Vibrational spectroscopic study of the interaction of metal ions with diethyl phosphate, a model for biological systems

Abstract

JANUSZ STANGRET and RODRIGUE SAVOIE. Can. J. Chem. 70, 2875Chem. 70, (1992. We have studied, using Raman and infrared spectroscopy, the interaction of various monovalent, divalent, and trivalent metal cations with the PO, group of diethyl phosphate in aqueous solution, at meta1:phosphate ratios ranging from 1 :40 to 6 : 1. The results show that the metal cations interact with the phosphate groups in various ways and to different extents. Spectral characteristics for some specific types of interactions are presented, namely, for direct metal binding by one of the oxygen atoms in the PO; group, the formation of water-separated ion pairs, and non-specific electrostatic interactions.JANUSZ STANGRET et RODRIGUE SAVOIE. Can. J. Chem. 70, 2875 (1 992). Nous avons etudii par spectroscopie Raman et infrarouge l'interaction de divers cations mttalliques monovalents, divalents et trivalents avec le groupe charge PO, du phosphate de diethyle en solution aqueuse, a des rapports metal : phosphate variant de 1 : 40 5 6 : 1. Les resultats demontrent que les ions se distinguent tant par leur affinite pour le groupement phosphate que par leur f a~o n d'interagir avec celui-ci. On prtsente diverses caracttristiques spectrales permettant d'identifier certains types d'interaction, notamment la fixation directe par l'un des atomes d'oxygkne du groupement phosphate, la formation de paires d'ions stparees par molCcules d'eau et les interactions non specifiques de nature electrostatique.

Computational study of dimethyl phosphate anion and its complexes with water, magnesium, and calcium

“…The strength of this shift correlates with the MOO(a) distance and the type of binding mode. Experimentally, such a shift in the ssPAO vibration was observed for samples of diethyl phosphate containing Ca 2ϩ ions, but not for those with Ni 2ϩ ions [13]. In the present study, the theoretical calculations predicted a similar effect for the inner-sphere complexes of Ca 2ϩ and Mg 2ϩ .…”

“…It has been observed that the presence of Ni 2ϩ and Ca 2ϩ leads to slight red shifts in the frequencies of diethyl phosphate [13]. Another noteworthy observation stemming from these experimental data is that the intensity of these peaks increases, becoming larger than that attributable to the ssPAO vibration.…”

“…It has been shown that the presence of various metal cations (e.g., K ) as well as hydrogen ions leads to a shift in this band to higher frequencies [13]. A correlation of the magnitude of this shift with peak intensity was observed with the more strongly affected spectra at lower intensities.…”

“…Experimental data obtained for metal-diethyl phosphate systems suggest that the presence of metal cations induces shifts of the most intense PO 2 Ϫ stretches observed in both infrared (IR) and Raman spectra [13]. However, different metal cations exhibit different-sometimes even opposite-effects on the frequencies and intensities, and a general relationship of the strength of interactions and the binding mode on spectral data has not yet been determined.…”

Interactions of Cyclic AMP and Its Dibutyryl Analogue with a Lipid Layer in the Aqueous Mixtures of Monoolein Preparation and Dioleoyl Phosphatidylcholine as Probed by X-Ray Diffraction and Raman Spectroscopy

“…By contrast, indications are that the shift of cAMP's ν s (PO 2 − ) mode in the H II phase of aqueous MO/DOPC mixture (see Table I) is related to the electrostatic interaction. For example, the studies of dialkylphosphates have demonstrated a decrease of the ν s (PO 2 − ) mode frequency upon formation of the PO 2 − • • •HOH hydrogen bond [19,20], and the effect becomes even more pronounced (further 3-5-cm −1 downshift) by the additional interaction with cations [21].…”