Search results for "Metals"
showing 10 items of 2013 documents
Luminescence and vacuum ultraviolet excitation spectroscopy of samarium doped SrB4O7
2020
Abstract Sm2+ and Sm3+ co-doped SrB4O7 could be utilized in several high-level optical devices and fundamental knowledge about the optical behavior of these materials benefits the development of luminescent applications. Herein, we report luminescence and its vacuum ultraviolet (VUV) excitation spectra in samarium doped SrB4O7. Both, Sm2+ and Sm3+ luminescence centers have been examined and distinguished in the emission and the excitation spectra investigated under synchrotron radiation. The contribution of either Sm2+ or Sm3+ emission lines into the emission spectra heavily depended on the excitation energy, and strong f-f transitions of both Sm2+ and Sm3+ were detected. At 10 K, a broad i…
Differential study of substituted and unsubstituted cobalt phthalocyanines for gas sensor applications
2011
Abstract The conductivity of CoPc (cobalt phthalocyanine) and Co[(SO3Na)2,3Pc] was measured under a flow of two different gases (NH3 and O3), during exposure/recovery cycles. It appears that the relative responses are linearly related to the concentration, in the 20–200 ppb range for O3 and in the 20–200 ppm range for NH3. Observed during time, the sensing parameters allow a qualitative understanding of the kinetics. The comparative study of those products under both different gases gave interesting results for sensor applications. Whereas CoPc is sensitive to both gases, its sulfonated counterpart is only sensitive to NH3.
Room temperature hysteretic spin crossover in a new cyanoheterometallic framework.
2019
A new iron(II)-based spin-crossover compound with thermal hysteresis operating under ambient conditions is reported. This complex exhibits a high reproducibility of the spin transition in many successive thermal cycles, stability of both spin states at room temperature and an attractive operational temperature range.
Inhibitoren der Korrosion (14). pH-Wert-Änderungen in Suspensionen von Eisen in 0, 2 m NaCl-Lösungen unter den Bedingungen der Sauerstoffkorrosion
1971
In einer geeigneten Apparatur werden in Suspensionen von Eisen bei unterschiedlichen Reaktionsbedingungen die pH-Werte laufend bestimmt. Es wurden folgende Ergebnisse erhalten: 1 In einer Suspension van 25 g Carbonyleisenpulver in 100 m reinem Wasser andert sich weder unter N2 nach unter O2 der PH-Wert. 2 Schuttelt man 25 g Carbonyleisenpulver unter 100ml 0,2 m NaCl-Losung, so steigt innerhalb von drei bis acht Minuten der PH-Wert van 6,60 auf 9,4-9,6 an. 3 Durch Bestimmung der Menge an gelostem Fe(OH)2 und Umrechnung in pH-Einheiten kann gezeigt werden, das der pH-Wert-Anstieg zuruckgeht. Corrosion inhibitors (14) pH variations in suspensions of iron in 0.2 m NaCl solutions under condition…
Unexpected metal-free synthesis of trifluoromethyl arenes via tandem coupling of dicyanoalkenes and conjugated fluorinated sulfinyl imines
2021
A novel strategy for the synthesis of policyclic trifluoromethyl arenes has been devised. It involves a DBU-promoted tandem cycloaromatization reaction of dicyanoalkenes and fluorinated conjugated sulfinyl imines. This unprecedented transformation is a metal-free and air-tolerant process that takes place from readily available starting materials under mild reaction conditions.
Unveiling the reaction mechanism of novel copper N-alkylated tetra-azacyclophanes with outstanding superoxide dismutase activity.
2020
Quantum chemical and multiscale calculations reveal the mechanistic pathway of two superoxide dismutase mimetic N-alkylated tetra-azacyclophane copper complexes with remarkable activity. The arrangement of the binding site afforded by the bulky alkyl substituents and the coordinated water molecule as a proton source play key roles in the reaction mechanism.
Über eine neue Methode zum Nachweis des als Primärprodukt der Autoxydation der Metalle Eisen, Nickel und Kobalt in Säure- und Salzlösungen gebildeten…
1971
H2O2 als Zwischenprodukt der Autoxydation (bzw. · OOH oder · OH) kann mit Hilfe der Phosphin-, Phosphinoxid- Methode bei Fe, Ni und Co wirksamer als mit Hilfe der Jodometrie erfast werden. In saurem Medium sind Tris-(m-aminophenyl)-phosphin (1), im alkalischen Bereich Tris-(p-carboxyphenyl)- phosphin (2) wirksame auch fur quantitative Bestimmungen geeignete Reagentien auf H2O2 · 1 und 2 reagieren bei hoheren Konzentrationen bis zu 20 ma1 schneller mit H2O2 als dieses mit der Eisengrenzflache. Ni und Co erzeugen mehr H2O2 als Fe. Bei Eisen entsteht im neutralen Medium mehr H2O2 als im sauren Bereich. Die unterschiedlichen Anfangsgeschwindigkeiten des Sauerstoffverbrauchs in sauerstoffhaltige…
New sulfonamide complexes with essential metal ions [Cu (II), Co (II), Ni (II) and Zn (II)]. Effect of the geometry and the metal ion on DNA binding …
2019
Abstract Mixed divalent Cu, Co, Ni and Zn complexes containing the new sulfonamide ligand N–(2–(pyridin–2–yl)ethyl)quinoline–8–sulfonamide (HQSEP) were prepared and characterized by physico-chemical techniques. The tetracoordinate [Cu(QSEP)X] [X = Br (1), Cl (2)] compounds present a seesaw geometry (τ4 = 0.56 (1) and 0.50 (2)). The Cu(II) in the [Cu(QSEP)(NO3)(MeOH)] (3) complex is five coordinate with a slightly distorted SP geometry (τ = 0.11). The [M(QSEP)(benz)] [M = Cu(II) (4), Ni(II) (5), Co(II) (6) and Zn(II) (7); benz = benzoate] compounds are configurationally isotypic. The coordination geometries of the M(II) ions can be best described as distorted SP (τ = 0.29, 0.15, 0.34 and 0.1…
Computational simulations on the binding and reactivity of a nitrile inhibitor of the SARS-CoV-2 main protease.
2021
We present a detailed computational analysis of the binding mode and reactivity of the novel oral inhibitor PF-07321332 developed against the SARS-CoV-2 3CL protease. Alchemical free energy calculations suggest that positions P3 and P4 could be susceptible to improvement in order to get a larger binding strength. QM/MM simulations unveil the reaction mechanism for covalent inhibition, showing that the nitrile warhead facilitates the recruitment of a water molecule for the proton transfer step.
An efficient probe for sensing different concentration ranges of glutathione based on AIE-active Schiff base nanoaggregates with distinct reaction me…
2018
Abstract A novel tetraphenylethene-diketopyrrolopyrrole Schiff base (TPE-DPP) was synthesized by one-pot protocol. Based on thiol group and acid-base property of glutathione, nanoaggregates of TPE-DPP for sensitive and selective detection of diff ;erent concentration ranges of glutathione by two distinct reaction mechanisms was reported. It showed a turn-on mode of fluorescence signals towards low concentration of GSH by hydrolysis of TPE-DPP, but a ratiometric mode of fluorescence signal was elicited towards high concentration of GSH by addition reaction of thiol with TPE-DPP. What’s more, the probe was successfully utilized for monitoring GSH in living cells.