Solid-State and Solution Metallophilic Aggregation of a Cationic [Pt(NCN)L](+) Cyclometalated Complex
Vasily V Sivchik1, Elena V Grachova, Alexei S Melnikov2
1Department of Chemistry, University of Eastern Finland , 80101 Joensuu, Finland.
Inorganic Chemistry
|March 12, 2016
Summary
The steric properties of ligands and counterions influence cyclometalated platinum complexes, affecting their aggregation, photoluminescence, and solid-state transformations. These interactions are temperature-dependent and concentration-controlled, enabling tunable emission colors.
Area of Science:
- Coordination Chemistry
- Photophysics
- Materials Science
Background:
- Cyclometalated platinum complexes exhibit intriguing intermolecular interactions like π-π stacking and metallophilic bonding.
- These interactions are crucial for determining the solid-state and solution properties of such complexes.
- Understanding these noncovalent forces is key to designing functional materials.
Purpose of the Study:
- To investigate the influence of ancillary ligands and counterions on the noncovalent interactions of cyclometalated platinum complexes.
- To explore the impact of these interactions on aggregation behavior and photoluminescent properties.
- To study the temperature and concentration dependence of these phenomena and their solid-state transformations.
Main Methods:
- Variable-temperature X-ray diffraction to analyze crystal structure and Pt···Pt interactions.
- Variable concentration NMR spectroscopy to study aggregation in solution.
- Photoluminescence spectroscopy to characterize emission properties.
- Time-dependent density functional theory (TD-DFT) calculations for theoretical support.
Main Results:
- Steric properties of ancillary ligands (L) dictate intermolecular interactions in both solid and solution states.
- Counterions (X-) influence the crystal packing of the complexes.
- Complexes form temperature-dependent Pt···Pt interactions and π-stacking.
- In solution, complexes aggregate at higher concentrations, forming ground-state oligomers.
- Photoluminescence is strongly influenced by aggregation, with oligomers showing red-shifted emission.
- Solid-state transformations triggered by vapor lead to reversible changes in molecular structure and photophysical properties.
Conclusions:
- Noncovalent interactions in cyclometalated platinum complexes are tunable via ligand and counterion choice.
- Aggregation plays a critical role in modulating photoluminescent properties, allowing for color tuning.
- Reversible solid-state transformations offer pathways for dynamic material design.
- TD-DFT calculations provide valuable insights into the observed experimental phenomena.
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