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91.
Jorge Pasán Joaquín Sanchiz Laura Cañadillas-Delgado Oscar Fabelo Mariadel Déniz Francesc Lloret Miguel Julve Catalina Ruiz-Pérez 《Polyhedron》2009,28(9-10):1802-1807
Two new methylmalonate-bridged copper(II) complexes with the formulas [Cu(3-Ipy)(Memal)(H2O)] (1) and [Cu(2,4′-bpy)(Memal)(H2O)] · 3H2O (2) [Memal = methylmalonate dianion, 3-Ipy = 3-iodopyridine, 2,4′-bpy = 2,4′-bipyridine] have been synthesized and characterized by X-ray diffraction. Both compounds crystallize in the monoclinic space group P21/n and Z = 4, with unit cell parameters a = 8.5874(13) Å, b = 7.1738(14) Å, c = 19.093(5) Å, β = 99.509(15)° in 1 and a = 17.375(4) Å, b = 7.3305(14) Å, c = 14.247(3) Å, β = 111.409(15)° in 2. The structures of 1 and 2 consist of zigzag chains of anti-syn carboxylate-bridged copper(II) ions running along the b direction. The pyridine-like ligands occupy one equatorial position of the copper environment avoiding the formation of the sheet-like arrangement observed in previously reported Memal complexes. The chains are grouped together in hydrophilic layers through hydrogen bonds and the layers are pillared through the 3-Ipy (1) and 2,4′-bpy (2) ligands which are stacked through π–π interactions involving alternatively aromatic ligands from two adjacent chains. Magnetic susceptibility measurements of both compounds in the temperature range 2–290 K show the occurrence of intrachain ferromagnetic interactions between the copper(II) ions [J = +2.66(2) cm?1 (1) and J = +2.62(2) cm?1 (2)]. 相似文献
92.
García-Couceiro U Olea D Castillo O Luque A Román P de Pablo PJ Gómez-Herrero J Zamora F 《Inorganic chemistry》2005,44(23):8343-8348
The compound [Mn(mu-ox)(4atr)2]n (1) (ox = oxalato and 4atr = 4-amine-1,2,4-triazole) has been synthesized and characterized by FT-IR spectroscopy, thermal analysis, variable-temperature magnetic measurements, and X-ray single-crystal diffraction methods. The crystal structure of compound 1 consists of one-dimensional linear chains in which trans-[Mn(4atr)2]2+ units are sequentially bridged by centrosymmetric bis-bidentate oxalato ligands. Cryomagnetic measurements show an overall antiferromagnetic behavior of the compound. Isolated chains of this polymer have been obtained by sonication of 1 in ethanol or treatment of the polymer with NaOH and morphologically characterized on highly oriented pyrolitic graphite and mica surfaces by atomic force microscopy and scanning tunneling microscopy. The procedures employed to obtain single chains of this coordination polymer open a route for future nanotechnological applications of these types of materials. 相似文献
93.
N. Teodorescu und Catalina Demetrescu 《Fresenius' Journal of Analytical Chemistry》1967,232(2):119-120
Ohne Zusammenfassung 相似文献
94.
A new high polygalacturonase (PG)-producing Kluyveromyces marxianus strain was isolated from coffee wet-processing wastewater. PG production in this strain is not repressed in the presence
of 100g/L of glucose and, being growth-associated, reached its maximum accumulation in the culture medium at the beginning
of the stationary phase. Oxygen and galacturonic acid negatively regulated enzyme synthesis, and glucose as the carbon source
afforded better enzyme yields than lactose. The data reported here show that this strain exhibits the highest index of PG
production among the wild-type strains reported so far (18.8U/mL). PG was readily purified by ion-exchange chromatography
on SP-Sepharose FF. The activity corresponded to a single protein with an M
r of 41.7 kDa according to sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme was stable in the pH range
of 3.0–5.0 and displayed an optimal temperature of 55°C; it showed a typical endo-splitting way of substrate hydrolysis and exhibited a fair degree of activity on pectin with a high degree of esterification. 相似文献
95.
