Editing Highly Efficient and Selective Photocatalytic CO2 Reduction by Iron and Cobalt Quaterpyridine Complexes

{{#doiinfobox: 10.1021/jacs.6b06002}} 
[[Category:Photocatalytic CO2 conversion to CO]]
{{BaseTemplate}}

===Abstract===
====Summary====
A photochemical reduction of CO<sub>2</sub> to CO was shown using the cobalt complex {{#moleculelink:|link=NLKWUAXOGCKGEY-UHFFFAOYSA-L|image=false|width=300|height=200}} or the iron complex {{#moleculelink:|link=OZQYFMFOIFRRLI-UHFFFAOYSA-L|image=false|width=300|height=200}} as catalysts in combination with the ruthenium-based photosensitizer {{#moleculelink:|link=SJFYGUKHUNLZTK-UHFFFAOYSA-L|image=false|width=300|height=200}}. Turnover numbers (TONs) up to 2660 and a selectivity of 98% for CO using the cobalt catalyst and TONs of >3000 and a selectivity of 95% for CO using the iron catalyst were reached in acetonitrile/triethanolamine. When swapping the ruthenium photosensitizer for the organic dye sensitizer {{#moleculelink:|link=BBNQQADTFFCFGB-UHFFFAOYSA-N|image=false|width=300|height=200}}, TONs of 790 and 1365 in DMF were obtained for the cobalt and iron catalysts, respectively. The experiments were conducted under visible-light irradiation (λ = 460 nm) using BIH as sacrificial reductant (see section SEDs below).  
==== Advances and special progress====
The photocatalytic reduction of CO<sub>2</sub> to CO by cobalt and iron complexes was shown with some of the highest TONs for homogeneous photocatalytic CO2 reduction at that time and the (back then) highest TON for a system of fully earth-abundant materials was achieved.

