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147 146 М30 М34 Dicalcium phosphate (DP) materials, of which brushite and monetite were the most known, have been intensively studied for several decades because of excellent resorptive and osteoconductive properties that can satisfy the requirements needed for various medical applications, such as bone cements, coatings of metallic implants and bone grafts [1,2]. Brushite and monetite are the dihydrated (CaHPO4·2H2O) and anhydrous (CaHPO4) forms of DPs, respectively, which showed much better resorption due to higher solubility in comparison to the hydroxyapatite (HAp) and tricalcium phosphate (TCP) [2]. In this study, the effect of different post-synthesis treatments on composition and morphology of four brushite/monetite powders, were analyzed. All the powders have been prepared by modified precipitation method described previously [3] with molar ratio of starting reagents (NH4)2HPO4 and Ca(NO3)2·4H2O being 7:10. After filtering, powder I was obtained by drying the precipitate at 105 °C for 4 h, while powder II was obtained by precipitate freezing at ‒10 °C for 72 h, followed by drying at room temperature for 72 h. By drying the precipitate at 110 °C for 24 h and 105 °C for 3 h, powders III and IV were obtained, respectively. X-ray powder diffraction (XRPD) revealed that all the powders are two-phase systems consisting of brushite and monetite: 98.8 mas.% brushite and 1.2 mas.% of monetite in I, 97.7 mas.% brushite and 2.3 mas.% of monetite in II, 66.7 mas.% brushite and 33.3 mas.% of monetite in III and 45.9 mas.% brushite and 54.1 mas.% of monetite in IV. Field Emission Scanning Electron Microscopy (FESEM, Figure 1) showed that particles of prepared materials form the agglomerates in the form of triangular plates. In addition, materials were analyzed for their spectral, thermal and textural properties.

197 М60 М64 In recent years, thermal decomposition studies of transition metal complexes with benzenepolycarboxylate ligands have become an area of a great importance due to the possibility of obtaining useful metal oxides with desirable electrical, magnetic and catalytic properties [1]. As a contrast to conventional methods for the preparation of metal oxides, such as hydrothermal or sol–gel treatment, thermolysis is faster, more efficient and environmentally friendly. Mn(II)–dipya (dipya = 2,2’-dipyridylamine) complex with tetraanion of 1,2,4,5-benzenetetracarboxylic (pyromellitic, H4pyr) acid, [Mn2(dipya)2(pyr)(H2O)2], has been prepared and characterized by elemental, spectral and microscopy analyses. Direct thermolysis of the complex up to 1200 °C in an air atmosphere yielded spinel Mn3O4 oxide material. The obtained Mn3O4 has been characterized for its structural, spectroscopic, morphological and optical properties. The possibilities of using this oxide as photocatalyst or co-photocatalyst for removing textile organic dyes, as well as inorganic pigmentary material, were also investigated and discussed.

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 studies. In both crystal structures, molecules generate the same hydrogen-bonded centrosymmetric R22(8) synthon. The extended supramolecular architectures depend on the C-HMIDLINE HORIZONTAL ELLIPSISO, C-HMIDLINE HORIZONTAL ELLIPSIS pi, stacking interactions and parallel interactions at large offsets, which lead to molecular sheets and further, with the assistance of the C-HMIDLINE HORIZONTAL ELLIPSISF interaction in the case of 2, to three-dimensional networks. Electrostatic potential maps have indicated that formation of the intermolecular FMIDLINE HORIZONTAL ELLIPSISF interaction in the crystal structure of 2 results in a new region with a larger surface area and a higher negative potential in comparison to the individual fluorine atoms. Establishment of this interaction leads to strengthening of the interaction of one of the fluorine atoms with a third molecule from the environment which does not interact with both of them. When this third molecule interacts with both fluorine atoms simultaneously, the calculations have shown that the effect of strengthening of the individual interactions due to formation of the FMIDLINE HORIZONTAL ELLIPSISF interaction is absent.

