Sequence determination of αs1‐casein isoforms from donkey by mass spectrometric methods

Four co‐eluting components, with experimentally measured M_r of 23 658, 23 786, 24 278 and 24 406 Da, were detected by reversed‐phase high‐performance liquid chromatography (RP‐HPLC) and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) analysis in the dephosphorylated casein fraction of a milk sample collected at middle lactation stage from an individual donkey belonging to the Ragusano breed. By coupling RP‐HPLC, two‐dimensional polyacrylamide gel electrophoresis (2D‐PAGE), enzymatic digestions, MALDI‐TOF MS and capillary RP‐HPLC/nano‐electrospray ionization tandem mass spectrometry (nESI‐MS/MS) analyses, the four components were identified as donkey's α_s1‐CNs and their sequences completely characterized, using the known mare's α_s1‐CN (GenBank Acc. No. AAK83668; M_r 23750.7 Da) as reference. The proteins with M_r of 23 786 and 23 658 Da differ in the presence of a glutamine residue at position 83 in the full‐length component and present the amino acid substitutions Q⁸→H and H¹¹⁵→Y with respect to the mare's α_s1‐CN. The other two components with M_r 24 406 and 24 278 Da, which also differ in the presence of a glutamine residue at position 88 in the full‐length component, show the insertion of the pentapeptide HTPRE between Leu³³ and the Glu³⁴. The two α_s1‐CNs bearing the pentapeptide insertion were named variants A (202 amino acids; M_r 24 406) and A₁ (201 amino acids; M_r 24 278), whereas the two α_s1‐CNs without the pentapeptide were named variants B (197 amino acids; M_r 23 786) and B₁ (196 amino acids; M_r 23 658). Copyright © 2009 John Wiley & Sons, Ltd.     

Oligonucleotide Analogues with Integrated Bases and Backbone. Part 16

The self‐complementary, ethylene‐linked U*[c_a]A⁽*⁾ dinucleotide analogues 8, 10, 12, 14, 16 , and 18 , and the sequence‐isomeric A*[c_a]U⁽*⁾ analogues 20, 22, 24, 26, 28 , and 30 were obtained by Pd/C‐catalyzed hydrogenation of the corresponding, known ethynylene‐linked dimers. The association of the ethylene‐linked dimers was investigated by NMR and CD spectroscopy. The U*[c_a]A⁽*⁾ dimers form linear duplexes and higher associates (K between 29 and 114M ^?1). The A*[c_a]U⁽*⁾ dimers, while associating more strongly (K between 88 and 345M ^?1), lead mostly to linear duplexes and higher associates; they form only minor amounts of cyclic duplexes. The enthalpy–entropy compensation characterizing the association of the U*[c_x]A⁽*⁾ and A*[c_x]U⁽*⁾ dimers (x=y, e, and a) is discussed.     

Dodecahydro‐nido‐undecaborate [B11H12]3–

The deprotonation of the nido‐anion [B₁₁H₁₄]^– by two equivalents of LitBu yields the anion [B₁₁H₁₂]^3–. Three observed ¹¹B NMR shifts of this anion in the ratio 1 : 5 : 5 are in agreement with shifts calculated by the GIAO method on the basis of the ab initio computed geometry. The deprotonation can be reversed, giving back [B₁₁H₁₄]^– via [B₁₁H₁₃]^2–. The thermolysis of [Li(thp)_x]₃[B₁₁H₁₂] in thp at 80 °C leads to the closo‐borate [Li(thp)₃]₂[B₁₁H₁₁] under elimination of LiH. Anhydrous air transforms [B₁₁H₁₂]^3– into the known oxa‐nido‐dodecaborate [OB₁₁H₁₂]^–. The rhoda‐closo‐dodecaborate [L₂RhB₁₁H₁₁]^3– is formed from [B₁₁H₁₂]^3– and RhL₃Cl (L = PPh₃).     

