Theoretical investigation of structural and electronic influences on the magnetic properties of transition metal complexes

U okviru ove doktorske disertacije analizirane su magnetne osobine mononuklearnih i binuklearnih kompleksa prve serije prelaznih metala LF-DFT i DFT metodama. Poznavanje magnetnih osobina kompleksnih jedinjenja omogućuje predviđanje i dizajniranje molekula sa traženim svojstvima koja se mogu iskoristiti za skladištenje informacija na kvantnom nivou. Molekulski magneti, tj. mononuklearni sistemi sa velikom vrednošću magnetne anizotropije nalaze se u žiži interesovanja s obzirom na njihovu potencijalnu primenu u kvantnom računarstvu. Analizom faktora koji određuju magnetna svojstva u mononuklearnim kompleksima pronašli smo već sintetisani kompleksni jon [NiCl3(Hdabco)2]+ (dabco=1,4-diazabicyclo[2.2.2]-octane) sa veoma velikom vrednosti aksijalnog parametra cepanja, D. Osnovni uzrok ovako velikih vrednosti predstavlja interakcija između dx 2 -y 2 i dxy Magnetna kuplovanja između paramagnetnih centara u binuklearnim kompleksima analizirana su BS (Broken Symmetry) DFT metodom. U svim slučajevima jačina magnetnih interakcija zavisi od elektronske strukture metala, kao i od prirode i orijentacije mostnih liganada. orbitala. Efekti Jahn-Teller-ove distorzije, koji deluju nasuprot spin-orbitalnom kuplovanju, umanjeni su prisustvom voluminoznih dabco liganada, koji se nalaze u aksijalnom položaju. Usled sternog zaklanjanja aksijalnih liganada atomi hlora u ekvatorijalnoj ravni, slabo se pomeraju jedan u odnosu na drugi. Distorzije u regiji mosta dovode do znatnog slabljenja antiferomagnetnih interakcija...Magnetic properties of mononuclear and binuclear transition metal complexes were analyzed by the means of LF-DFT and DFT methods. The understanding of magnetic properties of metal complexes allow us to predict and design molecules with required characteristics, which can be used to store the informations on quantum level. Molecular magnets, i.e. mononuclear systems with large magnetic anisotropy value are in the focus of interest due to their potential applications in quantum computing. Through the analysis of the factors that determine the magnetic properties of mononuclear complexes, we found complex ion [NiCl3(Hdabco)2]+ (dabco=1,4-diazabicyclo[2.2.2]- octane) with very high values of axial splitting parameter, D. The main cause for such a large value lies in interactions between dx 2 -y 2 and dxy Magnetic couplings between paramagnetic centers in binuclear complexes were analyzed using Broken Symmetry (BS) DFT method. In all investigated cases the strength of magnetic interactions depends upon the electronic structure and the structure of bridging ligands. orbitals. The effects of Jahn-Teller distortion, which act opposed to spin-orbit coupling, are suppressed by the presence of voluminous dabco ligands, which are placed in axial position. Due to the steric hindrance of axial ligands, the chlorine atoms in equatorial plane can not move easily. The distortions in the bridge region lead to a significant weakening of antiferromagnetic interactions..

Supplementary data for article: Perić, M.; Niketic, S.; Zlatar, M.; Gruden-Pavlović, M.; Grubišić, S. DFT and MM Description of the Structure and Magnetic Properties of Manganese Complexes with X-Phenylcyanamido Bridging Ligand. Monatshefte Fur Chemie 2011, 142 (6), 585–592. https://doi.org/10.1007/s00706-011-0502-x

Supplementary material for: [https://doi.org/10.1007/s00706-011-0502-x]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1340

Supplementary data for article: Perić, M.; Niketic, S.; Zlatar, M.; Gruden-Pavlović, M.; Grubišić, S. DFT and MM Description of the Structure and Magnetic Properties of Manganese Complexes with X-Phenylcyanamido Bridging Ligand. Monatshefte Fur Chemie 2011, 142 (6), 585–592. https://doi.org/10.1007/s00706-011-0502-x

Supplementary material for: [https://doi.org/10.1007/s00706-011-0502-x]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1340

Estimation of measurement uncertainty in measuring radiopharmaceutical activity in dose calibrator

