Ion pair assisted micro matrix solid phase dispersion extraction of alkaloids from medical plant

A novel micro matrix solid phase dispersion method was successfully used for the extraction of quaternary alkaloids in Phellodendri chinensis cortex. The elution of target compounds was accomplished with sodium hexanesulfonate as the eluent solvent. A neutral ion pair was formed between ion-pairing reagent and positively charged alkaloids in this process, which was beneficial for selectively extraction of polar alkaloids. Several parameters were optimized and the optimal conditions were listed as follows: silica gel as the sorbent, silica to sample mass ratio of 1:1, the grinding time of 1 min. The exhaustive elution of targets was achieved by 200 µL methanol/water (9:1) containing 150 mM sodium hexane sulfonate at pH 4.5. The method validation covered linearity, recovery, precision of intraday and interday, limits of detection, limits of quantitation, and repeatability. This established method was rapid, simple, environmentally friendly, and highly sensitive.     

Mechanism and Stereoselectivity of the Elementometalation Process of Activated Alkyne RCCR(RCO2Me) by Cp2TaH3

The elementometalation process is a fundamental chemical step in several catalytic cycles. In this work, density functional theory computations have elucidated the detailed elementometalation mechanism of activated alkyne RCCR(RCO₂Me) by Cp₂TaH₃ and rationalized the selectivity in experimental findings. The calculated results show that in the formation process of (E)-olefin monohydride((E)-Pro), the Gibbs free energy barrier is low and the entire reaction is spontaneous and exothermic; thus, (E)-Pro can be formed easily. The formation of (Z)-η²-olefin monohydride complex ((Z)-Pro) is difficult due to its high Gibbs free energy barrier. The formation process (E)-Pro consists of the following five steps: hydride H1-shift, conformational isomerism 1, hydride H2-shift, conformational isomerism 2, and olefin coordination process. Topological analysis shows that there is a five-membered ring plane structure in the reaction pathway and that the final product (E)-Pro belongs to a typical η²-olefin monohydride complex. Our calculated results provide an explanation for experimental observations and useful insights for further development of olefin functionalization. © 2019 Wiley Periodicals, Inc.     

(NH4)Bi2(IO3)2F5: An Unusual Ammonium-Containing Metal Iodate Fluoride Showing Strong Second Harmonic Generation Response and Thermochromic Behavior

An ammonium-containing metal iodate fluoride compound, (NH₄)Bi₂(IO₃)₂F₅, featuring a two-dimensional double-layered framework constructed by [BiO₂F₅]⁶⁻ and [BiO₄F₄]⁹⁻ polyhedra, as well as [IO₃]⁻ groups, was successfully synthesized. The well-ordered alignment of these SHG-active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (E_g=3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS₂). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.     

电化学促进铱催化乙烯基C-H键官能团化高效合成α-吡喃酮

电化学有机合成技术在过去十年来蓬勃发展,越来越受到学术和企业界合成化学工作者的青睐[1-5].跟传统化学反应相比,它的优势是利用电流代替常规的化学氧化剂或还原剂来促进化学反应,同时通过电势的调节,实现独特的反应性和化学选择性.电化学和过渡金属协同催化的碳氢键官能团化修饰(C-Hfunctionalization),不仅有效避免底物的预官能团化,而且为逆合成分析提供了可能的新颖断键方法,日益成为一种更为绿色经济的反应类型[6].     

氰基亚胺与亚甲基二氢苯并呋喃二酮类化合物的[3+2]环加成反应:螺吡唑类化合物的合成

采用具有环外双键的二氢苯并呋喃二酮类化合物和氰基亚胺的[3+2]环加成反应,在温和条件下,以高产率(78%~94%)和高非对映选择性(>20∶1dr)构建了一系列具有螺环结构的吡唑类化合物.     

Efficient removal of As(V) from simulated arsenic-contaminated wastewater via a novel metal–organic framework material: Synthesis,structure, and response surface methodology

A novel metal–organic framework material {[N(C₂H₅)₃][Zn₂(ptmda)₂(μ₂-H₂O)]·(H₂O)_0.5}_n { GUT-3 ; H₂ptmda is 4,4′-([p-tolylazanediyl]bis [methylene])dibenzoic acid} was successfully synthesized using the hydrothermal method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. GUT-3 has a two-dimensional network based on dinuclear [Zn₂(ptmda)₂(μ₂-H₂O)]⁻ building units which formed an eightfold interpenetration network in GUT-3 molecules. Hirshfeld surface analysis revealed that H–H, C–H, and O–H bonds accounted for the majority of intermolecular interactions. Moreover, the interactions between GUT-3 and As(V) – the form of As(V) is AsO₄³⁻ – were analyzed in aqueous solutions in a batch system to study the effect of pH, concentration, adsorbent dose, adsorption time, adsorption temperature, and shaking speed. The kinetic and isotherm data of arsenic adsorption on GUT-3 were accurately modeled by pseudo-second-order, Langmuir (q_m = 33.91 mg/g), and Freundlich models. The Box–Behnken response surface method was used to optimize the adsorption conditions of As(V) from the simulated arsenic-contaminated wastewater. The effect of various experimental parameters and optimal experimental conditions was ascertained using the quadratic model.     

Optimal spectral phase control of femtosecond laser-induced up-conversion luminescence in Sm^3+:NaYF4 glass

The spectral phase of the femtosecond laser field is an important parameter that affects the up-conversion(UC)luminescence efficiency of dopant lanthanide ions.In this work,we report an experi-mental study on controlling the UC lmiiinescence efficiency in Sm^3+:NaYF4 glass by 800-nm femtosec-ond laser pulse shaping using spectral phase modulation.The optimal phase control strategy efficiently enhances or suppresses the UC luminescence intensity.Based on the laser-power dependence of the UC luminescence intensity and its comparison with the luminescence spectrum under direct 266-nm fem-tosecond lciser irradiation,we propose herein an excitation model combining non-resonant two-photon absorption with resonance-media ted three-photon absorption to explain the experimental observations.     

Eco-friendly solution processing of all-polymer solar cells: Recent advances and future perspective

All-polymer solar cells (all-PSCs) exhibit great potentials in commercial applications. All-PSCs have observed steady performance gains with power conversion efficiency now reaching over 17% in the open literature. However, the current processing of all-PSCs relies predominantly on toxic, chlorinated solvents in moisture-free environments, representing a significant barrier for their commercialization due to the added costs to handle and dispose of such solvents. There is thus an urgent need for safe, environmentally benign, and sustainable ink-based processing methods to produce all-PSC devices reliably and reproducibly in ambient air. In this perspective, fundamental insights on the interplay between all-polymer blend morphologies and eco-friendly solvents are provided. Also, we discuss the recent successes of the green processing methods to manipulate the photoactive morphologies for high-efficiency all-PSCs. In the end, we provide an outlook on future challenges and opportunities of eco-friendly solvents processed all-PSCs for large-scale manufacturing.