Coinage Metal Complexes with Di-tertiary-butyl Sulfide as Precursors with Ultra-Low Decomposition Temperature

We report here the synthesis of [Cu₂(TFA)₄(^tBu₂S)₂] ( 1 ), [Ag₄(TFA)₄(^tBu₂S)₄] ( 2 ) and [AuCl(^tBu₂S)] ( 3 ) (TFA=trifluoroacetate), which decompose in solution medium at ultra-low temperature (e. g., in boiling toluene) to afford phase-pure and highly crystalline Cu₉S₅, Ag₂S and metallic Au nanoparticles, respectively. The low decomposition temperature of these precursors is attributed to the facile decomposition mechanism in the di-tertiary-butyl sulfide ligand. These results are a significant step in the direction of establishing a general low-temperature strategy spanning a range of systems including thermodynamically metastable materials and incorporate them in technologies that are sensitive to the harsh conditions.     

Measurement of the Dynamic Bulk and Shear Response of Soft Human Tissues

Traditionally, Kolsky bars are used to study the dynamic response of hard materials in uniaxial compression, tension or torsion. We present modifications to the technique that allow loading of a soft tissue specimen in (a) hydrostatic compression and (b) simple shear. The first modification is designed to determine the pressure vs. volume behavior of each material, and thence to extract a measure of the dynamic compressibility or equivalently of the bulk modulus. The second modification is designed to develop the shear stress versus shear strain behavior for a near-simple shear experiment. The critically important questions of the proper acquisition of human tissue samples and protocols for appropriate experimentation have also been addressed. The experimental techniques and the results are discussed in detail and the results compared to finite element simulations. We present examples of the dynamic response of typical tissue simulants as well as human liver and stomach tissues.     

Rarefied gas flows based on variational principle

A variational principle has been utilized to study Couette flow, and Kramers' velocity slip problem with specular-diffuse reflection. The method leads to extremely satisfactory analytic results for the velocity slip coefficient and also for the variation of shear stress with inverse Knudsen number. This leads us to the conclusion that the present variational principle even with extremely simple trial functions, essentially suggested by continuum flow theory, is a useful means of computing macroscopic quantities of physical interest in rarefied gas dynamics.     

Spray desorption collection: an alternative to swabbing for pharmaceutical cleaning validation

Spray Desorption Collection (SDC) allows for much larger areas of surfaces to be sampled compared to traditional swabbing techniques, providing a valuable pre-concentration advantage. Closely related to desorption electrospray ionization (DESI), analytes from the sample surface are collected onto a selected collection surface, which in a second step can be analyzed directly. Here we demonstrate the application of SDC as a large surface area sampling tool coupled with paper spray MS (PS-MS) and demonstrate its capabilities for cleaning validation of pharmaceutical equipment for both acidic and basic active ingredients from an aluminium surface.     

Fabrication and Properties of Redox Ion Doped Few Monolayer Thick Polyelectrolyte Film for Electrochemical Biosensors at High Sensitivity and Specificity

Redox ions are deposited on a polyelectrolyte‐coated gold electrode by an electric field to fabricate an ion‐selective thin film electrode. The Fe(CN)${{{4- \hfill \atop 6\hfill}}}$ ions are deposited on a few monolayer‐coated polyelectrolyte gold electrode by a slow periodic potential cycle. The deposition process and electrode properties are quantitatively and simultaneously monitored by cyclic voltammetry and a novel technique, using a Scanning Electrometer for Electrical Double‐layers (SEED). No redox properties are obtained without the electric‐field‐deposition. Owing to the redox mediation and net charge due to the redox ion, the electrode is ion‐selective. We demonstrate the principle to detect 1 µM of dopamine in a mixture with 1 mM of ascorbic acid.     

