Bis(tridentate) Ruthenium–Terpyridine Complexes Featuring Microsecond Excited-State Lifetimes

Abstract

A series of heteroleptic bis(tridentate) ruthenium(II) complexes, each bearing a substituted 2,2':6',2″-terpyridine (terpy) ligand, is characterized by room temperature microsecond excited-state lifetimes. This observation is a consequence of the strongly σ-donating and weakly π-accepting tridentate carbene ligand, 2',6'-bis(1-mesityl-3-methyl-1,2,3-triazol-4-yl-5-idene)pyridine (C^N^C), adjacent to the terpy maintaining a large separation between the ligand field and metal-to-ligand charge transfer (MLCT) states while also preserving a large (3)MLCT energy. The observed lifetimes are the highest documented lifetimes for unimolecular ruthenium(II) complexes and are four orders in magnitude higher than that associated with [Ru(terpy)(2)](2+).

Predicting Structures of Ru-Centered Dyes: A Computational Screening Tool

“…In addition, Ru–C bound complexes were chosen including cyclometalated derivatives of TPy and DQP, Ru(NCN) 2 (NCN = dipyridylbenzene) 48 and Ru(DQB) 2 (DQB = 1,3-diquinolin-8-ylbenzene), 49 respectively. Finally, carbene homoleptic Ru(DQIm) 2 (DQIm = 1,3- bis (8-quinolinyl)-imidazole), and heteroleptic Ru(CPyC)(TPy) (CPyC = 2′,6′- bis (1-mesityl-3-methyl-1,2,3-triazol-4-yl-5-idene)pyridine) 20 complexes are also represented.…”

A study of acridine and acridinium-substituted bis(terpyridine)zinc(ii) and ruthenium(ii) complexes as photosensitizers for O2 (1Δg) generation

“…Especially for terpyridine complexes, which lack on prolonged excited state lifetimes compared to [Ru(bpy) 3 ] 2+ , rational design has lead to lifetimes in the μs-regime. This was achieved by manipulation of the terpyridine ligand itself, 40,41 but also by attachment of multiple chromophores with a matching triplet level. 42 The choice of a suitable chromophore for such purposes is a priori difficult and certain limitations apply as summarized by Zhao et al, 18 i.e., one or several chromophores tethered to the metal-coordination side with an excited singlet state higher in energy than the singlet state of interest may serve as an additional photon absorber ("antenna effect").…”

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

“…[3] Many strategies have been used to improve the photophysical properties of these complexes with the most popular focusing on the manipulation of the energies of non-emissive 3 MC states relative to emissive triplet metal-to-ligand charge transfer ( 3 MLCT) states. 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. 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.…”