Single ion magnet behaviour in a two-dimensional network of dicyanamide-bridged cobalt(II) ions

A novel two-dimensional coordination polymer of the formula [Co(dca)2(atz)2]n (1) resulted from assembling trans-bis(2-amino-1,3,5-triazine)cobalt(II) motifs by dicyanamide spacers. Variabletemperature dc and ac magnetic susceptibility measurements of 1 show that the high-spin cobalt(II) ions act as single ion magnets (SIMs)

[Cr(dmbipy)(ox)2]−: a new bis-oxalato building block for metal assembling. Crystal structures and magnetic properties of XPh4[Cr(dmbipy)(ox)2]·5H2O (X = P and As), {Ba(H2O)2[Cr(dmbipy)(ox)2]2}n·17/2nH2O and {Ag(H2O)[Cr(dmbipy)(ox)2]}n·3nH2O

The synthesis, X-ray structure and variable-temperature magnetic study of new compounds of formula PPh4 [Cr(dmbipy)(ox)2 ]$5H2O (1), AsPh4 [Cr(dmbipy)(ox)2 ]$5H2O (2), {Ba(H2O)2[Cr(dmbipy)(ox)2]2}n$17/2nH2O (3) and {Ag(H2O)[Cr(dmbipy)(ox)2]}n$3nH2O (4) (PPh4 + ¼ tetraphenylphosphonium cation; AsPh4 + ¼ tetraphenylarsonium cation; dmbipy ¼ 4,4 0 -dimethyl- 2,2 0 -bipyridine; ox 2 ¼ oxalate dianion) are reported herein. The isomorphous compounds 1 and 2 are made up of discrete [Cr(dmbipy)(ox)2] anions, XPh4 + cations [X ¼ P (1) and As (2)] and uncoordinated water molecules. The chromium environment in 1 and 2 is distorted octahedral with Cr–O and Cr–N bond distances varying in the ranges 1.950(2)–1.9782(12) and 2.047(3)–2.0567(14) A˚ , respectively. The angles subtended at the chromium atom by the two bidentate oxalate ligands cover the range 82.58(10)– 83.11(5) , and they are somewhat greater than those concerning the chelating dmbipy [79.04(10) (1) and 79.24(5) (2)]. The [Cr(dmbipy)(ox)2] unit of 1 and 2 also occurs in 3 and 4 but it adopts different coordination modes. It acts as a chelating ligand through its two oxalate groups towards the divalent barium cations in 3 affording neutral chains with diamond-shaped units sharing the barium atoms, while the two other corners are occupied by two crystallographically independent chromium atoms. The barium atom in 3 is coordinated by eight oxygen atoms from four oxalate groups and two aqua ligands. The structure of 4 consists of neutral bimetallic layers where the [Cr(dmbipy)(ox)2] unit acts as a ligand towards the univalent silver(I) cation through its two oxalate groups, one of them being bidentate and the other bidentate/monodentate (outer). Each silver atom is six-coordinated with a water molecule and five oxygen atoms from three oxalate groups building a highly distorted octahedral environment. Magnetic susceptibility measurements for 1–4 in the temperature range 1.9– 300 K show the occurrence of weak ferro- (1 and 2) and antiferromagnetic (3 and 4) interactions which are mediated by p–p stacking between dmbipy ligands through the spin polarization mechanism. A comparative study of the potentiality of the [Cr(AA)(ox)2] unit (AA ¼ bidentate nitrogen donor) as a building bl

Confirmen la idoneïtat de la citologia per al cribratge de càncer anal en població d'alt risc

Investigadors de l'Hospital del Mar i de la UAB han realitzat un estudi que constata l'eficàcia d'usar la tècnica de la citologia per detectar i diagnosticar lesions cancerígenes anals en persones d'alt risc. L'elevada prevalença del Virus del Papil·loma Humà confirma també la pertinència d'usar el test d'aquest grup de virus. A més, la convivència amb altres infeccions fa necessari establir un protocol d'actuació multidisciplinari per abordar aquest tipus de lesions.investigadores del Hospital del Mar y de la UAB han realizado un estudio que constata la eficacia de usar la técnica de la citología para detectar y diagnosticar lesiones cancerígenas anales en personas de alto riesgo. La elevada prevalencia del Virus del Papiloma Humano apoya también la pertinencia de usar el test de este grupo de virus. Además, la convivencia con otras infecciones requiere establecer un protocolo de actuación multidisciplinar para abordar este tipo de lesiones

A novel supramolecular assembly in an iron(III) compound exhibiting magnetic ordering at 70 K

Ethyl-substituted ammonium cation allows the preparation of an unprecedented oxo- and oxalato-bridged supramolecular three-dimensional network. The compound exhibits magnetic ordering with Tc = 70 K due to a weak spin canting.Julve Olcina, Miguel, [email protected] ; Lloret Pastor, Francisco, [email protected]

Self-assembly, binding ability and magnetic properties of dicopper(ii) pyrazolenophanes

