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Herein we report the synthesis and characterization of a linear, two-coordinate Pt(II) ketimide complex, Pt(N═CtBu2)2 (1), formed via the reaction of PtCl2(1,5-COD) with 2 equiv of Li(N═CtBu2). Also generated in the reaction is the bimetallic complex [(tBu2C═N)Pt(μ-N,C-N═C(tBu)C(Me)2CH2)Pt(N═CtBu2)] (2). Both complexes 1 and 2 have been characterized by NMR spectroscopy and X-ray crystallography. Notably, complex 1 exhibits short Pt-N distances (av. Pt-N = 1.817 Å) and an unusually deshielded 195Pt chemical shift (δPt = -629 ppm) with a large 1J(195Pt,14N) coupling constant (537 Hz). These data, in combination with a detailed density functional theory electronic structure analysis, reveal the presence of highly covalent Pt═N multiple bonds formed by a combination of σ-donation, π-donation, and π-backdonation.

Several novel copper (II) complexes of reduced Schiff bases containing fluoride substituents were prepared and structurally characterized by single-crystal X-ray diffraction. The complexes exhibited diverse structures, with the central atom in distorted tetrahedral geometry. The biological effects of the products were evaluated, specifically their cytotoxicity, antimicrobial, and antiurease activities, as well as affinity for albumin (BSA) and DNA (ct-DNA). The complexes showed marked cytotoxic activities in the HepG2 hepatocellular carcinoma cell line, considerably higher than the standard cisplatin. The cytotoxicity depended significantly on the substitution pattern. The best activity was observed in the complex with a trifluoromethyl group in position 4 of the benzene ring—the dichloro[(±)-trans-N,N′-bis-(4-trifluoromethylbenzyl)-cyclohexane-1,2-diamine]copper (II) complex, whose activity (IC50 28.7 μM) was higher than that of the free ligand and markedly better than the activity of the standard cisplatin (IC50 336.8 μM). The same complex also showed the highest antimicrobial effect in vitro. The affinity of the complexes towards bovine serum albumin (BSA) and calf thymus DNA (ct-DNA) was established as well, indicating only marginal differences between the complexes. In addition, all complexes were shown to be excellent inhibitors of the enzyme urease, with the IC50 values in the lower micromolar region. [ABSTRACT FROM AUTHOR]

Multi‐functional polymers used for personal care products can be synthesized by radical polymerization of acrylic acid (AA) in alcohol/water solutions with non‐functional monomers such as methyl acrylate (MA) and N‐tert‐butylacrylamide (t‐BuAAm). However, solvents capable of forming or disrupting hydrogen bonds cause the polymerization kinetics of these monomers to deviate from their polymerization behaviour in bulk and non‐polar solvents. In this work, a previous mechanistic model developed for MA/t‐BuAAm copolymerization is extended to represent the terpolymerization system MA/t‐BuAAm/AA. The additional kinetic coefficients required for the system are estimated from fitting to AA homopolymerizations and AA/MA and AA/t‐BuAAm copolymerizations conducted in an ethanol/water solution. In‐situ nuclear magnetic resonance (NMR) spectroscopy is used to follow monomer conversions and composition drift behaviour, with the molar mass distributions of the polymer products characterized by size‐exclusion chromatography. Although AA is more reactive than MA in non‐polar solvents, the reactivities of the two monomers equalize under the experimental conditions examined. Thus, the batch and semi‐batch terpolymerization data collected are represented equally well by a reduced acrylate/t‐BuAAm copolymerization model and the full terpolymerization implementation. [ABSTRACT FROM AUTHOR]

Diastereoselective ortho-lithiation of ferrocenes is a principal strategy for the synthesis of chiral ferrocene ligands. Dilithiation of ( R)-1-(2-bromophenyl)-1-ferrocenyl- N, N-dimethylmethanamine leads to a dilithium intermediate, which can be transformed to a Taniaphos ligand with ( R, Rp)-configuration. On the other hand, lithiation of ( R)-1-phenyl-1-ferrocenyl- N, N-dimethylmethanamine affords a lithiated product with opposite configuration of the stereogenic plane. Presumably, the second lithium atom attached at the ortho-position of the phenyl ring is responsible for this difference through the intramolecular multicenter arrangement involving both lithium atoms and their adjacent carbon atoms, the iron atom of the ferrocenyl moiety, and the nitrogen atom of the amino group. This hypothesis has been supported also by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

