Sinteza i karakterizacija nekih metal(II) i metal(III) kompleksa sa diaminopolikarboksilatnim ligandima

U prvom delu ove doktorske disertacije, na osnovu rezultata rendgenske strukturne analize, opisana je kristalna struktura {[Sr2(1,3-pdta)(H2O)6].H2O}n kompleksa. Nađeno je da se u koordinacionoj sferi svakog Sr(II) jona, pored četiri molekula vode, nalaze jedan atom azota i četiri atoma kiseonika karboksilnih grupa koje potiču iz 1,3-propandiamin-N,N,N’,N’-tetraacetato liganda (1,3-pdta). Dva Sr(II) jona u {[Sr2(1,3-pdta)(H2O)6].H2O}n kompleksu su međusobno povezani preko diaminskog lanca 1,3-pdta liganda. Pored toga, svaki Sr(II) jon je mostno povezan preko dva karboksilna kiseonikova atoma i molekula vode sa dva susedna Sr(II) jona. Na bazi rezultata difrakcije rendgenskih zraka sa prahova i rezultata IR spektroskopije za različite M(II)-1,3-pdta komplekse, ispitivan je način koordinacije 1,3-pdta liganda u zavisnosti od veličine centralnih jona metala, kao i tip kompleksa koji pri tome nastaje. Rezultati ovih ispitivanja su objavljeni u radu: U. Rychlewska, B. Warżajtis, D. D. Radanović, N. S. Drašković, I. M. Stanojević and M. I. Djuran, Polyhedron, 30 (2011) 983-989. U drugom delu disertacije opisana je sinteza i spektroskopska (UV-Vis i IR spektri) karakterizacija kompleksa nikla(II) i bakra(II) sa novim heksadentatnim (±)-1,3-pentandiamin-N,N,N’,N’-tetraacetato (1,3-pndta) i pentadentatnim (±)-1,3-pentandiamin-N,N,N’-triacetato (1,3-pnd3a) ligandima. Ovi ligandi su strukturno slični sa ranije opisanim heksadentatnim 1,3-propandiamin-N,N,N’,N’- tetraacetato (1,3-pdta) i pentadentatnim 1,3-propandiamin-N,N,N’-triacetato (1,3-pd3a) ligandima. Rezultati rendgenske strukturne analize dobijeni za oktaedarski Mg[Ni(1,3-pndta)]10H2O kompleks ukazuju da prisustvo etil- supstituenta na α-ugljenikovom atomu doprinosi stvaranju novog hiralnog centra, što ima za posledicu građenje izomera (ΔΛΔ (R) i ΛΔΛ (S)) koji se razlikuju u konfiguraciji ovog centra (R ili S). Nađeno je da δ uvijena forma leđnog diaminskog prstena uslovljava Λ konfiguraciju, dok je u slučaju λ uvijene forme ovog prstena potvrđena Δ konfiguracija [Ni(1,3-pndta)]2- kompleksa. U slučaju stereoizomera ΔΛΔ (R) i ΛΔΛ (S) nađeno je da etil grupa zauzima ekvatorijalni položaj na centralnom šestočlanom diaminskom prstenu. Elektronski apsorpcioni i infra-crveni spektri Ni(II) i Cu(II) kompleksa sa heksadentatno koordinovanim 1,3-pndta ligandom (Mg[Ni(1,3-pndta)]10H2O i Mg[Cu(1,3- pndta)].7H2O) i pentadentatno koordinovanim 1,3-pnd3a ligandom (Mg[Ni2(1,3- pnd3a)2]8H2O i Mg[Cu2(1,3-pnd3a)2].7H2O) su poređeni sa odgovarajućim spektrima analognih Mg[Ni(1,3-pdta)].8H2O i Mg[Cu(1,3-pdta)].8H2O i Mg[Cu2(1,3-pd3a)2].7H2O kompleksa poznatih kristalnih struktura. Rezultati ovih ispitivanja su objavljeni u radu: N. S. Drašković, D. D. Radanović, U. Rychlewska, B. Warżajtis, I. M. Stanojević and M. I. Djuran, Polyhedron, 43 (2012) 185-193. U trećem delu disertacije opisana je sinteza i karakterizacija serije hrom(III) kompleksa sa heksadentatno koordinovanim ()-1,3-pentandiamin- N,N,N,N-tetraacetato (1,3-pndta) ligandom i Na+, K+ i Ca2+ jonima kao kontra- katjonima. Struktura ovih kompleksa je potvrđena na osnovu rendgenske strukturne analize. Ispitivan je uticaj kontra-katjona i supstituisanog diaminskog prstena na samoorganizaciju molekula i stepen hidratacije molekula u kristalima. Različiti načini vezivanja karboksilnih grupa za jone metala uslovljavaju formiranje 3D, 2D i 1D polimernih struktura. Elektronski apsorpcioni i 1H NMR spektri [Cr(1,3-pndta)]- kompleksa su diskutovani u odnosu na [Cr(1,3-pdta)]- komplekse poznatih kristalnih struktura. Rezultati ovih ispitivanja su objavljeni u radu: B. Warżajtis, U. Rychlewska, D. D. Radanović, I. M. Stanojević, N. S. Drašković, N. S. Radulović and M. I. Djuran, Polyhedron, 67 (2014) 270-278.The first part of this thesis deals with synthesis and the X-ray characterization of the missing homonuclear s-block metal complex {[Sr2(1,3-pdta)(H2O)6].H2O}n. In the title compound, the hexadentate 1,3-propanediaminetetraacetate (1,3-pdta) ligand joins to two Sr(II) centers via the diamine chain. Moreover, each Sr(II) is bridged through two