Dalton Transactions最新文献

The first Yb complexes comprising a quinoline-2-carboxylate (quinaldinate, Q⁻) ligand, namely 1D-polymeric [Yb(acac)₂(Q)]_n (1, acac⁻ is the acetylacetonate (pentane-2,4-dionate) anion) and mononuclear [Yb(acac)₂(Q)(Phen)] (2, Phen is 1,10-phenanthroline), are reported. The bifunctionality of both complexes as field-induced single-molecule magnets (SMMs) and near IR luminophores has been revealed. The SMM properties of 1 and 2 have been discussed in terms of the geometry and composition of the coordination environment. Also, 1 is the first example of 1D-polymeric SMMs with the capped octahedral surrounding of Yb³⁺. The photoluminescence quantum yields (PLQYs) of 1 and 2 are 2 and 4%, respectively. The origins of this difference are discussed. Surprisingly, the PLQY value of 2 is high for compounds comprising a lot of C–H vibrational quenchers, being the highest one for reliably characterized Yb β-diketonate complexes, and surpassing those for complexes with a broad range of anionic ligands. In this respect, the role of the Phen ligand is to tune the coordination mode of Q⁻ thereby decreasing the energy of coordinating C–O oscillators rather than to act as a typical antenna ligand. These results can give rise to an alternative route to elaborate efficient Yb-based luminophores via the substitution of the β-diketonate ligands controlled by the introduction of appropriate neutral ligands.

Dioxaphosphabicyclo[2.2.2]octanes (L1–L4) have been prepared in a one-pot reaction from tris(hydroxymethyl)phosphine and various α,β-unsaturated ketones. The non-volatile phosphines oxidise very slowly in air. They possess highly upfield ³¹P chemical shifts (−59 to −70 ppm), small cone angles (121–140°) and a similar electronic parameter to PPh₃. Reaction of L1 with [Rh(acac)(CO)₂] gave the complex [Rh(acac)(CO)(L1)] with a ν_(CO) of 1981.5 cm⁻¹, whereas reaction L1 with [Rh(CO)₂Cl]₂ gave [Rh(CO)(L1)₂Cl] with a ν_(CO) of 1979.9 cm⁻¹, remarkably similar to the CO stretching frequencies reported for analogous PPh₃ complexes. The cage phosphines were explored as ligands in rhodium catalysed hydroformylation of 1-octene. All of the ligands gave a linear selectivity to n-nonanal of 68%, regardless of the substituents. However the ligand substituents had a significant effect on the catalyst activity, with increased steric bulk around the coordination environment giving a three-fold increase in aldehyde yield. The phosphines undergo ligand subsitution with [Pd(MeCN)₂Cl₂] forming square planar trans-[Pd(L)₂Cl₂] complexes. Subsequent reduction with hydrazine furnishes homoleptic tetravalent [Pd(L1)₄] which was applied as a catalyst in Suzuki–Miyaura couplings, furnishing the C–C coupled products in moderate yields.

A joint structural and spectroscopic study of simple bis-cyclometataled rhodium(III) and iridium(III) complexes with 2-phenylpyridine and aromatic β-diketones (dibenzoylmethane, benzoylacetone, benzoyltrifluoroacetone, and 2-thenoyltrifluoroacetone) reveals an interplay between the solid-state emission efficiency and crystal packing peculiarities of the complexes. Although the prepared rhodium(III) cyclometalates are isostructural with iridium(III) analogues, different types of π–π interactions are responsible for the aggregation-induced emission (AIE) of the complexes depending on the metal ion. For iridium(III) complexes, pyridyl–pyridyl contacts are essential for AIE because they lower the energy of the emissive metal-to-ligand charge transfer state below that of the non-emissive state located at the ancillary ligand. Enabled by phenyl–pyridyl interactions partially blocking the population of non-emissive d–d states, solid-state phosphorescence enhancement is successfully achieved in a rhodium(III) complex with ancillary benzoyltrifluoroacetone, which is the first example of a rhodium complex exhibiting AIE.

