Band 81, Heft 8

The IUPAC-sponsored Conference on Solid State Chemistry (SSC 2008), the eighth conference in the series since 1986, was held in Bratislava, Slovakia 6-11 July 2008. The first Solid State Chemistry Conference held in Karlovy Vary, Czech Republic, was a nucleus of this series, which has grown over the years and resulted in well-established meetings organized biannually, either in Czech or Slovak Republic. The reader can find examples of feedback on this series in the back issues of Pure and Applied Chemistry ( PAC ), which comprise the papers and opinions of invited speakers of the fifth conference in this series, also IUPAC-sponsored "Solid State Chemistry 2002". SSC 2008 focused on the branches of solid-state and materials chemistry. The event attracted not only scientists but also the producers of new materials and technologies. Over 200 participants from 29 countries representing Europe, Asia, the Americas, and Africa attended the conference and presented 18 invited talks, 73 lectures, and 146 posters. The scientific program comprised the following seven sessions: - Synthesis and Characterization of Materials - Crystal, Electronic, and Magnetic Structure - Electrochemistry and Molten Salts - Chemistry of Glasses - Novel Inorganic Materials and Nanomaterials - Layered Compounds, Clathrates, and Intercalates - Deposited Films and Surface Chemistry The invited lectures together with the rigorous choice of further influential lectures, published in this special issue of PAC, cover each topic of the conference and have been an excellent base for the discussions and represent hints for future development in the field. In addition, the lecturers were given the option of submitting manuscripts of research articles, communications, or reviews based upon their lectures or posters to Chemical Papers and Central European Journal of Chemistry ( CEJC ). The papers accepted by CEJC have already appeared in Vol. 7, Number 2, June 2009. The conference was organized by the Institute of Inorganic Chemistry of the Slovak Academy of Sciences, the Faculty of Chemical and Food Technology of Slovak University of Technology, and the Faculty of Natural Sciences of Comenius University. The conference continues to provide a friendly atmosphere for the exchange of new results and ideas among groups active in different areas of solidstate and materials chemistry. The 9th Conference on Solid State Chemistry will be held in mid-September 2010 in Prague, Czech Republic. A Web page containing an online "expression of interest" form is already active: www.ssc2010.cz. We look forward to meeting the solid-state and materials chemistry community again at this conference. Milan Drábik SSC 2008 Conference Editor

In this contribution, we present a solid-state NMR approach to characterize drug-model molecules as ibuprofen, benzoic acid and lauric acid, encapsulated in MCM-41 silica and submitted to strong confinement effects. In particular, we show that by a careful choice of the solid-state NMR sequences, it is possible to efficiently characterize these highly mobile molecules and their interactions with the pore surface. Thus, we demonstrate that 13 C NMR spectroscopy is a powerful tool to characterize and even quantify entrapped and non-entrapped species by using either single-pulse excitation (SPE) or cross-polarization (CP). Whereas the standard { 1 H}- 13 C CP experiment is of poor efficiency for mobile species, we show that 13 C signal-to-noise (S/N) ratio can be significantly improved through 1 H- 13 C cross-relaxation (namely, nuclear Overhauser effect, nOe) by using a 1 H power-gated technique. The long transversal relaxation times [ T 2 ( 1 H) up to 22 ms] observed allow the set-up of J - coupling based experiments such as 2D { 1 H}- 13 C heteronuclear multiple-quantum coherence (HMQC) in order to fully characterize the encapsulated molecules. Thus, we demonstrate that the use of sequences derived from solution-state NMR such as these two latter experiments is highly efficient to characterize highly mobile organic molecules trapped in mesopores. Finally, we show that 1 H spin diffusion-based experiments can give useful informations on the proximities between trapped molecules and the silica surface.

In the dinuclear and polynuclear metal complexes exhibiting the low-spin (LS) to high-spin (HS) transition, the spin-crossover phenomenon interferes with the magnetic exchange interaction. The latter manifests itself in forming spin-multiplets, which causes a possible overlap of the band originating in different reference spin states (LL, LH, HL, and HH). A series of dinuclear Fe(III) complexes has been prepared; the iron centers are linked by a bidentate bridge (CN - , and diamagnetic metallacyanates {Fe(CN) 5 (NO)}, {Ni(CN) 4 }, {Pt(CN) 4 }, and {Ag(CN) 2 }). Magnetic measurements confirm that the spin crossover proceeds on the thermal propagation. This information has been completed also by the Mössbauer spectral (MS) data. A theoretical model has been developed that allows a simultaneous fitting of all available experimental data (magnetic susceptibility, magnetization, HS mole fraction) on a common set of parameters.

