Carla D. Nunes

MCM-41 functionalized with bipyridyl groups and its use as a support for oxomolybdenum(VI) catalysts

The ordered mesoporous silica MCM-41 was covalently grafted with (3-chloropropyl)trimethoxysilane. Chloro substitution by the anion [4-CH2-4′-Me-2,2′-bipyridine]− gave a ligand-silica containing ca. 0.3 mmol bipyridyl groups per gram. Powder X-ray diffraction and nitrogen adsorption–desorption analysis demonstrated that the textural characteristics of the support were preserved during the grafting experiments and that the channels remained accessible, despite sequential reductions in surface area, pore volume and pore size. The coupling reactions were monitored by 29Si MAS NMR and 13C CP MAS NMR spectroscopy. Bipyridyl-functionalized MCM-41 exhibits a high encapsulating ability, as evidenced by its interaction with a dichloromethane solution of MoO2Cl2(THF)2. A material with a metal loading of 8.3 mass% was obtained. Molybdenum K-edge EXAFS analysis could not substantiate the formation of a tethered complex of the type MoO2Cl2(N–N), but instead indicated the formation of unidentate-bridged entities of the type [O2Mo–X–MoO2] with a metal–metal separation of 3.28 A. The molybdenum-containing MCM was active as a catalyst for the epoxidation of cyclooctene by tert-butyl hydroperoxide. However, this activity is due, at least in part, to leached molybdenum species in solution.

Immobilisation of rhodium acetonitrile complexes in ordered mesoporous silica

Rhodium acetonitrile complexes have been immobilised in the mesoporous silica MCM-41 by pore volume impregnation of a solution of the compound [Rh2(CH3CN)10](BF4)4 in acetonitrile. Powder XRD and N2 adsorption–desorption analysis of the derivatised material confirmed that the textural properties of the hexagonally ordered host were preserved during the grafting experiment and that the channels remained accessible. The BET specific surface area decreased from 1047 to 820 m2 g−1, while the specific total pore volume decreased from 0.85 to 0.64 cm3 g−1. The functionalised material was also characterised by MAS NMR (11B, 13C and 29Si), FTIR and Raman spectroscopy, Rh K-edge EXAFS spectroscopy, UV–Vis and luminescence spectroscopy. These studies revealed the existence of surface-attached dimeric species, with a rhodium–rhodium interatomic distance (2.58 A) similar to that in the compound [Rh2(CH3CN)10](BF4)4 (2.61 A). Exposure of this material to light promotes irreversible photodissociation of the dimeric species to give immobilised monomeric species.

Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry

Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems.

Bimetallic transition metal–ruthenium(II) complexes containing bridging bipyrimidine ligands

Abstract The ruthenium(II) complex [Ru([14]aneS4)(bpym)](BF4)2 ([14]aneS4=1,4,8,11-tetrathiacyclotetradecane, bpym=2,2′-bipyrimidine) has been prepared by substitution of the labile acetonitrile ligands in the complex [Ru([14]aneS4)(CH3CN)2](BF4)2 by bpym. Both the precursor acetonitrile complex and the polypyridyl complex were characterised by Ru K-edge EXAFS spectroscopy. In addition, the crystal structures of [Ru([14]aneS4)(bpym)](X)2 (X=BF4, PF6) were determined by X-ray diffraction. The bpym-bridged bimetallic complexes [{Ru([14]aneS4)}2(bpym)](BF4)4 and [{([14]aneS4)Ru}(bpym){ReO3Me}](BF4)2 were prepared using the ruthenium(II) monomeric bpym complex as starting material. In the case of the complex containing methyltrioxorhenium(VII) coordination of both metal centres to the bidentate bridging ligand was supported by a combination of Ru K-edge and Re L-edge XAFS spectroscopy, in addition to 1H NMR.

Modelling the luminescence of extended solids: an example of a highly luminescent MCM-41 impregnated with a Eu3+ β-diketonate complex

A regular MCM-41 type mesostructured silica was used as a support for the incorporation of the highly luminescent tris(β-diketonate) complex Eu(tta)3ephen yielding the hybrid MCM–Eu material. Suitable characterization by powder X-ray diffraction (XRD), thermogravimetric analyses (TGA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), 13C and 21Si solid state NMR spectroscopy and photoluminescence was accomplished. The combination of ultraviolet-visible spectroscopy (UV-Vis) and photoluminescence techniques shows that the complex incorporation seems to modify essentially the second Eu3+ coordination shell. For a material that has a simply impregnated lanthanide complex, the herein reported maximum 5D0 quantum yield value of 0.31 is a significantly high value, being almost in the same scale of the values obtained for the materials with covalently bonded complexes. A detailed theoretical photoluminescence study of the MCM–Eu with the recently developed Luminescence Package – LUMPAC is presented. The high accuracy of the theoretical calculations is achieved through the comparison with the experimental values. Aiming at a deeper understanding of the photoluminescence process, the ligand-to-Eu3+ intramolecular energy transfer and back-transfer rates were also predicted. The dominant pathway involves the energy transfer between the lowest energy ligand triplet and the 5D0 level (9.70 × 107 s−1).

