Jiri Tucek

Palacký University of Olomouc, Olmütz, Olomoucký, Czech Republic

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Publications (46)156.67 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: A chiral metal-organic framework exhibiting spin crossover (SCO) property, [Fe(II)(mptpy)2]·EtOH·0.2DMF (·solv), has been solvothermally synthesized through spontaneous resolution. It displays remarkable stability and two-step SCO at (Tc1 = 200 K) and above (Tc2 = 357 K) room temperature.
    Chemical Communications 03/2014; · 6.38 Impact Factor
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    ABSTRACT: Clustering of biocompatible magnetic iron oxide nanocrystallites (MIONs) is a synthetic strategy which improves magnetic manipulation, imaging, and sensing for biomedical applications. In this work we describe the synthesis of condensed clustered MIONs obtained through biomineralization and epitaxial aggregation in the presence of alginate at ambient conditions, mimicking the process that so far has been achieved only by nature, in iron-oxidizing bacteria. These condensed-type magnetic nanostructures exhibit higher magnetophoretic responses compared to other types of magnetic colloids and clustered systems. The soft environ mental conditions used for the synthesis of the magnetic nanosystems enables the alginate coating material to retain high drug loading ability for the doxorubicin molecule as well as strong binding proclivity for radionuclides. The strong binding of doxorubicin forms the physical basis to obtain magnetic nanocarriers, where the selective release of the drug occurs only under the action of external stimuli, such as remote magnetic hyperthermia or increased temperature (i.e., inflamed tissue). Furthermore, the strong binding proclivity of radionuclides facilitates in vivo SPECT imaging. The witnessed properties are obtained by using only ∼17 wt % alginate content in the magnetic superstructures; thus, very high saturation magnetization value is imparted to the condensed system, expressed in terms of the hybrid’s mass. In spite of the fact that the magnetic nanoassemblies are characterized by low hydrodynamic diameter, ∼45 nm, the transverse relaxivity reaches the remarkable value of 250 s−1 mM−1 Fe (for negative MION contrast agents of this size), a property that va+lidates the use of these nanostructures as effective MRI contrast agents.
    Chemistry of Materials 02/2014; · 8.24 Impact Factor
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    ABSTRACT: We present a simple molecular approach to control the lipophilic/hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 °C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations.
    Carbon. 01/2014; 70:279–286.
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    ABSTRACT: Lunar-type space weathering of airless bodies is associated with nanophase iron (npFe0) production in Fe bearing silicate minerals that is often responsible for observable changes of its reflectance spectra. A new method of controlled npFe0 production on olivine grains was developed in order to quantitatively evaluate spectral changes related to space weathering and presence of npFe0. Through a two-step thermal treatment a series of olivine samples with increasing concentration of iron nanoparticles on the grain surfaces was prepared. The grain size of the npFe0 particles was kept in the same range 5-20 nm). Magnetic methods were used to estimate npFe0 concentration. Compared to fresh olivine, treated samples exhibit the spectral characteristics of lunar type space weathering (darkening, shallowing of 1 µm olivine absorption band, and reddening) related to increasing presence of npFe0. From quantitative point of view, a logarithmic trend was found between spectral changes and npFe0 concentration. One sample with additional population of larger ~50 nm npFe0 particles follows the darkening and the 1 µm band shallowing trend, but does not fully follow the reddening trend. This is due to fact that the larger 40 50 nm sized) npFe0 particles do not contribute to the spectral slope change. The observed logarithmic trend between the spectral changes and the npFe0 concentration give constrains on time evolution of space weathering. In the case of constant micro impact, solar wind and cosmic radiation on a regolith, the npFe0 concentration increases linearly with time while spectral changes related to space weathering evolve logarithmically with time.