Synthetic hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is very similar to the inorganic part of the bones and teeth of mammals. It is a well-known biomaterial with good biocompatibility, osteoconductivity and bioactivity. Nifuroxazide (C12H9N3O5, NFX) is a broad-spectrum antibacterial drug and poorly soluble in water. In order to increase the solubility of NFX, nano-sized HAp powder and raw NFX drug were mixed giving, as a result, a HAp/NFX conjugate. Characterization of the raw materials and the obtained conjugate confirmed the integration of NFX on the HAp surface. An in vitro study of drug release in simulated stomach acid and intestinal fluid showed a much faster release of NFX from HAp surface than those of the raw drug. The HAp/NFX conjugate showed excellent inhibitory effects against Gram-positive bacterium Staphylococcus aureus, Gram-negative bacterium Escherichia coli and yeast Candida albicans, proving the nano-sized HAp powder as a promising drug carrier.

Orange single crystals of new polymeric cobalt(II) complex {[Co(bipy)(H2O)4]2[Co(μ-mell)(H2O)2 ]· 10H2 O}n, 1, were synthesized by slow evaporation method at room temperature (bipy = 2,2′-bipyridine, mell = hexaanion of mellitic acid) and its crystal structure was determined by single-crystal X-ray diffrac- tion. The complex 1 was characterized based on elemental analysis, FTIR spectroscopy and thermal (TG/DTA) analysis followed by computational analysis of noncovalent interactions and quantum chemical calculations of interaction energies. In 1, two crystallographically different Co(II) atoms adopt a deformed octahedral geometry, while bridging mell acts as a tetrakis monodentate ligand allowing the development of wavy-like anionic chains running along [100] direction. The 3D supramolecular network of 1 is com- posed of alternating supramolecular and water layers connected by hydrogen bonds. The supramolecular layer is formed of ionic interactions between complex cations and polymeric complex anions, established mainly through O–H···O hydrogen bonds, as well as stacking interactions between bipy ligands, while the water layers are comprised of hydrogen bonded lattice water molecules. Upon heating up to 1200 °C in nitrogen and air atmosphere, complex 1 showed multiple-step degradation that resulted in the for- mation of Co and Co3O4, respectively. Computed Hirshfeld surfaces and 2D fingerprint plots indicated that O–H···O hydrogen bonds are the most dominant in the crystal structure, while the shape index and curvedness mapped on the Hirshfeld surfaces of 1 revealed that stacking interactions have an important role in the stabilization of the crystal packing. Quantum chemical calculations showed that, aside from ionic hydrogen-bonded interaction between cation and anionic polymer, the important role in the sta- bility of supramolecular structure of 1 is played by hydrogen bonds of cation and anionic polymer with lattice water, as well as by stacking interactions between bipy ligands. Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/5017]

Green hydroxyapatite ceramics were obtained by cold uniaxial and isostatic pressing of hydrothermally synthesized powders, pure hydroxyapatite and hydroxyapatite doped with Ag+, Cu2+ and Zn2+ 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 Cu2+ 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 Zn2+ ions exhibited worse mechanical properties due to the higher porosity even in the case of microwave sintering, which provide denser ceramics than conventional sintering.