A simple RP‐HPLC method for quantification of columbianadin in rat plasma and its application to pharmacokinetic study

A rapid and sensitive reversed‐phase high‐performance liquid chromatographic (RP‐HPLC) method was developed to investigate pharmacokinetics of columbianadin, one of the main bioactive constituents in the roots of Angelica pubescens f. biserrata, in rat plasma after intravenous administration to rats at two doses of 10 and 20 mg/kg. The method involves a plasma clean‐up step using liquid–liquid extraction by diethyl ether, followed by RP‐HPLC separation and detection. Separation of columbianadin was performed on an analytical Diamonsil? ODS C₁₈ column, with a mobile phase of MeOH–H₂O (85 : 15, v/v) at a flow‐rate of 1.0 mL/min, and UV detection was set at 325 nm. The retention time of columbianadin and scoparone (internal standard) was 6.7 and 3.5 min, respectively. The calibration curve was linear over the range of 0.2–20.0 μg/mL (r² = 0.9986) in rat plasma. The lower limits of detection and quantification were 0.05 and 0.1 μg/mL, respectively. The extraction recovery from plasma was in the range of 81.61–89.93%. The intra‐ and inter‐day precisions (relative standard deviation) were between 1.01 and 9.33%, with accuracies ranging from 89.76 to 109.22%. The results indicated that the method established was suitable for the determination and pharmacokinetic study of columbianadin in rat plasma. Copyright © 2009 John Wiley & Sons, Ltd.     

Quantification of oxyresveratrol analog trans-2,4,3',5'-tetramethoxystilbene in rat plasma by a rapid HPLC method: application in a pre-clinical pharmacokinetic study

A rapid HPLC method was developed and validated for the quantification of oxyresveratrol analog trans‐2,4,3′,5′‐tetramethoxystilbene (oxyresveratrol tetramethyl ether, OTE) in rat plasma. Chromatographic separation was achieved on an RP‐HPLC column, which was protected by a guard column through a 12 min gradient delivery of a mixture of acetonitrile–water at 50°C. The UV absorbance at 325 nm was recorded. The retention time of OTE and trans‐stilbene (internal standard) was about 7.7 and 8.4 min, respectively. The calibration curves were linear (R² ≥ 0.9986) with a lower limit of quantification of 15 ng/mL. The intra‐ and inter‐day variations, in terms of RSD, were all lower than 9.8% while the intra‐day and inter‐day bias ranged from ?8.3 to +9.2%. The pharmacokinetics of OTE was assessed in rats using 2‐hydroxypropyl‐β‐cyclodextrin as a dosing vehicle. After intravenous administration, OTE possessed a long terminal elimination half‐life (t_{1/2 λz} = 481 ± 137 min) and slow clearance (Cl = 29.1 ± 3.7 mL/min/kg). Upon oral administration, OTE was rapidly absorbed. However, it only displayed minimal plasma exposure and its absolute oral bioavailability (F) was as low as 4.5 ± 3.2%. Fortunately, the levels of OTE after single oral administration were sufficient to inhibit human cytochrome P450 1B1. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneous RP‐HPLC‐DAD quantification of bromocriptine,haloperidol and its diazepane structural analog in rat plasma with droperidol as internal standard for application to drug‐interaction pharmacokinetics

A simple and rapid RP‐HPLC‐DAD method was developed and validated for simultaneous determination of the dopamine antagonists haloperidol, its diazepane analog, and the dopamine agonist bromocriptine in rat plasma, to perform pharmacokinetic drug‐interaction studies. Samples were prepared for analysis by acetonitrile (22.0 μg/mL) plasma protein precipitation with droperidol as an internal standard, followed by a double‐step liquid‐liquid extraction with hexane : chloroform (70:30) prior to C‐18 separation. Isocratic elution was achieved using a 0.1% (v/v) trifluoroacetic acid in deionized water, methanol and acetonitrile (45/27.5/27.5, v/v/v). Triple‐wavelength diode‐array detection at the λ_max of 245 nm for haloperidol, 254 nm for the diazepane analog and droperidol, and 240 nm for bromocriptine was carried out. The LLOQ of DAL, HAL, and BCT were 45.0, 56.1, and 150 ng/mL, respectively. In rats, the estimated pharmacokinetic parameters (i.e., t_1/2, CL, and V_ss) of HAL when administered with DAL and BCT were t_1/2 = 16.4 min, V_ss = 0.541 L/kg for HAL, t_1/2 = 28.0 min, V_ss = 2.00 L/kg for DAL, and t_1/2 = 24.0 min, V_ss = 0.106 L/kg for BCT. The PK parameters for HAL differed significantly from those previously reported, which may be an indication of a drug‐drug interaction. Copyright © 2009 John Wiley & Sons, Ltd.     

