Crystal structure of 3,3-dichloro-N-p-methoxyphenyl-4-(2-phenylstryl)-2-azetidinone.

3,3-Dichloro-N-p-methoxyphenyl-4-(2-phenylstryl)-2-azetidinone (C22H15Cl2NO2) was studied by X-Ray analysis, which indicated a monoclinic space group, P2(1)/c, with a = 9.619(5), b = 13.879(4), c = 14.161(5)A, beta = 100.16(3)degrees, V = 1860.8(13)A3, Z = 4, Dc = 1.414 g cm(-3), micro(Mo Kalpha) = 0.366 mm(-1) and F000 = 816. The structure was solved by direct methods and refined to R = 0.041 for 4026 reflections [I > 2sigma(I). The beta-lactam ring (2-azetidinone) has antimicrobial affects. The substituents of the methoxyphenyl and phenyl substituents do not change the activity property of the beta-lactam ring, and the activity properties depend on the planarity of the beta-lactam ring.     

Two New Insecticidal Amide Dimers from Fruits of Piper nigrum Linn.

The methanolic extract of dried ground seeds of Piper nigrum Linn . afforded fourteen compounds, of which thirteen were amides, including two new isomeric insecticidal amides, pipsaeedine ( 1 ) and pipbinine ( 2 ), along with eleven known amides and piptaline; (this is the first report of isolation of these compounds from this plant). The structures of 1 and 2 have been elucidated as (E,E)‐1‐[(E)‐5‐(7‐{6‐[5‐(piperidin‐1‐yl)‐5‐oxopent‐3‐enyl]‐1,3‐benzodioxol‐4‐yl}‐1,3‐benzodioxol‐5‐yl)‐1‐oxopenta‐2,4‐dienyl]piperidine and (E,E)‐1‐[(E)‐5‐(4‐{6‐[5(piperidin‐1‐yl)‐5‐oxopent‐3‐enyl]‐1,3‐benzodioxol‐4‐yl}‐1,3‐benzodioxol‐5‐yl)‐1‐oxopenta‐2,4‐dienyl]piperidine, respectively, through extensive 1D‐ and 2D‐NMR spectral studies, while the known constituents have been identified through comparison of their spectral data with those reported in the literature. Compounds 1 and 2 exhibited toxicities of 45.0 and 40.0 ppm, respectively, against fourth instar larvae of Aedes aegypti Liston.     

Heating of cold cesium atoms by blue-detuned laser radiation

Received: 12 March 1997/Revised version: 30 July 1997     

New anthraquinones from the stem of Morinda citrifolia Linn

Studies on the chemical constituents of the stem of Morinda citrifolia, Linn. have led to the isolation of two new compounds, morindicinone (=2-hydroxy-1,8-dimethoxy-7-methoxymethylanthraquinone, 1) and morindicininone (=4-hydroxymethyl-1,3-dimethoxyanthraquinone, 2), as well as two known constituents, 2-hydroxyanthraquinone (3) and 2-methoxyanthraquinone (4). Their structures were elucidated by spectral analysis including 2D-NMR techniques.     

Tuning excited-state electron transfer from an adiabatic to nonadiabatic type in donor-bridge-acceptor systems and the associated energy-transfer process

Through design and synthesis of a new series of dyads I-III composed of 2,3-dimethoxynaphthalene as an electron donor (D) and 2,3-dicyanonaphthalene as an acceptor (A) bridged by n-norbornadiene (n = 1-3) we demonstrate an excellent prototype to switch the excited-state electron-transfer dynamics from an adiabatic to a nonadiabatic process. I reveals a remarkable excitonic effect and undergoes an adiabatic type of electron transfer (ET), resulting in a unique charge-transfer emission, of which the peak wavelength exhibits strong solvatochromism. Conversely, upon exciting the donor moiety, a fast D --> A energy transfer takes place for II (approximately 3 ps) and III (< or =30 ps), followed by a nonadiabatic type, weak coupled electron transfer with a relatively slow ET rate, giving rise to dual emission in polar solvents. Further detailed temperature-dependent studies of the ET rate deduced reaction barriers of 2.7 kcal/mol (for II) and 1.3 kcal/mol (for III) in diethyl ether and CH2Cl2, respectively. The results lead to a deduction of the reaction free energy and reorganization energy for both II (in diethyl ether) and III (in CH2Cl2). Theoretical (for I) and experimental (for II and III) approaches estimate the electronic coupling to be 860, 21.9, and 3.2 cm(-1) for I, II, and III, respectively, supporting the adiabatic versus nonadiabatic switching mechanism.     

Changes in the Inter- and Intra- Fibrillar Structure of Lyocell (TENCEL®) Fibers after KOH Treatment

Lyocell fibers were treated with KOH up to 8 M which was demonstrated to distribute homogeneously at the outer zones of fiber cross section compared to NaOH which accesses more deeply but less homogenously. Both NaOH and KOH solutions can be used to lower significantly the fibrillation of lyocell fibers. However, due to intrafibrillar swelling together with deep penetration ability of alkali seen for NaOH treatments results in great fiber tensile strength loss which is not observed for KOH treatments due to its inability to penetrate the fiber completely. The porous structure of fibers was studied by inverse size exclusion chromatography (ISEC) to identify mean pore diameter, total pore area and accessible pore volume (APV). Mean pore diameter of fibers decreased after KOH treatments which did not change after NaOH treatments. Wide angle X-ray diffraction analyses (WAXD) were applied to identify the crystallinity index and crystallite size. In general, fiber properties such as water retention value, carboxyl content using methylene blue sorption method, depth of color measured after dyeing with C.I. Direct Red 81 and weight loss were distinctly different in the ranges up to 2 M, 2-5 M and 5 to 8 M KOH. KOH treatment suggests new possibilities for the pretreatment of lyocell fibers to lower fibrillation while slightly lowering elongation at break without a distinct loss in tensile strength and with less decrease in carboxyl content and weight loss without changing dyeing properties of fibers compared to NaOH treatment.     

Radiolabeled Nanogels for Nuclear Molecular Imaging

An efficient and simple synthesis approach to form stable ⁶⁸Ga‐labeled nanogels is reported and their fundamental properties investigated. Nanogels are obtained by self‐assembly of amphiphilic statistical prepolymers derivatised with chelating groups for radiometals. The resulting nanogels exhibit a well‐defined spherical shape with a diameter of 290 ± 50 nm. The radionuclide ⁶⁸Ga is chelated in high radiochemical yields in an aqueous medium at room temperature. The phagocytosis assay demonstrates a highly increased internalization of nanogels by activated macrophages. Access to these ⁶⁸Ga‐nanogels will allow the investigation of general behavior and clearance pathways of nanogels in vivo by nuclear molecular imaging.

     

Bound states of the Dirac equation with position-dependent mass for the Eckart potential

Studying with the asymptotic iteration method, we present approximate solutions of the Dirac equation for the Eckart potential in the case of position-dependent mass. The centrifugal term is approximated by an exponential form, and the relativistic energy spectrum and the normalized eigenfunctions are obtained explicitly.     

Reactions of Substituted Indoles with 2,3-Dichloro-1,4-naphthoquinone and Electrochemical Properties of Some 2,3-Substituted 1,4-Naphthoquinones

Russian Journal of Organic Chemistry - The reactions of 2,3-dichloro-1,4-naphthoquinone with some indoles and thiols were investigated. The resulting nucleophilic substitution products were...