Hydrothermal syntheses, crystal structures, and characteristics of a series of Cd-btx coordination polymers (btx = 1,4-Bis(triazol-1-ylmethyl)benzene)

Four novel cadmium-btx (btx = 1,4-bis(triazol-1-ylmethyl)benzene) coordination polymers [Cd(btx)(2)(NO(3))(2)](n)(1), [Cd(btx)(2)Cl(2)](n)(2), [Cd(btx)(SO(4))(H(2)O)(2)](n)(3), and [Cd(btx)(S(2)O(7))(H(2)O)](n)(4) have been prepared by hydrothermal reaction (140 or 180 degrees C) and characterized. Both 1 and 2 have two-dimensional rhombohedral grid structures, 3 possesses a two-dimensional rectangular grid structure, and 4 displays a three-dimensional framework, which is formed by btx bridging parallel layers. To the author's best knowledge, polymer 4 is the first Cd(II) polymer in which the Cd(II) ion is eight-coordinated in a hexagonal bipyrimidal geometry. In addition, we studied the effects of temperature on the hydrothermal reaction system of btx and CdSO(4) and found that different products can be obtained at different temperatures. Furthermore, polymer 3 possesses a very strong third-order NLO absorptive effect with an alpha(2) value of 1.15 x 10(-)(9) m W(-1). Polymers 2-4 display strong fluorescent emissions in the solid state at room temperature. The DTA and TGA results of the four polymers are in agreement with the crystal structures.     

The synthesis of nucleus-shell Cd(OH)<Subscript>2</Subscript>/CdS structures by chemical precipitation from aqueous solutions

The region of stable coexistence of Cd(OH)₂ and CdS as a function of pH and the concentration of the complex-forming agent (ammonia) was determined by thermodynamic analysis with the purpose of the preparation of Cd(OH)₂ cadmium hydroxide particles surrounded by cadmium sulfide CdS shells. In this region, powders were obtained by chemical precipitation during various precipitation times from aqueous solutions. X-ray diffraction was used to track the growth of the CdS nanophase of a disordered structure and hexagonal Cd(OH)₂ phase consumption with time. It was found by complexonometry that part of cadmium formed insoluble structures as a result of the formation of continuous nanosized CdS shells on single crystalline Cd(OH)₂ particles. A comparative analysis of the experimental data was used to determine the kinetics of formation of nucleus-shell Cd(OH)₂/CdS particles in the system.     

Synthesis of stable cadmium sulfide nanoparticles using surfactin produced by Bacillus amyloliquifaciens strain KSU-109

In this study, a surfactin was extracted from a novel surfactant producing bacterial strain Bacillus amyloliquifaciens KSU-109, isolated from rhizosphere of date palm (Phoenix dactylifera), and characterized based on 16Sr RNA and sfp genes using Blastn, Blastx and phylogenetic analyses. The study was performed to obtain a renewable bioresource for surfactin production, and its application in nanotechnology as a non-hazardous and environmentally compatible nanoparticle (NP) stabilizer. The strain KSU-109 produced the surfactin with an average yield of 160 mg/L with strong surfactant activity, reducing the surface tension of the medium from 72 mN/m to 29.3 mN/m. The surfactin preparation was used for synthesizing the cadmium sulfide nanoparticles (CdS-NPs) by mixing 0.005% surfactin with 1mM Cd(NO(3))(2) in 1:1 ratio (v/v) and 10mM Na(2)S solution at pH 7.2 and ambient temperature, which were stable up to 120 days. The surfactin stabilized CdS-NPs were characterized using XRD, TEM, and spectroscopic techniques. The data revealed a significant role of surfactin as a stabilizer and capping agent, which also causes phase transition to yield the cubic/hexagonal CdS-NPs of average size of 3-4 nm. The results elucidated the significance of biocompatible and biodegradable surfactin as an effective and inexpensive stabilizing agent for developing stable CdS nanoparticles.     