The objective of this study was to prepare and characterize hybrid films based on layered silicates with a tetracationic porphyrin dye 5,10,15,20-tetrakis( N -methylpyridinium-4-yl)porphyrin (TMPyP) intercalated in the inorganic matrix. The properties of the TMPyP cations in the materials were compared with those of other systems (solutions, colloids) characterized mainly by absorption and fluorescence spectroscopies. Linearly polarized absorption spectroscopy, X-ray diffraction (XRD), and fluorescence microscopy were used as well. Using appropriate layered silicate templates, applying the premodification of the inorganic component with hydrophobic alkylammonium surfactants and selecting an appropriate method, one can prepare the materials of broadly variable spectral properties of the dye. The spectral variation takes place while preserving the photochemical activity of TMPyP. The interpretations of spectral changes are based on the structural changes of the TMPyP molecules adsorbed on layered silicate surface related to the flattening of cationic pyridinium substituents.

A detailed discussion of the potential energy surface of bis(cyclopentadienyl)cobalt(II), cobaltocene, is given. Vibronic coupling coefficients are calculated using density functional theory (DFT). Results are in good agreement with experimental findings. On the basis of our calculation there is no second-order Jahn–Teller (JT) effect as predicted by group theory. The JT distortion can be expressed as a linear combination of all totally symmetric normal modes of the low-symmetry, minimum-energy conformation. The out-of-plane ring deformation is the most important mode. The JT distortion is analyzed by seeking the path of minimal energy of the adiabatic potential energy surface.

The latest studies on the reactivity of inorganic-polymeric networks in selected cement-based materials and the focus toward nano- and atomic levels of grafting of polymers on interfaces represent some of the success stories of materials chemistry. Recent developments are reviewed and discussed, with particular emphasis on macro-defect-free (MDF) materials. Experimental evidence of next-nearest-neighbor (NNN) interactions has led to the definition of the scope and model of Al(Fe)–O–P cross-linking under mechanochemical synthesis conditions, in a system combining the most common (Portland) cement and commercially available polyphosphates. Current approaches to synthesis of MDF materials, together with the atomic-level interpretations of both the formed functional interfaces and the adverse influence of moisture, are discussed.

The processes of refractory metal complex electroreduction in transition from chloride to chloride–fluoride and oxofluoride melts have been studied. Decrease of the stage number of process complex electroreduction to metal and the possibility of a large number of electrons transferred in a single electrochemical stage on increasing the melt basicity has been established. It was shown that decreasing the stage number of electrode processes can be achieved by the change in anion composition (the first coordination sphere) and, in a number of cases, by the change in the cation composition (the second coordination sphere). With the melt basicity increase, a transition from reversible processes of the complex to metal discharge irreversible ones is observed, as a rule. The knowledge of electrode and chemical reactions accompanying the electroreduction of refractory metals and the study of the processes of alloy formation allow us to obtain novel niobium compounds and functional materials.

Commercial nanocrystalline titania (titanium dioxide, TiO 2 ) has been used to make TiO 2 films, which were employed to photodegrade several organic substances under photocatalytic (PC) or photoelectrochemical (PEC) operation. Hydrogen was produced during both operations while electricity was additionally produced during the PEC operation. Both processes were studied as typical examples of the current trend in the effort to produce useful forms of energy by photodegradation of organic waste materials.

Aerosol-generated mesoporous organosilica submicronic spheres have been converted into porous silicon oxycarbide (SiCO) glasses by pyrolysis at 1000 °C in an inert atmosphere. Spherical mesoporous particles obtained from acidic solutions of 1,2-bis(triethoxysilyl)ethane and Pluronic® F127 structuring agent were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption/desorption, and multinuclear solid-state magic-angle spinning (MAS) NMR. These particles were then pyrolyzed at 1000 °C and transformed into a SiCO phase as evidenced by 29 Si MAS NMR, while TEM shows preserved mesoporosity, unfortunately difficult to access owing to the presence of an outer layer of dense silica.

Microwave-hydrothermal treatment (MWHT), a modification of conventional hydrothermal treatment, has been used during post-treatment of different layered double hydroxides (LDHs). In some cases, microwaves (MWs) have been used simultaneously with urea hydrolysis or for reconstruction of the LDH structure. The main advantages of replacing the conventional furnaces by MW ovens are a noticeable reduction in the time required to complete the process to obtain well-crystallized materials, and modification of their particle size distribution and textural and thermal properties. MW radiation leads to an increase in the rate of urea hydrolysis and consequently to fast precipitation of LDHs. Finally, the memory effect of Ni,Al-based LDHs is also improved.

This article provides a brief review of theoretical and methodological concepts in the area of the charge-transfer processes at the interface between a hydrophobic ionic liquid (IL) and an electrolyte solution in water (W). Electrochemical methods of study of the W|IL interfaces are described, current experimental problems are indicated, and the most important experimental results are summarized. The relevance of electrochemistry at the W|IL interfaces to the extraction behavior of ILs is outlined.

