Search

Nachhaltige Kohlenstoffpunkte, die an der Oberfläche Oximestergruppen enthalten, welche einer homolytischen Bindungsspaltung folgen, zeigen ein Potential als Photoinitiatoren für die traditionelle freie radikalische Photopolymerisation. Die Kohlenstoffpunkte wurden nach einem solvothermalen Verfahren aus nachhaltigem Furfural, welches über Lignocellulose erhältlich ist, hergestellt. Aldehydgruppen der Oberfläche reagierten mit Hydroxylamin zu dem entsprechendem Oxim, während die Reaktion mit Benzoylchlorid zu einem bio‐basierten Typ I Photoinitiator (CD‐PI) führte, welcher nachhaltige Kohlenstoffpunkte enthält. Die Fähigkeit zur Photoinitiierung wurde unter UV‐Bestrahlung bei 365 nm mit dem traditionellen Photoinitiator (PI) Ethyl (2,4,6‐trimethyl benzoyl) phenyl phosphinat (TPO‐L) mittels Echtteit FTIR Spektroskopie verglichen. Die auf einem Gemisch von Urethandimethacrylat (UDMA) und Tripropylenglykoldiacrylat (TPGDA) basierte Photopolymerzusammensetzung führte unter Verwendung von CD‐PI oder TPO‐L zu einem ähnlichen Endumsatz von etwa 70 %. Dennoch erschien das vernetzte Material im Fall der Zusammensetzungen, die mit CD‐PI verarbeitet wurden, homogen, während jene, die mit TPO‐L hergestellt wurden, heterogen waren, was durch die beiden Glasübergangstemperaturen gezeigt wurde. Außerdem war die Migrationsgeschwindigkeit von CD‐PI in den gehärteten Proben geringer im Vergleich zu jenen Proben für die TPO‐L als PI eingesetzt wurde. [ABSTRACT FROM AUTHOR]

A novel Michelson interferometric hydrogen sulphide sensor coated with copper/reduced graphene oxide (Cu/rGO) composite membrane is proposed and fabricated. A section of endlessly photonic crystal fibre (EPCF) was sandwiched in two single-mode fibres (SMFs). One SMF was spliced and tapered with EPCF; the other SMF was connected with the Faraday rotator mirror to construct the Michelson structure. The cladding of the EPCF was coated by the Cu/rGO-sensing membrane, which was prepared by the dip-coating method. The obtained Cu/rGO-sensing film has a length of 25.0 mm. The fabricated sensing membrane is characterised by the scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and so on. Experimental results demonstrated that the Cu/rGO-sensing film has a 24.56-nm thickness with a compact and uniform appearance. The XPS and Raman spectra indicate that there are three elements (C, O, and Cu), which are consistent with the expected compositions of the Cu/rGO membrane. With the increase of concentration of hydrogen sulphide, the interference spectra appear red-shifted. The linearity of 0.97662 and the sensitivity of 13.23 pm/ppm are achieved. In addition, the dynamic response and recovery time of the sensor are approximately 70 and 88 s, respectively. The surface adsorption energies of the film are calculated by the density functional theory. The theoretical results are in good agreement with the experimental findings. This sensor has some key advantages of small size, simple structure, easy fabrication, and great applicability for detecting the trace hydrogen sulphide. [ABSTRACT FROM AUTHOR]

Spirofluorenyl-1,2,4-oxadiazinan-5-ones are prepared in good to excellent yields through metal-free [3+3] cycloaddition of N -vinyl fluorenone nitrones and aza-oxyallyl cations under mild reaction conditions. Detailed studies reveal that N -vinyl fluorenone nitrones show greater reactivity in [3+3] cycloadditions with aza-oxyallyl cations compared to N -alkyl/aryl fluorenone nitrones. The spirofluorenyl-1,2,4-oxadiazinan-5-ones are easily prepared on gram scale. The present method features mild reaction conditions, broad substrate scope, good functional group tolerance and efficient [3+3] cycloadditions of 9-fluorenone nitrones. [ABSTRACT FROM AUTHOR]

C22H26O6, orthorhombic, P212121 (no. 19), a = 7.6648(5) Å, b = 11.2663(6) Å, c = 22.7321(7) Å, V = 1963.0(2) Å3, Z = 4, Rgt(F) = 0.0652, wRref(F2) = 0.1399, T = 273(2) K. [ABSTRACT FROM AUTHOR]

C26H27ClN8NiO7, triclinic, P1̄ (no. 2), a = 9.893(2) Å, b = 11.503(2) Å, c = 13.295(3) Å, α = 78.77(3)°, β = 70.52(3)°, γ = 83.40(3)°, V = 1397.0(6) Å3, Z = 2, Rgt(F) = 0.0423, wRref(F2) = 0.1032, T = 153.15 K. [ABSTRACT FROM AUTHOR]

