Hydrosilylation of Allylgermanes

Russian Journal of General Chemistry - The hydrosilylation reactions of allylgermanes R3GeAll (R3 = Cl3, Me3) in the presence of a platinum catalyst (Karstedt catalyst) with...     

Reactions of the biologically active palladium complexes (H<Subscript>2</Subscript>A)<Subscript>2</Subscript>[PdCl<Subscript>4</Subscript>] with glutamic acid as a model of their transformations in blood plasma

Complexation in the systems Pd(II)-Cl⁻-HA-H₂Glu (HA is the l- or d-conformer of 2-methylamino-1-phenylpropanol; H₂Glu is glutamic acid) was studied using pH-metric titration, electronic absorption spectroscopy, and quantum-chemical modeling. It was found that the ratio of the complex species largely depends on pH and the amine, the crucial factor being stabilization of the structures by hydrogen bonding. This provides explanation to the previous data on the different radioprotective activities of the complexes (H₂A)₂[PdCl₄] containing the l- and d-conformers of the ligand HA.     

Cation-anion palladium complexes: the effect of the hydrogen bond character on their stability and biological activity

The results of study of a new class of biologically active palladium complexes (AH _n ) _m [PdCl₄] have been reported. This class of compounds has been discovered by us on the basis of systemic research of composition-structure-biological activity relationships for different classes of platinum metal complexes. It has been shown that the stability of cation-anion palladium complexes and their biological activity are determined by the nature of protonated amines acting as cations and the acid-base properties of the cations-tetrachloropalladate anion systems, manifested in the character and stability of hydrogen bonds that appear in these systems. For the first time, it has been demonstrated in vivo that it is possible to synthesize palladium compounds superior to cisplatin in antitumor activity and not exhibiting immunosuppressive activity, as well as palladium compounds with immunostimulatory and radiomodifying activity. A combination of cytostatics used in oncology or irradiation with palladium complexes leads to significant synergism of their effects and to a considerably higher therapeutic efficiency of such combinations as compared with the treatment effect of each of them alone.     

Effects of palladium acido complexes [Ln]m[PdX4] on the conformation of DNA in vitro

The interactions of palladium cation-anion compounds (C₄H₁₀NO)₂[PdCl₄], K₂[PdCl₄], and K₂[PdBr₄] with DNA in 0.005 M NaCl and 0.15 M NaCl solutions were studied by spectrophotometry, circular dichroism, viscosimetry, dynamic birefringence, and atomic force microscopy. The interactions are primarily effected by coordination of the donor atoms of DNA bases by palladium. The end products of interactions with palladium acido complexes are independent of the macromolecule and the nature of halogen X in [PdX₄]₂₋. The significant changes in the conformation of DNA in palladium complexes resulted from both intra- and intermolecular cross-linkings induced by palladium.     

Synthesis and structure of palladium(II) mixed complexes with DNA purine or pyrimidine bases and imidazole derivatives. Part I

Summary Palladium(II) mixed ligand complexes with purine or pyrimidine and imidazole derivatives were prepared and characterized by i.r., Raman and electronic spectroscopy. The compounds have the general formula [Pd(L₁)(L₂)(X₂)]; where L₁ = adenine, guanine, hypoxanthine, cytosine, 2-aminopyrimidine, 4(6)-hydroxypyrimidine; L₂ = N-methylimidazole, N-ethylimidazole or N-propylimidazole; X = Cl or Br. The complexes are square planar with cis-halogens. The purine, pyrimidine and imidazole bases act as monodentate ligands coordinated via the N(7) of purine and N(3) of pyrimidine and imidazole.     

Synthesis and structures of platinum(II) mixed ligand complexes with purine or piyrimidine bases of DNA and imidazole derivatives. Part 2

Summary Platinum(II) mixed ligand complexes with either purine or pyrimidine and imidazole derivatives were prepared and characterized by i.r., Raman and electronic spectroscopy. The compounds had the general formula [PtL¹L²Cl₂], where L¹ = adenine, guanine, hypoxanthine, cytosine, 2-aminopyrimidine; L² =N-methylimidazole,N-ethyl-imidazole orN-propylimidazole. The platinum(II) complexes had a square planar structure withcis-halogens. Purine or pyrimidine and imidazole derivatived bases acted as monodentate ligands coordinated via the N(7) of purine and N(3) of pyrimidine and imidazole derivatives.     

Surface modification of Sylgard-184 poly(dimethyl siloxane) networks by ultraviolet and ultraviolet/ozone treatment

We report on the surface modification of Sylgard-184 poly(dimethyl siloxane) (PDMS) networks by ultraviolet (UV) radiation and ultraviolet/ozone (UVO) treatment. The effects of the UV light wavelength and ambient conditions on the surface properties of Sylgard-184 are probed using a battery of experimental probes, including static contact angle measurements, Fourier transform infrared spectroscopy, near-edge X-ray absorption fine structure, and X-ray reflectivity. Our results reveal that when exposed to UV, the PDMS macromolecules in the surface region of Sylgard-184 undergo chain scission, involving both the main chain backbone and the side groups. The radicals formed during this process recombine and form a network whose wetting properties are similar to those of a UV-modified model PDMS. In contrast to the UV radiation, the UVO treatment causes very significant changes in the surface and near-surface structure of Sylgard-184. Specifically, the molecular oxygen and ozone created during the UVO process interact with the UV-modified specimen. As a result of these interactions, the surface of the sample contains a large number of hydrophilic (mainly -OH) groups. In addition, the material density within the first approximately 5 nm reaches about 50% of that of pure silica. A major conclusion that can be drawn from the results and analysis described in this work is that the presence of the silica fillers in Sylgard-184 does not alter the surface properties of the UVO- and UV-modified Sylgard-184.