skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Selective Electroenzymatic Oxyfunctionalization by Alkane Monooxygenase in a Biofuel Cell
Abstract Aliphatic synthetic intermediates with high added value are generally produced from alkane sources (e.g., petroleum) by inert carbon–hydrogen (C−H) bond activation using classical chemical methods (i.e. high temperature, rare metals). As an alternative approach for these reactions, alkane monooxygenase fromPseudomonas putida(alkB) is able to catalyze the difficult terminal oxyfunctionalization of alkanes selectively and under mild conditions. Herein, we report an electrosynthetic system using an alkB biocathode which produces alcohols, epoxides, and sulfoxides through bioelectrochemical hydroxylation, epoxidation, sulfoxidation, and demethylation. The capacity of the alkB binding pocket to protect internal functional groups is also demonstrated. By coupling our alkB biocathode with a hydrogenase bioanode and using H2as a clean fuel source, we have developed and characterized a series of enzymatic fuel cells capable of oxyfunctionalization while simultaneously producing electricity.  more » « less
Award ID(s):
1740656
PAR ID:
10143230
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Angewandte Chemie International Edition
Volume:
59
Issue:
23
ISSN:
1433-7851
Page Range / eLocation ID:
p. 8969-8973
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Ammonia can be employed as an important co-reactant for efficient light alkane conversion. The reaction is achieved through either ammonia reforming (for COx-free H2and HCN) or ammonia dehydrogenation (for acetonitrile and H2). 
    more » « less
  2. Abstract A traditional composite cathode for proton‐conducting solid oxide fuel cells (H‐SOFCs) is typically obtained by mixing cathode materials and proton conducting electrolyte of BaCe0.7Y0.2Zr0.1O3–δ(BZCY), providing chemical and thermal compatibility with the electrolyte. Here, a series of triple‐conducing and cobalt‐free iron‐based perovskites as cathodes for H‐SOFCs is reported. Specifically, BaCexFe1–xO3–δ(x = 0.36, 0.43, and 0.50) shows various contents of two single phase perovskites with an in situ heterojunction structure as well as triple conductivity by tailoring the Ce/Fe ratios. The cell performance with the optimized BaCe0.36Fe0.64O3–δ(BCF36) cathode composition reaches 1056 mW cm−2at 700 °C. Moreover, a record cell performance of 1525 mW cm−2at 700 °C is obtained by modifying the BCF36 cathode microstructure through a spraying method, demonstrating high promise with Co‐free cathodes for H‐SOFCs. 
    more » « less
  3. Abstract The production of olefins via on‐purpose dehydrogenation of alkanes allows for a more efficient, selective and lower cost alternative to processes such as steam cracking. Silica‐supported pincer‐iridium complexes of the form [(≡SiO−R4POCOP)Ir(CO)] (R4POCOP=κ3‐C6H3‐2,6‐(OPR2)2) are effective for acceptorless alkane dehydrogenation, and have been shown stable up to 300 °C. However, while solution‐phase analogues of such species have demonstrated high regioselectivity for terminal olefin production under transfer dehydrogenation conditions at or below 240 °C, in open systems at 300 °C, regioselectivity under acceptorless dehydrogenation conditions is consistently low. In this work, complexes [(≡SiO−tBu4POCOP)Ir(CO)] (1) and [(≡SiO−iPr4PCP)Ir(CO)] (2) were synthesized via immobilization of molecular precursors. These complexes were used for gas‐phase butane transfer dehydrogenation using increasingly sterically demanding olefins, resulting in observed selectivities of up to 77 %. The results indicate that the active site is conserved upon immobilization. 
    more » « less
  4. The hydroxylation of C–H bonds can be carried out by the high-valent CoIII,IV2(µ-O)2complex2asupported by the tetradentate tris(2-pyridylmethyl)amine ligand via a CoIII2(µ-O)(µ-OH) intermediate (3a). Complex3acan be independently generated either by H-atom transfer (HAT) in the reaction of2awith phenols as the H-atom donor or protonation of its conjugate base, the CoIII2(µ-O)2complex1a. Resonance Raman spectra of these three complexes reveal oxygen-isotope-sensitive vibrations at 560 to 590 cm−1associated with the symmetric Co–O–Co stretching mode of the Co2O2diamond core. Together with a Co•••Co distance of 2.78(2) Å previously identified for1aand2aby Extended X-ray Absorption Fine Structure (EXAFS) analysis, these results provide solid evidence for their “diamond core” structural assignments. The independent generation of3aallows us to investigate HAT reactions of2awith phenols in detail, measure the redox potential and pKaof the system, and calculate the O–H bond strength (DO–H) of3ato shed light on the C–H bond activation reactivity of2a. Complex3ais found to be able to transfer its hydroxyl ligand onto the trityl radical to form the hydroxylated product, representing a direct experimental observation of such a reaction by a dinuclear cobalt complex. Surprisingly, reactivity comparisons reveal2ato be 106-fold more reactive in oxidizing hydrocarbon C–H bonds than corresponding FeIII,IV2(µ-O)2and MnIII,IV2(µ-O)2analogs, an unexpected outcome that raises the prospects for using CoIII,IV2(µ-O)2species to oxidize alkane C–H bonds. 
    more » « less
  5. Abstract Molecular hydrogen (H2) is an abundant and reactive constituent of Earth's atmosphere, with links to climate and air quality. Anthropogenic emissions of H2are expected to rise as the use of H2as an energy source increases. Documenting past variations in atmospheric H2will help to validate current understanding of the global H2budget. The modern instrumental record begins in the 1980s; there is little information about atmospheric H2prior to that time. Here, we use firn air measurements from a 2001 South Pole campaign to reconstruct atmospheric H2levels over the 20th century. Inversion of the measurements indicates that H2over South Pole has increased from 350–540 ppb from 1910–2000. A biogeochemical box model indicates that the atmospheric burden of H2increased by 37% over that time. The rise in H2is consistent with increasing H2emissions from fossil fuel combustion and increasing atmospheric production from methane oxidation. 
    more » « less