Solubility and Ionic Processes in the Cu X 2? MX ?H2O ( X ?=Cl?, Br?; M +=Li+, Na+, K+, NH4+, Cs+) Systems

Summary.  Solubility isotherms in the CuBr₂−MBr−H₂O (M ⁺ = Li⁺, Na⁺, Cs⁺) systems at 298.15 K were measured. The results together with other available literature data for copper chloride and bromide systems were treated by hydration analysis, and comparative discussion of ionic processes taking place in the respective saturated solutions was performed. Corresponding author. E-mail: jitka@prfdec.natur.cuni.cz Received August 6, 2002; accepted (revised) November 29, 2002 Published online April 3, 2003     

Solubility and Ionic Processes in the Cu X 2? MX ?H2O ( X ?=Cl?, Br?; M +=Li+, Na+, K+, NH4+, Cs+) Systems

 Solubility isotherms in the CuBr₂−MBr−H₂O (M ⁺ = Li⁺, Na⁺, Cs⁺) systems at 298.15 K were measured. The results together with other available literature data for copper chloride and bromide systems were treated by hydration analysis, and comparative discussion of ionic processes taking place in the respective saturated solutions was performed.     

Anion influence on the solution-solid phase equilibria in the MX<Subscript>2</Subscript>-NEt<Subscript>4</Subscript>X-H<Subscript>2</Subscript>O systems (M = Cd,Cu, Co; X = Cl,Br) at 25°C

Solubility of the ternary systems M-NEt₄Cl-H₂O (M = Cd, Cu, Co) at 25°C was determined by the method of isothermal saturation. Compositions and fields of crystallization of solid compounds in equilibrium with a liquid phase were determined. Changes in the processes of hydration, association of tetraethyl ammonium salts, and acido-complex formation of d-element ions on the replacement of a halide anion affect the solution-solid phase equilibria in the studied systems.     

Structure of complex bromides crystallizing in MBr<Subscript>2</Subscript>-NEt<Subscript>4</Subscript>Br-H<Subscript>2</Subscript>O systems (M = Cd,Cu, Co) at 25°C

The crystalline structures of four tetraethylammonium salts, [Et₄N]CdBrP₃, [Et₄N]Cd₂Br₅, [Et₄N]₂CoBr₄, and [Et₄N]₂CuBr₄ were determined by X-ray analysis of their single crystals. The CdBr _x ^{2 − x} anions in the examined salts are linked to polymeric chains, and the coordination number of cadmium ion is 5 or 6. The d-metal ion in the copper and cobalt complexes has tetrahedral configuration, and the corresponding anions are discrete.     

Spherical particle Brownian motion in viscous medium as non-Markovian random process

The Brownian motion of a spherical particle in an infinite medium is described by the conventional methods and integral transforms considering the entrainment of surrounding particles of the medium by the Brownian particle. It is demonstrated that fluctuations of the Brownian particle velocity represent a non-Markovian random process. The features of Brownian motion in short time intervals and in small displacements are considered.     

Ambidentate coordination of dimethyl sulfoxide in rhodium(III) complexes

The two dimethyl sulfoxide solvated rhodium(III) compounds, [Rh(dmso-κO)(5)(dmso-κS)](CF(3)SO(3))(3) (1 & 1* at 298 K and 100 K, respectively) and [Rh(dmso-κO)(3)(dmso-κS)(2)Cl](CF(3)SO(3))(2) (2), crystallize with orthorhombic unit cells in the space group Pna2(1) (No. 33), Z = 4. In the [Rh(dmso)(6)](3+) complex with slightly distorted octahedral coordination geometry, the Rh-O bond distance is significantly longer with O trans to S, 2.143(6) ? (1) and 2.100(6) ? (1*), than the mean Rh-O bond distance with O trans to O, 2.019 ? (1) and 2.043 ? (1*). In the [RhCl(dmso)(5)](3+) complex, the mean Rh-O bond distance with O trans to S, 2.083 ?, is slightly longer than that for O trans to Cl, 2.067(4) ?, which is consistent with the trans influence DMSO-κS > Cl > DMSO-κO of the opposite ligands. Raman and IR absorption spectra were recorded and analyzed and a complete assignment of the vibrational bands was achieved with support by force field calculations. An increase in the Rh-O stretching vibrational frequency corresponded to a decreasing trans-influence from the opposite ligand. The Rh-O force constants obtained were correlated with the Rh-O bond lengths, also including previously obtained values for other M(dmso)(6)(3+) complexes with trivalent metal ions. An almost linear correlation was obtained for the MO stretching force constants vs. the reciprocal square of the MO bond lengths. The results show that the metal ion-oxygen bonding of dimethyl sulfoxide ligands is electrostatically dominated in those complexes and that the stretching force constants provide a useful measure of the relative trans-influence of the opposite ligands in hexa-coordinated Rh(III)-complexes.     

The stress-related production of the activePhotinus pyralis and luciolaMingrelica firefly luciferases inEscherichia coli

The kinetics ofPhotinus pyralis andLuciola mingrelica luciferase gene expression was studied on plasmids with the thermoinducible λP_r promoter inEscherichia coli by SDS-gel electrophoresis of cell lysates to follow luciferase protein-synthesized, enzyme immunoassay (EIA) to follow native enzyme conformer, and the luciferase activity assay.E. coli cells were cultivated at temperature schemes 28–42–21°C or 28–21°C, or at alkali pH shift. In the cases of thermoinduction and pH shift, the luciferase expressions have similar features. The 3-h thermoinduction (42°C) followed by the incubation at 21°C, for 10 h resulted in the maximal amount of the luciferase protein of 4–5% of the total cell proteins. The yield did not change further. The amount of native luciferase conformer and the luciferase activity started to grow after incubation for 10 h at 21°C and reached the maximum after 50–60 h when the synthesized luciferase protein adopted the native-like conformation. At the same time, only 50% of the latter appeared to be catalytically active. An increase in the enzymatic activity correlates with an increase in the intracellular pH and ATP content. Intracellular metabolic reactions were shown to play a role in the conformational changes of the enzyme in a postthermoinduction period, and a possible mechanism of this effect is proposed.