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21.
Several novel routes for the immobilization of modified Cu(salicylaldimine) complexes on commercially available silica are described. New pulse electron paramagnetic resonance (EPR) and electron-nuclear double resonance sequences, which provide more detailed information than that available previously, in combination with continuous wave EPR, allow a definitive assignment of the geometry at the copper center in the immobilized Cu(salicylaldimine). Immobilization of the modified Cu(salicylaldimine) on silica was followed in situ by monitoring the intensity of the characteristic free- and metal-coordinated imine bands as a function of time using attenuated total reflectance IR spectroscopy. On the basis of these studies, the outcome of the Schiff base condensation of Cu-bis(salicylaldehyde) with gamma-aminopropyl-modified silica gel is shown to provide immobilized trans-O(2)N(2)- and O(3)N-coordinated immobilized Cu(salicylaldimine)-type compounds. In addition, trans-O(2)N(2)- or O(3)N-coordinated copper centers are selectively prepared on silica by controlling the aminopropyl modifier loading, thus opening a route to compounds not available by conventional synthesis. The O(3)N-coordinated Cu(salicylaldimine)-type compound on silica was investigated as a precursor for the synthesis of a tethered chiral Cu(salicylaldimine) via reaction of the coordinated carbonyl group with (R)-(+)-alpha-methylbenzylamine. Supported Cu(salicylaldimine) was also prepared via the immobilization of the appropriate silylethoxy-modified homogeneous precursor on silica gel. Precursors and silica-supported Cu(salicylaldimine) materials have been fully characterized. Comparisons are drawn with related Cu(salicylaldimine) immobilized in silica aerogels. 相似文献
22.
Craig G. Wall Eamonn F. Healy Marye Anne Fox 《International journal of quantum chemistry》1992,44(4):543-548
To explain observed electron transfer rates between the terminal aromatic moieties in the arylsubstituted alanine dimer 1 , a conformational analysis of the dipeptide was performed using a standard molecular mechanics force field. The resulting low-energy conformers could conveniently be grouped into two families with an average energy difference of ca. 2 kcal mol?1 and populations of 64% and 30%, respectively. These results correlate well with the 78:22 ratio of the two experimentally distinguishable decay processes for the radical anion of 1 . © 1992 John Wiley & Sons, Inc. 相似文献
23.
The first salts of phosphinoarsonium, diarsonium, and phosphinodiarsonium ions are obtained from reaction mixtures of a chlorophosphine, a tertiary arsine, and a chloride-abstracting agent. The versatile synthetic approach has implications in the development of a wide variety of interpnictogen compounds. 相似文献
24.
Vrishali Subramanian Elena Semenzin Danail Hristozov Alex Zabeo Ineke Malsch Eamonn McAlea Finbarr Murphy Martin Mullins Toon van Harmelen Tom Ligthart Igor Linkov Antonio Marcomini 《Journal of nanoparticle research》2016,18(4):89
The significant uncertainties associated with the (eco)toxicological risks of engineered nanomaterials pose challenges to the development of nano-enabled products toward greatest possible societal benefit. This paper argues for the use of risk governance approaches to manage nanotechnology risks and sustainability, and considers the links between these concepts. Further, seven risk assessment and management criteria relevant to risk governance are defined: (a) life cycle thinking, (b) triple bottom line, (c) inclusion of stakeholders, (d) risk management, (e) benefit–risk assessment, (f) consideration of uncertainty, and (g) adaptive response. These criteria are used to compare five well-developed nanotechnology frameworks: International Risk Governance Council framework, Comprehensive Environmental Assessment, Streaming Life Cycle Risk Assessment, Certifiable Nanospecific Risk Management and Monitoring System and LICARA NanoSCAN. A Sustainable Nanotechnology Decision Support System (SUNDS) is proposed to better address current nanotechnology risk assessment and management needs, and makes. Stakeholder needs were solicited for further SUNDS enhancement through a stakeholder workshop that included representatives from regulatory, industry and insurance sectors. Workshop participants expressed the need for the wider adoption of sustainability assessment methods and tools for designing greener nanomaterials. 相似文献
25.
Eamonn F. Murphy Ramaswamy Murugavel Herbert W. Roesky Mathias Noltemeyer Hans-Georg Schmidt 《无机化学与普通化学杂志》1996,622(3):579-582
[{Cp*ZrF2Br}4] is conveniently prepared in high yield from the reaction of [{Cp*ZrF3}4] with four equivalents of Me3SiBr. In contrast the reaction of [{Cp*ZrF3}4] with Me3SiI under identical reaction conditions leads to a mixture of [Cp*ZrI3] and unreacted [{Cp*ZrF3}4]. The crystal structure of [{Cp*ZrF2Br}4] has been determined by X-ray diffraction studies. The compound crystallizes in the orthorhombic crystal system [a = 9.325(1), b = 23.483(3), c = 27.016(5) Å, α = β = γ = 90°, space group Ibam, Z = 4]. The tetrameric core structure of [{Cp*ZrF2Br}4] contains four zirconium atoms linked by alternating single and triple fluorine bridges. One terminal bromine atom is bonded to each zirconium. 1H and 19FNMR spectroscopic data and structural features of the title compound are compared with those for the mixed fluoro-chloro complexes [{Cp*ZrF2Cl}4], [{Cp*ZrF2Cl}2{Cp*ZrFCl2}2] and the trifluoro complex [{Cp*ZrF3}4]. 相似文献
26.
Chitnis SS Peters B Conrad E Burford N McDonald R Ferguson MJ 《Chemical communications (Cambridge, England)》2011,47(45):12331-12333
Reactions of trimethylphosphine or diphosphines with SbCl(3) in the presence of AlCl(3) or Me(3)SiSO(3)CF(3) give ligand stabilized stibenium and stibinidenium cations. The geometry at each antimony center reveals a variety of environments for antimony that describes new bonding and highlights new directions in the chemistry of the pnictogen elements. 相似文献