Micro‐ and Mesoporous Materials: On the way to Applications

Recent developments in the field of microporous and mesoporous materials show the potential for applications in the area of environment protection, renewable energy exploitation, and health care.     

On the way to phosphino-phosphaalkynes

By irradiation at 254 nm, the phosphino-phospholenyl-diazo compound 1 is transformed into the phospholenyl-phosphaalkene 5 while thermolysis of the phosphino-phosphiranyl-diazo derivative 2 leads to the triphosphinodiazaphosphole 6a. The transient formation of the phosphino-phosphaalkyne G1 in the latter reaction was proved by trapping with trimethylsilyldiazomethane. Similarly, the lithium salts of the silyl- and phosphino-diazomethane react with a 1σ⁴,2σ²,3σ⁴-triphosphenium salt to give the corresponding 1,2,4-diazaphospholes 6c,d, probably via the corresponding phosphaalkynes.     

On the way to formal accreditation

The Radiochemical Laboratory participated in the Technical Co-operation (TC) Project on Quality Control and Quality Assurance for Nuclear Analytical Techniques RER/2/004 organized by the International Atomic Energy Agency (IAEA) during the period June 1999 and September 2001. Motivations, major goals of participation in the project, milestones of implementation of the project, establishing the quality system, improvements fulfilling both technical and management requirements as well as major achievements for future activities of the laboratory with respect to technical and financial conditions are discussed in detail.     

On the way to high-conductivity single lithium-ion conductors

Solid electrolytes can potentially address three key limitations of the organic electrolytes used in today’s lithium-ion batteries, namely, their flammability, limited electrochemical stability and low cationic transference number. The pioneering works of Wright and Armand, suggesting the use of solid poly(ethylene oxide)-based polymer electrolytes (PE) for lithium batteries, paved the way to the development of solid-state batteries based on PEs. Yet, low cationic mobility–low Li⁺ transference number in polymer materials coupled with sufficiently high room-temperature conductivity remains inaccessible. The current strategies employed for the production of single-ion polymer conductors include designing new lithium salts, bonding of anions with the main polyether chain or incorporating them into the side chains of comb-branched polymers, plasticizing, adding inorganic fillers and anion receptors. Glass and crystalline superionic solids are classical single-ion-conducting electrolytes. However, because of grain boundaries and poor electrode/electrolyte interfacial contacts, achieving electrochemical performance in solid-state batteries comprising polycrystalline inorganic electrolytes, comparable to the existing batteries with liquid electrolytes, is particularly challenging. Quasi-elastic polymer-in-ceramic electrolytes provide good alternatives to the traditional lithium-ion-battery electrolytes and are believed to be the subject of extensive current research. This review provides an account of the advances over the past decade in the development of single-ion-conducting electrolytes and offers some directions and references that may be useful for further investigations.     

On the way to polar achiral liquid crystals

A brief review is presented of theoretical predictions and experimental observations concerning polar (pyroelectric, ferroelectric and antiferroelectric) achiral mesomorphic phases.     

Dispirocycles: Platforms for the Construction of High-Performance Host Materials for Phosphorescent Organic Light-Emitting Diodes

Spirocyclic compounds such as 9,9′-spirobifluorene (SBF) are becoming more and more attractive for use as host materials in organic optoelectronic devices. Herein, two dispirocycles, namely, dispiro[fluorene-9,9′-anthracene-10′,9′′-fluorene] and 10,10′′-diphenyl-10H,10′′H-dispiro[acridine-9,9′-anthracene-10′,9′′-acridine], were used for the construction of host materials 1 – 4 . The attached triphenylamino group determines the thermal, photophysical, electrochemical, and charge-transport properties, and therefore they have different electroluminescent performances. The device based on dispiro[fluorene-9,9′-anthracene-10′,9′′-fluorene] ( 2 ) and 10,10′′-diphenyl-10H,10′′H-dispiro[acridine-9,9′-anthracene-10′,9′′-acridine] ( 3 ) molecular platforms exhibited external quantum efficiencies of greater than 21 % with a very high power efficiency (≈100 lm W⁻¹). These results demonstrate the potential of extending the application of dispirocyclic molecular platforms with inherent rigidity for developing highly efficient host materials for organic light-emitting diodes.     

