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Chagas disease (CD), caused by the flagellate protozoan Trypanosoma cruzi, is one of the major public health problems in developing countries. Benznidazole (BNZ) is the only drug available for CD treatment in most countries, however, it presents high toxicity and low bioavailability. To address these problems this study used Zeolitic Imidazolate Framework-8 (ZIF-8), which has garnered considerable attention due to its potential applications, enabling the controlled delivery of drugs. The present work developed and characterized a BNZ@ZIF-8 system, and the modulation of BNZ release from the ZIF-8 framework was evaluated through the in vitro dialysis release method under sink conditions at different pH values. Moreover, the in vitro evaluation of cell viability and cytotoxicity by MTT assay were also performed. The dissolution studies corroborated that a pH sensitive Drug Delivery System capable of vectorizing the release of BNZ was developed, may leading to the improvement in the bioavailability of BNZ. The MTT assay showed that no statistically significant toxic effects occurred in the developed system, nor significant effects on cell viability.

An adsorbent-heater-thermometer nanomaterial, (ZIF-8,EuxTby)@AuNP, based on ZIF-8 (adsorbent), containing Eu3+ and/or Tb3+ ions (thermometer) and gold nanoparticles (AuNPs, heater) was designed, synthetized, characterized, and applied to controlled drug release. These composite materials were characterized as core-shell nanocrystals with the AuNPs being the core, around which the crystalline ZIF-8 has grown (shell) and onto which the lanthanide ions have been incorporated or chemosorbed. This shell of ZIF-8 acts as adsorbent of the drugs, the AuNPs act as heaters, while the luminescence intensities of the ligand and the lanthanide ions are used for temperature monitoring. This thermo-responsive material can be activated by visible irradiation to release small molecules in a controlled manner as established for the model pharmaceutical compounds 5-fluorouracil and caffeine. Computer simulations and transition state theory calculations shown that the diffusion of small molecules between neighboring pores in ZIF-8 is severely restricted and involves high-energy barriers. These findings imply that these molecules are uploaded onto and released from the ZIF-8 surface instead of being inside the cavities. This is the first report of ZIF-8 nanocrystals (adsorbents) containing simultaneously lanthanide ions as sensitive nanothermometers and AuNPs as heaters for controlled drug release in a physiological temperature range. These results provide a proof-of-concept that can be applied to other classes of materials, and offer a novel perspective on the design of self-assembly multifunctional thermo-responsive adsorbing materials that are easily prepared and promptly controllable.

We have reported the use of luminescent metal-organic frameworks for the development of a new alternative for UV-B radiation sensing. For obtaining the sensor, a doping sequence of Europium (1%, 2%, and 5%) was performed on the Zn(BDC)(dpNDI)(DMF) using solvothermal synthesis. The final material was characterized using powder X-ray diffraction (PXRD), Infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and spectroscopic investigation. The sensing phenomenon was studied from the controlled exposure of the Zn(BDC)(dpNDI):2% Eu coordinating polymer (without DMF in the structure) under UV-B radiation. Analysis of PXRD revealed that materials Zn(BDC)(dpNDI)(DMF): x% Eu (x = 1, 2 and 5%) show maintenance of the original MOF structure after incorporation of Eu3+ ion. The results of FT-IR indicate that Europium is connected in the compound by coordination bonds, evidenced by a detailed analysis of the symmetrical and asymmetric stretching of the ligand carbonyl group. The spectroscopic analysis for the material assisted in the realization of the correlation between the proposed structure and the environment occupied by the lanthanide ion. The sensing properties were studied for the compound Zn(BDC)(dpNDI):2%Eu mainly by the evaluation of the emission spectrum. The compound showed a significant decrease in its emission intensity after exposure to the UV-B radiation dose (0-9 J.cm-2), a phenomenon that has been explored in the composition of the sensor. The sensing mechanism was estimated through the analysis of ultraviolet-visible absorption spectrum and reflectance spectra in the determination of its direct and indirect band gap. Finally, the compound Zn(BDC)(dpNDI):2%Eu presented a versatile material for the development of tunable emitter material (exhibiting white light emission) and a promising dosimetric sensor of UV radiation light.