Synthesis of thiazole clubbed pyrazole derivatives as apoptosis inducers and anti-infective agents

Fourteen N-[{(substituted-phenylthiazol-2-yl)-3-aryl-1H-pyrazol-4-yl}methylene]-5-substituted-thiazol-2-amine (5a-n) analogs were synthesized by the reaction of 3-aryl-1-(thiazol-2-yl)-1H-pyrazole-4-carbaldehyde and substituted thiazole amines. The structures of prepared compounds were delineated by elemental analysis, FT-IR and ¹H NMR spectra. These analogs were scrutinized for in vitro anti-infective and cytotoxic activities. Some thaizole clubbed pyrazole derivatives were assessed for their cytological changes in germ cells of Capra hircus by using histomorphological analysis, fluorescence assay and apoptosis quantification. Compound 5l having 4-NO₂ substituent induced the significant apoptosis in tested cells of Capra hircus. The results revealed that compounds 5c, 5e, 5k, and 5l have commendable antibacterial activity within MIC range of 62.5–250 μg/ml. Compound 5c emerged as a potent antimalarial compound by exhibiting IC₅₀ value of 0.23 μg/ml and compound 5j induced paralysis of Pherentima posthuma at 8.6 ± 1.94 min and death at 20 ± 5.04 min, respectively. Compound 5j revealed an excellent cytotoxicity at IC₅₀ value of 30.7 and < 10 μg/ml against MCF-7 and HeLa cells, respectively. Individually, compounds 5c, 5j and 5l could be considered as promising anti-infective and cytotoxic compounds.     

Binding of 8-anilino-1-naphthalenesulfonate to lecithin:cholesterol acyltransferase studied by fluorescence techniques

The solvatochromic fluorescent probe 8-anilino-1-naphthalenesulfonate (ANS) has been used to study the hydrophobicity and conformational dynamics of lecithin:cholesterol acyltransferase (LCAT). The ANS to LCAT binding constant was estimated from titrations with ANS, keeping a constant concentration of LCAT (2 microM). Apparent binding constant was found to be dependent on the excitation. For the direct excitation of ANS at 375 nm the binding constant was 4.7 microM(-1) and for UV excitation at 295 nm was 3.2 microM(-1). In the later case, not only ANS but also tryptophan (Trp) residues of LCAT is being excited. Fluorescence spectra and intensity decays show an efficient energy transfer from tryptophan residues to ANS. The apparent distance from Trp donor to ANS acceptor, estimated from the changes in donor lifetime was about 3 nm and depends on the ANS concentration. Steady-state and time-resolved fluorescence emission and anisotropies have been characterized. The lifetime of ANS bound to LCAT was above 16 ns which is characteristic for it being in a hydrophobic environment. The ANS labeled LCAT fluorescence anisotropy decay revealed the correlation time of 42 ns with a weak residual motion of 2.8 ns. These characteristics of ANS labeled LCAT fluorescence show that ANS is an excellent probe to study conformational changes of LCAT protein and its interactions with other macromolecules.     

Anhydrous scandium, yttrium, lanthanide and actinide halide complexes with neutral oxygen and nitrogen donor ligands

Studies on lanthanide and actinide halide complexes with neutral O- and/or N-donor ligands have intensified in recent years due to their implications in homogeneous catalysis, magnetic and optical materials, as synthons for the synthesis of novel coordination and organometallic compounds and, for Ln(II) halide complexes, as reducing agents in organic synthesis. Synthetic strategies, structural diversity as well as some important properties and reactivities of these anhydrous metal (including scandium and yttrium) halide complexes are reviewed here. These complexes also hold potential as starting materials for constructing more sophisticated heterometallic assemblies by crystal engineering; the compounds of this class, either discrete ion-pairs or coordination polymers, being discussed separately under the heading heterometallic lanthanide and actinide halide complexes. The aim of this article is to provide a reference text for the researchers working in the lanthanide and actinide coordination chemistry field and to identify and signify the area of future research.     

Redistribution reactions of heteroleptic barium iodide derivatives: Synthesis and structures of trans-BaI2(DME)(triglyme), cis-BaI2(DME)(tetraglyme) and [Ba(tetraglyme)2]I2 · C7H8

The reaction between BaI₂ · 2H₂O and NaHFIP [HFIP = OCH(CF₃)₂] in a 1:1 stoichiometry gave the heterometallic compound NaBaI₂(HFIP)(H₂O)(THF)_0.5 (1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI₂(DME)₃ (2), trans-BaI₂(DME)(triglyme) (3) and cis-BaI₂(DME)(tetraglyme) (4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI₂ · 2H₂O and NaTFA (TFA = O₂CCF₃) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)₂]I₂ · C₇H₈ (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and ¹H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 Å for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 Å for 4.