This work describes, for the first time, the preparation of palladium nanoparticles supported in thermally-treated human hair. Human hair showed to be an efficient adsorbent of Pd2+ in aqueous media, reaching nearly 100% of adsorption from a 100 ppm solution. The thermal treatment of hair containing Pd2+ at 200 ºC under nitrogen atmosphere led to the formation of an N, S-containing material presenting 0.5 wt.% of palladium. The material was extensively characterized by elemental analysis (CHN and inductively coupled plasma optical emission spectroscopy (ICP OES)), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and Raman spectroscopies, and by thermogravimetry (TG), thermogravimetry coupled to mass spectrometry (TG-MS), scanning electron miscroscopy (SEM), transmission electron microscopy (TEM) and dispersive X-ray spectroscopy (EDS) analyses. It was possible to observe that the surface structure of hair was preserved during thermal treatment, presenting palladium nanoparticles with particle sizes of approximately 4 nm. This material was used as heterogeneous catalyst in a preliminary application in nitrobenzene reduction to aniline in aqueous medium using sodium borohydride.

A novel, fast, low-cost and scalable methodology to prepare stable magnetoliposomes (MGLs), without the use of organic solvents, is described. The concept of the work is based on the dual use of soy lecithin associated to a new liposome preparation methodology. Soy lecithin was used to coat the nanoparticles of magnetite (Fe3 O4 @lecithin) and for encapsulation of Fe3 O4 @lecithin (Lip-Fe3 O4 @lecithin). Liposomes with size less than 160 nm, polydispersity index of 0.25 and zeta potential of -41 mV, were prepared with the use of autoclave and sonication. The liposomal formulations containing magnetite and stigmasterol (Lip-Fe3 O4 @lecithin, Lip-Stigma and Lip-Stigma-Fe3 O4 @lecithin) were shown to be promising for the application as antibacterial. The liposomal formulation and magnetite were characterized by the following techniques: conventional and high-resolution transmission electron microscopy (TEM/HRTEM), energy-filtered transmission electron microscopy (EFTEM), proton nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), dynamic light scattering (DLS) and zeta potential. The Lip-Fe3 O4 @lecithin had a minimum inhibitory concentration (MIC) of 8.4 µg mL-1 in the presence of 200 Oe magnetic field against S. aureus.

This work describes the synthesis and characterization of two new compounds with ligand opy (N-(2-pyridyl)oxamate): the copper(II) precursor [Me4N]2[Cu(opy)2].5H2O and CoII CuII coordination polymer {[CoCu(opy)2]}n×4nH2O. This latter compound was obtained by reaction of [Me4N]2[Cu(opy)2].5H2O and CoCl2.6H2O in water. The heterobimetallic CoII CuII chain was characterized by elemental analysis, IR spectroscopy, thermogravimetry and magnetic measurements. Magnetic characterization revealed typical behavior of one-dimensional (1D) ferrimagnetic chain as shown in the curves of temperature (T) dependence of magnetic susceptibility (χM), in the form of χMT versus T, and dependence of magnetization (M) with applied field (H).

Um composto de fórmula [ttf]2[Cu(opba)]·H2O, com ttf = tetrathiafulvaleno e opba = orto-fenilenobis(oxamato), foi preparado e caracterizado. O complexo foi obtido por reação de metátese entre (ttf)3(BF4)2 e (Bu4N)2[Cu(opba)] em acetonitrila à temperatura ambiente. O espectro UV-Vis-NIR mostra a presença do radical cátion em duas formas, (ttf•+) e dímero (ttf•+)2. As propriedades de condutividade de [ttf]2[Cu(opba)]·H2O foram estudadas por espectroscopia de impedância (IS) e voltametria linear (LV) e mostram um comportamento típico de semicondutor. O espectro de EPR exibe duas linhas superpostas correspondentes aos spins eletrônicos de íons CuII e de radicais cátions ttf•+. As propriedades magnéticas (dc) mostram um valor do produto χMT na temperatura ambiente próximo ao esperado para três spins S = ½ desacoplados e um valor de 0.13 emu K mol-1 a baixas temperaturas (4 K). A curva do produto χMT versus T foi ajustada e o melhor modelo consiste de um termo para o dímero (ttf•+)2 (Bleaney-Bowers, resultando em J2 = -186 cm-1) e de um segundo termo relativo a uma cadeia antiferromagnética Cu···ttf •+ (J1 = -10.1 cm-1).

