Synergistic Porosity and Charge Effects in a Supramolecular Porphyrin Cage Promote Efficient Photocatalytic CO 2 Reduction

We present a supramolecular approach to catalyzing photochemical CO reduction through second-sphere porosity and charge effects. An iron porphyrin box (PB) bearing 24 cationic groups, FePB-2(P), was made via post-synthetic modification of an alkyne-functionalized supramolecular synthon. FePB-2(P) pr...

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Published inAngewandte Chemie International Edition Vol. 62; no. 5; p. e202209396
Main Authors An, Lun, De La Torre, Patricia, Smith, Peter T, Narouz, Mina R, Chang, Christopher J
Format Journal Article
LanguageEnglish
Published Germany 26.01.2023
Subjects
Electrocatalysis
Carbon Dioxide Reduction
Second-Sphere
Photocatalysis
Porous Cage
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Summary:We present a supramolecular approach to catalyzing photochemical CO reduction through second-sphere porosity and charge effects. An iron porphyrin box (PB) bearing 24 cationic groups, FePB-2(P), was made via post-synthetic modification of an alkyne-functionalized supramolecular synthon. FePB-2(P) promotes the photochemical CO reduction reaction (CO RR) with 97 % selectivity for CO product, achieving turnover numbers (TON) exceeding 7000 and initial turnover frequencies (TOF ) reaching 1400 min . The cooperativity between porosity and charge results in a 41-fold increase in activity relative to the parent Fe tetraphenylporphyrin (FeTPP) catalyst, which is far greater than analogs that augment catalysis through porosity (FePB-3(N), 4-fold increase) or charge (Fe p-tetramethylanilinium porphyrin (Fe-p-TMA), 6-fold increase) alone. This work establishes that synergistic pendants in the secondary coordination sphere can be leveraged as a design element to augment catalysis at primary active sites within confined spaces.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202209396