José A. Fernandes

Thermal Transformation of a Layered Multifunctional Network into a Metal–Organic Framework Based on a Polymeric Organic Linker

The preparation of layered [La(H(3)nmp)] as microcrystalline powders from optimized microwave-assisted synthesis or dynamic hydrothermal synthesis (i.e., with constant rotation of the autoclaves) from the reaction of nitrilotris(methylenephosphonic acid) (H(6)nmp) with LaCl(3)·7H(2)O is reported. Thermogravimetry in conjunction with thermodiffractometry showed that the material undergoes a microcrystal-to-microcrystal phase transformation above 300 °C, being transformed into either a three-dimensional or a two-dimensional network (two models are proposed based on dislocation of molecular units) formulated as [La(L)] (where L(3-) = [-(PO(3)CH(2))(2)(NH)(CH(2)PO(2))O(1/2)-](n)(3n-)). The two crystal structures were solved from ab initio methods based on powder X-ray diffraction data in conjunction with structural information derived from (13)C and (31)P solid-state NMR, electron microscopy (SEM and EDS mapping), FT-IR spectroscopy, thermodiffractometry, and photoluminescence studies. It is shown that upon heating the coordinated H(3)nmp(3-) anionic organic ligand undergoes a polymerization (condensation) reaction to form in situ a novel and unprecedented one-dimensional polymeric organic ligand. The lanthanum oxide layers act, thus, simultaneously as insulating and templating two-dimensional scaffolds. A rationalization of the various steps involved in these transformations is provided for the two models. Photoluminescent materials, isotypical with both the as-prepared ([(La(0.95)Eu(0.05))(H(3)nmp)] and [(La(0.95)Tb(0.05))(H(3)nmp)]) and the calcined ([(La(0.95)Eu(0.05))(L)]) compounds and containing stoichiometric amounts of optically active lanthanide centers, have been prepared and their photoluminescent properties studied in detail. The lifetimes of Eu(3+) vary between 2.04 ± 0.01 and 2.31 ± 0.01 ms (considering both ambient and low-temperature studies). [La(H(3)nmp)] is shown to be an effective heterogeneous catalyst in the ring opening of styrene oxide with methanol or ethanol, producing 2-methoxy-2-phenylethanol or 2-ethoxy-2-phenylethanol, respectively, in quantitative yields in the temperature range 40-70 °C. The material exhibits excellent regioselectivity to the β-alkoxy alcohol products even in the presence of water. Catalyst recycling and leaching tests performed for [La(H(3)nmp)] confirm the heterogeneous nature of the catalytic reaction. Catalytic activity may be attributed to structural defect sites. This assumption is somewhat supported by the much higher catalytic activity of [La(L)] in comparison to [La(H(3)nmp)].

Lanthanide-polyphosphonate coordination polymers combining catalytic and photoluminescence properties.

A rapid, mild and high-yield microwave synthesis of 1D isotypical [Ln(H4bmt)(H5bmt)(H2O)2]·3H2O coordination polymers is presented. The La(3+)-based material is highly active as a heterogeneous catalyst in the methanolysis of styrene oxide at nearly room temperature. Eu(3+)- and Tb(3+)-doped materials are very effective UV-to-visible light converters.

Multifunctional micro- and nanosized metal–organic frameworks assembled from bisphosphonates and lanthanides

Phase-pure and highly crystalline [Ln(Hpmd)(H2O)] materials [where Ln3+ = Eu3+ (1), Gd3+ (2) and Tb3+ (3); H4pmd = 1,4-phenylenebis(methylene)diphosphonic acid] were prepared by using three distinct approaches: (i) conventional hydrothermal synthesis (180 °C, 3 days); (ii) microwave-assisted heating (50 W irradiation power, 40 °C, 5 seconds; nano-sized aggregates with sizes ranging between 100 and 150 nm); and (iii) ultrasound-assisted synthesis which, for highly diluted reactive mixtures (Ln3+ : H4pmd : H2O of 1 : 1 : 7200), permitted the preparation of isolated nano-crystals at ambient temperature with 5 minutes of ultrasonic irradiation. Compounds were structurally characterized by powder X-ray diffraction (Rietveld refinement and variable-temperature studies), thermogravimetry, vibrational spectroscopy, elemental analysis and electron microscopy (SEM and EDS). The magnetic behavior of 1 and 2 was investigated between ambient temperature and ca. 2 K revealing that the Ln3+ cations act as isolated centers. A strategy to calculate the vibrational spectra of MOF structures and based on the known embedded-clusters approach is proposed and applied to [Ln(Hpmd)(H2O)]. This allowed the identification, along with deuteration of the materials, of the vibrational modes of the confined water molecule in the structure. Compound 1 was tested in the methanolysis of styrene oxide at 55 °C: it is shown that microcrystalline 1 (1-m) does not possess significant catalytic activity; on the other hand, the nano-sized counterpart (1-n) exhibits relatively high catalytic activity and excellent selectivity to 2-methoxy-2-phenylethanol (100% yield within 48 h of reaction time). Photoluminescence studies both at ambient and low temperatures showed, on the one hand, that bulk materials are composed of a single lanthanide site and, on the other hand, that the organic linker is a suitable sensitizer of Tb3+ (absolute quantum yield of ca. 14% for 3). It is further demonstrated that the coordinated water molecule has a pivotal role in the quenching of the photoluminescence of Eu3+ in 1: deuteration of the material results in a ca. 3.4 times improvement of the decay time (e.g., at 300 K the lifetime improves from 0.58 ± 0.01 ms to 1.98 ± 0.01 ms).