Preparation of CdS nanoparticles by hydrothermal method in microemulsion

CdS nanoparticles with good crystallinity were prepared by hydrothermal method in microemulsion composed of polyoxyethylene laurylether/water/cyclohexane/butanol. The structure and the size of the CdS nanoparticles were analyzed by TEM and XRD. The UV-Vis optical absorption of the samples was also investigated. The results show that hydrothermal treatment is an effective method to prepare CdS nanoparticles of hexagonal structure at lower temperature. The particles were in dimensional uniformity. The diameter of the CdS nanoparticles decreased with the increase of the molar ratio of water to surfactant. The minimum diameter of the CdS nanoparticles prepared in this work was about 10 nm. Obvious blue shift appeared in the UV-Vis absorption spectra. Translated from Chinese Journal of Inorganic Chemistry, 2006, 22(5): (in Chinese)     

不同晶型纳米CdS的合成及其光催化活性

以醋酸镉为镉源,硫脲为硫源,采用配合物热分解法,通过改变硫脲/醋酸镉的摩尔配比,合成了具有不同晶型的纳米CdS．当n（S）／n（Cd）=0．5—3时,合成的CdS相分别为立方相（n（S）／n（Cd）=0．5）,立方相和六方相的混相（n（S）／n（Cd）=1．0～1．5）,六方相（n（S）／n（Cd）≥2）．通过XRD,TEM,UV—Vis光谱,IR光谱等对CdS的相组成,形貌,粒径,吸光性能,表面结构等进行了表征．光催化降解罗丹明B的活性结果表明,不同CdS相组成的活性顺序为立方相〉六方相〉混相（立方＋六方）,其中立方CdS相由于有较强的吸附作用、光吸收性能和较小的粒径（10～13nm）,对罗丹明B具有最好的光催化降解活性．     

CdS量子点的一步法合成及量子产率

以油酸为配体,十八烯为溶剂,采用一步法合成了CdS量子点,研究了反应温度、反应时间和Cd/S的摩尔比对量子点光谱性能的影响.X射线衍射(XRD)和高分辨透射电镜(HRTEM)测试结果表明,所获得的CdS量子点为立方闪锌矿结构,且尺寸分布均一,结晶度高,其较强的带边发光、尖锐的紫外吸收峰以及狭窄的荧光发射峰进一步表明量子...     

Synthesis and characterization of poly(acrylic acid) stabilized cadmium sulfide quantum dots

Cadmium sulfide (CdS) nanoparticles (NPs) capped with poly(acrylic acid) (PAA) were prepared in aqueous solutions from Cd(NO3)2 and Na2S. Influence of the COOH/Cd ratio (0.8-12.5), reaction pH (5.5 and 7.5), and PAA molecular weight (2100 and 5100 g/mol) on the particle size, colloidal stability, and photoluminescence were investigated. A Cd/S ratio of <1 causes ineffective passivization of the surface with the carboxylate and therefore results in a red shift of the absorption band and a significant drop in photoluminescence. Therefore, the Cd/S ratio was fixed at 1.1 for all experiments studying the mentioned variables. PAA coating provided excellent colloidal stability at a COOH/Cd ratio above 1. Absorption edges of PAA-coated CdS NPs are in the range of 460-508 nm. The size of the NPs increases slightly with increasing PAA molecular weight and COOH/Cd ratio at pH 7.5. It is demonstrated that there is a critical COOH/Cd ratio (1.5-2) that maximizes the photoluminescence intensity and quantum yield (QY, 17%). Above this critical ratio, which corresponds to smaller crystal sizes (3.7-4.1 nm) for each reaction set, the quantum yield decreases and the crystal size increases. Moreover, CdS NPs prepared at pH 7.5 have significantly higher QY and absorb at lower wavelengths in comparison with those prepared at pH 5.5. Luminescence quenching has not been observed over 8 months.     

CdS纳米粒子的水热微乳法制备

0引言CdS是一种重要的Ⅱ-Ⅵ族半导体,其独特的光电化学性能引起人们的广泛关注,而其性能与晶粒尺寸、晶体结构等密切相关,因而CdS的纳米结构的研究备受关注[1￣3]。目前,制备CdS纳米粒子的主要方法有溶剂热法[4],化学浴沉积法[5],微乳液法[6]等。微乳液是合成球形纳米粒子的良好介质,具有实验装置简单,操作方便,应用领域广并且有可控制微粒的粒度等优点[7]。但其在室温条件下合成的CdS粒子的结晶性较差,严重影响其光电性能。Gan和Liu等[8]曾在NP5-NP9/PE/SOL微乳液中,在室温及水热条件下合成ZnS:Mn发光纳米材料,来提高在微乳液中制…     

Preparation, characterization, and optical, electrochemical property research of CdS/PAM nanocomposites

CdS/PAM nanocomposites have been successfully synthesized in situ via a ultrasound-assisted route under ambient condition, employing CdCl(2) and Na(2)S(2)O(3) as Cd(2+) and S(2-) ion sources and acrylamide (AM) and (NH(4))(2)S(2)O(8) as organic monomers and initiating reagents, respectively. The results from X-ray powder diffraction (XRD) analysis and the IR spectrum of the final product showed the formation of CdS nanoparticles and the polymerization of AM monomers. SEM observations showed that the CdS/PAM nanocomposites could film on the quartz substrate and some holes in which many nanorods regularly arranged distributed on the film. The UV-vis absorption and PL spectra of CdS/PAM nanocomposites obviously differed from those of CdS nanoparticles prepared under the same conditions due to the presence of PAM. The electrochemical research showed that CdS/PAM nanocomposites had a stronger ability to promote electron transfers between Hb and the Au electrode than CdS nanoparticles prepared under the same conditions. A possible formation mechanism was also suggested based on the results of experiments.     

