MnO octahedral nanocrystals and MnO@C core-shell composites: synthesis, characterization, and electrocatalytic properties

We present a simple and facile synthesis of MnO octahedral nanocrystals and MnO@C core-shell composite nanoparticles. The synthesis is accomplished by a single-step direct pyrolysis of cetyltrimethylammonium permanganate in specially made Let-lock union cells. The products are characterized by HRSEM, HRTEM, Raman spectroscopy, and cyclic voltammetry (CV). The product consists mainly of octahedral MnO nanocrystals and MnO coated with carbon (MnO@C). The core-shell particles are observed only when the core size is smaller than 150 nm. The shape of the nanocrystals can be controlled by varying parameters such as reaction temperature and duration. As the temperature increases from 600 to 800 degrees C, the octahedral MnO crystals observed are without any carbon shell. The effect of time and temperature on the octahedral MnO nanocrystal formation is described. The electrocatalytic activities of the products are studied for oxygen reduction reaction in aqueous basic medium and are compared with bulk MnO. The MnO nanocrystals and core-shell composites exhibit higher activity than that of bulk MnO.     

Synthesis and photophysical properties of N-fused tetraphenylporphyrin derivatives: near-infrared organic dye of [18]annulenic compounds

A variety of N-fused porphyrin derivatives were prepared and their photophysical properties were investigated. Although intact N-fused tetraarylporphyrins showed almost no emission, introduction of electron-withdrawing groups such as a nitro group and a cyano group on the macrocycles caused significant refinements in their emission efficiency. Long emission wavelengths (900-1000 nm) as well as fairly large Stokes shifts (～1200 cm(-1)) are exceptionally unique photophysical properties among [18]annulenic compounds, which could be rationalized by the excited state intramolecular proton transfer (ESIPT) process. Relatively weak emission quantum yields (～5.0 × 10(-4)) and unusually short S(1) state lifetimes (～13.5 ps) are in good agreement with the ESIPT process. The solvent and substituent effects on the photophysical properties are also discussed in conjunction with the theoretical studies, where the mesityl groups at the meso-positions play a unique role.     

Inclusion of temperature dependent shell corrections in Landau theory for hot rotating nuclei

Landau theory used for studying hot rotating nuclei usually uses zero temperature Strutinsky smoothed total energy for the temperature dependent shell corrections. This is replaced in this work by the temperature dependent Strutinsky smoothed free energy. Our results show that this replacement has only marginal effect for temperatures greater than 1 MeV but plays significant role at lower temperatures.     

Thienoquinolines: X—The fragmentation of thieno(2,3-b)quinoline and its derivatives under electron impact

A study has been made of the fragmentation upon electron impact of thieno(2,3-b)quinoline and sixteen of its derivatives containing methoxy, methylenedioxy, chloro, bromo, iodo, nitro and methyl substituents. Besides these, the fragmentation patterns of some S-oxides, and S,S-dioxides were also investigated. The majority of the spectra contain molecular ions and the principal fragmentation routes involve loss of carbon monosulphide and hydrogen cyanide from the molecular ion. Rearrangement of the molecular ion appears to precede the fragmentation process in the case of S,S-dioxides. The fragmentation of 4-methylthieno(2,3-b)quinoline is closely analogous to that of alkylquinolines. The main features of these spectra can be predicted from the fragmentation pathways proposed for the parent thieno(2,3-b)quinoline.     

Piperidone derivative from Dalbergia sympathetica

An alcoholic extract of Dalbergia sympathetica, on column chromatography, yielded a compound which analyzed for C(6)H(11)NO(3) (M(+) 145). The IR spectrum of the compound showed the presence of carbonyl and hydroxyl groups. PMR, (13)C and DEPT NMR spectral studies of the compound showed the presence of one N-methyl, two methine and two methylene groups. A quaternary carbon signal at delta 172.88 ppm was assigned to C-2 carbonyl of the compound. From all the above observations and also from the HMQC 2D NMR spectrum, the compound was identified as 3, 6-dihydroxy-N-methyl-2-piperidone. This is the first report of the natural occurrence of this compound from plant sources.     

Synthesis of 3 : 4 dihydro 2H-pyrano (2, 3-b) quinolines

The synthesis of 3 : 4 dihydro 2H-pyrano(2, 3-b) quinolines is described.