The dynamics of a moderately exergonic photoinduced charge separation has been investigated by ultrafast time-resolved infrared absorption with the dimethylanthracene/phthalonitrile donor/acceptor pair in solvents covering a broad range of polarity. A distinct spectral signature of an exciplex could be identified in the -C≡N stretching region. On the basis of quantum chemistry calculations, the...

The centrally important role of acids in aqueous chemistry has stimulated the search for the smallest droplet of hydrochloric acid. Based on several independent quantum calculations, this appears to be the HCl(H2O)4 cluster, which dissociates into the so-called solvent ion pair (SIP), H3O(+)(H2O)3Cl(-). Experimental verification of this prediction via infra-red spectroscopy is a major challenge...

Methods for separation of ions by ion-exchange, ion-pair, and zwitterion ion chromatography share at least one common thread--the induced formation of a cation-anion pair in the stationary phase. Selectivity can be defined as the relative ability of sample ions to form such a pair. Examples are given in anion-exchange chromatography to show the effect of variations in the geometry, bulkiness an...

External magnetic fields can impact recombination yields of photoinduced electron transfer reactions by affecting the spin dynamics in transient, spin-correlated radical pair intermediates. For exciplex-forming donor-acceptor systems, this magnetic field effect (MFE) can be investigated sensitively by studying the delayed recombination fluorescence. Here, we investigate the effect of preferenti...

a conductance study of the interaction between cs+, rb+, nh4+, k+, t1+ and ag+ ions and18-crown-6 (18c6), benzo-18-crown-6 (b18c6), dicyclohexyl-18-crown-6 (dc18c6),dicyclohexyl-24-crown-8 (dc24c8), dibenzo-24-crown-8 (db24c8) in different binarymixtures of acetonitrile (an) with dimethylsulfoxide (dmso) and dimethylformamide (dmf)at 25 °c has been carried out. formation constants of the result...

The D3h symmetric tris(dialkylamino)trioxatriangulenium ((R2N)3TOTA+) ions are structurally related to classical stains and fluorophores such as triphenylmethane dyes and rhodamines. New derivatives of (R2N)3TOTA+, in which long flexible alkyl chains surround the planar and rigid aromatic core, have been synthesized and isolated as hexafluorophosphate salts. In contrast to short-chain derivativ...

The purpose of the work presented here was to evaluate the influence of solution composition and analyte characteristics on responsiveness to analysis with negative ion electrospray ionization mass spectrometry. The responses of a series of structurally diverse acidic molecules were compared in various solvents. Response was generally observed to be higher in methanol than acetonitrile and resp...

A simple reversed flow injection system with minimal consumption of organic solvent has been developed for the spectrophotometric determination of anionic surfactant (AS) in water samples. The method is based on the ion-pair formation between anionic surfactant and Methylene Blue (MB) and its extraction to chloroform. Sodium dodecyl sulfate (SDS) is used as a model anionic surfactant. The sampl...

We present an analysis of the electrostatic properties in the catalytic site of papain (EC 3.4.22.2), an archetype enzyme of the C1 cysteine proteinase family, and we investigate their possible role in the formation, stabilization and regulation of the Cys25((-))...His159((+)) catalytic ion pair. The electrostatic properties were computed using a reassociation method based in multicentered mult...