Among the polar interactions occurring in pancreatic lipase/colipase binding, only one ion pair involving lysine 400 on lipase and glutamic acid 45 on colipase has been described. These residues are strictly conserved among species, suggesting that the ion pair is likely to play an important role. Therefore, in order to prevent this interaction, mutations intended to neutralize or inverse the c...

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 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...

a simple, precise, rapid and low-cost potentiometric method for diclofenac determination in pharmaceuticals is proposed. a new diclofenac-sensitive electrode was constructed by incorporating the diclofenac ion pair complex with butyl rhodamine b into graphite matrix. the electrode exhibited a linear response over the concentration range of 1 × 10-4 – 5 × 10-2 mol l-1, a detection limit of 3.9×1...

An extractive spectrophotometric method is described for the assay of sitagliptin phosphate in bulk drug and in tablets. Sitagliptin phosphatewas extracted as an ion-pair complex from the solution containing Eriochrome black T and 0.1N HCl into chloroform and the absorbance of the complex was measured at 500nm.The working conditions of the method were investigated and optimized. Beer’s law plot...

Complexes of benzo-15-crown-5 macrocycle with Li+ and Cs+ ions were investigated by 7Li and 133Cs NMr in a number of nonoqueous solutions. The resulting 1:1 complex with Li+ ion was found to be much more stable than that with Cs+ ion. With the exception of pyridine solutions the stabilities of the complexes varied inversely w...