Chloramphenicol·cyclodextrin inclusion compounds: co-dissolution and mechanochemical preparations and antibacterial action

β-Cyclodextrin (βCD) inclusion compounds of chloramphenicol in the solid-state were prepared via two different procedures, co-crystallisation from aqueous solution and the solvent-free method of co-grinding. Chloramphenicol inclusion into permethylated βCD (TRIMEB) was also performed by co-dissolution in ethanol. The co-crystallisation procedure was the best for preparing chloramphenicol·βCD in 1:1 stoichiometry in high purity, while with the co-grinding treatment and the same starting proportion, a complete inclusion was not achieved. Microcrystals of chloramphenicol·βCD inclusion compound presented polymorphism, crystallising simultaneously in the triclinic P1 or monoclinic C2 space groups. Only crystals of the latter were suitable for single-crystal diffraction and data for the guest atoms was comprised of a smeared-out electron cloud, so theoretical calculations were used to propose their plausible geometry and location inside the host molecules. The co-grinding procedure curbed polymorphism and allowed the preparation of chloramphenicol·βCD in the amorphous state; chloramphenicol·TRIMEB prepared by co-dissolution of the components in a 1:1 proportion was also an amorphous material. The influence of inclusion with βCD and TRIMEB on the antimicrobial performance of chloramphenicol was evaluated, and both inclusion compounds demonstrated selective action against Enterococcus faecalis strains ATCC 29212 and A33562 and Listeria monocytogenes ATCC 7644. Chloramphenicol·TRIMEB also had higher activity against the E. faecalis strains A35906, 9308 and E4856 and against Listeria inocua.

Luminescence properties of composites made of a europium(III) complex and electroluminescent polymers with different energy gaps

We present the optoelectronic properties of composites made of a europium(III) complex, Eu(NTA)3 phen (where NTA=1-(2-naphthoyl)-3,3,3-trifluoroacetonate; phen=1,10-phenantroline), dispersed in three electroluminescent polymers, namely, poly(N-vinylcarbazole), poly(9,9-dioctylfluorene) and poly(9,9-dioctylfluorene-alt-benzothiadiazole). We find that the photo- and electroluminescence (EL) properties of these composites are well rationalized in terms of the relative position of the frontier levels of the host polymers and of the europium complex. We find also that charge recombination at the europium complex sites plays a key role on the EL properties of the composites.

Photoluminescent layered lanthanide–organic framework based on a novel trifluorotriphosphonate organic linker

A series of fluorinated lanthanide–organic frameworks (LnOFs), formulated as [Ln(H3tftp)(H2O)] [where Ln3+ = La3+ (1), (La0.95Eu0.05)3+ (2), (La0.95Tb0.05)3+ (3) and (La0.94Eu0.03Tb0.03)3+ (4)], has been successfully prepared, under hydrothermal conditions, using the novel ((2,4,6-trifluorobenzene-1,3,5-triyl)tris(methylene))triphosphonic acid (H6tftp) organic ligand and Ln3+ cations as metallic centers. The three-step preparation of the tripodal H6tftp ligand is described. H6tftp and all intermediate molecules involved in the synthesis were fully characterized in the liquid and solid states. While the La3+-based LnOF material was isolated as single-crystals, with its crystal structure being fully described by single-crystal X-ray diffraction, phase identification of the Eu3+- and Tb3+-based materials was performed by powder X-ray diffraction. It is shown that the crystal structure of this isotypical series of materials is based on a neutral two-dimensional ∞2[Ln(H3tftp)(H2O)] coordination polymer placed in the ac plane of the unit cell, exhibiting a uninodal 4-connected square layered topology. It is shown that the most striking and supramolecular relevant interactions are classical O–H⋯O hydrogen bonds within the polymer, further contributing to the structural robustness of the layer. Prepared LnOFs were fully characterized in the solid state using elemental and thermogravimetric analysis, electron microscopy (SEM and EDS) and FT-IR spectroscopy. Compound 1 was further studied using solid-state NMR (31P HPDEC MAS and 13C{1H} CP MAS) and thermodiffractometry. Photoluminescent studies have been performed on the mixed-lanthanide materials 2 and 3.

Droid Jacket: Using an Android based smartphone for team monitoring

Professionals such as First Responders are frequently exposed to extreme environmental conditions, which induce stress and fatigue during extensive periods of time. In this scenario, the main issues are the quantification and evaluation of stress and fatigue, since uncontrolled levels have a profound and negative impact on human health and performance. Based on an existing wearable monitoring solution - the Vital Jacket®- we propose an individual and team monitoring mobile solution called DroidJacket. DroidJacket is based on Android mobile devices and provides data aggregation, processing, visualization and optionally relaying services. The DroidJacket design is plugin oriented, integrating analysis modules, namely an online ECG plugin for both real time pulse and arrhythmia detection.

