Barbara Sieklucka

Jagiellonian University, Cracovia, Lesser Poland Voivodeship, Poland

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Publications (140)469.24 Total impact

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    ABSTRACT: The unique enantiopure {[Λ-Co(II)((R)-mpm)2]3[W(V)(CN)8]2}·9H2O [(R)-1] and {[Δ-Co(II)((S)-mpm)2]3[W(V)(CN)8]2}·9H2O [(S)-1], where mpm = α-methylpyridinemethanol, magnetic spongelike materials, crystallizing in the chiral P21 space group, are constructed of cyanido-bridged {Co3W2} trigonal bipyramids with three cis-[Co(II)(mpm)2(μ-NC)2] moieties in equatorial sites and two [W(V)(CN)8](3-) units in apical positions. The arrangement of {Co3W2} clusters in the crystal lattice is controlled by interactions with crystallization H2O molecules, resulting in two independent hydrogen-bonding systems: the first weaving along open channels in the a direction (weakly bonded H2O) and the second closed in the cages formed by the surrounding [W(CN)8](3-) and mpm fragments (strongly bonded H2O). The strong optical activity of (R)- and (S)-1 together with continuous chirality measure (CCM) analysis confirms the chirality transfer from enantiopure (R)- and (S)-mpm to [Co(mpm)2(μ-NC)2] units, a cyanido-bridged skeleton, and to the whole crystal lattice. Magnetic properties confronted with ab initio calculations prove the ferromagnetic couplings within Co(II)-NC-W(V) linkages inside {Co3W2} molecules, accompanied by weak antiferromagnetic intermolecular interactions. The reversible removal of weakly bonded H2O above 50 °C induces the structural phase transition 1 ⇄ 1deh and strongly affects the magnetic characteristics. The observed changes can be interpreted in terms of the combined effects of the decreasing strength of ferromagnetic Co(II)-W(V) coupling and the increasing role of antiferromagnetic intermolecular correlation, both connected with dehydration-induced structural modifications in the clusters' core and supramolecular network of 1.
    Inorganic Chemistry 05/2015; DOI:10.1021/acs.inorgchem.5b00470 · 4.79 Impact Factor
  • CrystEngComm 05/2015; DOI:10.1039/C5CE00414D · 3.86 Impact Factor
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    ABSTRACT: Complexes of lanthanides(III) (Ce-Yb) with 2,2'-bis(2-oxazoline) (Box) combined with octacyanidomolybdate(V) gave a series of magneto-luminescent coordination polymers, {[Ln(III)(Box)n(DMF)m][Mo(V)(CN)8]}·x(solvent) (1-12). They are built of cyanido-bridged layers of a mixed 4- and 8-metal rings topology and show unique sliding of layers dependent on a 4f metal ion. For light lanthanides, dominant phase A, {[Ln(III)(Box)2(DMF)2][Mo(V)(CN)8]}·1.5MeCN (Ln = Ce, 1; Pr, 2; Nd, 3), consists of ideally aligned, not shifted layers, giving large channels (13.7 × 14.0 Å). Intermediate lanthanides reveal phase B, {[Ln(III)(Box)2(DMF)2] [Mo(V)(CN)8]}·H2O (Ln = Sm, 4; Eu, 5; Gd, 6; Tb, 7; Dy, 8), of smaller pores (8.4 × 10.6 Å) due to layer-H2O hydrogen bonding, which induces sliding of CN(-)-bridged layers. Heavy lanthanides show phase C, {[Ln(III)(Box)(DMF)3][Mo(V)(CN)8]}·MeCN (Ln = Ho, 9; Er, 10; Tm, 11; Yb, 12), with large channels (13.7 × 13.7 Å) of a similar size to light lanthanides. This effect comes from the changes in Ln(III) coordination sphere affecting solvent-layer interactions. Compounds 1-12 reveal diverse emission depending on the interaction between Ln(III) and Box luminophors. For 2-5, 9, and 12, the ligand-to-metal energy-transfer-induced visible f-centered emission ranging from green for Ho(III)-based 9, orange from Sm(III)-based 4, to red for Pr(III)- and Eu(III)-containing 2 and 5, respectively. Near-infrared emission was found for 2-4, 9, and 12. Red phosphorescence of Box was detected for Gd(III)-based 6, whereas the selective excitation of ligand or Ln(III) excited states resulting in the switchable red to green emission was found for Tb(III)-based 7. The materials revealed Ln(III)-Mo(V) magnetic coupling leading to ferromagnetism below 2.0 and 2.2 K for 4 and 7, respectively. The onset of magnetic ordering at low temperatures was found for 6 and 8. Compounds 1-12 form a unique family of cyanido-bridged materials of a bifunctional magneto-luminescence character combined with dynamic structural features.
