Volume 38, Issue 5-6

By the reaction of (dimethylphosphoryl)methanamine ( dpma ) with one equivalent of zinc(II) chloride in a hydrochloric acid solution and subsequent slow evaporation of the solvent, the title compound dpma HZnCl 3 was obtained in almost quantitative yield. The reaction product mainly consists of brick-shaped colorless crystals. Additionally, some smaller cuboid colorless crystals could be separated from the mother liquor. Structure analyses of two differently shaped crystals revealed that the block-shaped crystals 6a show a monoclinic diffraction pattern with the space group P 2 1 / c , whereas the cuboid-shaped crystals 6b possess tetragonal symmetry with the non-centrosymmetric space group P 4 1 . Both crystal structures consist of zwitterionic dpma HZnCl 3 complexes containing the cationic dpma H + ligand, which coordinates the zinc metal center through its oxygen atom. One more common feature of both structures is an intramolecular N-H···Cl hydrogen bond that fixes the conformation about the central P-C bond of the dpma H + ligand. The polymorphs differ with regard to their intermolecular hydrogen bonding schemes. In the structure of polymorph 6a , one out of the two chlorido ligands, not involved in the intramolecular hydrogen bond, forms two N-H···Cl hydrogen bonds to aminium groups of two adjacent complexes, whereas the third chlorido ligand is uninvolved in any classical hydrogen bonding. This connection scheme constructs layers in the ab plane. In the crystal structure of polymorph 6b , both chlorido ligands that are not involved in the intramolecular hydrogen bond form intermolecular NH···Cl connections. This connectivity scheme results in one-dimensional polymers running perpendicular to the c direction. Common to both structures is that each aminium group form three unbifurcated N-H···Cl hydrogen bonds.

In the present study, CuO, polypyrrole (PPy), and CuO/PPy nanocomposites were synthesized to compare the selective adsorption behavior of hazardous metal ions such as Pb(II) ions. The synthesized nanomaterials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller surface area analysis, and energy dispersive X-ray spectroscopy. The adsorption studies clearly showed that CuO/PPy nanocomposites exhibited much higher adsorption performance than individual CuO and PPy. Kinetic data followed the pseudo-second-order model. The equilibrium attained at 120 min and isotherm follows the order Sips>Langmuir>Freundlich. The adsorbed Pb(II) is desorbed using 0.1 m HCl. The adsorption-desorption studies conducted over six cycles illustrate the viability and repeated use of the adsorbent for the removal of Pb(II) from aqueous solutions. The adsorbent’s practical efficiency and usefulness were tested using real industrial wastewater, and 0.55 g/L of adsorbent is adequate for the complete removal of Pb(II). Cytotoxicity results show that CuO/PPy nanocomposites were biocompatible at lower concentrations, and they were used as an ecofriendly nanoadsorbent for industrial and environmental applications.

A novel lead (II) complex of Schiff base containing three bipyridine units was synthesized by the template reaction between a new amine compound, 6-methyl-6′-(2-aminophenoxymethyl)-2,2′-bipyridine, and 2,2′-bipyridine-6,6′-dicarboxaldehyde in the presence of a Pb(II) perchlorate ion. The new amino compound and Schiff base complex, [Pb L ](ClO 4 ) 2 ·2H 2 O, were characterized by using matrix-assisted laser desorption/ionization with time-of-flight mass spectroscopy, FAR FT-IR, UV/visible spectroscopy, 1 H NMR, elemental analyses (CHN), and molar conductivity measurements. Then the synthesized complex was screened in vitro for its antibacterial and antifungal activities against three Gram-negative and two Gram-positive bacteria and also against Candida albicans as a fungus by the microdilution broth method as a minimal inhibitory concentration. [Pb L ](ClO 4 ) 2 ·2H 2 O exhibits moderate activity on Staphylococcus aureus and Listeria monocytogenes when compared with standard drug and also shows moderate antifungal activity on the fungus Candida albicans.

Several new monobutyltin(IV) derivatives containing both oximes and N-protected amino acids have been generated. The compounds having the general formulae BuSn[(L) 2 A], where LH=cyclohexanoneoxime, acetophenoneoxime and (where R=-CH(CH 3 ) 2 , -CH(CH 3 )CH 2 CH 3 , -CH 2 C 6 H 5 ), and BuSn[L(A) 2 ], where LH=cyclohexanoneoxime, acetophenoneoxime and (where R=-CH(CH 3 ) 2 , -CH(CH 3 )CH 2 CH 3 , -CH 2 C 6 H 5 ), were generated by the reactions of monobutyltin(IV) trichloride with sodium salts of oximes and N-protected amino acids in 1:2:1 and 1:1:2 molar ratios in dry boiling benzene. Plausible structures of these compounds were suggested based on physico-chemical and spectroscopic studies. 119 Sn NMR spectroscopic data revealed the presence of five and six coordinated tin centers.

Three tricyclohexyltin aryloxyacetates, p -YC 6 H 4 OCH 2 COOSn(C 6 H 11 - c ) 3 (where Y=H, 1 ; CHO, 2 ; CH 2 OH, 3 ), have been synthesized and characterized by means of elemental analysis, IR, and NMR ( 1 H, 13 C, and 119 Sn) spectroscopy. The crystal structures of complexes 1 and 3 are determined by X-ray single-crystal diffraction. The carboxylate in the compounds is monodentate. The tin atom of compound 1 adopts distorted tetrahedral coordination geometry. In the crystal lattice of compound 3 , there is a four-coordinated tin and a five-coordinated tin in which the fifth coordination site is occupied by a water molecule, and the molecules are linked by R 3 3 (30) and R 5 5 (28) hydrogen bonds into a two-dimensional supramolecular network. Bioassay results have shown that the compounds have good in vitro antibacterial activity against Escherichia coli .

Reaction of an extremely bulky potassium amide complex, KL † (L † =[Ar † (PPh 2 )N] - , Ar † =C 6 H 2 {C(H)Ph 2 } 2 Pr i -2,6,4), with GeCl 2 ·dioxane afforded low yields of the phosphinoamido and phosphinoamino germanium(II) chloride complexes, [GeCl 2 (κ 1 - P -L † GeCl)] and [GeCl 2 (κ 1 - P -L † H)], respectively. The X-ray crystal structures, and limited spectroscopic data, for the complexes are reported. Both complexes represent rare examples of phosphine adducts of GeCl 2 .

The isolation and molecular structure of bis(di- iso -propoxyphosphonyl)-4- tert -butyl]phenyl}tin triphenylphosphane perchlorate chromium pentacarbonyl, 2 , is reported. It is the first example of an ionic compound containing an organostannylene transition metal complex cation stabilized by a phosphane donor. Slow reaction of compound 2 in acetonitrile gave trans -bis-triphenylphosphane chromium tetracarbonyl, trans -(Ph 3 P) 2 Cr(CO) 4 , in a new crystalline modification.