Crown ethers: sensors for ions and molecular scaffolds for materials and biological models.

Conducting polymers in chemical sensors and arrays

Åbo Akademi University, Process Chemistry Centre, c/o Laboratory of Analytical Chemistry, Biskopsgatan 8, FI-20500 Turku-Åbo, Finland; Faculty of Material Science and Ceramics, AGH-University of Science and Technology, Al. Mickiewicza 30, PL-30059 Cracow, Poland; and Åbo Akademi University, Process Chemistry Centre, c/o Center for Process Analytical Chemistry and Sensor Technology (ProSens), Biskopsgatan 8, FI-20500 Turku-Åbo, Finland

Potentiometric Ion Sensors

Conducting polymers, i.e., electroactive conjugated polymers, are useful both as ion-to-electron transducers and as sensing membranes in solid-state ion-selective electrodes. Recent achievements over the last few years have resulted in significant improvements of the analytical performance of solid-contact ion-selective electrodes (solid-contact ISEs) based on conducting polymers as ion-to-electron transducer combined with polymeric ion-selective membranes. A significant amount of research has also been devoted to solid-state ISEs based on conducting polymers as the sensing membrane. This review gives a brief summary of the progress in the area in recent years.

Conducting Polymer‐Based Solid‐State Ion‐Selective Electrodes

Solvent extraction of cesium ions from aqueous solution to hydrophobic ionic liquids without the introduction of an organophilic anion in the aqueous phase was demonstrated using calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) as an extractant. The selectivity of this extraction process toward cesium ions and the use of a sacrificial cation exchanger (NaBPh4) to control loss of imidazolium cation to the aqueous solutions by ion exchange have been investigated.

Extraction of cesium ions from aqueous solutions using calix[4]arene-bis(tert-octylbenzo-crown-6) in ionic liquids

Aromatic–aromatic, π–π, and cation–π interactions can be exploited in the preparation of molecular complexes between benzene-substituted crown ethers and pyridium cations. These complexes have been studied in the gas phase, in solution, and in the solid state; the structure of one of the complexes is depicted on the right.

X-ray and NMR Studies on Host–Guest Inclusion Complex Formation between Crown Ethers and Pyridinium Compounds

Oxidation and degradation of native wheat starch by acidic bromate in water at room temperature.

The effect of water and NaOH was studied on the hydrogenation of 2-ethylanthraquinone (eAQ) over alumina supported 2% Pd/Al2O3-A and 12% Pd/Al2O3-B catalysts The hydrogenation was performed in a fixed-bed reactor by circulating the eAQ solution (the concentration of eAQ was 60 g/dm3) at 50 °C and 5 bar hydrogen pressure The egg-shell catalysts were prepared by the precipitation of palladium hydroxide onto the support A (activated alumina, preimpregnated with NaH2PO4) or support B (alumina containing 10% SiO2, and preimpregnated with Na2SiO3) Prior to the hydrogenation, the catalysts were dried and pre-treated with water vapour or NaOH solution The effect of water and NaOH on the amount of active quinones (eAQ and 2-ethyl-5,6,7,8-tetrahydroanthraquinone, H4eAQ) and in particular the role of such reagents in the consumption of aromatic hydroquinone eAQH2, the primary product of the quinone system of eAQ reduction was examined The saturation of the phenyl rings in eAQH2 produces H4eAQH2, which is a reactive compound and the hydrogenolysis of the C−O bond in the tautomerized eAQH2 leads to other degradation products Water and NaOH influence the hydrogenation of C O and the hydrogenolysis of C−O bond but have no effect on the hydrogenation of the aromatic rings The increase in activity in the former C O to C−OH reduction did not depend of alumina A and B as well as the type of reagent (NaH2PO4 or Na2SiO3) introduced to alumina during the catalyst preparation These reagents however, influenced the course of degradation processes Water when introduced to the catalyst exhibited unprofitable effect on maintenance the activity of catalyst during the hydrogenation run Such an unprofitable role is related to influence of water on the course of reactions yielding degradation products

2-Ethylanthraquinone hydrogenation on Pd/Al2O3 The effect of water and NaOH on the degradation process

Synthesis, characterization, reactivity and theoretical studies of ruthenium carbonyl complexes containing ortho -substituted triphenyl phosphanes

Complexation of six aromatic, nitrogen-containing cations with various crown ethers has been studied using
 1H NMR, mass spectrometric and crystallographic methods. Hydrogen bonding appears to be the most important interaction in complexation,
 but minor effects such as π-stacking or cation–π interactions have also been observed. The stability constants of five different imidazolium perchlorate
·crown ether complexes and five other similar cation·DB18C6 complexes were determined by 1H NMR titration in acetonitrile solution. The stability of these complexes in solution
 and in the gas phase is discussed. The crystal structures of seven complexes were determined in order to study
 complexation in the solid state. Four of these are imidazolium complexes with
 different
 crown ethers
 and three are complexes
 of dibenzo-18-crown-6 with similar planar cations.

Jouni Pursiainen

Papers

X-ray and NMR Studies on Host–Guest Inclusion Complex Formation between Crown Ethers and Pyridinium Compounds

Oxidation and degradation of native wheat starch by acidic bromate in water at room temperature.

2-Ethylanthraquinone hydrogenation on Pd/Al2O3 The effect of water and NaOH on the degradation process

Synthesis, characterization, reactivity and theoretical studies of ruthenium carbonyl complexes containing ortho -substituted triphenyl phosphanes

Complexation of planar, organic, five-membered cations with crown ethers