A tridentate ligand LH₃ ((2-hydroxy-3-methoxybenzylidene)-2-(hydroxyimino)propanehydrazide) comprising o-vanillin, hydrazone and oxime donor groups has been employed to prepare a series of tetranuclear Ln(III) complexes. The reaction of ligand LH₃ with Ln(NO₃)₃ [Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er] in MeOH yielded Ln₄(LH)₆(MeOH)₂ (Ln = Sm(1), Eu(2), Gd(3), Tb(4), Ho (6) and Er (7))] whereas the corresponding reaction with Dy(NO₃)₃ afforded Dy₄(LH)₄(LH₂)₂(OH)₂ (5). All complexes were characterized by various analytical techniques including single crystal X-ray diffraction, IR spectroscopy, UV-Vis spectroscopy, and elemental analysis. To investigate the potential of these lanthanide complexes for wound healing applications, their effects on fibroblast viability, migration, and M2 macrophage polarization were evaluated. The cytotoxicity assessment revealed that complexes 2(Eu), 4(Tb), 5(Dy), and 7(Er) significantly enhanced fibroblast viability compared to the negative control (NC). In vitro wound healing assay demonstrated that complexes 2(Eu) and 7(Eu) substantially promoted fibroblast migration compared to the NC. Moreover, complex 2(Eu) exhibited significant anti-inflammatory effects by reducing the phagocytic ability of lipopolysaccharide (LPS)-stimulated macrophage cells and attenuating nitric oxide (NO) production. In conclusion, among the series of complexes tested, complex 2(Eu) displayed the most potent anti-inflammatory effect on macrophage cells, while simultaneously promoting fibroblast viability and migration. This unique combination of properties renders complex 2 (Eu) highly promising for wound healing applications.

The process of water photo-electrolysis possesses the capability to generate sustainable and renewable hydrogen fuels, consequently addressing the challenge of the irregularity of solar energy. Thus, developing highly-efficient and low-cost electrocatalysts for the use in contemporary renewable energy devices is critical. Herein, we report the fabrication of a novel BaCeFe_x−yBi_xO₆ nanocrystalline material through a one-step solvothermal route using a post-annealing process at 500 °C. The synthesized material was investigated for its light-induced electrochemical HER and OER activities in alkaline media and the results revealed that the as-prepared BaCeFe_x−yBi_xO₆-500 °C exhibited an excellent OER activity with an overpotential of 100 mV to achieve a current density of 10 mA cm⁻², thus outperforming the IrO₂ electrocatalyst. Besides its excellent water oxidation performance, the catalyst also demonstrated an admirable HER activity comparable to that of the Pt/C catalyst, indicating that the higher temperature treatment plays a significant role in achieving the maximum performance of the developed electrocatalyst. This work provides insights into the enhancement of light-induced OER and HER activities of bismuth oxides for a wide range of catalytic applications.

Designing an effective photoactive heterojunction having dual benefits towards photoenergy conversion and pollutant adsorption is regarded as an affordable, green method for eliminating tetracycline (TC) from wastewater. In this regard, a series of BiOBr@NU-1000 (BNU-X, X = 1, 2 and 3) heterojunction photocatalysts are constructed. BNU-X preserves the original skeleton structure of the parent NU-1000, and its high porosity and specific surface area enable superior TC adsorption. At the same time, BNU-X is an effective Z-scheme photocatalyst that improves light trapping, promotes photoelectron–hole separation, and shows excellent photocatalytic degradation efficiency towards TC with the value of the photodegradation kinetic rate constant k being 2.2 and 24.8 times those of NU-1000 and BiOBr, respectively. The significant increase in the photocatalytic activity is ascribed to the construction of an efficient Z-scheme photocatalyst, which promotes the formation of superoxide radicals (˙O₂⁻) and singlet oxygen (¹O₂) as the main oxidative species in the oxidation system. This research has the advantage of possibilities for the development of porous Z-scheme photocatalysts based on photoactive MOF materials and inorganic semiconductors for the self-purification and photodegradation of organic contaminants.