carboxylate O atoms and a water molecule to two neighboring Sr(II) ions. The coordination sphere around each Sr(II) ion consists of one diamine nitrogen, four carboxylate oxygens and four water molecules. Comparison with the previously reported M(II)-1,3-pdta complexes reveals that increasing of the ion size results in incorporation of water molecules into its first coordination sphere and consequent increase of the C.N. from six to seven or eight while keeping the hexadentate coordination mode of the ligand. Further increase of the metal ion size leads to the loss of the chelating properties of the diamine and formation of bis-tridentate complex. Associated with it is the change in the binding mode of the carboxylate groups. This forms the basis for classification of the divalent metal 1,3-pdta complexes into five distinct structural classes. Additionally, in the present study the X-ray powder diffraction and IR spectroscopy were used for distinguishing different structural types of M(II)-1,3-pdta complexes including Ba[Ba(1,3- pdta)]·2H2O which has been used for their preparation. The above mentioned results have been published in the paper: U. Rychlewska, B. Warżajtis, D. D. Radanović, N. S. Drašković, I. M. Stanojević and M. I. Djuran, Polyhedron, 30 (2011) 983-989. In the second part of this thesis, structural variations modulated by ethyl side group have been analyzed for nickel(II) and copper(II) complexes with (±)-1,3- Summary IV pentanediamine-N,N,N’,N’-tetraacetate ligand (1,3-pndta) and its pentadentate derivative (±)-1,3-pentanediamine-N,N,N’-triaacetate (1,3-pnd3a). X-ray results obtained for the octahedral 1,3-pndta-Ni(II) complex indicate the distinct correlation of the central chirality of the metal with the chirality at the diamine α-carbon, which leads to the formation of a racemic mixture of ΔΛΔ(R) and ΛΔΛ(S) enantiomeric anionic complexes, where the R and S labels designate the absolute configuration at the ligand (ethyl-substituted) stereogenic center. These stereoisomers are those required to maintain an equatorial ethyl group on the central six-membered chelate ring, whose conformation is λ twist-boat for the ΔΛΔ isomer and δ twist-boat for the ΛΔΛ isomer. Ethyl group discernibly affects the variation of the Ni–N and Ni–O bond lengths compared to the analogous complex lacking the substitution of one of the diastereotopic diamine CH2 hydrogens and functions as steric bulkiness which hampers an efficient and of high symmetry packing, observed in the crystals of the parent complex. The infrared and electronic absorption spectra of hexadentate Mg[Ni(1,3- pndta)]10H2O and Mg[Cu(1,3-pndta)].7H2O, and pentadentate Mg[Ni2(1,3- pnd3a)2].8H2O and Mg[Cu2(1,3-pnd3a)2].7H2O complexes are presented and discussed in comparison with those of the analogous Mg[Ni(1,3-pdta)].8H2O, Mg[Cu(1,3-pdta)].8H2O and Mg[Cu2(1,3-pd3a)2].7H2O complexes of known crystal structures. The obtained results from this investigation has been published in: N. S. Drašković, D. D. Radanović, U. Rychlewska, B. Warżajtis, I. M. Stanojević and M. I. Djuran, Polyhedron, 43 (2012) 185-193. Finally in this thesis, series of Na+, K+ and Ca2+ salts of chromium(III) complexes with the hexadentate ()-1,3-pentanediamine-N,N,N,N-tetraacetate (1,3-pndta) ligand was evaluated. The extent of distortion exhibited in the geometry of these octahedral complexes was computed and related to the configuration at the metal center and the ligand stereogenic center. The materials have been used to investigate the effect of the counter ion and the diamine ring substitution on the self organization and degree of hydration of these molecules in crystals. Various modes of carboxylate binding to metal atoms have been related to the formation of 3D, 2D and 1D polymeric structures. The electronic absorption and 1H NMR spectra of 1,3-pndta-Cr(III) complexes are discussed in relation to those of 1,3-pdta-Cr(III) complex (1,3-propanediamine-N,N,N,N-tetraacetate ion) of known structure. The results of this investigation has been published in: B. Warżajtis, U. Rychlewska, D. D. Radanović, I. M. Stanojević, N. S. Drašković, N. S. Radulović and M. I. Djuran, Polyhedron, 67 (2014) 270-278

