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Here we have developed a novel molecular design that enables six-electron redox activity in fused phenazine-based organic scaffolds. Combined electrochemical and spectroscopic tests successfully confirm the two-step 6e - redox mechanism. This work offers an opportunity for achieving energy-dense redox flow batteries, on condition that the solubility and stability issues are addressed.
Concentrated hydrogen-bonded electrolytes (CoHBEs) are structured, electrochemically stable, less-volatile alternatives to aqueous and dilute nonaqueous electrolytes, however, with high viscosities that limit molecular diffusion. This work provides an understanding of the proton conduction mechanism in CoHBEs based on mixtures of acids and azoles and establishes a link between the structurally dictated transport properties and the proton-coupled electron transfer (PCET) reaction rates that can be leveraged for enhancing electrochemical reactions. Diffusion and relaxation NMR studies suggest a breaking of the viscosity–conductivity tradeoff, where at high azole concentrations (>45 mol%), Grotthuss transport is more likely with lowered proton transfer energy barriers between the azole and the acid according to the machine learning (ML) accelerated ab initio path integral MD (AI-PIMD) simulations. Proton conduction pathways are found to be switchable between the hydrogen bonding networks of the acid and the azole, with imidazole chain forming structures better facilitating Grotthuss hopping. Supported by small-angle neutron scattering studies, the chains are found to have six member molecules on average with maximum of 3 to 4 imidazole/imidazoliums at 50 to 60 mol%. Despite their high viscosities, the measured PCET rates for quinones and phenazines measured in the protic CoHBEs present relatively high electron transfer rate constants (k 0 ~ 10 −4 cm/s), validated by rotating disc electrode and scanning electrochemical microscopy measurements. The results demonstrate that strategic tuning of hydrogen-bond donor–acceptor interactions enables the decoupling of proton transport and viscosity, thereby impacting PCET reactions.
We grew a soil enrichment culture to identify organisms that anaerobically oxidize phenazine-1-carboxylic acid. A strain of Citrobacter portucalensis was isolated from this enrichment and sequenced by both Illumina and PacBio technologies. It has a genome with a length of 5.3 Mb, a G+C content of 51.8%, and at least one plasmid.
The ability to effectively store energy produced by intermittent renewable sources is a critical challenge for chemists and materials scientists. Redox flow batteries (RFB), which generate current by the flow of electrons between dissolved redox active compounds in separate solutions, are envisioned as a method to store renewable energy at the electrical grid scale. The best known examples of RFBs are driven by redox active metal or main group complexes. Within the past decade, redox active organic molecules have begun to be used in the construction of RFBs with high cell potential and cycle stability, at economical price points. Of particular interest are substituted dihydroxy phenazines, a class of heterocycles, that have recently been used as an anolyte for aqueous organic RFBs. Recent work indicates that different regioisomers of dihydroxyphenazine show dramatically different solubility and stability under electrochemical cycling conditions. Of particular interest was 1,3-dihydroxyphenazine (1,3-DHP), which showed greater than 1.5 M solubility in 2M KOH and excellent electrochemical stability. Current methods of producing 1,3-DHP, however, are low yielding and cumbersome. In the article proposal that follows, we offer an improved method of producing 1,3-DHP at high purity and moderate yield. The method detailed below was used by the Materials Engineering Research Facility (MERF) at Argonne National Lab to deliver more than 1.5 kg of this compound for use in the construction of aqueous organic RFBs.
The present invention provides for a system comprising (a) a first nucleic acid comprising a nucleotide sequence encoding a nucleotide sequence of interest operatively linked to a promoter comprising a repressor polypeptide binding site, and (b) a second nucleic acid comprising a nucleotide sequence encoding a repressor polypeptide having at least 70% amino acid identity with EilR, SmvR, KmrR, RcdA, or QacR; wherein expression of the nucleotide sequence of interest from the promoter is induced by the presence of a hydrophobic inducer, such as a hydrophobic cation inducer, such as a triarylmethane, acridine, phenazine, phenothiazine, or xanthene.
The present invention provides for a system comprising (a) a first nucleic acid comprising a nucleotide sequence encoding a nucleotide sequence of interest operatively linked to a promoter comprising a repressor polypeptide binding site, and (b) a second nucleic acid comprising a nucleotide sequence encoding a repressor polypeptide having at least 70% amino acid identity with EilR, SmvR, KmrR, RcdA, or QacR; wherein expression of the nucleotide sequence of interest from the promoter is induced by the presence of a hydrophobic inducer, such as a hydrophobic cation inducer, such as a triarylmethane, acridine, phenazine, phenothiazine, or xanthene.
Bacteria are recognized for their diverse metabolic capabilities, yet the impact of microbe-microbe interactions on multispecies community structure and dynamics is poorly understood. Cell-to-cell signaling in the form of quorum sensing (QS) often regulates secondary metabolite production and microbial interactions. Here, we examine how acylhomoserine lactone (AHL)-mediated QS impacts microbial community structure in a 10-member synthetic community of isolates from Populus deltoides . To explore the role of QS in microbial community structure and dynamics, we disrupted AHL signaling by exogenous addition of AiiA-lactonase, an enzyme that cleaves the lactone ring. Microbial community structure resulting from signal inactivation, as measured by 16S rRNA amplicon sequencing and secondary metabolite production, was assessed after successive passaging of the community. Further, we investigated the impact of quorum quenching on specific microbe-microbe interactions using pairwise inhibition assays. Our results indicate that AHL inactivation alters the relative abundance of dominant community members at later passages but does not impact the overall membership in the community. Quorum quenching significantly alters the metabolic profile in lactonase-treated communities. This metabolic alteration impacts microbe-microbe interactions through decreased inhibition of other community members. Together, these results indicate that QS impacts microbial community structure through the regulation of secondary metabolites in dominant members and that the membership of microbial communities can be relatively stable despite changes in metabolic profiles.