3 research outputs found
Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand
A model for cobalamin was synthesized using a new monoanionic
tetradentate
nitrogen donor ligand; 2-(4-tolyl)-1,3-bisÂ(2-isopropylpyridyl)Âpropenediimine
(Tol-BDI<sup>(2‑pp)2</sup>H) (<b>1</b>), which utilizes
isopropylpyridines as pendant arms on a β-diketiminate (BDI)
backbone. During the synthesis of <b>1</b>, the rearrangement
product, Tol-BDI<sup>(2‑pp)(4‑pp)</sup>H (<b>2</b>) was observed. Metalation of <b>1</b> with zinc iodide and
cobalt chloride yielded the corresponding Tol-BDI<sup>(2‑pp)2</sup>ZnI (<b>3</b>) and Tol-BDI<sup>(2‑pp)2</sup>CoCl (<b>4</b>) complexes. The redox properties of <b>4</b> in comparison
to cobalamin were examined through electrochemical studies. Electrochemical
and bulk reduction of complex <b>4</b> gave a diamagnetic cobaltÂ(I)
complex, Tol-BDI<sup>(2‑pp)2</sup>Co (<b>5</b>). Reactivity
of <b>5</b> toward C-X bonds was investigated using methyl iodide
and 1-iodo-2-(trimethylsilyl)Âacetylene, yielding Tol-BDI<sup>(2‑pp)2</sup>CoÂ(CH<sub>3</sub>)I and Tol-BDI<sup>(2‑pp)2</sup>CoÂ(C<sub>2</sub>SiÂ(CH<sub>3</sub>)<sub>3</sub>)I respectively. Synthesis and
characterization details for these complexes, including the crystal
structure of <b>3</b>, are reported
Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand
A model for cobalamin was synthesized using a new monoanionic
tetradentate
nitrogen donor ligand; 2-(4-tolyl)-1,3-bisÂ(2-isopropylpyridyl)Âpropenediimine
(Tol-BDI<sup>(2‑pp)2</sup>H) (<b>1</b>), which utilizes
isopropylpyridines as pendant arms on a β-diketiminate (BDI)
backbone. During the synthesis of <b>1</b>, the rearrangement
product, Tol-BDI<sup>(2‑pp)(4‑pp)</sup>H (<b>2</b>) was observed. Metalation of <b>1</b> with zinc iodide and
cobalt chloride yielded the corresponding Tol-BDI<sup>(2‑pp)2</sup>ZnI (<b>3</b>) and Tol-BDI<sup>(2‑pp)2</sup>CoCl (<b>4</b>) complexes. The redox properties of <b>4</b> in comparison
to cobalamin were examined through electrochemical studies. Electrochemical
and bulk reduction of complex <b>4</b> gave a diamagnetic cobaltÂ(I)
complex, Tol-BDI<sup>(2‑pp)2</sup>Co (<b>5</b>). Reactivity
of <b>5</b> toward C-X bonds was investigated using methyl iodide
and 1-iodo-2-(trimethylsilyl)Âacetylene, yielding Tol-BDI<sup>(2‑pp)2</sup>CoÂ(CH<sub>3</sub>)I and Tol-BDI<sup>(2‑pp)2</sup>CoÂ(C<sub>2</sub>SiÂ(CH<sub>3</sub>)<sub>3</sub>)I respectively. Synthesis and
characterization details for these complexes, including the crystal
structure of <b>3</b>, are reported
Sorption of Poly- and Perfluoroalkyl Substances (PFASs) Relevant to Aqueous Film-Forming Foam (AFFF)-Impacted Groundwater by Biochars and Activated Carbon
Despite
growing concerns about human exposure to perfluorooctanoate
(PFOA) and perfluorooctanesulfonate (PFOS), other poly- and perfluoroalkyl
substances (PFASs) derived from aqueous film-forming foams (AFFFs)
have garnered little attention. While these other PFASs may also be
present in AFFF-impacted drinking water, their removal by conventional
drinking-water treatment is poorly understood. This study compared
the removal of 30 PFASs, including 13 recently discovered PFASs, from
an AFFF-impacted drinking water using carbonaceous sorbents (i.e.,
granular activated carbon, GAC). The approach combined laboratory
batch experiments and modeling: batch sorption data were used to determine
partition coefficients (<i>K</i><sub>d</sub>) and calibrate
a transport model based on intraparticle diffusion-limited sorption
kinetics, which was used to make forward predictions of PFAS breakthrough
during GAC adsorption. While strong retention was predicted for PFOS
and PFOA, nearly all of the recently discovered polyfluorinated chemicals
and PFOS-like PFASs detected in the AFFF-impacted drinking water were
predicted to break through GAC systems before both PFOS and PFOA.
These model breakthrough results were used to evaluate a simplified
approach to predicting PFAS removal by GAC using compound-specific
retention times on a C18 column (RT<sub>C18</sub>). Overall, this
study reveals that GAC systems for the treatment of AFFF-impacted
sources of water for PFOA and PFOS likely achieve poor removal, when
operated only for the treatment of PFOS and PFOA, of many unmonitored
PFASs of unknown toxicity