====Additional remarks====
===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 cobalt and iron quaterpyridine complexes as catalysts. The catalytic system performs best (referring to the TON of CO production) in acetonitrile/triethanolamine using the cobalt complex and the ruthenium photosensitizer. 
==== Catalysts ====
<chemform smiles="C1C2C3C=CC=C4C5C=CC=C6C7C=CC=CN=7[Fe+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.Fe.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="NLKWUAXOGCKGEY-UHFFFAOYSA-L" height="200px" width="300px" float="none">
  -INDIGO-08112312532D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 37 41 0 0 0
M  V30 BEGIN ATOM
M  V30 1 C 6.83485 -2.97507 0.0 0
M  V30 2 C 8.56515 -2.97459 0.0 0
M  V30 3 C 7.70164 -2.47497 0.0 0
M  V30 4 C 8.56515 -3.97553 0.0 0
M  V30 5 C 6.83485 -3.98002 0.0 0
M  V30 6 N 7.70382 -4.47503 0.0 0
M  V30 7 C 5.97028 -4.48253 0.0 0
M  V30 8 C 5.1109 -5.98433 0.0 0
M  V30 9 N 5.97356 -5.48323 0.0 0
M  V30 10 C 4.24227 -5.48695 0.0 0
M  V30 11 C 5.09818 -3.98316 0.0 0
M  V30 12 C 4.23681 -4.49128 0.0 0
M  V30 13 C 5.114 -6.98432 0.0 0
M  V30 14 C 5.98521 -8.47929 0.0 0
M  V30 15 N 5.98238 -7.48166 0.0 0
M  V30 16 C 5.12026 -8.98303 0.0 0
M  V30 17 C 4.24559 -7.49007 0.0 0
M  V30 18 C 4.25515 -8.4901 0.0 0
M  V30 19 C 6.85288 -8.97643 0.0 0
M  V30 20 C 8.58317 -8.96906 0.0 0
M  V30 21 N 7.71768 -8.47288 0.0 0
M  V30 22 C 8.58715 -9.97 0.0 0
M  V30 23 C 6.85688 -9.98136 0.0 0
M  V30 24 C 7.72781 -10.4729 0.0 0
M  V30 25 Fe 7.72882 -6.42503 0.0 0 CHG=2
M  V30 26 O 9.04485 -5.57503 0.0 0
M  V30 27 O 9.11985 -7.27503 0.0 0
M  V30 28 Cl 11.8 -4.275 0.0 0
M  V30 29 O 10.8 -4.275 0.0 0
M  V30 30 O 11.8088 -3.28407 0.0 0
M  V30 31 O 12.8659 -4.28382 0.0 0
M  V30 32 O 11.8 -5.275 0.0 0 CHG=-1
M  V30 33 Cl 11.88 -7.54538 0.0 0
M  V30 34 O 10.8629 -7.54538 0.0 0
M  V30 35 O 11.889 -6.53745 0.0 0
M  V30 36 O 12.8621 -7.55478 0.0 0
M  V30 37 O 11.88 -8.56255 0.0 0 CHG=-1
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 2 3 1
M  V30 2 2 4 2
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M  V30 4 1 2 3
M  V30 5 2 5 6
M  V30 6 1 6 4
M  V30 7 1 5 7
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M  V30 17 1 13 17
M  V30 18 1 14 15
M  V30 19 2 17 18
M  V30 20 1 18 16
M  V30 21 1 14 19
M  V30 22 2 21 19
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M  V30 24 1 19 23
M  V30 25 1 20 21
M  V30 26 2 23 24
M  V30 27 1 24 22
M  V30 28 10 6 25
M  V30 29 10 25 21
M  V30 30 10 15 25
M  V30 31 10 25 9
M  V30 32 10 25 26
M  V30 33 10 25 27
M  V30 34 2 28 29
M  V30 35 2 28 30
M  V30 36 2 28 31
M  V30 37 1 28 32
M  V30 38 2 33 34
M  V30 39 2 33 35
M  V30 40 2 33 36
M  V30 41 1 33 37
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform><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">
  -INDIGO-08112312532D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 37 41 0 0 0
M  V30 BEGIN ATOM
M  V30 1 C 7.93029 25.0727 0.0 0
M  V30 2 C 9.46221 25.0731 0.0 0
M  V30 3 C 8.6977 25.5155 0.0 0
