Reduction of CO2using a Rhenium Bipyridine Complex Containing Ancillary BODIPY Moieties.
The reduction of carbon dioxide to chemical fuels such as carbon monoxide is an important challenge in the field of renewable energy conversion. Given the thermodynamic stability of carbon dioxide, it is difficult to efficiently activate this substrate in a selective fashion and the development of new electrocatalysts for CO2reduction is of prime importance. To this end, we have prepared and studied a newfac-ReI(CO)3complex supported by a bipyridine ligand containing ancillary BODIPY moieties ([Re(BB2)(CO)3Cl]). Voltammetry experiments revealed that this system displays a rich redox chemistry under N2, as[Re(BB2)(CO)3Cl]can be reduced by up to four electrons at modest potentials. These redox events have been characterized as the ReI/0couple, and three ligand based reductions - two of which are localized on the BODIPY units. The ability of theBB2ligand to serve as a non-innocent redox reservoir is manifest in an enhanced electrocatalysis with CO2as compared to an unsubstituted Re-bipyridine complex lacking BODIPY units ([Re(bpy)(CO)3Cl]). The second order rate constant for reduction of CO2by[Re(BB2)(CO)3Cl]was measured to bek= 3400 M-1s-1at an applied potential of -2.0 V versus SCE, which is roughly three times greater than the corresponding unsubstituted Re-bipyridine homologue. Photophysical and photochemical studies were also carried out to determine if[Re(BB2)(CO)3Cl]was a competent platform for CO2reduction using visible light. These experiments showed that this complex supports unusual excited state dynamics that precludes efficient CO2reduction and are distinct from those that are typically observed forfac-ReI(CO)3complexes.
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716.
Justin J
JJ
Teesdale
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716.
Allen J
AJ
Pistner
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716.
Glenn P A
GP
Yap
Chemical Sciences Division Oak Ridge National Laboratory, Oak Ridge, TN, 37831.
Ying-Zhong
YZ
Ma
Chemical Sciences Division Oak Ridge National Laboratory, Oak Ridge, TN, 37831.
Daniel A
DA
Lutterman
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716.
Joel
J
Rosenthal
BODIPY; carbon dioxide; catalysis; electrochemistry; photochemistry; rhenium bipyridine derivatives