in this article, theoretical studies on the selective complexation of the halide ions (f¯, cl¯ and br¯) and ion pairs (na+f¯, na+cl¯ and na+br¯) with the cyclic nano-hexapeptide (cp) composed of l-proline have been performed in the gas phase. in order to calculate the dispersion interaction energies of the cp and ions, dft-d3 calculations at the m05-2x-d3/6-31g(d) level was employed. based on t...

a simple extractive spectrophotometric method has been developed for the estimation of miconazole nitratein both pure and pharmaceutical preparation. the method is based on the formation of ion-pair complex of thedrug with acidic dye bromothymol blue (btb) in acidic condition, followed by its extraction in organic solvent(chloroform). the absorbance was measured against the corresponding blank....

Electron transfer in collisions between Rydberg atoms and targets that attach free low-energy electrons can lead to the formation of heavy-Rydberg ion-pair states comprising a positive-negative ion pair that orbit each other at large separations weakly bound by their mutual electrostatic attraction. It is shown that measurements of the velocity distribution of the ion-pair states produced in su...

A simple, accurate and fast vortex-assisted dispersive liquid-liquid microextraction procedure has been developed for the extractive spectrophotometric determination of niflumic acid in biological samples. The method is based on the formation of an ion association complex between niflumic acid and methylene blue. The resulting ion-pair was extracted into dichloromethane and its absorbance was m...

Ion-pairing is reported to improve the lipophilicity and subsequently the transport rate of polar drugs across lipid membranes. Lipophilisation of ionic drugs with high aqueous solubilities by ion-pair formation with appropriate counter-ion have proven to be promising for several applications. The aim of this review is to present the usefulness of ion-pair for improving the poor bioavailability...

Complex formation and intermolecular excited-state proton transfer (ESPT) between a dihydroxy-1,8-naphthalimide photoacid and organic bases are investigated in polar aprotic solvents. First, quantum chemical calculations are used to explore the acid-base and spectroscopic properties and to identify energetically favorable complexes. The two hydroxyl groups of the photoacid enable stepwise forma...