complexation reactions between methylthymol blue and fe , a l ,ga , 1n a nd ti ions have been studied in buffer aqueous solutions of ph 5.0 at 2s°c by a spectrophotometric technique. the conditional stepwise stability constants of the resulting 1:l and 1:2 (metal-to-ligand) complexes were determined from the absorbance-mole ratio data at three different wavelengths of the visible spectra. the o...

A new tris-(2-aminoethyl)amine (TREN) capped tripodal Schiff base ligand has been developed by mimicking structural features of a natural siderophore, Bacillibactin, by substituting the catechol units with salicylaldehyde and employing amino acid as spacer. Synthesis of the ligand N-[2-[bis[2-[[2-[(2-hydroxyphenyl)methylamino]acetyl] amino]ethyl]amino]ethyl]-2-[(2-hydroxyphenyl)methylamino]...

We prove that the study of stability using energy methods strongly depends on the conservation laws considered. We exemplify this by studying stability using Arnold’s method in the case of so(4) free rigid body. Using the classical Mishchenko’s constants of motion we do not obtain satisfactory stability results. We find new constants of motion generated by Mishchenko’s first integrals that give...

Internal stability of isotropic nonlinear elastic materials under homogeneous deformation is studied. Results provide new insight into various intrinsic stability measures, first proposed elsewhere, for generic nonlinear elastic solids. Three intrinsic stability criteria involving three different tangent elastic stiffness matrices are considered, corresponding to respective increments in strain...

heterogeneous catalytic hydrogenation of cyclohexene, catalyzed by pt/a1203, was carried out in thirteenvarious solvents (four alcoholic solvents, six aprotic polar solvents and three non polar solvents) at 25 °c.single-parameter correlations of logk vs. normalized polarity parameter (etn), hydrogen-bond acceptorbasicity (p), hydrogen-bond donor acidity (a) and dipolarity/polarizibility (it*) d...

the formation constants of the species formed in the systems h+ + mo(vi) + histidine and h+ +histidine have been determined at different aqueous solutions of methanol (0 - 45 % v/v) at 25 °c andconstant ionic strength (0.1 mol dm-3 sodium perchlorate), using a combination of spectrophotometricand potentiometric techniques. the composition of the complex species was determined by thecontinuous v...

The protonation equilibria of four substituted N-methylbenzenesulfonamides, X-MBS: X = 4-MeO (3a), 4-Me (3b), 4-Cl (3c) and 4-NO(2) (3d), in aqueous sulfuric acid were studied at 25 °C by UV-vis spectroscopy. As expected, the values for the acidity constants are highly dependent on the electron-donor character of the substituent (the pK(BH+) values are -3.5 ± 0.2, -4.2 ± 0.2, -5.2 ± 0.3 and -6....

NBO analysis, hybrid density functional theory (B3LYP/6-311+G**) based methods were used to study the anomeric effects (AE), Stereoelectronic interactions, dipole-dipole interactions on the conformational properties of 1-Fluoro-N, N-dimethylmethanamine (1) and phosphorus (2) and arsenic (3) analogues.Moreover, relationships between stability of the anti-conformations of 1-Fluoro-N, N-dimethylme...

A critical analysis of the conditions elastic stability crystal structures different symmetry as restrictions imposed on their constants c ij has been carried out. It is shown that all crystals, except for cubic ones, are described by polynomials from second to sixth powers . Necessary and sufficient crystals presented explicitly. Keywords: Elastic stability, Symmetry, constants, Stability cond...