A molecular orbital treatment of the electronic spectra of some tryptamines

The electronic absorption spectra of tryptamine, 5-methoxytryptamine, 6-fluorotryptamine, N-acetyl-5-hydroxytryptamine, gramine, and melatonin were investigated. The observed transitions were π–π*, and the values of band maxima and intensity reflected an extent of interaction between the indole ring and the alkylamine side chain. Molecular orbital calculations at the level of INDO /S –CI were performed on all the studied molecules. State functions and transition energies were calculated. The correspondence between the experimental and theoretical results was satisfactory. © 1992 John Wiley & Sons, Inc.     

Convenient synthesis of arylazo derivatives of quinoxaline, 1,4-benzothiazine,and 1,4-benzoxazine

Arylazo derivatives of quinoxaline (1,4-benzodiazine), 1,4-benzothiazine, and 1,4-benzoxazine have been prepared by condensation of hydrazidoyl halides with o-phenylenediamine, o-aminothiophenol, and o-aminophenol, respectively (Table I). This method seems to be more general than the approach using coupling of reactive diazonium salts with, e.g., 277–1,4-benzothiazine. Both the spectral data and the results of HMO calculations of bonding energies of the azo compounds obtained in this study indicate that they exist predominantly in the hydrazone tautomeric form.     

On the numerical solution of integral equations of the second kind with weakly singular kernels

The purpose of this paper is to introduce the (Toeplitz) quadrature method for solving Fredholm integral equations of the second kind with mildly singular kernels. We are presented some numerical examples for the computation of the error estimate using the MathCad package.     

Extension of semiclean rings

Czechoslovak Mathematical Journal - This paper aims at the study of the notions of periodic, UU and semiclean properties in various context of commutative rings such as trivial ring extensions,...     

The extended homogeneous balance method and its applications for a class of nonlinear evolution equations

The extended homogeneous balance method with the aid of computer algebraic system Maple, is proposed for seeking the travelling wave solutions for a class of nonlinear evolution equations, in which the homogeneous balance method is applied to solve the Riccati equation and the reduced nonlinear evolution equations, respectively. Many new exact travelling wave solutions are successfully obtained. The method is straightforward and concise, and it can be also applied to other nonlinear evolution equations.     

Multilayer polarizing grating mirror used for the generation of radial polarization in Yb:YAG thin-disk lasers

The design, fabrication and characterization of a multilayer polarizing grating mirror developed for an Yb:YAG thin-disk laser resonator are reported. The potential of the proposed solution is discussed together with the first demonstration of a radially polarized Yb:YAG thin-disk laser.     

Synthesis,spectroscopic investigation and biological activity of metal complexes with ONO trifunctionalalized hydrazone ligand

Mn^II, Fe^III, Co^II, Ni^II, Cu^II, Zn^II, La^III, Ru^III, Hf^IV, Zr^IV and U^VI complexes of 4-methylphenylamino acetoacetylacetone hydrazone have been synthesized and characterized by elementals analyses, i.r., u.v.–vis. spectra, magnetic moments, conductances, thermal analyses (d.t.a and t.g.a) and e.s.r measurements. The i.r. data show that, the ligand behaves as a neutral bidentate type (10), (13) and neutral tridentate type (4), (11), (12) and (21) monobasic bidentate type (7) or monobasic tridentate type (2), (3), (5), (6), (8), (14), (15), (16), (18), (19), (20) and (22) or dibasic tridentate type (5), (9) and (17) towards the metal ion. Molar conductances in DMF solution indicate that, the complexes are non-electrolytes. The e.s.r spectra of solid complexes (8) and (10) show axial type spectra with , d(x²-y²) ground state with significant covalent bond character. However, complex (12), shows an isotropic type, indicating a octahedral manganese(II) complex. Antibacterial and antifungal tests of the ligand and some of its metal complexes are also carried out and it has been observed that, the complexes are more potent bactericides and fungicides than the ligand.     

Multicomponent reactions in a one-pot synthesis of α-aminophosphonates and α-aminophosphonic diamides with anti-inflammatory properties

Abstract  

Schiff-base Kabachnik–Fields intermediates generated in situ from substituted pyrazole-4-carbaldehyde and 2-aminothiophene derivatives were trapped by dialkyl phosphites to produce the corresponding α-aminophosphonates in moderate yields. The latter products could be also obtained in excellent yields (≥75%) by directly applying the phosphorus reagents to the Schiff bases. Next, dialkyl phosphites were applied to one of the parent aldehydes to give the expected α-hydroxyphosphonate derivatives. Applying hexaalkyl triamidophosphites to the Schiff base in ethanol afforded methylphosphonic diamide derivatives, whereas ring attack on the pyrazole ring occurred when the same amidophosphites were applied to the parent aldehyde to give the corresponding alkylidenephosphorane ylides in an open structure form in good yields. Some of the new compounds exhibited considerable anti-inflammatory properties.