Barbara Sieklucka

Jagiellonian University, Cracovia, Lesser Poland Voivodeship, Poland

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Publications (126)435.73 Total impact

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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; 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; 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 · 5.93 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 · 6.38 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 · 6.38 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
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    ABSTRACT: The incorporation of guanidinium ions (Hgua(+)) in Cu(II)-M(V) systems results in the formation of two isostructural coordination polymers (Hgua)Cu(II)[M(V)(CN)(8)], M = W (); Mo (), which reveal a double-layered structure separated by guanidinium ions. The magnetic measurements reveal long range magnetic ordering with critical temperatures of 32.8 and 27.5 K for and , respectively. Moreover, both assemblies exhibit hysteresis loops with coercive fields of 300 Oe for and 50 Oe for , and a spin-flip transition around 120 Oe.
    Dalton Transactions 02/2013; 42(14). DOI:10.1039/c2dt32397d · 4.10 Impact Factor
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    ABSTRACT: Which way to choose? The trimetallic cyanide-bridged Fe(6) Co(3) W(6) cluster serves as a molecular platform for two cooperating electron transfer channels, W(V) -CN-(HS) Co(II) ⇄W(IV) -CN-(LS) Co(III) and W(V) -CN-(HS) Fe(II) ⇄W(IV) -CN-(HS) Fe(III) . {Co(II) (3) Fe(II) (6) [W(V) (CN)(8) ](6) (MeOH)(24) }⋅x MeOH has a first-order unique spin transition with thermal charge-transfer-induced spin transition and spin bistability that is due to a specific distribution of Co and Fe sites.
    Angewandte Chemie International Edition 01/2013; 125(3). DOI:10.1002/anie.201208023 · 11.34 Impact Factor
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    ABSTRACT: The novel layered {CoII 3(2,29-bpdo)4(H2O)4[WV(CN)8]2}?8H2O (1) network (2,29-bpdo = 2,29-bipyridine- 1,19-dioxide) is built of 2-D corrugated cyanide-bridged brick-wall skeletons parallel to the bc crystallographic plane. The coordination of chelating 2,29-bpdo to Co(II) gives 7-membered coordination rings. Magnetic and heat capacity measurements performed on monocrystalline samples reveal ferromagnetic ordering below TC of 6 K. Magnetic anisotropy of the ordered phase is represented by the easy axis oriented in the ac crystallographic plane. Bulk magnetic anisotropy is confronted with a local anisotropy of Co complexes: a strong axial anisotropy of trans,cis,cis-[CoII(m-NC)2(H2O)2(2,29-bpdo)] moieties represented by gx (2) = 2.06, gy (2) = 2.95 and gz (2) = 7.30, and a planar anisotropy of trans,cis,cis- [CoII(m-NC)2(2,29-bpdo)2] represented by gx (3) = 5.40, gy (3) = 4.82 and gz (3) = 2.28, determined by CASSCF/ RASSI/SINGLE_ANISO ab initio calculations. The experimental data are explained by the molecular field simulation of the magnetic structure using the above theoretical data.
    CrystEngComm 01/2013; 15(13):2378. DOI:10.1039/C2CE26387D · 3.86 Impact Factor
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    ABSTRACT: In this paper magnetic properties of hybrid inorganic-organic compound {[FeII(pyrazole)4]2[NbIV(CN)8]•4H2O}n are presented. This is a three dimensional molecular magnet with well localized magnetic moments, which make it a suitable candidate for testing magnetic models. In order to characterize the magnetic properties of the above compound we performed the AC/DC magnetometry in the range 0-5 T. The special attention was paid to the phase transition at 7.9 K. The study in magnetic field supports magnetic ordering below 7.9 K.
    The European Physical Journal Conferences 01/2013; DOI:10.1051/epjconf/20134014002
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    ABSTRACT: Wo soll es hingehen? Der trimetallische Cyanid‐verbrückte Fe6Co3W6‐Cluster beherbergt zwei kooperierende Elektronentransferkanäle, WV–CN–HSCoII WIV–CN–LSCoIII und WV–CN–HSFeII WIV–CN–HSFeIII. {CoII3FeII6[WV(CN)8]6(MeOH)24}⋅x MeOH ist durch einen thermischen ladungstransferinduzierten Spinübergang erster Ordnung charakterisiert und zeigt Spinbistabilität, die von einer spezifischen Verteilung der Co‐ und Fe‐Zentren hervorgerufen wird.
    Angewandte Chemie 01/2013; 125(3). DOI:10.1002/ange.201208023