Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan.
Published: August 2002
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Article Abstract
m-Phenylene-coupled carbenonitrenes [(3-nitrenophenyl)methylene (2-H), (3-nitrenophenyl)fluoromethylene (2-F), (3-nitrenophenyl)chloromethylene (2-Cl), (3-nitrenophenyl)bromomethylene (2-Br)] have been investigated computationally (with B3LYP, MCSCF, CASPT2, ROMP2, and QCISD(T) methods) and experimentally (with IR, UV, and ESR spectroscopy). For each species, five electronic states were considered. At the highest level of theory explored, the parent compound (2-H) has a quintet ground state, but its halogen derivatives (2-X, X = F, Cl, and Br) have triplet ground states. A linear relationship between the Q[bond]T energy gap of 2-X and the T-S gap of the corresponding phenylcarbenes 8-X is found, which can be helpful in rationalizing and predicting ground-state multiplicities in m-phenylene-linked carbenonitrenes and similar species. Precursors for the photochemical generation of 2-X (X = H, F, Cl, and Br) were synthesized and photolyzed in matrixes (Ar, triacetin) at low temperatures. IR (Ar, 13 K) and ESR (triacetin, 77 K) data are compatible with the generation of triplet halocarbenonitrenes 2-X, (X = F, Cl, and Br). All four compounds upon further irradiation undergo isomerization to substituted cyclopropenes 5-X (X = H, F, Cl, and Br), as suggested by their IR spectra.
The rising popularity of bioconjugate therapeutics has led to growing interest in late-stage functionalization (LSF) of peptide scaffolds. α,β-Unsaturated amino acids like dehydroalanine (Dha) derivatives have emerged as particularly useful structures, as the electron-deficient olefin moiety can engage in late-stage functionalization reactions, like a Giese-type reaction. Cheap and widely available building blocks like organohalides can be converted into alkyl radicals by means of photoinduced silane-mediated halogen-atom transfer (XAT) to offer a mild and straightforward methodology of alkylation.
Molecular frameworks have recently shown a great potential in atmospheric water harvesting, in which the water release at low temperatures is challenging. Anion-organic frameworks based on anion-coordination chemistry are presented herein to meet this challenge. These frameworks are prepared as tubular single crystals in pure water from the in-situ protonation and crystallization of pyridine-terminated triphenylamine derivatives with hydrochloric or hydrobromic acid.
Excessive inflammatory responses to viral infections, known as cytokine storms, are caused by overactivation of endolysosomal Toll-like receptors (TLRs) (TLR3, TLR7, TLR8, and TLR9) and can be lethal, but no specific treatment is available. Some quinoline derivatives with antiviral activity were tried during the recent coronavirus disease 2019 (COVID-19) pandemic, but showed serious toxicity, and their efficacy for treating viral cytokine storms was not established. Here, in order to discover a low-toxicity quinoline derivative as a candidate for controlling virally induced inflammation, we synthesized a series of derivatives of amodiaquine (ADQ), a quinoline approved as an antimalarial, and tested their effects on TLRs-mediated production of inflammatory cytokines and cell viability in vitro.
Seasonal algal blooms in surface waters can adversely impact drinking water quality. Oxidative treatment has been demonstrated as an effective measure for the removal of algal cells. However, this, in turn, leads to the release of algal organic matter (AOM).
Wet chemical oxidation (WCO) methods measure total organic carbon (TOC) in aqueous solutions through the formation and detection of carbon dioxide (CO). Prior research documents chloride (Cl) interference during WCO. However, the mechanism that determines WCO interference is not established.
