H,C, Pt NMR study on platinum(II) interaction with sulphur containing Amadori compounds

The NMR study on the interaction of Pt(II) with Amadori compounds is performed. The Amadori compounds are derived from the reaction of β-d-glucose with l-cystine leading to N,N′-di-(1-deoxy-β-fructos-1-yl)-l-cystine [FruCyscys], and with l-methionine leading to N-(1-deoxy-β-fructos-1-yl)-l-methionine [FruMet].     

Fluorescence-dip infrared spectroscopy and predissociation dynamics of OH A 2Sigma+ (v = 4) radicals

Fluorescence-dip infrared spectroscopy, an UV-IR double-resonance technique, is employed to characterize the line positions, linewidths, and corresponding lifetimes of highly predissociative rovibrational levels of the excited A (2)Sigma(+) electronic state of the OH radical. Various lines of the 4 <--2 overtone transition in the excited A (2)Sigma(+) state are observed, from which the rotational, centrifugal distortion, and spin-rotation constants for the A (2)Sigma(+) (v = 4) state are determined, along with the vibrational frequency for the overtone transition. Homogeneous linewidths of 0.23-0.31 cm(-1) full width at half maximum are extracted from the line profiles, demonstrating that the N = 0 to 7 rotational levels of the OH A (2)Sigma(+) (v = 4) state undergo rapid predissociation with lifetimes of < or =23 ps. The experimental linewidths are in near quantitative agreement with first-principles theoretical predictions.     

Synthesis of alkyl α‐aminomethyl‐phenylphosphinates and N,N‐bis(alkoxyphenylphosphinylmethyl)amines by the microwave‐assisted Kabachnik–Fields reaction

As a novel extension, the Kabachnik–Fields reaction was applied to the synthesis of alkyl α‐aminomethyl‐phenylphosphinates, and the double phospha‐Mannich reaction was utilized in the preparation of bis(alkoxyphenylphosphinylmethyl)amines. A total of 27 new aminophosphinate derivatives were synthesized by the microwave‐assisted solvent‐free condensation of alkyl phenyl‐H‐phosphinates, paraformaldehyde, and primary or secondary amines. The starting P‐species were also prepared under microwave conditions. The formation of the N‐methylated aminomethyl‐phenylphosphinate by‐products was also investigated.     

Measuring the solubilities of ionic liquids in water using ion-selective electrodes

Polyvinyl chloride-plasticized membrane ion-selective electrodes (ISE) based on conventional ion-exchangers have been proposed as a cheap universal tool to measure the solubilities of ionic liquids (ILs) in water. They are applicable for ILs with a wide range of solubilities in water, since the linear range of a potentiometric response spans several orders of magnitude. As an example, we have fabricated and tested ISEs for widely used alkylimidazolium ionic liquids. The aqueous solubilities of four typical ILs have been determined at 21 °C: 0.075±0.001 mol l^–1 (1-butyl-3-methylimidazolium, BMIm, hexafluorophosphate); 0.018±0.001 mol l^–1 (BMIm bis(triflylimide)); 0.054±0.007 mol l^–1 (1-butyl-2,3-dimethylimidazolium, BDMIm, hexafluorophosphate); 0.014±0.001 mol l^–1 (BDMIm bis(triflylimide)).     

Enhanced relaxation of nanoparticle-bound supercoiled DNA in X-ray radiation

A therapeutic methodology was developed based on the large X-ray absorption cross-section of gold nanoparticles at high photon energies (>81 keV). Experimental results showed that the amounts of the relaxed circular supercoiled DNA (scDNA) for gold nanoparticle-bound scDNA were more than doubled compared to that for free scDNA under otherwise identical radiation conditions.     