Metal-organic frameworks based on uranyl and phosphonate ligands

Three new crystalline metal-organic frameworks have been prepared from the reaction of uranyl nitrate with nitrilotris(methylphosphonic acid) [H6nmp, N(CH2PO3H2)3], 1,4-phenylenebis(methylene)diphosphonic acid [H4pmd, C6H4(PO3H2)2], and (benzene-1,3,5-triyltris(methylene))triphosphonic acid [H6bmt, C6H3(PO3H2)3]. Compound [(UO2)2F(H3nmp)(H2O)]·4H2O (I) crystallizes in space group C2/c, showing two crystallographically independent uranyl centres with pentagonal bipyramidal coordination geometries. While one metal centre is composed of a {(UO2)O3(μ-F)}2 dimer, the other comprises an isolated {(UO2)O5} polyhedron. Compound [(UO2)(H2pmd)] (II) crystallizes in space group P21/c, showing a centrosymmetric uranyl centre with an octahedral {(UO2)O4} coordination geometry. Compound [(UO2)3(H3bmt)2(H2O)2]·14H2O (III) crystallizes in space group P\bar 1, showing two crystallographically independent uranyl centres. One uranyl centre is a {(UO2)O5} pentagonal bipyramid similar to that in (I), while the other is a {(UO2)O4} centrosymmetric octahedron similar to that in (II). Compounds (I) and (III) contain solvent-accessible volumes accounting for ca 23.6 and 26.9% of their unit-cell volume, respectively. In (I) the cavity has a columnar shape and is occupied by disordered water molecules, while in (III) the cavity is a two-dimensional layer with more ordered water molecules. All compounds have been studied in the solid state using FT-IR spectroscopy. Topological studies show that compounds (I) and (III) are trinodal, with 3,6,6- and 4,4,6-connected networks, respectively. Compound (II) is instead a 4-connected uninodal network of the type cds.

Analysis of the microcrystalline inclusion compounds of triclosan with β-cyclodextrin and its tris-O-methylated derivative.

Solid 1:1 inclusion compounds of triclosan with native and permethylated β-cyclodextrin (β-CD and TRIMEB) were prepared by co-crystallisation and co-evaporation, respectively, and studied by FT-IR and (13)C{(1)H} CP/MAS NMR spectroscopies, thermogravimetric analysis, X-ray diffraction and theoretical calculations. Results showed that triclosan inclusion into TRIMEB afforded an amorphous solid, whilst β-CD·triclosan is composed of microcrystals belonging to two different phases. In the phase featuring larger crystals, X-ray diffraction was carried out and the β-CD host units, packing head-to-head in infinite channels, were refined; the geometry for the included but highly disordered triclosan molecules was assessed by theoretical calculations. The bacterial growth inhibitory action of the inclusion compounds was studied in comparison to that of pure triclosan on Gram-negative (Salmonella, Escherichia) and Gram-positive strains (Bacillus, Listeria, Enterococcus and Staphylococcus) typically associated with human pathologies, and also on environmental bacteria isolated from different soil and water sources. The antimicrobial activities obtained in the present work showed that, of the two CD hosts, TRIMEB brings the most favourable carrier effect: it reduced the toxicity of triclosan against some of the environmental strains and afforded slightly higher action against virulent strains.

Syntheses and dynamic NMR studies on 3-(1′-indenyl)propyl-N,N-bis(trimethylsylil)amine metal derivatives

Abstract The syntheses and characterisation of C 9 H 6 (X)(CH 2 ) 3 N(SiMe 3 ) 2 (X=H ( 2 ), SiMe 3 ( 4 ), Li ( 3 )) are described. The reactions of 4 with TiCl 4 , [TiCp*Cl 3 ] and NbCl 5 led to the isolation of [Ti{N(H)(CH 2 ) 3 C 9 H 6 SiMe 3 }Cl 3 ] ( 5 ), [TiCp*{N(H)(CH 2 ) 3 (C 9 H 6 SiMe 3 )}Cl 2 ] ( 8 ) and [Nb{N(CH 2 ) 3 (C 9 H 6 SiMe 3 )}Cl 3 ] 2 ·THF ( 9 ), respectively. The reaction of 3 with TiCl 4 led to the ansa -bridged indenyl-amido complex [Ti{η 5 :σ,π(C 9 H 6 )(CH 2 ) 3 N(SiMe 3 )}Cl 2 ] ( 7 ) and with [Mo(CO) 2 (CH 3 CH 2 CN) 2 (C 3 H 5 )Cl] gave [{η 5 -C 9 H 6 (CH 2 ) 3 N(SiMe 3 ) 2 }Mo(CO) 2 (C 3 H 5 )] ( 10 ). Two conformers, corresponding to the limit orientations of the allyl ligand ( endo and exo ) have been identified in solution, by NMR. The activation parameters for the slow endo / exo isomerisation process were determined.