One-pot preparation of surface modified boehmite nanoparticles with rare-earth cyclen complexes

We report on the one-pot synthetic procedure of cyclen derivatives bearing three acetate groups attached on boehmite nanoparticles, the complexing capabilities of these inorganic-organic hybrid materials with rare earth cations, and the behaviour as contrast agents or fluorescence probes.     

Cu2+ and AMP complexation of enlarged tripodal polyamines

The synthesis, characterization, Cu2+ coordination and interaction with AMP of three tripodal polyamines are reported. The polyamines are based on the structure of the tetraamine (tren) which has been enlarged with three propylamino functionalities (), with a further anthrylmethyl fragment at one of its terminal primary nitrogens () or with naphthylmethyl fragments at its three ends (). The protonation constants of all three polyamines show that at pH 6, all six primary and secondary nitrogen atoms in the arms are protonated. The interaction with Cu2+ and AMP (adenosine-5'-monophosphate) has been studied by potentiometric, UV-Vis, ESI-MS spectroscopy and NMR techniques. pH-Metric, NMR and ESI/MS techniques indicate that and form with AMP adducts of 1:1, 2:1 and 3:1 AMP:L stoichiometries in water. This is one of the first examples for the formation of such complexes in aqueous solution. Formation of ternary complexes between , , , Cu2+ and AMP is observed. Paramagnetic NMR techniques have been used to obtain structural information on the binding mode of AMP to the Cu2+- binuclear complexes.     

Sobre la necesidad de controlar el error de discretización de elementos finitos en optimización de forma estructural con algoritmos evolutivos

This work analyzes the influence of the discretization error contained in the Finite Element (FE) analyses of each design configuration proposed by the structural shape optimization algorithms over the behavior of the algorithm. The paper clearly shows that if FE analyses are not accurate enough, the final solution provided by the optimization algorithm will neither be optimal nor satisfy the constraints. The need for the use of adaptive FE analysis techniques in shape optimum design will be shown. The paper proposes the combination of two strategies to reduce the computational cost related to the use of mesh adaptivity in evolutionary optimization algorithms: (a) the use of the algorithm described by Bugeda et al. [1] which reduces the computational cost associated to the adaptive FE analysis of each geometrical configuration and, (b) the successive increase of the required accuracy of the FE analyses in order to obtain a considerable reduction of the computational cost in the early stages of the optimization process.     

Synthesis and H+, Cu2+, and Zn2+ coordination behavior of a bis(fluorophoric) bibrachial lariat aza-crown

The synthesis, protonation behavior, and Cu2+ and Zn2+ coordination chemistry of the novel bibrachial aza lariat ether (naphthalen-1-ylmethyl)[2-(20-[2-[(naphthalen-1-ylmethyl)amino]ethyl]-3,6,9,17,20,23,29,30-octaazatricyclo[23.3.1.1*11,15*]triaconta-1(29),11(30),12,14,25,27-hexaen-6-yl)ethyl]amine (L) are discussed. The macrocycle, which has two aminoethyl naphthyl moieties symmetrically appended to a 2:2 azapyridinophane structure, displays, in the pH range 2-11, six protonation steps that correspond to the protonation of the secondary amino groups. Steady-state fluorescence measurements show emissions due to the monomer and to the excimer formed between the two naphthalene fragments of the macrocycle. The time-resolved fluorescence data, obtained by the time-correlated single photon counting technique, show that a significant percentage of excimer is preformed as ground-state dimers. The ligand L forms with the metal ions Cu2+ and Zn2+ mono- and dinuclear complexes in aqueous solution. The influence of metal coordination in the fluorescence emission of L is analyzed. The acid-base, coordination capabilities, and emissive behavior of L are compared with those presented by its synthetic precursor L1, which has a tripodal tris(2-aminoethyl)amine structure functionalized at one of its terminal amino groups with a naphthyl moiety.