Afanasenko E. Synthesis, structure, biological activity of supramolecular coordination tartrato-, malatogermanates,stannates.

There was developed an original general synthesis method that combines essential Ge(IV)/Sn(IV), “life metals” Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and two types of bioligands: chelating polydentate tartaric/malic acid and bidentate heterocyclic 1,10-phenanthroline/2,2`-bipyridine as parts of the supramolecular salts with complex 1,10-phenanthroline/2,2`-bipyridine cations of 3d-metals/ protonated phenanthroline molecule and complementary tartrate(malato-)germanate/stannate anions. Totally 21 compounds were synthesized and completely characterized by the methods of X-Ray, elemental, thermogravimetric analyses, IR-, MS-spectroscopy, Hirshfeld surface analysis and density functional theory calculations (DFT). It was established that structural and compositional features of the constructional metal-chelate blocks (cations and anions) influence the realization of intermolecular noncovalent interactions (electrostatic, hydrogen, staking) and formation of the crystalline supramolecular structures. The role of the starting acid on their formation of anions has been revealed after comparing of the supramolecular salts between each other. Both acids – malic and tartaric are dicarbonic, contain one/two hydroxylic groups, respectively. This influences the type of the anion: tartratic acid is tetradental, performs a bridging function and forms four types of dimeric germanate [Ge2(OH)2(μ-Tart)2]2-, [Ge2(OH)(H2Tart)(μ-Tart)2]3-, [Ge2(OH)(HTart)(μ-Tart)2]4-, [(μ-O){Ge2(OH)(μ-Tart)2}2]4- and one type of stannate [Sn2(μ-Tart)2(Н2Tart)2]4- anions. Potentially tridentate malic acid shows itself only as bidentate ligand and forms similar octahedral anions [Sn(HMal)2(Mal)]3- and [Ge(HMal)(Mal)2]4- regardless the central atom. Change in the condition of synthesis and special features of 1,10-phenanthroline promote the formation of [(μ-O){Ge2(OH)(μ-Tart)2}2]4- anion, in which dimeric fragments are connected with bridging oxygen atom and protonated 1,10-phenanthroline acts as a cation. Location of its molecules in the outer sphere causes presence of the stacking interactions between aromatic rings and increases the total biological activity of compound. The following screening of tartratogermanates (stannates) with 1,10-phenanthroline cations of Fe(II), Co(II), Ni(II), Cu(II), Zn(II) revealed its antimicrobial activity against 8 opportunistic pathogens. Decreasing of the activity is observed in the row of tartratostannates with the similar anion: Zn>Cu~Co>Ni>Fe. This correlates with the quantum-chemical calculations in which [Zn(phen)3]2+ has the highest average value of electrostatic potentials, molecular polarity index, volume, total surface area. As a result, there was made an alike sequence of tartratogermanates that depends from the composition and structure of anion: [Ge2(OH)2(μ-Tart)2]2- > [Ge2(OH)(HTart)(μ-Tart)2]4- ~ [Ge2(OH)(HTart)(μ-Tart)2]4-.It was established that synthesized compounds can influence the activity of α-Lrhamnosidases Penicillium tardum, Penicillium restrictum, Eupenicillium erubescens and Cryptococcus аlbidus. Depending on the strain, they show properties of activators or inhibitors. Their effectiveness is determined by the summation of all biologically active components, hydrophilic nature of anions, hydrophobic – cations and indicates a complex mechanism of their interaction with the enzyme.