Editing Light-Driven Reduction of CO2 to CO in Water with a Cobalt Molecular Catalyst and an Organic Sensitizer

{{DOI|doi=10.1021/acscatal.3c00036}}
[[Category:Homogeneous photocatalytic CO2 conversion]]
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=== Abstract ===

==== Summary ====
A photochemical reduction of CO<sub>2</sub> to CO was shown using the cobalt complex {{#moleculelink:|link=OZQYFMFOIFRRLI-UHFFFAOYSA-L|image=false|width=300|height=200}} as a catalyst in combination with the organic, water soluble triazatriangulenium photosensitizer {{#moleculelink:|link=DORDHQADTWICIT-UHFFFAOYSA-N|image=false|width=300|height=200}}. Turnover numbers (TONs) up to 19000 and selectivity of 93% for CO were reached in acetonitrile with 20% of water. The experiments were conducted under visible-light irradiation (λ > 450 nm) using tertiary amines or BIH as sacrificial reductants (see section SEDs below). The photoreduction could also be shown in pure water.

==== Advances and special progress ====
The photoreduction of CO<sub>2</sub> to CO could be shown in 100% water with a TON of 2600 and a selectivity of 94% without any noble metals or rare materials.

==== Additional remarks ====
In initial experiments, CO and formate were first produced with a total TON >3700 upon irradiation in CO<sub>2</sub>-saturated CH<sub>3</sub>CN solution with visible light. The addition of water enhanced the catalysis and directed it toward CO production (19,000 TON, 93% selectivity). 

=== Content of the published article in detail ===
The article contains results for the reduction of CO<sub>2</sub> to CO under visible-light catalysis using a cobalt complex as a catalyst. The catalytic system performs best (referring to the TON of CO production) in acetonitrile with 20% water using BIH and TEOA. 

==== Catalyst ====
<chemform smiles="C1C2C3C=CC=C4C5C=CC=C6C7C=CC=CN=7[Co+2](O)(O)(N=34)(N=56)N=2C=CC=1.Cl([O-])(=O)(=O)=O.Cl([O-])(=O)(=O)=O" inchi="1S/C20H14N4.2ClHO4.Co.2H2O/c1-3-13-21-15(7-1)17-9-5-11-19(23-17)20-12-6-10-18(24-20)16-8-2-4-14-22-16;2*2-1(3,4)5;;;/h1-14H;2*(H,2,3,4,5);;2*1H2/q;;;+2;;/p-2" inchikey="OZQYFMFOIFRRLI-UHFFFAOYSA-L" height="200px" width="300px" float="none"></chemform><chemform smiles="[Co+2]([Cl-])[Cl-]" inchi="1S/2ClH.Co/h2*1H;/q;;+2/p-2" inchikey="GVPFVAHMJGGAJG-UHFFFAOYSA-L" height="200px" width="300px" float="none">
  -INDIGO-11172313372D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 3 2 0 0 0
M  V30 BEGIN ATOM
M  V30 1 Co 9.475 -6.35 0.0 0 CHG=2
M  V30 2 Cl 10.1821 -7.05711 0.0 0 CHG=-1
M  V30 3 Cl 9.73382 -5.38407 0.0 0 CHG=-1
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 1 1 2
M  V30 2 1 1 3
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform>

