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Blue‐Emissive Cobalt(III) Complexes and Their Use in the Photocatalytic Trifluoromethylation of Polycyclic Aromatic Hydrocarbons
Author(s) -
Pal Amlan K.,
Li Chenfei,
Hanan Garry S.,
ZysmanColman Eli
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201802532
Subject(s) - trifluoromethylation , chemistry , ligand (biochemistry) , photochemistry , cobalt , metal , photocatalysis , regioselectivity , catalysis , inorganic chemistry , organic chemistry , alkyl , trifluoromethyl , biochemistry , receptor
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 %).