Publications by authors named "Laura C J Pereira"

This study aimed to develop multifunctional nanoplatforms for both cancer imaging and therapy using superparamagnetic iron oxide nanoparticles (SPIONs). Two distinct synthetic methods, reduction-precipitation (M) and co-precipitation at controlled pH (M), were explored, including the assessment of the coating's influence, namely dextran and gold, on their magnetic properties. These SPIONs were further functionalized with gadolinium to act as dual T1/T2 contrast agents for magnetic resonance imaging (MRI).

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Article Synopsis
  • Two heterometallic Cu(II)/Ni(II) coordination polymers were created in water using specific chemical reactions, resulting in distinct metal-organic architectures.
  • The structures of these polymers were analyzed using various techniques such as X-ray diffraction, FT-IR spectroscopy, and magnetic susceptibility measurements, revealing strong antiferromagnetic interactions between the copper ions.
  • The study showcases a simple self-assembly method for synthesizing these materials, potentially expanding the range of functional heterometallic coordination polymers.
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  • The study involves the synthesis of three mixed-valence barium iron fluorides (BaFeF series) using hydrothermal redox reactions, resulting in unique structural characteristics.
  • Each compound showcases different arrangements of FeF units: BaFeF features 1D infinite [FeFeF] double chains, BaFeF contains 1D [FeF] double chains, and BaFeF has a complex 3D framework with isolated FeF units.
  • Magnetic studies reveal that BaFeF undergoes an antiferromagnetic phase transition at ~11 K, while BaFeF exhibits canted antiferromagnetic ordering at ~32.5 K, indicating distinct magnetic properties influenced by their structural configurations.
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The complete structure revision of the PdGe ( = rare-earth metal) series revealed that YbPdGe is the only AlB ordered superstructure. Good-quality single crystals of this compound were successfully grown from molten indium flux, enabling accurate single-crystal investigations. YbPdGe crystallizes with the CeCoSi-type structure in the hexagonal space group 6/ (no.

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A new homoleptic Co(II) complex bearing two highly sterically congested 2-formiminopyrrolyl ,'-chelating ligands is reported, displaying slow relaxation of the magnetisation at zero static (DC) field. This compound shows a large value for the zero-field splitting (ZFS) parameter of -42.6(4) cm leading to a spin-reversal energy barrier of 85 cm.

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Inorganic glass is a transparent functional material and one of the few materials that keeps leading innovation. In the last decades, inorganic glass was integrated into opto-electronic devices such as optical fibers, semiconductors, solar cells, transparent photovoltaic devices, or photonic crystals and in smart materials applications such as environmental, pharmaceutical, and medical sensors, reinforcing its influence as an essential material and providing potential growth opportunities for the market. Moreover, inorganic glass is the only material that is 100% recyclable and can incorporate other industrial offscourings and/or residues to be used as raw materials.

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Polymeric platforms obtained by three-dimensional (3D) printing are becoming increasingly important as multifunctional therapeutic systems for bone treatment applications. In particularly, researchers aim to control bacterial biofilm on these 3D-platforms and enhance re-growing bone tissue, at the same time. This study aimed to fabricate a 3D-printed polylactic acid platform loaded with hydroxyapatite (HA), iron oxide nanoparticles (IONPs) and an antibiotic (minocycline) with tuneable properties and multistimuli response.

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Tetraphenylphosphonium salts of Co and Fe complexes with alkyl-substituted, -butyl (), and isopropyl () 2,3-thiophenedithiolate (α-tpdt) ligands, namely, TPP[Co(α--tpdt)] (), TPP[Fe(α--tpdt)] (-), TPP[Co(α--tpdt)] (), and TPP[Fe(α--tpdt)] () were prepared and characterized by cyclic voltammetry, single crystal X-ray diffraction, magnetic susceptibility measurements, and Fe Mössbauer spectroscopy. Compound and are isostructural with their Au and Ni analogues with a square-planar coordination geometry. Compound presents two polymorphs (-) both showing a Fe(III) bisdithiolene dimerization.

