1,721,165 research outputs found
Il bipolarismo conflittuale. Il regime politico della Seconda Repubblica.
No full textSi tratta di un contributo che affronta il tema della forma di governo. I due autori analizzano il funzionamento della forma di governo in considerazione del sistema politico bipolare evidenziando che nella esperienza più recente si è fortemente incrementata la conflittualità tra i vari attori politici
Stereoselective synthesis of naturally-occurring 7-(hetero)aryl(2E,4E,6E)-2,4,6-heptatrienamides and their structural analogs
No full textA new and efficient highly stereoselective method to prepare naturally-occurring 7-(hetero)aryl (2E,4E,6E)-2,4,6-heptatrienamides and their structural analogues has been developed. The physical and spectral properties of one of these compounds, i.e. (2E,4E,6E)-7-(2-thienyl)-2,4,6-heptatrienoic acid piperidide (4 b), have been found to be quite different from those previously reported for 7-(2-thienyl)-2,4,6-heptatrienoic acid piperidide isolated from Othantus maritimus to which the (2E,4E,6E)-configuration had been previously assigned
Atene: la città cristiana
No full textA review of the monumental development of the Athenian Christian community in the early centuries
clearly shows the absence of a strong role of the episcopate, perhaps for reasons related to the ecclesiastical
organization of the diocese and to its economic resources. There is no evidence for any local Christian
personality contrasting the long and representative pagan tradition. The article also takes into account the
problem of the development of the Christian cemeteries in relation to the extension of the city considering
the problem of the two late antique circuit walls. A useful contribution to the knowledge of Athens in late
Antiquity comes also from the classical and late antique funerary inscriptions discovered in the Agora,
transported there from the external necropolis. The contexts of provenance of these documents contributes to
date their reuse and reveals a new phase of the Athenian public square
Development of a novel PVC-membrane fluorescent sensor based on N,N'-bis(dansylamidoethyl)-N,N'-bis(2-pyridylmethyl)propylenediamine as a new fluoroionophore for highly sensitive and selective monitoring of trace amounts of La3+ ions in aqueous solutions
No full textA new fluorescent sensor for the highly sensitive and selective determination of La3+ion isdeveloped. The sensing membrane was prepared by incorporating N,N-bis(dansylamidoethyl)-N,N-bis(2-pyridylmethyl)propylenediamine (L) as fluoroionophore in the plasticized PVC membranecontaining o-NPOE as plasticizer. The proposed sensor displays a wide calibration range of 5.0 × 10−9to 5.0 × 10−4M with a low limit of detection of 2.0 × 10−9M in a solution of pH 6.0. This sensor hasa relatively fast response time of less than 2 min. In addition to high stability and reproducibility, itshows a unique selectivity toward La3+ion with respect to common coexisting cations. The sensor canbe regenerated by exposure to a solution of EDTA. The proposed sensor was successfully applied to thedetermination of La3+ in aqueous solutions
Squaramide-based receptors in anion supramolecular chemistry: insights into anion binding, sensing, transport and extraction
Full text linkOver the last 15 years, squaramide-based receptors have attracted the attention of supramolecular chemists working in the field of anion recognition. Herein, we highlight examples of squaramide-based receptors that are able to bind, sense, extract and transport anions.Squaramides are a class of extremely versatile receptors for anion recognition, sensing, transport and extraction
New ionic [{2-(Me2NCH2)C6H4}(R)Sn{(EPPh2)2N}][(EPPh2)2N] (R = 2-(Me2NCH2)C6H4, nBu; E = O, S, Se) compounds. Solution behaviour and solid state structure
No full textThe new compounds [{2-(Me2NCH2)C6H4}(R)Sn{(EPPh2)2N}][(EPPh2)2N] [R = 2-(Me2NCH2)C6H4, E = O (1), S (2), Se (3) and R = nBu, E = O (4), S (5), Se (6)] were prepared by salt metathesis reactions between [2-(Me2NCH2)C6H4](R)SnCl2 and the potassium salt of the corresponding tetraorganodichalcogenoimidodiphosphinic acid in a 1:2 molar ratio. The multinuclear NMR studies (1H, 13C, 31P, 119Sn, and 77Se where appropriate) showed the equivalence of the 2-(Me2NCH2)C6H4 groups in 1 - 3 and non-equivalent organophosphorus ligands in 1 - 6. The compounds behave as 1:1 electrolytes in solution, with [{2-(Me2NCH2)C6H4}(R)Sn{(EPPh2)2N}]+ cations and [(EPPh2)2N]− anions. The single-crystal X-ray diffraction studies revealed an ionic structure for 2 and 3. An octahedral coordination environment is realized about tin by two C,N-coordinated 2-(Me2NCH2)C6H4 groups and a κ2-E,E'-chelating organophosphorus [(EPPh2)2N]ˉ anionic ligand. We found a dimeric structure with bridging OHˉ groups and monodentate S-organophosphorus ligands for the hydrolysis product [{2-(Me2NCH2)C6H4}(nBu)Sn(OH){(SPPh2)2N}]2 (5h)
A novel and efficient method to prepare 3-(hetero)aryl-1-propynes and its application to the stereoselective synthesis of (2E,4E)-N-(2-methylpropyl)-6-(2-methylpropyl)-6-(2-thienyl)-2,4-hexadienamide, piperovatine and (E)-N-(2-methylpropyl)-6-(4-methoxyphenyl)-4-hexyn-2-enamide
No full textChemically pure 3-(hetero)aryl-1-propynes, 13, have been prepared in high overall yields by a novel method which involves: (a) a copper(I)-mediated cross-coupling between a halomethyl(hetero)arene, 16, and trimethylsilethynylmagnesium bromide, 17, to give a trimethylsilyl-3-(hetero)aryl-1-propyne, 18; (b) removal of the trimethylsilyl group from 18 by treatment with potassium fluoride dihydrate in DMF. One of these 1-alkynes, i.e. 3-(2-thienyl)-1-propyne, 13a, has been employed in the key step of a highly stereoselective synthesis of naturally-occurring (2E,4E)-N-(2-methylpropyl)-6-(2-thienyl)-2,4-hexadienamide, 6. On the other hand, 3-(4-methoxyphenyl)-1-propyne, 13b, has been used either in two stereoselective syntheses of another natural N-(2-methylpropyl) amide, i.e. piperovatine, 7, or in the preparation of a structural analogue of 7, i.e. (E)-N-(2-methylpropyl)-6-(4-methoxyphenyl)-4-hexyn-2-enamide, 15
Selective and efficient syntheses of phototoxic 2,2':5',2''-terthiophene derivatives bearing a functional substituent in the 3'- or the 5-position
No full textEfficient and selective procedures have been developed to prepare on a medium scale several phototoxic 2,2':5',2"-terthiophene derivatives of general formula 2 and 3, which are characterized by a functional substituent in the 3'- or the 5-position. Most of these procedures, which are based on the construction of the 2,2':5',2"-terthiophene moiety and involve palladium-mediated carbon-carbon bond forming reactions, allow to overcome synthetic difficulties that may be found in the synthesis of compounds 2 and 3 starting from 2,2':5',2"-terthiophene (1a)
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