Chromium complexes for luminescence, solar cells, photoredox catalysis, upconversion, and phototriggered NO release

Abstract

Cr(iii) and Cr(0) complexes are earth-abundant alternatives to photosensitizers that are commonly made from precious metals.

Deuterated Molecular Ruby with Record Luminescence Quantum Yield

“…[9] The" molecular ruby" 1 3+ Scheme 1. [8,10,11,[14][15][16] In many of the above-mentioned complexes (Scheme 1), detrimental ligand-field excited states, [17,18] which lead to nonradiative deactivation, are either absent (d 0 and d 10 electron configuration) or have been successfully shifted to highenough energy,sothat these states do not provide an efficient deactivation pathway.A st hese typically dissociative ligandfield states are not populated for as ufficiently long time, photosubstitution is virtually impossible.This photostability is especially pronounced for 1 3+ with ah igh-energy 4 T 2 ligandfield state preventing substitution reactions (k chem ;F igure 1, center) as back-intersystem crossing (BISC) from the doublet states to the 4 T 2 state is thermodynamically impeded (k BISC ; Figure 1, center). [4][5][6][7][8] [*] C. Wang displays asharp,unprecedentedly intense spin-flip emission in the NIR with aphotoluminescence quantum yield of F = 0.11 and al uminescence lifetime of t = 898 msi nH 2 Oa tr oom temperature.…”

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

“…[4] Some fruitful approaches to destabilize the energy of the 3 MC states consist of a) introduction of strong donor ligands and b) the use of tridentate ligands that form 6-membered chelate rings to reduce the steric strain and achieve am ore octahedral geometry compared to those bearing five-membered chelate rings. Recently,W enger and Gray et al observed 3 MLCT emission of earth abundant low-valent Cr 0 , [13] Mo 0 , [14] and W 0 [15] complexes with arylisocyanide ligands. Recently,W enger and Gray et al observed 3 MLCT emission of earth abundant low-valent Cr 0 , [13] Mo 0 , [14] and W 0 [15] complexes with arylisocyanide ligands.…”

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

“…Following these approaches,Ru II , [5,6] Cr III , [7] and Fe((III), low spin) [8] complexes with strongly s-donating tridentate ligands have been shown to have dramatically longer emission lifetimes.A nother popular strategy to induce emission in 1 st row transition metals is to use d [10] metal-ions to avoid nonemissive d-d transition, for example,Cu I , [9] Ni 0 , [10] and Zn II ; [11] however, their MLCT excited states often undergo strong geometrical distortion [12] and non-radiative relaxation to the ground state can be rapid. Recently,W enger and Gray et al observed 3 MLCT emission of earth abundant low-valent Cr 0 , [13] Mo 0 , [14] and W 0 [15] complexes with arylisocyanide ligands. [16] Some of these complexes have been explored as photoredox catalysts in Diels-Alder reactions, [7] alkylations, and oxidative cyclizations, [17] trifluoromethylation of alkenes, [9] and polymerization.…”