Benzene, toluene, ethylbenzene, and xylenes (BTEX), a class of volatile organic compounds, are harmful pollutants but also very important precursors in organic industrial chemistry. Among different approaches used for the BTEX treatment, the adsorption technology has been recognized as an efficient approach because it allows to recover and reuse both adsorbent and adsorbate. However, the selective adsorption of the components is the key factor for the efficiency of the process. With this view, calixarene-based materials are very promising due to the unique cavity-like structure of the ligand. An unprecedented coordination network based on calixarene of an interesting nanosheet-like morphology was prepared via a solvothermal layer method. This material showed selectivity for non-polar molecules with remarkable uptake of benzene (38.33 mmol/g). In addition, a simple and useful method of BTEX quantification, through 13 C NMR spectroscopy, is reported here for the first time.

In this work, a multifunctional system was developed in which antibacterial and luminescent properties were inserted into the matrix of hydroxyapatite (HAp) and its efficiency as a support for an antineoplastic drug was evaluated, aiming its application in the treatment of osseous diseases. The precipitation method was used for the synthesis of HAp, EuCl3 was used for the incorporation of Eu3+ as imaging agents, silver nanoparticles (AgNPs) with antimicrobial function were used, and a model of drug, 5-fluorouracil (5FU) was used. The developed material is characterized by several techniques, where crystalline peaks attributed to HAp were identified in the X-ray diffractogram, whereas the luminescence spectrum of the material presented emissions attributed to the Eu3+ ion. The identification and the uniform distribution of AgNPs, 5FU, and Eu3+ were confirmed by mapping the sample using energy-dispersive spectroscopy. The measurements indicated that 82% (±2.8) of 5FU was incorporated into the HAp matrix, and a gradual and increasing release of it as a function of time was observed. Assays carried out for different bacteria confirmed the antimicrobial action of the samples and the efficiency of the drug inserted into the matrix. An in vitro assay showed the bioactivity of the material and its potential to bind to living osseous tissue.

Herein we present a synthesis of ionic liquid imidazole-based cations with appended sulfone as terminals. These structures are investigated by RMN (2D), XDR, FTIR and Raman; and show high yield; purity; melting point 1.6 ms, quantum efficiency > 77%, narrow linewidth, a high degree of color purity and tunable emission. These excellent photophysical properties, associated with soft materials processability, make these materials potentially applicable in the development of luminescent films as OLEDs. We provide data for a detailed study of photoluminescence based on the theories developed by Malta-Judd-Ofelt. © 2018 Elsevier Science. All rights reserved

International audience; Golden grass is a vegetal fiber used in arts and crafts for its peculiar optical properties, namely, its shiny golden-like reflectivity. Since vegetal fiber structure is usually heterogeneous, complementary techniques have been used to understand the electronic properties of the external and core regions of golden grass fibers. The composition and dielectric function of the few nanometer-thick external surfaces has been investigated using X-ray photoelectron spectroscopy and energy loss spectroscopy (XPS-PEELS), while a comparison of vibrational and optical properties of the few-micron-thick external and fiber core regions was derived from Raman, optical, photoluminescence (PL) and photoacoustic (PAS) spectroscopies. Raman signature and valence-band distribution indicate that the internal and external parts of the fibers are made of some oxygen-depleted lignin-like carbonaceous material. Besides a plasmon peak at 21 eV, two main absorption bands at 3.7 eV and 8.2 eV have been identified as π−π* and σ−σ* electronic transitions at aromatic moieties. PL excitation and emission behavior confirm heterogeneous molecular structures at the core and external regions. Specular reflectance spectra calculated from the complex refractive index (derived from XPS-PEELS) do not explain the shiny golden-like aspect of golden grass, which may arise from diffuse reflectance within a collection of heterogeneous hollow fibers.