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Superparamagnetic iron oxide nanoparticles (SPIONs) have shown great potential in biomedicine due to their high intrinsic magnetization behaviour. These are small particles of magnetite or maghemite, and when coated, their surface oxidation is prevented, their aggregation tendency is reduced, their dispersity is improved, and the stability and blood circulation time are increased, which are mandatory requirements in biomedical applications. In this work, SPIONs were synthesized in air through a reduction-precipitation method and coated with four different polymers (Polyethylene glycol(PEG) 1000/6000 and dextran T10/T70).

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Early actinide ions have large spin-orbit couplings and crystal field interactions, leading to large anisotropies. The success in using actinides as single-molecule magnets has so far been modest, underlining the need for rational strategies. Indeed, the electronic structure of actinide single-molecule magnets and its relation to their magnetic properties remains largely unexplored.

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Three layered lanthanide hydroxides (LLHs), with the general formula Ln8(OH)20Cl4·nH2O (Ln = Tb (1), Ho (2), Er (3)), were prepared and magnetically characterized both as pure compounds and diluted within a yttrium diamagnetic matrix, LYH : xLn, LYH : 0.044Tb (1'), LYH : 0.045Ho (2'), and LYH : 0.

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The 5-substituted 2-aryliminopyrrolyl ligand precursors of the type 5-R-2-[ N-(2,6-diisopropylphenyl)formimino]-1 H-pyrrole (R = 2,6-Me-CH (1a), 2,4,6-Pr-CH (1b), 2,4,6-Ph-CH (1c; reported in this work), anthracen-9-yl (1d), CPh (1e; reported in this work)) were treated with K[N(SiMe)] in toluene to yield the respective 5-R-2-[ N-(2,6-diisopropylphenyl)formimino]pyrrolyl potassium salts 2a-e in high yields. The paramagnetic 15-electron Co(II) complexes of the type [Co{κ N,N'-5-R-NCH-2-C(H)═N(2,6-Pr-CH)}(Py)Cl] (3a-e; Py = pyridine) were prepared by salt metathesis of CoCl(Py) with the respective potassium salts 2a-e in moderate to good yields. When the CoCl(THF) precursor was combined with the in situ prepared sodium salt of ligand precursor 1b, the trinuclear complex [Co{κ N, N'-5-(2,4,6-Pr-CH)-NCH-2-C(H)═N(2,6-Pr-CH)}(μ-Cl)][(μ-Cl)Co(THF)] (4) was obtained in high yields.

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Gold and nickel bisdithiolene complexes with methyl and -butyl substituted thiophenetetrathiafulavalenedithiolate ligands (α-mtdt and α-tbtdt) were prepared and characterized. These complexes were obtained, under anaerobic conditions, as tetrabutylammonium salts. The diamagnetic gold monoanion (-Bu₄N)[Au(α-mtdt)₂] () and nickel dianionic species (-Bu₄N)[Ni(α-mtdt)₂] (x = 1,2) () were similar to the related non-substituted extended thiophenic-TTF (TTF = tetrathiafulvalene) bisdithiolenes.

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The crystal structure of (μ-oxo)hexakis(cyanoacetato-κO,O')(cyanoacetato-κO)diaquatriiron(III) cyanoacetic acid shows the formation of trinuclear complexes in a hydrogen-bond network that bonds all the molecules in a 3D arrangement. For this complex, within whose clusters the whole magnetic interaction takes place, Fe Mössbauer spectroscopy shows that the Fe cations are in the S=5/2 state in the temperature range 2-295K. The asymmetric broadening of the absorption peaks below 80K is consistent with strong antiferromagnetic interactions between the metal spins.

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Chitosan is a biopolymer widely used for biomedical applications such as drug delivery systems, wound healing, and tissue engineering. Chitosan can be used as coating for other types of materials such as iron oxide nanoparticles, improving its biocompatibility while extending its range of applications. In this work iron oxide nanoparticles (Fe3O4 NPs) produced by chemical precipitation and thermal decomposition and coated with chitosan with different molecular weights were studied.

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A tetravalent uranium compound with a radical azobenzene ligand, namely, [{(SiMe2 NPh)3 -tacn}U(IV) (η(2) -N2 Ph2 (.) )] (2), was obtained by one-electron reduction of azobenzene by the trivalent uranium compound [U(III) {(SiMe2 NPh)3 -tacn}] (1). Compound 2 was characterized by single-crystal X-ray diffraction and (1) H NMR, IR, and UV/Vis/NIR spectroscopy.

