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1. Sustainable wastewater reuse for agriculture

Author

Christou, Anastasis, Beretsou, Vasiliki G., Iakovides, Iakovos C., Karaolia, Popi, Michael, Costas, Benmarhnia, Tarik, Chefetz, Benny, Donner, Erica, Gawlik, Bernd Manfred, Lee, Yunho, Lim, Teik Thye, Lundy, Lian, Maffettone, Roberta, Rizzo, Luigi, Topp, Edward, and Fatta-Kassinos, Despo

Published
2024
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27. A stable radical within a N–Co–N core.

Author

Bhandari, Anirban, Park, Gyeong Min, Lee, Heui Beom, Hong, Sugyeong, Kim, Sun Hee, Byon, Hye Ryung, and Lee, Yunho

Subjects
SPECIES, IONS, DENSITY, AMINES
Abstract

A N–Co–N core is embedded within [Co(CNC)2]2+ (1) supported by two bis(4-methyl-2-(3-methyl-imidazolium)phenyl)amine (CNC) ligands. This species reveals a stable S = 1/2 state and its spin density is significantly delocalized within the N–Co–N core via parallel π-bonding interaction. Interestingly, it displays unusual stability towards O2 and water, proving that the core is well protected. Upon reduction, compound 1 was converted to its reduced diamagnetic species [Co(CNC)2]+ (2) having two amide donors and a low-spin Co(III) ion, which can be oxidized by air to regenerate 1. [ABSTRACT FROM AUTHOR]

Published
2024
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29. Metal-Ligand Cooperativity of Phosphorus-Containing Pincer Systems

Author

Kim, Seji, Kim, Yeong-Eun, Lee, Yunho, Beller, Matthias, Series Editor, Dixneuf, Pierre H., Series Editor, Dupont, Jairton, Series Editor, Fürstner, Alois, Series Editor, Glorius, Frank, Series Editor, Gooßen, Lukas J., Series Editor, Nolan, Steven P., Series Editor, Okuda, Jun, Series Editor, Oro, Luis A., Series Editor, Willis, Michael, Series Editor, Zhou, Qi-Lin, Series Editor, van Koten, Gerard, editor, Kirchner, Karl, editor, and Moret, Marc-Etienne, editor

Published
2021
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37. Tolerance to oxidative stress is required for maximal xylem colonization by the xylem‐limited bacterial phytopathogen, Xylella fastidiosa

Author

Wang, Peng, Lee, Yunho, Igo, Michele M, and Roper, M Caroline

Subjects
Microbiology, Plant Biology, Biological Sciences, Genetics, Infectious Diseases, Aetiology, 2.2 Factors relating to the physical environment, Infection, Adaptation, Physiological, Antioxidants, Bacterial Adhesion, Bacterial Proteins, Biofilms, Colony Count, Microbial, Genes, Bacterial, Host-Pathogen Interactions, Hydrogen Peroxide, Mutation, Oxidative Stress, Protein Subunits, Transcription, Genetic, Virulence, Xylella, Xylem, grapevines, oxidative stress, Pierce's disease, xylem, Crop and Pasture Production, Plant Biology & Botany, Evolutionary biology, Plant biology
Abstract

Bacterial plant pathogens often encounter reactive oxygen species (ROS) during host invasion. In foliar bacterial pathogens, multiple regulatory proteins are involved in the sensing of oxidative stress and the activation of the expression of antioxidant genes. However, it is unclear whether xylem-limited bacteria, such as Xylella fastidiosa, experience oxidative stress during the colonization of plants. Examination of the X. fastidiosa genome uncovered only one homologue of oxidative stress regulatory proteins, OxyR. Here, a knockout mutation in the X. fastidiosa oxyR gene was constructed; the resulting strain was significantly more sensitive to hydrogen peroxide (H2 O2 ) relative to the wild-type. In addition, during early stages of grapevine infection, the survival rate was 1000-fold lower for the oxyR mutant than for the wild-type. This supports the hypothesis that grapevine xylem represents an oxidative environment and that X. fastidiosa must overcome this challenge to achieve maximal xylem colonization. Finally, the oxyR mutant exhibited reduced surface attachment and cell-cell aggregation and was defective in biofilm maturation, suggesting that ROS could be a potential environmental cue stimulating biofilm development during the early stages of host colonization.

