Annulation du retrait de DACA aux États-Unis : une décision aux effets contrastés

La Cour suprême des États-Unis a bloqué la décision de retrait par l’administration Trump d’un programme appelé DACA, qui protège de l’éloignement environ 800 000 étrangers en situation irrégulière arrivés aux États-Unis pendant leur enfance. Cette décision, fondée sur la méconnaissance par l’administration de la procédure administrative, protège temporairement les bénéficiaires de DACA. La Cour écarte toutefois les questions liées à la séparation des pouvoirs en matière d’immigration, et à la protection constitutionnelle des étrangers en situation irrégulière.The Supreme Court of the United States blocked the Trump’s administration decision to rescind a program called DACA, which protects about 800,000 unauthorized aliens who arrived in the United States as children from deportation. This decision, based on a violation of the Administrative Procedure Act, protects temporarily DACA recipients. However, the Court rules out questions relating to the separation of powers in immigration matters and the constitutional protection of irregular aliens

[2,2′-(2,6,9,13-Tetra­azatetra­decane-1,14-di­yl)diphenolato]iron(III) iodide

The title FeIII complex, [Fe(C22H32N4O2)]I, contains a six-coordinate FeN4O2 cation in which the ligand is a reduced Schiff base resulting from the NaBH4 reduction of the condensation product between salicylaldehyde and 1,5,8,12-tetra­azadodecane. In spite of the increased flexibility of the saturated backbone of the ligand compared to the Schiff base from which it was synthesized, the complex adopts a cis-FeN4O2 conformation for the phenolic O-atom donors, which contrasts with the trans conformation adopted by the analogous ClO4 − salt [Yisgedu et al. (2009 ▶). J. Chem. Crystallogr. 39, 315–319]. In addition to extensive N—H⋯I hydrogen bonding between the amine H atoms and the anion there is a weak C—H⋯I inter­action

An Organic Spin Crossover Material in Water from a Covalently Linked Radical Dyad

A covalently linked viologen radical cation dyad acts as a reversible thermomagnetic switch in water. Cycling between diamagnetic and paramagnetic forms by heating and cooling is accompanied by changes in optical and magnetic properties with high radical fidelity. Thermomagnetic switches in water may eventually find use as novel biological thermometers and in temperature-responsive organic materials where the changes in properties originate from a change in electronic spin configuration rather than a change in structure

L’essence pierreuse de l’homme : entre creusement et transfiguration de nos vestiges immémoriaux (Jules Supervielle, Paul Claudel)

International audienceThis paper proposes to create a dialogue between the poetic work of Jules Supervielle and that of Claudel’s « Five great Odes » using a motif that structures their works and which has not been studied until now: stone. Supervielle enjoyed Claudel’s lyricism so much that the same relationship to the immemorial emerges in his works: pushing regression in human time and searching the earth in a thousand places for human foundations. Both unearthed our immemorial vestiges: these witnesses made of stone. This study will question how the metamorphoses of these mythical foundations of man inspired these poets, how they dug and transmuted our stony foundations. The return to our immemorial origins founded on the one hand an eminently ontological dimension and on the other hand an imaginary dimension drawing the contours of a man who came out « alive from geology ».Cet article se propose de faire dialoguer l’œuvre poétique de Jules Supervielle avec celle du Claudel des Cinq grandes odes à l’aune d’un motif structurant leurs œuvres et pourtant nullement étudié jusqu’alors : la pierre. De fait, le Claudel lyrique que Supervielle aimait tant, nous amène à postuler l’idée selon laquelle un même rapport à l’immémorial se dessine dans ces œuvres : poussant la régression dans le temps humain et fouillant en mille lieux la terre à la recherche des fondations humaines, tous deux découvrent nos vestiges immémoriaux qui ne sont nuls autres que ces « témoins pierreux ». Cette étude interrogera les métamorphoses que ces fondations mythiques de l’homme inspirent à ces poètes : entre creusement et transfiguration de nos assises pierreuses, ce retour vers nos immémoriales origines fonde, d’une part, une parole poétique à la dimension éminemment ontologique et, d’autre part, un imaginaire dessinant les contours d’un homme sorti « vivant de la géologie »

Synthese et etude des proprietes magnetiques et structurales de complexes du fer (II) avec des ligands a noyaux imidazole et du manganese (II) avec des bases de schiff tridentees

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Concerted spin crossover and symmetry breaking yield three thermally and one light-induced crystallographic phases of a molecular material.

International audienc

A symmetry-breaking spin-state transition in iron(III)

Stepping up: A two-step magnetic spin transition with accompanying structural phase transitions is reported for the first time for FeIII. The transitions are observed at 187 K and 90 K on cooling with a hysteretic transition recorded upon heating during the first crossover at 106 K. The intermediate phase persists over 97 K and contains an unprecedented [HS-HS-LS] motif with tripling of the unit cell

Competing Symmetry Breaking and Spin Crossover in [FeH2L2?Me ](ClO4)2.

International audienceIn this contribution, we describe the symmetry breaking that appears in the low-spin phase of the spin crossover (SC) complex [FeH2L2-Me](ClO4)2, [H2L2-Me = Bis{[(2-methylimidazol-4-yl)methylidene]-3-aminopropyl}ethylenediamine], for which low-spin (LS) to high-spin (HS) transition may be thermally activated or photoinduced. In the LS phase stable at low temperature, a symmetry breaking occurs at around 120 K, while in the photoinduced HS (PIHS) state the high symmetry is recovered. The relaxation from this PIHS state to the LS low-symmetry phase occurs through an intermediate LS high-symmetry phase. The sequence of phases was evidenced by using magnetic susceptibility, X-ray diffraction, and infrared spectroscopy data