ZIF-67@PDA/含氟聚酰亚胺混合基质膜的制备及其气体分离性能

混合基质膜结合聚合物膜的柔韧性和多孔填料的气体分离性能,近年来在气体分离领域被广泛关注。共价有机框架材料(COFs)具有高比表面积、高孔隙率、易功能化等特点,其全有机的结构展现出与聚合物之间良好的相容性,被认为是混合基质膜理想填料之一。因此,本研究通过溶剂热法合成了氟化共价有机框架材料TpPa-CF₃,采用共混法以TpPa-CF₃为填料,聚酰亚胺6FDA-ODA为基体制备TpPa-CF₃/6FDA-ODA混合基质膜。通过傅里叶红外光谱(FT-IR)、X-射线衍射(XRD)、热重分析(TGA)、扫描电子显微镜(SEM)和气体渗透性等测试对TpPa-CF₃及其混合基质膜进行结构与性能的研究。结果表明,TpPa-CF₃均一的孔道为气体分子传输提供了快速通道,框架的微孔结构增强了气体分子与孔壁上功能基团的相互作用。当TpPa-CF₃负载量为5 wt%时,CO₂和O₂渗透性相较于6FDA-ODA基体膜分别提高了149%和138%,CO₂/N₂和O₂/N₂分离因子分别提升到24.4和4.8。

     

A composite prepared from covalent organic framework and gold nanoparticles for the electrochemical determination of enrofloxacin

A high conductivity composite based on covalent organic frameworks/gold nanoparticles (TAPB-PDA-COFs/AuNPs, TAPB: 3,5-tris(4-aminophenyl)benzene, PDA: p-phthalaldehyde) was prepared by a simple in-situ synthesized method and a novel electrochemical sensor based on TAPB-PDA-COFs/AuNPs was constructed for detection of Enrofloxacin (ENR). A variety of different characterization techniques including ultraviolet‐visible spectrophotometer (UV–vis), fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the TAPB-PDA-COFs/AuNPs. ENR was detected by square wave stripping voltammetry (SWV) according to the relationship between the ENR concentration and the oxidation peak current. The result showed that TAPB-PDA-COFs/AuNPs was synthesized successfully. The electrochemical sensor showed two linear ranges in the range of 0.05–10 μmol L^?1 and 10–120 μmol L^?1 with the limit of detection of 0.041 μmol L^?1 (S/N = 3). The good recoveries (96.7–102.2%) and low RSDs (0.9–6.4%) indicated the possibility of using this sensor for actual sample detection. Therefore, TAPB-PDA-COFs/AuNPs-based electrochemical sensor showed good performance in detecting ENR, and would be a potential candidate for the development of fluoroquinolones determination.     

Molecular Semiconductors for Logic Operations: Dead-End or Bright Future?

The field of organic electronics has been prolific in the last couple of years, leading to the design and synthesis of several molecular semiconductors presenting a mobility in excess of 10 cm² V⁻¹ s⁻¹. However, it is also started to recently falter, as a result of doubtful mobility extractions and reduced industrial interest. This critical review addresses the community of chemists and materials scientists to share with it a critical analysis of the best performing molecular semiconductors and of the inherent charge transport physics that takes place in them. The goal is to inspire chemists and materials scientists and to give them hope that the field of molecular semiconductors for logic operations is not engaged into a dead end. To the contrary, it offers plenty of research opportunities in materials chemistry.     

A DFT study on Pt single atom loaded COF for efficient photocatalytic CO2 reduction

Photocatalytic CO2 reduction provides a promising strategy for the alleviation of greenhouse effect and energy shortage problem.Metal single atom modification is an effective method to improve the CO2 re-duction performance of covalent organic framework(COF)photocatalysts,while the intrinsic mechanism is not revealed in depth.Herein,a Pt-COF photocatalytic system was constructed by embedding Pt sin-gle atom in TFPT-TMT-COF(TFPT:1,3,5-tris(4-formylphenyl)-triazine,TMT:2,4,6-trimethyl-1,3,5-triazine).Based on density functional theory(DFT)calculation,the geometric structure and electronic property of Pt-COF were investigated,and the CO2 adsorption and reduction reaction process on Pt-COF were simu-lated.The results show that the Pt atom can be steadily anchored in COF via the formation of Pt-N and Pt-C bonds.Moreover,there is strong electronic interaction between Pt and COF.The incorporation of Pt atom benefits the CO2 reduction activity of COF from multiple aspects:(ⅰ)reducing the band gap and improving light absorption;(ⅱ)enhancing CO2 adsorption and activating the CO2 molecule;(ⅲ)decreas-ing the energy barrier in the hydrogenation step of CO2→COOH,thus facilitating CO2 conversion to CO;(ⅳ)inhibiting the hydrogenation of CO,thereby increasing the selectivity of CO.This work brings a novel insight into the excellent CO2 reduction performance of Pt modified COF,and provides useful references for the design of single atom photocatalysts.     

Silicon-based molecular switch junctions

In contrast to the static operations of conventional semiconductor devices, the dynamic conformational freedom in molecular devices opens up the possibility of using individual molecules as new types of devices such as a molecular conformational switch or for molecular data storage. Bistable molecules—such as those having two stable cis and trans isomeric configurations—could provide, once clamped between two electrodes, a switching phenomenon in the non-equilibrium current response. Here, we model molecular switch junctions formed at silicon contacts and demonstrate the potential of such tunable molecular switches in electrode/molecule/electrode configurations. Using the non-equilibrium Green function (NEGF) approach implemented with the density-functional-based tight-binding (DFTB) theory, a series of properties such as electron transmissions, current-voltage characteristics in the different isomer conformations, and potential energy surfaces (PESs) as a function of the reaction coordinates along the trans to cis transition were calculated for two azobenzene-based model compounds. Furthermore, in order to investigate the stability of molecular switches under ambient conditions, molecular dynamics (MD) simulations at room temperature were performed and time-dependent fluctuations of the conductance along the MD pathways were calculated. Our numerical results show that the transmission spectra of the cis isomers are more conductive than trans counterparts inside the bias window for both model compounds. The current voltage characteristics consequently show the same trends. Additionally, calculations of the time-dependent transmission fluctuations along the MD pathways have shown that the transmission in the cis isomers is always significantly larger than that in their trans counterparts, showing that molecular switches can be expected to work as robust molecular switching components. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users.