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Size is Important: Artificial Catalyst Mimics Behavior of Natural Enzymes.

ABSTRACT: Heavily substituted (R)-DTBM-SegPHOS is active in the asymmetric Pd(II)-catalyzed hydrogenation or C-O bond cleavage of ?-pivaloyloxy-1-(2-furyl)ethanone, whereas (R)-SegPHOS fails to catalyze either of these transformations. An extensive network of C-H ··· H-C interactions provided by the heavily substituted phenyl rings of (R)-DTBM-SegPHOS leads to increased stabilities of all intermediates and transition states in the corresponding catalytic cycles compared with the unsubstituted analogues. Moreover, formation of the encounter complex and its rearrangement into the reactive species proceeds in a fashion similar to that seen in natural enzymatic reactions. Computations demonstrate that this feature is the origin of enantioselection in asymmetric hydrogenation, since the stable precursor is formed only when the catalyst is approached by one prochiral plane of the substrate.

SUBMITTER: Chen J

PROVIDER: S-EPMC7076558 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Size is Important: Artificial Catalyst Mimics Behavior of Natural Enzymes.

Chen Jianzhong J Gridnev Ilya D ID

iScience 20200305 3

Heavily substituted (R)-DTBM-SegPHOS is active in the asymmetric Pd(II)-catalyzed hydrogenation or C-O bond cleavage of α-pivaloyloxy-1-(2-furyl)ethanone, whereas (R)-SegPHOS fails to catalyze either of these transformations. An extensive network of C-H ··· H-C interactions provided by the heavily substituted phenyl rings of (R)-DTBM-SegPHOS leads to increased stabilities of all intermediates and transition states in the corresponding catalytic cycles compared with the unsubstituted analogues. M ...[more]

PMID: 32193144

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Project description:If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, species richness and diversity were found to be greater on the artificial reefs than on either naturally occurring reef or sand-flat in all estuaries. Comparisons within each estuary identified significant differences in the species composition between the artificial and natural rocky-reefs. The artificial reef assemblage was dominated by sparid species including Acanthopagrus australis and Rhabdosargus sarba. The preference for a range of habitats by theses sparid species is evident by their detection on sand-flat, natural rocky reef and artificial reef habitats. The fish assemblage identified on the artificial reefs remained distinct from the adjacent rocky-reef, comprising a range of species drawn from naturally occurring rocky-reef and sand-flat. In addition, some mid-water schooling species including Trachurus novaezelandiae and Pseudocaranx georgianus were only identified on the artificial reef community; presumably as result of the reef's isolated location in open-water. We concluded that estuarine artificial reef assemblages are likely to differ significantly from adjacent rocky-reef, potentially as a result of physical factors such as reef isolation, coupled with species specific behavioural traits such as the ability of some species to traverse large sand flats in order to locate reef structure, and feeding preferences. Artificial reefs should not be viewed as direct surrogates for natural reef. The assemblages are likely to remain distinct from naturally occurring habitat comprised of species that reside on a range of adjacent natural habitats.

Dataset Information

Size is Important: Artificial Catalyst Mimics Behavior of Natural Enzymes.

Publications

Size is Important: Artificial Catalyst Mimics Behavior of Natural Enzymes.

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