The excited-state proton transfer and subsequent intramolecular ion pair formation of a cupreidine-derived Cinchona organocatalyst (BnCPD) were studied in THF-water mixtures using picosecond time-resolved fluorescence together with global analysis. Full spectral and kinetic characterization of all the fluorescent species allowed us to monitor the 3-step process for the ion pair dissociation. In...

A sensitive spectrophotometric method for the determination of trace amounts of chromium(VI) is described. Chromium(VI) forms chlorochromate anion in the presence of acid and chloride ion. The formed anion is extracted in toluene as ion-pair with a cationic dye rhodamine 6G. At 535 nlll absorption maximum molar absorptivity is 2x104 I mol-I em-I. The colour is stable for 4 h and the system obey...

The global electrostatic mode in pair-ion plasmas is discussed for cylindric geometry and for a radially inhomogeneous equilibrium density. In the case of a Gaussian radial density profile, exact analytical eigen solutions are found in terms of the Kummer confluent hypergeometric functions. The mode is identified as a convective cell propagating in the poloidal and axial direction, having at th...

The free energy of the binding reaction between EcoRI restriction endonuclease and a specific cognate dodecadeoxynucleotide (d(CGCGAATTCGCG)) has contributions from both electrostatic and nonelectrostatic components. These contributions were dissected by measuring the effects of varying salt concentration on the equilibrium binding constant and applying the thermodynamic analyses of Record et a...

Nisoldipine, a 1-4-dihydropyridine drug is determined by the development of simple and sensitive Extractive Spectrophotometric method. In the present study an ion-pair complex of amino derivative of the Nisoldipine with Bromocresol Green Solution in acidic medium is formed with subsequent extraction of the ion-pair complex in Chloroform. Maximum absorption was seen at the wavelength of 418 nm t...

Complexation in symmetric solutions of oppositely charged polyelectrolytes is studied theoretically. We include polyion crosslinking due to formation of thermoreversible ionic pairs. The electrostatic free energy is calculated within the Random Phase Approximation taking into account the structure of thermoreversible polyion clusters. The degree of ion association is obtained self-consistently ...

The threshold-ion-pair-production (TIPP) spectra of H2S and D2S have been recorded in the vicinity H++SH?[X1?+(v?=0,1;J?)] D++SD?[X1?+(v?=0,1;J?)] thresholds using a tunable vacuum-ultraviolet laser cold molecular samples (Trot?20K) supersonic expansions. ion-pair-production signal was found to be much stronger at v?=0 than v?=1 thresholds. From rotational structure spectra, dominant photodisso...

The stability of the mercury ion mediated dU-HgII-dU pair depends on substituents introduced at the 5-position of the pyrimidine moiety. To this end, a series of oligonucleotides were synthesized with dU modification in central position. Common and new phosphoramidites were utilized. Hybridization experiments provided 12-mer duplexes with non-canonical "dU-dU" pairs. In most cases Hg2+ stabiliz...