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Iron oxide nanoparticles (NPs) have been extensively studied in the last few decades for several biomedical applications such as magnetic resonance imaging, magnetic drug delivery and hyperthermia. Hyperthermia is a technique used for cancer treatment which consists in inducing a temperature of about 41-45 °C in cancerous cells through magnetic NPs and an external magnetic field. Chemical precipitation was used to produce iron oxide NPs 9 nm in size coated with oleic acid and trisodium citrate.

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(α-DT-TTF)2[Au(i-mnt)2] and (α-DT-TTF)2[Co(mnt)2] are two new salts of the donor α-dithiophene-tetrathiafulvalene with stable diamagnetic anions, both presenting a ladder structure of the donors organized in paired segregated stacks. The first one is isostructural with previously reported closely related compounds and presents a magnetic spin-ladder behavior with J∥= 83.5 K and J⊥ = 110.

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The magnetic properties of layered dysprosium hydroxides, both diluted in the diamagnetic yttrium analogous matrix (LYH:0.04Dy), and intercalated with 2,6-naphthalene dicarboxylate anions (LDyH-2,6-NDC), were studied and compared with the recently reported undiluted compound (LDyH = Dy8(OH)20Cl4·6H2O). The Y diluted compound reveals a single-molecule magnet (SMM) behavior of single Dy ions, with two distinct slow relaxation processes of the magnetization at low temperatures associated with the two main types of Dy sites, 8- and 9-fold coordinated.

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The Fe(III) complexes Fe(5-Br-qsal)2Ni(dmit)2·solv with solv = CH2Cl2 (1) and (CH3)2CO (2) were synthesized, and their structural and magnetic properties were studied. While magnetization and Mössbauer spectroscopy data of 1 showed a gradual spin transition, compound 2 evidenced an abrupt transition with a thermal hysteresis of 13 K close to room temperature (T1/2 ↓ ∼273 K and T1/2 ↑ ∼286 K). A similar packing arrangement of segregated layers of cations and anions was found for 1 and 2.

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The magnetic properties of the two uranium coordination compounds, [K(18c6)][U(OSi(O(t)Bu)3)4] and [K(18c6)][U(N(SiMe3)2)4], both presenting the U(III) ion in similar pseudotetrahedral coordination environments but with different O- or N-donor ligands, have been measured. The static magnetic susceptibility measurements and density functional theory studies suggest the presence of different ligand fields in the two compounds. Alternating-current susceptibility studies conducted at frequencies ranging from 95 to 9995 Hz and at temperatures in the 1.

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[U(Tp(Me2))2(bipy˙)], a uranium(III) complex with a radical bipyridine ligand which has magnetic properties with contributions from both the ligand and the metal, presents slow relaxation of the magnetisation at low temperatures, already under zero static magnetic field, and energy barriers slightly above the non-radical analogues.

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Iron oxide nanoparticles are having been extensively investigated for several biomedical applications such as hyperthermia and magnetic resonance imaging. However, one of the biggest problems of these nanoparticles is their aggregation. Taking this into account, in this study the influence of three different surfactants (oleic acid, sodium citrate and Triton X-100) each one with various concentrations in the colloidal solutions stability was analyzed by using a rapid and facile method, the variation in the optical absorbance along time.

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Article Synopsis
  • A series of four one-dimensional coordination polymers containing lanthanides (Gd(III), Tb(III), Dy(III), and Er(III)) were synthesized using picolinic and glutaric acids, showing isostructural characteristics with a previously reported compound.
  • The crystal structures feature pairs of lanthanide ions connected by carboxylic groups, forming a ladder-like arrangement within the polymers.
  • Magnetic studies indicated weak ferromagnetic interactions, classifying Gd(III), Dy(III), and Er(III) compounds as molecular magnets, while unique magnetic behaviors in these compounds arise from single ion effects and spin-lattice relaxation phenomena.
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The structure of the title compound, [Cu(C14H9NO4)(C12H8N2)] n , consists of zigzag polymeric chains along the c axis. The asymmetric unit contains one Cu(II) atom which is coordinated by one 2,2'-imino-dibenzoate ligand and a one phenanthroline unit. Two intra-molecular N-H⋯O hydrogen bonds occur.

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