A novel series of dinuclear copper(II) pyrazolenophanes of the formula [Cu-2(mu-4-Mepz)(2)(mu-ClO4)(ClO4)(bpm)(2)] (1), [Cu-2(mu-pz)(2)(mu-H2O)(ClO4)(4,7-Me(2)phen)(2)]ClO4 center dot H2O center dot CH3CN (2), [Cu-2(mu-pz)(2)(mu-H2O)(ClO4)(3/2)(H2O)(1/2)(phen)(2)](2)[Cu-2(mu-pz)(2)(mu-ClO4)(ClO4)(2)(phen)(2)]center dot 8H(2)O (3), and [Cu-2(mu-pz)(2)(CH3CN)(2)(3,4,7,8-Me(4)phen)(2)](ClO4)(2) (4) (Hpz = pyrazole, H-4-Mepz = 4-methylpyrazole, bpm = 2,2'-bipyrimidine, phen = 1,10-phenanthroline, 4,7-Me(2)phen = 4,7-dimethyl-1,10-phenanthroline, and 3,4,7,8-Me(4)phen = 3,4,7,8-tetramethyl-1,10-phenanthroline) have been synthesized and magneto-structurally investigated. The crystal structures of 1-4 contain bis(pyrazolate)(perchlorate)-(1 and 3), bis(pyrazolate)(aqua)-(2 and 3), or bis(pyrazolate)-bridged (4) dicopper(II) entities of the metallacyclophane-type with bpm (1), 4,7-Me(2)phen (2), phen (3), and 3,4,7,8-Me(4)phen (4) as blocking bidentate ligands. All of them exhibit a saddle conformation with an overall not planar but bent, six-membered Cu-(N-N')(2)-Cu metallacyclic core with relatively short intermetallic distances across the bis(pyrazolate)(perchlorate) [r = 3.3076(5) (1) and 3.382(1) angstrom (3)], bis(pyrazolate)(aqua) [r = 3.383(1) (2) and 3.357(1) angstrom (3)], and bis(pyrazolate) bridges [r = 3.098(1) angstrom (4)]. The analyses of the variable-temperature magnetic susceptibility of 1-4 reveal the occurrence of a moderately strong antiferromagnetic coupling across the bis(pyrazolate)(perchlorate) [-J = 228 (1) and 193 cm(-1) (3)], bis(pyrazolate)(aqua) [-J = 189 (2) and 221 cm(-1) (3)], and bis(pyrazolate) bridges [-J = 197 cm(-1) (4)] (the spin Hamiltonian being defined as H = -JS(1).S-2 with S-1 = S-2 = S-Cu = 1/2).A novel series of dinuclear copper(II) pyrazolenophanes of the formula [Cu2(μ-4-Mepz)2(μ-ClO4)(ClO4)(bpm)2] (1), [Cu2(μ-pz)2(μ-H2O)(ClO4)(4,7-Me2phen)2]ClO4·H2O·CH3CN (2), [Cu2(μ-pz)2(μ-H2O)(ClO4)3/2(H2O)1/2(phen)2]2[Cu2(μ-pz)2(μ-ClO4)(ClO4)2(phen)2]·8H2O183437449COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESsem informaçãoThis work was supported by the Ministerio Español de Economía y Competitividad (Project CTQ2013-44844P and Unidad de Excelencia MDM-2015-0538) and the Generalitat Valenciana (PROMETEOII/2014/070). We also acknowledge the financial support from Brazilian

Design of Magnetic Coordination Polymers Built from Polyoxalamide Ligands: A Thirty Year Story

International audienceThe aim of this review is to pay tribute to the legacy of O. Kahn. Kahn's credo was to synthesize magnetic compounds with predictable structure and magnetic properties. This is illustrated herein with results obtained by Kahn's group during his Orsay period thirty years ago, but also on the basis of our recent results on the synthesis of coordination polymers with oxamate ligands. The first part of this review is devoted to a short description of the necessary knowledge in physics and theoretical chemistry that Kahn and his group have used to select oxamate ligands, the complex‐as‐ligand strategy and the synthesis of heterobimetallic systems. Then, we describe the strategies we have later used to obtain the desired target compounds. The use of complexes as building‐blocks, associated to a control of the metal ions chirality and stoichiometry, allowed us to obtain coordination polymers with predictable dimensionality. For the synthesis of single‐chain magnets (SCMs) we show that the ligand chemical flexibility makes the isolation of the chains in the solid and the occurence of slow magnetic relaxation possible. For 1D and 2D molecule‐based magnets (MBMs), the magnetic ordering strongly depends on the interchain or interplane interactions, which are difficult to control. Again the flexibility of the oxamate ligands allowed their strengthening in the solid sate, yielding MBMs with critical temperatures up to 30 K. We will also present our results on 3D coordination polymers, particularly on the porous magnets displaying large octagonal channels. This family of porous MBMs possess outstanding chemical properties, such as post‐synthetic transformation in the solid state. Finally, we will also show that oxamate ligands allows the design of multifunctional materials, as in the case of the first chiral SCM. Overall, the results presented in this review show the impressive potential the oxamate ligands have for the design of coordination polymers