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Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
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Cationic iridium(III) complexes with two carbene-based cyclometalating ligands: cis versus trans isomers
Filippo Monti1, Maria Grazia I La Placa, Nicola Armaroli
1Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche , Via P. Gobetti 101, 40129 Bologna, Italy.
Inorganic Chemistry
|March 6, 2015
Summary
This study presents novel cationic iridium(III) complexes, isolating cis and trans isomers for the first time in this class. The cis isomer shows significantly enhanced photoluminescence quantum yield (PLQY) due to slower nonradiative decay, indicating potential for optoelectronic devices.
Area of Science:
- Organometallic Chemistry
- Materials Science
- Photophysics
Background:
- Iridium(III) complexes are crucial in optoelectronics.
- Bis(heteroleptic) iridium complexes with two cyclometalating ligands are rarely studied.
- Isomerism in such complexes can significantly impact photophysical properties.
Purpose of the Study:
- To synthesize and characterize novel cationic iridium(III) complexes with carbene-based ligands.
- To isolate and study the photophysical properties of cis and trans isomers.
- To explore their potential for optoelectronic applications.
Main Methods:
- Synthesis of cationic iridium(III) complexes.
- Characterization using NMR spectroscopy (1H, 13C, 31P) and HRMS (ESI-TOF).
- X-ray crystallography for structural determination.
- Cyclic voltammetry for electrochemical analysis.
- Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations.
- Temperature-dependent photoluminescence studies.
Main Results:
- Isolation of cis and trans isomers of bis(heteroleptic) iridium complexes for the first time.
- Complexes exhibit reversible redox processes, suitable for optoelectronics.
- The cis isomer shows a 4-fold increase in photoluminescence quantum yield (PLQY) in solution compared to the trans isomer.
- Calculations predict the blue shift observed in the cis isomer's spectra.
- Similar emission properties and high PLQY (~70-80%) observed in solid-state matrices for both isomers.
- Solvation effects are identified as the primary reason for nonradiative deactivation in trans complexes.
Conclusions:
- The successful isolation of cis and trans isomers opens new avenues for iridium complex design.
- The distinct photophysical properties of cis and trans isomers, particularly the higher PLQY of the cis form, are significant.
- These findings highlight the importance of isomer control for optimizing iridium complexes in optoelectronic applications.
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