Tetra-alkylsulfonate functionalized poly(aryl ether) membranes with nanosized hydrophilic channels for efficient proton conduction

The microstructure of polymer electrolyte membranes plays a key role in ion conductivity and water transport.Herein,fluorinated poly(aryl ether)s with tetra-alkylsulfonate side chains(SFPAEs)have been successfully synthesized from the copolymerization of a newly developed tetra-allyl-containing bisphenol(TABP)monomer,followed by the thiol-ene addition with sodium 3-mercapto-1-propanesulfonate to attach the ionic groups at the end of the flexible chains.Being the first of its kind,the densely distributed and lengthy alkylsulfonate group possesses the benefit of ease to self-assemble into hydrophilic domains during membrane preparation via solution casting.Indeed,the TEM characterizations revealed that distinct hydrophilic channels of 1-2 nm width had been formed,much larger than those of a home-made control sample where only di-alkylsulfonate side chains were attached.The SFPAE-4-45 with an IECw of 2.0 mmol g^-1 exhibited an enhanced proton conductivity of 143.7 m S cm^-1 at room temperature,which was superior to that of Nafion 212(91.0 m S cm^-1).Furthermore,the oxidative stabilities of SFPAEs were significantly higher than those of non-fluorinated analogs in literature.This study offered a new route to engineering the pendent structure of ionomers for well-defined microscopic morphologies.

Efficient and Fast X-Ray Luminescence in Organic Phosphors Through High-Level Triplet-Singlet Reverse Intersystem Crossing

Organic scintillators that efficiently generate bright triplet excitons are of critical importance for highperformance X-ray-excited luminescence in radiation detection.However,the nature of triplet-singlet spinforbidden transitions in these materials often result in long-lived phosphorescence,which is undesirable for ultrafast X-ray detection and imaging.Here we demonstrate that the effect of hybridized local and charge-transfer(HLCT)excited states enables organic scintillators to exhibit highly efficient and fast radioluminescence(RL)in response to X-ray irradiation.Our experimental and theoretical investigation shows that the oxidized 1,8-naphthalimide-phenothiazine dyad(OMNI-PTZ 2)with HLCT-excited states has an enhanced overlap integral of the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)on MNIπ-orbitals,and moderate donor–acceptor electron interactions.As a result,the RL of these crystals exhibits a 61-fold increase and its monoexponential decay lifetime is three orders of magnitude faster compared to its corresponding thermally activated delayed fluorescence(TADF)molecule MNI-PTZ 1.We further demonstrate the practical utility of the OMNI-PTZ 2(G)in high-performance X-ray detection and imaging,achieving an X-ray dose sensitivity of 97 nGy s−1 and an exceptional spatial resolution of 20 lp/mm.Our study provides a promising molecular design principle for utilizing triplet excitons to develop high-efficiency and fast X-ray scintillators for the development of next-generation flexible and stretchable X-ray imaging detectors.

Photoactive donor-acceptor conjugated macrocycles:New opportunities for supramolecular chemistry

The design and synthesis of photoactive macrocyclic molecules continue to attract attention because such species play important roles in supramolecular chemistry as well as photoelectronic applications.Donoracceptor(D-A)conjugated macrocycles are an emerging class of photoactive molecules due to their D-A conjugated structural characteristics and tunable optical properties.In addition,the well-defined cavities in such D-A macrocycles endow them with versatile host-guest properties.In this review,we provide a comprehensive summary of D-A conjugated macrocycle chemistry,detailing recent progress in the area of synthetic methods,optical properties,host-guest chemistry and applications of the underlying chemistry to chemical sensors,bioimaging and photoelectronic devices.Our objective is to provide not only a review of the fundamental findings,but also to outline future research directions where D-A conjugated macrocycles and their constructs may have a role to play.

The 10^(th)macrocylic arene supramolecular chemistry symposium

In the last few decades,there has been a rapid emergence and growing interest in synthetic macrocyclic arenes,such as calixarenes[1,2],cyclophanes[3],cyclotriveratrylenes[4],pillararenes[5-7],and other novel macrocyclic arenes[8-10].These molecules have garnered significant attention in supramolecular chemistry for their fascinating structures,intrinsic cavities,ease of structural and property modifications and wide range of applications[11-14].

Selectivity enhancement of quaternized poly(arylene ether ketone)membranes by ion segregation for vanadium redox flow batteries

Quaternary ammonium densely functionalized octa-benzylmethyl-containing poly(arylene ether ketone)s(QA-OMPAEKs) with ion exchange capacities(IECs) ranging from 1.23 to 2.21 mmol g^(-1) were synthesized from:(1) Ullmann coupling extension of tetra-benzylmethyl-containing bisphenol A;(2) condensation polymerization with activated dihalide in the presence of K_2CO_3;(3) selective bromination using N-bromosuccinimide; and(4) quantitative quaternization using trimethylamine. Both smallangle X-ray scattering(SAXS) and transmission electron microscope(TEM) characterizations revealed distinct nano-phase separation in QA-OMPAEKs as a result of the dense quaternization. The QA-OMPAEK-20 with an IEC of 1.98 mmol g^(-1) exhibited a high SO_4^(2-) conductivity of 11.4 mS cm^(-1) and a low VO^(2+) permeability of 0.06×10^(-12) m^2 s^(-1) at room temperature,leading to a dramatically higher ion selectivity than Nafion N212. Consequently, the vanadium redox flow battery(VRFB)assembled with QA-OMPAEK-20 achieved a Coulombic efficiency of 96.9% and an energy efficiency of 84.8% at a current density of 50 mA cm^(-2), which were much higher than those of the batteries assembled with Nafion N212 and a home-made control membrane without distinct nano-phase separation. Therefore, ion segregation is demonstrated to be a strategical route for the design of high performance anion exchange membranes(AEMs) for VRFBs.

