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Multimetallic and Mixed Environment Iridium(III) Complexes: A Modular Approach to Luminescence Tuning Using a Host
Victoria E Pritchard1, Diego Rota Martir2, Eli Zysman-Colman2
1School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|March 28, 2017
Summary
New iridium(III) complexes with cyclotriguaiacylene ligands exhibit distinct photophysical properties. The L1 ligand enhances blue-shifted emission, longer lifetimes, and higher quantum yields in these iridium complexes.
Area of Science:
- Coordination Chemistry
- Photophysics
- Materials Science
Background:
- Cyclometallated iridium(III) complexes are crucial in developing advanced luminescent materials.
- Host ligands play a significant role in tuning the photophysical properties of metal complexes.
- Understanding structure-property relationships in multinuclear iridium complexes is essential for designing new functional materials.
Purpose of the Study:
- To synthesize and characterize novel mononuclear and trinuclear bis-cyclometallated iridium(III) complexes.
- To investigate the influence of different host ligands (L1 and L2) on the photophysical properties of these iridium complexes.
- To explore the behavior of iridium(III) chromophores in mixed Ir-environment complexes.
Main Methods:
- Synthesis of host ligands tris(4-[4'-methyl-2,2'-bipyridyl]methyl)cyclotriguaiacylene (L1) and tris(4-(4'-methyl-2,2'- bipyridyl)carboxy)cyclotriguaiacylene (L2).
- Preparation of mononuclear and trinuclear bis-cyclometallated iridium(III) complexes.
- Characterization using steady-state and time-resolved spectroscopy, and electrochemical investigations.
Main Results:
- Complexes with the L1 ligand exhibited blue-shifted emission in solution, longer excited-state lifetimes, and higher photoluminescence quantum yields compared to those with L2.
- Mixed bis-cyclometallated iridium(III) complexes were successfully synthesized, incorporating both phenylpyridinato (ppy) and 2,4-difluorophenylpyrinato (dFppy) ligands.
- Spectroscopic and electrochemical data indicated that the iridium(III) chromophores in mixed-environment complexes function as isolated centers, with no observed energy transfer or electronic communication.
Conclusions:
- The choice of host ligand significantly impacts the photophysical characteristics of cyclometallated iridium(III) complexes.
- The L1 ligand promotes enhanced luminescence properties in iridium(III) complexes.
- In mixed iridium-environment complexes, individual iridium centers maintain their electronic integrity, suggesting potential for independent tuning of properties within a single molecule.
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