Kristian Piscicchia Johann Marton Sergio Bartalucci Massimiliano Bazzi Sergio Bertolucci Mario Bragadireanu Michael Cargnelli Alberto Clozza Raffaele Del Grande Luca De Paolis Carlo Fiorini Carlo Guaraldo Mihail Iliescu Matthias Laubenstein Marco Miliucci Edoardo Milotti Fabrizio Napolitano Andreas Pichler Alessandro Scordo Hexi Shi Diana Laura Sirghi Florin Sirghi Laura Sperandio Oton Vazquez Doce Johann Zmeskal Catalina Curceanu 《Entropy (Basel, Switzerland)》2020,22(11)
The VIP collaboration is performing high sensitivity tests of the Pauli Exclusion Principle for electrons in the extremely low cosmic background environment of the underground Gran Sasso National Laboratory INFN (Italy). In particular, the VIP-2 Open Systems experiment was conceived to put strong constraints on those Pauli Exclusion Principle violation models which respect the so-called Messiah–Greenberg superselection rule. The experimental technique consists of introducing a direct current in a copper conductor, and searching for the X-rays emission coming from a forbidden atomic transition from the L shell to the K shell of copper when the K shell is already occupied by two electrons. The analysis of the first three months of collected data (in 2018) is presented. The obtained result represents the best bound on the Pauli Exclusion Principle violation probability which fulfills the Messiah–Greenberg rule. 相似文献
96.
Ricardo Prato Torres Catalina Domínguez Stiven Díaz 《Numerical Methods for Partial Differential Equations》2019,35(1):325-348
In this article, we conduct an a posteriori error analysis of the two‐dimensional time‐dependent Stokes problem with homogeneous Dirichlet boundary conditions, which can be extended to mixed boundary conditions. We present a full time–space discretization using the discontinuous Galerkin method with polynomials of any degree in time and the ? 2 ? ?1 Taylor–Hood finite elements in space, and propose an a posteriori residual‐type error estimator. The upper bounds involve residuals, which are global in space and local in time, and an L 2‐error term evaluated on the left‐end point of time step. From the error estimate, we compute local error indicators to develop an adaptive space/time mesh refinement strategy. Numerical experiments verify our theoretical results and the proposed adaptive strategy. 相似文献
97.
98.
The electrochemical detection of BPA often requires modification of electrodes to overcome BPA′s slower kinetics and higher oxidation potential. This work reports a modification-free, paper electrode based on vacuum-filtered SWCNT thin film. The prepared electrode does not need to be polished or transferred into the conducting substrates. The linear sweep voltammetric detection showed a linear response from 0.5–10 μM and 25–100 μM with the experimental LOD of 1.0 μM (S/N=3). The interference study and good recovery percentage (93–105 %) in real water samples demonstrated the method‘s selectivity. The sensor can be promising for developing a simple, low-cost, portable, and paper-based BPA monitoring system. 相似文献
99.
Clemente-León M Coronado E Giménez-López MC Soriano-Portillo A Waerenborgh JC Delgado FS Ruiz-Pérez C 《Inorganic chemistry》2008,47(19):9111-9120
The syntheses, structures, and magnetic properties of the compounds of formula [Fe (III)(sal 2trien)] 2[Mn (II) 2(ox) 3].4H 2O.C 3H 7NO ( 1) and [In (III)(sal 2trien)] 2[Mn (II) 2(ox) 3].3H 2O.CH 3OH (2) are reported. The structure presents a homometallic 2D honeycomb anionic layer formed by Mn (II) ions linked through oxalate ligands and a cationic double layer of [Fe(sal 2trien)] (+) or [In(sal 2trien)] (+) complexes intercalated between the 2D oxalate network. The magnetic properties and M?ssbauer spectroscopy of 1 indicate the coexistence of a magnetic ordering of the Mn(II) oxalate network that behaves as a weak ferromagnet and a gradual spin crossover of the intercalated [Fe(sal 2trien)] (+) complexes. 相似文献
100.
The substitution of nucleobases in nucleic acid duplexes with ligands that have high affinity for transition metal ions creates metal-binding sites at specific locations within the duplexes. Several studies on the incorporation of metal ions into DNA and peptide nucleic acid (PNA) duplexes have suggested that the stability constant of the metal complex formed within the duplexes is a primary determinant of the thermal stability of the duplexes. To understand this relationship, we have synthesized two PNA monomers that carry the same ligand, namely 8-hydroxyquinoline, but have this ligand attached differently to the PNA backbone. The PNA monomers have been incorporated into PNA duplexes. UV and CD spectroscopy and calorimetric studies of the 8-hydroxyquinoline-PNA duplexes showed that the effect of the stability of the metal complex on the PNA duplexes was significantly modulated by the steric relationship between the complex and the duplex. This information is useful for the construction of hybrid inorganic-nucleic acid nanostructures. 相似文献