    Inorganic Chemistry 05/2015; DOI:10.1021/acs.inorgchem.5b00040 · 4.79 Impact Factor
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    ABSTRACT: A new crystalline pseudo-polymorphic form of the 2-D microporous honeycomb-like magnetic network {[Ni(cyclam)]3[W(CN)8]2·solv}n was obtained in the reaction between methanol-soluble {Ni[Ni(MeOH)3]8[W(CN)8]6} clusters and the [Ni(cyclam)]2+ complex in acetonitrile-rich solvent mixture. In comparison to the three earlier characterised pseudo-polymorphs, which all crystallised in the triclinic space group P-1, the new form shows higher symmetry of C2/m, greater porosity of ca. 40% solvent accessible volume, and the highest magnetic ordering temperature of 12 K. It undergoes an irreversible single-crystal-to-single-crystal transformation to the hexadecahydrate form that is stable in air at ambient temperature. New synthetic pathway leading directly to methanol solvate of the same network, which was previously obtained by sorption of MeOH into the anhydrous form, is also reported.
    CrystEngComm 04/2015; 17(18). DOI:10.1039/C5CE00287G · 3.86 Impact Factor
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    ABSTRACT: The self-assembly of iron(II) ions with rare octacyanidorhenate(V) metalloligands in a methanolic solution results in the formation of a nanometric pentadecanuclear {FeII9[ReV(CN)8]6(MeOH)24}⋅10 MeOH (1) molecule with a six-capped body-centered cubic topology. The cluster demonstrates a thermally-induced spin-crossover phase transition at T1/2=195 K which occurs selectively for a single FeII ion embedded in the center of a cluster core.
    Angewandte Chemie 03/2015; 127(17). DOI:10.1002/ange.201500288
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    ABSTRACT: The self-assembly of iron(II) ions with rare octacyanidorhenate(V) metalloligands in a methanolic solution results in the formation of a nanometric pentadecanuclear {Fe(II) 9 [Re(V) (CN)8 ]6 (MeOH)24 }⋅10 MeOH (1) molecule with a six-capped body-centered cubic topology. The cluster demonstrates a thermally-induced spin-crossover phase transition at T1/2 =195 K which occurs selectively for a single Fe(II) ion embedded in the center of a cluster core. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition in English 03/2015; 54(17). DOI:10.1002/anie.201500288 · 13.45 Impact Factor
  • ChemInform 03/2015; 46(9). DOI:10.1002/chin.201509296
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    ABSTRACT: Octacyanidometallates make an important branch of cyanide-based molecular magnets that not only follow the trends in modern magnetochemistry and materials science but also have stimulated these fields from the very beginning and still blaze a trail by introducing new concepts such as heterotrimetallic systems, new functionalities and cross-effects like photo-switching of magneto-optical properties and setting new records in magnetic ordering temperatures or magnetic exchange interactions. The following paper focuses on a special class of molecular magnets which, to the best of our knowledge, have not been reviewed so far: octacyanide-based magnetic clusters. A complete list of all known molecules incorporating octacyanides with an extensive discussion of their structures, topologies and magnetic properties, with special attention paid to multifunctional systems, is provided. Several milestone-clusters are discussed thoroughly to emphasize their particular importance in the development of crystal engineering and molecular magnetism.
