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A series of lead(II) complexes incorporating benzoate derivative ligands was prepared: [Pb(2MeOBz)2]n (1), [Pb(2MeOBz)2(H2O)]n (2), [Pb2(1,4Bzdiox)4(DMSO)]n (3), [Pb(1,4Bzdiox)2(H2O)]n (4), [Pb(Pip)2(H2O)]n (5), and [Pb(Ac)(Pip)2(MeOH)]n (6) (2MeOBz: 2-methoxybenzoate; 1,4Bzdiox: 1,4-benzodioxan-5-carboxylate; DMSO: dimethylsulfoxide; Ac: acetate; Pip: piperonylate; MeOH: methanol). All compounds were characterized via elemental analysis, ATR-FTIR spectroscopy, and powder XRD. In addition, the crystal structures of some compounds were elucidated. Compounds 1 and 2, involving 2-methoxybenzoate, were closely related, only differing in the presence of one extra aqua ligand found for the latter. However, this implies key changes in the studied properties, e.g., 2 shows solid-state luminescence that displays a different color as a function of the crystal orientation, while 1 does not. The crystal structure of 2 revealed a 1D coordination polymer. A similar relationship was found between compounds 3 and 4, incorporating 1,4-benzodioxan-5-carboxylate. In this pair, only 4, with aqua ligands, displayed a greenish-yellow-color solid-state luminescence. Furthermore, two new lead(II) piperonylate complexes, 5 and 6, were obtained from the reaction between lead(II) acetate and piperonylic acid. In water, all acetate ligands in the metal precursor were displaced and [Pb(Pip)2(H2O)]n (5) was isolated, while in methanol, a mixed acetate–piperonylate complex, [Pb(Ac)(Pip)2(MeOH)]n (6), was precipitated. Considering only conventional Pb-O bonds, the crystal structure of 6 was described as a 1D coordination polymer, although, additionally, the chains were associated via tetrel bonds, defining an extended 2D architecture.

The development of effective array biosensorsrelies heavily on careful control of the density of surface-immobilized ligands on the transducing platform. In this paperwe describe the synthesis of new dextran−lipase conjugates foruse in immobilizing low molecular weight haptens onto glassplanar waveguides for immunosensor development. Theconjugates were synthesized by immobilizing bacterial thermoalkalophilic lipases (Geobacillus thermocatenulatuslipase 2,BTL2) on agarose macroporous beads, followed by covalent coupling to dextran networks of variable molecular weight (1500−40000). The chimeras were immobilized via nonspecific hydrophobic interactions onto glass planar waveguides modified with1,1,1,3,3,3-hexamethyldisilazane to obtain highly ordered and homogeneous molecular architectures as confirmed by atomic forcemicroscopy. Microcystin LR (MCLR) was covalently bound to the dextran−BTL2 conjugates. The usefulness of this approach inimmunosensor development was demonstrated by determining amounts of MCLR down to a few picograms per liter with anautomated array biosensor and evanescent wave excitation forfluorescence measurements of attached DyLight649-labeledsecondary antibody. Modifying BTL2 with dextrans of an increased molecular weight (>6000) provided surfaces with anincreased loading capacity that was ascribed to the production of three-dimensional surfaces by the effect of analyte binding deepin the volume, leading to expanded dynamic ranges (0.09−136.56 ng L−1), lower limits of detection (0.007±0.001 ng L−1), andlower IC50values (4.4±0.7 ng L−1). These results confirm the effectiveness of our approach for the development of high-performance biosensing platforms., Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

The development of nanostructured composites made of metal-organic frameworks (MOFs) and graphene-based components, including exfoliated nanoplates of graphene oxide (GO) or reduced (rGO) graphene oxide, is an area of great interest in gas storage and separation. To improve the industrial viability, it is commonly demanded to build these nanocomposites with the shape of compact units, such as monoliths, foams, pellets, or films. Methods to generate those 3D nanocomposites involving rGO are abundant; however, they become scarce when GO is the desired support due to the difficulty in maintaining the carbon matrix oxidized during the structuration process. In this work, a methodology based on the use of supercritical CO2 (scCO2) is described for the synthesis of nanocomposites involving a discontinuous MOF phase, e.g. nanoparticles (NPs) of HKUST-1, decorating the surface of a continuous GO matrix, with surface oxygen groups favoring MOF attachment. The use of this new supercritical methodology allows the nanostructuration of the composite in the form of 3D aerogels while avoiding the reduction of GO. Enhanced values of textural properties, determined by low-temperature N2 adsorption-desorption, were observed for the nanocomposites in comparison to the values calculated for similar physical mixtures, highlighting an increase of 40-45% in the value of the surface area for samples with a high percentage of HKUST-1. Moreover, the composite aerogels, displaying a type II isotherm, outperform pristine HKUST-1 in regard to the CH4 practical working capacity at high pressure. Particularly, a composite exhibiting more than 2-fold the working capacity of net HKUST-1 NPs was obtained. Columns involving the composite aerogel as the stationary phase were used to study the separation of N2/CO2 and CH4/CO2 gas mixtures. The results showed a high selectivity of the nanostructured HKUST-1@GO composites for CO2, with breakthrough times of ca. 20 min g-1 and stable cyclic operations.