侧链多阳离子型氟化聚芴醚阴离子交换膜及其全钒液流电池性能

阳离子基团的分布对阴离子交换膜的微观相态和阴离子传导率有显著的影响.为开发全钒液流电池用高性能阴离子交换膜,本文通过向含有二甲胺基团的氟化聚芴醚前驱体接枝含阳离子烷基链的方式,合成了具有相似离子交换容量的一系列侧链多阳离子型氟化聚芴醚.实验结果表明,多阳离子侧链的引入能促进微观相分离的形成并提升阴离子传导率.同时,侧链季铵盐离子间的链段原子数可以通过膜的吸水率影响阴离子传导率.具有6个C原子间隔链段的侧链双阳离子DQA-PFE-C6表现出最高的阴离子传导率与选择性.以DQA-PFE-C6为隔膜组装的全钒液流电池在250 mA cm^-2下测得最大能量密度239.80 mW cm^-2,远优于以Nafion^TM 212为隔膜的全钒液流电池.可见,合理的侧链结构设计是提高全钒液流电池用阴离子交换膜性能的有效化学方法.

A novel conformationally adaptive macrocyclic tetramaleimide with flipping pyrene sidewalls

The synthesis,structure,and properties of pyrene-based conformationally adaptive macrocycles are described.This new type of conformationally adaptive macrocycle was constructed through Perkin reaction,followed by imidization.By changing the condensation partner as the linking unit,a family of conjugated macrocycles with different sizes of the cavity was synthesized,which provide a simple and modular synthetic strategy towards the conformationally adaptive macrocycles.Furthermore,the macrocycles provide two well-defined conformations through flipping pyrene subunit,which were unambiguously determined by single-crystal X-ray diffraction analysis.The conformational interconversion barrier was determined by density functional theory(DFT)calculations.This new macrocycle also demonstrated unique properties,such as vapochromic behavior and aggregation emission enhancement effect.Furthermore,we have also investigated the effect of the linker on the shape and photophysical properties of the resulting macrocyclic products.

Recent advances in metal-organic frameworks for X-ray detection

Metal-organic frameworks(MOFs)are a class of fascinating supramolecular crystalline materials that have been widely developed for catalysis,gas storage,illumination,drug delivery/cytoprotection,and so on.Recently,MOFs have been found to have potential applications in X-ray detection due to their high sensitivity,fast response time,high absorption coefficient,and radiation stability.In this review,we present an overview on the fundamental mechanism of using MOFs for X-ray scintillation.We further discuss the recent developments in X-ray detection based on indirect X-ray scintillation and direct X-ray conversion.Finally,we provide a summary and a perspective on the future of this promising research field.

1,1’-Binaphthol annulated perylene diimides: Aggregation-induced emission enhancement and chirality inversion

Aggregation-induced emission enhancement and aggregation-induced chirality inversion are two individ-ual phenomena for the enantiomerically pure organic dyes in the aggregates.Herein we reported for the first time that these two interesting phenomena could be observed simultaneously in the aggregated states of enantiomerically pure S/R-1,1?-binaphthol annulated perylene diimides,in which two perylene diimides moieties were bridged by S/R-1,1?-binaphthol(BINOL)at the bay positions.Owing to the rotat-able C2 axes between two naphthol annulated perylene diimides moieties,both of them display intrinsic behaviors of aggregation-induced emission enhancements.At the same time,due to the steric hindrances in the imide and methoxy positions,the neighboring twoπ-systems of these two unique polycyclic aro-matic imides in poor solvents are preferable to adopt a cross-stacking mode and thus form helical X-aggregates of opposite chirality(M/P)with chirality inversion characteristics in their circular dichroism and circularly polarized luminescence spectroscopic studies.

The impact of vertical π-extension on redox mechanisms of aromatic diimide dyes

Aromatic diimide dyes are an attractive class of redox-active organic molecules for lithium-ion batteries,whose battery performances(stabilities,conductivities and cyclicities) are strongly dependent on the sizes of their π-systems.However,due to the different Clar’s structures possessed,three vertically7 r-extended aromatic diimides,namely,naphthalene diimide(two one-electron reductions),perylene diimide and terrylene diimide(two one-electron reductions),exhibit different electronic redox mechanisms when served as cathode materials in organic lithium-ion batteries.Herein,we have studied carefully the different electrochemical characteristics of the three aromatic diimides through experimental and theoretical calculations.Their battery present different shape of charge/discharge curves resulting from stability of their reduction state during charge/discharge process.Terrylene diimide shows better cycle and rate capacities than those of naphthalene diimide and perylene diimide,which could be attributed to the more energies released during terrylene diimide combining with lithium ions than those of other two diimides.