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111.
Cadmium colloids have been prepared by Chemical Liquid Deposition (CLD). The metal is evaporated to yield atoms which are solvated at liquid nitrogen temperature, and upon warming, stable liquid colloids are formed with particle size ranging between 25–100 Å. Zeta potentials were calculated according to the conversion of Hunter and the Hückel equation, for ethanol and dimethyl sulphoxide. UV/VIS measurement of most of the black colloids showed absorption band around 280 nm. For comparison, we prepared CdS colloid with size 400–625 Å. The colloids are stable to oxidation in air and/or oxygen bubbling. The synthesis of colloids and films from Cd with acetone, 2-butanone, ethanol, 2-propanol, 2-methoxyethanol, DMF and DMSO is reported. Transmission Electron Microscopy (TEM) allows us to determine particle size. 相似文献
112.
The absorption spectra and emission spectral band shapes of several polypyridine-ligand (PP) bridged bis-ruthenium(II) complexes imply that the Ru(II)/Ru(III) electronic coupling is weak in their lowest energy metal to ligand charge transfer (MLCT) excited states. Many of these PP-bridging ligands contain pyrazine moieties and the weak electronic coupling of the excited states contrasts to the strong electronic coupling inferred for the correlated mixed-valence ground states. Although the bimetallic complexes emit at significantly lower energy than their monometallic analogs, the vibronic contributions to their 77 K emission spectra are much stronger than expected based on comparison to the monometallic analogs (around twofold in some complexes) and this feature is characteristic of bimetallic complexes in which the mixed-valence excited states are electronically localized. The weaker excited state than ground state donor/acceptor electronic coupling in this class of complexes is attributed to PP-mediated super-exchange coupling in which the mediating orbital of the bridging ligand (PP-LUMO) is partly occupied in the MLCT excited states, but is unoccupied in the ground states; therefore, the vertical Ru(III)-PP− (MLCT) energy is larger and the mixing coefficient smaller in these excited states than is found for Ru(II)-PP in the corresponding ground states. 相似文献
113.
Chains, ladders and sheets of d metal–organic polymers generated from the flexible bipyridyl ligands
Yaqiong Gong Ruihu Wang Daqiang Yuan Weiping Su Yougui Huang Chengyang Yue Feilong Jiang Maochun Hong 《Polyhedron》2007,26(18):5309-5316
By use of the three-layer diffusion method, reactions of flexible bipyridyl ligands (4,4′-bpp or 3,3′-bpp) with M(II) salts (M = Zn, Cd) and multi-carboxylate ligands resulted in the formation of four interesting d10 metal–organic coordination polymers: [Zn(μ-4,4′-bpp)Br2]n (1), [Zn(μ-4,4′-bpp)(1,2-bdc)]n · nH2O (2), [Zn(μ-3,3′-bpp)(1,3-bdc)]n · nCH3OH · 2nH2O (3) and [Cd(μ-3,3′-bpp)(C4H2O4)]n · 3nH2O (4) (4,4′-bpp = 2,2′-bis(4-pyridylmethyleneoxy)-1,1′-biphenylene; 3,3′-bpp = 2,2 ′-bis(3-pyridylmethyleneoxy)-1,1′-biphenylene; bdc=benzenedicarboxylate, C4H4O4 = fumaric acid). Complex 1 has a 2D sheet structure consisting of two unusual zigzag Zn(II) chains which are nearly perpendicular to each other. Complex 2 is comprised of two-leg ladders, in which [Zn(4,4′-bpp)] chains serve as the side rails and 1,2-bdc ligands serve as the cross rungs. In complex 3, every two 1,3-bdc ligands connect the neighbouring Zn(II)-3,3′-bpp dimetallic rings in η1 coordination modes into an interesting chain structure. Complex 4 consists of an anionic macrocycle-containing cadmium dicarboxylate sheets that are separated by 3,3′-bpp. These d10 metal complexes exhibit high thermal stabilities and strong luminescence efficiencies. 相似文献
114.
