Phenylaza- and benzoazacrown compounds with a nitrogen atom conjugated with a benzene ring

Abstract

When a fast rise pulse voltage is applied to a low pressure, 2-10 mm diameter Xe discharge tube, emission covers the entire positive column region with the breakdown. Within a microsecond, however, the emission intensity starts to decrease from the cathode end of the column and the dark region spreads towards the anode. The speed of this 'de-excltation wavefronf varies from 0.5 x lo3 to 2.5 x lo3 m s-', depending on the applied voltage, and also on the capacitance which is in parallel with the cathode resistor. The propagation of the de-excitation wave i s considered to be due to the migration of excess electrons from the cathode towards the anode, followed by the reduction of impedance, and hence the electric field. of the positive column. In a 1 mm diameter tube, however, the de-excitation wave is not Observed, and the emission extinguishes simultaneously over the entire positive column 0.4 ws after the breakdown. The difference between the two extinction modes is attributed to the discharge current density. It is also shown that, in the positive column, excited species which emit vacuum ultraviolet (vuv) photons are generated mainly during the initiation stage of the breakdown period. The wv radiation efficiency can therefore be increased by narrowing the width of the pulse voltage.

Host-guest complexes of nitro-substituted N-alkylbenzoaza-18-crowns-6

“…[1][2][3]. Synthesis of aza crown compounds containing different numbers of nitrogen and oxygen atoms in the macroring attracts persistent interest [1][2][3]. From the viewpoint of potential application of aza crown compounds as structural fragments of light-sensitive ligands, specific attention is given to those possessing a nitrogen atom conjugated with a chromophore.…”

“…The ability to form such complexes underlies application of crown ethers as selective ligands toward metal cations, in particular for extraction of metal ions, in ion-selective electrodes and light-sensitive systems, etc. [1][2][3]. Synthesis of aza crown compounds containing different numbers of nitrogen and oxygen atoms in the macroring attracts persistent interest [1][2][3].…”

Nitro derivatives of N-alkylbenzoaza-15-crown-5: synthesis, structures, and complexation with metal and ammonium cations

“…Despite their simple structures, 1 aza 2,3 benzocrown ethers are poorly studied because most of their functional derivatives are scarcely accessible. 3 Earlier, 4 we have obtained formyl and nitro derivatives of N methylbenzoazacrown com pounds by stepwise transformation of the macrocycles of benzocrown ethers. This new strategy of the synthesis of functionalized azacrown ethers seems to be a promising * Dedicated to Academician I. L. Eremenko on his 60th birthday.…”

Benzoaza-15-crown-5 ethers: synthesis, structure, and complex formation with metal and ethylammonium ions

“…However, benzoaza crown ethers containing the nitrogen atom bound to the benzene ring are poorly known in spite of their relatively simple structures. 5 Earlier, we have developed 10 a procedure for the synthesis of formyl and nitro derivatives of N methyl benzoazacrown ethers 1a-f by the stepwise transforma tion of the macrocycle of benzocrown ethers 2 (for example, of 2b,c) and have shown 11-13 that these com pounds have the ability to efficiently bind calcium cations. This ability is comparable to that of benzocrown ethers and is substantially higher than the binding ability of N phenylazacrown ethers containing the macrocycle of the same size and bearing the same substituent in the benzene ring.…”