Novel copper(II) heterochelate: synthesis,structural features and fluorescence studies

Fluorescence properties of four based derivatives [Aⁿ] (where n = 1–4) and their Cu(II) heterochelates of the type [Cu(Aⁿ)(CQ)(OH)]^?xH₂O {where A¹ = 3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one, A² = 8‐methyl‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one, A³ = 6‐methyl‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one, A⁴ = 8‐chloro‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one and x = 3, 2, 4, 1} were studied at room temperature. The fluorescence spectra of heterochelates show red shift, which may be due to the chelation by the ligands to the metal ion. It enhances ligand ability to accept electrons and decreases the electron transition energy. The kinetic parameters such as order of reaction (n), energy of activation (E_a), entropy (ΔS^#), pre‐exponential factor (A), enthalpy (ΔH^#) and Gibbs free energy (ΔG^#) have been reported. The antimicrobial activity of Clioquinol and Cu(II) heterochelates have been determined and described. All the heterochelates showed a more effective antimicrobial activity than the free ligand. Copyright © 2010 John Wiley & Sons, Ltd.     

Syntheses and X‐Ray Structures of Zinc Amidinate Complexes

Reactions of ZnX₂ (X = Cl, Br) with equimolar amounts of Li[t‐BuC(NR)₂] (R = i‐Pr, Cy) yielded mono‐amidinate complexes [{t‐BuC(NR)₂}ZnX]₂ (X = Cl, R = i‐Pr 1 , Cy 2 ; X = Br, R = i‐Pr 3 , Cy 4 ), whereas reactions with two equivalents of Li‐amidinate resulted in the formation of the corresponding bis‐amidinate complexes [t‐BuC(NR)₂]₂Zn (R = i‐Pr 5 , Cy 6 ). 1 ‐ 6 were characterized by elemental analyses, IR, mass and multinuclear NMR spectroscopy (¹H, ¹³C), and single crystal X‐ray analysis ( 1 , 2 , 3 , 6 ). In addition, the single crystal X‐ray structure of [t‐BuC(NCy)₂]ZnBr·LiBr(OEt₂)₂ 7 , which was obtained as a byproduct in low yield from re‐crystallization experiments of 4 in Et₂O, is reported.     

Novel drug‐based Fe(III) heterochelates: synthetic,spectroscopic, thermal and in‐vitro antibacterial significance

A series of novel heterochelates of the type [Fe(Aⁿ)(L)(H₂O)₂]^?mH₂O [where H₂Aⁿ = 4,4′‐(arylmethylene)bis(3‐methyl‐1‐phenyl‐4,5‐dihydro‐1H‐pyrazol‐5‐ol); aryl = 4‐nitrophenyl, m = 1 (H₂A¹); 4‐chlorophenyl, m = 2 (H₂A²); phenyl, m = 2 (H₂A³); 4‐hydroxyphenyl, m = 2 (H₂A⁴); 4‐methoxyphenyl, m = 2 (H₂A⁵); 4‐hydroxy‐3‐methoxyphenyl, m = 1.5 (H₂A⁶); 2‐nitrophenyl, m = 1.5 (H₂A⁷); 3‐nitrophenyl, m = 0.5 (H₂A⁸); p‐tolyl, m = 1 (H₂A⁹) and HL = 1‐cyclopropyl‐6‐fluoro‐4‐oxo‐7‐(piperazin‐1‐yl)‐1,4‐dihydroquinoline‐3‐carboxylic acid] were investigated. They were characterized by elemental analysis (FT‐IR, ¹H‐ & ¹³C‐NMR, and electronic) spectra, magnetic measurements and thermal studies. The FAB‐mass spectrum of [Fe(A³)(L)(H₂O)₂]^?2H₂O was determined. Magnetic moment and reflectance spectral studies revealed that an octahedral geometry could be assigned to all the prepared heterochelates. Ligands (H₂Aⁿ) and their heterochelates were screened for their in‐vitro antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Serratia marcescens bacterial strains. The kinetic parameters such as order of reaction (n), the energy of activation (E_a), the pre‐exponential factor (A), the activation entropy (ΔS^#), the activation enthalpy (ΔH^#) and the free energy of activation (ΔG^#) are reported. Copyright © 2009 John Wiley & Sons, Ltd.     

