Ferrocene-Containing Pseudorotaxanes in Crystals: Aromatic Interactions with Hammett Correlation

Single crystals of pseudorotaxanes, [(FcCH₂NH₂CH₂Ar)(DB24C8)][PF₆] (DB24C8 = dibenzo[24]crown-8, Fc = Fe(C₅H₄)(C₅H₅), Ar = -C₆H₃-3,4-Cl₂, -C₆H₃-3,4-F₂, -C₆H₄-4-F, -C₆H₄-4-Cl, -C₆H₄-4-Br, -C₆H₃-3-F-4-Me, -C₆H₄-4-I) and [(FcCH₂NH₂CH₂C₆H₄-4-Me)(DB24C8)][Ni(dmit)₂] (dmit = 1,3-dithiole-2,4,5-dithiolate), were obtained from solutions containing DB24C8 and ferrocenylmethyl(arylmethyl)ammonium. X-ray crystallographic analyses of the pseudorotaxanes revealed that the aryl ring of the axle moiety and the catechol ring of the macrocyclic component were at close centroid distances and parallel or tilted orientation. The structures with parallel aromatic rings showed correlation of the distances between the centroids to Hammett substituent constants of the aryl groups.

Synthesis and Characterization of 1,10-Phenanthroline-mono-N-oxides

N-oxides of N-heteroaromatic compounds find widespread applications in various fields of chemistry. Although the strictly planar aromatic structure of 1,10-phenanthroline (phen) is expected to induce unique features of the corresponding N-oxides, so far the potential of these compounds has not been explored. In fact, appropriate procedure has not been reported for synthesizing these derivatives of phen. Now, we provide a straightforward method for the synthesis of a series of mono-N-oxides of 1,10-phenanthrolines. The parent compounds were oxidized by a green oxidant, peroxomonosulfate ion in acidic aqueous solution. The products were obtained in high quality and at good to excellent yields. A systematic study reveals a clear-cut correlation between the basicity of the compounds and the electronic effects of the substituents on the aromatic ring. The UV spectra of these compounds were predicted by DFT calculations at the TD-DFT/TPSSh/def2-TZVP level of theory.

Substituent effect on the N-oxidation of 1,10-phenanthroline derivatives by peroxomonosulfate ion

Both the acidity of a series of substituted 1,10-phenanthrolines and their reactivity towardsN-oxidation are predominantly governed by electronic effects.

Formation of 1,10-Phenanthroline-N,N'-dioxide under Mild Conditions: The Kinetics and Mechanism of the Oxidation of 1,10-Phenanthroline by Peroxomonosulfate Ion (Oxone)

This paper confirms the unexpected formation of 1,10-phenanthroline-N,N'-dioxide (phenO2) when 1,10-phenanthroline (phen) is oxidized by peroxomonosulfate ion (PMS) in a neutral aqueous solution. The kinetics of oxidation of phen by PMS features a complex pH dependence. In 1.00 M H2SO4, 1,10-phenanthroline-mono-N-oxide (phenO) is the sole product of the reaction. The rate of the N-oxidation is highly dependent on pH with a maximum at pH ∼6.7. The formation of phenO occurs via two parallel pathways: the rate constant of the oxidation of phen (k = 3.1 ± 0.1 M(-1) s(-1)) is significantly larger than that of Hphen(+) [k = (4.1 ± 0.3) × 10(-3) M(-1) s(-1)] because the two N atoms are open to oxidative attack in the deprotonated substrate while an internal hydrogen bond hinders the oxidation of the protonated form. With an excess of PMS, four consecutive oxidation steps were found in nearly neutral solutions. In the early stage of the reaction, the stepwise oxidation results in the formation of phenO, which is converted into phenO2 in the second step. The formation of phenO2 was confirmed by (1)H NMR and ESI-MS methods. The results presented here offer the possibility of designing an experimental protocol for preparing phenO2.

Is UV/Ce(iv) process a chloride-resistant AOPs for organic pollutants decontamination?

Negligible AOX formation is observed in UV/Ce(iv)/Cl⁻ process due to the varied reaction pathways in the presence of chloride.

Determining the ecological impacts of organic contaminants in biosolids using a high-throughput colorimetric denitrification assay: a case study with antimicrobial agents

Land application accounts for ∼ 50% of wastewater solid disposal in the United States. Still, little is known regarding the ecological impacts of nonregulated contaminants found in biosolids. Because of the myriad of contaminants, there is a need for a rapid, high-throughput method to evaluate their ecotoxicity. Herein, we developed a novel assay that measures denitrification inhibition in a model denitrifier, Paracoccus denitrificans Pd1222. Two common (triclosan and triclocarban) and four emerging (2,4,5 trichlorophenol, 2-benzyl-4-chlorophenol, 2-chloro-4-phenylphenol, and bis(5-chloro-2-hydroxyphenyl)methane) antimicrobial agents found in biosolids were analyzed. Overall, the assay was reproducible and measured impacts on denitrification over 3 orders of magnitude exposure. The lowest observable adverse effect concentrations (LOAECs) were 1.04 μM for triclosan, 3.17 μM for triclocarban, 0.372 μM for bis-(5-chloro-2-hydroxyphenyl)methane, 4.89 μM for 2-chloro-4-phenyl phenol, 45.7 μM for 2-benzyl-4-chorophenol, and 50.6 μM for 2,4,5-trichlorophenol. Compared with gene expression and cell viability based methods, the denitrification assay was more sensitive and resulted in lower LOAECs. The increased sensitivity, low cost, and high-throughput adaptability make this method an attractive alternative for meeting the initial testing regulatory framework for the Federal Insecticide, Fungicide, and Rodenticide Act, and recommended for the Toxic Substances Control Act, in determining the ecotoxicity of biosolids-derived emerging contaminants.