Synthesis,structure elucidation and antibacterial activity of 6-ethyl-6,9-dihydro-9-oxopyrazolo[3,4-f]quinoline-8-carboxylic acid

The preparation, structure elucidation and antibacterial activity of 6-ethyl-6,9-dihydro-9-oxopyrazolo-[3,4-f]quinoline-8-carboxylic acid are reported.     

The NMR spectra of the porphyrins. 17—Metalloporphyrins as diamagnetic shift reagents,structural and specificity studies

The nature of the metalloporphyrin-ligand complexes produced by zinc, magnesium and cobalt porphyrins with basic ligands has been investigated using the diamagnetic ring current shifts of the porphyrin on the ligand protons. The metal to nitrogen bond lengths in some metallo-meso-tetraphenylporphyrin (pyridine) complexes have been determined and compared with the data of the crystalline complexes. The geometry of the Zn meso-tetraphenylporphyrin complexes with 2-picoline, quinoline and isoquinoline has been investigated. Steric interactions between the ligand and the porphyrin in 2-picoline and quinoline produce a dramatic increase in the Zn? N bond length when compared to the unstrained analogues pyridine and isoquinoline. This large increase is associated with comparatively minor angle distortions in the complex. The specificity of the Zn meso-tetraphenylporphyrin complexation shifts has been determined for a range of benzyl and butyl compounds. The complexation shift is linearly related to the basicity of the ligand for a wide range of basicities.     

Absolute rate constants for the reactions of O(3P) atoms with DCl and DBr

Earlier work on the reactions of O(³P) atoms with HCl and HBr has been extended by measuring rate constants for A flow-tube method was used with chemiluminescent monitoring of the removal of atomic oxygen. Rate constants were measured at temperatures between 340 and 489 K for (2a) and 295 and 419 K for (2b); they can be matched by the Arrhenius expressions: where the units are cm³ molecule^?1 sec^?1 and the errors correspond to a single standard deviation. The results of a quasiclassical trajectory study of collisions of O(³P) with HCl (v = 0,1, and 2) and DCl (v= 0,1, and 2) are also reported. These strengthen the conclusion that, although the rates of reactions (1a) and (2a) are selectively enhanced by vibrationally exciting HCl or DCl, molecules with 0 < v ? 2 are mainly removed in collisions with O(³P) atoms by nonreactive relaxation.     

Partitions in squares

In this paper we study primarily partitions in different squares. A complete characterization of the least number of terms needed in different cases is given. The asymptotic number of partitions in squares and in different squares is deduced by use of numerical results obtained from extensive computer runs. Some other related problems are also discussed.     

The reaction of O(1D) with CH4

The room-temperature photolysis of N₂O (10–100 torr) at 2139 Å to produce O(¹D) has been studied in the presence of CH₄ (10–891 torr). The reactions of O(¹D) with CH₄ were found to be The method of chemical difference was used to measure the rate constant ratio k₄/(k₂ + k₃), where reactions (2) and (3) are The CH₃ radicals produced in reaction (4) react with the O₂ and NO produced in reactions (2) and (3). Thus, near the endpoint of the internal titration, ?{C₂H₆} gives an accurate measure of k₄/(k₂ + k₃). For the translationally energetic O(¹D) atoms produced in the photolysis, k₄/(k₂ + k₃) = 2.28 ± 0.20. However, if He is added to remove the excess translational energy, then k₄/(k₂ + k₃) drops to 1.35 ± 0.3.     

Influence of the linear k term on the shape of the isoenergetic surfaces in p-type GaSb,deduced from galvanomagnetic measurements

From transverse or longitudinal magnetoresistance and Hall coefficient measurements performed on three samples cut in a single crystal of p-type GaSb along selected crystallographic directions, we derive six equations involving the geometric parameters of the isoenergetic surfaces. The generally admitted valence band model for GaSb is the nonquadratic model proposed by Lax and Mavroides in the case of Germanium and Silicon. We find that this model cannot account simultaneously for all the galvanomagnetic phenomena observed on p-type GaSb, in particular for the longitudinal magnetoresistance.The existence of a linear k term in the enery expression lifts the degeneracy so that the energy maxima of the valence band are not at k (000). We show then that, at 77°K, the difference between the level of the valence band maxima and the value of the energy at k (000) may be large enough to consider the existence of a multiellipsoidal structure. This structure accounts for all the observed galvanomagentic phenomena.The ellipsoids are found along (100) and (111) directions for light and heavy holes respectively. We calculate the corresponding anisotropy coefficients: K₂=1·66 and K₁=3.