Synthesis,Crystal Structure,Fluorescent and Antioxidation Properties of Cerium(III) and Europium(III) Complexes with Bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine

Two aliphatic ether Schiff base lanthanide complexes (Ln = Eu, Ce) with bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine (Bod), were synthesized and characterized by physicochemical and spectroscopic methods. [Eu(Bod)(NO₃)₃] ( 1 ) is a discrete mononuclear species and [Ce(Bod)(NO₃)₃DMF]_∞ ( 2 ) exhibits an inorganic coordination polymer. In the two complexes, the metal ions both are ten‐coordinated and the geometric structure around the Ln^III atom can be described as distorted hexadecahedron. Under excitation at room temperature, the red shift in the fluorescence band of the ligand in the complexes compared with that of the free ligand can be attributed to coordination of the rare earth ions to the ligand. Moreover, the antioxidant activities of the two complexes were investigated. The results demonstrated that the complexes have better scavenging activity than both the ligand and the usual antioxidants on the hydroxyl and superoxide radicals.     

A Selenium‐Nitrogen Chain with Selenium in Different Oxidation States

The reaction of tBuNH₂ with a mixture of SeCl₂ and SeOCl₂ in a 6:2:1 molar ratio produces the novel selenium‐nitrogen chain ClSeN(tBu)Se(O)Cl ( 4 ), in which the selenium atoms are in two different oxidation states, Se^II and Se^IV. The crystal structure of 4 is compared with that of the related Se^II/Se^II system ClSeN(tBu)SeCl ( 1 ) and differences are attributed to hyperconjugative effects. The energetics of the formation of 4 via two different routes are elucidated by PBE0/def2‐TZVPP calculations.     

CsSc3F6[SeO3]2: A New Rare‐Earth Metal(III) Fluoride Oxoselenate(IV) With Sections Of The ReO3‐Type Structure

A new representative of rare‐earth metal(III) fluoride oxoselenates(IV) derivatized with alkali metals could be synthesized via solid‐state reactions. Colorless single crystals of CsSc₃F₆[SeO₃]₂ were obtained through the reaction of Sc₂O₃, ScF₃, and SeO₂ (molar ratio 1:1:3) with CsBr as reactant and fluxing agent. For this purpose, corundum crucibles embedded as liners into evacuated silica ampoules were applied as containers for these reactions at 700 °C for seven days. The new quintenary compound crystallizes in the trigonal space group P3m1 with a = 565.34(4) and c = 1069.87(8) pm (c/a = 1.892) for Z = 1. The crystal structure of CsSc₃F₆[SeO₃]₂ contains two crystallographically different Sc³⁺ cations. Each (Sc1)³⁺ is surrounded by six fluoride anions as octahedron, while the octahedra about (Sc2)³⁺ are formed by three fluoride anions and three oxygen atoms from three terminal [SeO₃]^2– anions. The [(Sc1)F₆]^3– octahedra link via common F^– vertices to six fac‐[(Sc2)F₃O₃]^6– octahedra forming ²_∞{[Sc₃F₆O₆]^9–} layers parallel to (001). These layers are separated by oxygen‐coordinated Cs⁺ cations (C.N. = 12), arranging for the charge compensation, while Se⁴⁺ cations within the layers surrounded by three oxygen atoms as ψ¹‐tetrahedral [SeO₃]^2– units complete the structure. EDX measurements confirmed the composition of the title compound and single‐crystal Raman studies showed the typical vibrational modes of isolated [SeO₃]^2– anions with ideal C_3v symmetry.     

A Potential Method Using Ge{iPrNC[N(SiMe3)2]NiPr}2, (Et3Si)2Te and Anhydrous Hydrazine for Germanium Tellurides

A germanium(II)‐guanidine derivative of formula Ge{iPrNC[N(SiMe₃)₂]NiPr}₂ ( 1 ) was synthesized and characterized by ¹H NMR, ¹³C NMR, elemental analysis, and X‐ray diffraction method. Thermal property was also studied to identify its thermal stability and volatility. More importantly, compound 1 was synthesized to develop a new method for germanium tellurides, where anhydrous hydrazine was introduced to prompt the activity of germanium(II) guanidines (or derivatives) towards (Et₃Si)₂Te. Solution reaction of compound 1 , (Et₃Si)₂Te, and anhydrous hydrazine was investigated to pre‐identify the feasibility of this combination for ALD process. The EDS data of the black precipitate from this reaction verified the potential of this method to manufacture germanium tellurides.     

A EuIII‐MOF with Bis(2‐carboxyethyl)isocyanurate for Luminescence Sensing of Fe3+ and SCN– Ions

The water‐stable 3D lanthanide‐organic framework (Ln‐MOF) {[Eu(bci)(H₂O)] · 2H₂O}_n ( 1 ) [H₂bci = bis(2‐carboxyethyl)isocyanurate] was synthesized under hydrothermal conditions. Compound 1 ‐ Eu exhibits a 3D open‐framework connected by Eu–(μ‐O)₂–Eu chains and bci ligands. Meanwhile, 1 ‐ Eu exhibits highly efficient luminescent sensing for environmentally relevant Fe³⁺ and SCN^– ions through luminescence quenching. These results indicated that it could be utilized as a multi‐responsive luminescence sensor.     

