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[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
Monopicolinate cyclen and cyclam derivatives for stable copper(II) complexation
Luís M P Lima1, David Esteban-Gómez, Rita Delgado
1Université de Bretagne Occidentale, UMR-CNRS 6521, UFR des Sciences et Techniques, 6 avenue Victor le Gorgeu, C.S. 93837, 29238 Brest Cedex 3, France.
Inorganic Chemistry
|June 2, 2012
Summary
The cyclam-based ligand HL2 forms highly stable copper(II) complexes with fast complexation, excellent kinetic inertness, and strong thermodynamic and electrochemical stability, making it an attractive copper(II) receptor.
Area of Science:
- Coordination Chemistry
- Supramolecular Chemistry
- Macrocyclic Ligand Design
Background:
- Development of selective macrocyclic ligands for metal ion complexation is crucial in various chemical applications.
- 1,4,7,10-tetraazacyclododecane (cyclen) and 1,4,8,11-tetraazacyclotetradecane (cyclam) derivatives are widely studied for their coordination properties.
- Understanding the stability and reactivity of copper(II) complexes with novel ligands is essential for potential applications.
Purpose of the Study:
- To synthesize and characterize new cyclen and cyclam derivatives with picolinate pendant arms (HL1 and HL2).
- To investigate the acid-base properties and coordination chemistry of HL1 and HL2, particularly with Cu(2+).
- To evaluate the thermodynamic stability, kinetic inertness, and electrochemical behavior of the resulting copper(II) complexes.
Main Methods:
- Selective protection strategies were employed for the synthesis of cyclen-bisaminal and phosphoryl cyclam derivatives.
- Potentiometric titrations were used to determine stability constants of Cu(2+) complexes.
- Single crystal X-ray diffraction, UV-visible spectroscopy, electron paramagnetic resonance (EPR), and cyclic voltammetry were utilized for structural and electrochemical analysis.
Main Results:
- Both HL1 and HL2 ligands form thermodynamically stable and selective complexes with Cu(2+) over Zn(2+).
- The cyclam-based ligand HL2 forms a copper(II) complex ([CuL2](+)) exhibiting significantly higher kinetic inertness in acidic media compared to the cyclen analogue ([CuL1](+)).
- Crystallographic and spectroscopic data confirmed the coordination geometry, and electrochemical studies indicated good stability of the complexes upon Cu(2+) reduction.
Conclusions:
- The synthesized macrocyclic ligands HL1 and HL2 effectively complex Cu(2+), with protonation occurring on the picolinate carboxylate group.
- The cyclam-based ligand HL2 is identified as a superior receptor for Cu(2+), demonstrating rapid complexation, exceptional kinetic inertness, and robust thermodynamic and electrochemical stability.
- These findings highlight the potential of HL2 as a highly stable and selective copper(II) chelator for various applications.
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