Two lanthanide complexes supported on MCM48 type silica have been synthetized to introduce a new concept of multi-stimuli responsive materials for anti-counterfeiting applications. This new technology provides a simple and secure way of storing information with different levels of security from biocompatible materials. Different luminescent patterns can be revealed and suppressed by external stimuli: addition and removal of a specific reagent (chemical stimulus) followed by UV exposure to reveal the characteristic luminescence of the material and heat treatment (physical stimulus) to suppress the red luminescence of the material. The chemical stimulus occurs from the complexation of β-diketone 4,4,4-trifluoro-1-phenyl-1,3-butadione (BTFA) in the Eu(H2O)nL–SiO2 (L = chelidamic acid or trimesic acid) printed hybrid and can be made via insertion of the ligand by soaking the label using a marker pen. Physical stimuli can occur through a portable heat gun. The complexation with BTFA enhances the Eu-luminescence through the antenna effect under exposure to common UV-light. Heating (∼145 °C) for a few seconds rapidly quenches the luminescence of the label and, after some cycles of heating–cooling, BTFA sublimates and leads to complete quenching of the red luminescence. The combination of chemical and physical stimuli provides two levels of security verification and unbreakable encryption.

Background: Acquired Immunodeficiency Syndrome (AIDS) is a major public health problem in the world. One of the highly effective drugs in anti-HIV therapy is efavirenz (EFZ), which is classified as Class II according to the Classification System of Biopharmaceuticals, presenting low solubility and high permeability, this being an obstacle related to the drug. Objective: This study aimed to obtain an innovative system based on EFZ and the Zeolitic Imidazolate Framework (ZIF-8) to use in the development of prolonged-release pharmaceutical forms that can circumvent this problem. Methods: The EFZ: ZIF-8 system was obtained by a selected ex-situ method due to its higher incorporation efficiency. Different characterization techniques corroborated the obtainment of the system, and drug release was analyzed by dissolution testing under sink conditions, the profiles being adjusted to some kinetic models. Results: At pH 1.2, the structure of ZIF-8 breaks down rapidly, releasing a large amount of drug within either 3h or short time. In the pH 4.5 and 6.8 medium, the EFZ release from the EFZ: ZIF-8 system obtained in ethanol was prolonged, releasing 95% of the drug in 24h at pH 4.5 and 75% medium at pH 6.8. Conclusion: It is evident that a promising pH-sensitive system was obtained using ZIF-8 as a novel carrier of EFZ intended for the alternative treatment of AIDS.

Polyaniline-decorated ZIF-8 nanoparticles (nPANI@nZIF-8) were easily synthesized and employed as a multifunctional system for the delivery of the antitumor drug 5-fluorouracil (5-FU). Because of the storage ability of the network ZIF-8, 68% of the total amount of the 5-FU drug was released at pH 5.2. The system exhibits absorption in the near-infrared (NIR) region and can be used in the photothermal therapy owing to the presence of nPANI, which has a strong NIR uptake. This absorption causes local hyperthermia by aiding in the diffusion of the drug molecules contained by the polymer into nPANI@nZIF-8/5-FU achieving a greater release of the 5-FU drug, about 80% activated by an NIR laser (λ = 980 nm). This hyperthermia reached about 70 °C (200 μL, 1 mg mL–1 nPANI@nZIF-8), which was directly proportional to the concentration of the material. Therefore, our work can aid in the construction of new chemo-photothermal platforms that may be employed in cancer therapy.

Mixed lanthanide-organic frameworks (MLOFs) are an interesting class of hybrid materials with unique luminescence properties. The detailed structure–property relationship studies are still insufficient and therefore, the precise design and synthesis of these materials are still required. With this view, MLOFs based on Gd3+, Eu3+ and Tb3+ ions and terephthalate were synthesized under solvothermal conditions, and the influence of the Eu3+ dopant concentration on the photophysical properties of Gd/Eu-1,4-BDC-MOFs was studied. Moreover, the effect of the excitation wavelength on color tuning in a Gd/Tb/Eu-1,4-BDC-MOF co-doped sample is also discussed here. Analyses of X-ray diffraction data indicated the Gd/Eu-1,4-BDC single phase formation in samples doped up to 7 mol% of Eu3+ ions. By increasing the europium content, a second crystalline phase was formed. Both crystalline phases with a metal–organic structure exhibited a red luminescence due to the characteristic 4f–4f transitions of Eu3+ ions. Although not observed in the X-ray diffraction patterns, most probably the second phase was also present in the sample with 7 mol% of Eu3+ ions, based on the results of photoluminescence. The Gd/Eu/Tb-1,4-BDC co-doped sample with 2.5 mol% of Eu3+ and 2.5 mol% of Tb3+ obtained as a single phase exhibited both red and green emissions due to the presence of Eu3+ and Tb3+ ions, respectively. Furthermore, the spectroscopic analysis indicated the energy transfer from Tb3+ to Eu3+, which allows the color tuning by changing the excitation wavelength.

