Molybdopterin is an essential cofactor for all forms of life. The cofactor is composed of a pterin moiety appended to a dithiolene‐functionalized pyran ring, and through the dithiolene moiety it binds metal ions. Different synthetic strategies for dithiolene‐functionalized pyran precursors that have been designed and synthesized are discussed. These precursors also harbor 1,2‐diketone or osone functionality that has been condensed with 1,2‐diaminobenzene or other heterocycles resulting in several quinoxaline or pterin derivatives. Use of additives improves the regioselectivity of the complexes. The molecules have been characterized by 1H and 13C NMR and IR spectroscopies, as well as by mass spectrometry. In addition, several compounds have been crystallographically characterized. The geometries of the synthesized molecules are more planar than the geometry of the cofactor found in proteins. 相似文献
Access to novel imine‐substituted 1,2‐azaborinines, as well as highly arylated boracyclohexa‐3,5‐dienes has been developed by ring expansion of boroles with diazoalkanes with varying degrees of steric bulk. The formation of a diazoalkane intermediate is also discussed for the reaction of ortho‐brominated p‐tolyl‐azide with 1,2,3,4,5‐pentaphenylborole. Structural details as well as UV/Vis spectroscopic and cyclic voltammetric data are provided. These boron‐containing heterocycles have the potential to serve as building blocks for boron‐containing materials. 相似文献
The nano SnO2-modified LiNi1/3Co1/3Mn1/3O2 was successfully prepared by a carrier transfer method. The pristine and modified samples were characterized with various techniques such as XRD, SEM, XPS and EDS. The results showed that the SnO2 particles did not enter the crystal structure of LiNi1/3Co1/ 3Mn1/3O2, many nano SnO2 particles were uniformly covered on the surface of LiNi1/3Co1/3Mn1/3O2 and the modified thin layer could inhibit the dissolution of transition metal oxides. The electrochemical tests indicated that the existence of nano SnO2 could improve the discharge capacity and rate capability owing to the decreased interfacial polarization. The cycling stability was remarkably improved at room temperature and 55 ℃. The XRD patterns of the fresh NCM electrode and after 50 cycles proved that the structural change of NCM was not so effective on the capacity fade. 相似文献
A triethylene glycol modified glassy carbon electrode(TEG–GCE) was fabricated by a controlledpotential electrolysis procedure. The performance of the film on the modified electrode surface was investigated by cyclic voltammetry with different probes. It was firstly found that while neutral pieces could penetrate the TEG film on the GCE surface, the ionic pieces, whatever it is anion or cation, was blocked by the film. This property was successfully used for determining dopamine(DA) in the presence of ascorbic acid(AA) with differential pulse voltammetry(DPV). 相似文献
The coordination polymerization of silyl‐protected ω‐alkenols such as ω‐alken‐α‐oxytriisopropylsilanes 1 provides poly(ω‐alkenyl‐α‐oxytriisopropylsilalne)s with a highly isospecific microstructure ([mmmm] > 95%) when a combination of [OSSO]‐type bis(phenolato) dichloro zirconium(IV) complex 2 and dried methylaluminoxane is used as the precatalyst and activator, respectively. The resulting siloxy‐substituted polymers could be efficiently transformed into the corresponding functionalized polyolefins, which contained up to 90% acetyl groups and ≈7% hydroxy groups in the terminal side chains.