Modeling the Enzyme Specificity by Molecular Cages through Regulating Reactive Oxygen Species Evolution

Abstract

Mimicking the active site and the substrate binding cavity of the enzyme to achieve specificity in catalytic reactions is an essential challenge. Herein, porous coordination cages (PCCs) with intrinsic cavities and tunable metal centers have proved the regulation of reactive oxygen species (ROS) generating pathways as evidenced by multiple photo-induced oxidations. Remarkably, in the presence of the Zn 4 -μ 4 -O center, PCC converted dioxygen molecules from triplet to singlet excitons, whereas the Ni 4 -μ 4 -O center promoted the efficient dissociation of electrons and holes to conduct electron transfer towards substrates. Accordingly, the distinct ROS generation behavior of PCC-6-Zn and PCC-6-Ni enables the conversion of O 2 to 1 O 2 and O 2 *À , respectively. In contrast, the Co 4 -μ 4 -O center combined the 1 O 2 and O 2 *Àtogether to generate carbonyl radicals, which in turn reacted with the oxygen molecules. Harnessing the three oxygen activation pathways, PCC-6-M (M = Zn/Ni/Co) display specific catalytic activities in thioanisole oxidation (PCC-6-Zn), benzylamine coupling (PCC-6-Ni), and aldehyde autoxidation (PCC-6-Co). This work not only provides fundamental insights into the regulation of ROS generation by a supramolecular catalyst but also demonstrates a rare example of achieving reaction specificity through mimicking natural enzymes by PCCs.

Ionic porous porphyrin cage as a superior catalyst for photocatalytic oxidization

“…After correction versus the normal hydrogen electrode (NHE, pH 6.8), the conduction band ( E CB ) was calculated to be −1.51 and −0.71 eV for TPPCage·8PF 6 and TPPCage·8I , respectively. 46 Technically, both catalysts are capable of activating O 2 into ROS. 47 However, the tailored charge transfer process through anion exchange in TPPCage·8I results in superior electron transfer and separation capabilities.…”

Atomic-level design of metalloenzyme-like active pockets in metal–organic frameworks for bioinspired catalysis

“…For many metalloenzymes, their extraordinary bioactivities rely on the cooperating catalysis of multiple metal moieties, which perform their duties, including electron transfer, binding and activation of substrates. 9 Herein, in this section, we emphasize the regulation of building blocks in MOFs to reproduce the homogeneous and heterogeneous multimetallic clusters of enzymes. Importantly, the synergistic effect between multiple sites will be highlighted to deepen the understanding of catalytic functions.…”

“…6,7 To this end, much effort has been devoted to developing biomimetic nanocatalysts to serve as promising alternatives to metalloenzymes. 8–11 Their superior operability and stability not only aid in overcoming the above limitations to meet the needs of practical applications but also bring in opportunities beyond natural enzymes. 12–14 It should be noted that the well-defined structure of active centers is conducive to the investigation of the catalytic mechanisms, which in turn deepens the understanding of the nature of enzymatic reactions.…”

Recent advances in porous molecular cages for photocatalytic organic conversions

“…9). 65 Cages 8-M were synthesized by a solvothermal method. Specifically, 8-Zn was synthesized via the reaction of 3,7-di( p -carboxylic)- N -( p -phenylcarboxylic)-phenothiazine and H 4 TBSC with ZnCl 2 in N , N -dimethylformamide (DMF) at 130 °C for 48 h. The synthesis of 8-Co was carried out analogously to that of 8-Zn , employing cobalt chloride instead of zinc chloride.…”