M  V30 4 C 9.46221 24.187 0.0 0
M  V30 5 C 7.93029 24.183 0.0 0
M  V30 6 N 8.69963 23.7447 0.0 0
M  V30 7 C 7.16484 23.7381 0.0 0
M  V30 8 C 6.40399 22.4085 0.0 0
M  V30 9 N 7.16775 22.8521 0.0 0
M  V30 10 C 5.63495 22.8488 0.0 0
M  V30 11 C 6.39273 24.1802 0.0 0
M  V30 12 C 5.63011 23.7303 0.0 0
M  V30 13 C 6.40673 21.5231 0.0 0
M  V30 14 C 7.17806 20.1996 0.0 0
M  V30 15 N 7.17556 21.0828 0.0 0
M  V30 16 C 6.41228 19.7536 0.0 0
M  V30 17 C 5.63789 21.0754 0.0 0
M  V30 18 C 5.64635 20.19 0.0 0
M  V30 19 C 7.94625 19.7594 0.0 0
M  V30 20 C 9.47817 19.7659 0.0 0
M  V30 21 N 8.7119 20.2052 0.0 0
M  V30 22 C 9.48169 18.8798 0.0 0
M  V30 23 C 7.94979 18.8697 0.0 0
M  V30 24 C 8.72087 18.4345 0.0 0
M  V30 25 Co 8.72177 22.0183 0.0 0 CHG=2
M  V30 26 O 9.88692 22.7708 0.0 0
M  V30 27 O 9.95332 21.2657 0.0 0
M  V30 28 Cl 12.3262 23.9218 0.0 0
M  V30 29 O 11.4408 23.9218 0.0 0
M  V30 30 O 12.334 24.7992 0.0 0
M  V30 31 O 13.2699 23.914 0.0 0
M  V30 32 O 12.3262 23.0365 0.0 0 CHG=-1
M  V30 33 Cl 12.397 21.0264 0.0 0
M  V30 34 O 11.4965 21.0264 0.0 0
M  V30 35 O 12.405 21.9188 0.0 0
M  V30 36 O 13.2665 21.0181 0.0 0
M  V30 37 O 12.397 20.1258 0.0 0 CHG=-1
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 2 3 1
M  V30 2 2 4 2
M  V30 3 1 1 5
M  V30 4 1 2 3
M  V30 5 2 5 6
M  V30 6 1 6 4
M  V30 7 1 5 7
M  V30 8 2 9 7
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M  V30 13 1 12 10
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M  V30 15 2 15 13
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M  V30 17 1 13 17
M  V30 18 1 14 15
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M  V30 20 1 18 16
M  V30 21 1 14 19
M  V30 22 2 21 19
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M  V30 24 1 19 23
M  V30 25 1 20 21
M  V30 26 2 23 24
M  V30 27 1 24 22
M  V30 28 10 6 25
M  V30 29 10 25 21
M  V30 30 10 15 25
M  V30 31 10 25 9
M  V30 32 10 25 26
M  V30 33 10 25 27
M  V30 34 2 28 29
M  V30 35 2 28 30
M  V30 36 2 28 31
M  V30 37 1 28 32
M  V30 38 2 33 34
M  V30 39 2 33 35
M  V30 40 2 33 36
M  V30 41 1 33 37
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform><chemform smiles="Cl([O-])(=O)(=O)=O.Cl([O-])(=O)(=O)=O.[Co+2]" inchi="1S/2ClHO4.Co/c2*2-1(3,4)5;/h2*(H,2,3,4,5);/q;;+2/p-2" inchikey="BSUSEPIPTZNHMN-UHFFFAOYSA-L" height="200px" width="300px" float="none">
  -INDIGO-08112313202D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 11 8 0 0 0
M  V30 BEGIN ATOM
M  V30 1 Cl 5.85991 -4.47939 0.0 0
M  V30 2 O 5.02832 -4.47939 0.0 0
M  V30 3 O 5.86723 -3.65532 0.0 0
M  V30 4 O 6.74625 -4.48672 0.0 0
M  V30 5 O 5.85991 -5.31088 0.0 0 CHG=-1
M  V30 6 Cl 10.3764 -4.54882 0.0 0
M  V30 7 O 9.53063 -4.54882 0.0 0
M  V30 8 O 10.3839 -3.71065 0.0 0
M  V30 9 O 11.1931 -4.55661 0.0 0
M  V30 10 O 10.3764 -5.39468 0.0 0 CHG=-1
M  V30 11 Co 7.8 -4.45 0.0 0 CHG=2
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 2 1 2
M  V30 2 2 1 3
M  V30 3 2 1 4
M  V30 4 1 1 5
M  V30 5 2 6 7
M  V30 6 2 6 8
M  V30 7 2 6 9
M  V30 8 1 6 10
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform>

