2,625 research outputs found

    Low temperature scattering with the R-matrix method: the Morse potential

    Get PDF
    Experiments are starting to probe collisions and chemical reactions between atoms and molecules at ultra-low temperatures. We have developed a new theoretical procedure for studying these collisions using the R-matrix method. Here this method is tested for the atom -- atom collisions described by a Morse potential. Analytic solutions for continuum states of the Morse potential are derived and compared with numerical results computed using an R-matrix method where the inner region wavefunctions are obtained using a standard nuclear motion algorithm. Results are given for eigenphases and scattering lengths. Excellent agreement is obtained in all cases. Progress in developing a general procedure for treating ultra-low energy reactive and non-reactive collisions is discussed.Comment: 18 pages, 6 figures, 3 tables, conferenc

    Heterometallic Titanium-Organic Frameworks as Dual Metal Catalysts for Synergistic Non-Buffered Hydrolysis of Nerve Agent Simulants

    Get PDF
    Heterometallic metal-organic frameworks (MOFs) can offer important advantages over their homometallic counterparts to enable targeted modification of their adsorption, structural response, electronic structure, or chemical reactivity. However, controlling metal distribution in these solids still remains a challenge. The family of mesoporous titanium-organic frameworks, MUV-101(M), displays heterometallic TiM2 nodes assembled from direct reaction of Ti(IV) and M(II) salts. We use the degradation of nerve agent simulants to demonstrate that only TiFe2 nodes are capable of catalytic degradation in non-buffered conditions. By using an integrative experimental-computational approach, we rationalize how the two metals influence each other, in this case, for a synergistic mechanism reminiscent of bimetallic enzymes. Our results highlight the importance of controlling metal distribution at an atomic level to span the interest of heterometallic MOFs to a broad scope of cascade or tandem reactions. Summary Mixed-metal or heterometallic metal-organic frameworks (MOFs) are gaining importance as a route to produce materials with increasing chemical and functional complexities. We report a family of heterometallic titanium frameworks, MUV-101(M), and use them to exemplify the advantages of controlling metal distribution across the framework in heterogeneous catalysis by exploring their activity toward the degradation of a nerve agent simulant of Sarin gas. MUV-101(Fe) is the only pristine MOF capable of catalytic degradation of diisopropyl-fluorophosphate (DIFP) in non-buffered aqueous media. This activity cannot be explained only by the association of two metals, but to their synergistic cooperation, to create a whole that is more efficient than the simple sum of its parts. Our simulations suggest a dual-metal mechanism reminiscent of bimetallic enzymes, where the combination of Ti(IV) Lewis acid and Fe(III)–OH Brönsted base sites leads to a lower energy barrier for more efficient degradation of DIFP in absence of a base.Financial support for this work was provided by the Marie Skłodowska-Curie Global Fellowships (749359-EnanSET, N.M.P) within the European Union research and innovation framework programme (2014-2020

    Selective and Efficient Mitochondrial Staining with Designed 2,1,3-Benzothiadiazole Derivatives as Live Cell Fluorescence Imaging Probes

    Get PDF
    Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Novel designed 2,1,3-benzothiadiazole fluorescent probes were synthesized, characterized and applied as live cell fluorescence imaging probe staining only mitochondria in mammalian cancer cell lines (MCF-7). The efficiency of these new probes was found to be much superior to that of the commercially available MitoTracker (R) Red. Cellular and in vitro experiments allowed better understanding of the relationship between the planned molecular architecture of the new dyes and the observed cellular selectivity.234770781Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundacao de Apoio a Pesquisa do Distrito Federal (FAPDF)INCT-CatalysisBrasilia Fundacao de Empreendimentos Cientificos e Tecnologicos (Finatec)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)PetrobrasDPP-UnBQuiCSI TeamLMC (IQ-UnB)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP
    corecore