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The catalytic potential of a large series of easily available metal carbamates (based on thirteen different non-precious metal elements) was explored for the first time in the coupling reaction between 2-aryl-aziridines and carbon dioxide, working under solventless and ambient conditions and using tetraalkylammonium halides as co-catalysts. The straightforward synthesis of novel [NbCl3(O2CNEt2)2], NbCl, and [NbBr3(O2CNEt2)2], NbBr, is reported. The niobium complex NbCl, in combination with NBu4I, emerged as the best catalyst of the overall series to convert aziridines with small N-alkyl substituents into the corresponding 5-aryl-oxazolidin-2-ones. [ABSTRACT FROM AUTHOR]

The simple and cost-effective compound [Ag(O2CNEt2)], in combination with PPh3, works as an effective catalytic precursor in the carboxylation of propargyl alcohols at ambient temperature and atmospheric CO2 pressure, and in most cases under solventless conditions. The silver carbamate revealed a better performance than commercial silver oxide, Ag2O, and allowed to obtain a series of α-alkylidene cyclic carbonates in high yields. [ABSTRACT FROM AUTHOR]

Mononuclear RuII complex [RuCl(κ3N‐tpm)(κ2N‐bptz)]Cl, [1]Cl [tpm=tris(1‐ pyrazolyl)methane; bptz=3,6‐di(2‐pyridyl)‐1,2,4,5‐tetrazine], and dinuclear complexes [RuCl(κ3N‐tpm)(μ‐κ2N:κ2N‐bptz)Ru(κ2N‐bipy)2][PF6]3, [3][PF6]3, [RuCl(η6‐p‐cymene)(μ‐κ2N:κ2N‐dpp)Ru(κ2N‐bipy)2][PF6]2, [4][PF6]2, and [RuCl(η6‐p‐cymene)(μ‐κ2N:κ2N‐dpp)Ru(κ2N‐biqn)2][PF6]3, [5][PF6]3 [dpp=2,3‐bis(2′‐pyridyl)‐pyrazine; bipy=2,2′‐bipyridine; biqn=2,2′‐quinoline], incorporating both potentially catalytic and photosensitive subunits, were synthesized and characterized by means of elemental analysis, mass spectrometry, and spectroscopic methods. The molecular structures of the new compounds were also investigated and compared by means of DFT calculations. The absorption spectra of all the compounds are dominated by metal‐to‐ligand charge‐transfer bands in the visible (which in most cases largely extend over the red portion of the spectrum) and ligand‐centered bands in the UV region. The oxidation behavior is based on metal‐centered RuII to RuIII oxidation processes, which in phosphate buffer solution are followed by a catalytic water oxidation wave for [1]Cl and [3][PF6]3. For these compounds, the mechanism of water oxidation is proposed to consist in water nucleophilic attack, according to chemical experiments with Ce(IV) salts, so demonstrating for the first time that the bptz ligand can be profitably used to build ruthenium(II) complexes with catalytic properties. On the contrary, no catalytic process is observed for 4 and 5, most likely due to the high positive potential for RuII oxidation induced by the presence of the p‐cymene moiety. [ABSTRACT FROM AUTHOR]

Research has been conducted on the octanuclear aggregates. The preparation of these complexes carried out via the controlled hydrolysis of the metal carbamate precursors is described.

A 2D CuNi metal–organic framework (MOF) named CuxNi3−x(HHTP)2 was synthesized with 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) as the linker and was used as a sensitive scaffold to adsorb aptamer strands for the electrochemical detection of living C6 glioma cells and one of their biomarkers, epidermal growth factor receptor (EGFR). Different from conventional MOFs, the CuxNi3−x(HHTP)2 MOF comprises long-range delocalized electrons, a graphene-analog nanostructure, multiple metal states (Cu0/Cu+/Cu2+ and Ni2+/Ni3+), and abundant oxygen vacancies. With these features, the CuxNi3−x(HHTP)2 MOF anchored a large amount of C6 cell-targeted aptamer strands via coordination among metal centers, oligonucleotides, π–π stacking, and van der Waals force. The CuxNi3−x(HHTP)2-based cytosensor showed a low limit of detection (LOD) of 21 cells mL−1 toward C6 glioma cells within a wide range from 50 cells mL−1 to 1 × 105 cells mL−1. Moreover, the proposed aptasensor displayed high selectivity, good stability, acceptable reproducibility, and a low LOD of 0.72 fg mL−1 for detecting EGFR with the concentration ranging from 1 fg mL−1 to 1 ng mL−1. The aptasensor based on the CuxNi3−x(HHTP)2 MOF exhibited superior sensing performance over those based on its monometallic analogues such as Cu3(HHTP)2 MOF and Ni3(HHTP)2 MOF. Hence, this sensing strategy based on a bimetallic semiconducting MOF shows great potential for cancer diagnosis. [ABSTRACT FROM AUTHOR]

