排序方式: 共有29条查询结果,搜索用时 15 毫秒
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Jessica E. Waters Georg Berger Dr. Andrew J. Peel Dr. Raúl García-Rodríguez Dr. Andrew D. Bond Prof. Dominic S. Wright 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(47):12036-12040
Supramolecular main group chemistry is a developing field which parallels the conventional domain of metallo-organic chemistry. Little explored building blocks in this area are main group metal-based ligands which have the appropriate donor symmetry to build desired molecular or extended arrangements. Tris(pyridyl) main group ligands (E(py)3, E=main group metal) are potentially highly versatile building blocks since shifting the N-donor arms from the 2- to the 3-positions and 4-positions provides a very simple way of changing the ligand character from mononuclear/chelating to multidentate/metal-bridging. Here, the coordination behaviour of the first main group metal tris(4-pyridyl) ligands, E(4-py)3 (E=Sb, Bi, Ph−Sn) is explored, as well as their ability to build metal-organic frameworks (MOFs). The complicated topology of these MOFs shows a marked influence on the counter anion and on the ability of the E(4-py)3 ligands to switch coordination mode, depending on the steric and donor character of the bridgehead. This structure-directing influence of the bridgehead provides a potential building strategy for future molecular and MOF design in this area. 相似文献
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D. García-Rodríguez A. M. Carro R. Cela R. A. Lorenzo 《Analytical and bioanalytical chemistry》2010,398(2):1005-1016
A microwave-assisted extraction method followed by clean-up with solid-phase extraction (SPE) combined with large-volume injection
gas chromatography–tandem mass spectrometry (LVI-GC-MS/MS) for the analysis of 17 pesticides in wild and aquaculture edible
seaweeds has been developed. An experimental central composite design was employed to evaluate the effects of the main variables
potentially affecting the extraction (temperature, time, and solvent volume) and to optimize the process. The most effective
microwave extraction conditions were achieved at 125 °C and 12 min with 24 mL of hexane/ethyl acetate (80:20). SPE clean-up
of the extracts with graphitized carbon and Florisil, optimized by means of the experimental design, proved to be efficient
in the removal of matrix interferences. The analytical recoveries were close to 100% for all the analytes, with relative standard
deviations lower than 13%. The limits of detection ranged from 0.3 to 23.1 pg g−1 and the limits of quantification were between 2.3 and 76.9 pg g−1, far below the maximum residue levels established by the European Union for pesticides in seaweed. The results obtained prove
the suitability of the microwave-assisted extraction for the routine analysis of pesticides in aquaculture and wild seaweed
samples. 相似文献
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Bórquez J Molina-Salinas GM Loyola LA San-Martín A Peña-Rodríguez LM Said-Fernández S 《Natural product research》2011,25(6):653-657
A new azorellane diterpenoid has been isolated and identified from the aerial parts of Azorella madreporica Clos. The structure of 1 was established by one- and two-dimensional NMR techniques. 相似文献
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Macrocycle formation by proton-template-induced dimerization of complexes with (alkoxoimino)pyridine
Álvarez CM García-Rodríguez R Martín-Alvarez JM Miguel D Turiel JA 《Inorganic chemistry》2012,51(7):3938-3940
The existence of a strong hydrogen bond between two molecules of an (alkoxoimino)pyridinemanganese(I) complex induces their dimerization and the formation of a metallamacrocycle. The expected intramolecular attack of the alkoxo moiety is disfavored. 相似文献
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Barluenga J García-Rodríguez J Martínez S Suárez-Sobrino AL Tomás M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(12):3201-3210
We examined the reactivity of dimethylaminodiazafulvene 1 toward Fischer alkenylcarbene 2 and alkynylcarbene 3 complexes. Diazafulvene 1 reacts with alkenylcarbenes 2 through a formal [6+3] heterocyclization in a regio- and stereoselective manner to afford dihydroimidazo[1,2-a]pyridines 4. Acid-promoted dimethylamine elimination in compound 4 c gives rise to the aromatic imidazo pyridine 5. A likely mechanism for this reaction is a 1,2-nucleophilic addition/[1,2]-shift metal-promoted cyclization sequence. On the other hand, diazafulvene 1 and alkynyl carbenes 3 undergo a [6+2] cyclization to afford pyrrolo[1,2-a]imidazole carbene complex 6 that can be readily oxidized to the corresponding esters 7. When enynylcarbenes 3 e-i are treated with diazafulvene 1, consecutive and diastereoselective [6+2]/cyclopentannulation cyclization reactions take place affording new polycyclic complex systems 8, 9, and 12 that can be appropriately demetallated to the corresponding imidazole-based polyfused systems 10, 11, and 13 respectively. Finally, enynylcarbenes 3 d,f undergo consecutive [6+2]/[5+1] cyclization reactions with diazafulvene 1 and tBuNC, respectively, to yield tetracyclic adducts 14 and 15. All these processes result in high yields and provide a route to the preparation of imidazopyridines and pyrroloimidazoles as well as other polycyclic molecules that contain imidazole groups, which are interesting from a pharmacological and biological point of view. 相似文献
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Navarrete-Guijosa A Navarrete-Casas R Valenzuela-Calahorro C López-González JD García-Rodríguez A 《Journal of colloid and interface science》2003,264(1):60-66
In this paper we used a previously reported model for examining the adsorption of nonelectrolytes in solution by solid adsorbents to study the adsorption of lithium(I) cations by acid and sodium amberlites, which is an ion-exchange process. Based on the results, both are equilibrium processes and obey a kinetic law with a unity partial order in the Li+ concentration. The kinetic results were used to calculate the specific rate constants and thermodynamic activation functions involved. Also, equilibrium isotherms were used to determine the corresponding ion-exchange capacities, the individual equilibrium constants, and the thermodynamic functions for the overall process. 相似文献