==== Photosensitizers ====
<chemform smiles="C1C2C3C=CC=CN=3[Ru+2]3(N4C=CC=CC=4C4N3=CC=CC=4)3(N4C=CC=CC=4C4N3=CC=CC=4)N=2C=CC=1.[Cl-].[Cl-]" inchi="1S/3C10H8N2.2ClH.Ru/c3*1-3-7-11-9(5-1)10-6-2-4-8-12-10;;;/h3*1-8H;2*1H;/q;;;;;+2/p-2" inchikey="SJFYGUKHUNLZTK-UHFFFAOYSA-L" height="200px" width="300px" float="none">
  -INDIGO-08112312492D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 39 45 0 0 0
M  V30 BEGIN ATOM
M  V30 1 C 7.18485 -2.40007 0.0 0
M  V30 2 C 8.91515 -2.39959 0.0 0
M  V30 3 C 8.05164 -1.89997 0.0 0
M  V30 4 C 8.91515 -3.40053 0.0 0
M  V30 5 C 7.18485 -3.40502 0.0 0
M  V30 6 N 8.05382 -3.90003 0.0 0
M  V30 7 C 6.32028 -3.90753 0.0 0
M  V30 8 C 5.4609 -5.40933 0.0 0
M  V30 9 N 6.32356 -4.90824 0.0 0
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M  V30 17 C 4.59559 -6.91507 0.0 0
M  V30 18 C 4.60515 -7.9151 0.0 0
M  V30 19 C 7.20288 -8.40143 0.0 0
M  V30 20 C 8.93317 -8.39406 0.0 0
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M  V30 24 C 8.07781 -9.89792 0.0 0
M  V30 25 C 9.79743 -7.89102 0.0 0
M  V30 26 C 10.6559 -6.38869 0.0 0
M  V30 27 N 9.79354 -6.89032 0.0 0
M  V30 28 C 11.5248 -6.88554 0.0 0
M  V30 29 C 10.6698 -8.38985 0.0 0
M  V30 30 C 11.5309 -7.8812 0.0 0
M  V30 31 C 10.6522 -5.3887 0.0 0
M  V30 32 C 9.78004 -3.89427 0.0 0
M  V30 33 N 9.78349 -4.8919 0.0 0
M  V30 34 C 10.6447 -3.39 0.0 0
M  V30 35 C 11.5203 -4.88241 0.0 0
M  V30 36 C 11.5101 -3.88239 0.0 0
M  V30 37 Ru 8.05382 -5.85003 0.0 0 CHG=2
M  V30 38 Cl 10.05 -2.325 0.0 0 CHG=-1
M  V30 39 Cl 3.975 -5.9 0.0 0 CHG=-1
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 2 3 1
M  V30 2 2 4 2
M  V30 3 1 1 5
M  V30 4 1 2 3
M  V30 5 2 5 6
M  V30 6 1 6 4
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M  V30 9 2 10 8
M  V30 10 1 7 11
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M  V30 13 1 12 10
M  V30 14 2 15 13
M  V30 15 2 16 14
M  V30 16 1 13 17
M  V30 17 1 14 15
M  V30 18 2 17 18
M  V30 19 1 18 16
M  V30 20 1 14 19
M  V30 21 2 21 19
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M  V30 25 2 23 24
M  V30 26 1 24 22
M  V30 27 2 27 25
M  V30 28 2 28 26
M  V30 29 1 25 29
M  V30 30 1 26 27
M  V30 31 2 29 30
M  V30 32 1 30 28
M  V30 33 1 26 31
M  V30 34 2 33 31
M  V30 35 2 34 32
M  V30 36 1 31 35
M  V30 37 1 32 33
M  V30 38 2 35 36
M  V30 39 1 36 34
M  V30 40 10 6 37
M  V30 41 10 37 9
M  V30 42 10 15 37
M  V30 43 10 37 21
M  V30 44 10 27 37
M  V30 45 10 37 33
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform><chemform smiles="C1C=CC2C(=O)C3C(O)=CC(O)=C(O)C=3C(=O)C=2C=1" inchi="1S/C14H8O5/c15-8-5-9(16)14(19)11-10(8)12(17)6-3-1-2-4-7(6)13(11)18/h1-5,15-16,19H" inchikey="BBNQQADTFFCFGB-UHFFFAOYSA-N" height="200px" width="300px" float="none">
  -INDIGO-08112312542D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 19 21 0 0 0
M  V30 BEGIN ATOM
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M  V30 5 C 5.30985 -6.43002 0.0 0
M  V30 6 C 6.17882 -6.92503 0.0 0
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M  V30 9 C 7.9108 -6.92787 0.0 0
M  V30 10 C 8.77403 -6.42246 0.0 0
M  V30 11 C 9.63088 -4.92878 0.0 0
M  V30 12 C 10.4948 -5.42469 0.0 0
M  V30 13 C 9.64141 -6.92035 0.0 0
M  V30 14 C 10.4992 -6.41559 0.0 0
M  V30 15 O 7.90482 -3.92621 0.0 0
M  V30 16 O 7.91399 -7.92786 0.0 0
M  V30 17 O 9.62885 -3.92878 0.0 0
M  V30 18 O 11.3591 -4.92169 0.0 0
M  V30 19 O 9.64681 -7.92034 0.0 0
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 2 3 1
M  V30 2 2 4 2
M  V30 3 1 1 5
M  V30 4 1 2 3
M  V30 5 2 5 6
M  V30 6 1 6 4
M  V30 7 1 8 7
M  V30 8 1 4 9
M  V30 9 1 7 2
M  V30 10 1 9 10
M  V30 11 2 10 8
M  V30 12 2 12 11
M  V30 13 1 10 13
M  V30 14 1 11 8
M  V30 15 2 13 14
M  V30 16 1 14 12
M  V30 17 2 7 15
M  V30 18 2 9 16
M  V30 19 1 11 17
M  V30 20 1 12 18
M  V30 21 1 13 19
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform>

==== Investigations ====

{{#experimentlist: |form=Photocatalytic_CO2_conversion_experiments|name=Optimizations of conditions for Co(qpy)(H2O)2(ClO4)2 and Ru(bpy)3Cl2}}

{{#experimentlist: |form=Photocatalytic_CO2_conversion_experiments|name=Optimizations of conditions for Fe(qpy)(H2O)2(ClO4)2 and Ru(bpy)3Cl2}}

{{#experimentlist: |form=Photocatalytic_CO2_conversion_experiments|name=Optimizations of conditions for Co(qpy)(H2O)2(ClO4)2 and purpurin}}

{{#experimentlist:|form=Photocatalytic_CO2_conversion_experiments|name=Fe(qpy)(H2O)2(ClO4)2}}

==== Sacrificial electron donor ====
In this study, the experiments were done with the sacrificial reductant BIH ([[Molecule:100508|100508]]).
==== Additives====
In this study, control experiments were conducted under an argon atmosphere.