On the way to understand antioxidants: chromanol and dimethoxyphenols gas-phase acidities

Some antioxidant mechanisms displayed by several phenolic compounds relate with OH bond dissociation energy. One way for its determination, in the gas-phase, relies on acidity measurements. Gas-phase acidities were determined experimentally, applying the kinetic method, for chromanol and four dimethoxyphenols, and theoretically through quantum chemical DFT calculations for chromanol, six dimethoxyphenols and 3,4,5-trimethoxyphenol. The experimental acidity order, 2,3-dimethoxyphenol > 3,5-dimethoxyphenol > 2,6-dimethoxyphenol > 3,4-dimethoxyphenol ≈ phenol > chromanol shows good agreement with the theoretical acidity order, 2,5-dimethoxyphenol > 2,3-dimethoxyphenol > 3,4,5-trimethoxyphenol > 3,5-dimethoxyphenol ≈ 2,4-dimethoxyphenol > 2,6-dimethoxyphenol > 3,4-dimethoxyphenol > phenol > chromanol. These acidity trends were rationalized in terms of the substituent effects on the thermodynamic stabilities both of the parent phenols and the corresponding phenoxide ions. DFT calculations also evidenced the occurrence of intramolecular C-H···O hydrogen bonds whenever there are vicinal substituents (either OH, O(-) or OCH(3)) which induce further stabilization of the geometries.     

On the way to unsymmetrical terpyridines carrying carboxylic acids

For the first time arv unsymmetrical 2,2′‐6′2″‐terpyridine carry two carboxylic acids has been prepared using Hantzsch's method for pyridine ring formation and furan as a latent carboxylic group.     

On the role of reachability and observability in NMR experimentation

It is shown that the system theoretic concepts of reachability and observability are relevant to the analysis of NMR experiments. Moreover, the sets of reachable states are examined and Lie theoretic criteria are given for the reachability of the system. The question is investigated how the set of reachable states depends on the class of input functions that are allowed. Both one‐dimensional and multi‐dimensional NMR experiments are considered. This revised version was published online in July 2006 with corrections to the Cover Date.     

Self-Healing Polymeric Materials: On a Winding Road to Success

<正>Self-healing represents a next-generation technology in response to the common demands of polymeric materials for long-term stability and durability. It mimics the capability of naturally occurring species like living organisms to autonomously recover nonfatal harm. The damages inevitably generated during fabrication and service are allowed to be unconsciously repaired on a microscopic scale,     

On the way to raising the technology readiness level of diamond electrolysis

During the last decades, hundreds of scientific papers have focused on the use of anodes consisting of conductive diamond coatings, pointing out their outstanding capacity for the mineralization of organic pollutants contained in wastewater. Most of the works consist of the evaluation of the removal of different types of organics, with concentrations ranging from a few micrograms up to several grams per liter, in different matrices, from synthetic solutions containing large concentrations of sulfate or chloride to real wastewater. However, the technology readiness level has been stagnant in the lab at levels 4–5 and, because of the promising results published, there is a need to raise the readiness levels to values that indicate the full-scale applicability. In this review, two of the main challenges that need to be overcome to reach higher readiness levels are reviewed. The first is the improvement in the formulation of the doped diamond coatings targeting to be tailored for dedicated applications. Its significance is explained in terms of the high influence of these anodic surfaces on the efficiencies of the degradation of complex anthropogenic organics and, overall, on the efficient production of oxidants, that extend the oxidation of pollutants from the nearness of the anode surface to the bulk of the wastewater during electrolysis. The second advantage is the improvement in the design of the electrochemical cell that integrates the diamond anode, trying to take advantage of the outstanding properties of the diamond not only by improving the mass transport rates but also by optimizing the combination of its very efficient oxidation paths with other non-electrochemical oxidation mechanisms.     

