Vibrational spectra of MgKH(XO)·15HO (X=P, As) containing dimer units [H(XO)].

Infrared and Raman spectra of MgKH(PO)·15HO and MgKH(AsO)·15HO and a series of their partially deuterated analogues were recorded and analyzed. Compounds of the type MgKH(XO)·15HO (X=P, As) are little-known and a rare case of phosphate and arsenate salts containing dimer units [H(XO)] in the crystal structure. The analysis of their IR spectra (recorded at room and liquid nitrogen temperature) and Raman spectra showed that the spectral characteristics of the XO groups connected in a dimer through a proton are not consistent with the presence of X-O-H covalent linkage and C crystallographic symmetry of the XO groups.

Infrared and Raman Spectra of Magnesium Ammonium Phosphate Hexahydrate (Struvite) and its Isomorphous Analogues. VIII. Spectra of Protiated and Partially Deuterated Magnesium Rubidium Phosphate Hexahydrate and Magnesium Thallium Phosphate Hexahydrate.

The infrared and Raman spectra of magnesium rubidium phosphate hexahydrate MgRbPO4 • 6H2O and magnesium thallium phosphate hexahydrate, MgTlPO4 • 6H2O were recorded at room temperature (RT) and the boiling temperature of liquid nitrogen (LNT). To facilitate their analysis, also recorded were the spectra of partially deuterated analogues with varying content of deuterium. The effects of deuteration and those of lowering the temperature were the basis of the conclusions drawn regarding the origin of the observed bands which were assigned to vibrations which are predominantly localized in the water molecules (four crystallographically different types of such molecules exist in the structures) and those with PO43- character.

Quantum chemical study of p-toluenesulfonic acid, p-toluenesulfonate anion and the water-p-toluenesulfonic acid complex. Comparison with experimental spectroscopic data.

The 1:1 p-toluenesulfonic acid-water complex, p-toluenesulfonic acid itself and the p-toluenesulfonate anion were studied at HF and B3LYP/6-31+G(d,p) levels of theory. Full geometry optimizations of the aforementioned species reveal non-existence of ionic minima on the explored 1:1 p-toluenesulfonic acid-water complex potential-energy hypersurfaces (PEHSs), implying that two or three p-toluenesulfonate ions (+crystal field) are required to stabilize the ionic H(3)O(+)⋯C(6)H(4)(CH(3))SO(3)(-) species found in the crystal structure of p-toluenesulfonic acid monohydrate (in fact, oxonium p-toluenesulfonate). Harmonic vibrational analyses of the p-toluenesulfonic acid-water complex as well as of the p-toluenesulfonate anion were used to confirm some of our previous reassignments of bands in the vibrational spectra of p-toluenesulfonic acid monohydrate and several metal p-toluenesulfonates.

Determination of the composition of sialoliths composed of carbonate apatite and albumin using artificial neural networks.

The determination of the components of the sialoliths is important both from the point of view of chances for a successful medical treatment of the patients and because the prevention of further re-occurrence of sialolithiasis depends upon the knowledge of the nature of the constituents of the concrements. Despite the fact that infrared spectroscopy is widely used for the determination of the composition of sialoliths, urinary calculi and bladder stones, we found no data for any chemometric method developed for such purposes. Here, a method is presented for quantitative determination of the content of salivary calculi composed of albumin and carbonate apatite (one of the most often found constituents in the analyzed calculi from the patients from Macedonia) using artificial neural networks (ANN).