Gill Langhoff (sharekayak3)
Furthermore, multiple-stage tandem mass spectrometry (MS3 CID) provides supplementary and valuable structural information through the generation of characteristic parent-structure-dependent fragment ions.Two new bichromophoric complexes, [Fe(bim-ant)2]2+ and [Fe(bim-pyr)2]2+ ([H2-bim]2+ = 1,1'-(pyridine-2,6-diyl)bis(3-methyl-1H-imidazol-3-ium); ant = 9-anthracenyl; pyr = 1-pyrenyl), are investigated to explore the possibility of tuning the excited-state behavior in photoactive iron(II) complexes to design substitutes for noble-metal compounds. The ground-state properties of both complexes are characterized thoroughly by electrochemical methods and optical absorption spectroscopy, complemented by time-dependent density functional theory calculations. The excited states are investigated by static and time-resolved luminescence and femtosecond transient absorption spectroscopy. Both complexes exhibit room temperature luminescence, which originates from singlet states dominated by the chromophore (1Chrom). In the cationic pro-ligands and in the iron(II) complexes, the emission is shifted to red by up to 110 nm (5780 cm-1). This offers the possibility of tuning the organic chromophore emission by metal-ion coordination. The fluorescence lifetimes of the complexes are in the nanosecond range, while triplet metal-to-ligand charge-transfer (3MLCT) lifetimes are around 14 ps. An antenna effect as in ruthenium(II) polypyridine complexes connected to an organic chromophore is found in the form of an internal conversion within 3.4 ns from the 1Chrom to the 1MLCT states. check details Because no singlet oxygen forms from triplet oxygen in the presence of the iron(II) complexes and light, efficient intersystem crossing to the triplet state of the organic chromophore (3Chrom) is not promoted in the iron(II) complexes.It has been shown extensively that glycosaminoglycan (GAG)-protein interactions can induce, accelerate, and impede the clearance of amyloid fibrils associated with systemic and localized amyloidosis. Obtaining molecular details of these interactions is fundamental to our understanding of amyloid disease. Consequently, there is a need for analytical approaches that can identify protein conformational transitions and simultaneously characterize heparin interactions. By combining Raman spectroscopy with two-dimensional (2D) perturbation correlation moving window (2DPCMW) analysis, we have successfully identified changes in protein secondary structure during pH- and heparin-induced fibril formation of apolipoprotein A-I (apoA-I) associated with atherosclerosis. Furthermore, from the 2DPCMW, we have identified peak shifts and intensity variations in Raman peaks arising from different heparan sulfate moieties, indicating that protein-heparin interactions vary at different heparin concentrations. Raman spectroscopy thus reveals new mechanistic insights into the role of GAGs during amyloid fibril formation.The electrochemical reduction of CO2 using intermittent renewable electricity is an attractive strategy for producing value-added fuels and chemicals, but until now, it has been greatly hindered by the shortage of high-performance electrocatalysts. In this study, we have demonstrated a type of molecular-catalyst-based hybrid material by the polymerization of cobalt phthalocyanine (CoPc) on a three-dimensional (3D) g-C3N4 nanosheet-carbon nanotube support for the aqueous electrochemical reduction of CO2. The electrocatalytic results show that the obtained composite can selectively transform CO2 to CO with considerable Faradaic efficiency (FE) of 95 ± 1.8%, a turnover frequency of 4.9 ± 0.2 s-1, and excellent long-term stability over 24 h at -0.8 V vs the reversible hydrogen electrode (RHE). In comparison to the analogous hybrid electrocatalysts prepared by the drop-drying or dip-coating method, the polymeric form of the molecular catalyst immobilized on 3D carbonaceous materials with an interconnected network enlarges the electroch
