Tuning the Photophysical and Excited State Properties of Phosphorescent Iridium(III) Complexes by Polycyclic Unit Substitution

摘要

Two novel N‐embedded polycyclic units functionalized phosphorescent iridium(III) complexes (>Ir‐1 and >Ir‐2) with substituents in different positions have been prepared. Complex >Ir‐1 bearing the substituent at the 3‐position shows a distinct blue shift single‐peak emission (524 nm) with a higher luminescence efficiency (ΦPL=42 %) and shorter emission lifetime (τ=282 ns) by comparison with 4‐position substitution based complex >Ir‐2 (ΦPL=23 %, τ=562 ns), which exhibits a dual‐peak emission (564 nm and 602 nm), and phosphorescence color can be tuned from green to yellow. In addition, DFT calculations demonstrate that unusual ligand‐to‐metal charge transfer (³LMCT) excited state property can be found in >Ir‐2, which is in contrast to metal‐to‐ligand charge transfer (³MLCT) excited state character in >Ir‐1. This result can be attribute to strong electron‐donating character and 4‐position substitution effect of the unit.