The quantitative assessment of intermolecular interactions and their cooperative effects has been performed in spirohydantoin-based model compounds, 3-benzoyl-1,3-diazaspiro[4.5]decane-2,4-dione (1) and 3-(4-fluorobenzoyl)-1,3-diazaspiro[4.5]decane-2,4-dione (2), through single crystal X-ray crystallography and quantum chemical...

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Green hydroxyapatite ceramics were obtained by cold uniaxial and isostatic pressing of hydrothermally synthesized powders, pure hydroxyapatite and hydroxyapatite doped with Ag + , Cu 2+ and Zn 2+ ions. The ceramics were conventionally and microwave sintered and analyzed by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction analysis, and energy-dispersive X-ray spectroscopy. The effect of doping on the mechanical properties of the obtained hydroxyapatite/tricalcium phosphate ceramics was examined by comparing their average grain size, porosity and values of the hardness and fracture toughness. The results showed that doping with Cu 2+ ions caused the lowest porosity of the ceramics and the highest values of hardness and fracture toughness. The ceramics obtained from hydroxyapatite doped with Ag + and Zn 2+ ions exhibited worse mechanical properties due to the higher porosity even in the case of microwave sintering, which provide denser ceramics than conventional sintering.

A series of cycloalkane-5-spirohydantoins bearing a halogeno substituted benzyl group (X = Cl and Br) in position 3 has been synthesized and their structures (1-6) have been determined by single crystal X-ray diffraction method. These compounds have multiple functional groups, which allow a greater competition and/or cooperation among the different intermolecular interactions in formation of their crystal structures. The molecules are linked together by paired N-H•••O hydrogen bonds in R2 2 (8) rings, while the C-H•••O interactions lead to their further association into double chains. The contribution of the cycloalkyl ring depends on its conformational flexibility and the multiple C-H donor implications. In the case of compounds 1-4 bearing the cyclopentyl or the cyclohexil ring, halogen bonding (X•••O) interactions give rise to a supramolecular pseudo-hexagonal network. In addition, the C-H•••X interactions with a higher degree of multifurcation at the halogen acceptor have an important role in formation of the crystal structure. Regarding compounds 5 and 6 with the cycloheptane ring, the X•••O interaction is absent and, along with the C-H•••X interactions, these compounds realize an alternative crystal structure with emphasis on the X•••π interactions. The lattice energies of all these crystal structures, as well as intermolecular pair energies, have been calculated using PIXEL and further partitioned into coulombic, dispersive, polarization and repulsive factors. The crystal structures have also been subjected to Hirshfeld surface analysis which reveals that approximately 75% of the close contacts correspond to relatively weak interactions. The application of both concepts has provided a new insight into relationships between molecular and crystal structure of the hydantoin derivatives.

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Two series of cycloalkanespiro-5-hydantoins, namely cyclohexanespiro-5-hydantoins and cycloheptanespiro-5-hydantoins with a 4-substituted benzyl or a 2-(4-substituted phenyl)-2oxoethyl group at N3 position, were synthesized and their effects on proliferation of human colon (HCT-116), leukemia (K562) and breast (MDA-MB-231) cancer cell lines were tested.For comparison, we also described the 5,5-diphenylhydantoin analogues. The structural features of the investigated compounds were characterized by elemental analysis, FT-IR, UV-Vis, 1 H and 13 C NMR spectroscopy and X-ray crystallography. Regarding their structureactivity relationships, it was shown that the substitution on the benzyl moiety with the methoxy, chloro or bromo group potentiated the antiproliferative activity relative to the parent compounds, while an increase in the size of the cycloalkyl group resulted mostly in a decrease of the antiproliferative activity. The single crystal X-ray analysis revealed the existence of dimers and chains formed by the N-H•••O hydrogen bonds. The analysis of the molecular descriptors of Lipinski demonstrated that all investigated compounds obeyed the rule of five. To further understand their geometry and electronic structure, DFT calculations with B3LYP method using 6-311++G(d,p) basic set were performed. In this context, the UV-Vis spectra of the investigated compounds were analyzed in detail, whereby the predicted absorption spectra from DFT calculation matched the experimentally obtained ones, with a good correlation. The interesting physico-chemical and pharmacologically relevant properties of the investigated compounds warrant their further investigation.

Zinc oxide (ZnO) nanoparticles were obtained by thermal decompo-sition of one-dimensional zinc-benzenepolycarboxylato complexes as single-source precursors at 450 ?C in air atmosphere. The mechanism and kinetics of thermal degradation of zinc-benzenepolycarboxylato complexes were analyzed under non-isothermal conditions in air atmosphere. The results of X-ray powder diffraction and field emission scanning electron microscopy revealed hexagonal wurtzite structure of ZnO with an average crystallite size in the range of 39-47 nm and similar morphology. The band gap and the specific surface area of ZnO nanoparticles were determined using ultraviolet-visible diffuse reflectance spectroscopy and Brunauer, Emmett and Teller method, respectively. The photo-luminescent, photocatalytic and antimicrobial properties of ZnO nanoparticles were also examined. The best photocatalytic activity for degradation of C. I. Reactive Orange 16 dye has been observed for ZnO powder where crystallites form the smallest agglomerates. All ZnO nanoparticles showed excellent inhi-bitory effect against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. 451-03-68/2020-14/200287 and Grant no. 451-03-68/2020-14/200135)]