Herein, we describe for the first time room temperature ionic liquids (RTILs) and imidazole-based cations with appended carboxylic acids as terminals, which are directly derived from the anhydrides. All structures were designed to meet the following criteria: (1) easy preparation (up-scaling into kg scale possible); (2) melting point of 1 ms, high quantum efficiency (47%), featured quantum yield (27%), and a remarkable sensitization efficiency to ILs of up to 83%, which suggests a synergistic coordination with lanthanide ions. We show that the materials obtained are potentially applicable for the construction of light-emitting electrochemical cells, owing to the properties of their basic components, including ionic liquids (with high electrical conductivity and a similar structure to liquid crystals) and lanthanide ions (which have unprecedented photophysical properties).

Analysis of gunshot residues (GSR) is a vital point of interest in forensic chemistry. GSR analysis is very well established, but there is still a lack of methodology to identify GSR obtained from lead-free or ‘non-toxic ammunition’ (NTA). To identify GSR from NTA, we have proposed the incorporation of luminescent markers to provide an optical and chemical signature to GSR. Furthermore, the luminescent markers can open up prospectives for ammunition encoding by adjusting their composition. Herein, we report the distinction among GSR particles containing different MOF-based markers by analyzing their organic fractions using near-infrared hyperspectral imaging (NIR-HSI) together with multivariate analysis (MCR-ALS). The method has been proven to be effective, non-destructive and fast in distinguishing marked GSR. It is possible to detect and correctly identify 72.2% of the samples, and all cases of misclassification are related to slight amount of material collected (8.3%) or confusion caused by one of the markers (19.4%). The study is developed in a forensic context of GSR analysis; however, the methodology described here is excellent and can be extrapolated to other applications that require distinguishing MOFs with different ligands.

In this work, reduced Titania (TiO2−x) was obtained by laser ablation of commercial rutile TiO2 powder dispersed in N,N-dimethyl formamide (DMF) using a pulsed Nd:YAG (Neodymium-doped Yttrium Aluminium Garnet) laser (532 nm, 10 ns, 10 Hz). It was observed that DMF solvent was able to promote change in the optical band gap of commercial TiO2 (P25). The Ultraviolet–Visible (UV–vis) absorption measurement showed a shoulder in the infrared region with maximum at 690 nm, characteristic of reduced metal oxide. The electron paramagnetic resonance (EPR) measurements confirmed the presence of oxygen vacancies by the characteristic signal in g = 2.002 g and more intense than water-reduced oxide commonly obtained in other works. The X-ray diffraction (XRD) results show the same crystalline phase to P25 and small shifts due to presence of vacancy’s distorting the TiO2 structure. Scanning electron microscopy (SEM) image have shown surface coalesced particles in comparison to commercial P25, agreeing with nitrogen adsorption measurements which indicated a decrease in the surface area from 10.6 to 6.9 m2/g. The photothermal conversion properties was investigated and the reduced TiO2 samples showed higher temperatures when excited with a laser 785 nm wavelength in function of the strong absorption band and higher vacancy’s concentration.

We report in this work, a new method for the determination of captopril by differential pulse voltammetry using a glassy carbon electrode modified with a copper metal-organic framework (H-Kust-1 or Cu3(BTC)2 or Cu-BTC), immobilized on the surface by a copolymer of acrylamide and sodium acrylate. This compound is detected by the formation of a copper(II)-captopril complex that is observed in an oxidation potential at ca. +0.28 V vs. Ag/AgCl. A linear dynamic range is obtained for a captopril concentration of 0.5 μM to 7.0 μM and the voltammetric response is highly reproducible within 3.52 % error. The sensitivity of 9.71±0.37 nA μM−1 and the limit of detection of 0.20±0.01 μM make this methodology highly applicable for practical applications. The determination of captopril in a commercial pharmaceutical sample showed a recovery of 93.3 %.