C16H8O4, monoclinic, Pc (no. 7), a = 3.7133(1) Å, b = 9.7214(4) (2) Å, c = 15.5765(6) Å, β = 96.121(2)°, V = 559.08(3) Å3, Z = 2, Rgt(F) = 0.0506, wRref(F2) = 0.1274, T = 150(2) K. [ABSTRACT FROM AUTHOR]

Durch äußere Stimuli ausgelöste Strukturumwandlungen spielen bei vielen biologischen Vorgängen eine wichtige Rolle, oft als Teil kinetisch gesteuerter Szenarien. Licht hat sich bei supramolekularen Nachbildungen solcher Systeme als perfekter externer Trigger erwiesen. Hier berichten wir über die lichtgesteuerte Strukturumwandlung eines kleinen, selbstassemblierten Pd3L6 ‐ Ringes, aufgebaut aus photochromen Dithienylethen(DTE) ‐ Liganden, zu einer rhombenkuboktaedrischen Pd24L48 ‐ Sphäre mit einem Durchmesser von 6.4 nm. Je nach Wahl der Wellenlänge kann dieser Prozess vollständig umgekehrt werden, wie durch NMR ‐ , UV/Vis ‐ und MS ‐ Messungen gezeigt werden konnte. Zudem konnte die Bildung der Sphäre mittels AFM, TEM und GISAXS nachgewiesen werden. Aufgrund unterschiedlicher Konformationen der Photoschalter in den isomeren Konstrukten zeigen die Geschwindigkeitskonstanten der Umwandlung zwischen beiden Strukturen eine starke Abhängigkeit von der Schaltrichtung. Licht an! In Position! Bestrahlung mit unterschiedlichen Wellenlängen steuert die reversible Umwandlung zwischen einem kleinem, selbstassemblierten Pd3L6 ‐ Ring basierend auf photochromen Dithienylethen ‐ Liganden und einer rhombenkuboktaedrischen Pd24L48 ‐ Sphäre mit 7 nm Durchmesser. [ABSTRACT FROM AUTHOR]

A one-pot, three-component difunctionalization of quinones with indoles and arylamines has been developed to synthesize indole functionalized p -iminoquinones derivatives. The approach employed AgOAc as the catalyst in the presence of 3-chlorophenylboronic acid, giving a series of indole functionalized p -iminoquinones derivatives in moderate to good yields. This catalytic approach represents a step-economic and convenient strategy for the difunctionalization of quinones. A plausible reaction pathway has been proposed based on a series of control experiments. [ABSTRACT FROM AUTHOR]

In addition to taste and melting behavior, the gloss is an important quality criterion of chocolate products. Differences considering the gloss on products can be attributed to different causes in the production process. The chocolate that has been pre‐crystallized by shearing and supercooling is further cooled, crystallized and transported as a solid chocolate out of the cooling process. The cooling of the chocolate is largely unexplored in a paternoster refrigerator and therefore the resulting streaming profile and temperature profile are numerically studied in this work. [ABSTRACT FROM AUTHOR]

A facile and efficient method for the synthesis of 3-aryl-4-hydroxy-1,3-thiazolidin-2-ones by the reaction of 1,4-dithiane-2,5-diol with acyl azides is reported. This reaction proceeded well at 80 °C to afford products in excellent yields for a wide range of substrates. A possible mechanism has been proposed. [ABSTRACT FROM AUTHOR]

An iron-catalyzed allyation of isoquinoline with potassium allyltrifluoroborate is described. The operation of this reaction is very simple and highly practical. The diastereoisomer having two adjacent chiral centers were obtained in single anti -configuration. [ABSTRACT FROM AUTHOR]

The stress corrosion cracking (SCC) behaviors of Z3CN20.09M, 304L, and 316L austenitic stainless steels (SSs) after milling operation in boiling magnesium chloride solution were investigated by scanning electron microscopy (SEM), X-ray diffraction, and 3D profilometer. The experimental results indicated that the roughness and residual stress increased with increasing feed rate of all specimens. The depth of deformation layer after milling operation reached about 150 µm shown as persistent slip bands (PSBs) were formed, leading to hardness enhanced obviously. After SCC tests in boiling magnesium chloride solution, the crack densities increased with increasing feed rate of the Z3CN20.09M SS specimens. However, the crack densities decreased as well as the intergranular (IG) cracking percentages increased with increasing feed rate of the 304L and 316L SS. [ABSTRACT FROM AUTHOR]

Ein difunktioneller chiraler Sulfid ‐ Katalysator und ein stabiles elektrophiles SCF3 ‐ Reagens ermöglichen die von X. Zhao et al. in der Zuschrift auf S. 5940 ff. vorgestellte enantioselektive trifluormethylthiolierende Lactonisierung. Die Reaktion verläuft nur, wenn die Amid ‐ und Sulfid ‐ Einheiten des Katalysators kooperieren, ähnlich den beiden Scheren eines Krebses, die gemeinsam Fisch fangen. [ABSTRACT FROM AUTHOR]