Mechanism of O2-accelerated sonolysis of bisphenol A

The effects of dissolved gases on the sonochemical degradation of bisphenol A (BPA) were studied at a frequency of 500 kHz. BPA degradation rate increased in the order O(2)>Ar>air>N(2). The rate constant for oxygen (2.6 h(-1)) was approximately two fold higher than that for argon (1.2 h(-1)). A primary intermediate (2,3-dihydro-2-methylbenzofuran), a typical intermediate of BPA formed during attack by OH radicals, was detected only in the presence of oxygen, revealing that a different reaction path was responsible for the enhancement of decomposition.     

Enzyme‐Free Quinone Crosslinking Reaction for Proteins: A Macromolecular Characterization Study Using Gelatin

To mimic the quinone hardening of extracellular proteins in invertebrates, we investigated an enzyme‐free crosslinking of gelatin by HQ in a neutral aqueous phase. The mixture was rapidly transformed to a yellowish brown, thermally and mechanically stable hydrogel in the presence of a simple copper(II) salt. A dehydrated thin film made of the mixture was flexible, tough, and showed a large ultimate breaking force. Physicochemical examination of the gel suggested that the basic amino acid residues (lysine, hydroxylysine, and histidine) of the protein were modified by the quinone ring to form 2–6 crosslinks per protein. The enzyme‐free crosslinking reaction is discussed with consideration of a copper(II) ion‐catalyzed oxidation of HQ and the hydroquinone/protein adducts.

     

Coupling of an N‐Heterocyclic Carbene on Iron with Alkynes to Form η5‐Cyclopentadienyl‐Diimine Ligands

A cyclometalated N‐heterocyclic carbene ligand in a half‐sandwich iron complex was found to couple with alkynes, leading to a unique type of ring opening of the carbene ligand and the formation of ferrocenyl–diimine complexes. An intermediary iron complex obtained from the reaction with phenylacetylene reveals that the ring opening follows the formation of a fused heterocycle consisting of an imidazole ring and two alkynes.     

Turn‐On Fluorogenic and Chromogenic Detection of Small Aromatic Hydrocarbon Vapors by a Porous Supramolecular Host

Benzene, toluene, ethylbenzene, the isomers of xylene, and trimethylbenzene are harmful volatile organic compounds and pose risks to human health and the environment. However, there are currently no effective chemosensors for vapors of these compounds. A porous supramolecular host for turn‐on fluorogenic and chromogenic detection of the vapors of small aromatic hydrocarbons is presented. The host was constructed from a naphthalenediimide derivative that was supramolecularly connected to tris(pentafluorophenyl)borane. The amorphous powder form of the host allowed for effective accommodation of vapors of small aromatic hydrocarbons, resulting in a guest‐dependent fluorescence emission. Increases in the fluorescence yield of 76‐, 46‐, and 37‐fold were observed with toluene, benzene, and m‐xylene, respectively. Negligible responses were obtained with common organic solvents. This simple supramolecular host could be applied as a useful sensor of small aromatic hydrocarbon vapors.     

Revisiting Phosphorus Analogues of Phthalimides and Naphthalimides: Syntheses and Comparative Studies

A series of phosphorus analogues of aromatic‐fused monoimides (phthalimides and naphthalimides) bearing a mesityl group on the P center have been synthesized. In a comparison of their photophysical, electrochemical, and thermal properties with those of the corresponding imides, the impact of P incorporation was revealed. Furthermore, theoretical studies using DFT methods were conducted to understand their properties.     

Assignment of finely resolved 13C NMR spectra of poly(vinyl acetate)

¹³C NMR spectra of two poly(vinyl acetate)s (PVAC) with different tacticities (r‐diad, 0.54 and 0.57) were measured, and their peak intensities were compared with the calculated ones. The methine carbon signals were assigned with pentads in the order of mmmm, mmmr + rmmr, rmrr + mmrr, rrrr, mmrm, rmrm, mrrr, mrrm from low field. The methylene carbon signals were assigned with tetrads (partly with hexads) as rmr, rrr(mrrrm, mrrrr, rrrrr), mmr + mrr, mrm and mmm from low field. Some assignments are different from those previously reported. The methyl carbon signals showed splittings which were partly assigned.