Luminescent materials have been widely studied due to the increasing number of applications in catalysis, biosensors and electro-optical devices. In this sense, the improvement of luminescent efficiency has been sought and several strategies have been proposed. In this work, experimental and theoretical approaches were used to achieve and understand the improvement of luminescent efficiency of lanthanide organic frameworks through a heating process. In this study, [Eu 2 (MELL)(H 2 O) 6 ] (EuMELL) was synthesized and characterized by scanning electron and fluorescence microscopies, thermogravimetric analysis, powder X-ray diffraction and photoluminescence techniques. In parallel, theoretical simulations of the material in solid phase were carried out using semiempirical approaches. The comparison between experimental and theoretical results indicated that the more accurate structure was calculated using the Sparkle/PM3 model. The temperature effects on the structure as well as the photophysical properties were evaluated by measurements in situ heating and compared to theoretical simulations using the Sparkle/PM3 geometry. The excellent agreement between the computational and experimental results in this study opens up a series of possibilities for studying other systems, particularly when structural details are not easily available. Moreover, that the controlled heating contributes to improve its the quantum efficiency by approximately 45%, suggesting that this approach can be a valuable tool for technological applications.

A multifunctional smart supramolecular platform based on a lanthanide-organic hydrogel is presented. This platform, which provides unique biocompatibility and tunable optical properties, is synthesized by a simple, fast, and reproducible eco-friendly microwave-assisted route. Photoluminescent properties enable the production of coated light-emitting diodes (LED), unique luminescent barcodes dependent on the excitation wavelength and thin-films for use in tamper seals. Moreover, piroxicam entrapped in hydrogel acts as a transdermal drug release device efficient in inhibiting edemas as compared to a commercial reference.

The incorporation of drugs in biodegradable polymeric particles is one of many processes that controllably and significantly increase their release and action. In this paper, we describe the synthesis and physicochemical characterization of ZnBDC-MOF + doxorubicin (DOXO@ZnBDC) and the system's effectiveness in the sustained release of the drug doxorubicin. An experimental and theoretical study is presented of the interaction between the [Zn(BDC)(H2O)2]n MOF and the drug doxorubicin (DOXO). The synthesis was characterized by elemental analysis and X-ray powder diffraction (XRPD). The experimental incorporation was accomplished and analyzed by Fourier transform infrared spectroscopy (FTIR), XRPD and UV–Vis (ultraviolet–visible) spectrophotometry. Based on an analysis of the doxorubicin release profile, our results suggest that the drug delivery system showed slower release than other systems under development. Studies of cytotoxicity by the MTT method showed good results for the system developed with antineoplastic doxorubicin, and together with the other results of this study, suggest the successful development of a MOF-based drug delivery system.

Matrizes de hidroxiapatita (HAp) dopadas com os ions lantanideos Eu3+, Ce3+ e Gd3+, [Ca10-xLnx(PO4)6(OH)2], foram obtidas pelo metodo da precipitacao com o objetivo de estudar suas propriedades fotofisicas. A partir de analises de Microscopia Eletronica de Varredura observou-se que amostras dopadas com ions lantanideos (Ln3+) apresentaram similaridade com a morfologia da HAp pura, por outro lado nos difratogramas de Raios X a partir do refinamento Rietveld verificou-se que a matriz aparece como fase majoritaria (≈ 70%) enquanto (≈ 30%) de uma fase secundaria de tricalcio fosfato (TCP) foi conferida em funcao das diferentes dopagens. Isotermas de adsorcao obtidas pela tecnica BET indicaram que todos os materiais sintetizados sao classificados como mesoporosos. Os espectros de emissao dos materiais exibem bandas caracteristicas dos ions Ln3+ incorporados a estrutura da matriz em 573 nm (5D0→F0), 600 nm (5D0→F1), 628 nm (5D0→F2), e 698 nm (5D0→F4) para HAp/Eu, 337-360 nm (5d→4f) para HAp/Ce e em 425 nm para HAp/Gd. Palavras-chave: Hidroxiapatita; Composito; Luminescente; Biomaterial; Propriedades.

We have found that monosodium glutamate, a common food additive, combines with neodymium(III) chloride to form a gel-like luminescent material. Preliminary rheology tests suggest that arrested phase separation causes the material’s gel behavior at high test frequencies. Luminescence spectra showed not only the expected Nd3+ emissions (upon 582 nm excitation) but also a broad emission in the infrared with maximum on 980 nm (upon 289 nm excitation), preliminarily assigned to a matrix effect.