Two pyridone derivatives, bearing the pyridinium moiety (1), or dimethylpyridinium moiety (2), have been synthesized and their crystal structures have been determined. The compounds crystalize in hydrated zwitterionic forms with either two (1•2H2O) or four (2•4H2O) water molecules. The zwitterionic networks contain different types of water clusters, generated into channels, incorporating them into the network by sandwiching. The type of channel depends on the crystal lattice and the nature of non-covalent interactions established between zwitterions as well as the number of water molecules incorporated into the architecture. 1 affords tubes filled in with water channels formed by water tetramers, contrary to 2, which affords a layered network altering the zwitterionic layer and the layer formed by water tetramers and hexamers. A detailed study of intermolecular interactions of both crystal structures and a quantification of interaction energies has been performed using PIXEL lattice energy calculations, giving an insight to a quantitative evaluation of interactions through Coulombic, disperse, repulsion and polarization energies. The strongest pairwise, in both structures, is found to be a dipole–dipole interaction between oppositely charged heterocyclic rings. The differences in the crystal packings of these hydrates have been elucidated by the fingerplot analysis. The comparative studies between experimental and calculated (DFT) data of molecules 1•H2O and 2•4H2O for systems of different complexity are performed. Furthermore, correlations of experimental and calculated bond lengths and the simulation of compound solvation with the CPCM model are done. This is the peer-review version of the article: Mašulović, A. D., Lađarević, J. M., Radovanović, L. D., Vitnik, Ž. J., Vitnik, V. D., Rogan, J. R.,& Mijin, D. Ž. (2021). Charge assisted assembly of zwitterionic pyridone hydrates. Journal of Molecular Structure, Elsevier., 1237, 130419. [https://doi.org/10.1016/j.molstruc.2021.130419] The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/4506] Supporting information: [https://cer.ihtm.bg.ac.rs/handle/123456789/4508] Related crystallographic data (CCDC 2057269): [https://cer.ihtm.bg.ac.rs/handle/123456789/4509] Related crystallographic data (CCDC 2057270): [https://cer.ihtm.bg.ac.rs/handle/123456789/4510]

Zinc oxide (ZnO) nanoparticles were obtained by thermal decomposition of one-dimensional zinc?benzenepolycarboxylato complexes as single- -source precursors at 450 ?C in an air atmosphere. The mechanism and kinetics of thermal degradation of zinc?benzenepolycarboxylato complexes were analyzed under non-isothermal conditions in an 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 UV?Vis diffuse reflectance spectroscopy and the Brunauer, Emmett and Teller method, respectively. The photoluminescent, photocatalytic and antimicrobial properties of the ZnO nanoparticles were also examined. The best photocatalytic activity in the degradation of C. I. Reactive Orange 16 dye was observed for the ZnO powder where the crystallites form the smallest agglomerates. All ZnO nanoparticles showed excellent inhibitory effect against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli.

A racemic spirohydantoin derivative with two aromatic substituents, a tetralin and a 4-methoxybenzyl unit, was synthesized and its crystal structure was determined. To define the relationship between molecular stereochemistry and spatial association modes, development of the crystal packing was analyzed through cooperativity of intermolecular interactions. Homo and heterochiral dimeric motifs were stabilized by intermolecular N−H⋅⋅⋅O, C−H⋅⋅⋅O, C−H⋅⋅⋅π interactions and parallel interactions at large offsets (PILO), thus forming alternating double layers. The greatest contribution to the total stabilization came from a motif of opposite enantiomers linked by N−H⋅⋅⋅O bonds (interaction energy=−13.72 kcal/mol), followed by a homochiral motif where the 4-methoxybenzyl units allowed C−H⋅⋅⋅π, C−H⋅⋅⋅O interactions and PILO (interaction energy=−11.56 kcal/mol). The number of the contact fragments in the environment of the tetralin unit was larger, but the 4-methoxybenzyl unit had greater contribution to the total stabilization. The statistical analysis of the data from the Cambridge Structural Database (CSD) showed that this is a general trend. The compound is a potential inhibitor of kinase enzymes and antigen protein-coupled receptors. A correlation between the docking study and the results of the CSD analysis can be drawn. Due to a greater flexibility, the 4-methoxybenzyl unit is more adaptable for interactions with the biological targets than the tetralin unit. This is the peer-reviewed version of the article: Anita M. Lazić, Ivana S. Đorđević, Lidija D. Radovanović, Dragan M. Popović, Jelena R. Rogan, Goran V. Janjić, Nemanja P. Trišović, Self-Assembly and Biorecognition of a Spirohydantoin derived from α-Tetralone: Interplay between Chirality and Intermolecular Interactions, ChemPlusChem, 2020, 85, 6, 1220-1232, doi: [https://doi.org/10.1002/cplu.202000273] The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/3638]