    01/2015; 2(1). DOI:10.1039/C4QI00189C
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    ABSTRACT: Pyrazine-N,N'-dioxide (pzdo) was used as a linker in the design and synthesis of hybrid octacyanometalate-based networks. Four new compounds Na-6[W-v(CN)(8)](2)(pzdo)(7)center dot 5H(2)O (1), K-3 [W-V(CN) (8)](p z d o)(2)center dot 4 H2O (2), {Mn-6(II)(pzdo)(4)(MeOH)(10)[W-V(CN)(8)](4)}center dot 4MeOH (3), and {Mn-2(II)(pzdo)(H2O)(4)[W-V(CN)(8)]}center dot 4H(2)O (4) reveal specific Mpzdo-[W(CN)(8)](3-/4-) (M = Na-I, Mn-II) structural arrangements where pzdo plays a significant role. Apart from typical supramolecular interactions including hydrogen bonding and van der Waals interactions, the {[M(mu-pzdo)M][W(CN)(8)](x)} (x = 1 or 2) structural motifs in 1-4 are organized by specific supramolecular interactions of the pzdo molecule and the octacyanotungstate anions: face-to-face sandwich type interactions between the plane of the pzdo aromatic ring and N-4 square face of [W(CN)(8)](n-) anions, edge-to-face interactions between the plane of the pyrazine ring and a pair of neighboring N-CN atoms of the [W(CN)(8)]-moiety, and end-to-face interactions between the plane of the pyrazine ring and a single N-CN atoms of the [W(CN)8]-moiety. The related intermolecular arrangements show features typical for anion-pi interactions, unprecedented in the octacyanometalate chemistry. The specific interactions of the octacyanotungstate and the pzdo molecule in 1 and 2 lead to significant modification of their electronic spectra. Magnetic studies revealed that 1, 2, and 4 are paramagnetic, although 3 orders antiferromagnetically at T-c = 17.5 K.
    Crystal Growth & Design 08/2014; 14(8). DOI:10.1021/cg500636m · 4.56 Impact Factor
  • Chemistry of Materials 07/2014; 26(14):4072-4075. DOI:10.1021/cm501954e · 8.54 Impact Factor
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    ABSTRACT: Two chiral luminescent derivatives of pyridine bis(oxazoline) (Pybox), (SS/RR)-iPr-Pybox (2,6-bis[4-isopropyl-2-oxazolin-2-yl]pyridine) and (SRSR/RSRS)-Ind-Pybox (2,6-bis[8H-indeno[1,2-d]oxazolin-2-yl]pyridine), have been combined with lanthanide ions (Gd(3+) , Nd(3+) ) and octacyanotungstate(V) metalloligand to afford a remarkable series of eight bimetallic CN(-) -bridged coordination chains: {[Ln(III) (SS/RR-iPr-Pybox)(dmf)4 ]3 [W(V) (CN)8 ]3 }n ⋅dmf⋅4 H2 O (Ln=Gd, 1-SS and 1-RR; Ln=Nd, 2-SS and 2-RR) and {[Ln(III) (SRSR/RSRS-Ind-Pybox)(dmf)4 ][W(V) (CN)8 ]}n ⋅5 MeCN⋅4 MeOH (Ln=Gd, 3-SRSR and 3-RSRS; Ln=Nd, 4-SRSR and 4-RSRS). These materials display enantiopure structural helicity, which results in strong optical activity in the range 200-450 nm, as confirmed by natural circular dichroism (NCD) spectra and the corresponding UV/Vis absorption spectra. Under irradiation with UV light, the Gd(III) -W(V) chains show dominant ligand-based red phosphorescence, with λmax ≈660 nm for 1-(SS/RR) and 680 nm for 3-(SRSR/RSRS). The Nd(III) -W(V) chains, 2-(SS/RR) and 4-(SRSR/RSRS), exhibit near-infrared luminescence with sharp lines at 986, 1066, and 1340 nm derived from intra-f (4) F3/2 →(4) I9/2,11/2,13/2 transitions of the Nd(III) centers. This emission is realized through efficient ligand-to-metal energy transfer from the Pybox derivative to the lanthanide ion. Due to the presence of paramagnetic lanthanide(III) and [W(V) (CN)8 ](3-) moieties connected by cyanide bridges, 1-(SS/RR) and 3-(SRSR/RSRS) are ferrimagnetic spin chains originating from antiferromagnetic coupling between Gd(III) (SGd =7/2) and W(V) (SW =1/2) centers with J1-(SS) =-0.96(1) cm(-1) , J1-(RR) =-0.95(1) cm(-1) , J3-(SRSR) =-0.91(1) cm(-1) , and J3-(RSRS) =-0.94(1) cm(-1) . 2-(SS/RR) and 4-(SRSR/RSRS) display ferromagnetic coupling within their Nd(III) -NC-W(V) linkages.
