Catalytic Ni(II) in Reactions of SmI<sub>2</sub>: Sm(II)- or Ni(0)-Based Chemistry?

Choquette, Kimberly A.; Sadasivam, Dhandapani V.; Flowers, Robert A.

doi:10.1021/ja204287n

Cited by 39 publications

(20 citation statements)

References 33 publications

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“…Nickel nanoparticles (NiNPs) were purchased from Sun Innovations (Fremont, CA) and have been previously characterized [15,56]. They are characterized as spherical in shape with a ~20 nm diameter, having a specific surface area of 40–60 m 2 /g, a metal purity of 99.9%, and insoluble in water.…”

Section: Methodsmentioning

confidence: 99%

“…Size and shape have previously been verified by measuring digitized TEM images with Adobe Photoshop and determining pixel length of >100 NiNPs [15]. Furthermore, the oxidation state of these NiNPs is oxidation state (0) zero [56]. Prior to exposure, NiNPs were suspended in a sterile, 0.1% pluronic F-68 (Sigma) in phosphate buffered saline solution and dispersed for two hours using a bath sonicator at room temperature.…”

Section: Methodsmentioning

confidence: 99%

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Nickel Nanoparticles cause exaggerated lung and airway remodeling in mice lacking the T-box transcription factor, TBX21 (T-bet)

et al. 2014

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BackgroundNickel nanoparticles (NiNPs) are increasingly used in a variety of industrial applications, including the manufacturing of multi-walled carbon nanotubes (MWCNTs). While occupational nickel exposure is a known cause of pulmonary alveolitis, fibrosis, and cancer, the health risks of NiNPs are not well understood, especially in susceptible individuals such as asthmatics. The T-box transcription factor Tbx21 (T-bet) maintains Th1 cell development and loss of T-bet is associated with a shift towards Th2 type allergic airway inflammation that characterizes asthma. The purpose of this study was to determine the role of T-bet in susceptibility to lung remodeling by NiNPs or MWCNTs.MethodsWild-type (WT) and T-bet-/- mice were exposed to NiNPs or MWCNTs (4 mg/kg) by oropharyngeal aspiration (OPA). Necropsy was performed at 1 and 21 days. Bronchoalveolar lavage fluid (BALF) was collected for differential counting of inflammatory cells and for measurement of cytokines by ELISA. The left lung was collected for histopathology. The right lung was analyzed for cytokine or mucin (MUC5AC and MUC5B) mRNAs.ResultsMorphometry of alcian-blue/periodic acid Schiff (AB/PAS)-stained lung tissue showed that NiNPs significantly increased mucous cell metaplasia in T-bet-/- mice at 21 days (p < 0.001) compared to WT mice, and increased MUC5AC and MUC5B mRNAs (p < 0.05). MWCNTs also increased mucous cell metaplasia in T-bet-/- mice, but to a lesser extent than NiNPs. Chronic alveolitis was also increased by NiNPs, but not MWCNTs, in T-bet-/- mice compared to WT mice at 21 days (P < 0.001). NiNPs also increased IL-13 and eosinophils (p < 0.001) in BALF from T-bet-/- mice after 1 day. Interestingly, the chemokine CCL2 in the BALF of T-bet-/- mice was increased at 1 and 21 days (p < 0.001 and p < 0.05, respectively) by NiNPs, and to a lesser extent by MWCNTs at 1 day. Treatment of T-bet-/- mice with a monoclonal anti-CCL2 antibody enhanced NiNP-induced mucous cell metaplasia and MUC5AC mRNA levels (p < 0.05), yet marginally reduced NiNP-induced alveolitis.ConclusionThese findings identify T-bet as a potentially important susceptibility factor for NiNP exposure and to a lesser extent for MWCNT exposure, and suggests that individuals with asthma are at greater risk.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Nickel Nanoparticles cause exaggerated lung and airway remodeling in mice lacking the T-box transcription factor, TBX21 (T-bet)

et al. 2014

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“…[4] Transition-metal salts, most commonly Ni II are used in place of HMPAi ns ome reactions including Barbier-type cross-coupling reactions, but it has been demonstrated that SmI 2 reducesN i II to Ni 0 which acts as the active coupling reagent. [5] The most widely used proton donors are water,m ethanol, and glycols and it is recognized that more hindered alcoholsd on ot form strong ground state complexes with Sm II . [6] Proton donors and Lewis bases that coordinate to SmI 2 may affect reactions through severald ifferentp athways.…”

Section: Introductionmentioning

confidence: 99%

Contrasting Effect of Additives on Photoinduced Reactions of SmI₂

Nimkar

Maity

Flowers

et al. 2019

Chemistry A European J

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The work described herein compares the effect of additives (HMPA, methanol, ethylene glycol, pinacol, N-methylethanolamine) on thermal and photochemical reactions of samarium diiodide (SmI 2 ). In thermalr eactions,a dditives that coordinate to SmI 2 induce as ignificant increase in reaction rate. In photochemicalr eactions,t he presence of an electronegative atom with ah ighly localizednegative charge on the substrate leads to ar ate deceleration. In order to benefit from the columbic interaction with the positivelyc harged samarium cation, these substrates react preferentially by an inner sphere reduction mechanism. The addition of ligands preventst his close interactionc ausingr ate retardation. Furthermore, studies demonstrate that excited state quenching of Sm II by ethylene glycol and other additivesi ndicate that it is unlikely to be the major cause for the observed rate retardation.T his effect provides as imple diagnostic tool to distinguish between an inner and an outer sphere reduction mechanism. Results and DiscussionTo study this system,a nthracene, trans-stilbene, benzyl chloride, halobenzenes, cyclohexanone and 3-methyl-2-butanone were chosen as substrates since they are representative of the [a] Dr.

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“…Infra-Red (FT-IR) spectroscopy (Blackmond, 2005), ultraviolet-visible (UV/VIS) spectroscopy (Choquette et al, 2011), or nuclear magnetic resonance (NMR) spectroscopy (Mathew et al, 2006) to directly determine the concentration of the reaction components over the course of the reaction. These techniques are expensive and require a level of training which by far surpasses the level of first year undergraduate students.…”

Section: Introductionmentioning

confidence: 99%