Synthesis and Second‐Order Nonlinearities of Chiral Prolinol‐Substituted Chromophores

A new series of thiophene‐ and furan‐containing chromophores with a chiral prolinol donor and a sulfone acceptor has been synthesized. The UV‐vis absorptions, second‐order nonlinear optical properties, and X‐ray crystal structures are described.     

A Theoretical Investigation of the Decomposition Reactions of Ethyl Formate in the S0 State

This study revisits the stability of the possible conformations and the decomposition reactions of ethyl formate in the S₀ state using the (U)MP2, MP4SDTQ, CCSD(T), and (U)B3LYP methods with various basis sets. The transition states of the decomposition channels to HCOOH + C₂H₄, CO + CH₃CH₂OH, CH₂O + CH₃CHO, HCOH + CH₃CHO, C₂H₆ + CO₂, and H₂ + CH₂CHOCHO are determined. The microcanonical rate constants derived from the RRKM theory are calculated for each of the decomposition reactions. The high‐pressure limit rate constants are calculated for the decomposition channels to HCOOH + C₂H₄, CO + CH₃CH₂OH, and CH₂O + CH₃CHO.     

A new series of pyrimidine-containing linear molecules: their elegant crystal structures and intriguing photophysical properties

A new series of aza-substituted analogues 3-5 based on the 1,4-bis(phenylethynyl)benzene moiety have been synthesized by the selective Pd-catalyzed Sonogashira coupling reaction from 5-bromo-2-iodopyrimidine (1). In these linear molecules, the dipolar pyrimidine moiety is introduced as a probe to investigate factors that control the intermolecular interactions over the crystal engineering. The results reveal that the manner of packing changes both dipolar interactions between linear pyrimidine-containing molecules and transition moments simultaneously, resulting in remarkably different photophysical properties. Due to their versatile dipole-dipole and face-to-face pi-piinteractions in a crystal motif, further applications on the design of ordered crystalline materials for the field effect transistors are promising.     

Effects of solute-matrix interaction on monitoring the conformational changes of immobilized proteins by surface plasmon resonance sensor

A real-time and labeling-free surface plasmon resonance (SPR) sensor was used to monitor the conformational changes of immobilized globule proteins (RNase A and lysozyme) in chemical unfolding and refolding. The effects of chemical denaturants on the protein structures were investigated. The methodology in protein conformational study on the solid surface is refined through the theoretic calculations and the conformational information of native/denatured proteins in solution. Additionally, our observation illustrates that the ambient buffer solution is merit to influence the refractive index of immobilized protein films and directly be observed from the SPR resonance angle shifts.     

Wavelet-Based Method for Time-Domain Noise Analysis and Reduction in a Frequency-Scan Ion Trap Mass Spectrometer

We adopt an orthogonal wavelet packet decomposition (OWPD) filtering approach to cancel harmonic interference noises arising from an AC power source in time domain and remove the resulting rf voltage interference noise from the mass spectra acquired by using a charge detection frequency-scan quadrupole ion trap mass spectrometer. With the use of a phase lock resampling technique, the transform coefficients of the rf interference in signals become a constant, exhibiting a shift of the baseline in different rf phases. The rf interference is therefore removable by shifting the baselines back to zero in OWPD coefficients. The approach successfully reduces the time-domain background noise from 1367 electrons (rms) to 408 electrons (rms) (an improvement of 70?%) and removes the high frequency noise components in the charge detection ion trap mass spectrometry. Unlike other smoothing or averaging methods commonly used in the mass-to-charge (m/Ze) domain, our approach does not cause any distortion of original signals.     

Textile‐based Electrochemical Sensing: Effect of Fabric Substrate and Detection of Nitroaromatic Explosives

This study examines the influence of textile substrates upon the behavior of wearable screen‐printed electrodes and demonstrates the attractive sensing properties of these sensors towards the detection of nitroaromatic explosives. Compared to electrodes printed on common cotton or polyester substrates, GORE‐TEX‐based electrochemical sensors display reproducible background cyclic voltammograms, reflecting the excellent water‐repellant properties of the GORE‐TEX fabric. The wetting properties of different printed textile electrodes are elucidated using contact angle measurements. The influence of laundry washing and mechanical stress is explored. The GORE‐TEX‐based printed electrodes exhibit favorable detection of 2,4‐dinitrotoluene (DNT) and 2,4,6‐trinitrotoluene (TNT) explosives, including rapid detection of DNT vapor.     

Dendritic Macromolecules as Inhibitors to Protein-Protein Binding

Summary: Our initial studies into protein binding using a series of dendrimers as size selective inhibitors have been described. Two different proteins, cytochromo-c and chymotrypsin have been selected for these binding experiments.     

Novel oxazabicycles as a new class of photochromic colorants

A new photochromic colorant with an oxazabicyclic moiety has been synthesized by an efficient method. It turns pale red upon UV irradiation and undergoes reverse reaction while being heated. This work may open an exciting new avenue for future development of the photochromic dyes with novel molecular structures.     

Tasumatrols P – T,Five New Taxoids from Taxus sumatrana

The phytochemical investigation of the more polar fractions from the leaves and twigs of Taxus sumatrana (Taxaceae) afforded five new taxane diterpene esters, tasumatrols P–T ( 1 – 5 ) possessing an 11(15→1),11(10→9)‐diabeotaxane skeleton. Compounds 1, 4 , and 5 contain an α‐hydroxy group at C(14), while 3 has no OH group at either C(13) or C(14). Compound 2 is a natural 4,5‐acetonide derivative, while 4 has an unusual spiro‐connected 2‐hydroxy‐2‐phenyl‐1,3‐dioxolane ring. Ten known taxoids, were also isolated in the course of the chromatographic fractionation. Five additional new O‐acetyl derivatives 3a, 4a, 4b, 5a , and 5b were prepared from the taxanes 3 – 5 . The structures of all new compounds were established on the basis of their spectroscopic analyses. Compound 1 showed mild cytotoxic activity against human Hela and Daoy tumor cells.