Oligophosphine-thiocyanate Copper(I) and Silver(I) Complexes and Their Borane Derivatives Showing Delayed Fluorescence

Abstract

The series of chelating phosphine ligands, which contain bidentate P 2 (bis[(2-diphenylphosphino)phenyl] ether, DPEphos; 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, Xantphos; 1,2-bis(diphenylphosphino)benzene, dppb), tridentate P 3 (bis(2-diphenylphosphinophenyl)phenylphosphine), and tetradentate P 4 (tris(2-diphenylphosphino)phenylphosphine) ligands, was used for the preparation of the corresponding dinuclear [M(μ 2 -SCN) P 2 ] 2 (M = Cu, 1 , 3 , 5 ; M = Ag, 2 , 4 , 6 ) and mononuclear [CuNCS( P 3 /P 4 )] ( 7 , 9 ) and [AgSCN( P 3 /P 4 )] ( 8 , 10 ) complexes. The reactions of P 4 with silver salts in a 1:2 molar ratio produce tetranuclear clusters [Ag 2 (μ 3 -SCN)(t-SCN)( P 4 )] 2 ( 11 ) and [Ag 2 (μ 3 -SCN)( P 4 )] 2 2+ ( 12 ). Complexes 7 – 11 bearing terminally coordinated SCN ligands were efficiently converted into derivatives 13 – 17 with the weakly coordinating – SCN:B(C 6 F 5 ) 3 isothiocyanatoborate ligand. Compounds 1 and 5 – 17 exhibit thermally activated delayed fluorescence (TADF) behavior in the solid state. The excited states of thiocyanate species are dominated by the ligand to ligand SCN → π(phosphine) charge transfer transitions mixed with a variable contribution of MLCT. The boronation of SCN groups changes the nature of both the S 1 and T 1 states to (L + M)LCT d,p(M, P) → π(phosphine). The localization of the excited states on the aromatic systems of the phosphine ligands determines a wide range of luminescence energies achieved for the title complexes (λ em varies from 448 nm for 1 to 630 nm for 10c ). The emission of compounds 10 and 15 , based on the P 4 ligand, strongly depends on the solid-state packing (λ em = 505 and 625 nm for...

Recent Advances in Solid‐State Lighting Devices Using Transition Metal Complexes Exhibiting Thermally Activated Delayed Fluorescent Emission Mechanism

“…Additionally, their τ and Δ E ST are often smaller. [ 105,107,132,152–157 ] In contrast to the above mentioned, silver(I) complexes have scarcely been applied to lighting devices. [ 158–161 ]…”

Photostable Ruthenium(II) Isocyanoborato Luminophores and Their Use in Energy Transfer and Photoredox Catalysis

“…Important prior work on isocyanoborato complexes focused on 5d metals including Ir(III), 55 Re(I), 56 − 59 and Os(II) 61 as well as on Ni(II), 62 Pd(II), 63 Pt(II), 64 Cu(I), 60 , 65 and Ag(I). 60 Very recently, Ru(II) and Fe(II) isocyanoborato complexes were studied in the context of electrochemistry and spectroscopy, but their photoreactivity and photochemistry have not yet been reported.…”

“…Important prior work on isocyanoborato complexes focused on 5d metals including Ir(III), 55 Re(I), 56 − 59 and Os(II) 61 as well as on Ni(II), 62 Pd(II), 63 Pt(II), 64 Cu(I), 60 , 65 and Ag(I). 60 Very recently, Ru(II) and Fe(II) isocyanoborato complexes were studied in the context of electrochemistry and spectroscopy, but their photoreactivity and photochemistry have not yet been reported. 52 − 54 Attachment of B(C 6 F 5 ) moieties to the cyanide ligands of heteroleptic complexes with α-diimine chelates usually results in the stabilization of the metal-centered d orbitals, whereas the diimine π* orbitals are less affected.…”

Cyan-Emitting Cu(I) Complexes and Their Luminescent Metallopolymers

“…The Stokes shifts are substantial (1.33 eV for 5a and 5b , 1.24 eV for 5c and 1.30 eV for 5d ), which, together with the observation that the luminescence is quenched in air-equilibrated solutions, are firm evidence of a triplet nature of the excited state. However, as several Cu(I) complexes have been demonstrated to show thermally activated fluorescence (TADF), [ 19 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ] this cannot be excluded at this stage. The excited state lifetimes in solution are in the order of one microsecond, in addition to complex 5c which shows a lifetime of 83 ns.…”