A terephthalate-bridged heteronuclear Cu(II)–Mn(II) complex [Cu2Mn(dipya)2(tpht)3]n, I, where dipya is 2,2′-dipyridylamine and tpht is the anion of 1,4-benzenedicarboxylic (terephthalic, H2tpht) acid was synthesized under hydrothermal conditions. The obtained complex I was characterized by a single-crystal X-ray diffraction, FTIR spectroscopy, TG/DSC analysis and magnetic measurements. The Cu(II) and Mn(II) metal centers adopt distorted octahedral geometry and they are linked by bridging tpht ligands. Two crystallographically different tpht anions are coordinated as tridentate and hexadentate ligands forming two-dimensional layers. The layers are interconnected by hydrogen bonds and additionally stabilized by non-covalent C–H···π interactions. The measurements of magnetic susceptibility proved that I is an almost perfect paramagnet. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45007]

Four novel manganese(II) complexes with 2,2′-dipyridylamine (dipya) and various benzenedicarboxylate, BDC, ligands as anions of phthalic (pht), isophthalic (ipht) and terephthalic (tpht) acids were hydrothermally synthesized, namely, [Mn(dipya)(pht)(H2O)]2 (1), [Mn(dipya)(ipht)]n (2), [Mn(dipya)2(tpht)]n (3), and [Mn(dipya)(H2O)4](tpht) (4). All complexes were characterized by single-crystal X-ray diffraction, TG/DSC analysis and IR spectroscopy. The obtained complexes display a plenty of different structural features, including geometry of central metal atoms, BDC coordination modes and crystal packing. The coordination numbers of Mn(II) are different: 5 (in 2), 6 (in 3 and 4) and 7 (in 1). 3D networks in 1–4 are determined by strong non-covalent interactions. A survey of the Cambridge Structural Database for BDC complexes was performed in order to analyze orientation of COO groups. The energies of various BDC conformers were calculated by the second order Moller–Plesset perturbation theory and three hybrid HF/DFT methods with 6-311G∗∗ basis set. To explain different behavior, BDC ions were also examined by Localized Molecular Orbital Energy Decomposition and Natural Bond Orbital analyses. Experimental and calculated geometries are in agreement, showing that tpht and ipht anions prefer the planar conformation, while in pht anions COO groups are inclined and make complementary angles relative to the aromatic rings.

A series of five derivatives of the anticonvulsant drug phenytoin was synthesized, and their crystal structures were determined. The relationship between the molecular and crystal structure of the investigated compounds was rationalized in the context of contribution of intermolecular interactions and supramolecular structural motifs. The conformational preferences were analyzed by comparing the rotational freedom of the phenyl groups in the investigated compounds with 5,5-diphenylhydantoins from the Cambridge Structural Database. With the exception of compound 3 bearing the cyclopropyl group, the crystal packing of the investigated compounds contains centrosymmetric dimers linked by paired N–H···O hydrogen bonds, which further self-organize through pairs of C–H···O interactions and a parallel interaction of two phenyl rings at a large offset into chains running along the c-axis. The principal feature of the crystal structure of compound 3 is formation of the chains by N–H···O hydrogen bonds and C–H···O and C–H···π interactions. The coordination of phenytoin enables more rotational freedom for the phenyl groups. An emphasis was placed on docking of the investigated compounds into the voltage-gated ion channel in the open and closed state. The obtained results indicate that hydrogen bonding and hydrophobic interactions are dominant in stabilizing energetically favored orientations of the investigated compounds bound to the protein. This is the peer-reviewed version of the manuscript: Cryst. Growth Des. 2019, 19, 4, 2163-2174, [https://doi.org/10.1021/acs.cgd.8b01776] The published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3277]

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)-2-oxoethyl 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 structure–activity 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. Published version: [http://technorep.tmf.bg.ac.rs/handle/123456789/4324] This is the peer-reviewed version of the following article: Lazić A, Radovanović L, Božić B, Božić-Nedeljković B, Vitnik V, Vitnik Ž, Rogan J, Valentić N, Ušćumlić G, Trišović N. Synthesis, structural characterization, DFT calculations and antiproliferative evaluation of novel spirohydantoin derivatives containing a substituted benzyl moiety. in Journal of Molecular Structure. 2019;1180:48-62. [https://doi.org/10.1016/j.molstruc.2018.11.071]

