The series of osmium(ii) complexes [Os(bpy)3-n(btz)n][PF6]2 (bpy = 2,2'-bipyridyl, btz = 1,1'-dibenzyl-4,4'-bi-1,2,3-triazolyl, n = 0, n = 1, n = 2, n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For , a dramatic blue-shift relative to the absorption profile for is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(ii) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes and display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, (3)MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of to are destabilised by between 0.60 and 0.79 eV relative to their Ru(ii) analogues. The homoleptic complex appears to display extremely weak room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes to display room temperature luminescent emission and readily reversible Os(ii)/(iii) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on and show inferior current density and luminance than LECs based on , the device utilising shows the highest external quantum efficiency at 0.3%.

The effects on photo-and electroluminescent properties of structurally modifying the bisphosphane in [Cu(N^N)(P^P)]+ complexes (N^N = bpy, 6-Mebpy, 6,6′-Me2bpy) are described.

New cycloplatinated N-heterocyclic carbene (NHC) compounds with chelate diphosphines (P^P) as ancillary ligands: [Pt(R-C^C*)(P^P)]PF6 (R = H, P^P = dppm 1A, dppe 2A, dppbz 3A; R = CN, P^P = dppm 1B, dppe 2B, dppbz 3B) have been prepared from the corresponding starting material [{Pt(R-C^C*)(µ-Cl)}2] (R = H, A, R = CN, B) and fullycharacterized. The new compound A has been prepared by a stepwise protocol. The photophysical properties of 1A-3A and 1B-3B have been widely studied and supported by the time-dependent-density functional theory (TD-DFT). These compounds show an efficient blue (dppe, dppbz) or cyan (dppm) emission in PMMA films (5%wt), with photoluminescence quantum yield (PLQY) ranging from 30% to 87% under argon atmosphere. This emission has been assigned mainly to transitions from 3 ILCT [π(NHC) → 2 π*(NHC)] excited states with some 3 LL'CT [π(NHC) → π*(P^P)] character. The electroluminescence of these materials in proof-of-concept solution processed OLEDs containing 3A and 3B as dopants was investigated. The CIE coordinates for devices based on 3A (0.22, 0.41) and 3B (0.24, 0.44) fit within the sky blue region. raise the energy of the MC states hindering their photo-or thermal population and then increasing the emission quantum yield and avoiding degradation via bond-breaking processes. 20, 23 The use of didentate cyclometalated carbenes (C^C*) allows to tune the emission properties by changing the nature of both, the C^C* and the ancillary ligands. In this field high efficient blue-emitters have been reported by our group. [19][20][21][22] Those containing chelate diphosphines, such as [Pt (R-C^C*)(P^P)] PF6 (R-C= Naph, R =CO2Et, P^P: dppm (diphenylphosphinomethane), dppe (diphenylphosphinoethane), dppbz (1,2diphenylphosphino-benzene) showed high photoluminescence quantum yields (PLQY) and stability and were proved as the active components in photo-and electroluminescent devices. 21 OLEDs can be manufactured with either vacuum deposition or solution-processing techniques. The former method is suitable for small molecules that, generally, have better performance and longer stability due to the purity of the sublimated samples. [24][25][26] Vacuum deposition, however, requires accurate control on doping concentration and wastes lot of material thereby increasing the manufacturing costs. 27 Recent developments on solutionprocessable OLEDs based on small molecules have focused on optimizing efficiency while using simple processing techniques. 27 However, there are still limited examples, in particular for solution-processable OLEDs based on Pt(II) complexes. 25,26,[28][29][30][31][32][33][34][35][36][37][38][39][40] Within this perspective we decided to extend the family of [Pt(R-C^C*)(P^P)]PF6 compounds by changing the C^C* group. As result, herein we report the synthesis and the structural properties of compounds [Pt (R-C^C*)(P^P)]PF6 (R= H, P^P: dppm 1A, dppe 2A, dppbz 3A; R = CN, P^P: dppm 1B, dppe 2B, dppbz 3B). The photophysical and TD-DFT studies were also carried out, showing photoluminescence...