    10/2013;
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    ABSTRACT: A novel core-shell nanomaterial based on prussian blue (PB) coating on peculiar surface active maghemite nanoparticles (SAMNs), was developed. The synthetic process involves the direct crystallization of Fe(II)(CN)6(4-) onto the surface of SAMNs by simple incubation in water at controlled pH, demonstrating the presence of under-coordinated Fe(III) on nanoparticle surface. The coating reaction occurs in a narrow pH range and the synthetic procedure was optimized. The resulting SAMN@PB hybrid nanostructures were characterized by transmission and scanning electron microscopy, Mössbauer, UV-vis and FTIR spectroscopy and X-ray powder diffraction. The nanomaterial, characterized by high stability in alkaline media, behave as excellent electro-catalyst for hydrogen peroxide reduction. The stability of SAMN@PB hybrid has been investigated as a function of pH, showing excellent stability up to pH 9.0 and demonstrating the feasibility of SAMNs, superficially derivatized with prussian blue, to produce an efficient and extremely stable nanostructured material. This maghemite supported nanostructured prussian blue was applied to develop a sensor, based on a simple carbon paste electrode, which was able to catalyze the electro-reduction of hydrogen peroxide, in aqueous solutions, buffered at pH 7.0, at low applied potentials (0.0V vs. SCE).
    Biosensors & bioelectronics 08/2013; 52C:159-165. · 5.43 Impact Factor
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    ABSTRACT: Hierarchical assembly of Ti(iv)/Sn(ii)-doped SnO2 nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(iv) source is demonstrated, using SnCl2 as a tin precursor and Sn(ii) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(ii)-doped SnO2 on the titanate nanowires due to the insufficient oxidization of Sn(ii) to Sn(iv). Simultaneously, titanate nanowires are dissolved forming Ti(4+) species under the etching effect of in situ generated HF resulting in spontaneous Ti(4+) ion doping of SnO2 nanosheets formed under hydrothermal conditions. Compositional analysis indicates that Ti(4+) ions are incorporated by substitution of Sn sites at a high level (16-18 at.%), with uniform distribution and no phase separation. Mössbauer spectroscopy quantified the relative content of Sn(ii) and Sn(iv) in both Sn(ii)-doped and Ti(iv)/Sn(ii) co-doped SnO2 samples. Electrochemical properties were investigated as an anode material in lithium ion batteries, demonstrating that Ti-doped SnO2 nanosheets show improved cycle performance, which is attributed to the alleviation of inherent volume expansion of the SnO2-based anode materials by substituting part of Sn sites with Ti dopants.
    Nanoscale 08/2013; · 6.23 Impact Factor
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    ABSTRACT: MCM-41-supported nanoscale zero-valent iron (nZVI) was sytnhesized by impregnating the mesoporous silica martix with ferric chloride, followed by chemical reduction with NaHB4. The samples were studied with a combination of characterization techniques such as powder X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and Mössbauer spectroscopy, N2 adsorption measurements, transmission electron microscopy (TEM), magnetization measurements, and thermal analysis methods. The experimental data revealed development of nanoscale zero-valent iron particles with an elliptical shape and a maximum size of ∼80nm, which were randomly distributed and immobilized on the mesoporous silica surface. Surface area measurements showed that the porous MCM-41 host matrix maintains its hexagonal mesoporous order structure and exhibits a considerable high surface area (609m(2)/g). Mössbauer and magnetization measurements confirmed the presence of core-shell iron nanoparticles composed of a ferromagnetic metallic core and an oxide/hydroxide shell. The kinetic studies demonstrated a rapid removal of Cr(VI) ions from the aqueous solutions in the presence of these stabilized nZVI particles on MCM-41, and a considerably increased reduction capacity per unit mass of material in comparison to that of unsupported nZVI. The results also indicate a highly pH-dependent reduction efficiency of the material, whereas their kinetics was described by a pseudo-first order kinetic model.
