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91.
Marcel Gielen 《Theoretical chemistry accounts》1982,61(1):21-28
The numbers of valence structures (NVS) and the valence state indexes (VSI) have been determined for a series of 2n framework electron clustersviz. polyhedral boron subhalides B
n
X
n
(n=6–12) and compared with those obtained for the parent B
n
H
n
2– dianions. The VSI does not reflect the experimental stabilities. 相似文献
92.
Jeukens CR Jonkheijm P Wijnen FJ Gielen JC Christianen PC Schenning AP Meijer EW Maan JC 《Journal of the American Chemical Society》2005,127(23):8280-8281
We have prepared 5 nm diameter, micrometer long tetra(p-phenylenevinylene) (OPV)-based nanofibers on a graphite surface. The fluorescence emission of an individual fiber shows a profound polarization over its entire length that directly corresponds to its orientation on the substrate. Quantitative analysis of the fluorescence polarization, including the depolarizing effect of the underlying graphite, evidences the high degree of organization within chiral fibers with the OPV molecules perpendicular to the fiber axis. The control of the internal order within self-assembled fibers, and the ability to measure it, is a crucial step to obtain uniform organic fibers that can be applied in nanosized electronics at room temperature. 相似文献
93.
The 119Sn cross polarization‐magic angle spinning NMR spectrum of bis[1,3‐bis(3‐oxapentamethylenecarbamoylthioacetato)‐1,1,3,3‐tetrabutyl‐1,3‐distannoxane], {[(C4H9)2SnO2CCH2SC(O)N(CH2CH2)2O]2O}2, which consists of two resonances of similar chemical shifts and symmetry (δiso = −152, −202 ppm; asymmetry, κ = 0.38), implies the existence of two five‐coordinate tin sites in the centrosymmetric dimer. The assignment has been corroborated by X‐ray diffraction analysis on the compound that has been crystallized from ethanol; the crystal structure shows two tin atoms in cis‐C2SnO3 trigonal‐bipyramidal coordination [C‐Sn‐C = 131.5(1), 131.3(2) °]. The analysis also reveals the presence of two lattice ethanol molecules that are hydrogen‐bonded to the dimer [OO = 2.779(5) Å]. When exposed to air, the distannoxane loses ethanol. The unsolvated distannoxane is more active than cis‐platin when screened against MCF‐7 (mammary cancer), EVSA‐T (mammary cancer), WiDr (colon cancer), IGROV (ovarian cancer), M19 MEL (melanoma), A498 (renal cancer) and H226 (lung cancer) cell lines. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
94.
Mala Nath Sandeep Pokharia Xueqing Song George Eng Marcel Gielen Martine Kemmer Monique Biesemans Rudolph Willem Dick de Vos 《应用有机金属化学》2003,17(10):823-823
The original article to which these Errata refer was published in the journal Applied Organometallic Chemistry 2003; 17 (5): 305–314. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
95.
Shashwati Sen DK Aswal Ajay Singh TV Chandrasekhar Rao KP Muthe JC Vyas LC Gupta SK Gupta VC Sahni 《Pramana》2002,58(5-6):867-870
The MgB2 superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties.
The upper critical field, irreversibility line and critical current density have been determined using magnetization data.
The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition.
The surface analysis using X-ray photoelectron spectroscopy shows that MgB2 is sensitive to atmospheric degradation. 相似文献
96.
97.
A comparison is given between a Mössbauer spectroscopy determination and the classical chemical analysis of the Fe2+ content in SiO2Na2OFe2O3 glass systems, for different iron concentrations, and for 16.0 and 24.0 wt% Na2O respectively. The agreement between Mössbauer analysis and chemical analysis is good only for large Fe2O3 contents, while for small Fe2O3 contents the Mössbauer analysis gives a much larger Fe2+/(Fe2+ + Fe3+) ratio than the chemical analysis: a physical reason is given for this fact. The Fe2O3 content below which Fe2+ becomes predominant in glass is rather sharply defined, and a qualitative explanation is proposed to account for this rapid transition from Fe3+ to Fe2+. 相似文献
98.
Rudolph Willem Hassan Dalil Monique Biesemans Jos C. Martins Marcel Gielen 《应用有机金属化学》1999,13(8):605-608
The reaction of hexafluoro‐2,2‐bis(4‐carboxyphenyl)propane with tetrabutyldipropoxydistannoxane, formed in situ from dibutyltin oxide and n‐propanol in benzene, yields a compound the structure of which is a strained macrocycle with a single dicarboxylate moiety. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
99.
100.
The bimolecular halodemetallation of substituted cyclopropyltrialkyltins is stereospecific, and proceeds with retention of the configuration at carbon in methanol, acetic acid and chlorobenzene. The kinetic study confirms the hypothesis which was based on results for the R′SnR3 series, and shows the participation of the ring orbitals in the rate determining step of the reaction. 相似文献