three- and four-coordinated silver(I) complexes of formulas [Ag(PPh3 )2 L], [Ag(PPh3 )L], and [AgL]n with N-thiophosphorylated thiourea and thioamide ligands of general formula RC(S)NHP(S)(OPri)2 [R = Ph, PhNH, iPrNH, tBuNH, NH2 ] have been studied by solid-state 109 Ag and 31 P CPMAS NMR spectroscopy. 109 Ag NMR spectra have provided valuable structural information about Ag coordination, which is in good accordance with the available crystal structure data. The data presented in this work represent a significant addition to the available 109 Ag chemical shifts and chemical shifts anisotropies. The silver chemical shift ranges for different P,S-environments and coordination state were discussed in detail. The 1 J(31 P-107/109 Ag) and 2 J(31 P-31 P) values were determined and analyzed.


Asunto(s)
Plata , Tiourea , Ligandos , Espectroscopía de Resonancia Magnética/métodos , Plata/química , Tioamidas , Tiourea/química
17.
Front Chem ; 10: 863408, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35529695

RESUMEN

Using DFT/(B3LYP/wB97XD/B2PLYPD) and OVGF electronic structure methods with flexible atomic orbital basis sets, we examined the series of polynuclear superhalogen anions matching the (BF3(BN) n F4n+1)- formula (for n = 1-10,13,18-20) containing alternately aligned boron and nitrogen central atoms decorated with fluorine ligands. It was found that the equilibrium structures of these anions correspond to fully extended chains (with each B and N central atom surrounded by four substituents arranged in a tetrahedral manner) and thus mimic the globally stable fully extended (all-trans) conformations of higher n-alkanes. The vertical electron detachment energies of the (BF3(BN) n F4n+1)- anions were found to exceed 8 eV in all cases and gradually increase with the increasing number of n. The approximate limiting value of vertical electron binding energy that could be achieved for such polynuclear superhalogen anions was estimated as equal to ca. 10.7 eV.

18.
Angew Chem Int Ed Engl ; 61(33): e202205385, 2022 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-35503751

RESUMEN

The ability to construct complex molecular architectures with precise control is critical for realizing molecule-based materials and functions. Using the assembly of a 60-metal complex of ErIII with histidine as an example, we demonstrate the rational assembly of otherwise synthetically elusive polynuclear lanthanide hydroxide clusters directed by the combined set of I- and CO3 2- as templates. We succeeded in the stepwise transformation starting from Er12 to Er60 by way of two key intermediates Er34 and Er48 . The Er12 , Er34 , and Er48 core motifs represent respectively 1/6, 1/2, and 3/4 of the complete sodalite cage of Er60 . This work, representing a rare example of rationally constructing high-nuclearity lanthanide clusters guided by judiciously chosen templates, is expected to stimulate more future efforts for the controllable synthesis of complex molecular or supramolecular architectures with unprecedented structural sophistication and possibly useful properties.

19.
Artículo en Inglés | MEDLINE | ID: mdl-35262454

RESUMEN

Polycyclic aromatic hydrocarbons (PAHs), the main component of petroleum, are a concern due to their environmental persistence, long-range transport, and potential toxic effects on animal, human health, and the environment. PAHs are considered persistent compounds and can be bioaccumulated in sediments and aquatic biota. Determining PAHs in animals and environmental samples consists of three steps: extraction, clean-up or purification, and analytical determination. The matrix complexity and the diversity of environmental contaminants, such as PAHs resulted in the development of numerous analytical techniques and protocols for the extraction of these components and analysis in several samples. This systematic review article seeks to relate the extraction and preparation methods of complex samples from aquatic animals and the two main detection techniques of PAHs. For the elaboration of the research, 67 articles published between 2011 and 2021 were sought, which specifically contemplated the isolation of aquatic extracts and detection and quantification techniques of PAHs.


Asunto(s)
Hidrocarburos Policíclicos Aromáticos , Animales , Cromatografía de Gases y Espectrometría de Masas , Hidrocarburos Policíclicos Aromáticos/análisis
20.
Chemistry ; 28(27): e202200769, 2022 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-35289461

RESUMEN

In comparison to mononuclear gold Lewis acid catalysts, digold complexes and dual-gold catalysis have illustrated a distinct and powerful potential for the activation of carbon-carbon multiple bonds. Herein, this concept is pushed further by designing novel tetranuclear gold(I) dicationic complexes structurally supported by strongly stabilizing constraint diphosphinoferrocenyl ligands and attractive closed-shell Au⋅⋅⋅Au aurophilic interactions. The use of a molecularly-defined tetranuclear dicationic aurophilic gold(I) precatalyst for the selectivity-challenging cycloisomerization of low-substituted 1,6-enynes favors the formation with high selectivity of strained azabicyclo[4.1.0]hept-4-enes - even in the complete absence of activating/orienting substituents on alkyne and olefin reactive functions. This selectivity is not achieved by the reported phosphine- and carbene-stabilized mono- and dinuclear cationic gold(I) complexes, including the ones formed from the same ligands. More importantly this selectivity differs also from nanoparticles and heterogeneous gold catalysts reported to date. DFT studies correlated to experimental mechanistic investigations support an unprecedented "cluster-like" reactivity from polynuclear cooperation at the origin of this peculiar selectivity where the aurophilic interactions preexist, and pre-organize, gold cluster reactive intermediates.

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