Calix[n]arene-based coordination networks are an emerging class of materials with intriguing properties resulted from the presence of the cavity-like structure of the macrocycle and metallic nodes. In this work, four novel luminescent materials based on calix[4]arene-carboxylate and lanthanides (Eu3+ and Tb3+) were prepared by two synthetic approaches, solvothermal (CDA-Eu-ST) and slow diffusion (CDA-Eu-RT, CDA-Tb-RT, CTA-Tb-complex) methods. The coordination networks were characterized by PXRD, FTIR, SEM and solid-state photoluminescence, and the results indicated the formation of two different CDA-Eu-structures governed by the synthesis parameters. Single-crystal X-ray diffraction of CTA-Tb-complex revealed the formation of a new dinuclear complex of calix[4]arene-tetracarboxylate containing Na+ and Tb3+ coordinated within the lower rim of the molecule. Preliminary studies showed that CDA-Eu-RT was capable of selectively sensing Fe3+ ions in water via quenching the luminescence, demonstrating the possibility of using calix[4]arene-based platforms as efficient luminescent sensors.

We have synthesized new luminescent coordination polymers using 4,4׳-sulfonyldibenzoic acid (H2SDA) and several lanthanide ions by open crystallization in DMF. Three different 1-D structures were obtained, as determined by single-crystal X-ray diffraction: [La(η2-NO3)(μ-SDA)(DMF)3]n (1), [Sm(η2-NO3)(μ-SDA)(DMF)2·2DMF]n (3), [Ln(η2-NO3)(μ-SDA)(DMF)2·DMF]n (Ln = Eu (4), Dy (5), Ho (6), Er (7), Tm (8) and Lu (9)). A 2-D structure, [Er2(η2-SDA)3(DMF)(H2O)3·2DMF]n (10), was also obtained. The measured photophysical properties of these compounds seem to be interesting for applications (high lifetime, narrow line width and high degree of color purity). In addition, emission spectra, spontaneous emission coefficients (Arad and Anrad), and intensity parameters (Ω2 and Ω4), from spectroscopic data of Eu3+, were used to evaluate crystal stabilities. Differences in the spectra acquired before and after DMF removal clearly reflected the changes taking place in the ion environment.

Novel mixed-metal coordination polymers (CPs) based on Pb1−xEux–BDC (x = 0.05, 0.10, 0.25, 0.50 and BDC = 1,4-benzenedicarboxylic acid) are reported. The materials display different coordination structures as the Pb : Eu metal ratio is modified. Whereas for x 0.25 the samples are isotypical with [Eu2(BDC)3(H2O)4], as shown by powder (including Rietveld analysis) and single-crystal X-ray diffraction. The unique Pb0.75Eu0.25–BDC compound displays a mixture of both crystalline phases with the highest emission quantum yield value reported for luminescent CPs based on Pb(II), 69 ± 7%. Site-selective excitation using a common Xe lamp permits the detailed study of the two Eu3+ local sites, illustrating how powerful the Eu3+ luminescence is as a local probe spectroscopic tool.

Here we report a new synergic strategy for the synthesis of metal-organic frameworks (MOFs), the sonoelectrochemical method. The metal-organic framework HKUST-1 [Cu 3 (BTC) 2 (H 2 O) 3 ] n was successfully prepared by using this approach. Structural and morphological properties of HKUST-1 were studied and results compared with those obtained for the same material synthesized via a conventional solvothermal method. The sonoelectrochemical approach allowed the preparation of powder samples with nanosized characteristics, high yields and in a short time. Furthermore, we confirmed that this route worked well for the synthesis of others MOFs, such as ZIF-8 and MIL-53. Such simple and practical strategy may allow the large-scale production of MOFs, which is of great interest for industrial applications.

