Structure and absolute configuration of enhydrin bromohydrin

X-ray study of enhydrin bromohydrin, C₂₃H₂₉BrO₁₀, reveals that the crystal has space groupP2₁2₁2₁ with cell parametersa =10.08,b = 26.97, andc = 8.94 Å. There are four molecules in the unit cell. The structure was solved by direct methods, with three-dimensional CuK diffractometer data to = 75 °, and refined by block-diagonal least squares to anR index of 11.4% for 2254 reflections. The molecule is a germacronolide sesquiterpene having acis sterochemistry at the C(1), C(10) double bond and atrans configuration at the epoxide ring, C(4)-O-C(5). The absolute configuration established on the basis of the anomalous scattering of CuK. radiation by the bromine atom shows that the asymmetric atoms have the 4R, 5R, 6S, 7S, 8S, 9S, 20S, and 22S configurations.     

Synthesis of quaternary succinimides promoted by Ferric Nitrate

An efficient protocol has been accomplished for the synthesis of quaternary α-aminosuccinimides in toluene medium involving 2-phenylimidazo[1, 2-a]pyridine in a one-pot reaction promoted by Ferric Nitrate at 120?°C. The protocol presented herein, is for the first time, via a novel transformation where Ferric Nitrate promotes imidazo[1,2-a]pyridine structural metamorphosis to the title compound quaternary succinimides. High compatibility, easy work-up, and excellent yields are the advantages of this protocol. The quaternary α-aminosuccinimides are expected to have great potential in synthesizing quaternary α-amino acids and applications in medicinal chemistry.     

A novel conjugated polymer containing alternating p‐ and n‐type moieties with balanced properties of conducting holes and electrons

A new electroluminescent conjugated polymer consisting of 2,2′‐bipyridylenevinylene (BPyV) and 2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene (MEH‐PV) moieties (BPy‐MEH‐PPV), was synthesized by incorporating an n‐dope type moiety, BPyV, and a p‐dope type moiety, MEH‐PV, into the polymer chain. This facile method provides a new approach to the synthesis of conjugated polymers with balanced ability of conducting electrons and holes. PBy‐MEH‐PPV exhibits tunable optical properties through protonation, and the emissive color can be progressively changed from orange to deep red depending on the degree of protonation.     

The Structure of Generalized Lorenz-Mie Theory for Elliptical Infinite Cylinders

Generalized Lorenz-Mie theory (GLMT) for elliptical cylinders is concisely described. Rather than insisting on technicalities which will appear elsewhere, this paper provides a guide allowing one to gain a bird view over the structure of the theory. As a by-product, the structure of the GLMT for circular cylinders is revisited.     

Sonophysically‐Exfoliated Individual Multi‐Walled Carbon Nanotubes in Water Solution

We report the sonophysically‐exfoliated methods access to the preparation of homogeneous‐free multi‐walled carbon nanotubes (MWCNTs) in water solution. Highly stable, uniform, individual MWCNTs are entirely performed through sodium dodecylsulfate surfactants by means of a tip sinicator. HRTEM images show that the crystalline finger walls of individual CNTs are apparently observed. Raman spectrum of MWCNTs shows that the so‐called G'‐band, associated with metallic electronic structure, was significantly observed at 2644 cm^?1 with full‐width at half‐maximum of 262 cm^?1, indicating that the sonication physical methods do not alter their electric properties. Owing to its easy‐to‐use procedure and low cost of implementation, this approach could lead to the commercial viability of the large‐scale MWCNTs processing.     

Growth behavior of CuPc films by physical vapor deposition

Various Cu‐phthalocyanine (CuPc) films were grown from physical vapor deposition on top of indium‐tin‐oxide glass substrates by controlling substrate temperature (T_sub), source temperature (T_sou), and growth time. From side‐view SEM pictures, the growth rates for these CuPc films are estimated and can be categorized into three regions. From the Arrhenius plot of growth rate versus 1/T_sub, the activation energy E_A can be obtained. As T_sou = 390 °C, for region (A) with T_sub < 140 °C, the growth of CuPc films is dominated by the adhesion process with E_A = 810 meV. For region (B) with 140 °C < T_sub < 320 °C, the growth is then limited by the steric character associated with the organic molecular solids with E_A = 740 meV. For region (C) with T_sub > 320 °C, the re‐evaporation of the CuPc adhered molecules from the interface becomes dominant. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Functionalized self-assembled monolayers on ultraflat gold as platforms for single molecule force spectroscopy and imaging

Single molecule force spectroscopy is a valuable tool for studying unfolding and nanomechanical properties of proteins. The common practice is to stretch proteins from a surface that was dosed to give a reasonable hit rate and to analyze the curves that exhibit the expected characteristics of a single polymer. Whether the surface-bound proteins are indeed single and isolated remains unclear, and the undesirable protein/surface interactions that obscure informative features of the force curves are implicitly assumed to be absent. In this study, mixed self-assembled monolayers (SAMs) consisting of N-hydroxysuccinimide (NHS) and oligoethylene glycol (OEG) terminated thiols on an ultraflat gold surface were used to covalently immobilize proteins via lysine residues. By the optimization of attachment sites via lysine-NHS linkages amidst a protein-resistant layer of the OEG SAM, it was possible to isolate single proteins for study in a controlled fashion. The single protein distribution on the surface is clearly demonstrated by atomic force microscopy (AFM) imaging. The OEG also significantly reduces nonspecific tip-surface interactions between the cantilever and surface. Stretching covalently attached single proteins produces high-quality and reproducible force-extension curves. This experimental strategy is an attractive platform with which to study protein structure, interactions, and nanomechanical properties of single proteins.     

Direct adsorption and monolayer self-assembly of acetyl-protected dithiols

The alpha,omega-dithiols, with sulfur-containing groups at both ends of the molecules, can be used to bridge a metallic gap. Functional self-assembled monolayers (SAMs) of these dithiols must "stand up" on the surface and expose one thiol group for further reaction. However, both parallel and upright surface orientations and multilayer formation can occur for alpha,omega-dithiols. We find SAMs deposited directly from acetyl protected dithiols (i.e., with no de-protection step) overcome these problems. We present a systematic study of adsorption kinetics from in situ surface plasmon resonance spectroscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy of alkane- and oligo(phenylene ethylnylene)-based alpha,omega-dithioacetates on gold.     

Manipulating the retrieved frequency and polarization of stored light pulses

We have experimentally demonstrated that stored and retrieved light pulses have different frequencies but maintain phase coherence; a stored light pulse is released with a different polarization. However, the manipulation process causes an energy loss of the retrieved pulse. We have discovered that Clebsch-Gordan coefficients among the Zeeman sublevels play an important role in the energy loss and have demonstrated a solution for avoiding the energy loss.     

Simultaneous measurement of refractive index and thickness with a convergent beam

A new approach to the simultaneous measurement of refractive index and thickness based on the focus shifts of a convergent beam intercepted by a test plate is proposed. By using ray optics, a defined focus shift can be derived as a function of the refractive index and thickness as well as the angular position of the test plate with respect to the optical axis. From a pair of focus shifts obtained at two different angular positions, it is shown that the desired measurands can be simultaneously determined without prior knowledge of either parameter. A simulation result for the proposed concept based on graphically solving the equations of their respective focus shifts is presented.