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This review will describe the ongoing efforts being made to incorporate organometallic fragments into the framework of dendrimers. While purely dendritic organic molecules are well known and well studied, species incorporating organometallic moieties potentially offer many benefits that are not available to only organic containing dendrimers. For example, catalytic or redox active organometallic functions can be included in the dendritic framework and impart these characteristics onto the dendrimer. This report will give an overview of the latest developments in this field by highlighting selected examples that detail novel synthetic strategies or dendrimer construction methodologies, interesting practical applications or address specific problems associated with organometallic dendrimers. 相似文献
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J. B?chler J. Bartke H. Bia?kowska R. Bock D. Brinkmann R. Brockmann P. Buncic S. I. Chase I. Derado V. Eckardt et al. 《Zeitschrift fur Physik C Particles and Fields》1994,61(4):551-561
The intermittency phenomenon is investigated in proton-gold, oxygen-gold, sulphur-gold and sulphur-sulphur collisions at 200 GeV per nucleon. The data were taken with the NA 35 streamer chamber detector at the CERN SPS. The data samples are carefully corrected for double counting of tracks and for contamination from photon conversions, particle decays and secondary interactions. The analysis is carried out in terms of factorial moments, using a new definition, and of correlation integrals. Both methods show the presence of nonstatistical fluctuations (intermittency). The main conclusions are: The observation of the effect for pairs of hadrons with negative charges and its near absence for pairs of opposite charges is consistent with the assumption that Bose-Einstein correlations yield the dominant contribution. The intermittency effect is not proportional to (dn/dy)–1 which would be expected in superposition models. The measured relation between the second and third factorial moment for negative hadrons indicates that genuine 3-particle correlations are small. The predictions of a Monte Carlo simulation which is based on the Lund Fritiof model with the inclusion of Bose-Einstein correlations agree with the experimental results.Deceased 相似文献
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This paper reports the results of the interlaboratory peer validation study of AOAC Peer-Verified Method (PVM) 1:2,000 for the determination of niacin in infant formula by solid-phase extraction/liquid chromatography. We have used a Data Quality Objectives (DQO) approach to address not only method variability and robustness but also accuracy of data through the use of an appropriate reference material in conjunction with the interlaboratory validation study. Our DQO included the following: (1) statistical agreement of analytical results and quantitative recovery between 2 collaborating laboratories; (2) the repeatability relative standard deviation (RSDr) values and the HORRAT (Horwitz ratio) obtained (1.07), which satisfied the criteria of the Horwitz "limits of acceptability" at the analyte level present; (3) validation of lack of interference; and (4) accuracy agreement within assigned values for a certified reference material. National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1846 Infant Formula, with a certified value of 63.3 +/- 7.6 microg/g for niacin content, was used as a test material for collaborative study and accuracy assessment. Niacin values obtained by the originating laboratory were 59.7 +/- 4.0 microg/g (95% confidence interval [CI] = 1.4 microg/g with a relative standard deviation [RSD] of 6.7%) and by the peer laboratory were 56.6 +/- 6.6 microg/g (95% CI = 4.1 microg/g, with an RSD of 11.7%). Statistical evaluation using the means equivalence test showed that nicotinic acid values obtained by the peer laboratory were equivalent to those values obtained by the originating laboratory. Linear calibration curves and quantitative recovery were obtained. Integration of the PVM process with a readily available certified reference material gives the user confidence in the accuracy of the data generated by the method through traceability to the reference material used. 相似文献
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Serenella Medici Marcella Gagliardo ScottB. Williams PrestonA. Chase Serafino Gladiali Martin Lutz AnthonyL. Spek GerardP.M. vanKlink Gerard vanKoten 《Helvetica chimica acta》2005,88(3):694-705
Achiral P‐donor pincer‐aryl ruthenium complexes ([RuCl(PCP)(PPh3)]) 4c , d were synthesized via transcyclometalation reactions by mixing equivalent amounts of [1,3‐phenylenebis(methylene)]bis[diisopropylphosphine] ( 2c ) or [1,3‐phenylenebis(methylene)]bis[diphenylphosphine] ( 2d ) and the N‐donor pincer‐aryl complex [RuCl{2,6‐(Me2NCH2)2C6H3}(PPh3)], ( 3 ; Scheme 2). The same synthetic procedure was successfully applied for the preparation of novel chiral P‐donor pincer‐aryl ruthenium complexes [RuCl(P*CP*)(PPh3)] 4a , b by reacting P‐stereogenic pincer‐arenes (S,S)‐[1,3‐phenylenebis(methylene)]bis[(alkyl)(phenyl)phosphines] 2a , b (alkyl=iPr or tBu, P*CHP*) and the complex [RuCl{2,6‐(Me2NCH2)2C6H3}(PPh3)], ( 3 ; Scheme 3). The crystal structures of achiral [RuCl(equation/tex2gif-sup-3.gifPCP)(PPh3)] 4c and of chiral (S,S)‐[RuCl(equation/tex2gif-sup-6.gifPCP)(PPh3)] 4a were determined by X‐ray diffraction (Fig. 3). Achiral [RuCl(PCP)(PPh3)] complexes and chiral [RuCl(P*CP*)(PPh3)] complexes were tested as catalyst in the H‐transfer reduction of acetophenone with propan‐2‐ol. With the chiral complexes, a modest enantioselectivity was obtained. 相似文献
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Prof. Dr. Ronald Griessen Dr. Christiaan Boelsma Herman Schreuders Prof. Dr. Chase P. Broedersz Dr. Robin Gremaud Prof. Dr. Bernard Dam 《Chemphyschem》2020,21(15):1632-1643
Enthalpy-entropy compensation (EEC) is very often encountered in chemistry, biology and physics. Its origin is widely discussed since it would allow, for example, a very accurate tuning of the thermodynamic properties as a function of the reactants. However, EEC is often discarded as a statistical artefact, especially when only a limited temperature range is considered. We show that the likeliness of a statistical origin of an EEC can be established with a compensation quality factor (CQF) that depends only on the measured enthalpies and entropies and the experimental temperature range. This is directly derived from a comparison of the CQF with threshold values obtained from a large number of simulations with randomly generated Van ‘t Hoff plots. The value of CQF is furthermore a direct measure of the existence of a genuine isoequilibrium or isokinetic relationship. 相似文献