Early effects of ionizing ir-radiation on the ecto- 5'nucleotidase activity in rat brain during postnatal development

In the present study, early effects of low (50 cGy) and therapeutic dose (2 Gy) of ionizing γ-irradiation on ecto-5’nucleotidase activity in rat brain neuronal cells during postnatal development were studied. Ecto-5’-nucleotidase is the major enzyme that hydrolyzes extracellular AMP and is responsible for the formation of the P1 receptor agonist-adenosine. It was shown that the levels of AMP hydrolyses by the enzyme were not affected by irradiation in the rats during first 4 postnatal weeks. A both low- and therapeutic dose significantly decreased hydrolyses of extracellular AMP in pubertal and adult rats by 10-14%. These findings indicate that low dose exerts the same effects on ecto-5'nucleotidase activity as therapeutic one in first hour after irradiation. Another findings is that in early postnatal development, brain ecto-5'nucleotidase was resistant to irradiation damage.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Ionizing irradiation affect extracellular nucleotide hydrolysis in brain of rats in different stages of development: i 15-day-old rats

Ionizing radiation affects plasma membrane functions mediated through transmembrane proteins including enzymes. Plasma membrane surface-located enzyme chain of ecto-nucleotide triphospho diphosphohydrolases (NTPDases) are involved in termination of cell purinergic signalization by hydrolysing extracellular adenosine tri- and di-phosphate (ATP and ADP). In the present study, effects of low (50 cGy) and therapeutic (2 Gy) dose of ionizing γ-irradiation on NTPDase activity in early postnatal rat brain neuronal cells were studied. Both low- and therapeutic doses significantly decreased hydrolyze of extracellular ATP (by 11% and 30%) and ADP (18% and 46%) in postnatal rats. These findings indicate that gammaradiation inhibits the enzyme activity in dose-dependent manner. This decreasing NTPDase activity 24h after whole body irradiation may lead to neuronal cell function disturbance, even cell death.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Ionizing irradiation affect extracellular nucleotide hydrolysis in brain of rats in different stages of development: ii 30-day-old rats

The effect of acute gamma irradiation (IR) on enzyme activity of rat brain Ecto-Nucleotide Diphosphohydrolase (E-NTPDase), in presence of adenosine triand diphophashates (ATP and ADP) and divalent cations (Ca2+ and Mg2+), has been investigated. The aim of research was to study the influence of low (50 cGy) and therapeutic (2Gy) doses of whole-body irradiation on rat brain E-NTPDase enzyme activity 24h after treatment in prepubertal and adult rats. Our results suggest that whole-body irradiation could induce modulation of neural activity in rat brain, especially in young rats.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Low-dose ionizing irradiation affects ntpdase activity in neuoronal cells of young female rats

