Synthesis,crystal structure,and photoluminescence of zinc complex [Zn(Qina)<Subscript>2</Subscript>(DMSO)<Subscript>2</Subscript>] · 2DMSO

A novel complex [Zn(Qina)₂(DMSO)₂] · 2DMSO (I) (Qina = quinaldic acid, DMSO = dimethyl sulfoxide) has been synthesized and characterized by X-ray diffraction, elementary analysis, and IR spectrum. The unit cell parameters for complex I: a = 8.2884(11), b = 22.015(3), c = 9.0685(12) Å, β = 100.61(0)°, V = 1626.41(40) ų, Z = 2, space group, P2₁/n. In the complex I, the Zn(II) atom was six-coordinated to form a distorted octahedral geometry by two Qina ligands and two dimethyl sulfoxide molecules. The crystal structure is stabilized by hydrogen bonds, C - H... π, π-π stacking interaction between adjacent complexes. The binding of the complex I with calf thymus DNA has been investigated by fluorescence spectroscopic studies. The result suggested that the complex intercalates into DNA base pairs.     

Bioelectrochemical response of a choline biosensor fabricated by using polyaniline

On the basis of the isoelectric point of an enzyme and the doping principle of conducting polymers, choline oxidase was doped in a polyaniline film to form a biosensor. The amperometric detection of choline is based on the oxidation of the H₂O₂ enzymatically produced on the choline biosensor. The response current of the biosensor as a function of temperature was determined from 3 to 40°C. An apparent activation energy of 22.8 kJ·mol⁻¹ was obtained. The biosensor had a wide linear response range from 5 × 10⁻⁷ to 1 × 10⁻⁴ M choline with a correlation coefficient of 0.9999 and a detection limit of 0.2 μM, and had a high sensitivity of 61.9 mA·M⁻¹·cm⁻² at 0.50 V and at pH 8.0. The apparent Michaelis constant and the optimum pH for the immobilized enzyme are 1.4 mM choline and 8.4, respectively, which are very close to those of choline oxidase in solution. The effect of selected organic compounds on the response of the choline biosensor was studied.     

Potential-modulated fluorescence spectroscopy of the membrane potential-sensitive dye di-4-ANEPPS at the 1,2-dichloroethane/water interface

The spectrofluorometric behavior of a membrane potential-sensitive dye, 1-(3-sulfonatopropyl)-4-[β-{2-(di-N-butylamino)-6-naphthyl}vinyl]pyridinium betaine (di-4-ANEPPS), at the polarized 1,2-dichloroethane/water interface was studied by means of potential-modulated fluorescence (PMF) spectroscopy. The results, combined with those from cyclic and alternating current voltammetry, clearly suggested that the dye adsorbed at the interface underwent a reorientation with increasing the interfacial potential, giving a well-developed PMF response as well as a voltammetric response. In addition to the PMF response, another PMF response was observed by addition of dilauroyl phosphatidylcholine (DLPC). This additional response was well explained in terms of a reorientation of di-4-ANEPPS at the interface, which would be induced by the potential-dependent desorption of DLPC from the interface. Thus, the present study supported the reorientation/solvatochromic mechanism for the membrane potential-sensitive dye rather than the electrochromic mechanism.     

Cyloadditions of benzopyrones: Rapid access to bicyclic AB-ring analogues of anthracyclines

Cycloaddition of the benzopyrone 10b with 1,1-disubstituted alkenes 12, 14, and 16 produces fair yields of the lactones 13, 15, and 17, AB-ring analogues of the anthracyclines.     

Regiospecific synthesis of mono- and bicyclic 6-alkoxy-2-pyrones and their use in the preparation of substituted aromatics,anthraquinones, and tetracyclic intermediates for 11-deoxyanthracycline synthesis

Several mono- and bicyclic 6-methoxy-2-pyrones having substituents at C4 and C5 can be prepared regiospecifically by either of two routes: (1) regiospecific construction of a glutaconic half-ester followed by dehydrative cyclization, and (2)regiospecific Friedel-Crafts acylation of 6-methoxy-2-pyrones at C5. These pyrones undergo clean and regiospecific Diels-Alder cycloadditions with various unsymmetrical dienophiles, e.g., quinones, unsaturated esters, etc, with subsequent loss of carbon dioxide. In this manner several polycyclic aromatic natural products have been prepared such as chrysophanol, helminthosporin, pachybasin, 2-acetylemodin and the purported structure for orientalone. The utility of this approach for the synthesis of the anthracyclines is demonstrated by its use in the preparation of various tetracyclic intermediates for anthracycline synthesis.     

Determination of Trace Molybdenum in Biological Matrices by Neutron Activation Analysis

Based on consecutive extractions using bismuth diethyldithiocarbamate and thallium diethyldithiocarbamate as reagents, molybdenum was selectively and highly enriched from biological matrices, and then subjected to neutron activation analysis. Most of interfering elements, e.g., Na, K, Br, P, Fe, U, etc. were simultaneouly removed and the preconcentrated samples always showed only the r rays from molybdenum after neutron bombardment. Thus, molybdenum in the biological matrices could be accurately determined.     

Photochemistry of 2-Allyl-3-oxo-2,3-dihydro-1H-pyrrole-2-carboxyalates

On acetone-sensitized irradiation the title compounds 3a–c are converted to 2-allyl-3-hydroxy-1H-pyrrole-2-carboxylates 4 in reasonable yields.     

Three-dimensional display by use of integral photography with dynamically variable image planes

A computer-generated integral photography system operating with a variable image plane is proposed. In this scheme, the gap between a lens array and a display panel is adjusted in real time. A synchronized elemental image array for real or virtual mode is integrated in front of or behind the lens array. This integration gives an observer an enhanced perception of depth. The proposed method can be applied to animated three-dimensional imaging.