Synthesis, chemical properties and mutagenicity of 1,6- and 3,6-dinitrobenzo[a]pyrenes

Nitration of benzo[a]pyrene (BaP) with HNO3 (d = 1.38) produced a mixture of dinitroBaPs (1,6- and 3,6-isomers) and mononitroBaPs (1-, 3- and 6-isomers). Pure 1,6-dinitroBaP and 3,6-dinitroBaP were obtained by the reduction of the dinitroBaPs mixture with NaSH to yield the separable products 1-amino-6-nitroBaP and 3-amino-6-nitroBaP, followed by conversion to dinitroBaPs via the the diazonium salts. The half-wave potentials (E1/2) corresponding to the one-electron reduction of dinitroBaPs were measured and the relationship of these values to the mutagenicity is discussed.     

On the mixed complexes of tetracycline metal chelates

The mixed complexes of chlorotetracycline-metal chelates with isomazid, penicillin G, and dihydrostreptomycin were examined with Th⁺⁴, Cu⁺², Fe⁺³, Co⁺³, and Ni⁺² ions.A mechanism is proposed that accounts for the formation of the mixed complexes, cationic chelates of tetracycline have a molar ratio of 1 : 1 of metal to chlorotetracycline and mixed complexes are formed by combining with other ligands through the remaining covalencies. The properties and preparation of the mixed complexes are given     

Raman scattering in hydrogenated amorphous silicon under high pressure

The first studies on the pressure dependences of the first-order Raman spectra in plasma-deposited a-Si:H films are reported. With increasing pressure up to 25 kbar the TO optical phonon band shows a shift in peak to higher frequencies with a sharpening of width while the TA acoustic phonon band shows a shift in peak to lower frequencies with a broadening of width. The LO optical phonon band shows a shift in peak to higher frequencies whereas the LA acoustic phonon band remains unchanged. These pressure effects are discussed with changes in force constant and structural disorder. The alloying effect of H atoms on the Raman spectra is also discussed while comparing the pressure effects.     

Helicity Induction and Its Static Memory of Poly(biphenylylacetylene)s Bearing Pyridine N‐Oxide Groups and Their Use as Asymmetric Organocatalysts

Novel poly(biphenylylacetylene) derivatives carrying different types of pyridine N‐oxide units with a bulky or less‐bulky substituent at a different position as the functional pendant groups (poly‐ 2a and poly‐ 2b ) were synthesized by the rhodium‐catalyzed polymerization of the corresponding monomers. The influence of the steric environment around the catalytically active pyridine N‐oxide sites on the helicity induction and its static memory as well as the asymmetric catalytic activities of the resulting helical polymers with a macromolecular helicity memory was investigated. The polyacetylenes formed an excess one‐handed helical conformation upon noncovalent interactions with optically active alcohols and the induced macromolecular helicities of the polyacetylenes were efficiently memorized after the removal of the chiral inducers. Poly‐ 2b with the macromolecular helicity memory showed an enantioselectivity for the catalytic asymmetric allylation of benzaldehydes, producing optically active allyl alcohols, although their enantioselectivities were low. On the other hand, poly‐ 2a exhibited a negligible catalytic activity probably due to the bulky substituent at the o‐position of the pyridine N‐oxide residues, while poly‐ 2a underwent a unique helix‐inversion with the increasing concentration of chiral alcohols and the opposite helicity of poly‐ 2a was further successfully memorized. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2481–2490