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Dong-Dong Zhou Jun Wang Pin Chen Yangyong He Jun-Xi Wu Sen Gao Zhihao Zhong Yunfei Du Dingyong Zhong Jie-Peng Zhang 《Chemical science》2021,12(4):1272
Rational manipulation of supramolecular structures on surfaces is of great importance and challenging. We show that imidazole-based hydrogen-bonded networks on a metal surface can transform into an isostructural coordination network for facile tuning of the pore size and guest recognition behaviours. Deposition of triangular-shaped benzotrisimidazole (H3btim) molecules on Au(111)/Ag(111) surfaces gives honeycomb networks linked by double N–H⋯N hydrogen bonds. While the H3btim hydrogen-bonded networks on Au(111) evaporate above 453 K, those on Ag(111) transform into isostructural [Ag3(btim)] coordination networks based on double N–Ag–N bonds at 423 K, by virtue of the unconventional metal–acid replacement reaction (Ag reduces H+). The transformation expands the pore diameter of the honeycomb networks from 3.8 Å to 6.9 Å, giving remarkably different host–guest recognition behaviours for fullerene and ferrocene molecules based on the size compatibility mechanism.A hydrogen-bonded network on a Ag(111) surface can transform into an isostructural Ag(i) coordination network, giving drastically different host–guest recognition behaviours. 相似文献
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Using the static exchange‐correlation charge density concept, the total integrated exchange‐charge density function is calculated within the nonrelativistic spin‐restricted exchange‐only (i) optimized effective potential model, and (ii) nonvariational local potential derived from the exchange‐only work potential within the quantal density functional theory, for the ground‐state isoelectronic series: Ga+, Zn, Cu?; In+, Cd, Ag?; and Tl+, Hg, Au?. The difference between the exchange charge density function derived from these potentials is employed to evaluate the first‐order correlation‐kinetic contribution to the integrated exchange charge density. This contribution is found to be important for both the intra‐ and inter‐shell regions. Screening effects on the contribution due to the nd10 (n = 3–5) subshells are discussed through comparisons with similar calculations on Ca, Sr, and Ba, wherein nd10 electrons are absent. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
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The raw material used in the production of fetilizers is phosphate ore containing various amounts of naturally radioactive elements. During phosphate ore processing, owing to chemical properties of radium, practically all226Ra gets incorporated into phosphogypsum and becomes the main source of radioactivity. This study was carried out in a fertilizer factory in central Croatia, which may represent a site of significant environmental contamination due to fertilizer production and phosphogypsum deposition in the area. The purpose of this paper was to determine whether ingestion of drinking water in this area poses a health risk for the inhabitants. The results of our study confirmed the occurrence of226Ra in elevated concentrations in the samples of trickling waters. However, concurrent analyses of drinking water indicated that the risk of adverse health effects for the population living in the vicinity of a phosphate fertilizer plant is negligible. 相似文献
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土壤胡敏酸的^13C核磁共振研究 总被引:1,自引:0,他引:1
胡敏酸(HA)是土壤有机质的重要组分,其结构性质与土壤形成和肥力特性有密切关系,长期以来一直是土壤化学研究的难点和重点之一。NMR是研究HA结构的有效手段。自Bar-ton和Schnitzer(1963)首次用~1H NMR研究土壤有机质以来,国外已先后应用~1H、~(13)C NMR和CP-MAS-~(13)C NMR等对土壤及其它来源的HA进行了许多研究,并取得引人注目的进展。但在国内,这方面研究还刚刚开始。本文应用~(13)C NMR方法对东北几种主要耕作土壤以及泥炭和猪粪的HA进行了结构表征,为土壤腐殖酸化学的基础研究提供了资料。 相似文献
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A titrimetric method using EDTA for the determination of potassium, rubidium, cesium, thallium and ammonium has been developed. These cations are precipitated as M2Ag[Co(NO2)6] and the blue cobalt thiocyanate complex in acetone-water mixed system is titrated with EDTA. Milligram quantities have been determined in the present work 相似文献
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以2-巯基苯并咪唑为保护剂,聚乙烯吡咯烷酮为稳定剂,水合肼为还原剂,“一锅法”合成2-巯基苯并咪唑保护的,高稳定性、强荧光、大斯托克斯位移的铜纳米团簇(Cu NCs),并用于检测水样中的银离子含量。采用透射电子显微镜(TEM)和X射线光电子能谱(XPS)对铜纳米团簇的结构进行表征,通过荧光光谱和紫外可见光谱对其光学性能进行研究。研究表明:该铜纳米团簇的最大激发和发射波长分别为340和558 nm,在日光灯和紫外灯下分别为无色和橙色。Cu NCs具有较高的分散性,尺寸大小为2~3 nm。在最佳反应条件下,铜纳米团簇可以选择性地被银离子猝灭,且灵敏度高,线性范围为1~40μmol/L,检测限为0.5μmol/L。该方法用于检测实际水样(自来水、湖水)中银离子的浓度,结果令人满意,表明在环境监测中有非常高的应用价值。 相似文献
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