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71.
Crystals of a new aqueous rare earth borate Sm3[B13O22(OH)3](OH) · 3H2O, space group P2/c, are obtained under hydrothermal conditions. The structure is determined by the heavy-atom method without preliminary knowledge of the chemical formula. The anionic radical is a boron-oxygen sheet in which two corrugated layers are related by centers of inversion. An independent layer is akin to pentaborate layers; it differs from the layer in (Nd0.925Na0.075)Nd[B9O15(OH)2]Cl0.85 · 2.65H2O by an additional branch in the form of a 4: (3[2?? + 1T] + 1??) group. The intersheet space and large holes of the sheet accommodate Sm atoms, (OH) groups, and water molecules. The new Sm-borate and the related Nd-borate are polyborates (megaborates) with complex anionic radicals. In the Sm-borate, the new two-dimensional [B13O22(OH)3]??? complex anionic radical of the 13{(4: [2T + 2??])?? + (5: [3T + 2??] + 4: (3[2?? + 1T] +1??))??}??? formula is built of three different blocks, unlike the [B9O15(OH)2]??? radical of the 9{(4: [2T + 2??])?? + (5: [3T + 2??])??}??? formula in the Nd-borate, which consists of two blocks. The rule of the inverse relationship between the polymerization degrees of the boron-oxygen radical and rare earth polyhedra holds for both borates. 相似文献
72.
73.
Lemouchi C Barrès AL Mézière C Rondeau D Zorina L Wzietek P Batail P 《Dalton transactions (Cambridge, England : 2003)》2011,40(32):8075-8078
A polar function like pyridine increases the polarity difference between mono- and disubstituted 1,4-bis(trimethylsilylethynyl)bicyclo[2.2.2]octane cores allowing for their ready separation by chromatography, affording two dissymmetrical ligands illustrated in metal-rotor hybrids like a corner-shaped mononuclear complex, an octahedral hexanuclear metal complex, and a framework solid with a rather slow rotator. 相似文献
74.
Capel VL Dillon KB Goeta AE Howard JA Monks PK Probert MR Shepherd HJ Zorina NV 《Dalton transactions (Cambridge, England : 2003)》2011,40(8):1808-1816
Some new phosphorus(III) derivatives Ar(2)PX (X = Br, Cl, F or H), ArPX(2) (X = Br or Cl), Ar(3)P and Ar(t)BuPCl, with the 2,5-bis(trifluoromethyl)phenyl (Ar) substituent on phosphorus, have been prepared, and characterised by (31)P and (19)F NMR solution-state spectroscopy. The complexing ability of Ar(2)PX, Ar(3)P and Ar(t)BuPCl towards the dimeric platinum(II) complexes [PtY(μ-Y)(PEt(3))](2) (Y = Cl or Br, the latter for X = Br only) has also been investigated. Single-crystal X-ray diffraction studies at low temperature have been carried out for Ar(3)P, Ar(2)PCl and the hydrolysis or oxidation products Ar(2)P(H)OH and Ar(2)P(O)OH. The structures of Ar(3)P and Ar(2)PCl are particularly interesting as in each compound the geometry around P is approximately octahedral. In Ar(3)P there are three short contacts to fluorine as well as the three bonded C atoms for both of the independent molecules in the unit cell. For Ar(2)PCl there are two short P-F contacts, and the octahedron is completed by a weak P-P interaction to a neighbouring molecule. In both instances the lone pair on the P(III) centre appears to be stereochemically inactive, and does not play a significant role in the structure. 相似文献
75.
V. A. Reshetov T. E. Zorina M.-A. D’Hallewin L. N. Bolotina V. P. Zorin 《Journal of Applied Spectroscopy》2011,78(1):103-109
Three approaches to analyzing the rate of release of the photosensitizer meta-tetrahydroxyphenylchlorin (mTHPC) from unilaminar
lipid vesicles (ULV) in model biological systems are studied: by excitation energy transfer from probe diphenylhexatriene
to mTHPC, by the fluorescence anisotropy of mTHPC, and by photoinduced quenching of the fluorescence of mTHPC. Each of these
methods has its characteristic range of sensitivity for measurements of the local concentration of mTHPC in ULV. Fluorescence
anisotropy can be used for quantitative determination of the mTHPC yield from ULV for mTHPC:lipid ratios of 1:100 to 1:1000,
determining the efficiency of fluorescence quenching of diphenylhexatriene for ratios <1:200, and photoinduced quenching for
ratios of 1:10–1:500. 相似文献
76.