Validated Method for the Simultaneous Determination of Gemifloxacin and H2‐receptor Antagonists in Bulk,Pharmaceutical Formulations and Human Serum by RP‐HPLC; In‐vitro Applications

Simple, isocratic and rapid RP‐HPLC method has been developed for the simultaneous analysis of gemifloxacin and H₂‐receptor antagonists i.e. Cimetidine, Famotidine and Ranitidine, in bulk, pharmaceutical formulation and human serum. Separation was achieved on the RP‐Mediterranea column [C18 (250 × 4.6 mm, 5 μ)] at ambient temperature using mobile phase consisting of acetonitrile: methanol: water (20:28:52 v/v/v pH 2.8 adjusted by phosphoric acid). Flow rate was 1.0 mL/min with an average operating pressure of 180 kg/cm². Gatifloxacin (GATI) was used as an internal standard (IS). Quantitation was achieved with UV detection at 221, 256 and 267 nm, respectively. Linear calibration curves, at concentration ranges of 0.05‐37.5 μgmL^‐L with a correlation coefficient of ±0.9994. The detection and quantification limits were in the ranges of 0.023‐0.250 μgmL^‐L and 0.071‐0.756 μgmL^‐L, respectively. Friedman's and Student's t‐test were applied to correlate these results. Method was validated in terms of selectivity, linearity, precision, robustness, recovery, limits of detection and quantitation and is applicable to the routine analysis of GFX and H₂‐receptor antagonists, alone or in combination.     

Stereo‐dynamics of the F + HCl → HF + Cl reaction

We present a quasi‐classical trajectory (QCT) study on product polarization for the reaction F(²P) + HCl(v = 0, j = 0) → HF + Cl(²P) on a recently computed 1² A′ ground‐state surface reported by Deskevich et al. J Chem Phys, 2006, 124, 224303. Four polarization dependent generalized differential cross‐sections (2π/σ)(dσ₀₀/dω_t), (2π/σ)(dσ₂₀/dω_t), (2π/σ)(dσ₂₂₊/dω_t), and (2π/σ)(dσ_21?/dω_t) were calculated in the center‐of‐mass frame at four different collision energies. The obtained P(θ_r), P(?_r), and P(θ_r, ?_r), which denote respectively the distribution of angles between k and j′, the distribution of dihedral angle denoting k‐k′‐j′ correlation and the angular distribution of product rotational vectors in the form of polar plots, indicate that the degree of rotational alignment of the product HF molecule is strong and the degree of the rotational alignment decreases as collision energy increases. The product rotational angular momentum vector j′ is not only aligned, but also oriented along the y‐axis, and the molecular rotation of the product prefers an in‐plane reaction mechanism rather than the out‐of‐plane mechanism. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Octanol/water partitioning simulation by RP‐HPLC for structurally diverse acidic drugs: Comparison of three columns in the presence and absence of n‐octanol as the mobile phase additive

The advantageous effect of n‐octanol as a mobile phase additive for lipophilicity assessment of structurally diverse acidic drugs both in the neutral and ionized form was explored. Two RP C₁₈ columns, ABZ⁺ and Aquasil, were used for the determination of logk_w indices, and the results were compared with those previously reported on a base‐deactivated silica column. At pH 2.5, the use of n‐octanol‐saturated buffer as the mobile phase aqueous component led to high‐quality 1:1 correlation between logk_w and logP for the ABZ⁺ column, while inferior statistics were obtained for Aquasil. At physiological pH, the correlations were significantly improved if strongly ionized acidic drugs were treated separately from weakly ionized ones. In the latter case, 1:1 correlations between logD_7.4 and logk_w^oct indices were obtained in the presence of 0.25% n‐octanol. Concerning strongly ionized compounds, adequate correlations were established under the same conditions; however, slopes were significantly lower than unity, while large negative intercepts were obtained. According to the absolute difference (diff = logD_7.4–logk_w) pattern, base‐deactivated silica showed a better performance than ABZ⁺, however, the latter seems more efficient for the lipophilicity assessment of highly lipophilic acidic compounds. Aquasil may be the column of choice if logD_7.4<3 with the limitation, however, that very hydrophilic compounds cannot be measured.     

Alternation Tendency in Copolymerization

The number fractions of the alternate diads and triads and the average length of the alternate sequence may be used as the indices of the alternation tendency of binary copolymerizations. It is shown that these indices take on maximum values when the monomer feed ratio is such that [M₁]/[M₂] = (r₂/r₁)^1/2. The physical significance of the customary measure of the alternation tendency r₁r₂ is discussed.     