The diastereoselectivity of [3+2] cycloaddition of tricarbonyl[(4,5,6,7-η)-2-methyltropone]iron (2) with an E,Z isomeric mixture of η1-(crotyl)Fp (4E/4Z) [Fp: C5H5Fe(CO)2 or CpFe(CO)2] has been studied. By this cyclopentaanulation, four stereogenic centres are formed. The reaction occurs regioselectively and stereoselectively. The relative configurations of the cycloadducts 5a, 5b and 5c were assigned on the basis of 2D and NOE NMR experiments. A mechanism for the stereoselective [3+2] cycloaddition has been proposed. The selectivity of the cycloaddition depends on the difference in steric discrimination approaches of the η1-(crotyl)Fp 4E/4Z to the tricarbonyl[(3,4,5,6,7-η)-1-trimethylsilyloxy-2-methyltropylium]iron 3 (repulsion of the methyl and methylene groups of 4 and the planar skeleton of 3) and also upon the isomeric structure (E or Z) of the η1-(crotyl)Fp reactant. The geometrical isomerism of the reagent (4E/4Z) is preserved in the products 5a–c. [Copyright &y& Elsevier]

Abstract: In this study, we demonstrate the synthesis of the [Al13O4(OH)24(H2O)12]7+ Keggin ε-Al13 ion by a mechanochemical reaction between [Al(H2O)6]Cl3 and (NH4)2CO3 reactants. Five grams of the starting mixture corresponding to a molar ratio of (NH4)2CO3/[Al(H2O)6]Cl3 =0.45:2, 1:2, 1.5:2, 2:2, 2.25:2, 2.55:2 and 3:2 was milled for 5min. The existence of ε-Al13 was observed at molar ratios of (NH4)2CO3/[Al(H2O)6]Cl3 =2:2 and higher. Our results show that more than 50% mass of Al from a starting [Al(H2O)6]Cl3 was bonded to the polymeric [Al13O4(OH)24(H2O)12]7+ ionic form at a molar ratio of 2.55:2. [Copyright &y& Elsevier]

The paper deals with the isolation and identification of the constituents of Cornus officinalis Sieb. et Zucc. leaves. There was isolated β-sitosterol from petroleum ether extract, glucose and saccharose from methanolic extract and gallic acid, quercetin and quercetin-3-O-glucoside (isoquercitrin) from aqueous-methanolic extract. Isolates were identified by physico-chemical data, and by comparing with authentic samples and literature data. The compounds I - V were isolated from the leaves of Cornus officinalis Sieb. et Zucc. for the first time.Key words: Cornus officinalis Sieb. et Zucc. Cornaceae petroleum ether extract methanolic extract aqueous-methanolic extract.

The (15)N as well as (13)C and (1)H chemical shifts of eight push-pull benzothiazolium iodides with various pi-conjugated chains between dimethylamino group and benzothiazolium moiety have been determined by NMR spectroscopy at the natural-abundance level of all nuclei in DMSO-d(6) solution. In general, the quaternary benzothiazolium nitrogen is more shielded [delta((15)N-3) vary between - 241.3 and - 201.9 ppm] with respect to parent 3-methylbenzothiazolium iodide [delta((15)N-3) = - 183.8 ppm], depending on the length and constitution of the pi-conjugated bridge. A larger variation in (15)N chemical shifts is observed on dimethylamino nitrogen, which covers the range of - 323.3 to - 257.2 ppm. The effect of pi-conjugation degree has a less pronounced influence on (13)C and (1)H chemical shifts. Experimental data are interpreted by means of density functional theory (DFT) calculations. Reasonable agreement between theoretical and experimental (15)N NMR chemical shifts was found, particularly when performing calculations with hybrid exchange-correlation functionals. A better accord with experiment is achieved by utilizing a polarizable continuum model (PCM) along with an explicit treatment of hydrogen-bonding between the solute and the water present in dimethylsulfoxide (DMSO). Finally, (13)C and (1)H NMR spectra were computed and analysed in order to compare them with available experimental data., ((c) 2007 John Wiley & Sons, Ltd.)