Poly[[hexa­aqua­tris­[μ2-2,5-dihy­droxy-1,4-benzoquinona­to(2−)]diholmium(III)] octa­deca­hydrate]

In the polymeric title compound, {[Ho2(C6H2O4)3(H2O)6]·18H2O}n, the HoIII ion is nine-coordinated by six O atoms derived from three bidentate 2,5-dihy­droxy-1,4-benzoquinonate (DHBQ2−) ligands and three O atoms from three water mol­ecules. The HoIII ions are connected via three ligands, resulting in the formation of a two-dimensional honeycomb layer parallel to the ab plane. The layer is racemic in which Δ- and Λ-coordination geometries around HoIII ions are alternately arranged. The asymmetric unit comprises a third of a HoIII ion, located on a threefold axis, one-half of a DHBQ2− ion, located on a centre of inversion, one coordinated water mol­ecule and three uncoordinated water mol­ecules

Poly[[diaqua­deca-μ-cyanido-hexa­cyanidobis­(4-cyano­pyridine)di-μ-pyrimidine-tricopper(II)ditungsten(V)] dihydrate]

In the polymeric title compound, {[Cu3W2(CN)16(C4H4N2)2(C6H4N2)2(H2O)2]·2H2O}n, the coordination geometry of W is an eight-coordinated bicapped trigonal prism. Five of the CN groups of [W(CN)8] are bridged to Cu ions. The coordination geometries of the Cu atoms are each pseudo-octa­hedral; one Cu atom is located on a centre of inversion. The cyano-bridged W–Cu layers are linked by Cu-containing pillars, to form a three-dimensional network with cavities occupied by noncoordinated water and 4-cyano­pyridine mol­ecules

Tetra­potassium hepta­cyanido­molybdate(III) dihydrate

The asymmetric unit of the title compound, KI 4[MoIII(CN)7]·2H2O, consists of one [Mo(CN)7]4− anion, four K+ cations, and two water mol­ecules. The [MoIII(CN)7]4− anion has a seven-coordinated capped-trigonal-prismatic coordination geometry. The site-occupancy factors of the disordered water mol­ecules were set at 0.90, 0.60 and 0.50. The H-atom positions could not be determined for two of the water mol­ecules. The H atoms of the water with a site-occupancy factor of 0.90 were refined using O—H and H⋯H distance restraints

Poly[[hexa-μ-cyanido-manganese(II)iron(III)] penta­hydrate]

The structure of the title compound, MnII[FeIII(CN)6]2/3·5H2O, features a face-centered cubic –Mn—NC—Fe– framework with both Mn and Fe having site symmetry m m. Since one-third of the [Fe(CN)6]3− units are missing for a given formula in order to maintain charge neutrality, each Mn atom around such a vacancy is coordinated not only by the N atoms of the CN groups but also by the O atoms of the ligand water mol­ecules. In addition to ligand water mol­ecules, two types of non-coordinated water mol­ecules, so-called zeolitic water mol­ecules, exist in the inter­stitial sites of the –Mn—NC—Fe– framework. The positions of the O atoms of the zeolitic water mol­ecules are fixed by the linkage via hydrogen bonds between ligand water and zeolitic water mol­ecules. The structure is related to a recently reported rubidium manganese hexa­cyano­ferrate. Site occupancy factors for Fe, C, N are 0.67; for two O atoms the value is 0.83 and for one O atom is 0.17

Modifications of EHPDB physical properties through doping with Fe2O3Fe_2O_3 nanoparticles (part II)

The aim of our study was to analyze the influence of various concentrations of γ-Fe(2)O(3) nanoparticles on the physical properties of the liquid crystalline ferroelectric SmC* phase, as well as to check the effect of introducing nanoparticles in the LC matrix on their properties in the prepared five nanocomposites. UV-vis spectroscopy showed that the admixture reduced the absorption of nanocomposites in the UV range, additional absorption bands appeared, and all nanocomposites were transparent in the range of 500–850 nm. The molecular dynamics in particular phases of the nanocomposites were investigated by the dielectric spectroscopy method, and it was found that nanoparticles caused a significant increase in the dielectric constant at low frequencies, a strong modification of the dielectric processes in the SmC* phase, and the emergence of new relaxation processes for the highest dopant concentrations. SQUID magnetometry allowed us to determine the magnetic nature of the nanoparticles used, and to show that the blocked state of nanoparticles was preserved in nanocomposites (hysteresis loops were also registered in the ferroelectric SmC* phase). The dependence of the coercive field on the admixture concentration and the widening of the hysteresis loop in nanocomposites in relation to pure nanoparticles were also found. In turn, the FT-MIR spectroscopy method was used to check the influence of the impurity concentration on the formation/disappearance or modification of the absorption bands, and the modification of both the FWHM and the maximum positions for the four selected vibrations in the MIR range, as well as the discontinuous behavior of these parameters at the phase transitions, were found