Infrared and Raman spectra of strontium and barium pimelates monohydrates.

The salts of dicarboxylic acids with alkaline earth metals are not very thoroughly studied and only a few such compounds are well known and characterized. In this work a detailed examination of the infrared spectra recorded at room temperature (RT) and at the liquid nitrogen boiling temperature (LNT) and Raman spectra (at room temperature) of the monohydrates of strontium and barium pimelates, [Sr(µ6-C7H10O4)(H2O)]n and [Ba(µ6-C7H10O4)(H2O)]n respectively, has been carried on. These isostructural salts are important nucleating agents for processing of isotactic polypropylene (iPP). The vibrational spectra of the two salts have been interpreted by using factor group analysis. For more correct and unequivocal interpretation of the vibrational spectra, samples containing partially and almost fully deuterated crystallization water have also been prepared and studied. The effect of the metal ion on the vibrations of the pimelic acid ion as well as the strength of the hydrogen bonds formed by the crystallization water molecule has been discussed.

Vibrational spectra of Mg2KH(XO4)2·15H2O (X=P, As) containing dimer units [H(XO4)2].

Infrared and Raman spectra of Mg2KH(PO4)2·15H2O and Mg2KH(AsO4)2·15H2O and a series of their partially deuterated analogues were recorded and analyzed. Compounds of the type Mg2KH(XO4)2·15H2O (X=P, As) are little-known and a rare case of phosphate and arsenate salts containing dimer units [H(XO4)2] 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 XO4 groups connected in a dimer through a proton are not consistent with the presence of X-O-H covalent linkage and C1 crystallographic symmetry of the XO4 groups. The observation of a singlet Raman band for the ν1(XO4) mode as well as the absence of substantial splitting of the ν3(XO4) modes and IR activation of the ν1(XO4) mode suggest that the dimer units [H(XO4)2] are most probably symmetric rather than non-symmetric ones. It was found that, in the vibrational spectra of Mg2KH(AsO4)2·15H2O, both ν1(AsО4) and ν3(AsО4) modes have practically the same wavenumber around 830cm-1. It was also established that the ν4(PО4) modes in the deuterated hydrogendiphosphate compound are strongly coupled, most probably with HDO and/or D2O librations. As a whole, the spectral picture of Mg2KH(XO4)2·15H2O (X=P, As) very much resembles that observed for the struvite type compounds with the formula KMgXO4·6H2O (X=P, As) which do not contain X-OH groups. This means that vibrations of the dimers [H(XO4)2] play a relatively small part in the general spectral appearance.

A simple chemical method for preparation of hydroxyapatite coatings on Ti6Al4V substrate.

A novel, simple and economical chemical bath method for deposition of calcium hydroxyapatite coating has been developed. The coatings were prepared from EDTA solutions in alkaline media on Ti6Al4V substrates. The method is based on thermal dissociation of the Ca(EDTA)2- complex at 65-95 degrees C. Two chemical baths with and without presence of Na+ and Cl- were used for the deposition. The Rutherford back scattering study shows that the coating material from bath which contained sodium and chlorine ions have their presence in the coated material. The bath which has been prepared with potassium substituting sodium and nitrate substituting chlorine produced coatings with better stoichiometry, with Ca/P=1,67. The X-ray analysis revealed that the calcium hydroxyapatite coatings have preferred crystal orientation in the 002 direction.