    Journal of hazardous materials 07/2013; 261C:295-306. · 4.14 Impact Factor
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    ABSTRACT: We present the first direct evidence that reactant particle size determines the mechanism of thermally induced solid-state reactions and can be used as the tuner of the product crystal structure. This control of the polymorphous character of the products through the particle size of precursor is demonstrated upon following the process of isothermal decomposition of Prussian Blue at 350 uC in air. The reaction mechanism was studied by 57Fe Mo¨ssbauer spectroscopy, X-ray powder diffraction, magnetization measurements, and transmission and scanning electron microscopy. The decomposition of Prussian Blue nanoparticles (10–15 nm) gave preferential formation of c-Fe2O3 nanoparticles (10–20 nm), while Prussian Blue microcrystals (20–50 mm) afforded formation of b-Fe2O3 nanoparticles (50–70 nm). The final polymorphous composition of the iron(III) oxide product is thought to be driven by the different diffusion conditions for penetration of the reaction gas (oxygen) into the Prussian Blue crystals as well as release of the gas (dicyane) during the Prussian Blue decomposition. Therefore, the reactant particle size control provides a new method for the large-scale preparation of rare b-Fe2O3 nanoparticles.
    RSC Advances 07/2013; · 2.56 Impact Factor
  • Polyhedron 05/2013; · 1.81 Impact Factor
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    ABSTRACT: We report the first example of arsenite and arsenate removal from water by incorporation of arsenic into the structure of nanocrystalline iron(III) oxide. Specifically, we show capability to trap arsenic into the crystal structure of γ-Fe2O3 nanoparticles that are in-situ formed during treatment of arsenic-bearing water with ferrate(VI). In water, decomposition of potassium ferrate(VI) yields nanoparticles having core-shell nanoarchitecture with γ-Fe2O3 core and γ-FeOOH shell. High-resolution X-ray photoelectron spectroscopy and in-field 57Fe Mössbauer spectroscopy give unambiguous evidences that significant portion of arsenic is embedded in tetrahedral sites of γ-Fe2O3 spinel structure. Microscopic observations also demonstrate principal effect of As-doping on crystal growth as reflected by considerably reduced average particle size and narrower size distribution of the in-situ sample with embedded arsenic compared to the ex-situ sample with arsenic exclusively sorbed on iron oxide nanoparticle surface. Generally, presented results highlight ferrate(VI) as one of the most promising candidates for advanced technologies of arsenic treatment mainly due to its environmentally friendly character, in-situ applicability for treatment of both arsenites and arsenates, and, contrary to all known competitive technologies, firmly bound part of arsenic preventing its leaching back to environment. Moreover, As-containing γ-Fe2O3 nanoparticles are strongly magnetic allowing their separation from environment by application of external magnet.
    Environmental Science & Technology 03/2013; · 5.26 Impact Factor
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    ABSTRACT: Presence of artificially produced 60-nm metallic nanoparticles on olivine powder grains caused darkening and shallowing of absorption bands, but not reddening.
    03/2013;
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    ABSTRACT: Biogenic iron oxides have been collected from a water stream and subsequently magnetically modified using water-based magnetic fluid. Both natural and magnetically modified materials have been characterized in detail using wavelength dispersive X-ray fluorescence spectrometry, X-ray powder diffraction, Mössbauer spectroscopy, electron microscopy and BET surface area measurements. The natural material is composed of 2-line ferrihydrite, forming hollow microtubules—sheaths of Leptothrix ochracea, and detrital components. As a result of the ferrofluid modification, maghemite nanoparticles were identified on the surface of the treated material. The active surface area of the bulk, magnetically-modified sample was 148 m2 g−1. The magnetically modified material was tested as inexpensive magnetically responsive adsorbent for the removal of selected organic xenobiotics, namely organic dyes, from aqueous solutions. The observed maximum adsorption capacities ranged between 34.3 and 97.8 mg of dye per 1 g of adsorbent.