Lemouchi C Vogelsberg CS Zorina L Simonov S Batail P Brown S Garcia-Garibay MA 《Journal of the American Chemical Society》2011,133(16):6371-6379
As a point of entry to investigate the potential of halogen-bonding interactions in the construction of functional materials and crystalline molecular machines, samples of 1,4-bis(iodoethynyl)bicyclo[2.2.2]octane (BIBCO) were synthesized and crystallized. Knowing that halogen-bonding interactions are common between electron-rich acetylenic carbons and electron-deficient iodines, it was expected that the BIBCO rotors would be an ideal platform to investigate the formation of a crystalline array of molecular rotors. Variable temperature single crystal X-ray crystallography established the presence of a halogen-bonded network, characterized by lamellarly ordered layers of crystallographically unique BIBCO rotors, which undergo a reversible monoclinic-to-triclinic phase transition at 110 K. In order to elucidate the rotational frequencies and the activation parameters of the BIBCO molecular rotors, variable-temperature (1)H wide-line and (13)C cross-polarization/magic-angle spinning solid-state NMR experiments were performed at temperatures between 27 and 290 K. Analysis of the (1)H spin-lattice relaxation and second moment as a function of temperature revealed two dynamic processes simultaneously present over the entire temperature range studied, with temperature-dependent rotational rates of k(rot) = 5.21 × 10(10) s(-1)·exp(-1.48 kcal·mol(-1)/RT) and k(rot) = 8.00 × 10(10) s(-1)·exp(-2.75 kcal·mol(-1)/RT). Impressively, these correspond to room temperature rotational rates of 4.3 and 0.8 GHz, respectively. Notably, the high-temperature plastic crystalline phase I of bicyclo[2.2.2]octane has a reported activation energy of 1.84 kcal·mol(-1) for rotation about the 1,4 axis, which is 24% larger than E(a) = 1.48 kcal·mol(-1) for the same rotational motion of the fastest BIBCO rotor; yet, the BIBCO rotor has three fewer degrees of translational freedom and two fewer degrees of rotational freedom! Even more so, these rates represent some of the fastest engineered molecular machines, to date. The results of this study highlight the potential of halogen bonding as a valuable construction tool for the design and the synthesis of amphidynamic artificial molecular machines and suggest the potential of modulating properties that depend on the dielectric behavior of crystalline media. 相似文献
77.
78.
Synthesis of 2‐(Selenophen‐2‐yl)pyrroles and Their Electropolymerization to Electrochromic Nanofilms
Boris A. Trofimov Prof. Dr. Elena Yu. Schmidt Dr. Albina I. Mikhaleva Prof. Dr. Cristina Pozo‐Gonzalo Jose A. Pomposo Maitane Salsamendi Nadezhda I. Protzuk Dr. Nadezhda V. Zorina Dr. Andrey V. Afonin Dr. Alexander V. Vashchenko Dr. Ekaterina P. Levanova Dr. Galina G. Levkovskaya Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(26):6435-6445
Bridging pyrrole and selenophene chemistries : Molecular assemblies have been developed that allow scrutiny of the electronic communication between pyrrole and selenophene nuclei. Divergent syntheses of 2‐(selenophen‐2‐yl)pyrroles and their N‐vinyl derivatives from available 2‐acylselenophenes and acetylenes in a one‐pot procedure have been devised (see scheme), which provide access to these exotic heterocyclic ensembles.
79.
A method is proposed for the formation of porous structures in polymers. The method is based on the phase separation of two
polymers in a blend and selective degradation of one of them. Polymers hydrolyzable at a high rate in alkaline media (polyesters
of oxalic acid) are synthesized, and their hydrolytic degradation and phase separation in mixed solutions with a polylactide
are investigated. Porous polylactide samples are prepared by the selective hydrolysis of polylactide-polyoxalate blends. 相似文献
80.