Nickel(II) Analogues of Phosphorescent Platinum(II) Complexes with Picosecond Excited-State Decay.
Angew Chem Int Ed Engl
; 62(46): e202312851, 2023 Nov 13.
Article
en En
| MEDLINE
| ID: mdl-37732725
ABSTRACT
Square-planar NiII complexes are interesting as cheaper and more sustainable alternatives to PtII luminophores widely used in lighting and photocatalysis. We investigated the excited-state behavior of two NiII complexes, which are isostructural with two luminescent PtII complexes. The initially excited singlet metal-to-ligand charge transfer (1 MLCT) excited states in the NiII complexes decay to metal-centered (3 MC) excited states within less than 1 picosecond, followed by non-radiative relaxation of the 3 MC states to the electronic ground state within 9-21â
ps. This contrasts with the population of an emissive triplet ligand-centered (3 LC) excited state upon excitation of the PtII analogues. Structural distortions of the NiII complexes are responsible for this discrepant behavior and lead to dark 3 MC states far lower in energy than the luminescent 3 LC states of PtII compounds. Our findings suggest that if these structural distortions could be restricted by more rigid coordination environments and stronger ligand fields, the excited-state relaxation in four-coordinate NiII complexes could be decelerated such that luminescent 3 LC or 3 MLCT excited states become accessible. These insights are relevant to make NiII fit for photophysical and photochemical applications that relied on PtII until now.
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Colección:
01-internacional
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MEDLINE
Idioma:
En
Revista:
Angew Chem Int Ed Engl
Año:
2023
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Article
País de afiliación:
Suiza