In the present study, time-dependent effects of low-dose ionizing irradiation on membrane-bound enzyme activity in neuronal cell endings of young female rat brains were sudied. The ecto-adenosine triphospho diphosphohydrolases (NTPDases) hydrolyse the extracellular nucleotide di- and tri- phosphates (ADP and ATP) in the presence of divalent cations (Ca2+ and Mg2+). The influence of whole-body irradiation on membrane enzymes ATP and ADP hydrolysing activity were monitored 1, 24 and 72 h after irradiation. Animals were divided into three groups: non-treated, under physiological conditions (C), immobilized and whole body irradiated with 50 cGy by γ-rays (R) and immobilized non-irradiated (I) animals. It was shown that the levels of ATP and ADP hydrolyses were not affected within 72h after immobilisation. Lowdose irradiation significantly decreased hydrolyses of extracellular ATP as early as 1h after irradiation. ADP hydrolyses within 72 h and ATP hydrolysis after 24 h were not altered.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Finite element model for stress analysis and nonlinear contact analysis of helical gears

Određivanje naponskog i deformacionog stanja na bokovima i u podnožju zubaca jedan je od osnovnih zadataka u toku proračuna opterećenja i provere nosivosti zupčanika. U ovom radu opisan je postupak razvijanja modela konačnih elemenata za istovremeno praćenje naponskog i deformacionog stanja bokova zubaca, podnožja zubaca i segmanata zupčanika sa kosim zupcima u toku sprezanja jednog para zubaca. Takođe, opisano je i simuliranje kontaktnih uslova kod evolventnih zupčanika sa kosim zupcima metodom konačnih elemenata (MKE). Izvršena je odgovarajuća analiza za izbor modela spregnutih zupčanika koji je istovremeno dovoljno ekonomičan i dovoljno geometrijski precizan. Razvijen je poseban algoritam za crtanje evolventnog profila zubaca. Ovaj algoritam ugrađen je u postojeći MKE softver i na taj način je obezbeđeno crtanje realne geometrije bokova zubaca u kontaktu. Takođe, izvršen je i izbor optimalne gustine mreže konačnih elemenata. Opisani modeli konačnih elemenata razvijeni su za jedan konkretan par zupčanika sa kosim zupcima. Dobijeni numerički rezultati pogodni su za praćenje promene deformacionog i naponskog stanja u toku perioda sprezanja para zubaca. .One of the main goals during load calculations and load capacity check for gears is determination of deformation and stress state in teeth contact zones and teeth fillets. This paper describes development of the finite element model for simultaneously monitoring the deformation and stress state of teeth flanks, teeth fillets and parts of helical gears during the tooth pair meshing period. The paper also describes the Finite Element Method simulation of contact conditions for helical gears teeth with an involute profile. A suitable analysis is performed in order to select a meshed gears model which is sufficiently economic and in same tame sufficiently geometrically accurate. The special algorithm for the tooth involute profile drawing is developed and built in a currently available software for Finite Element Analysis to assure drawing of real flanks contact geometry. The optimal mesh size level is chosen, too. The described finite element models are made for the particular helical gear pair. The obtained numerical results are suitable for tracking deformation and stress variables during the tooth pair meshing period.

The use of bacterial indole-3-acetic acid (IAA) for reduce of chemical fertilizers doses

The standard technology of seed processing uses mainly chemical products. Recent researches showed that toxic materials from chemical fertilizers can be harmful to humans, animals and the environment. Currently the attention of researches is shifting away from chemical fertlizers and toward alternative that consumers perceive to be natural, Plant Growth Promoting bacteria (PGP). PGP bacteria could be a way to reduce chemical fertilizer doses. This was the reason to test the ability of Bacillus megaterium, Azotobacter chroococcum to produce hormone auxin (IAA). Bacterial strains were identified by PCR amplification and sequencing of the 16S rRNA gene. Indole-3-acetic acid (IAA) was detected and quantified by MRM experiment. This study conducted that maize seed inoculation with IAA from species mentioned above showed positive effects. They had statistically significantly higher root and steam height compared to control seedlings. Bacterial strains tested in this study may be recommended as PGP (Plant Growth Promoting) bacteria, due to their positive effects and eventually can be used to reduce chemical fertilizers doses

