New cyclometalated Ir(iii) complexes with bulky ligands with potential applications in LEC devices: experimental and theoretical studies of their photophysical properties

Abstract

The synthesis and the electrochemical, photoluminescent and electroluminescent properties is reported for two new Ir(iii) cyclometalated complexes described as [Ir(F2ppy)2L1](PF6) and [Ir(F2ppy)2L2](PF6).

Insights into the luminescent properties of anionic cyclometalated iridium(III) complexes with ligands derived from natural products

“…Consequently, the accessibility to the 3 MC states is related to the k nr in cyclometalated Ir(III) complexes, and a high splitting energy between the 3 MC and T 1 states is required to avoid the radiationless processes. To get insights into the accessibility to the non‐radiative processes, the 3 MC states of all the complexes were optimized at the unrestricted PBE0 level of theory, starting from a distorted T 1 geometry by elongation of the metal‐ligand distances as reported in related studies . The 3 MC states involves the electron promotion between the t 2g and e g metal orbitals; due to the antibonding character of the e g orbital, the elongation of the IrC^N and/or IrO^O bonds are the main structural change in the 3 MC states .…”

“…To get insights into the accessibility to the non‐radiative processes, the 3 MC states of all the complexes were optimized at the unrestricted PBE0 level of theory, starting from a distorted T 1 geometry by elongation of the metal‐ligand distances as reported in related studies . The 3 MC states involves the electron promotion between the t 2g and e g metal orbitals; due to the antibonding character of the e g orbital, the elongation of the IrC^N and/or IrO^O bonds are the main structural change in the 3 MC states . Indeed, the IrN(C^N) distances of the 3 MC states of complexes C1 ‐ C10 are increased in up to ∼0.5 Å compared to the ground states (see Table S2 in the Supporting Information).…”

“…Table also displays the adiabatic 3 MC‐T 1 energy difference [Δ E ( 3 MC‐T 1 )] as a measure of the accessibility to the radiationless processes. The high Δ E ( 3 MC‐T 1 ) values of iTMCs have been related to its high electroluminescent performance in LEC devices . For instance, cationic Ir(III) complexes with Δ E ( 3 MC‐T 1 ) values on the range of 0.26‐0.60 eV have shown excellent electroluminescent performance in LECs, reaching a luminance of the order of 70–177 cd/m 2 at low bias .…”

Electron‐donor substituents on the dppz‐based ligands to control luminescence from dark to bright emissive state in Ir(III) complexes

“…Polypyridyl Ru(II) complexes were the first iTMCs used in LECs, however, the narrow variety of emission colors and the accessibility to populate triplet metal‐centered excited states ( 3 MC), which are preferably deactivated in non‐radiative pathways, limit their use in this application . Consequently, new coordination compounds have been used, including Cu(I), Re(I), Os(II), and Ir(III) as metal centers . Among these, the cyclometalated Ir(III) complexes are the most attractive candidates, due to strong metal‐induced spin‐orbit coupling (SOC) interaction, allowing populate the spin‐forbidden triplet excited states obtaining high phosphorescent quantum yields .…”

Role of Seroalbumin in the Cytotoxicity of cis-Dichloro Pt(II) Complexes with (N^N)-Donor Ligands Bearing Functionalized Tails

“…15 Both of them are strong DNA intercalating agents with cytotoxic activity 16,17 that displays a synergistic effect in tumor cells treated with cisplatin. 18,19 In the case of the 4,4′bis(α-styrene)-2,2′-bipyridine (bpyst) 20,21 ligand (Chart 1) the conjugation of the phenyl (Ph) ring and the ethylene fragment with the bpy unit renders this ligand very attractive due to its rigidity that enforces a plane structure. 22−24 Concerning our aims, the plane architecture makes [PtCl 2 (bpyst)] (complex 4) an interesting compound to be analyzed as a potential drug targeting DNA.…”