Conformational effects on the performance and selectivity of a polymeric pseudostationary phase in electrokinetic chromatography

The effect of the conformation of a polymeric pseudostationary phase on performance and selectivity in electrokinetic chromatography was studied using an amphiphilic pH-responsive polymer that forms compact intramolecular aggregates (unimer micelles) at low pH and a more open conformation at high pH. The change in conformation was found to affect the electrophoretic mobility, retention, selectivity, and separation efficiency. The low-pH conformer has higher electrophoretic mobility and greater affinity for most solutes. The unimer micelle conformation was also found to provide a solvation environment more like that of micelles and other amphiphilic self-associative polymers studied previously. It was not possible to fully characterize the effect of conformation on efficiency, but very hydrophobic solutes with long alkyl chains appeared to migrate with better efficiency when the unimer micelle conformation was employed. The results imply that polymers with a carefully optimized lipophilic-hydrophilic balance that allow self-association will perform better as pseudostationary phases. In addition, the results show that electrokinetic chromatography is a useful method for determining the changes in solvation environment provided by stimuli-responsive polymers with changes in the conditions.     

Syntheses of dictyopterene B (hormosirene) and its enantiomer via asymmetric ScN′ reactions

Stereocontrolled syntheses of dictyopterene B (hormosirene) (1) and its enantiomer (ent-1) are reported. Key steps are highly stereoselective S_cN′ reactions of esters of alcohols 2 and 5 derived from (+)-camphor.     

Mass spectrometric approaches for elucidation of antigenantibody recognition structures in molecular immunology

Mass spectrometric approaches have recently gained increasing access to molecular immunology and several methods have been developed that enable detailed chemical structure identification of antigen-antibody interactions. Selective proteolytic digestion and MS-peptide mapping (epitope excision) has been successfully employed for epitope identification of protein antigens. In addition, "affinity proteomics" using partial epitope excision has been developed as an approach with unprecedented selectivity for direct protein identification from biological material. The potential of these methods is illustrated by the elucidation of a beta-amyloid plaque-specific epitope recognized by therapeutic antibodies from transgenic mouse models of Alzheimer's disease. Using an immobilized antigen and antibody-proteolytic digestion and analysis by high resolution Fourier transform ion cyclotron resonance mass spectrometry has lead to a new approach for the identification of antibody paratope structures (paratope-excision; "parex-prot"). In this method, high resolution MS-peptide data at the low ppm level are required for direct identification of paratopes using protein databases. Mass spectrometric epitope mapping and determination of "molecular antibody-recognition signatures" offer high potential, especially for the development of new molecular diagnostics and the evaluation of new vaccine lead structures.     

Infrared action spectroscopy and dissociation dynamics of the HOOO radical

The HOOO radical has long been postulated to be an important intermediate in atmospherically relevant reactions and was recently deemed a significant sink for OH radicals in the tropopause region. In the present experiments, HOOO radicals are generated in a pulsed supersonic expansion by the association of O(2) and photolytically generated OH radicals, and the spectral signature and vibrational predissociation dynamics are investigated via IR action spectroscopy, an IR-UV double resonance technique. Rotationally resolved IR action spectra are obtained for trans-HOOO in the fundamental (nu(OH)) and overtone (2nu(OH)) OH stretching regions at 3569.30 and 6974.18 cm(-1), respectively. The IR spectra exhibit homogeneous line broadening, characteristic of a approximately 26-ps lifetime, which is attributed to intramolecular vibrational redistribution and/or predissociation to OH and O2 products. In addition, an unstructured feature is observed in both the OH fundamental and overtone regions of HOOO, which is likely due to cis-HOOO. The nascent OH X(2)Pi, v = 0 or v = 1, products following vibrational predissociation of HOOO, nu(OH) or 2nu(OH), respectively, have been investigated using saturated laser-induced fluorescence measurements. A distinct preference for population of Pi(A') Lambda-doublets in OH was observed and is indicative of a planar dissociation of trans-HOOO in which the symmetry of the bonding orbital is maintained.     

Design of a novel G-quenched molecular beacon: a simple and efficient strategy for DNA sequence analysis

G-quenched MBs are devised from readily available starting materials and used for sequence specific DNA detection with high efficiency.