Objectives:The polyoxometalates are a class of inorganic compounds with controllable shapes and sizes, and with excellent properties that make them attractive for various applications. This study is aimed at the comparative UV and IR spectra of Keggin type polyoxometalates. Methods: Compounds under (UV and IR) investigations were divided into several groups to highlight similarities between compounds or classes of compounds for the same category. There are four types of saturated Keggin structures and six lacunar compounds included in this study. The study begins with the UV investigations on aqueous solutions with 10 -5 M concentration for these compounds. IR spectra were recorded as KBr pressed pellets. Results: The UV spectras presents large strong peaks between 185-195 nm corresponding to W = Od bonds, between 251-268 nm for W-O-W bridge bonds, depending on heteroatom types (As, Sb). The unsaturated cryptand ligand having Co 2+ coordinated presents the most intense peak, due to the involvement of oxygen atoms from terminal W = Od coordinative bonds with high electronic densities in coordination of W-O-Co bond. The IR spectra present many peaks that are associated as follows: for terminal bonds W = Od, 955-970 cm -1 ; for W-O-W bridging bonds, 790-910 cm -1 ; for W-O-As/Sb bonds to heteroatom, 690-760 cm -1 . Vibrations of the bonds between heteroatoms and oxygen (As/Sb-O) appear around 620-660 cm -1 . Conclusions: Similarities appear from the recorded spectra, between compounds of the same class, by category association. Very fi ne displacements of peaks that occur explain the infl uence of heteroatoms, addenda atoms or coordinated cations.

The aim of this study is to confirm the formation of inclusion complexes between bifonazole (BFZ) and different cyclodextrin (CD) derivatives. BFZ, an imidazole antifungal derivative, is a very hydrophobic compound, which is a major drawback in obtaining topical pharmaceutical formulations with optimal bioavailability. CDs may increase local drug delivery by enhancing the drug release and/or permeation. Several native and derivatized CD derivatives were tested in the experiments. The binary systems between BFZ and CDs were prepared in two molar ratios by physical mixing methods. The physicochemical properties of these complexes were studied by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy methods. The results showed favorable molecular interaction between the components in solid state and in solution. 1 H NMR-CD titrations and molecular modeling study showed that the most stable complex was obtained when using γ-CD. The Job's method and 2D NMR spectroscopy support the 2 : 1 stoichiometry of the BFZ : γ-CD complex.Keywords: bifonazole; cyclodextrins; differential scanning calorimetry; Fourier transform infrared spectroscopy; H NMR-CD titrations КАРАКТЕРИЗАЦИЈА НА ИНКЛУЗИОНИ КОМПЛЕКСИ МЕЃУ БИФОНАЗОЛ И РАЗЛИЧНИ ЦИКЛОДЕКСТРИНИ ВО ЦВРСТА СОСТОЈБА И ВО РАСТВОРЦелта на ова истражување е да се потврди образувањето на инклузиони комплекси меѓу бифоназол (BFZ) и различни циклодекстрински (CD) деривати. BFZ, кој претставува имидазолски фунгициден дериват, е силно хидрофобно соединение, што претставува голем недостаток при добивање топични фармацевтски препарати со оптимална биорасположливост. CD може да ја зголеми локалната испорака на лекот со подобрување на ослободувањето и/или пропустливоста на лекот. Експериментално беа тестирани неколку нативни и дериватизирани CD. Бинарните системи меѓу BFZ и CD беа подготвени во два моларни односа со методи на физичко мешање. Физичкохемиските својства на овие комплекси беа испитувани со диференцијална скенирачка калориметрија (DSC), Фуриеова трансформна инфрацрвена (FTIR) спектроскопија и со нуклеарно-магнетни резонантни спектроскопски методи. Резултатите покажуваат позитивна молекулска интеракција меѓу компонентите во цврста фаза и во раствор. Титрациите на 1 H NMR-CD и испитувањето со молекулско моделирање покажуваат дека најстабилен комплекс се добива со

Polyoxometalates are important inorganic compounds with a broad range of pharmacological properties, including antiviral, antibacterial, antiprotozoal

Background: Polyanions are a special category of coordination compounds with a large development in last years. By coordination of metal oxoions at the lacunary polyoxometalates are obtained new compounds which are studied for theirs possible antitumoral and antiviral activities. The polyoxometalates can bind cations by oxygen atoms from their saturated surface structure or by embedding in vacant sites. Material and method: The methods used for determining cation coordination with the unsaturated polyoxotungstate are spectrophotometry and conductometry. The solutions used in this study were: for ligand a solution of K 27 [KAsW 40 O 140 ] and for cation a solution of K 2 [PtCl 6 ]. The variation of electrical conductivity of ionic species found in solution, caused by their concentrations, decreases during the complex formation, which was determined by conductometry. The spectrophotometric assay was performed to verify ratios between cation:ligand combination, determined by conductometry. Results:The graphical representations of conductivity function of number of moles of added titrant solutions emphasize that there are two types of coordination compounds with two different combination ratios ligand:cation at 1:2 or 1:4. The spectrophotometric determination performed, confi rmed these ratios. Conclusions: There are two types of coordination complexes, and the ligand:cation ratios are well known for encrypting polyoxotungstates type used in the study. Besides the main active position SC where K + alkaline cation is coordinated, it has four active stand side S 1-4 , which can coordinate metal cations, depending on the size of their cationic radius and the electronic charge they hold. Th ey are assemblies of polyhedra containing inside the X heteroatom (primary or secondary) and the M addenda atoms (transition metals, hexacoordinated). Th e structure is delimited by oxygen atoms, with low basicity, relatively inactive, which does not favor further polymerization. Th is is the key for stability of these compounds [1,2].Th e polyoxotungstates are a subdivision of this class, where the addenda atom M is represented by W. Basic element of structure is the WO 6 octahedron coordinated around the XO p heteroatoms (Figure 1a and 1b).Th ese compounds have saturated or unsaturated structures obtained by removing one or several WO 6 octahedrons. Th e unsaturated polyoxometalates are a special category of coordination compounds because of their physical and chemical properties, based on unsaturated structures [3]. Th e terminal oxygen atoms from their structures give them a high coordinative capacity for many cations [4,5]. After coordination, the structures do not change; only little displacements of atoms occur. Depending on the degree of unsaturated structures, in lacunae, a high density