The use of layered double hydroxides associated with biologically active molecules is becoming a promising alternative in the development of drug delivery systems that may be applied to drug therapies for different diseases. Efavirenz is an antiretroviral belonging to class II of the biopharmaceutical classification system (low solubility, high permeability). Due to its low aqueous solubility, absorption problems occur in the gastrointestinal tract and, consequently, inadequate oral bioavailability. In this paper, the association between efavirenz and CaAl-layered double hydroxide was obtained by stirring in an acetonic solution until complete evaporation of the solvent. The hybrid material obtained was characterized by X-ray diffraction, differential scanning calorimetry and fourier transform infrared spectroscopy. It was observed that in systems containing up to 30 % of efavirenz, the drug became a molecule with amorphous characteristics and lost its crystalline character. This phenomenon can be demonstrateby the absence of the drug in crystalline plane diffractograms, as well as the absence of its melting point in thermal analysis. In the release test, these systems have been successful in increasing solubility. The system carrier-drug with 30 % of efavirenz was more promising with an increase of 558 % of soluble drug, compared to the drug alone. In antiproliferative activity on human macrophage cell lines, it was observed that the isolate efavirenz presented an IC50 value of 15.71 mg ml−1, while the system carrierdrug with 30 % of efavirenz showed an IC50 value of 20.83 mg ml−1, demonstrating that efavirenz in association with a CaAl-layered double hydroxide provided a reduction in drug toxicity.

This work reports the influence of experimental parameters (pH and counter-ion) in the synthesis of the 1D coordination polymer [Cu(IDA)(H2O)2]n (IDA = iminodiacetate), named here Cu-IDA. Copper-manganese bimetallic coordination polymers were also obtained by isomorphic replacement into Cu-IDA structure, with different molar ratio of Cu2+ and Mn2+ ions, denoted here as Cu/Mn-IDA (0.9/0.1; 0.7/0.3 and 0.5/0.5). New coordination polymers are isostructural to Cu-IDA and amounts of manganese atoms inserted into crystalline structure were evaluated by single-crystal X-ray diffraction and Rietveld refinement. All coordination polymers obtained were also characterized by infrared absorption spectroscopy and thermogravimetric analysis. Homometallic and bimetallic compounds were evaluated as catalysts for Baylis-Hillman reaction with yields and reaction times comparable or superior to those in the literature. Compounds containing manganese cations shows higher catalytic performance, especially Cu/Mn-IDA (0.9/0.1) with yield 91% in 5 hours of reaction. Results also indicate an important role played by the metallic centre in the catalytic mechanism.

One 3d-4f coordination compound was synthesized by reaction between cucurbit[6]uril samarium and copper chlorides with molecular formula [Sm2Cu2(C36H36N24O12)Cl10] (H2O)26. Upon heating, the compound undergoes a reversible colour change due to a solid-to-solid phase transition of the [CuCl4]2− anions. The powder diffraction and luminescence spectroscopy suggest small changes in the structure during the heating/cooling process.

Colon cancer is one of the world’s most deadly diseases. Because of its internal location, it is necessary to obtain faster and more efficient diagnostic tools for this organ site. In this context, we studied the development of new luminescent nanoprobes (LNPs) as an alternative diagnostic apparatus for detecting this disease. The nanoparticles examined herein are lanthanide-doped sodium yttrium fluoride (NaYF4:Ln) and have shown to be promising as investigative devices. However, significant problems with the use of LNPs are the lack of biocompatibility and the targeting of the system to tumor regions. One of the strategies to bypass these problems is to increase of the particle lipophilicity modifying their surfaces with organic compounds that present high similarity to the biological system. In this work, we synthesized six new materials for use in bioimaging techniques obtained from the combination of nanoparticles of NaYF4:5%Eu with organic aromatic compounds covalently bonded. The materials were characterized structurally and morphologically using XRD and TEM, techniques, which showed the identification of the crystallographic phase β-NaYF4:5%Eu and its nanometric size (particles smaller than 50 nm). The conjugation process was confirmed by FT-IR spectra analysis and from the TGA profile. Excitation and emission spectra allowed the evaluation of the optical properties of the synthesized compounds. The interaction and cellular uptake was confirmed when HT-29 colon cancer cells were exposed to LNPs, indicating that the developed system has promising applications in bioimaging procedures.

