Blue-Emissive Cobalt(III) Complexes and Their Use in the Photocatalytic Trifluoromethylation of Polycyclic Aromatic Hydrocarbons

Amlan K Pal; Chenfei Li; Garry S Hanan; Eli Zysman-Colman

doi:10.1002/anie.201802532

Blue-Emissive Cobalt(III) Complexes and Their Use in the Photocatalytic Trifluoromethylation of Polycyclic Aromatic Hydrocarbons

Angew Chem Int Ed Engl. 2018 Jul 2;57(27):8027-8031. doi: 10.1002/anie.201802532. Epub 2018 Jun 4.

Authors

Amlan K Pal^{1

2}, Chenfei Li², Garry S Hanan¹, Eli Zysman-Colman²

Affiliations

¹ Département de Chimie, Université de Montréal, Montréal, Québec, H3T 1J4, Canada.
² Organic Semiconductor Center, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK.

PMID: 29726073
DOI: 10.1002/anie.201802532

Abstract

Room-temperature luminescent Co^III complexes (1 and 2) are presented that exhibit intense ligand-to-metal and ligand-to-ligand charge transfer absorption in the low-energy UV region (λ_abs ≈360-400 nm) and low-negative quasi-reversible reduction events (E^1/2_(red) =-0.58 V and -0.39 V vs. SCE for 1 and 2, respectively). The blue emission of 1 and 2 at RT is due to the large bite angles and strong σ-donation of the ligands, the combined effect of which helps to separate the emissive ³ LMCT (triplet ligand-to-metal charge transfer) and the non-emissive ³ MC (triplet metal-centered) states. 1 and 2 were found to be powerful photo-oxidants (ECoIII*/CoII =2.26 V and 2.75 V vs. SCE of 1 and 2, respectively) and were used as inexpensive photoredox catalysts for the regioselective mono(trifluoromethylation) of polycyclic aromatic hydrocarbons (PAHs) in good yields (ca. 40-58 %).

Keywords: DFT calculations; electrochemistry; emissive CoIII complexes; photophysics; photoredox catalysis.

Publication types

Research Support, Non-U.S. Gov't