New 1,2-azolylamidino complexes fac-[RuCl(DMSO)₃(NHC(R)az*-κ²N,N)]OTf [R = Me (2), Ph (3); az* = pz (pyrazolyl, a), indz (indazolyl, b)] are synthesized via chloride abstraction from their corresponding precursors cis,fac-[RuCl₂(DMSO)₃(az*H)] (1) after subsequent base-catalyzed coupling of the appropriate nitrile with the 1,2-azole previously coordinated. All the compounds are characterized by ¹H NMR, ¹³C NMR and IR spectroscopy. Those derived from MeCN are also characterized by X-ray diffraction. Electrochemical studies showed several reduction waves in the range of −1.5 to −3 V. The electrochemical behavior in CO₂ media is consistent with CO₂ electrocatalytic reduction. The catalytic activity expressed as [i_cat(CO₂)/i_p(Ar)] ranged from 1.7 to 3.7 for the 1,2-azolylamidino complexes at voltages of ca. −2.7 to −3 V vs. ferrocene/ferrocenium. Controlled potential electrolysis showed rapid decomposition of the Ru catalysts. Photocatalytic CO₂ reduction experiments using compounds 1b, 2b and 3b carried out in a CO₂-saturated MeCN/TEOA (4 : 1 v/v) solution containing a mixture of the catalyst and [Ru(bipy)₃]²⁺ as the photosensitizer under continuous irradiation (light intensity of 150 mW cm⁻² at 25 °C, λ > 300 nm) show that compounds 1b, 2b and 3b allowed CO₂ reduction catalysis, producing CO and trace amounts of formate. The combined turnover number for the production of formate and CO is ca. 100 after 8 h and follows the order 1b < 2b ≈ 3b.

The energy transfer of Ce³⁺–Eu²⁺ can often greatly increase the luminescence efficiency and expand the scope of application. In this study, blue to cyan color-tunable phosphors BaCa₁₃Mg₂(SiO₄)₈:Ce³⁺,Eu²⁺ were prepared. BaCa₁₃Mg₂(SiO₄)₈:Eu²⁺ cyan phosphors have limited applications in WLEDs because of their disadvantages, including the inadequate luminescence performance and imperfect matching of UV chips. Therefore, Ce³⁺ ions were used as sensitizers to enhance the optical performance of Eu²⁺ ions. The energy transfer efficiency between Ce³⁺ and Eu²⁺ in the BaCa₁₃Mg₂(SiO₄)₈ host was calculated to be 96.7%, and the incorporation of Ce³⁺ ions boosted the integrated intensity and quantum efficiency of the emission spectrum by approximately 80% and 20%, respectively. At 140 °C, the integral emission intensities could still keep at 81.5% of the initial integral intensities at 25 °C. The Ce³⁺, Eu²⁺ co-doped cyan phosphor-based WLED lamp could produce outstanding warm white light with CIE coordinates of (0.3722, 0.3222), demonstrating the enormous potential for WLED applications.

The construction and development of metal–organic nanotubes (MONTs) with nanoscale interior channel diameters for potential applications is of great interest. An angular nitrogen-rich ligand, 3,6-bis(2-ethylimidazole)-2-methylpyrimidine (beim-CH₃), was designed to construct MONTs by coupling with the V-shaped carboxylate ligands of benzophenone 4,4′-dicarboxylic acid (H₂bpndc) and 4,4′-oxybisbenzoic acid (H₂obba). Two new MONTs were synthesized and named NCD-166 ([Zn(bpndc)(beim-CH₃)]·H₂O) and NCD-167 ([Zn(obba)(beim-CH₃)]·H₂O), and they were isostructural and have almost identical tube inner diameters of approximately 1.76 nm. Benefiting from the abundantly exposed nitrogen and oxygen atoms in their tube walls and open nanoporous channels, they display superior adsorption capacities for Eu³⁺ (150.90 mg g⁻¹) and high adsorption selectivity (>96%) in the low-concentration solutions. Additionally, it was revealed that the adsorption effect of ether oxygen on rare earth elements was significantly better than that of carbonyl oxygen. The adsorption isotherm conformed to the Langmuir model and the adsorption kinetics obeyed the pseudo-second-order model. These results clearly indicate that such novel MONTs are favorable sorbents for REEs.

A photoactive two-dimensional coordination polymer (2D CP) [Zn₂(4-spy)₂(bdc)₂]_n (1) [4-spy = 4-styrylpyridine and H₂bdc = 1,4-benzendicarboxylic acid] undergoes a photochemical [2 + 2] cycloaddition reaction upon UV irradiation. Interestingly, the crystals of 1 show different photomechanical effects, such as jumping, swelling, and splitting, during UV irradiation. In addition, the CP was employed for conductivity measurements before and after UV irradiation via current density–voltage characteristics and impedance spectroscopy, which suggest that they are semiconducting in nature and can be used as Schottky diodes. Thus, this work demonstrates the potential dual applications of a 2D CP based on photosalient and conductivity properties.