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[EN] A multistable spin crossover (SCO) molecular alloy system [Fe1-xMx(nBu-im)(3)(tren)](P1-yAsyF6)(2) (M = Zn-II, Ni-II; (nBu-im)(3)(tren) = tris(n-butyl-imidazol(2-ethylamino))amine) has been synthesized and characterized. By controlling the composition of this isomorphous series, two cooperative thermally induced SCO events featuring distinct critical temperatures (T-c) and hysteresis widths (Delta T-c, memory) can be selected at will. The pristine derivative 100As (x = 0, y = 1) displays a strong cooperative two-step SCO and two reversible structural phase transitions (PTs). The low temperature PTLT and the SCO occur synchronously involving conformational changes of the ligand's n-butyl arms and two different arrangements of the AsF6- anions [T-c(1) = 174 K (Delta T-c(1) = 17 K), T-c(2) = 191 K (Delta T-c(2) = 23 K) (scan rate 2 K min(-1))]. The high-temperature PTHT takes place in the high-spin state domain and essentially involves rearrangement of the AsF6- anions [T-c(PT) = 275 K (Delta T-c(PT) = 16 K)]. This behavior strongly contrasts with that of the homologous 100P [x = 0, y = 0] derivative where two separate cooperative one-step SCO can be selected by controlling the kinetics of the coupled PTLT at ambient pressure: (i) one at low temperatures, T-c = 122 K (Delta T-c = 9 K), for temperature scan rates (>1 K min(-1)) (memory channel A) where the structural modifications associated with PTLS are inhibited; (ii) the other centered at T-c = 155 K (Delta T-c = 41 K) for slower temperature scan rates <= 0.1 K min(-1) (memory channel B). These two SCO regimes of the 100P derivative transform reversibly into the two-step SCO of 100As upon application of hydrostatic pressure (ca. 0.1 GPa) denoting the subtle effect of internal chemical pressure on the SCO behavior. Precise control of AsF6- <-> PF6- substitution, and hence of the PTLT kinetics, selectively selects the memory channel B of 100P when x = 0 and y approximate to 0.7. Meanwhile, substitution of Fe-II w

[EN] The synthesis, structural characterization and magnetic properties of two new isostructural porous 3D compounds with the general formula {FeII(pina)[MI(CN)2]2}·xMeOH (x = 0¿5; pina = N-(pyridin-4-yl)isonicotinamide; MI = AgI and x ~ 5 (1·xMeOH); MI = AuI and x ~ 5 (2·xMeOH)) are presented. The single-crystal X-ray diffraction analyses have revealed that the structure of 1·xMeOH (or 2·xMeOH) presents two equivalent doubly interpenetrated 3D frameworks stabilized by both argentophilic (or aurophilic) interactions and interligand C¿O···HC H-bonds. Despite the interpenetration of the networks, these compounds display accessible void volume capable of hosting up to five molecules of methanol which interact with the host pina ligand and establish an infinite lattice of hydrogen bonds along the structural channels. Interestingly, the magnetic studies have shown that solvated complexes 1·xMeOH and 2·xMeOH display two- and four-step hysteretic thermally driven spin transitions, respectively. However, when these compounds lose the methanol molecules, the magnetic behavior changes drastically giving place to gradual spin conversions evidencing the relevant influence of the guest molecules on the spin-crossover properties. Importantly, since the solvent desorption takes place following a single-crystal-to-single-crystal transformation, empty structures 1 and 2 (x = 0) could be also determined allowing us to evaluate the correlation between the structural changes and the modification of the magnetic properties triggered by the loss of methanol molecules.