Nanostructured materials are extensively investigated for application in energy storage and power generation devices. This paper deals with the synthesis and characterization of nanomaterials based on oxides of vanadium and with their application as electrode materials for energy storage systems viz. supercapacitors. These nano-oxides have been synthesized using a hydrothermal route in the presence of templates: 1-hexadecylamine, Tweens and Brij types. Using templates during synthesis enables tailoring of the particle morphology and physical characteristics of synthesized powders. Broad X-ray diffraction peaks show the formation of nanoparticles, confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations. SEM studies show that a large range of nanostructures such as needles, fibers, particles, etc. can be synthesized. These particles have varying surface areas and electrical conductivity. Enhancement of surface area as much as seven times relative to surface areas of starting parent materials has been observed. These properties make such materials ideal candidates for application as electrode materials in supercapacitors. Assembly and characterization of supercapacitors based on electrodes containing these active nano-oxides are discussed. Specific capacitance of >100 F g –1 has been observed. The specific capacitance decreases with cycling: causes of this phenomenon are presented.

The reduction of structural Fe in smectite may be mediated either abiotically by reaction with chemical reducing agents or biotically by reaction with various bacterial species. The effects of abiotic reduction on clay surface chemistry are much better known than the effects of biotic reduction, and differences between them are still in need of investigation. The purpose of the present study was to compare the effects of dithionite (abiotic) and bacteria (biotic) reduction of structural Fe in nontronite on the clay structure as observed by variable-temperature Mössbauer spectroscopy. Biotic reduction was accomplished by incubating Na-saturated Garfield nontronite (sample API 33a) with Shewanella oneidensis strain MR-1 (Fe II /total Fe achieved was ~17 %). Partial abiotic reduction (Fe II /total Fe ~23 %) was achieved using pH-buffered sodium dithionite. The nontronite was also reduced abiotically to Fe II /total Fe ~96 %. Parallel samples were reoxidized by bubbling O 2 gas through the reduced suspensions at room temperature prior to Mössbauer analysis at 77 and 4 K. At 77 K, the reduction treatments all gave spectra composed of doublets for structural Fe II and Fe III in the nontronite. The spectra for reoxidized samples were largely restored to that of the unaltered sample, except for the sample reduced to 96 %. At 4 K, the spectrum for the 96 % reduced sample was highly complex and clearly reflected magnetic order in the sample. When partially reduced, the spectrum also exhibited magnetic order, but the features were completely different depending on whether reduced biotically or abiotically. The biotically reduced sample appeared to contain distinctly separate domains of Fe II and Fe III within the structure, whereas partial abiotic reduction produced a spectrum representative of Fe II –Fe III pairs as the dominant domain type. The 4 K spectra of the partially reduced, fully reoxidized samples were virtually the same as at 77 K, whereas reoxidation of the 96 % reduced sample produced a spectrum consisting of a magnetically ordered sextet with a minor contribution from a Fe II doublet, indicating significant structural alterations compared to the unaltered sample.

In this paper, we present solvothermal methods to chemically synthesize Sb 2 Se 3 nanorods using dialkyl diselenophosphate (dsep) complexes of antimony. Energy-dispersive X-ray analysis shows the products are phase pure. We have also studied the Raman and photoluminescence spectroscopy of a single Sb 2 Se 3 nanorod with an average size of 60 nm in diameter and a length less than 1 μm. Techniques have been devised to immobilize and allocate a single nano-object on an electron beam (E-beam) patterned smart substrate with metallic coordination markers. This also overcomes the limitation of spatial resolution of conventional optical techniques (~1 μm) to perform optical spectroscopy on an individual nano-object less than 100 nm in size. Raman spectroscopy reveals that Sb 2 Se 3 nanorods synthesized at a lower temperature contain a small amount of Sb 2 Se 3 . The broad linewidth observed in luminescence spectra from a single rod is attributed to the increasing number of surface defects, impurities, and dangle bonds attached on the surface as the nanoparticle size reduced to nanometer scale.

The development of thin films, in the context of ongoing reduction in the size of electronic systems, poses challenging questions for the materials sciences of multifunctional nanostructures. These include the limits of size reduction, integration of heterogeneous functions, and system characterization or process control at an atomic scale. We present here different studies devoted to perovskite oxide materials (or materials with derived structure), where in specific directions of the crystal structure the atomic organization decreases down to a few nanometers, thus building nanostructures. In these materials, very original physical phenomena are observed in multilayers or superlattices, nanowires (NWs) or nanodots, mainly because strain, surfaces, and interfaces play here a predominant role and can tune the physical properties. Metal-organic chemical vapor deposition (MOCVD) routes have been used for the synthesis of oxide materials. We first introduce the basic rules governing the choice of metal-organic precursors for the MOCVD reaction. Next we discuss the principles of the pulsed injection MOCVD system. A laser-assisted MOCVD system, designed to the direct growth of 2D and 3D photonic structures, will also be described. Selected case studies will finally be presented, illustrating the powerful development of different oxide nanostructures based on dielectric, ferroelectric, or superconducting oxides, manganites, and nickelates, as well as first results related to the growth of ZnO NWs.

Errata: Atomic weights of the elements: Review 2000 (IUPAC Technical Report). (J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S.Peiser, K. J. R. Rosman, and P. D. P. Taylor). Pure Appl. Chem. 75 ,683–800 (2003); doi:10.1351/pac200375060683.