Structural Chemistry - Muropeptides are fragments of polymeric peptidoglycan, unique constituent of bacterial cell walls, acting as immunostimulators (adjuvants). The smallest biologically active... 相似文献
Solution-state nitroso monomer-azodioxide equilibria and conformational freedom of several aromatic dinitroso derivatives, differing in the spacer group between the aromatic rings, were studied by one- and two-dimensional variable temperature 1H NMR spectroscopy and by quantum chemical calculations. The proton signals of nitroso monomer-azodioxide mixtures revealed by low-temperature NMR were assigned and validated using B3LYP-D3/6-311+G(2d,p)/SMD level of theory. In almost all cases, a preference towards the formation of only one azodioxy isomer of aromatic dinitroso compounds was found, which was assigned to Z-dimer according to computational data. Nevertheless, the computed small energy difference between the Z- and E-isomer could not account for the extreme preference for Z-dimer formation, indicating an influence of entropic or solvent effects. The formation of shorter oligomers in solution was excluded based on integrated 1H NMR signal intensities. The experimental results indicated an average dimerization Gibbs energy of about ??5 kJ/mol at 223 K and were found to be in very good correlation with dimerization energies obtained by solution-phase optimization.
In this paper we report on facile solution combustion synthesis of erbium doped β-Ga2O3 with urea as fuel. The product was characterized using powder X-ray diffraction and transmission electron microscopy (TEM). X-ray diffraction and TEM showed that the material is nanostructured. Luminescence properties of β-Ga2O3:Er are studied with excitation in near infrared (Nd:YAG laser at 1064 nm) and visible (argon laser at 514.5 nm). A strong NIR emission of Er3+ in the window of minimal optical loss in silica based optical fibers, due to the 4I13/2→4I15/2 transition at 1.55 μm has been observed. Codoping with Yb3+ significantly increases the intensity of that important emission. 相似文献
Abstract Adducts of cadmium(II) dibenzoylmethate, Cd(dbm)2X2 (X = DMSO, H2O) were synthesized and analyzed by thermogravimetric analysis (TGA), differential-scanning calorimetry (DSC), hot-stage microscopy
(HSM), single crystal X-ray diffraction, FTIR and Raman spectroscopy, and elemental analysis. Products obtained by thermal
decomposition of the two Cd(II) complexes in oxygen, were used for quantitative analysis of cadmium in the adduct molecules.
Single-crystal X-ray diffraction analysis of the DMSO adduct revealed that it has cis configuration. The DMSO adduct crystallizes in P21/a space group, a = 17.2494(6) ?, b = 8.3251(4) ?, c = 22.2746(9) ?, β = 93.836(3)°, V = 3191.53(7) ?3, Z = 4.
Graphical abstract
Structural, Spectroscopic and Thermal Characterisation of bis (dibenzoylmethanato)Cd(II) Adducts With Dimethylsulfoxide and
WaterIvan Halasz, Michaela Horvat, Tomislav Biljan, Ernest Meštrović
Two adducts of bis(dibenzoylmethanato)Cd(II), Cd(dbm)2X2 (X = DMSO, H2O) have been synthesized and characterized.
相似文献
Strong anti-Stokes bands observed in FT-Raman spectra of Y2O3, Gd2O3 and Lu2O3 are explained by NIR luminescence of Yb3+ impurities present in sesquioxides after the excitation with the 1064 nm line of an Nd:YAG laser. Samples of Y2O3:Yb, Ga2O3:Yb, CeO2:Yb, Gd2O3:Yb and Lu2O3:Yb were prepared by solution combustion synthesis procedure using urea. All materials were investigated by FT-Raman and FT-NIR spectroscopy and characterized by X-ray powder diffraction. 相似文献
Surface-enhanced Raman scattering has been applied to study weak intermolecular interactions between small organic gelling molecules involved in the silver nanoparticle-hydrogel composite formation. Assembly and disassembly of the gelator molecules in close vicinity to embedded silver nanoparticles were followed by changes in Raman intensity of the amide II and carboxyl vibrational bands, whereas the strength of the bands related to benzene modes remained constant. This implied that the gelator molecules were strongly attached to the silver particles through the benzene units, while participating in gel structure organization by intermolecular hydrogen bonding between oxalyl amide and carboxyl groups. 相似文献