A study of the mechanisms involved in the separation of metal ions with a mixed-bed stationary phase
Summary The optimization of chromatographic methods for the determination of metal species require an understanding of the mechanisms
involved. In this work, the separation of Cd, Co, Cu, Fe(II/III), Mn, Pb and Zn using a mixed bed column (IonPac CS5A) and
a cation-exchange column (IonPac CS2) is studied as a function of mobile phase composition. The type and concentration of
complexing agent and of ionic strength modificators were evaluated. The charge of analytes were calculated using the classical
ion exchange approach to highlight the effect of eluent composition on retention. The comparative study enabled us to identify
an optimal eluent composition for the separation of the nine metal species. 相似文献
115.
116.
热处理及与KOH共炭化对深度脱除煤中无机矿物质的促进作用 总被引:1,自引:0,他引:1
研究了煤经热处理(炭化)以及煤与KOH共炭化对酸洗脱灰的影响。结果表明,煤经炭化再用盐酸洗涤,可以在缓和的条件下大幅度提高酸洗脱灰率;煤与KOH共炭化后再酸洗,不仅对煤中的粘土、黄铁矿等无机矿物质有很好的效果,还特别适于脱除在一般情况下都难以除去的石英矿物。 相似文献
117.
Jorge Macanás 《Analytica chimica acta》2005,534(1):101-108
Activated composite membranes (ACMs) containing di-(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) as a carrier have been found to facilitate the transport and separation of several cations. This paper describes an approach to the chemical characterisation of the transport phenomena of Zn2+, Cd2+, Cu2+, Ni2+, Sn2+ and In3+ by an ACM. The selectivity of D2EHDTPA based ACM towards different metal ions is presented and discussed focusing in Zn2+ and Cd2+ transport and recovery. Selectivity demonstrates that zinc ions are removable from mixtures due to the different extraction strength of D2EHDTPA. Such selectivity is based on the differences of the dynamic behaviour of the metal ions transport. In addition, a correlation of the chemical behaviour of those ACM systems with the corresponding solvent extraction systems has been found. 相似文献
118.
CHEN Kai ZHU Zhong-liang ZHANG De-jun 《高等学校化学研究》2006,22(4):435-438
IntroductionStudies on reversible kinetic systems are consi-dered as a hotspot of chemical and biochemical kineticresearches[1,2]. Of late, some researches have been fo-cused on the simultaneous optimization of the obverseand reverse rate constants[3,4].H… 相似文献
119.
Summary. A new polymeric resin with sulfonamide pendant functions has been prepared for the selective extraction of mercuric ions.
This polystyrene sulfonamide urea resin with a 3.5 mmol/g total nitrogen content is able to selectively sorb mercury from
aqueous solutions. The mercury sorption capacity of the resin is around 1.60 mmol/g under non-buffered conditions. The experiments
performed under identical conditions with some metal ions reveal that Cd(II), Pb(II), Zn(II), and Fe(III) ions are also extractable
in low quantity (0.05–0.1 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis
of the amide groups. 相似文献
120.
Fa-Kun Zheng A-Qing Wu Yan Li Guo-Cong Guo Ming-Sheng Wang Qiang Li Jin-Shun Huang 《Journal of Molecular Structure》2005,740(1-3):147-151
Three new metal complexes, Cu(4-Hcba)2(4-cba)2(Py)2 (4-Hcba=4-cyanobenzoic acid) 1 and M[H(4-cba)2]2(Py)2 (M=Ni 2, Co 3), have been prepared by the treatment of 4-Hcba with the respective metal nitrate M(NO3)2 (M=Cu, Ni, Co) in the presence of pyridine (Py). Single-crystal X-ray diffraction analyses (3 is isostructural to 2) show that the obtained complexes are of isolated mononuclear and the metal atoms have distorted octahedral coordination environment. Two different types of intramolecular hydrogen bonds exist: asymmetrical O–HO for 1 and symmetrical OHO for 2 and 3. The crystal packing between the molecular complexes is controlled mainly by T-shaped C–Hπ interactions between pyridine and phenyl rings. Preliminary discussions on IR, UV–VIS and fluorescent spectra have also been carried out. 相似文献