Showing posts with label photocatalysis. Show all posts
Showing posts with label photocatalysis. Show all posts

Friday, September 15, 2017

A unified photoredox-catalysis strategy for C(sp3)– H hydroxylation and amidation using hypervalent iodine


A unified photoredox-catalysis strategy for C(sp3)H hydroxylation and amidation using hypervalent iodine 


Guo-Xing Li,a Cristian A. Morales-Rivera,b Fang Gao,a Yaxin Wang,a Gang He,a Peng Liu *b and Gong Chen *ac
 
aState Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071, China. E-mail: gongchen@nankai.edu. cn
bDepartment of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA. E-mail: pengliu@pitt.edu
cDepartment of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, PA 16802, USA. E-mail: guc11@psu.edu
Chem. Sci. 2017, ASAP 
DOI: 10.1039/c7sc02773g
http://pubs.rsc.org/en/content/articlepdf/2017/sc/c7sc02773g?page=search

Abstract:






We report a unified photoredox-catalysis strategy for both hydroxylation and amidation of tertiary and benzylic CH bonds. Use of hydroxyl perfluorobenziodoxole (PFBlOH) oxidant is critical for efficient tertiary CH functionalization, likely due to the enhanced electrophilicity of the benziodoxole radical. Benzylic methylene CH bonds can be hydroxylated or amidated using unmodified hydroxyl benziodoxole oxidant BlOH under similar conditions. An ionic mechanism involving nucleophilic trapping of a carbocation intermediate by H2O or CH3CN cosolvent is presented.

Thursday, November 12, 2015

Phase transition-induced band edge engineering of BiVO4 to split pure water under visible light

                       

Abstract

Through phase transition-induced band edge engineering by dual doping with In and Mo, a new greenish BiVO4 (Bi1-XInXV1-XMoXO4) is developed that has a larger band gap energy than the usual yellow scheelite monoclinic BiVO4 as well as a higher (more negative) conduction band than H+/H2 potential [0 VRHE (reversible hydrogen electrode) at pH 7]. Hence, it can extract H2 from pure water by visible light-driven overall water splitting without using any sacrificial reagents. The density functional theory calculation indicates that In3+/Mo6+ dual doping triggers partial phase transformation from pure monoclinic BiVO4 to a mixture of monoclinic BiVO4 and tetragonal BiVO4, which sequentially leads to unit cell volume growth, compressive lattice strain increase, conduction band edge uplift, and band gap widening.

http://www.pnas.org/content/112/45/13774.full