Copper(II) complexes with different diamines as inhibitors of bacterial quorum sensing activity

Three copper(II) complexes, trans-[Cu(1,3-pd)(2)Cl-2]center dot H2O (Cu1; 1,3-pd is 1,3-propanediamine), trans-[Cu(2,2-diMe-1,3-pd)(2)Cl-2] (Cu2; 2,2-diMe-1,3-pd is 2,2-dimethyl-1,3-propanediamine) and trans-[Cu(1,3-pnd)(2)Cl-2]center dot H2O (Cu3; 1,3-pnd is (+/-)-1,3-pentanediamine), were synthesized and structurally characterized by elemental microanalyses, IR, electronic absorption and reflectance spectroscopy and molar conductivity measurements. The antimicrobial efficiency of the complexes against four clinically relevant microorganisms and their antiproliferative effect on the normal human lung fibroblast cell line MRC-5 were evaluated. Since in many bacteria, pathogenicity is regulated by an intercellular communication process called quorum sensing (QS), the effect of the copper(II) complexes Cu1-3 on bacterial QS was examined. The obtained results showed that these complexes inhibited violacein production in Chromobacterium violaceum CV026, indicating their anti-QS activity via the homoserine lactone (HSL) pathway. Two biosensor strains were used to determine which pathway, C4-HSL (N-butanoylhomoserine lactone) or 3OC12-HSL (N-(3-oxododecanoyl) homoserine lactone), was affected by the copper(II) complexes. The biological activities of the copper(II) complexes were compared with those for the nickel(II) complexes of the general formula trans-[Ni(L)(2)(H2O)(2)]Cl-2 (L = 1,3-pd, 2,2-diMe-1,3-pd and 1,3-pnd)

POSSIBLE WAYS OF ORGANIZING FOREIGN LANGUAGE TEACHING USING LANGUAGE TRANSFER

The main focus of this paper is to examine the role of English as the first foreign language (FL1) in learning German as a second foreign language (FL2) at the university level. The results will provide insight into the possibilities of improving foreign language teaching at tertiary level. More specifically, the aim of this research is to find out to what extent Serbian students, whose mother tongue is Serbian, rely on their knowledge of English as the FL1 while learning German as the FL2. The research was done with first year students (N=140) from the departments class teacher, pre-school teacher and boarding school teacher at the Faculty of Education in Jagodina. A comparative study of positive and negative transfer of English in the process of learning German will be presented in the paper. The paper will outline specific strategies that could be of great help in learning the foreign language, as well as the ideas for the higher education quality improvement. In addition, the authors will point out different issues of cross-linguistic influence in language learning and suggest some ideas for practice improvement in this area.Publishe

Tailoring Atomoxetine Release Rate from DLP 3D-Printed Tablets Using Artificial Neural Networks: Influence of Tablet Thickness and Drug Loading

Various three-dimensional printing (3DP) technologies have been investigated so far in relation to their potential to produce customizable medicines and medical devices. The aim of this study was to examine the possibility of tailoring drug release rates from immediate to prolonged release by varying the tablet thickness and the drug loading, as well as to develop artificial neural network (ANN) predictive models for atomoxetine (ATH) release rate from DLP 3D-printed tablets. Photoreactive mixtures were comprised of poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) 400 in a constant ratio of 3:1, water, photoinitiator and ATH as a model drug whose content was varied from 5% to 20% (w/w). Designed 3D models of cylindrical shape tablets were of constant diameter, but different thickness. A series of tablets with doses ranging from 2.06 mg to 37.48 mg, exhibiting immediate- and modified-release profiles were successfully fabricated, confirming the potential of this technology in manufacturing dosage forms on demand, with the possibility to adjust the dose and release behavior by varying drug loading and dimensions of tablets. DSC (differential scanning calorimetry), XRPD (X-ray powder diffraction) and microscopic analysis showed that ATH remained in a crystalline form in tablets, while FTIR spectroscopy confirmed that no interactions occurred between ATH and polymers