Vodonična veza u push-pull 5-supstituisanim 2-alkiliden-4-oksotiazolidinima: 1H-NMR spektroskopsko proučavanje

Application of dynamic H-1-NMR spectroscopy added to the understanding of the hydrogen bonds existing in the structurally related 5-substituted-2-alklidene-4-oxothiazolidines in polar and apolar solvents. The equilibrated mixtures of these topical push-pull alkenes in CDCl3 consist of the intramolecularly H-bonded (E)-isomer and intermolecularly H-bonded (Z)-isomer in varying proportions which depend on the solvent polarity. For the representative of the series. (Z)-2-(5-ethoxycarbonylmethyl-4-oxothiazolidin-2-ylidene)-1-phenylethanone, a concentration effect on the degree of intermolecular hydrogen bonding in apolar CDCl3 has been studied.Primenom dinamičke 1H-NMR spektroskopije došlo se do boljeg razumevanja o vrsti vodoničnih veza koje postoje u strukturno sličnim 5-supstituisanim 2-alkiliden-4-oksotiazolidinima u polarnim i apolarnim rastvaračima. Uravnotežene smese ovih tipičnih push-pull alkena u CDCl3 sadrže (E)-izomer vezan intramolekulskom vodoničnom vezom kao i intermolekulski vodoničnom vezom vezan (Z)-izomer u različitim odnosima, koji zavise od polarnosti rastvarača. U slučaju tipičnog predstavnika serije (Z)-2-(5-etoksikarbonilmetil-4-oksotiazolidin- 2-iliden)-1-feniletanona uticaj koncentracije na stepen stvaranja intermolekulske vodonične veze u apolarnom CDCl3 je takođe proučavan

Thionation of N-Methyl- and N-Unsubstituted Thiazolidine Enaminones

The potential of the directional non-bonded 1,5-type S···O interactions to initiate an incipient stage of an in situ rearrangement of N-unsubstituted thiazolidine enaminones to the functionalized 1,2-dithioles has been demonstrated. Spectral characteristics, as well as an X-ray structural analysis of the selected rearranged product, indicate that a dynamic interconversion occurs in a solution between the 1,2-dithiole and 3,3aλ⁴,4-trithia-1-azapentalene bicylic form. The lack of the rearrangement in the case of the N-methyl substituted enaminone precursor is attributed to an unfavorable methyl migration in the last reaction step

Thermal solid-state Z/E isomerization of 2-alkylidene-4-oxothiazolidines: effects of non-covalent interactions

Configurational isomerization of stereo-defined 5-substituted and un-substituted 2-alkylidene-4-oxothiazolidines (1) in the solid state, giving the Z/E mixtures in various ratios, was investigated by H-1-NMR spectroscopy, X-ray powder crystallography and differential scanning calorimetry (DSC). The Z/E composition can be rationalized in terms of non-covalent interactions, involving intermolecular and intramolccular hydrogen bonding and directional non-bonded 1,5-type S center dot center dot center dot O interactions. X-Ray powder crystallography, using selected crystalline (Z)-4-oxothiazolidine substrate, revealed transformation to the amorphous state during the irreversible Z - gt E process. A correlation between previous results on the Z/E isomerization in solution and now in the solid state was established

Supplementary data for the article: Rašović, A.; Blagojević, V.; Baranac-Stojanović, M.; Kleinpeter, E.; Marković, R.; Minić, D. M. Quantification of the Push-Pull Effect in 2-Alkylidene-4-Oxothiazolidines by Using NMR Spectral Data and Barriers to Rotation around the CC Bond. New Journal of Chemistry 2016, 40 (7), 6364–6373. https://doi.org/10.1039/c6nj00901h

Supplementary material for: [https://doi.org/10.1039/c6nj00901h]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2336

Supplementary data for article: Vukanović, S. B.; Tadić, V. M.; Blagojević, N.; Pešić, V. V.; Durdić, S.; Stanković, M.; Mutić, J. Element Accumulation Capacity of Vaccinium Myrtillus from Montenegro: Comparison of Element Contents in Water and Ethanol Extracts of Bilberry Plant Parts. Archives of Biological Sciences 2019, 71 (1), 145–157. https://doi.org/10.2298/ABS181004056B

Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3055

Element accumulation capacity of Vaccinium myrtillus from Montenegro: Comparison of element contents in water and ethanol extracts of bilberry plant parts

Bilberry (Vaccinium myrtillus L., Ericaceae) is a rich source of different mineral elements that are important as essential trace elements, or that can be potentially toxic, depending on their concentration. The contents of sixteen elements: the major (Al, Ca, Fe, K and Mg) and trace elements (As, Ba, Cd, Co, Cu, Cr, Mn, Ni, Pb, Sr and Zn) in roots, stems, leaves and fruits of bilberry and the corresponding soil substrate were determined in order to investigate element mobility and availability in soil. Soil was subjected to sequential extraction procedure as proposed by the Community Bureau of Reference in order to fractionate acid-soluble/exchangeable, reducible, oxidizable and residual fractions. Analysis of water and ethanol extracts of bilberry aerial parts revealed a significant transfer of elements during the extraction procedure, with corresponding extraction coefficient values of up to 95.12%. Results showed that bilberry fruits could serve as a good dietary source of essential elements for humans, especially Mn and Cu.Supplementary data: [http://cherry.chem.bg.ac.rs/handle/123456789/3057

Performance of a Large-Area GEM Detector Prototype for the Upgrade of the CMS Muon Endcap System

Gas Electron Multiplier (GEM) technology is being considered for the forward muon upgrade of the CMS experiment in Phase 2 of the CERN LHC. Its first implementation is planned for the GE1/1 system in the $1.5 < \mid\eta\mid < 2.2$ region of the muon endcap mainly to control muon level-1 trigger rates after the second long LHC shutdown. A GE1/1 triple-GEM detector is read out by 3,072 radial strips with 455 $\mu$rad pitch arranged in eight $\eta$-sectors. We assembled a full-size GE1/1 prototype of 1m length at Florida Tech and tested it in 20-120 GeV hadron beams at Fermilab using Ar/CO$_{2}$ 70:30 and the RD51 scalable readout system. Four small GEM detectors with 2-D readout and an average measured azimuthal resolution of 36 $\mu$rad provided precise reference tracks. Construction of this largest GEM detector built to-date is described. Strip cluster parameters, detection efficiency, and spatial resolution are studied with position and high voltage scans. The plateau detection efficiency is [97.1 $\pm$ 0.2 (stat)]\%. The azimuthal resolution is found to be [123.5 $\pm$ 1.6 (stat)] $\mu$rad when operating in the center of the efficiency plateau and using full pulse height information. The resolution can be slightly improved by $\sim$ 10 $\mu$rad when correcting for the bias due to discrete readout strips. The CMS upgrade design calls for readout electronics with binary hit output. When strip clusters are formed correspondingly without charge-weighting and with fixed hit thresholds, a position resolution of [136.8 $\pm$ 2.5 stat] $\mu$rad is measured, consistent with the expected resolution of strip-pitch/$\sqrt{12}$ = 131.3 $\mu$rad. Other $\eta$-sectors of the detector show similar response and performance.Comment: 8 pages, 32 figures, submitted to Proc. 2014 IEEE Nucl. Sci. Symposium, Seattle, WA, reference adde

Overview of large area triple-GEM detectors for the CMS forward muon upgrade

In order to cope with the harsh environment expected from the high luminosity LHC, the CMS forward muon system requires an upgrade. The two main challenges expected in this environment are an increase in the trigger rate and increased background radiation leading to a potential degradation of the particle ID performance. Additionally, upgrades to other subdetectors of CMS allow for extended coverage for particle tracking, and adding muon system coverage to this region will further enhance the performance of CMS

A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.Comment: 4 pages, 4 figures, presented by Luigi Benussi at MPGD 2015 (Trieste, Italy). arXiv admin note: text overlap with arXiv:1512.0848

Development and performance of Triple-GEM detectors for the upgrade of the muon system of the CMS experiment

The CMS Collaboration is evaluating GEM detectors for the upgrade of the muon system. This contribution will focus on the R&D performed on chambers design features and will discuss the performance of the upgraded detector