Bioinspired, Multidisciplinary, Iterative Catalyst Design Creates the Highest Performance Peroxidase Mimics and the Field of Sustainable Ultradilute Oxidation Catalysis (SUDOC)

• Published in: ACS catalysis 2019-08, Vol.9 (8), p.7023-7037
• Main Authors: Warner, Genoa R, Somasundar, Yogesh, Jansen, Kyle C, Kaaret, Evan Z, Weng, Cindy, Burton, Abigail E, Mills, Matthew R, Shen, Longzhu Q, Ryabov, Alexander D, Pros, Gabrielle, Pintauer, Tomislav, Biswas, Saborni, Hendrich, Michael P, Taylor, Julia A, Vom Saal, Frederick S, Collins, Terrence J
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.9b01409

Oxidation catalysts called NewTAMLs, macrocyclic complexes with TAML carbonamido-N donors replaced by more nucleophile-resistant binders, sulfonamido-N, for example, [Fe­{4-NO2C6H3-1,2-(NCOCMe2 NSO2)2CHMe}]− (5d), deliver record-setting technical performance parameters (TPPs) for functional peroxidase mimicry. NewTAMLs were designed to test the previously discounted hypothesis that nucleophilic decay of carbonamido-N iron chelators is TAML catalyst lifetime-limiting and, for precautionary reasons, to escape fluorine in the best-performing TAML (1c) for catalyzing ultradilute water purification by H2O2. Replacing two of four TAML carbonamides with less σ-donating sulfonamides in 5 was found to more than compensate for eliminating 1c’s F-substituents to increase substrate oxidation rates and, following the discovery and parametrization of an additional decomposition mechanism, to alter catalyst degradation rates protectively. At pH 7 in less than 5 min, the best-performing NewTAML 5d activates H2O2 to eliminate the β-blocker drug and sentinel micropollutant (MP) propranolol to the limit of UPLC detection under very dilute starting conditions that pass through the ultradilute regime (≤2 ppb): [5d] = 100 nM (∼60 ppb), [propranolol] = 53 nM (15.6 ppb), [H2O2] = 330 μM (11.2 ppm). This is ca. 10 times faster than 1c/H2O2 under comparable conditions giving an important advance in the real-world potential for time-, concentration-, and cost-sensitive MP water treatments. The separate decomposition mechanism involves carbon acids bridging the two sulfonamides, a discovery that expands design control over operating NewTAML lifetimesthese features we have named “kill switches” are analyzed for impacts on catalytic function, process control, and sustainable design. Mouse uterotrophic assays show no low-dose adverse effects (lodafs) for the prototype NewTAML (5a) or for the process solution from the 5a/H2O2 destruction of the contraceptive pill estrogen, ethinyl estradiol (EE2), a potent MP. The multidisciplinary catalyst design protocol that led to NewTAMLs is presented graphically to highlight how five key sustainability performancestechnical, cost, health, environmental, fairnessare being optimized together for sustainable oxidation catalysis and water treatment. The results validate the “bioinspired” descriptor and the name sustainable ultradilute oxidation catalysis (SUDOC) for this emerging field while highlighting to chemists that dealing with the lodafs and