The development of sustainable synthetic routes to access valuable oxazolidinones via CO2 fixation is an active research area, and the aziridine/carbon dioxide coupling has aroused a considerable interest. This reaction features a high activation barrier and thus requires a catalytic system, and may present some other critical issues. Here, the straightforward gram‐scale synthesis of a series of 5‐aryl‐2‐oxazolidinones was developed at ambient temperature and atmospheric CO2 pressure, in the absence of any catalyst/co‐catalyst. The key to this innovative procedure consists in the direct transfer of the pre‐formed amine/CO2 adduct (carbamate) to common aziridine precursors (dimethylsulfonium salts), replacing the classical sequential addition of amine (intermediate isolation of aziridine) and then CO2. The reaction mechanism was investigated by NMR spectroscopy and DFT calculations applied to model cases. [ABSTRACT FROM AUTHOR]

This paper aims to make a socioeconomic analysis over rural settlements in the extreme south of Bahia and in Pontal do Paranapanema in São Paulo state. Its emphasis is on cassava agrobiodiversity. Semi-structured interviews were conducted with fifteen farmers in ten settlements in Bahia and eleven farmers in seven settlements in São Paulo. Those regions socioeconomic levels are among the lowest in their states, with major vulnerability in Bahia. About 60% of farmers's children live in the settlement, two thirds of them work on agricultural activities. Composed mainly by elderly population, settlements in Bahia represent most of cassava diversity, whose production provides to the artisanal flour production flour. The cultural dynamics over the flour production activities in the settlements constitute a key element in the region's agrobiodiversity maintenance. The Pontal's cassava production on the other hand, answers to the demand of industrial starch outside the settlements, which causes the growing of few varieties that answer to the industrial standards. The Bahia settlements' agroecological perspective has been fundamental to its agrobiodiversity enhancement while the industrial agriculture perspective endorsed in São Paulo's region weakens the agricultural diversity as well as its sociocultural structures associated with the agrobiodiversity maintenance. [ABSTRACT FROM AUTHOR]

Five‐ and six‐coordinated zinc(II) complexes, [Zn(QR)2(H2O)] (1–2) and [Zn(QR)2(L)] (3–8) {HQR = 4‐R(C=O)‐5‐pyrazolones in general, in detail HQC17, R = –(CH2)16CH3, HQCy, R = –C6H11; L = bipy, tmeda or en} have been synthesized and characterized by IR, 1H and 13C NMR, UV/Visible spectroscopy, elemental analysis, TGA and ESI mass spectrometry. The square pyramidal complex [Zn(QC17)2(H2O)] (1) has been structurally characterized, together with a trans octahedral [Zn(QCy)2(EtOH)2] (2b) species obtained by recrystallization of [Zn(QCy)2(H2O)] (2) from ethanol. Additionally, in both complexes [Zn(QCy)2(bipy)] (4) and [Zn(QC17)2(tmeda)] (5) structurally characterized by single crystal X ray diffraction, the same amount of Δ and Λ enantiomers are present, with the only difference related to the mutual disposition of the different type of the QR coordinated oxygen atoms. The cytotoxicity of the complexes [Zn(QCy)2(H2O)] (2), [Zn(QCy)2(bipy)] (4) and [Zn(QCy)2(en)] (8) has been evaluated in vitro against MCF‐7 human breast cancer cell line in a biohybrid membrane system. Results revealed that zinc complexes possess antiproliferative activity inducing apoptosis by activation of caspase‐3 and p‐JNK. [ABSTRACT FROM AUTHOR]

Two‐step functionalization of 4‐diphenylphosphino benzoic acid with biotin afforded 2‐(biotinyloxy)ethyl 4‐(diphenylphosphanyl)benzoate (LP), that was subsequently used to synthesize the Ru(II) arene complexes [RuCl2(η6‐p‐cymene)(LP)] (1), [Ru(C2O4)(η6‐p‐cymene)(LP)] (2) and [Ru(curc)(η6‐p‐cymene)(LP)]NO3 ([3]NO3), the latter incorporating curcumin (curcH) as an additional bioactive fragment. [Ru(curc)(η6‐p‐cymene)(PPh3)]NO3 ([4]NO3) was also prepared as a reference compound. Compounds 2 and [3]NO3 exhibited excellent stability in water/DMSO solution while being slowly activated in the cell culture medium over 72 hours. Together with LP, they were therefore assessed for their antiproliferative activity towards a panel of cancer cell lines, with different levels of biotin transporter expression. The apparent affinity of the compounds towards avidin varies, and their antiproliferative activity does not correlate with biotin transporter expression, although it is systematically enhanced when biotin‐free cell culture medium is used. [ABSTRACT FROM AUTHOR]

The reaction of pyrrolidine with a series of cationic diiron cyclopentadienyl complexes containing a bridging vinyliminium ligand gives access to piano stool monoiron complexes based on a five-membered metallacycle that includes a vinyl-aminoalkylidene moiety, in moderate to high yields. The resulting metallacyclic motif (aminoalkylidene-ferracyclopentenone) is unique in organometallic chemistry and is partially preconstructed on the dinuclear frame. The monoiron products were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy, and in a number of cases by X-ray diffraction and cyclic voltammetry. They are robust in aqueous solutions and generally unreactive towards alkylating agents in organic solvents. However, a cationic derivative was prepared in high yield by methylation of a 2-pyridyl group. The cytotoxicity of both neutral and ionic complexes was assessed on cancerous (A2780 and A280cisR) and non-cancerous (HEK293) cell lines, revealing the influence of local structural modifications on the antiproliferative activity and the selectivity of the compounds. [ABSTRACT FROM AUTHOR]