    International journal of Environmental Science and Technology 01/2013; · 1.84 Impact Factor
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    ABSTRACT: Olivines, a significant constituent of basaltic rocks, have the potential to immobilize permanently CO2 after it is injected in the deep subsurface, due to carbonation reactions occurring between CO2 and the host rock. To investigate the reactions of fayalitic olivine with supercritical CO2 (scCO2) and formation of mineral carbonates, experiments were conducted at temperatures of 35 °C to 80 °C, 90 atm pressure and anoxic conditions. For every temperature, the dissolution of fayalite was examined both in the presence of liquid water and H2O-saturated scCO2. The experiments were conducted in a high pressure batch reactor at reaction time extending up to 85 days. The newly formed products were characterized using a comprehensive suite of bulk and surface characterization techniques X-ray diffraction, Transmission/Emission Mössbauer Spectroscopy, Scanning Electron Microscopy coupled with Focused Ion Beam, and High Resolution Transmission Electron Microscopy. Siderite with rhombohedral morphology was formed at 35 °C, 50 °C, and 80 °C in the presence of liquid water and scCO2. In H2O-saturated scCO2, the formation of siderite was confirmed only at high temperature (80 °C). Characterization of reacted samples in H2O-saturated scCO2 with high resolution TEM indicated that siderite formation initiated inside voids created during the initial steps of fayalite dissolution. Later stages of fayalite dissolution result in the formation of siderite in layered vertical structures, columns or pyramids with a rhombus base morphology.
    Chemical Geology. 11/2012; s 332–333.
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    ABSTRACT: Biomimetic complexes are artificially engineered molecules that aim to reduce the structural complexity of biological systems in order to unveil the key electronic and structural factors relevant to a protein's function. In this work, a novel coordination compound () which mimics non-heme binuclear proteins was synthesized from the Schiff-base ligand HL = (E)-N'-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide. The crystal structure of showed that the intramolecular Fe-Fe distances (3.1-3.2 Å) were analogous to those found in non-heme binuclear ferric proteins. However, in , two methoxide groups act as bridging units for oxidized iron (Fe(3+)). Such a bridging motif is unprecedented in the biological realm. Magnetic susceptibility measurements demonstrated that is characterized by a singlet (S = 0) ground state and a very small magnetic coupling constant J (≪ -1 cm(-1)). The J value featured by differs considerably from the values observed in non-heme binuclear proteins in the oxidized form (-100 cm(-1) < J < -10 cm(-1)), which encompass oxo/hydroxo and carboxylate bridging residues. The singlet ground state of as well as the weak magnetic interaction between the two ferric cations was successfully predicted by density functional theory (DFT).
    Dalton Transactions 11/2012; · 3.81 Impact Factor
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    ABSTRACT: We present a new, easily scalable method for the deposition of nanocrystalline hematite photoelectrodes based on the spin-coating of a mixed solution containing tin(II) and iron(III) chlorides followed by thermal treatment. Our facile approach does not require any additional film-forming organic species and allows simple control of the photoelectrochemical performance of the electrode by adjusting the degree of tin doping. When annealed at 650 °C a strong increase in the water oxidation photocurrent is observed with increasing tin concentration. The maximum performance (0.45 mA cm−2 at 1.43 V vs. RHE) was found at the highest possible tin loading (20:100, Sn:Fe). The contrasting performance of electrodes annealed at 650 °C and 800 °C suggests different activation processes for dopant diffusion and activation. The doping of tin into the crystal structure of hematite thin films is directly evidenced by X-ray photoelectron spectroscopy and indirectly by changes in the intrinsic magnetic parameters (Morin temperature, Néel temperature) of the hematite films. The magnetization measurements thus represent a potential technique to quantify doping amounts in hematite.
    Journal of Materials Chemistry 10/2012; 22(43):23232-23239. · 5.97 Impact Factor
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    ABSTRACT: Core-shell hydrophilic superparamagnetic iron oxide (SPIO) nanoparticles, surface functionalized with either terephthalic acid or 2-amino terephthalic acid, showed large negative MRI contrast ability, validating the advantage of using low molecular weight and π-conjugated canopies for engineering functional nanostructures with superior performances.
