P-containing Ligands Research Articles

Current Development of Pd(II) Complexes as Potential Antitumor Agents

Research has proven that the most effective and widely used metal-containing chemotherapy anticancer drugs are cisplatin ([cis-PtCl(2)(NH(3))(2)]) and many platinum complexes, however, these compounds have significant disadvantages including poor water solubility and serious side effects. Thus researches in order to overcome these shortcomings have never interrupted. Many non-platinum complexes have been synthesized and tested, in which some palladium complexes show significant antitumor activity in normal tumor cells and lower resistance of tumor cells to clinical treatments as well as lower side effects. Mononuclear palladium complexes with aromatic N-containing ligands, amino acid ligands, S-donor ligands, and P-containing ligands have respective qualities and properties due to the different structures and properties of the ligands; some dinuclear palladium complexes possess interesting steric structures and good antitumor activity; a try to modify natural medicines with Pd(2+) leads the research to a new route. In this review, medicinal chemistry, the development status and interactions of palladium complexes with DNA are discussed in order to provide guidance and determine structure and antitumor activity relationships for continuing studies of these systems.

Carbonylation of ethanol using Ni-isoquinoline complex catalyst: Activity and selectivity studies

The carbonylation of ethanol using NiCl 2 · 6H 2O/isoquinoline catalyst system and aqueous HI as a promoter has been investigated. Effect of catalyst, ethanol and HI concentration, temperature, partial pressures of CO and H 2, N- or P-containing ligands and co-catalysts on the activity and selectivity has been studied. The Ni catalysts were found to be active only in the presence of N- or P-containing ligands. LiI and NaI were found to further enhance the catalytic activity without affecting the selectivity. Activity of Ni-isoquinoline-HI catalyst was found to be constant even after 4 recycles indicating high stability.

Zinc sequestration by earthworm (Annelida: Oligochaeta) chloragocytes

The elemental compositions of chloragosome "granules" in the earthworm Lumbricus rubellus living in non-polluted and heavily Zn-polluted soils were determined by fully quantitative electron probe X-ray microanalysis. P, Ca, S and Zn were the major elemental components of the chloragosomes. The in vivo accumulation of Zn by the chloragosomes was accompanied by diminished chloragosomal Ca concentrations. Zn was apparently bound by at least two ligand pools (Pool 1 = uncharacterised; Pool 2 = P-containing ligands, binding approximately 45% and 55% of the Zn, respectively) in the "control" chloragosomes. In Zn-contaminated chloragosomes, most (approximately 70%) was bound by P-containing ligand(s) but some (less than 1%) was also bound by S-containing ligands. It is suggested that the sequestration of Zn in chloragosomes results in the detoxification of the metal by accumulative immobilisation.

Carbonylation of ethanol using homogeneous Ir complex catalyst: effect of ligands and reaction conditions

Carbonylation of ethanol using IrCl 3 · 3H 2O as catalyst precursor with HI as a promoter is reported. The role of N- and P-containing ligands and solvents, and the influence of reaction conditions on the activity and selectivity is discussed. The average activity vs. HI concentration showed an unusual trend with a maximum. The water-gas shift reaction was found to be significant above 483 K and at higher concentrations of HI (⪢1.12 × 10 −3 mol cm −3).

Effects of cyanide and polyphosphates on adsorption of metals from simulated and real mixed-metal plating wastes

This study evaluated the effects of chromate, cyanide, pyrophosphate and tripolyphosphate on the adsorption of a suite of metals (Cd, Cu, Cr, Zn, Ni and Pb) onto iron oxyhydroxide. All metals were present simultaneously, along with one of the anions. In the absence of complexing agents, adsorption of the strongest sorbing metals (Pb, Cu, Cr) slightly inhibited that of the remaining metals when all were present at concentrations of 10 −4 M and 10 −3 M total iron was available as the adsorbent. The presence of up to 10 −3 M CrO 4 had no significant effect on removal of the cationic metals from solution. Cyanide strongly inhibited sorption of Ni and Cu, but did not affect the other metals. These effects can be explained based on changes in metal speciation when the CN was added. Under the experimental conditions, CN formed strong soluble complexes with Ni. Also, reduction of Cu 2+ to Cu + by CN, and subsequent formation of Cu +-CN complexes, was thermodynamically favorable. The remaining metals in the system did not form strong complexes under the experimental conditions and were therefore unaffected. At low concentration, pyro- and tripolyphosphate enhanced sorption of all the metals, but at high concentration they led to a qualitative change in the metal sorption behavior. Whereas in the absence of the phosphate ligands, metal sorption is strongly pH dependent, at high polyphosphate concentration, this dependence almost disappears. Simultaneously, some of the Fe adsorbent dissolves as Fe-P complexes. The changes in metal behavior with increasing ligand concentration reflect the the totality of interactions in the system, which includes complexation, adsorption of free metal and complexes, iron dissolution and changes in the surface charge associated with the various sorption reactions. The effects of metal, chromate and CN concentration do not appear to be major impediments to the utilization of adsorption as a treatment process. The effects of P-containing ligands are more complicated: they may either increase or decrease metal sorption depending on the particular water under study. Further study to elucidate the interactions in these latter systems appears warranted.