Heterologous expression of human cytochrome P450 (CYP) 2C19 in Escherichia coli and establishment of RP‐HPLC method to serve as activity marker

In this study, a simple and reliable reverse‐phase high‐performance liquid chromatography (RP‐HPLC) method was established and validated to analyze S‐mephenytoin 4‐hydroxylase activity of a recombinant CYP2C19 system. This system was obtained by co‐expressing CYP2C19 and NADPH‐CYP oxidoreductase (OxR) proteins in Escherichia coli (E. coli) cells. In addition to RP‐HPLC, the expressed proteins were evaluated by immunoblotting and reduced CO difference spectral scanning. The RP‐HPLC assay showed good linearity (r² = 1.00) with 4‐hydroxymephenytoin concentration from 0.100 to 50.0 μm and the limit of detection was 5.00 × 10^?2 μm . Intraday and interday precisions determined were from 1.90 to 8.19% and from 2.20 to 14.9%, respectively. Recovery and accuracy of the assay were from 83.5 to 85.8% and from 95.0 to 105%. Enzyme kinetic parameters (K_m, V_max and K_i) were comparable to reported values. The presence of CYP2C19 in bacterial membranes was confirmed by immunoblotting and the characteristic absorbance peak at 450 nm was determined in the reduced CO difference spectral assay. Moreover, the activity level of co‐expressed OxR was found to be comparable to that of the literature. As a conclusion, the procedures described here have generated catalytically active CYP2C19 and the RP‐HPLC assay developed is able to serve as CYP2C19 activity marker for pharmacokinetic drug interaction study in vitro. Copyright © 2013 John Wiley & Sons, Ltd.     

The catalytic reduction of nitrobenzene at the [MoVIO2(O2CC(S)(C6H5)2)2]2− complex intercalated in a Zn(II)–Al(III) layered double hydroxide host: A kinetic model for the molybdenum–pterin binding site in nitrate reductase

The heterogeneous reduction of nitrobenzene by thiophenol catalyzed by the dianionic bis(2‐sulfanyl‐2,2‐diphenylethanoxycarbonyl) dioxomolybdate(VI) complex, [Mo^VIO₂(O₂CC(S)(C₆H₅)₂)₂]²⁻, intercalated into a Zn(II)–Al(III) layered double hydroxide host [Zn_3−xAl_x(OH)₆]^x+, has been investigated under anaerobic conditions. Aniline was found to be the only product formed through a reaction consuming six moles of thiophenol for each mol of aniline produced. The kinetics of the system have been analyzed in detail. In excess of thiophenol, all reactions follow first‐order kinetics (ln([PhNO₂]/[PhNO₂]₀) = −k_appt) with the apparent rate constant k_app being a complex function of both initial nitrobenzene and thiophenol concentrations, as well as linearly dependent on the amount of solid catalyst used. A mechanism for this catalytic reaction consistent with the kinetic experiments as well as the observed properties of the intercalated molybdenum complex has thiophenol inducing the initial coupled proton–electron transfer steps to form an intercalated Mo^IV species, which is oxidized back to the parent Mo^VI complex by nitrobenzene via a two‐electron oxygen atom transfer reaction that yields nitrosobenzene. This mechanism is widespread in enzymatic catalysis and in model chemical reactions. The intermediate nitrosobenzene thus formed is reduced directly by excess thiophenol to aniline. The values of rate coefficients indicate that reduction of nitrobenzene proceeds much faster than proton‐assisted oxidation of thiophenol. This may account for the observation that the presence of protonic amberlite IR‐120(H) increases considerably the rate of the overall reaction catalyzed. Activation parameters in excess of the protonic resin and PhSH were ΔH^≠ = 80 kJ mol⁻¹ and ΔS^≠ = −70 J mol⁻¹ K⁻¹. The large negative activation entropy is consistent with an associative transition state. The present system is characterized by a well‐defined catalytic cycle with multiple‐turnovers reductions of nitrobenzene to aniline without appreciable deactivation. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 212–224, 2001     

Synthesis,Structure, and Fluorescent Properties of Lanthanide Complexes Based on 8‐Hydroxyquinoline‐7‐carboxylic Acid

The lanthanide complex [Eu₃(8‐HQCA)₃(COOH)(OH)₂(H₂O)₃]_n · nH₂O (8‐HQCA = 8‐hydroxyquinoline‐7‐carboxylic acid) was synthesized and characterized. Single‐crystal X‐ray diffraction shows that the trinuclear structures are linked by ligands to form 2D layers. The results of DFT calculation shows that energy can be transferred effectively from the ligand to Eu^III ions. A series of heteronuclear complexes {[(Eu_1–xY_x)₃(8‐HQCA)₃(COOH) (OH)₂(H₂O)₃]_n · nH₂O (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8)} were synthesized and their luminescent properties were studied. The results showed that the doping of Y^III ions could change the fluorescent intensity of the Eu^III complex, but could not change their positions.     