An oxamato-based compound of formula [ttf]2[Cu(opba)]·H2O, with ttf = tetrathiafulvalene and opba = ortho-phenylenebis(oxamato), has been prepared and characterized. The complex was obtained by metathesis from (ttf)3(BF4)2 and (Bu4N)2[Cu(opba)] in acetonitrile at room temperature. The UV-Vis-NIR spectrum reveals the presence of the radical cation in two forms, (ttf•+) and (ttf•+)2 dimer. The electronic transport properties of [ttf]2[Cu(opba)]·H2O were studied by impedance spectroscopy (IS) and linear voltammetry (LV), and show a typical semiconductor behavior. The EPR spectra exhibit two superposed lines corresponding to electron spins of CuII ions and ttf•+ radical cations. The dc magnetic properties show a room temperature value of the χMT product close to that expected for three uncoupled S = ½ spins and a value of 0.13 emu K mol-1 at low temperature (4 K). The χMT vs. T curve was fitted and the best model consists of a term for a (ttf•+)2 dimer (Bleaney-Bowers, leading to J2 = -186 cm-1) and a second term related to an antiferromagnetic {Cu···ttf•+} chain (J1 = -10.1 cm-1).

Um precursor inédito de sistemas magnéticos moleculares, [Fe(H2opba-i)(dmso)2]Cl (1), onde opba = orto-fenilenobis(oxamato) na forma tautomérica iminoálcool, foi obtido como produto da reação entre H4opba e FeCl3. Os dados de análise elementar, espectroscopias de absorção no infravermelho e Mössbauer e medidas magnéticas indicam que este precursor é constituído por uma mistura de isômeros trans (83%) e cis (17%). O valor de chiMT a 298 K (2,1 emu K mol-1) corresponde ao FeIII com estado de spin (S) entre 3/2 e 5/2. Cálculos teóricos (PBE/DZVP2) de trans- e cis-[Fe(H2opba-i)(dmso)2 ]+ mostram que ambos os isômeros têm spin S = 1/2 no estado fundamental e S = 3/2 para o trans e S = 5/2 para o cis no primeiro estado excitado. A combinação destes resultados leva a valores de chiMT de 0,375 emu K mol-1 e 2,3 emu K mol-1 a baixas e altas temperaturas, respectivamente, os quais são concordantes com os dados experimentais para 1.

A new precursor of molecule-based magnetic systems, [Fe(H2opba-i)(dmso)2]Cl (1), with opba = ortho-phenylenebis(oxamato) in an iminoalcohol tautomeric form, was obtained as a product from the reaction between H4opba and FeCl3. Data from elemental analysis, IR and Mössbauer spectroscopies and magnetic measurements indicate that this precursor is composed of a mixture of trans (83%) and cis (17%) isomers. The chiMT value at 298K (2.1 emu K mol-1) corresponds to FeIII with spin state (S) between 3/2 and 5/2. Theoretical calculations (PBE/DZVP2) of trans- and cis-[Fe(H2opba-i)(dmso)2 ]+ show that both isomers have spin S = 1/2 in the ground state and S = 3/2 for the trans and S = 5/2 for the cis in the first excited state. The combination of these results leads to chiMT values of 0.375 and 2.3 emu K mol-1, at low and high temperature respectively, which are in accordance with the experimental data for 1.

Neste trabalho, descrevemos a obtenção de dois novos compostos de cobre(II), ou precursores, (Pr-Rad)2[Cu(opba)].H2O (1) e (Bu-Rad)2[Cu(opba)].2H2O (2), onde opba é o ligante orto-fenilenobis(oxamato) e R-Rad+ são radicais cátions do tipo nitronil nitróxido. A partir destes compostos 1 e 2, foram sintetizados os dois novos magnetos moleculares [Pr-Rad]2[Mn2{Cu(opba)}3 ].3,3 DMSO.5H2O (3) e [Bu-Rad]2[Mn2{Cu(opba)}3 ].3DMSO.6H2O (4), respectivamente. As propriedades magnéticas dos precursores 1 e 2 mostram a presença de interações ferromagnéticas entre os radicais cátions e o cobre (II), na faixa de temperatura entre 20 e 300 K. Os magnetos moleculares 3 e 4 exibem magnetização espontânea com temperatura crítica, Tc, de 23 K e 24 K, respectivamente.

In this work, we describe the synthesis of two new copper(II) compounds, (Pr-Rad)2 [Cu(opba)].H2O (1) and (Bu-Rad)2[Cu(opba)].2H2O (2) where opba stands for ortho-phenylenebis(oxamato) and RRad+ are nitronyl nitroxide radical cations. From 1 and 2, two new molecule-based magnets [Pr-Rad]2[Mn2{Cu(opba)}3 ].3.3DMSO.5H2O (3) and [Bu-Rad]2 [Mn2{Cu(opba)}3].3DMSO.6H 2O (4) were obtained, respectively. The magnetic properties of precursors 1 and 2 show the presence of ferromagnetic interaction between the radical cations with copper(II), in the temperature range of 20-300 K. The magnets 3 and 4 exhibit spontaneous magnetization at critical temperatures, Tc, of 23 K and 24 K, respectively.