Authors:Natan Straathof, Dannie Osch, Arian Schouten, Xiao Wang, Jaap Schouten, Volker Hessel, and Timothy Noël
A visible light photocatalytic metal-free perfluoroalkylation method for the functionalization of heteroarenes in continuous flow was developed. Eosin Y was the most efficient photocatalyst with regard to substrate scope, reaction time and cost prize. Faster reaction times were observed in continuous flow compared to batch due to an improved irradiation of the reaction mixture on a microscale. Several pyrroles and indoles were perfluoroalkylated within 30 min residence time (six examples). The trifluoromethylation of pyrroles and indoles was achieved by using a gas–liquid flow with CF3I as a cheap CF3 source (three examples).
Authors:Supriya Kanyal, David Jensen, Andrew Dadson, Richard Vanfleet, Robert Davis, and Matthew Linford
We describe the direct, conformal, atomic layer deposition (ALD) of silica onto carbon nanotubes (CNTs) in the microfabrication of thinlayer chromatography (TLC) plates. As before, these plates were prepared with zig-zag hedge and channel microstructures, with high aspect ratio, porous hedges. After ALD, scanning electron microscopy (SEM) showed an increase in the radius of the CNTs of 8–40 nm. X-ray photoelectron spectroscopy (XPS) showed that the plates were composed almost entirely of silicon and oxygen, without contamination of metals or other elements that might compromise chromatographic performance, e.g., aluminum. Time-of-flight secondary ion mass spectrometry confirmed the extremely low level of aluminum in the plates. The final TLC layer thickness was ca. 50 μm. Separations of a test mixture of dyes from CAMAG (Muttenz, Switzerland) on an uncoated silica plate under traditional, normal phase conditions gave efficiencies of 40,000–140,000 plates m−1 with migration distances ranging from 2 to 36 mm. A separation of two fluorescent dyes, eosin Y disodium salt and sulforhodamine B, on an amino silane-coated plate gave efficiencies of ca. 170,000 and 200,000 plates m−1, with hRF values of 76 and 88, respectively. Run times on these new plates were much faster than on conventional TLC plates.
Authors:Shaoqin Peng, Ran An, Zhisheng Wu, and Yuexiang Li
Li , YX , Guo , MM , Peng , SQ , Lu , GX , Li , SB 2009 Formation of multilayer-eosinY-sensitized TiO 2 via Fe 3+ coupling for efficient visible-light photocatalytic hydrogen evolution . Int J Hydrogen Energy 34 : 5629 – 5636 10.1016/j