New Photosensitizers Based on Heteroleptic Cu(I) Complexes and CO2 Photocatalytic Reduction with (Ni(II)(cyclam))Cl2
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Abstract
Summary
A photochemical reduction of CO2 was shown using the nickel catalyst Ni(cyclam)Cl2 and the copper-based photosensitizers 100906, 100907, 100908 and100909. Turnover numbers (TONs) of 8.1 for CO were reached in acetonitrile/TEOA for complex 100908 after 4 hours. Employing the other synthesized photosensitizers 100906, 100907 or 100909, TONs of 4.3 to 4.9 were obtained. The experiments were conducted under visible-light irradiation (λ = 420 nm) using BIH as sacrificial electron donor (see section SEDs below).
Advances and special progress
The first example of Cu(I)-based photosensitizers used for photocatalytic CO2 reduction in combination with Ni(cyclam)Cl2 was successfully reported, demonstrating the usability of a fully noble-metal free CO2 reduction system. The TONs are consistent with previously reported results on noble-metal based photosensitizers.
Additional remarks
The developed heteroleptic photosensitizer complexes showed a high stability in acetonitrile and no ligand release or formation of the homoleptic complexes was detected in UV/Vis stability studies.
Content of the published article in detail
The article contains results for the reduction of CO2 to CO under visible-light catalysis using a nickel complex as catalyst and copper-based photosensitizers. The catalytic system performs best (referring to the TON of CO production) in acetonitrile/TEOA with photosensitizer 100908.
Catalysts
Photosensitizers
Investigations
cat | cat conc [µM] | PS | PS conc [mM] | e-D | e-D conc [M] | solvent A | . | . | . | . | λexc [nm] | . | TON CO | . | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1. | 0.1 | 1 | 0.02 | 420 nm (4 x 8 W) | 4.3 | ||||||||||
2. | 0.1 | 1 | 0.02 | 420 nm (4 x 8 W) | 4.9 | ||||||||||
3. | 0.1 | 1 | 0.02 | 420 nm (4 x 8 W) | 8.1 | ||||||||||
4. | 0.1 | 1 | 0.02 | 420 nm (4 x 8 W) | 4.6 | ||||||||||
5. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | 2.6 | ||||||||||
6. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | 3.5 | ||||||||||
7. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | 5.0 | ||||||||||
8. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | 1.8 | ||||||||||
9. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | 2.8 | ||||||||||
10. | 1 | 0.01 | 420 nm (4 x 8 W) | ||||||||||||
11. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | |||||||||||
12. | 0.1 | 1 | 420 nm (4 x 8 W) | ||||||||||||
13. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | |||||||||||
14. | 0.1 | 0.01 | 420 nm (4 x 8 W) | ||||||||||||
15. | 0.1 | 1 | 0.01 | dark | |||||||||||
16. | 0.1 | 1 | 0.01 | 420 nm (4 x 8 W) | |||||||||||
17. | 0.1 | 1 | 0.02 | 420 nm (4 x 8 W) | 7.3 | ||||||||||
18. | 0.1 | 1 | 0.02 | 420 nm (4 x 8 W) | 6.5 |
Sacrificial Electron Donor
In this study, the experiments were done with the sacrificial electron donor BIH.
Additives
In this study, TEOA was used as a proton donor. For one experiment, N(Me)3 was employed instead. The catalyst [Cu(ACN)4][BF4] was used for a control experiment.
Investigations
- Photocatalytic CO2 reduction and control experiments (Molecular process, Photocatalytic CO2 conversion experiments)