A series of new zinc complexes containing the 2,2'-dipyridylamine (dipya) ligand and anions of four benzenepolycarboxylic (BPC) acids, namely phthalic (H(2)pht), isophthalic (H(2)ipht), terephthalic (H(2)tpht) and pyromellitic (H(4)pyr), have been synthesized by ligand exchange reactions. The complexes were characterized based on elemental analysis, FTIR spectroscopy and thermal (TG/DSC) analysis. The complexes were found to have the formulae [Zn(dipya)(pht)] (1), [Zn(dipya)(ipht)](n) (2), {[Zn(dipya)(tpht)]center dot H2O}(n) (3) and [Zn-2(dipya)(2)(pyr)] (4). Compounds 2 and 3 have been obtained as single crystals and their crystal structures were determined from X-ray diffraction data. In both structures the coordination number of the Zn atoms is five and they are linked by bridging BPC ligands. In 2, the ipht ligand is coordinated in a tridentate manner via chelate and monodentate COO groups, whereas two crystallographically different tpht ligands in 3 are coordinated as bis-chelate and bis-monodentate ligands, respectively. These combined modes of ipht and tpht anions resulted in zigzag chains of 2 and 3. Two-dimensional pseudo-layers in 2 and a three-dimensional network in 3 are governed by hydrogen bonds and C-H center dot center dot center dot O interactions which are formed between the zigzag chains, and by additional C-H center dot center dot center dot pi interactions in 3. The antimicrobial activity of complexes 1-4 was screened in vitro against some Gram-positive bacteria (Bacillus subtilis, Enterococcus faecalis, Listeria monocytogenes and Staphylococcus aureus), some Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Salmonella enteritidis) and yeast Candida albicans. Complex 2 showed the most potent inhibitory effect against the tested microorganisms.

The design of mixed-ligand complexes are of increasing interest from fundamental as well as technological and curative aspects. Having that in mind, we studied zinc complex containing 2,2'-dipyridylamine (dipya) and dianion of isophthalic acid (ipht), [Zn(dipya)(ipht)](n), as promising precursor for synthesis of nanostructured metal oxide. In that sense, the mechanism and degradation kinetics of [Zn(dipya)(ipht)](n), was analyzed under non-isothermal conditions in nitrogen and in air atmospheres. Peak deconvolution of the [Zn(dipya)(ipht)](n), decomposition profile, in the form of a derivative thermogram (DTG), in nitrogen atmosphere, revealed the presence of three decomposition steps, while in air five single steps were isolated. In both cases ZnO is formed as residue at 530 degrees C: pure (in air) or in amorphous matrix (nitrogen). In air we obtained well crystalized ZnO nanospheres (-25 nm), by thermal treatment in temperature range 370-530 degrees C showing that this complex could be considered as good precursor for production of nanosized ZnO.