Computational NMR of natural products: On the way to super large molecules exemplified with alasmontamine A

¹H and ¹³C nuclear magnetic resonance (NMR) chemical shifts of a tetrakis monoterpene indole alkaloid alasmontamine A with a molecular formula of C₈₄H₉₁N₈O₁₂ have been calculated at the PBE0/pcSseg-2//pcseg-2 level of theory on M06-2X/aug-cc-pVDZ geometry. In the course of the preliminary conformational search, six true minimum energy conformers were identified that can contribute to the actual conformation of this huge alkaloid. Calculated chemical shifts generally demonstrated a good agreement with available experimental data characterized with a corrected mean absolute error of 0.10 ppm for the range of about 7 ppm for protons and 1.1 ppm for the range of about 160 ppm for carbons.     

On the way to chiral epoxidations with methyltrioxorhenium(VII) derived catalysts

Methyltrioxorhenium(VII) (MTO) is successfully applied as chiral epoxidation catalysts in the presence of H₂O₂ as oxidizing agent and excess chiral Lewis base ligands derived from pyrazole. Moderate enantiomeric excesses up to ca. 30% can be reached at low reaction temperatures (−30 °C), the conversions however, being quite low (<25%). The reason for this may be the fluctionality of the N-base ligand. Glycolate complexes of MTO, applied under the same conditions reach somewhat higher enantiomeric excesses (up to ca. 40%), however, again associated with low conversions (<30%). In this case the sensitivity of the catalyst to water induced ligand removal as well as to ligand exchange with other diols is the most likely reason. Nevertheless, the enantiomeric excesses reported here are among the best observed for MTO derived catalytic systems reported to date and more active and selective systems seem feasible.     

Detection of heavy metals in water by fluorescence spectroscopy: On the way to a suitable sensor system

In order to develop a fiber optical heavy metal ion detection system, the applicability of selected complexing agents with fluorescent properties has been studied. Beginning with the application of known chelators, like BTC-5N, Newport Green™, neocuproine, and chromotropic acid, a sensor configuration has been found, which allows the detection of Cd²⁺, Ni²⁺, and Cu²⁺ well below the chemical parameter threshold values of the new Water Quality Directive 98/83/EU. The sensor itself uses a membrane separation of the chelator flow from the sample volume. The diffusion across the membrane limits the response time to about 15 to 20 min. Applications are seen in monitoring networks. Received: 6 January 2000 / Revised: 16 February 2000 / Accepted: 20 February 2000     

有机电致磷光材料的分子设计：从主体材料到客体材料

有机电致磷光器件的设计和利用，可以突破由三线态激子跃迁自旋禁阻引起的有机电致荧光器件量子效率的限制。本文综述了有机电致磷光器件和材料的研究进展，主要介绍了主体材料和客体材料的研究现状，特别是蓝光磷光器件主客体材料的研究情况。     

The European way to go: Virtual Central Laboratory

In clinical pharmaceutical trials often one central laboratory is used for the analysis of routine parameters, the so-called safety parameters. In many countries the heads of laboratory departments question the quality of such analysis in terms of quality of samples after transport, continuity of patient related medical laboratory information before, during and after the trial; turn around time; alerting procedures and consultancy to requesting physicians. On the other hand, the pharmaceutical industry prefers to work with central laboratories since they can claim certification or accreditation. Also the use of one set of reference values is an important issue, as well as electronic data transfer to the trial organizer's database. The concept of a Virtual Central Laboratory (VCL), initiated in the Netherlands, tries to solve this conflicting situation. In the concept, local hospital laboratories receive computer-assisted aid in the identification of patients, trials, visits and requests. The laboratory data are transformed using calibrator sets to produce a homogeneous data set across laboratories, resulting in one set of reference values. The data are electronically transferred to a central computer from which they are send in any desired format to the trial organizer's database. Participating laboratories are obliged to work towards accreditation. The VCL acts as a central counterpart for both the pharmaceutical industry and local laboratories. The concept offers advantages to the pharmaceutical industry, the investigator and local laboratories.