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Quantifying the Binding Interactions Between Cu(II) and Peptide Residues in the Presence and Absence of Chromophores
Published on: April 5, 2022
Matrix effects on copper(II)phthalocyanine complexes. A combined continuous wave and pulse EPR and DFT study
Cinzia Finazzo1, Carlos Calle, Stefan Stoll
1Physical Chemistry Laboratory, ETH Zurich, 8093, Zurich, Switzerland.
Physical Chemistry Chemical Physics : PCCP
|April 25, 2006
Summary
The electronic structure of copper phthalocyanines is sensitive to solvent polarity and peripheral groups. Electron paramagnetic resonance reveals changes in metal-ligand bonding, with tert-butyl groups increasing covalency in nonpolar solvents.
Area of Science:
- Coordination Chemistry
- Physical Chemistry
- Spectroscopy
Background:
- The redox chemistry of metal phthalocyanines is influenced by substituent effects and solvent polarity.
- Understanding the electronic structure of copper phthalocyanines is crucial for their applications.
Purpose of the Study:
- To investigate the electronic structure of copper phthalocyanine (CuPc), CuPc(t), and CuPc(F) complexes.
- To determine the influence of peripheral groups and solvent polarity on the electronic and bonding properties.
Main Methods:
- Continuous wave and pulse electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectroscopy.
- Isotope substitutions for detailed spectral analysis.
- Density functional theory (DFT) computations for parameter interpretation.
Main Results:
- EPR parameters (g values, hyperfine couplings) are sensitive to solvent and macrocycle structure.
- In-plane metal-ligand sigma bonding is more covalent in CuPc(t) in toluene than in sulfuric acid.
- Out-of-plane pi bonding covalency increases with tert-butyl groups and is higher in nonpolar solvents.
Conclusions:
- Solvent polarity and peripheral substituents significantly modulate the electronic structure and bonding in copper phthalocyanines.
- DFT computations aid in interpreting EPR data and understanding bonding characteristics.
- The study provides insights into the structure-property relationships of phthalocyanine complexes.
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