Polymeric zinc ferrocenyl sulfonate as a molecular aspirator for the removal of toxic metal ions

A porous bilayered open coordination polymer [Zn(4,4'-bpy)(2)(FcphSO(3))(2)](n) (1; FcphSO(3)Na=m-ferrocenyl benzenesulfonate), has been assembled from Zn(NO(3))(2), m-ferrocenyl benzenesulfonate, and the bridging ligand 4,4'-bipyridine (4,4'-bpy). Ion-exchange induced products [Cd(0.6)Zn(0.4)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (2), [Zn(0.75)Pb(0.25)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (3), and [Cu(0.5)Zn(0.5)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (4) could be obtained directly by suspending a big single crystal of 1 into concentrated solutions of Cd(NO(3))(2), Pb(NO(3))(2), and Cu(NO(3))(2), respectively. Most importantly, the big single crystal of 1 could be partly regenerated after immersion into concentrated aqueous solutions of Zn(NO(3))(2). On the other hand, powdered 1 could also be used as a metal ion adsorbent because of the well-defined pore size and pore shape. Ion exchange takes place along with the process of ion sorption. The big single crystal of 1 removes harmful metal ions by means of ion exchange, whereas powdered 1 removes toxic metal ions mainly through ion sorption. Also, compound 1 could be employed as a multi-ion analysis fluorescent probe to detect dangerous metal ions, such as Pb(2+), Cd(2+), Ag(+), and Cu(2+). The compounds described in this study may have potential applications in the design of new molecular devices.     

Investigation of hydrothermal routes to mixed-metal cerium titanium oxides and metal oxidation state assignment using XANES

The reaction between TiF(3) or TiO(2) and Ce(3+) in sodium hydroxide solutions yields highly crystalline NaCeTi(2)O(6) at room temperature and under mild hydrothermal conditions (T < or = 240 degrees C). There is no evidence for the formation of ternary Ce-Ti-O materials by this method, and the use of bases other than NaOH always produces poorly crystalline materials. The material NaCeTi(2)O(6) has a distorted perovskite structure with sodium and cerium ions randomly occupying the A sites: Pnma, a = 5.4517(8) A, b = 7.7292(6) A, c =5.4573(3) A. XANES spectroscopy at the Ti K edge and Ce L(III) edge, with reference to crystalline model compounds, reveals that cerium is found solely as Ce(III) and titanium as Ti(IV) in NaCeTi(2)O(6). Isomorphous substitution of Ce(3+) by Nd(3+) or Ti(4+) by V(4+) is found to be very facile under hydrothermal conditions (at a temperature of 240 degrees C), by addition of appropriate amounts of metal salts to the hydrothermal reaction mixtures. The series NaCe(1-x)Nd(x)Ti2O6 (0 < or = x < or = 1) and NaCeTi(2-x)V(x)O6 (0 相似文献   

Shape control of monodisperse CdS nanocrystals: hexagon and pyramid

The wurtzite CdS nanocrystals with hexagonal or pyramidal geometries were selectively synthesized by tuning the molar ratio of Cd and S precursors in the solution system. For hexagonal nanocrystals, a 2-D or 3-D superlattice assembly could be obtained due to the narrow particle size distribution. The pyramidal CdS nanocrystals were divided into two geometries: the hexagon-based pyramid and the triangle-based pyramid. The realization of the pyramidal geometries further extends the shape multiformity of wurtzite CdS nanocrystals, which may bring new opportunities for the development of CdS semiconductors. The room-temperature absorption spectra of CdS nanoparticles with hexagonal and pyramidal morphologies exhibited a discrepancy in peak positions, revealing the existence of a profound shape-property relationship for the CdS nanophase.     