    Chemical Communications 10/2012; · 6.38 Impact Factor
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    ABSTRACT: Fluorescent core–shell nanohybrids with the shells derived from carbon dots and cores differing in the chemical nature and morphology were synthesized. Hybrid nanoparticles combine fluorescence with other functionalities such as magnetic response on a single platform. These hybrids can be used in various bioapplications as demonstrated with labeling of stem cells.
    Journal of Materials Chemistry 07/2012; 22(32):16219-16223. · 5.97 Impact Factor
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    ABSTRACT: Hybrid magnetic drug nanocarriers are prepared via a self-assembly process of poly(methacrylic acid)-graft-poly(ethyleneglycol methacrylate) (p(MAA-g-EGMA)) on growing iron oxide nanocrystallites. The nanocarriers successfully merge together bio-repellent properties, pronounced magnetic response, and high loading capacity for the potent anticancer drug doxorubicin (adriamicin), in a manner not observed before in such hybrid colloids. High magnetic responses are accomplished by engineering the size of the magnetic nanocrystallites (∼13.5 nm) following an aqueous single-ferrous precursor route, and through adjustment of the number of cores in each colloidal assembly. Complementing conventional magnetometry, the magnetic response of the nanocarriers is evaluated by magnetophoretic experiments providing insight into their internal organization and on their response to magnetic manipulation. The structural organization of the graft-copolymer, locked on the surface of the nanocrystallites, is further probed by small-angle neutron scattering on single-core colloids. Analysis showed that the MAA segments selectively populate the area around the magnetic nanocrystallites, while the poly(ethylene glycol)-grafted chains are arranged as protrusions, pointing towards the aqueous environment. These nanocarriers are screened at various pHs and in highly salted media by light scattering and electrokinetic measurements. According to the results, their stability is dramatically enhanced, as compared to uncoated nanocrystallites, owing to the presence of the external protective PEG canopy. The nanocarriers are also endowed with bio-repellent properties, as evidenced by stability assays using human blood plasma as the medium.
    Small 05/2012; 8(15):2381-93. · 7.82 Impact Factor
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    ABSTRACT: Cyanobacteria pose a serious threat to water resources around the world. This is compounded by the fact that they are extremely resilient, having evolved numerous protective mechanisms to ensure their dominant position in their ecosystem. We show that treatment with nanoparticles of zerovalent iron (nZVI) is an effective and environmentally benign method for destroying and preventing the formation of cyanobacterial water blooms. The nanoparticles have multiple modes of action, including the removal of bioavailable phosphorus, the destruction of cyanobacterial cells, and the immobilization of microcystins, preventing their release into the water column. Ecotoxicological experiments showed that nZVI is a highly selective agent, having an EC(50) of 50 mg/L against cyanobacteria; this is 20-100 times lower than its EC(50) for algae, daphnids, water plants, and fishes. The primary product of nZVI treatment is nontoxic and highly aggregated Fe(OH)(3), which promotes flocculation and gradual settling of the decomposed cyanobacterial biomass.
    Environmental Science & Technology 02/2012; 46(4):2316-23. · 5.26 Impact Factor

Publication Stats

117 Citations
536 Downloads
2k Views
156.67 Total Impact Points

Institutions

  • 2004–2014
    • Palacký University of Olomouc
      • • Regional Centre of Advanced Technologies and Materials
      • • Department of Experimental Physics
      Olmütz, Olomoucký, Czech Republic
  • 2012
    • Academy of Sciences of the Czech Republic
      • Botanický ústav
      Praha, Hlavni mesto Praha, Czech Republic
    • University of Zanjan
      • Department of Chemistry
      Zanjān, Zanjan, Iran
    • Helmholtz-Zentrum Berlin
      Berlín, Berlin, Germany