A Chromium(III)‐Superoxo Complex as a Three‐Electron Oxidant with a Large Tunneling Effect in Multi‐Electron Oxidation of NADH Analogues

Metal‐superoxo species are involved in a variety of enzymatic oxidation reactions, and multi‐electron oxidation of substrates is frequently observed in those enzymatic reactions. A Cr^III‐superoxo complex, [Cr^III(O₂)(TMC)(Cl)]⁺ ( 1 ; TMC=1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane), is described that acts as a novel three‐electron oxidant in the oxidation of dihydronicotinamide adenine dinucleotide (NADH) analogues. In the reactions of 1 with NADH analogues, a Cr^IV‐oxo complex, [Cr^IV(O)(TMC)(Cl)]⁺ ( 2 ), is formed by a heterolytic O−O bond cleavage of a putative Cr^II‐hydroperoxo complex, [Cr^II(OOH)(TMC)(Cl)], which is generated by hydride transfer from NADH analogues to 1 . The comparison of the reactivity of NADH analogues with 1 and p ‐chloranil (Cl₄Q) indicates that oxidation of NADH analogues by 1 proceeds by proton‐coupled electron transfer with a very large tunneling effect (for example, with a kinetic isotope effect of 470 at 233 K), followed by rapid electron transfer.     

HACA's Heritage: A Free‐Radical Pathway to Phenanthrene in Circumstellar Envelopes of Asymptotic Giant Branch Stars

The hydrogen‐abstraction/acetylene‐addition (HACA) mechanism has been central for the last decades in attempting to rationalize the formation of polycyclic aromatic hydrocarbons (PAHs) as detected in carbonaceous meteorites such as in Murchison. Nevertheless, the basic reaction mechanisms leading to the formation of even the simplest tricyclic PAHs like anthracene and phenanthrene are still elusive. Here, by exploring the previously unknown chemistry of the ortho ‐biphenylyl radical with acetylene, we deliver compelling evidence on the efficient synthesis of phenanthrene in carbon‐rich circumstellar environments. However, the lack of formation of the anthracene isomer implies that HACA alone cannot be responsible for the formation of PAHs in extreme environments. Considering the overall picture, alternative pathways such as vinylacetylene‐mediated reactions are required to play a crucial role in the synthesis of complex PAHs in circumstellar envelopes of dying carbon‐rich stars.     

Creep life evaluation of aluminum conductor composite core utilized in high voltage electric transmission

The creep life of aluminum conductor composite core (ACCC) utilized in high voltage electric transmission was investigated using an experimental method based on the equivalence relationship. First, the time-temperature-stress equivalence relationship was developed using the time-temperature and the time-stress equivalence relationships. Then, tensile creep experiments were conducted under different temperatures and different stress levels to obtain the strain-time curves of the ACCC. Finally, the creep strain master curve was obtained using the experimental data based on the time-temperature-stress equivalence relationship, allowing prediction of ACCC creep life. The results will play an important role in evaluation of the long-term characteristics of the ACCC for engineering applications.     

Improved separation and size characterization of gold nanoparticles through a novel capillary zone electrophoresis method using poly(sodium4‐styrenesulfonate) as stabiliser and a stepwise field strength gradient

A novel capillary zone electrophoresis (CZE) method was developed for an improved separation and size characterization of pristine gold nanoparticles (AuNP) using uncoated fused‐silica capillaries with UV‐Vis detection at 520 nm. To avoid colloid aggregation and/or adsorption during runs, poly(sodium 4‐styrenesulfonate) (PSS) was added (1%, w/v) in the running buffer (CAPS 10 mM, pH 11). This polyelectrolyte conferred an enhanced stabilization to AuNP, both steric and electrostatic, exalting at the same time their differences in electrophoretic mobility. Resolution was further and successfully improved through a stepwise field strength gradient by the application of 25 kV for the first 5 min and then 10 kV. Migration times varied linearly with particles diameters showing relative standard deviations better than 1% for daily experiments and 3% for interday experiments. A comparison with the size distribution obtained by transmission electron microscopy (TEM) allowed assessing that the electrophoretic profile can reasonably be considered as representative of the effective size heterogeneity of each colloid. Finally, the practical utility of the proposed method was demonstrated by measuring the core diameter of a gold colloid sample produced by chemical synthesis which was in good agreement with the value obtained by TEM measurements.     

Poly(acrylamidoglycolic acid) nanocomposite hydrogels reinforced with cellulose nanocrystals for pH-sensitive controlled release of diclofenac sodium

In this study, a non-cytotoxic and pH-sensitive poly(acrylamidoglycolic acid) based nanocomposite (PAGA-NC) hydrogels reinforced with cellulose nanocrystals (CNCs) was synthesized using redox free radical polymerization. The successful formation and crystalline behaviour of PAGA-NC hydrogels was verified by fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses. The results showed that morphological, rheological and mechanical properties of the PAGA-NC hydrogels were strongly influenced by the CNCs content. Moreover, swelling properties were investigated, and the results suggested that they behaved as pH sensitive manner. The in vitro MTT assay showed that the PAGA-NC hydrogels are cytocompatibile to NIH-3T3 fibroblast cells. In addition, diclofenac sodium (DCF) model drug was successfully encapsulated into these PAGA-NC hydrogels via equilibrium swelling method. The in vitro release of DCF from PAGA-NC hydrogels was retained at pH 1.2 and maximum release was observed at 7.4, revealing as potential candidates for controlled release carriers for oral drug delivery applications.