Coordination modes of 2-mercapto-1,3-benzothiazolate in gallium and indium complexes

2-Mercapto-1,3-benzothiazole (mbztH) may act as a chelating or bridging ligand. In this study, reactions of mbztH with Me₃Ga and Me₃In were examined. The products were characterized by NMR spectroscopy, elemental analyses, melting point, and molecular weight determinations. Formation of mononuclear chelating complexes Me₂M(mbzt) (M = Ga, In) was observed in solutions. Crystallization of Me₂M(mbzt) yielded uncommon non-symmetrical dinuclear complexes Me₄M₂(mbzt)₂, in which one metal is bonded to two sulfurs and the other to two nitrogens.     

Effects of Multi Global Bifurcations on Basin Organization,Catastrophes and Final Outcomes in a Driven Nonlinear Oscillator at the 2T-Subharmonic Resonance

The behavior of the escape driven oscillator at the 2T-periodic subharmonic resonance is considered, and the mechanism of generating different fractal patterns of the basins of attraction of coexisting attractors, as well as its effects on the unpredictable asymptotic system behaviors, are the main points of interest. The analysis is based on the numerical study of the sudden qualitative changes of the structure of basin-phase portraits, the changes implied by multi global bifurcations. Attention is focused on two qualitatively different regions of control space: the region prior to the subcritical flip bifurcation, where all three attractors (2T-periodic, T-periodic and the attractor at infinity) coexist, and the region after the bifurcation, where only two attractors (2T-periodic and the attractor at infinity) coexist. In particular, the concept of the global (homoclinic and heteroclinic) bifurcations is extended to the latter region, where the arising flip saddle (instead of the direct saddle) is involved in the events. The possible forms of unpredictable outcomes, which arise in both regions of control parameters, are pointed out.     

Orthobromodiphenylmethane Derivatives as Starting Materials for the Total Synthesis of Anthraquinones

In this communication we describe the synthesis of four simple anthraquinones by a five-step sequence, using easily available bromobenzaldehydes and phenyllithium derivatives as starting materials.     

Potentiometric Study of Lanthanide Salicylaldimine Schiff Base Complexes

Formation of complexes between the lanthanide ions and N,N′-bis(salicylidene)-4-methyl-1,3-phenylenediamine ligand was studied in solution by pH potentiometry. The potentiometric titration was performed at 25.00 °C in 0.1 mol·dm^?3 NaClO₄ ionic strength and in DMSO:water (30:70 v:v) solvent mixture. N,N′-bis(salicylidene)-4-methyl-1,3-phenylenediamine ligand (H₂L) occurs in three forms: fully or partially deprotonated and unionized. Computer analysis of potentiometric data indicated that in solution the lanthanide (Ln) complexes exist as LnL₂, Ln(HL)₂ and Ln(H₂L)₂ species. This observation appears to be in contrast to the solid-state behavior of these complexes prepared in a self-assembly process and structurally defined. Stability constants for La³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Ho³⁺ and Lu³⁺ (Ln³⁺) complexes were determined. The order of stabilities of LnL₂ species in terms of metal ions is La³⁺ > Eu³⁺ ≈ Gd³⁺ = Tb³⁺ < Ho³⁺ < Lu³⁺ with a prominent “gadolinium break”.     

Catalytic Oxidative Cyclocondensation of o‐Aminophenols to 2‐Amino‐3H‐phenoxazin‐3‐ones

The catalytic oxidative cyclocondensation of the o‐aminophenols 1a–f was investigated. The oxidants used were air/laccase, H₂O₂/horseradish peroxidase, H₂O₂/ebselen (3), and TBHP/diphenyl diselenide 4. The products obtained were 2‐amino‐3H‐phenoxazin‐3‐one—questiomycin A, its derivative 2b, and cinnabarinic acid and actinocin (2c,d). Substrates with methyl groups at 4 and 5 positions of benzene ring were converted to different dihydrophenoxazinones 2g,h. Compounds having chlorine atoms at the same positions underwent oxidation to planar phenoxa-zinones 2e,f with elimination of one hydrochloride molecule.     

Long-Term Cultured Hairy Roots of Chicory—A Rich Source of Hydroxycinnamates and 8-Deoxylactucin Glucoside

Foam fractionation is a promising method for separation and concentration of biochemicals. It is simple, easily scalable, inexpensive, and environment friendly. Foam fractionation thus represents an alternative to the traditional methods used for immunoglobulin enrichment. However, little, if any, literature exists documenting the utilization of foam fractionation in the enrichment of immunoglobulins. Milk were utilized as an immunoglobulin source to serve as examples of a real system in this study. The investigation examined the effects of varying five different process parameters: the initial pH value, the initial concentration of immunoglobulin, the nitrogen flow rate, the column height, and the foaming time. Experimental results demonstrated that immunoglobulin could effectively be enriched from milk by foam fractionation. The maximum enrichment ratio with pretreatment (using pH 4.6 precipitation) was 6.30 along with a more than 92 % recovery for IgG and an enrichment ratio of 5.1 with 85 % recovery for IgM.     

Calixarene complexes with metal ions

Selected complexes of metal ions are presented showing their syntheses and possible applications, an attention was paid to their usefulness in chemosensors design and in the environmental protection.     

Degradation Study of Polymers from Renewable Resources and their Compositions in Industrial Composting Pile

Summary: Polyesters produced from renewable resources and susceptible to hydrolysis under the industrial composting conditions offer ecological advantages as compared to thermoplastics polymers and elastomers produced from fossil carbon sources. In this paper the degradation behaviour of polymer compositions of BTA, PLA and a-PHB in natural environment of industrial composting pile, consisting of leaves - 40%, branches - 30% and grass - 30%, have been presented. The extend of degradation was monitored by macroscopic observations of sample surfaces, changes of molecular weight, polydispersity and composition of the tested materials and their weight loss.