Two new isostructural M(II) (M = Ni, Co) complexes with 2,2'-dipyridylamine (dipya) and dianion of terephthalic acid (?${\rm H_2}\text{tpht}$?), ?${\rm M({dipya})_2 (H_2O)_2 ({tpht}) \cdot 2H_2O}$?, have been synthesized by ligand exchange reaction and characterized by single-crystal X-ray diffraction, FTIR spectroscopy, TG/DSC analysis and magnetic measurements. The crystal structures of ?${\rm M({dipya})_2 (H_2O)_2 ({tpht}) \cdot 2H_2O}$? consist of discrete complex units in which M(II) adopts deformed octahedral geometries. Two dipya ligands and two water molecules are coordinated to M(II) atom, tpht acts as a counter ion, while additional two water molecules remained uncoordinated. By numerous hydrogen bonds, all structural fragments are connected in three different chains which extend along 100, 010 and 001 directions, giving as a result a complex 3D network. The stabilization of 3D structure is accomplished by non-covalent face to face ?$\pi - \pi$? interactions among pyridyl ring of dipya and benzene ring of tpht from adjacent chains. Towards the applied magnetic field, the both complexes exhibited almost perfect paramagnetic behavior Z reakcijo izmenjave ligandov smo sintetizirali dva nova izostrukturna M(II) (M = Ni, Co) kompleksa z 2,2'-dipiridilaminom (dipya) in dianionom tereftaline kisline (?${\rm H_2}\text{tpht}$?),?${\rm M({dipya})_2 (H_2O)_2 ({tpht}) \cdot 2H_2O}$?, in ju okarakterizirali z monokristalno rentgensko difrakcijo, FTIR spektroskopijo, TG/DSC analizo in magnetnimi meritvami. Kristalni strukturi ?${\rm M({dipya})_2 (H_2O)_2 ({tpht}) \cdot 2H_2O}$? sta zgrajeni iz izoliranih kompleksnih enot, v katerih ima M(II) ion popačeno oktaedrično geometrijo. Dva dipya liganda in dve molekuli vode so koordinirani na M(II) ion, tpht je protiion, preostali dve molekuli vode sta v strukturi nekoordinirani. Strukturni fragmenti so povezani preko številnih vodikovih vezi v tri verige vzdolž 100, 010 in 001 smeri, kar vodi do nastanka 3D mreže. Stabilizacija 3D strukture je dosežena z nekovalentnimi ?$\pi - \pi$? interakcijami med piridinskimi obroči dipya ligandov in benzenovih obročev tpht anionov iz sosednjih verig. V magnetnem polju izkazujeta oba kompleksa popolno paramagnetno obnašanje.

The novel polymeric complexescatena-poly[[diaquamanganese(II)]-μ-2,2′-bipyrimidine-κ4N1,N1′:N3,N3′-[diaquamanganese(II)]-bis(μ-terephthalato-κ2O1:O4)], [Mn2(C8H4O4)2(C8H6N4)(H2O)4]n, (I), andcatena-poly[[[aquacopper(II)]-μ-aqua-μ-hydroxido-μ-terephthalato-κ2O1:O1′-copper(II)-μ-aqua-μ-hydroxido-μ-terephthalato-κ2O1:O1′-[aquacopper(II)]-μ-2,2′-bipyrimidine-κ4N1,N1′:N3,N3′] tetrahydrate], {[Cu3(C8H4O4)2(OH)2(C8H6N4)(H2O)4]·4H2O}n, (II), containing bridging 2,2′-bipyrimidine (bpym) ligands coordinated as bis-chelates, have been preparedviaa ligand-exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht2−) anions were found. In (I), two tpht2−anions acting as bis-monodentate ligands bridge the MnIIcentres in a parallel fashion. In (II), the tpht2−anions act asendo-bridges and connect two CuIIcentres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn2(tpht)2(bpym)(H2O)4] entity in (I) and the trinuclear [Cu3(tpht)2(OH)2(bpym)(H2O)4]·4H2O coordination entity in (II) build up one-dimensional polymeric chains along thebaxis. In (I), the MnIIcation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central CuIIcation is also on a special position (site symmetry \overline{1}). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face-to-face π–π interactions [in (I)], forming three-dimensional metal–organic frameworks. The MnIIcation in (I) has a trigonally deformed octahedral geometry, whereas the CuIIcations in (II) are in distorted octahedral environments. The CuIIpolyhedra are inclined relative to each other and share common edges.

The title compound, (Hdipya)(H3pyr), where Hdipya is protonated 2,2’-dipyridilamine and H3pyr is monoanion of pyromellytic acid (H4pyr), was obtained from the reaction mixture containing Zn(II) ions, dipya, Na4pyr (the molar ratio 2 : 2 : 1) and HNO3. The products (micro- and single-crystalline) were characterized by X-ray structure determination, FT-IR spectroscopy and TG/DSC analysis. The most striking structural feature of (Hdipya)(H3pyr) are short inter- and extremely short intramolecular hydrogen bonds. These bonds mutually connect cations and anions making thin layers parallel to the crystallographic (223) plane. Also, quite unusual, linear proton-bound polymeric {H(H2pyr)-}n anions were identified in the structure. The results of crystal structure determination are compared with FT-IR and TG/DSC data. The low position of nas(COO) vibration at 1660 cm-1 is in accordance with strong hydrogen bonding. This value can be used as a measure of C=O bond order, which is calculated to be 1.81. [Projekat Ministarstva nauke Republike Srbije, br. 45007]