An electrochemical sensor based on a gold-copper metal-organic framework immobilized on the surface of glassy carbon electrode has been developed for the electrocatalytic oxidation and determination of glutathione. Gold nanoparticles were incorporated into copper-1,3,5-benzenetricarboxylate and the composition and structure of the resulting nanocomposite (Au@Cu-BTC) were verified by transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffractometry, scanning electron microscopy and Fourier transform infrared spectroscopy. Cyclic and square wave voltammetric studies of the electrochemical behavior of glutathione at the modified electrode showed that the incorporation of gold particles increased the conductivity of Cu-BTC. Glutathione was detected by the formation of a Cu (II)-glutathione complex and its subsequent oxidation at ca. + 0.25 V vs. Ag/AgCl. The proposed methodology exhibited a low limit of detection (0.30 μmol L−1) and a wide linear dynamic range (1–10.0 μmol L−1) with good sensitivity (0.89 ± 0.02 μA μmol L―1) and repeatability (2.14 %). The high recovery (98.2 %) obtained in the analysis of a dietary supplement renders this new approach very attractive for the analytical determination of glutathione in commercial samples, particularly if the technique is extended to commercially produced screen-printed electrodes.

A mixed lanthanide beta-diketonate complex of molecular formula [Eu0.45Tb0.55(btfa)(3) (4,4'-bpy)(EtOH)] (btfa(-) = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate; 4,4'-bpy = 4,4'-dipyridyl; EtOH = ethanol) was synthesized and its structure was elucidated by single crystal X-ray diffraction. The temperature dependence of the complex emission intensity between 11 and 298 K is illustrated by the Commission Internacionale l'Eclairage (CIE) (x,y) color coordinates change within the orange-red region, from (0.521, 0.443) to (0.658, 0.335). The existence of Tb3+-to-Eu3+ energy transfer was observed at room temperature and as the complex presents a relatively high emission quantum yield (0.34 +/- 0.03) it was doped in a 4,4'-bis(carbazol-9-yl) biphenyl (CBP) organic matrix to be used as emitting layer to fabricate a white organic light-emitting diode (WOLED). Continuous electroluminescence emission was obtained varying the applied bias voltage showing a wide emission band from 400 to 700 nm. The white emission results from a combined action between the Eu3+ and Tb3+ peaks from the mixed Eu3+/Tb3+ complex and the other organic layers forming the device. The intensity ratio of the peaks is determined by the layer thickness and by the bias voltage applied to the OLED, allowing us to obtain a color tunable light source. (C) 2014 Elsevier B. V. All rights reserved.

The increasing demand for multifunctional materials for use in several application fields has been encouraging research into luminescent hybrid materials. These have the advantage of combining features of both organic and inorganic matter, which can be tailored to enhance emission conditions. This work aims to elucidate structural/luminescence relations of Eu3+:siloxane–poly(methyl methacrylate) hybrid materials. Polymer content was evaluated through characterization of samples with increasing polymer/Si molar ratios. Results showed that the sample with the highest amount of polymer in its composition, PMMA8, had optimized emission features on account of the larger number of carbonyl groups available for Eu3+ coordination. This enhancement is evidenced by the quantum efficiency ( q ) and lifetime ( τ e x p ) values, which were considerably higher ( q = 24.7% and τ e x p = 0.62 ms) for PMMA8 hybrid than for the other samples. Thus, the hydrophobic polymer reduced the interaction of dopant ions to hydroxyl quenching groups and led to better dispersion, minimizing ion–ion energy transfer.

New porous composites LnBDC@AC (AC = Activated carbon, Ln = Eu and Gd and BDC = 1,4-benzenedicaboxylate) and CB[6]@AC (CB[6] = Cucurbit[6]uril) were obtained using hydrothermal route. The LnBDC and CB[B] are located inside the pore of the carbon materials as was observed in SEM-EDS, XRPD and FT-IR analysis. Porosimetry analysis showed values typically between AC and LnBDC material, with pore size and surface area, respectively, 29,56 A and 353.98 m2g-1 for LnBDC@AC and 35,53 A and 353.98 m2g-1 for CB[6]@AC. Both materials showed good absorptive capacity of metil orange (MO) and methylene blue (MB) with selectivity as a function of pH. For acid pH, both materials present selectivity by MB and alkaline pH for MO, with notable performance for CB[6]@AC. Additionally, europium luminescence was used as structural probe to investigate the coordination environment of Eu3+ ions in the EuBDC@AC composite after adsorption experiment.

Correction for ‘MOF@activated carbon: a new material for adsorption of aldicarb in biological systems’ by Carlos Alberto Fernandes de Oliveira et al., Chem. Commun., 2013, 49, 6486–6488.