Doze kalibrator je jedan od osnovnih uređaja u nuklearnoj medicini, koji se koristi za merenje aktivnosti (doza) radiofarmaceutika koji se daju pacijentima bilo u dijagnostičke ili u terapijske svrhe. Aktivnosti gama i beta emitera različitih energija moraju da budu izmerene što tačnije da bi izlaganja ljudi (pacijenata) jonizujućem zračenju bila svedena na najmanji mogući nivo, a da se dobiju klinički značajni rezultati. Početna tačnost kalibratora (nesigurnost 5% ili manje) može se vremenom menjati kao rezultat promene pritiska u jonizacionoj komori ili električnog drifta. Zbog toga kontrola kvaliteta doze kalibratora treba da se sprovodi rutinski kako bi se osigurala tačnost i sledljivost merenja.U radu su prikazani rezultati procene nesigurnostipri merenjima aktivnosti radiofarmaceutika u doze kalibratoru u Laboratoriji za radioizotope. Komponente nesigurnosti, koje su važne za ova merenja, identifikuju se i uzimaju u obzir prilikom procene merne nesigurnosti. Razumevanje izvora nesigurnosti i korišćenje odgovarajućih korekcionih faktora mogu minimizirati netačna merenja.A dose calibrator is an essential device in a nuclear medicine, utilized for measurement the activity of radiopharmaceuticals administered to patients both for diagnostic and therapeutic purposes. It has to measurethe radioactivity of gamma and beta with different energies precisely for high quality imaging and for applying the right amount of radiation to treat disease. Initial accuracy (uncertainty 5% or less) may change with time as a result of changing pressureof the chamber gas and slow electrical drift. The quality controls should be undertaken on a routine basis to ensure the accuracy and traceability of measurements of the activities of radiopharmaceuticals.The paper presents the results of estimation of uncertainty in the measurement of the activity in the dose calibrator in the Laboratory for radioisotopes. The uncertainty components, that are important for these measurements, are identified and taken into account while estimating the uncertainty of measurement. Understanding the source of uncertainty and using appropriate techniques can minimize inaccurate measurements.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј

Estimating CDKN2A mutation carrier probability among global familial melanoma cases using GenoMELPREDICT

Background: Although rare in the general population, highly penetrant germline mutations in CDKN2A are responsible for 5%-40% of melanoma cases reported in melanoma-prone families. We sought to determine whether MELPREDICT was generalizable to a global series of families with melanoma and whether performance improvements can be achieved. Methods: In total, 2116 familial melanoma cases were ascertained by the international GenoMEL Consortium. We recapitulated the MELPREDICT model within our data (GenoMELPREDICT) to assess performance improvements by adding phenotypic risk factors and history of pancreatic cancer. We report areas under the curve (AUC) with 95% confidence intervals (CIs) along with net reclassification indices (NRIs) as performance metrics. Results: MELPREDICT performed well (AUC 0.752, 95% CI 0.730-0.775), and GenoMELPREDICT performance was similar (AUC 0.748, 95% CI 0.726-0.771). Adding a reported history of pancreatic cancer yielded discriminatory improvement (P < .0001) in GenoMELPREDICT (AUC 0.772, 95% CI 0.750-0.793, NRI 0.40). Including phenotypic risk factors did not improve performance. Conclusion: The MELPREDICT model functioned well in a global data set of familial melanoma cases. Adding pancreatic cancer history improved model prediction. GenoMELPREDICT is a simple tool for predicting CDKN2A mutational status among melanoma patients from melanoma-prone families and can aid in directing these patients to receive genetic testing or cancer risk counseling

DFT and MM description of the structure and magnetic properties of manganese complexes with X-phenylcyanamido bridging ligand

Magnetic properties of the complexes [Mn(3-Clpcyd)(H(2)O)-(phen)(2)](+), [{Mn(3-Fpcyd)(MeOH)(phen)}(2)(mu-3-Fpcyd)(2)], [{Mn(3-Fpcyd)(EtOH)(phen)}(2)(mu-3-Fpcyd)(2)], [{Mn(3-Clpcyd)(MeOH)(phen)}(2)(mu-3-Clpcyd)(2)], and [{Mn(4-Clpcyd)(EtOH)(phen)}(2)(mu-4-Clpcyd)(2)] (where Xpcyd = halogeno-phenylcyanamido; phen = 1,10-phenanthroline) have been explored by means of density functional theory (DFT). Exchange coupling constants were calculated from the energy differences between the high-spin and broken-symmetry states. Very good agreement between theoretical and experimental data was achieved. The g-tensor calculations were performed employing the coupled perturbed Kohn-Sham equations. Molecular mechanics calculations have been performed to elucidate structural features in the five complexes. Finally, the reliability of the molecular mechanics results was confirmed by comparing the magnetic couplings calculated on optimized structures with experimental data.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3609

External magnetic field influence on magnetite and cobalt-ferrite nano-particles in ferrofluid