A Simple Approach to Fabricate CdS-SiO2 Hybrid Microspheres by Producing CdS Nanoparticles on the Surface of Thiolated SiO2 Microspheres

IntroductionSemiconductor nanoparticles show a quantum sizeeffect and have attracted much attention because oftheir unique photochemical and photophysical proper-ties[1—4].In recent years,quantumdots of CdS and in-organic nanoparticles hybrid composites …     

Hydrothermal synthesis, characterization and its photoactivity of CdS/Rectorite nanocomposites

CdS/Rectorite nanocomposites were prepared through hydrothermal method by using Cd[NH₂CSNH₂]₂Ac₂ complex as precursor of CdS which was derived from cadmium acetate and thiourea. The obtained nanocomposites were characterized by X-ray diffraction (XRD), Fourier transfer infrared spectra (FTIR), diffusion reflection spectra (DRS), transmission electron microscopy (TEM) and the selected area electron diffraction (SAED) patterns. Experimental results indicate that CdS exist in at least three forms: CdS adsorbed at surface, CdS pillared in montmorillonite-like layers of Rectorite and CdS pillared in the new layered structure formed during the hydrothermal process. Those CdS crystals are hexagonal symmetry. The photoactivity and photostability of the obtained CdS/Rectorite nanocomposites are improved significantly compared to that of the reference Rectorite and pure CdS.     

Spontaneous organization of uniform CeO2 nanoflowers by 3D oriented attachment in hot surfactant solutions monitored with an in situ electrical conductance technique

Uniform CeO(2) nanoflowers were synthesized by rapid thermolysis of (NH(4))(2)Ce(NO(3))(6) in oleic acid (OA)/oleylamine (OM), by a unique 3D oriented-attachment mechanism. CeO(2) nanoflowers with controlled shape (cubic, four-petaled, and starlike) and tunable size (10-40 nm) were obtained by adjusting the reaction conditions including solvent composition, precursor concentration, reaction temperature, and reaction time. The nanoflower growth mechanism was investigated by in situ electrical conductance measurements, transmission electron microscopy, and UV/Vis spectroscopy. The CeO(2) nanoflowers are likely formed in two major steps, that is, initial formation of ceria cluster particles capped with various ligands (e.g., OA, OM, and NO(3) (-)) via hydrolysis of (NH(4))(2)Ce(NO(3))(6) at temperatures in the range 140-220 degrees C, and subsequent spontaneous organization of the primary particles into nanoflowers by 3D oriented attachment, due to a rapid decrease in surface ligand coverage caused by sudden decomposition of the precursor at temperatures above 220 degrees C in a strong redox reaction. After calcination at 400 degrees C for 4 h the 33.8 nm CeO(2) nanoflowers have a specific surface area as large as 156 m(2) g(-1) with high porosity, and they are highly active for conversion of CO to CO(2) in the low temperature range of 200-400 degrees C. The present approach has also been extended to the preparation of other transition metal oxide (CoO, NiO, and CuO(x)) nanoflowers.     

A novel ultrasound-assisted approach to the synthesis of CdSe and CdS nanoparticles

Hexagonal CdSe and hexagonal CdS nanoparticles have been prepared using Cd(Ac)₂ and less hazardous elemental Se or S as precursors, respectively, with the aid of ultrasound irradiation under an atmosphere of H₂/Ar (5/95, V/V). The products consist of 7-10 nm nanocrystallites which aggregated in the form of polydispersive nanoclusters with sizes in the range 30-40 nm in the case of CdSe, and near monodispersive nanoclusters with a mean size of about 40 nm in the case of CdS. X-ray diffraction, high-resolution TEM and SAED patterns (selected area electron diffraction patterns) show that the as-prepared particles are well crystallized. X-ray photoelectron spectroscopy (XPS) measurements further confirm the formation of CdSe and CdS. Diffuse reflection spectra indicate that both the CdSe and the CdS nanocryslallites are direct band-gap semiconductors with band-gap values of about 1.83 and 2.62 eV, respectively. Control experiments demonstrate that the hydrogen is the reducing agent, and the extreme high temperature induced by the collapse of the bubble accelerates the reduction of elemental Se or S by hydrogen. An ultrasound assisted in situ reduction/combination mechanism is proposed.     