    Chemistry - A European Journal 06/2014; 20(23). DOI:10.1002/chem.201304772 · 5.70 Impact Factor
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    ABSTRACT: Trinuclear chiral (LH)2L2Cu3 (LH = 1,3-diamino-2-propanol, bdapH) assemblies linked by octacyanidometalate(IV) form isostructural one-dimensional (1D) chains consisting of right- and left-handed helixes arranged in an alternate manner: [(bdapH)2(bdap)2Cu(II)3][M(IV)(CN)8]·H2O (M = Mo 1, W 2). Each chain displays helicity with a long pitch around 17.2 Å. The direction of the helix rotation is strictly connected with the conformation of the (LH)2L2Cu3 unit. Right-handed helixes are based on Δ-S,S-(LH)2L2Cu3, whereas left-handed ones contain Λ-R,R-(LH)2L2Cu3 units. Magnetic studies reveal antiferromagnetic interactions through alkoxo-bridges inside trinuclear Cu(II) nodes leading to an ST = 1/2 ground state for both assemblies.
    Inorganic Chemistry 03/2014; 53(7). DOI:10.1021/ic500271f · 4.79 Impact Factor
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    ABSTRACT: A bimetallic pentadecanuclear cyanido-bridged {Fe9[W(CN)8]6 (MeOH)24}·xMeOH cluster of an Fe(II/III)-W(IV/V) mixed valence nature, reveals a reversible single-crystal-to-single-crystal transformation, concomitant with metal-to-metal charge transfer between Fe and W ions. The dominance of (HS)Fe(II)-NC-W(V) units at a high temperature, and (HS)Fe(III)-NC-W(IV) units at a low temperature, leads to an unprecedented reversed thermal hysteresis loop in magnetic measurements.
    Chemical Communications 02/2014; DOI:10.1039/c3cc48029a · 6.72 Impact Factor
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    ABSTRACT: Magnetocaloric effect in {[Fe(pyrazole)4]2[Nb(Cn)8]·4H2O}n molecular magnet is reported. It crystallizes in tetragonal I41/a space group. The compound exhibits a phase transition to a long range magnetically ordered state at Tc≈8.3K. The magnetic entropy change ΔSM as well as the adiabatic temperature change ΔTad due to applied field change μ0ΔH=0.1, 0.2, 0.5, 1, 2, 5, 9 T as a function of temperature have been determined by the relaxation calorimetry measurements. The maximum value of ΔSM for μ0ΔH is 4.9 J mol−1 K−1 (4.8 J kg−1 K−1) at 10.3 K. The corresponding maximum value of ΔTad is 2.0 K at 8.9 K. The temperature dependence of the exponent n characterizing the field dependence of ΔSM has been estimated. It attains the value of 0.64 at the transition temperature, which is consistent with the 3D Heisenberg universality class.
    Journal of Magnetism and Magnetic Materials 12/2013; DOI:10.1016/j.jmmm.2013.11.047 · 2.00 Impact Factor
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    ABSTRACT: Different aspects of critical behaviour of magnetic materials are presented and discussed. The scaling ideas are shown to arise in the context of purely magnetic properties as well as in that of thermal properties as demonstrated by magnetocaloric effect or combined scaling of excess entropy and order parameter. Two non-standard approaches to scaling phenomena are described. The presented concepts are exemplified by experimental data gathered on four representatives of molecular magnets.
    Acta Physica Polonica Series a 11/2013; 124(6):977. DOI:10.12693/APhysPolA.124.977 · 0.60 Impact Factor
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    ABSTRACT: A comprehensive study of magnetocaloric effect (MCE) and critical behaviour in the ferrimagnetic Mn2-pyridazine-[Nb(CN)8] molecular magnet under hydrostatic pressure is reported. The pressure-induced structural changes provoke the strengthening of magnetic interaction between Mn and Nb centres. Consequently, an increase of critical temperature Tc is observed from 43 K for a sample at ambient pressure (A) to 52.5 K for a sample under a pressure of 1.19 GPa (AHP). The magnetocaloric effect was determined by the magnetization measurements. The application of a hydrostatic pressure of 1.19 GPa causes a decrease in the maximum value of magnetic entropy change ΔS, which for AHP is equal to 4.63 J mol(-1) K(-1) (7.73 J kg(-1) K(-1)) at μ0ΔH = 5 T, while for A it is 5.36 J mol(-1) K(-1) (8.95 J kg(-1) K(-1)) for the same magnetic field change. The temperature-dependent parameter n obtained for AHP, describing the field dependence of MCE, is consistent with other critical exponents determined from magnetization measurements. The critical exponents allow us to classify AHP to the 3D Heisenberg universality class, similar to the case of the non-pressurized sample.
