The present thesis deals with systematic investigations of hexafluorosilicates with organic, biologically active cations in view of their use as caries protective agents. The methods of synthesis of pyridinium, dipyridinium and polyguanidinium hexafluorosilicates with a practically quantitative yield are proposed. The complexes were characterized by elemental analysis, 1H, 19F NMR, IR, mass-spectrometry, potentiometry, thermogravimetric analysis, X-ray crystallography. The structural study revealed the details of the anion binding and solid state supramolecular architectures provided by the combination of the plethora of intermolecular interactions including strong charge assisted and conventional hydrogen bonds of NH…F, OH…F types along with O…Br contacts and - interactions. Hydrogen bond systems were found to play the major role in structural organization and stabilization of salts structure. For complexes [2,6-(HOCH2)2C5H3NH]2SiF6 and [2-CH3-3-OH-4,5-(HOCH2)C5HNH]2SiF6 the involvement of hydroxyl groups in the cation - anion H-binding was demonstrated for the first time. Singlet type vibration bands ?(SiF) and ?(SiF2) for hexafluorosilicate anions in the IR-spectra of the salts with cetylpyridinium and guanidine containing cations reflect apparently proximity of anions structure to the idealized Oh-symmetry. The hexafluorosilicates salts revealed a tendency toward solubility decrease with increase of H-donors number in the cations moieties. In the case of cetylpyridinium hexafluorosilicate the strong inter-ionic H-bonds must be absent (week interactions between SiF62- anion and sp2-hybridized C-H groups can be observed) and relatively low solubility of I can be explained the substantial lipophilic effect of cetylic radical -C16H33. The solubility data for hexafluorosilicates with guanidine containing cations illustrate the so-called Lipinski "rule of 5" that predicts the low water solubility and absorption for compounds with the number of H-donors NH > 5. The pH values of 0.001 M aqueous solutions of hexafluorosilicates are independent from the nature of the cation and are in the range 2.95 - 3.35, which implies that the solutions are in equilibrium with respect to hydrolysis. In dilute water solutions (1 10-4 М), salts underwent practically quantitative hydrolysis with formation of fluoride-ions and soluble form of silicon dioxide, which catalyzed the process of formation of calcium phosphate sediment from saliva. High degree of conversion of SiF62- anions into silicon dioxide (silicic acid) in dilute aqueous solutions facilitates, an effective release of fluoride ions, that together with formation of silica, should provide caries-protected effect of studied compounds. The results of PASS-screening demonstrated the high probability of sialagogue and immunostimulant activity for all heterocyclic bases, which entered in compositions of "onium" cations. The data of PASS-screening indicate a high probability of the existence of anti-inflammatory activity of pyridine derivatives and isomeric 2,2'-, 4,4'-dipyridine and 2,2'-, 4,4'-dipyridineketones, containing the residue of acetic and propionic acids. It is shown that the introduction of the second residue of acetic acid in the structure of the molecule and the location of propionic acid residue in the ?-position relative to the pyridine nitrogen atom greatly increases the likelihood of anti-inflammatory activity. The results of the experimental toxicity study in rats for cetylpyridinium hexafluorosilicate (oral route) show that salt refers to the toxicity class III (204,43 mg/kg, moderately toxic compound). According to variability of lethal doses, cetylpyridinium hexafluorosilicate is referred to compounds having no high potential risk of poisoning and development. The estimated rates of toxicity and hazard of cetylpyridinium hexafluorosilicate show that it does not represent a special hazard to humans. These are relatively low medium lethal dose of absolute toxicity, total toxicity index and high indexes of acute toxic effects zone of cetylpyridinium hexafluorosilicate under the oral route of administration. All hexafluorosilicates significantly improve biochemical parameters in dental pulp of animals and their ability to mineralize, reduce the depth and the number of dental caries, provide efficiency of caries prevention up to 80 %; introduced - into scientifically research work and educational processes of the departments of pharmaceutical direction; direction - pharmacy.
