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161.
Barberá J Bardají M Jiménez J Laguna A Martínez MP Oriol L Serrano JL Zaragozano I 《Journal of the American Chemical Society》2005,127(25):8994-9002
A synthetic strategy has been developed to prepare cyclotriphosphazenes that bear polycatenar aromatic esters as promesogenic units linked to phosphorus atoms. The microsegregation of the rigid and flexible parts of the system and the space-filling properties are the driving forces that determine the kind of mesomorphism exhibited by the organocyclotriphosphazenes. Mesogenic units that contain only one terminal alkyl chain give rise to calamitic mesomorphism, since the molecules are arranged to give a cylindrical superstructure with the aromatic promesogenic cores elongated in a manner approximately perpendicular to the cyclotriphosphazene ring. On the other hand, mesogenic units that contain three long terminal chains exhibit columnar mesophases. In this case, a discotic structure consisting of promesogenic cores arranged approximately parallel to the cyclotriphosphazene ring can explain the columnar organization. The X-ray diffraction patterns corresponding to the Col(h) mesophase of the cyclotriphosphazene with dodecyloxy chains (8) indicate the presence of helical ordering, which was confirmed for a homologous compound bearing stereogenic centers on two of the terminal chains (11). All of the synthesized phosphazenes show a high thermal stability. 相似文献
162.
163.
A convex geometric graphG of ordern consists of the set of vertices of a plane convexn-gonP together with some edges, and/or diagonals ofP as edges. CallG 1-free ifG does not havel disjoint edges in convex position. We answer the following questions:
- What is the maximum possible number of edges ofG ifG isl-free (as a function ofn andl)?
- What is the minimum possible number of edges ofG ifG isl-free and saturated, i.e., ifG∪{e} is notl-free for any edge or diagonale ofP that is not, already inG..
164.
165.
Gemma Aragay Josefina Pons Jordi García-Antón Xavier Solans Mercè Font-Bardia Josep Ros 《Journal of organometallic chemistry》2008,693(21-22):3396-3404
The synthesis of two N-alkylaminopyrazole ligands, 1-[2-(diethylamino)ethyl]-3,5-diphenylpyrazole (L1) and 1-[2-(dioctylamino)ethyl]-3,5-diphenylpyrazole (L2), is reported. These ligands present, a priori, one pyrazole nitrogen and one amine nitrogen as potential donor atoms. However, in the reaction of the ligands (L1 and L2) with [PdCl2(CH3CN)2] one of the Cphenyl atoms can also behave as a donor atom. As a result, we have obtained the formation of three different compounds for each one of the ligands: chelated ([PdCl2(L)] L = L1 (1a), L2 (2a)), zwitterionic ([PdCl3(LH)] LH = LH1 (1b), LH2 (2b)), and cyclopalladated compounds ([PdCl(LC)] (LC = LC1 (1c), LC2 (2c)). The solid-state structures for 1a, 1b and 1c were determined by single crystal X-ray diffraction methods. The potentially [C,N,N′]? ligand is coordinated through the Npz and the Namino to the metal atom for 1a, through the Npz for 1b, and through the Npz, the Namino and a Cphenyl for 1c. 相似文献
166.
Antonio de Leon Josefina Pons Jordi García-Antón Xavier Solans Mercè Font-Bardia Josep Ros 《Journal of chemical crystallography》2007,37(12):801-805
Abstract The reaction of the potentially tetradentate ligand 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn) with [PtCl2(CH3CN)2] yields a mixture of complexes, where the ligand acts as bidentate SS, or tetradentate 2NS or NSSN. This mixture of complexes
SS, 2NS, and NSSN was crystallized with dichloromethane/n-pentane (1:1) and crystals of [Pt(bddn)]Cl2 (isomer NSSN) were obtained. The complex has been characterized by elemental analyses, mass spectrometry, conductivity, IR,
1H, 13C{1H}, 1H{195Pt}, 195Pt{1H}NMR, HSQC and NOESY spectroscopies, and X-ray diffraction. Compound [PtCl2(bddn)] · 3.5H2O crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 15.430(7) ?, b = 17.405(4) ?, c = 18.887(7) ?, β = 91.24(2)°, V = 5071(3) ?3, Z = 4, R
1 = 0.0354, wR2 = 0.1034. This compound consist of discrete cations [Pt(bddn)]2+, Cl− anions and water molecules of crystallization. The platinum(II) is tetracoordinated by two azine nitrogen atoms and two sulfur
atoms of the thioether-pyrazole ligand, in a distorted square planar geometry.