Published
2017

38. Small Molecule Activation at the acriPNP Pincer-Supported Nickel Sites

Author

Park, Sanha, Lee, Kunwoo, Padmanaban, Sudakar, and Lee, Yunho

Abstract

Nickel pincer systems have recently attracted much attention for applications in various organometallic reactions and catalysis involving small molecule activation. Their exploration is in part motivated by the presence of nickel in natural systems for efficient catalysis. Among such systems, the nickel-containing metalloenzyme carbon monoxide dehydrogenase (CODH) efficiently and reversibly converts CO2to CO at its active site. The generated CO moves through a channel from the CODH active site and is transported to a dinuclear nickel site of acetyl-coenzyme A synthase (ACS), which catalyzes organometallic C–S and C–C bond forming reactions. An analogous C–S bond activation process is also mediated by the nickel containing enzyme methyl-coenzyme M reductase (MCR). The nickel centers in these systems feature sulfur- and nitrogen-rich environments, and in the particular case of lactate racemase, an organometallic nickel pincer motif revealing a Ni–C bond is observed. These bioinorganic systems inspired the development of several nickel pincer scaffolds not only to mimic enzyme active sites and their reactivity but also to further extend low-valent organonickel chemistry. In this Account, we detail our continuing efforts in the chemistry of nickel complexes supported by acridane-based PNP pincer ligands focusing on our long-standing interest in biomimetic small molecule activation. We have employed a series of diphosphinoamide pincer ligands to prepare various nickel(II/I/0) complexes and to study the conversion of C1chemicals such as CO and CO2to value-added products. In the transformation of C1chemicals, the key C–O bond cleavage and C–E bond (E = C, N, O, or S, etc.) formation steps typically require overcoming high activation barriers. Interestingly, enzymatic systems overcome such difficulties for C1conversion and operate efficiently under ambient conditions with the use of nickel organometallic chemistry. Furthermore, we have extended our efforts to the conversion of NOxanions to NO via the sequential deoxygenation by nickel mediated carbonylation, which was applied to catalytic C–N coupling to produce industrially important organonitrogen compound oximes as a strategy for NOxconversion and utilization (NCU). Notably, the rigidified acriPNP pincer backbone that enforces a planar geometry at nickel was found to be an important factor for diversifying organometallic transformations including (a) homolysis of various σ-bonds mediated by T-shaped nickel(I) metalloradical species, (b) C–H bond activation mediated by a nickel(0) dinitrogen species, (c) selective CO2reactivity of nickel(0)–CO species, (d) C–C bond formation at low-valent nickel(I or 0)–CO sites with iodoalkanes, and (e) catalytic deoxygenation of NOxanions and subsequent C–N coupling of a nickel–NO species with alkyl halides for oxime production. Broadly, our results highlight the importance of molecular design and the rich chemistry of organonickel species for diverse small molecule transformations.

Published
2024
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39. Oxyanion-Sensitive Catalytic Activity of Ni(II)/Oxyanion Systems for Heterogeneous Organic Degradation: Differential Oxidizing Capacity of Ni(III) and Ni(IV) as High-Valent Intermediates

Author

Oh, Hoon, Kim, Ji-Young, Chae, Keun Hwa, Kim, Jaesung, Yun, Eun-Tae, Lee, Yunho, Lee, Changha, Moon, Gun-Hee, and Lee, Jaesang

Abstract

This study demonstrated that NiO and Ni(OH)2as Ni(II) catalysts exhibited significant activity for organic oxidation in the presence of various oxyanions, such as hypochlorous acid (HOCl), peroxymonosulfate (PMS), and peroxydisulfate (PDS), which markedly contrasted with Co-based counterparts exclusively activating PMS to yield sulfate radicals. The oxidizing capacity of the Ni catalyst/oxyanion varied depending on the oxyanion type. Ni catalyst/PMS (or HOCl) degraded a broad spectrum of organics, whereas PDS enabled selective phenol oxidation. This stemmed from the differential reactivity of two high-valent Ni intermediates, Ni(III) and Ni(IV). A high similarity with Ni(III)OOH in a substrate-specific reactivity indicated the role of Ni(III) as the primary oxidant of Ni-activated PDS. With the minor progress of redox reactions with radical probes and multiple spectroscopic evidence on moderate Ni(III) accumulation, the significant elimination of non-phenolic contaminants by NiOOH/PMS (or HOCl) suggested the involvement of Ni(IV) in the substrate-insensitive treatment capability of Ni catalyst/PMS (or HOCl). Since the electron-transfer oxidation of organics by high-valent Ni species involved Ni(II) regeneration, the loss of the treatment efficiency of Ni/oxyanion was marginal over multiple catalytic cycles.