    Journal of Physics Condensed Matter 11/2013; 25(49):496012. DOI:10.1088/0953-8984/25/49/496012 · 2.22 Impact Factor
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    ABSTRACT: The critical behaviour of the three dimensional (3D) molecular magnet {[Fe-II(pirazol)(4)](2)[Nb-IV(CN)(8)]center dot 4H(2)O}(n) has been studied with the use of experimental techniques such as ac magnetometry and zero field mu SR spectroscopy. The sample orders magnetically below T-c=7.8 K. The measurements allowed to determine static exponents beta, gamma, and the dynamic exponent w. The resulting exponent values indicate that the studied system belongs to the universality class of the 3D Heisenberg model.
    Journal of Magnetism and Magnetic Materials 10/2013; 344:105-108. DOI:10.1016/j.jmmm.2013.05.041 · 2.00 Impact Factor
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    ABSTRACT: Unique two dimensional enantiopure cyanido-bridged {[Mn-II(R-mpm) (2)](2)[Nb-IV(CN)(8)]}center dot 4H(2)O and {[Mn-II(S-mpm)(2)](2)[Nb-IV(CN)(8)]}center dot 4H(2)O (1-S) (mpm = alpha-methyl-2-pyridine-methanol) ferrimagnets with T-C = 23.5 K were synthesized and characterized. They reveal natural optical activity (NOA) due to the chiral crystal structure, and magnetic optical activity (MOA) in the presence of an external magnetic field, with the strong enhancement in the magnetically ordered phase below T-C.
    Chemical Communications 06/2013; 49(60). DOI:10.1039/c3cc43195a · 6.72 Impact Factor
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    ABSTRACT: Cyanido-bridged high-spin {CoII[CoII(MeOH)3]8[WV(CN)8]6} (Co9W6) clusters revealing single-molecule magnet behavior were combined with 4,4′-bipyridine-N,N′-dioxide (4,4′-bpdo) linkers, giving unique H-bonded supramolecular {CoII9(MeOH)24[WV(CN)8]6}·4,4′-bpdo·MeOH·2H2O (1) chains and one-dimensional coordination {CoII[CoII(4,4′-bpdo)1.5(MeOH)]8[WV(CN)8]6}·2H2O (2) nanowires. The hydrogen-bonded chains of 1 are embedded within the three-dimensional supramolecular network stabilized by the series of noncovalent interactions between Co9W6 clusters, 4,4′-bpdo, and solvent molecules. The coordination nanowires 2, revealing an average core diameter of about 11 Å, are arranged parallel with the significant separation in the crystal structure, leading to a microporous supramolecular network with broad channels (12 × 12 Å) filled by methanol and water. Both 1 and 2 are stable only in a mother solution or an organic protectant, whereas they undergo the fast exchange of methanol ligands to water molecules during drying in the air. Synthesized materials preserve the magnetic characteristics of Co9W6 clusters with an effective ferromagnetic coupling, giving a ground-state spin of 15/2. For 2, the additional antiferromagnetic intercluster interactions are observed. Below 3 K, the frequency-dependent χM″(T) signals of 1 and 2 indicate the onset of slow magnetic relaxation. For 1, the relaxation time follows the Arrhenius law with an energy gap of Δ/kB = 10.3(5) K and τ0 = 4(1) × 10–9 s, which is consistent with single-molecule magnet behavior.
    Crystal Growth & Design 06/2013; 13(7):3036–3045. DOI:10.1021/cg400448x · 4.56 Impact Factor
  • Polyhedron 03/2013; 52:442-447. DOI:10.1016/j.poly.2012.08.053 · 2.05 Impact Factor