Graphical Abstract
Synthesis, Structural Characterization and Spectroscopic Properties of [Pt(bddn)]Cl
2
· 3.5H
2
O (bddn = 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane)
Antonio de Leon, Josefina Pons*, Jordi García-Antón, Xavier Solans, Mercè Font-Bardia, Josep Ros*
Reaction of the ligand 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn) with [PtCl2(CH3CN)2], yields a mixture of complexes. The mixture was crystallized with dichloromethane/pentane (1:1) and crystals of [Pt(bddn)]Cl2 · 3.5 H2O was obtained.
Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users. 相似文献
167.
In this work it a strong evidence of the hydrated electrons production was shown in a film of condensed water, by directing the injection of electrons in localized and/or delocalized water electronic states using a system of high voltage made in laboratory. The results show that the water layers on the silica particles are electrically charged by injection of electrons from a metal electrode when silica is placed in high electric field. This charging process also appears to depend on the thickness of these water layers and of the spatial arrangement required by the silica surface. 相似文献
168.
Britta Lindholm-Sethson Josefina Nyström Martin Malmsten Lovisa Ringstad Andrew Nelson Paul Geladi 《Analytical and bioanalytical chemistry》2010,398(6):2341-2349
Electrochemical impedance spectroscopy plays an important role in biosensor science thanks to the possibility of finding specific
information from processes with different kinetics at a chosen electrode potential in one experiment. In this paper we briefly
discuss label-free impedimetric biosensors described in the literature. A novel method for neutral interpretation of impedance
data is presented that includes complex number chemometrics. Three examples are given based on impedance measurements on synthetic
biomembranes, in this case a lipid monolayer deposited on a mercury electrode. The interaction of various compounds with the
monomolecular lipid layer is illustrated with the following: (1) different concentrations of magainin (Geladi et al. in Proc. Int. Fed. Med. Biomed. Eng. 9:219–220, 2005); (2) different derivatives of gramicidin A (Lindholm-Sethson et al. in Langmuir 24:5029–5032, 2007), and (3) an antimicrobial peptide (Ringstad et al. in Langmuir 24:208–216, 2008). 相似文献
169.
Antonio de León Josefina Pons Jordi García-Antón Xavier Solans Mercè Font-Bardía Josep Ros 《Polyhedron》2009
Mononuclear palladium(II) complexes containing a pyrazole-thioether ligand, with general formula trans-[Pd(X)2(bddo)] (X = CN− (1), SCN− (2) or N3− (3); bddo = 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane), have been prepared. Similar reactivity carried out with pyridine or triphenylphosphine has been assayed. When pyridine is used, a mixture of [Pd(bddo)(py)2](BF4)2 ([4](BF4)2) and [Pd(bddo)](BF4)2 is obtained. When triphenylphosphine is used, only [Pd(bddo)](BF4)2 is obtained. The complexes have been characterised by elemental analyses, conductivity measurements, IR and NMR spectroscopies. X-ray crystal structure of trans-[Pd(SCN)2(bddo)] (2) is presented. In this complex the metal atom is coordinated by the two azine nitrogen atoms of the pyrazole rings and two SCN− anions in trans disposition. 相似文献
170.
Ana Lilia Ocampo Julio César Aguilar Eduardo Rodríguez de San Miguel Minerva Monroy Pedro Roquero Josefina de Gyves 《Journal of membrane science》2009
The preparation and characterization of new polymer inclusion membranes (PIMs) for proton transport is described. PIMs were prepared with different polymeric cellulose-based compounds and PVC as supports, tris(2-butoxyethyl)phosphate (TBEP) and 2-nitrophenyl octyl ether (NPOE) as plasticizers and dinonylnaphthalenesulfonic acid (DNSA) and dinonylnaphthalenedisulfonic acid (DNDSA) as carriers. The effects of the nature and content of the supports, plasticizers and carriers on membrane proton conductivity was studied using electrochemical impedance spectroscopy (EIS). This technique was also used to evaluate the chemical stability of a CTA–NPOE–DNDSA membrane while its selectivity was monitored with respect to sodium and calcium ions through counter-transport experiments. DSC and TGA techniques were used to determine the thermal stability of these membranes. A PIM based on CTA–DNDSA–NPOE showed the highest proton conductivity (3.5 mS/cm) with no variation of its behavior during 2 months of evaluation. FTIR characterization did not show structural changes of the membrane in this period of time. Thermal analysis indicates that it is stable up to 180 °C. An empirical functional relationship between PIM resistance and composition indicates that increasing plasticizer and carrier concentrations enhances the conductivity of the membranes, while increasing CTA content tends to decrease this property. Transport experiments showed a good selectivity of the CTA–DNDSA–NPOE membrane for protons over calcium or sodium ions. 相似文献