Published
2024
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40. Reactivity of low-valent nickel carbonyl species supported by acridane based PNP ligands towards iodoalkanes.

Author

Park, Sanha, Seo, Mi Sook, Kim, Mingi, Lee, Kang Mun, Graham, Peter M., and Lee, Yunho

Subjects
NICKEL, COUPLING reactions (Chemistry), METHYL radicals, DENSITY functional theory, LIGANDS (Chemistry)
Abstract

Nickel monocarbonyl species with Ni(I) and Ni(0) have been synthesized and fully characterized by employing an acriPNP-Ph pincer ligand having a –C(Ph)2– bridge moiety to tether two aromatic rings. To see the effect of the bridge moiety, these complexes were structurally compared with the previously studied nickel complexes supported by PNP and acriPNP-Me ligands and methylation of the nickel carbonyl species was particularly investigated. Since a Ni(I)–CO species is known to be one of the key intermediates during the C–C coupling reaction to give an acetyl species, according to the paramagnetic mechanism of acetyl coenzyme A synthase (ACS), their reactivity toward MeI has been examined. Methylation of a nickel(I)–CO species reveals enhanced C–C coupling when both acriPNP-Me and acriPNP-Ph ligands were used. According to spin density analysis calculated by density functional theory, all Ni(I)–CO species reveal similar spin density at nickel and the carbon atom of CO. X-ray crystallographic data suggest that the corresponding selectivity may be related to the steric influence. For both (acriPNP-Ph)Ni–CO (2) and (acriPNP-Me)Ni–CO (2′), the nickel(I) site is sterically well protected, leading to selective interaction with a methyl radical to give a nickel acyl product. Steric influence was marginally observed when an anionic {(acriPNP-R)Ni–CO}− (R = Me or Ph) species reacted with MeI. The corresponding C–C coupled product was also observed from the methylation of nickel(0)–CO species. [ABSTRACT FROM AUTHOR]

Published
2024
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41. A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants

Author

Marano, Roberto B.M., Fernandes, Telma, Manaia, Célia M., Nunes, Olga, Morrison, Donald, Berendonk, Thomas U., Kreuzinger, Norbert, Tenson, Tanel, Corno, Gianluca, Fatta-Kassinos, Despo, Merlin, Christophe, Topp, Edward, Jurkevitch, Edouard, Henn, Leonie, Scott, Andrew, Heß, Stefanie, Slipko, Katarzyna, Laht, Mailis, Kisand, Veljo, Di Cesare, Andrea, Karaolia, Popi, Michael, Stella G., Petre, Alice L., Rosal, Roberto, Pruden, Amy, Riquelme, Virginia, Agüera, Ana, Esteban, Belen, Luczkiewicz, Aneta, Kalinowska, Agnieszka, Leonard, Anne, Gaze, William H., Adegoke, Anthony A., Stenstrom, Thor A., Pollice, Alfieri, Salerno, Carlo, Schwermer, Carsten U., Krzeminski, Pawel, Guilloteau, Hélène, Donner, Erica, Drigo, Barbara, Libralato, Giovanni, Guida, Marco, Bürgmann, Helmut, Beck, Karin, Garelick, Hemda, Tacão, Marta, Henriques, Isabel, Martínez-Alcalá, Isabel, Guillén-Navarro, Jose M., Popowska, Magdalena, Piotrowska, Marta, Quintela-Baluja, Marcos, Bunce, Joshua T., Polo-López, Maria I., Nahim–Granados, Samira, Pons, Marie-Noëlle, Milakovic, Milena, Udikovic-Kolic, Nikolina, Ory, Jérôme, Ousmane, Traore, Caballero, Pilar, Oliver, Antoni, Rodriguez-Mozaz, Sara, Balcazar, Jose L., Jäger, Thomas, Schwartz, Thomas, Yang, Ying, Zou, Shichun, Lee, Yunho, Yoon, Younggun, Herzog, Bastian, Mayrhofer, Heidrun, Prakash, Om, Nimonkar, Yogesh, Heath, Ester, Baraniak, Anna, Abreu-Silva, Joana, Choudhury, Manika, Munoz, Leonardo P., Krizanovic, Stela, Brunetti, Gianluca, Maile-Moskowitz, Ayella, Brown, Connor, and Cytryn, Eddie

Published
2020
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