[EN] We report an unprecedented series of two-dimensional (2D) spin-crossover (SCO) heterobimetallic coordination polymers generically formulated as {Fe-II[(He(SCN)(3))(2)](L)(x))}center dot Solv, where x = 2 for L = tvp (trans-(4,4'-vinylenedipyridine)) (1tvp), bpmh ((1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine) (1bpmh center dot nCH(3)OH; n = 0, 1), by eh ( (1E,2E)-1,2-bis (1-(pyridin-4-yl) ethyliden e) hydrazine) (Ibpeh center dot nH(2)O; n = 0, 1) and x = 2.33 for L = 0 0 bpbz (1,4-bis(pyridin-4-yl)benzene) (1bpbz center dot nH(2)O; n = 0, 2/ 3). The results confirm that self-assembly of Fell, [Hg-II(SCN)(4)](2-), and ditopic rodlike bridging ligands L containing 4-pyridyl moieties favors the formation of linear [Fe(mu-L)](n)(2n+) chains and in situ generated binuclear units {[Hg-II(SCN)(3)](2)(mu-L)}(2)-. The latter act as bridges between adjacent chains generating robust 2D layers. The [(FeN6)-N-II] centers are equatorially surrounded by four NCS- groups and two axial N atoms of the organic ligand L. The compound 1tvp and the unsolvated form of 1bpmh undergo complete SCO centered at T-1/2 = 177 and 226 K, characterized by the enthalpy and entropy variations Delta H = 12.3 and 10.5 kJ mol(-1) and Delta S = 69.4 and 48 J KT-1 mol(-1), respectively. The almost complete SCO of the unsolvated form of 1bpeh occurs at ca. T-1/2 = 119 K and exhibits a complete LIESST effect. Regardless of the degree of solvation, a half-spin conversion at T-1/2 < 100 K occurs for 1bpbz center dot nH(2)O, which becomes almost complete at p = 0.65 GPa. The labile solvent molecules present in 1bpmh center dot CH3OH and 1bpely center dot H2O have a dramatic influence on the corresponding SCO behavior.

[EN] Two new 3D spin-crossover (SCO) Hofmann-type coordination polymers {Fe(2,6-naphthy)[Ag(CN)2][Ag2(CN)3]} (1; 2,6-naphthy = 2,6-naphthyridine) and {Fe(2,6-naphthy)- [Au(CN)2]2}·0.5PhNO2 (2) were synthesized and characterized. Both derivatives are made up of infinite stacks of {Fe[Ag(CN)2]2- [Ag2(CN)3]}n and {Fe[Au(CN)2]2}n layered grids connected by pillars of 2,6-naphthy ligands coordinated to the axial positions of the FeII centers of alternate layers.

[EN] Fe-II spin-crossover (SCO) coordination polymers of the Hofmann type have become an archetypal class of responsive materials. Almost invariably, the construction of their architectures has been based on the use of monotopic and linear ditopic pyridine like ligands. In the search for new Hofmann-type architectures with SCO properties, here we analyze the possibilities of bridging ligands with higher connectivity degree. More precisely, the synthesis and structure of {Fe-II(L-N3)[M-I(CN)(2)](2)}center dot(Guest) (Guest = nitro-benzene, benzonitrile, o-dichlorobenzene; M-I = Ag, Au) and {Fe-II(L-N4)[Ag-2(CN)(3)][Ag(CN)(2)]}center dot H2O are described, where L-N3 and L-N4 are the tritopic and tetratopic ligands 1,3,5-tris(pyridin-4-ylethynyl)benzene and 1,2,4,5-tetrakis(pyridin-4-ylethynyl)benzene. This new series of Hofmann clathrates displays thermo- and photoinduced SCO behaviors.

En la actual formación universitaria,se reflexiona sobre los métodos usados en laenseñanza, así como en el tiempo empleado porlos alumnos en asimilar los conocimientosligados a cada materia. Ambos aspectos, sereflejan en la elaboración de la guía particularde cada asignatura. Esta visión hace que elmétodo de enseñanza tradicional de lasmaterias, utilizando clases magistrales, sólo esuna parte en la cadena del aprendizaje. Con elánimo de contribuir a esa nueva perspectiva, seha creado el trabajo que a continuación sepresenta. Un instrumento virtual, desarrolladocon el software LabVIEW® (Laboratory VirtualEngineering workbench), que permite laconexión entre el ordenador y el puesto dellaboratorio. Con esta aplicación, se quierefavorecer el grado de implicación por parte delalumno en el proceso de enseñanza –aprendizaje y proporcionar herramientas conlas que los alumnos puedan construir suconocimiento.