Prevalence of overweight and obesity in portuguese adolescents: Comparison of different anthropometric methods

Background: The recommended anthropometric methods to assess the weight status include body mass index (BMI), skinfold thickness, and waist circumference. However, these methods have advantages and disadvantages regarding the classification of overweight and obesity in adolescents. Aims: The study was to analyze the correlation between the measurements of BMI, skinfold thickness and waist circumference to assess overweight and obesity in Portuguese adolescents. Materials and Methods: A sample of 966 students of Portugal was used. Of them, 437 (45.2%) were males and 529 (54.8%) were females aged between 10 and 16 years. The evaluations included BMI calculation, skinfold thickness, and waist circumference measurements. Results: This study revealed a high prevalence of overweight and obesity with values ranging from 31.6%, 61.4%, and 41.1% according to the measurement of BMI, skinfold thickness, and waist circumference, respectively. The results found a high level of correlation between BMI and skinfold thickness (P < 0.001, r = 0.712), between BMI and waist circumference (P < 0.001, r = 0.884), and waist circumference and skinfold thickness (P < 0.001, r = 0.701). Conclusions: This study revealed a high prevalence of overweight and obesity in Portuguese adolescents using three different anthropometric methods, where the BMI showed the lowest values of prevalence of overweight and obesity and the skinfold thickness showed the highest values. The three anthropometric methods were highly correlated.

Ureterocele: Antenatal Diagnosis and Management

Ureteroceles are cystic dilations of the intravesical submucosal ureter. Most cases are associated with complete ureteral and renal duplication, and association with ureterohydronephrosis is frequent. The authors describe the 4 cases of fetal ureterocele diagnosed from March 2008 to March 2012. Mean gestational age at diagnosis was 23 weeks (16-34 weeks). One of 4 cases progressed to severe hydronephrosis with megacystis and was referred to a Fetal Medicine Center for fetoscopy and laser ureterocelotomy. The remaining 3 cases did not need fetal therapy. Mean gestational age at delivery was 37 weeks. One case abandoned follow-up; 2 children were submitted to cystoscopic ureterocele incision and the child submitted to fetal therapy needed heminephrectomy due to recurrent urinary tract infections. In those 3 cases renal function was preserved. When a fetal ureterocele is diagnosed, close sonographic surveillance should be offered to monitor the possible urinary tract obstruction and assess the need for prenatal intervention. Fetal diagnosis is important to program the timing of delivery and postnatal care.

Synthesis and characterisation of ruthenium(II) complexes containing ferrocenyl-derived ligands

Ruthenium(II) complexes containing the macrocycle [14]aneS4 and pyridyl ligands with an end-capping ferrocene were prepared using [Ru([14]aneS4)(DMSO)Cl]Cl as the starting material. Substitution of the DMSO ligand by 4-ferrocenylpyridine (4-FP), ferrocenyl-4-pyridylacetylene (FPA) and pyridine (py) gave the complexes [Ru([14]aneS4)(L)Cl]Cl (L=4-FP, FPA, py). The acetonitrile complex [Ru([14]aneS4)(NCMe)2](BF4)2 was also prepared starting from [Ru([14]aneS4)(DMSO)Cl]Cl. UV/Vis absorption spectroscopy and cyclic voltammetry indicate low electronic communication between the metal centres in the heterobimetallic complexes. The crystal structure of [Ru([14]aneS4)(4-FP)Cl]Cl was determined by X-ray diffraction. Crystal data: C25.780H37.134Cl2FeNO1.288S4Ru, M=737.82, monoclinic, space group P2/n, a=13.192(1), b=7.6662(6), c=28.549(2) A, β=100.341(2)°, V=2840.4(4) A3, Z=4.

Marine sponge melanin: a new source of an old biopolymer

Various types of melanin have already been found in the majority of organisms, being this biopolymer considered as one of the major pigments present in nature. The presence of this pigment in marine sponges (Phylum Porifera, one of the simplest multicellular organisms) was postulated, but never characterized. In this context this work aims the extraction and characterization of a dark pigment observed in four different marine sponges species (Erylus mamillaris, Erylus discophorus var. deficiens, Pachymatisma johnstonia, Dercitus bucklandi). Characterization of the extracted biopolymer was performed using solid state analytical techniques, due to the characteristic non-solubility of melanin. Therefore, characterization techniques like SEM–EDS, IR, UV–vis, MALDI-MS, elemental analysis and X-ray powder diffraction (XRD) were used to identify the biopolymer. The results showed that the extracted material was obtained with high purity, being identified as melanin. The results also emphasize a large structure variability present in this pigment, showing different structure arrangements and composition depending on its source, which influences the UV behaviour. The structural characterization of this class of pigments is fundamental, allowing a better understanding of melanin properties.

The effectiveness of fingolimod in a Portuguese real-world population

INTRODUCTION Fingolimod is an oral treatment for Relapsing-Remitting Multiple Sclerosis (RRMS) with established efficacy in clinical trials. Post-marketing studies are important to assess its effectiveness in real-world populations. OBJECTIVES To report the effectiveness and safety of fingolimod in a real-world population. METHODS A retrospective study of patients with RRMS treated with fingolimod for at least six months. The demographic characteristics, Annualized Relapse Rate (ARR), Expanded Disability Status Score (EDSS), previous treatments and Adverse Events (AE) were analysed. RESULTS 104 patients were included, with a mean treatment duration of 21.06 months. First-line disease modifying therapy failure patients (n=56) had an ARR decrease of 68.53% (1.43 vs. 0.45, p<0.001), 66.07% of them were relapse-free, EDSS significantly decreased (2.5 vs. 2.0, p<0.001) and 91.07% showed no disability progression. In patients previously treated with natalizumab as a second-line drug mainly switched due to safety concerns (n=41), although the differences were not statistically significant, both the ARR and EDSS increased in 41.46% and 19.51% of patients, respectively. In treatment-naive patients (n=7) the ARR decreased 94.90% (1.57 vs. 0.08, p=0.027) and there was no disability progression. 56.7% of all patients experienced AE not considered serious in any of the cases. CONCLUSION In this population, fingolimod was an effective treatment after first-line treatment failure, decreasing both the ARR and EDSS, and may be an effective option after natalizumab.