Four novel polymeric iron(III) complexes with 2,2'-bipyridine (bipy) and different aromatic polycarboxylato ligands as anions of phthalic (pht), isophthalic (ipht), terephthalic (tpht) and pyromellitic (pyr) acid were synthesized by ligand exchange reaction. The complexes were characterized by elemental and TG/DSC analysis, FTIR and diffuse reflectance UV-Vis-NIR spectroscopy and magnetic susceptibility measurements. Based on the analytical and spectral data, the formulae of the complexes were {[Fe-4(bipy)(2) (H2O)(2)(OH)(6)(pht)(3)]center dot 2H(2)O}(n) (1), {[Fe-4(bipy)(2)(Hipht)(2)(ipht)(2)(OH)(6)]center dot 4H(2)O}(n) (2), {[Fe-4(bipy)(2)(Htpht)(2)(OH)(6)(tpht)(2)]center dot 4H(2)O}(n) (3) and {[Fe-4(bipy)(H2O)(8)-(OH)(4)(pyr)(2)]center dot H2O}(n) (4). All complexes were red brown and low-spin with a distorted octahedral geometry with FeO6 or FeN2O4 chromophores. The polycarboxylato ligands played a bridging role in all cases, whereas monodentate COO groups were present in 2 and 3, while bridging and chelate COO groups were established in 1 and 4. The thermal behaviours of 1-4 were investigated in detail and the molar dehydration enthalpies were calculated. According to the all those results, the structural formulae of complexes 1-4 were proposed.

The structure-property relationship of newly synthesized 3-(4-substituted benzyl)-1,3-diazaspiro [4.4] nonane-2,4-diones was studied by experimental and calculated methods. The prepared compounds were characterized by UV-Vis, FT-IR, H-1 NMR and C-13 NMR spectroscopy and elemental analysis. The crystal structure was elucidated by single-crystal X-ray diffraction. The 3-benzy1-1,3-diazaspiro[4.41nonane-2,4-dione crystallizes in triclinic P-1 space group, with two crystallographically independent molecules in the asymmetric unit. Cyclopentane ring adopts an envelope conformation. A three-dimensional crystal packing is governed by hydrogen N-H center dot center dot center dot O bonds, numerous C-H center dot center dot center dot O/N and C-H center dot center dot center dot pi interactions between neighboring molecules. Density functional theory (DFT) calculations with B3LYP and M06-2X methods using 6-311++G(d,p) basis set were performed to provide structural and spectroscopic information. Comparisons between experimental and calculated UV-Vis spectral properties suggest that the monomeric form of the investigated spirohydantoins is dominant in all used solvents. The effects of substituents on the absorption spectra of spirohydantoins are interpreted by correlation of absorption frequencies with Hammett equation. The lipophilicities of the investigated molecules were estimated by calculation of their log P values. Some of the spirohydantoins synthesized in this work, exhibit the lipophilicities comparable to the standard medicine anticonvulsant drug Phenytoin. The results obtained in this investigation afford guidelines for the preparation of new derivatives of spirohydantoin as potential anticonvulsant agents and for better understanding the structure-activity relationship.

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 a single crystal X-ray diffraction method. These compounds have multiple functional groups, which allow greater competition and/ or cooperation among the different intermolecular interactions in the formation of their crystal structures. The molecules are linked together by paired N-H... O hydrogen bonds in R22(8) rings, while the CH. 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 cyclohexyl 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 the 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 an emphasis on the X. p interactions. The lattice energies of all these crystal structures, as well as the 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 the relationship between the molecular interactions and crystal structures of the hydantoin derivatives. This is the peer-reviewed version of the following article: Crystengcomm, 2017, 19, 3, 469-483 [https://dx.doi.org/10.1039/C6CE02210C] [http://cer.ihtm.bg.ac.rs/handle/123456789/2204]