Dioxygen Activation by Non‐Adiabatic Oxidative Addition to a Single Metal Center

A chromium(I) dinitrogen complex reacts rapidly with O₂ to form the mononuclear dioxo complex [Tp^tBu,MeCr^V(O)₂] (Tp^tBu,Me=hydrotris(3‐tert‐butyl‐5‐methylpyrazolyl)borate), whereas the analogous reaction with sulfur stops at the persulfido complex [Tp^tBu,MeCr^III(S₂)]. The transformation of the putative peroxo intermediate [Tp^tBu,MeCr^III(O₂)] (S=³/₂) into [Tp^tBu,MeCr^V(O)₂] (S=¹/₂) is spin‐forbidden. The minimum‐energy crossing point for the two potential energy surfaces has been identified. Although the dinuclear complex [(Tp^tBu,MeCr)₂(μ‐O)₂] exists, mechanistic experiments suggest that O₂ activation occurs on a single metal center, by an oxidative addition on the quartet surface followed by crossover to the doublet surface.     

Synthesis,spectroscopic, thermal and biological aspects of drug‐based copper(II) complexes

A series of novel complexes of the type Cu(II)(L_n)₂(H₂O)₂]^•xH₂O [where L_n = L _1–4 , these ligands being described as: L ₁ , 2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)phenol, x = 1; L ₂ , 2‐({4‐[6,7‐dihydrothieno[3,2‐c] pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)‐5‐(methoxy)phenol, x = 2; L ₃ , 5‐chloro‐2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)phenol, x = 2; and L ₄ , 5‐bromo‐4‐chloro‐2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino} methyl)phenol, x = 1] was investigated. They were characterized by elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR and electronic spectra, magnetic measurements and thermal studies. The FAB‐mass spectrum of [Cu(II)( L ₁ )₂(H₂O)₂]^•H₂O was determined. A magnetic moment and reflectance spectral study revealed that an octahedral geometry could be assigned to all the prepared complexes. Ligands (L_n) and their metal complexes were screened for their in vitro antibacterial activity against Bacillus subtillis, Pseudomonas aeruginosa, Escherichia coli and Serratia marcescens bacterial strains. Kinetic parameters such as order of reaction (n), the energy of activation (E_a), the pre‐exponential factor (A), the activation entropy (ΔS^≠), the activation enthalpy (ΔH^≠) and the free energy of activation (ΔG^≠) are reported. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and Chloride Affinity of Sterically Demanding Ditopic Lithium Bis(pyrazol‐1‐yl)borates

The synthesis and full characterization of the sterically demanding ditopic lithium bis(pyrazol‐1‐yl)borates Li₂[p‐C₆H₄(B(Ph)pz^R₂)₂] is reported (pz^R = 3‐phenylpyrazol‐1‐yl ( 3 ^Ph), 3‐t‐butylpyrazol‐1‐yl ( 3 ^tBu)). Compound 3 ^Ph crystallizes from THF as THF‐adduct 3 ^Ph(THF)₄ which features a straight conformation with a long Li···Li distance of 12.68(1) Å. Compound 3 ^tBu was found to function as efficient and selective scavenger of chloride ions. In the presence of LiCl it forms anionic complexes [ 3 ^tBuCl]⁻ with a central Li‐Cl‐Li core (Li···Li = 3.75(1) Å).     

Synthesis and Crystal Structures of t‐Butyl‐Pyridine Adducts of ZnR2 (R = Me,i‐Pr,t‐Bu,Cp*)

Lewis acid‐base adducts of the general type R₂Zn(4‐tBuPy)_x (R = Me 1 , iPr 2 , tBu 3 , Cp* 4 ; x = 1, 2) were obtained in high yields from reactions of ZnR₂ with the Lewis base 4‐tBu‐Pyridine. Compounds 1 – 4 were characterized by multinuclear NMR (¹H, ¹³C) and IR spectroscopy and elemental analyses, 1 and 4 also by X‐ray diffraction at single crystals.