Utility of anhydrous neodymium nitrate as a precursor to extended organoneodymium nitrate networks

Hydrated neodymium nitrates can be readily transformed to anhydrous ether solvates which react with cyclopentadienyl reagents to make organometallic nitrate complexes with variable degrees of oligomerization. Heating Nd(NO(3))(3)(H(2)O)(6) in tetrahydrofuran at reflux, removal of solvent, drying at 100 degrees C under high vacuum, and addition of hot THF generates Nd(NO(3))(3)(THF)(3), 1. Using dimethoxyethane, Nd(NO(3))(3)(DME)(2), 2, can be obtained similarly. Addition of NaC(5)Me(5) to 1 generates (C(5)Me(5))Nd(NO(3))(3)(THF)Na(THF)(x)complexes which crystallize as ([(C(5)Me(5))(NO(3))(2)Nd(THF)(micro-NO(3))](2)Na(THF)(4))[Na(THF)(6)], 3, or [(C(5)Me(5))Nd(THF)(mu-NO(3))(3)Na(THF)(2)](n), 4, depending on the conditions. The trimetallic Nd(2)Na unit in 3 forms an extended system in 4 via bridging nitrates. Addition of KC(5)Me(5) and 18-crown-6 to 1 generates another extended complex [(C(5)Me(5))Nd(THF)(NO(3))(mu-NO(3))(2)K(18-crown-6)](n), 5, in which an 18-crown-6 ligated potassium links neodymium centers via two bridging nitrates and an agostic interaction between a C(5)Me(5) methyl group and potassium.     

Controlled nucleation and growth of CdS nanoparticles in a polymer matrix

In-situ synchrotron X-ray diffraction (XRD) was used to monitor the thermal decomposition (thermolysis) of Cd thiolates precursors embedded in a polymer matrix and the nucleation of CdS nanoparticles. A thiolate precursor/polymer solid foil was heated to 300 degrees C in the X-ray diffraction setup of beamline W1.1 at Hasylab, and the diffraction curves were each recorded at 10 degrees C. At temperatures above 240 degrees C, the precursor decomposition is complete and CdS nanoparticles grow within the polymer matrix forming a nanocomposite with interesting optical properties. The nanoparticle structural properties (size and crystal structure) depend on the annealing temperature. Transmission electron microscopy (TEM) and photoluminescence (PL) analyses were used to characterize the nanoparticles. A possible mechanism driving the structural transformation of the precursor is inferred from the diffraction features arising at the different temperatures.     

Stabilization of the thermodynamically favored polymorph of cadmium chalcogenide nanoparticles CdX (X = S, Se, Te) in the polar mesopores of SBA-15 silica

A versatile synthetic approach to cadmium chalcogenide nanoparticles in the mesopores of SBA-15 silica as a host matrix was developed. The use of cadmium organochalcogenolates of the type Cd(XPh)(2).TMEDA (X = S, Se, Te) allowed the preparation of nanoparticles of all three cadmium chalcogenides following the same experimental protocol. Particles of CdS, CdSe, and CdTe with a particle size of 7 nm were prepared from this class of single-source precursors. The incorporation of the precursor molecules into the pores was achieved by melt infiltration at a temperature of 140 degrees C. Subsequent pyrolysis of the precursors in the mesopores yielded the semiconductor particles. Owing to the high polarity of the silanol-covered pore walls, which lower the surface energy of the particles to a large extent, the dimorphic cadmium chalcogenides are obtained in their thermodynamically favored modifications; e.g., CdS particles crystallize in the wurtzite type, CdTe particles are obtained in the zinc blende structure, and CdSe (where no unambiguous preference exists) crystallizes as a "mixture" of both structures with a rather random stacking sequence.     

Silica Coating of Water-Soluble CdTe/CdS Core-Shell Nanocrystals by Microemulsion Method

"Using Te powder as a tellurium source and Na2S as a sulfur source, core-shell CdTe/CdS NPs were synthesized at 50 oC. UV-visible and photoluminescence (PL) spectra were used to probe the effect of CdS passivation on the CdTe quantum dots. As the thickness of CdS shell increases, there is a red-shift in the optical absorption spectra, as well as the PL spectra. The broadening absorption peaks and PL spectra indicate that the size distributions of CdTe/CdS NPs widen increasingly with the increase of CdS coverage. The PL spectra also show that the fluorescence intensity of CdTe QDs will increase when the particles are covered with CdS shell with ratio of S/Te less than 1.0, otherwise it will decrease if the ratio of S/Te is larger than 1.0. Furthermore, the (CdTe/CdS)@SiO2 particles were prepared using a water-in-oil microemulsion method at room temperature in which hydrolysis of tetraethyl orthosilicate leads to the formation of monodispersed silica nanospheres. The obtained (CdTe/CdS)@SiO2 particles show bright photoluminescence with their fluorescence intensity being enhanced 18.5% compared with that of CdTe NPs. TEM imaging shows that the diameter of these composite particles is 50 nm. These nanoparticles are suitable for biomarker applications since they are much smaller than cellular dimensions."