==== Photosensitizer ====
<chemform smiles="C12C3N(CCCC)C4C5[C+]1C1C(N(CCCC)C=5C=CC=4)=CC=CC=1N(CCCC)C=2C=CC=3.[P-](F)(F)(F)(F)(F)F" inchi="1S/C31H36N3.F6P/c1-4-7-19-32-22-13-10-15-24-28(22)31-29-23(32)14-11-16-25(29)34(21-9-6-3)27-18-12-17-26(30(27)31)33(24)20-8-5-2;1-7(2,3,4,5)6/h10-18H,4-9,19-21H2,1-3H3;/q+1;-1" inchikey="DORDHQADTWICIT-UHFFFAOYSA-N" height="200px" width="300px" float="none">
  -INDIGO-11172313202D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 41 45 0 0 0
M  V30 BEGIN ATOM
M  V30 1 C 3.25899 -8.02499 0.0 0
M  V30 2 C 3.25899 -9.02501 0.0 0
M  V30 3 N 4.125 -9.52501 0.0 0
M  V30 4 C 4.99101 -9.02501 0.0 0
M  V30 5 C 4.99101 -8.02499 0.0 0
M  V30 6 C 4.125 -7.52499 0.0 0 CHG=1
M  V30 7 C 2.39529 -9.52292 0.0 0
M  V30 8 C 1.52891 -9.02305 0.0 0
M  V30 9 C 2.38914 -7.52312 0.0 0
M  V30 10 C 1.52671 -8.02806 0.0 0
M  V30 11 C 5.85471 -7.52708 0.0 0
M  V30 12 C 6.72109 -8.02695 0.0 0
M  V30 13 C 5.86086 -9.52688 0.0 0
M  V30 14 C 6.72329 -9.02194 0.0 0
M  V30 15 C 4.125 -10.525 0.0 0
M  V30 16 C 3.25897 -11.025 0.0 0
M  V30 17 C 3.25897 -12.025 0.0 0
M  V30 18 C 2.39295 -12.525 0.0 0
M  V30 19 N 5.85536 -6.53012 0.0 0
M  V30 20 C 4.99232 -6.03107 0.0 0
M  V30 21 C 4.12863 -6.52899 0.0 0
M  V30 22 C 3.25846 -6.01651 0.0 0
M  V30 23 N 2.38888 -6.51888 0.0 0
M  V30 24 C 3.2689 -5.03378 0.0 0
M  V30 25 C 4.99268 -5.02992 0.0 0
M  V30 26 C 4.12716 -4.53647 0.0 0
M  V30 27 C 6.72172 -6.03069 0.0 0
M  V30 28 C 7.58741 -6.53127 0.0 0
M  V30 29 C 8.45377 -6.03184 0.0 0
M  V30 30 C 9.31946 -6.53241 0.0 0
M  V30 31 C 1.52272 -6.01911 0.0 0
M  V30 32 C 1.52245 -5.01911 0.0 0
M  V30 33 C 0.65629 -4.51935 0.0 0
M  V30 34 C 0.656021 -3.51935 0.0 0
M  V30 35 P 14.125 -6.75 0.0 0 CHG=-1
M  V30 36 F 14.3838 -7.71593 0.0 0
M  V30 37 F 14.8321 -6.04289 0.0 0
M  V30 38 F 13.1591 -6.49118 0.0 0
M  V30 39 F 13.8662 -5.78407 0.0 0
M  V30 40 F 15.0909 -7.00882 0.0 0
M  V30 41 F 13.4179 -7.45711 0.0 0
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 1 1 6
M  V30 2 2 1 2
M  V30 3 1 2 3
M  V30 4 1 3 4
M  V30 5 2 4 5
M  V30 6 1 5 6
M  V30 7 2 8 7
M  V30 8 1 1 9
M  V30 9 1 7 2
M  V30 10 2 9 10
M  V30 11 1 10 8
M  V30 12 2 12 11
M  V30 13 1 4 13
M  V30 14 1 11 5
M  V30 15 2 13 14
M  V30 16 1 14 12
M  V30 17 1 3 15
M  V30 18 1 15 16
M  V30 19 1 16 17
M  V30 20 1 17 18
M  V30 21 1 11 19
M  V30 22 1 19 20
M  V30 23 2 20 21
M  V30 24 1 21 6
M  V30 25 1 22 23
M  V30 26 1 23 9
M  V30 27 2 24 22
M  V30 28 1 20 25
M  V30 29 2 25 26
M  V30 30 1 26 24
M  V30 31 1 22 21
M  V30 32 1 19 27
M  V30 33 1 27 28
M  V30 34 1 28 29
M  V30 35 1 29 30
M  V30 36 1 23 31
M  V30 37 1 31 32
M  V30 38 1 32 33
M  V30 39 1 33 34
M  V30 40 1 35 36
M  V30 41 1 35 37
M  V30 42 1 35 38
M  V30 43 1 35 39
M  V30 44 1 35 40
M  V30 45 1 35 41
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform>

==== Investigations ====
{{#experimentlist:|form=Photocatalytic_CO2_conversion_experiments|name=Visible-Light Driven CO2 Reduction with 1/TATA+/BIH + TEOA under Various Conditions|importFile=}}

{{#experimentlist:|form=Photocatalytic_CO2_conversion_experiments|name=Photocatalytic CO2 Reduction by 1 (2 μM) in CO2-Saturated Aqueous CH3CN Solutions|importFile=}}

==== Sacrificial electron donor ====
In this study, the experiments were done with the sacrificial reductants TEOA ([[Molecule:100507|100507]]), BIH ([[Molecule:100508|100508]]), and TEA ([[Molecule:100505|100505]]).

==== Additives ====
In this study, some experiments were conducted under argon atmosphere or with the addition of Hg.