The molecular representations of coal – A review

Estimation of coal aromaticities by proton-decoupled carbon-13 magnetic resonance spectra of whole coals

Trapped organic compounds and aromatic units in coals

A series of 3-hydroxyflavone (3-HF) ESIPT (excited-state intramolecular proton transfer) boronate-based fluorescent probes have been developed for the detection of peroxynitrite (ONOO–). The dyes are environmentally sensitive, and each probe exhibited a ratiometric response toward ONOO– in a micellar environment. The probes were used to image different aggregation states of amyloid-β (Aβ) in the presence of ONOO–. The 3-HF-OMe probe was found to produce a ratiometric response toward ONOO– when bound to Aβ aggregates, resulting in a novel host–guest ensemble, which adds insight into the development of other ESIPT-based probes for the simultaneous sensing of fibrous proteins/peptides and environmental ROS/RNS.

An ESIPT Probe for the Ratiometric Imaging of Peroxynitrite Facilitated by Binding to Aβ-Aggregates.

Pyridine and pyridine derivatives occur in the environment as a result of industrial and agricultural activities. The fate of pyridines in the environment is a function of both abiotic and biotic processes, including photochemical transformations, complexation, surface attenuation, transport, and biological degradation. Pyridine is readily degraded in soil, and numerous bacteria isolated from soils or sludges are capable of growing on pyridines as sole sources of carbon and/or nitrogen. Numerous substituted pyridines are also susceptible to biodegradation, although major changes in biodegrada‐bility of the pyridine ring result from slight modification of the nature orposition of ring substituents. Bacteria apparently degrade most simple pyridine derivatives, particularly hydroxypyridines and pyridinecarboxylic acids, via pathways involving hydroxylated intermediates. The initial hydroxylation step in biodegradation of many pyridines is unusual in the incorporation of oxygen derived from water. Data sugges...

Degradation of pyridines in the environment

Studies on the structure of coals. 3. Some inferences about skeletal structures

Studies on the structure of coals. 2. The valence state of carbon in coal

A study of the reactions of sodium hypochlorite with a wide variety of compounds has been carried out. The data indicate that a structure capable of producing a carbanion stable enough to undergo halogenation is oxidized by sodium hypochlorite to a ketone or a carboxylic acid. How far the oxidation will proceed is determined by enolateion resonance stabilization and by inductive and steric effects of the activating group (e.g.CO, –NO2, –CN, or –CO2H). Unactivated aromatic, hydroaromatic, alicyclic, and alkane systems are not oxidized. Heteroaromatic ring systems capable of undergoing azomethine-type addition can readily be cleaved, whereas benzenoid ring systems undergo no change. Oxidation of an activated alicyclic compound containing a tertiary sp3 carbon system may result in loss of one, two, or three carbon atoms as CO2 or CHCl3via 1,3- and 1,4-halogenation steps. Based on this investigation, a new methodology of oxidation has been developed for structural elucidation of complex materials such as coal.

Sujit K. Chakrabartty

Papers

Studies on the structure of coals. 3. Some inferences about skeletal structures

Studies on the structure of coals. 2. The valence state of carbon in coal

Sodium hypochlorite as a selective oxidant for organic compounds

Letter to the editorMolecular weights of solubilized coal products

Aromatic structures in coal