Highly Robust Rhenium(I) Bipyridyl Complexes Containing Dipyrromethene-BF2 Chromophores for Visible Light-Driven CO2 Reduction

Graphical CO 2 photoreduction : Toward building robust artificial photosynthetic systems, a series of single-active-site rhenium bipyridyl complexes with dipyrromethene-BF 2 units exhibit outstanding catalytic efficiency for visible light-driven-CO 2 reduction. New rhenium bipyridyl complexes with dipyrromethene-BF 2 chromophores (A-ReBDP-CZ, A-ReBDP 2 , ReBDP-CZ, and ReBDP 2 ) were developed for highly efficient photocatalytic carbon dioxide (CO 2 ) reduction to carbon monoxide (CO). These catalysts consisted of two moderate electron-deficient groups (dipyrromethene-BF 2 , BDP) as the visible-light-harvesting antenna as well as both electron donor ( N -phenylcarbazole, CZ) and acceptor (BDP) on Re bipyridyl framework. Among ReBDP-CZ and ReBDP 2 complexes, the ReBDP 2 incorporating two electron-deficient BDP chromophores had a longer-lived photoexcited state (182.4 μs) and a twofold enhanced molar absorption coefficient ( ϵ =157000 m −1 cm −1 ) compared with ReBDP-CZ. Thus, ReBDP 2 achieved the superior photocatalytic reactivity and stability with a CO turnover number (TON CO ) value as high as 1323 and quantum yield ( Φ CO ) up to 55 %, which was the most excellent photocatalysis efficiency among the single-active-site Re catalysts without additional photosensitizer. Furthermore, the acetylene-bridged linker was detrimental to the photoactivity and durability of the catalyst. In brief, two BDP-based Re bipyridyl systems with outstanding catalytic performance and significant visible-light-harvesting capabilities in the solar spectrum offer a promising strategy for solar-to-fuel conversion schemes.