Using simple optical measurements, the selective spectral behavior of suspended nano-particles of magnetite (Fe3O4) and cobalt-ferrite (CoFe2O4) coated with starch, was observed through switching on/off of external magnetic field. The field strength was varied in the interval 30–300 mT. In these transient regimes, the unexpected and unusually large changes of transmitted light occur. An explanation is suggested, within the model based on ordering of magnetic moments of nano-particles along the lines of magnetic field into magnetic chains and organization of magnetic chains into spatial structure—a quasi-lattice. This fact indicates the possibility of more efficient local heating of nano-particles in the fast changing magnetic field; for instance when taking magnetic nano-particles for therapeutic purposes

Molecular mechanics description of the stabilized effects in (ethylenediamine-N,N '-diacetato)chromate(III) dinuclear complex bridged by pyrazole-3,5-dicarboxylate: DFT calculations of magnetic properties

The mononuclear chromium(III) complex containing quadridentate ligand ethylenediamine-N,N'-diacetate (edda) and the corresponding dinuclear complex bridged by pyrazole-3,5-dicarboxylate (pzdc) are investigated by molecular mechanics calculations. Conformational analysis has been performed using the consistent force field (CFF) method, with the parameters developed previously for edta-type complexes and supplemented with new parameters for dinuclear system. These calculations indicated that many properties of [Cr-2(edda)(2)(mu-pzdc)](-) system can be explained by steric effects. Density functional theory (DFT) was applied to describe the magnetic couplings in [Cr-2(edda)(2)(mu-pzdc)](-). (c) 2008 Elsevier B.V. All rights reserved

On the driving forces behind the change of reduction potentials and the prediction of redox properties through analysis of EPR hyperfine couplings in VO(acac)2pyr and VO(acac)2 imidazole complexes. A DFT study

The use of vanadium complexes for potential applications in medicine largely depends on the structural properties of the complex itself, as well as on the electronic configuration of the metal and its oxidation state. When the vanadium complex binds to biomolecules or by binding solvent molecules to the complex, there is a change in the structure but also a change in the redox properties of the complex. Using theoretical methods, especially Density Functional theory (DFT), it is possible to determine which factors influence changes in the redox properties of the complex. Furthermore, by calculating the Electron Paramagnetic Resonance (EPR) constants of hyperfine coupling, it is possible to obtain not only data on the electronic configuration, but also to predict changes in redox properties upon changes in the structure of the complex. DFT results show that the binding of pyridine or imidazole to the VO(acac)2 complex leads to a lowering of the redox potential. The largest changes in the redox potential were observed in the case when the incoming ligand binds in a cis position relative to the V==O bond

Estimation of measurement uncertainty in measuring radiopharmaceutical activity in dose calibrator

Doze kalibrator je jedan od osnovnih uređaja u nuklearnoj medicini, koji se koristi za merenje aktivnosti (doza) radiofarmaceutika koji se daju pacijentima bilo u dijagnostičke ili u terapijske svrhe. Aktivnosti gama i beta emitera različitih energija moraju da budu izmerene što tačnije da bi izlaganja ljudi (pacijenata) jonizujućem zračenju bila svedena na najmanji mogući nivo, a da se dobiju klinički značajni rezultati. Početna tačnost kalibratora (nesigurnost 5% ili manje) može se vremenom menjati kao rezultat promene pritiska u jonizacionoj komori ili električnog drifta. Zbog toga kontrola kvaliteta doze kalibratora treba da se sprovodi rutinski kako bi se osigurala tačnost i sledljivost merenja.U radu su prikazani rezultati procene nesigurnostipri merenjima aktivnosti radiofarmaceutika u doze kalibratoru u Laboratoriji za radioizotope. Komponente nesigurnosti, koje su važne za ova merenja, identifikuju se i uzimaju u obzir prilikom procene merne nesigurnosti. Razumevanje izvora nesigurnosti i korišćenje odgovarajućih korekcionih faktora mogu minimizirati netačna merenja.A dose calibrator is an essential device in a nuclear medicine, utilized for measurement the activity of radiopharmaceuticals administered to patients both for diagnostic and therapeutic purposes. It has to measurethe radioactivity of gamma and beta with different energies precisely for high quality imaging and for applying the right amount of radiation to treat disease. Initial accuracy (uncertainty 5% or less) may change with time as a result of changing pressureof the chamber gas and slow electrical drift. The quality controls should be undertaken on a routine basis to ensure the accuracy and traceability of measurements of the activities of radiopharmaceuticals.The paper presents the results of estimation of uncertainty in the measurement of the activity in the dose calibrator in the Laboratory for radioisotopes. The uncertainty components, that are important for these measurements, are identified and taken into account while estimating the uncertainty of measurement. Understanding the source of uncertainty and using appropriate techniques can minimize inaccurate measurements.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј