Significant progress has been made in the research of stimuli-responsive materials in recent years. Among these, viologen-based functional coordination compounds have shown remarkable prominence due to the excellent redox properties of viologens. Herein, a pi-conjugation extension strategy was employed by introducing a diphenyl sulfone group between the viologen pyridine units to enhance its performance. Using this extended viologen 4,4 '-(sulfonylbis(4,1-phenylene))bis(1-(4-carboxybenzyl)pyridin-1-ium) chloride [(H2L)center dot 2Cl] as a ligand, with d(10) configured metals (Zn2+/Cd2+) as central atoms and terephthalic acid (PTA) as an auxiliary ligand, two novel crystalline materials {[Zn(L)(PTA)(H2O)]center dot 4H(2)O}(n) (1) and {[Cd(L)(PTA)(0.5)(FA)]center dot 6H(2)O}(n) (2) were successfully constructed. Both materials exhibit rapid and reversible photochromic behavior. The mechanism for this photochromic behavior is attributed to electron transfer from carboxylate groups and water molecules to viologen pyridine nitrogen atoms. Furthermore, the materials possess excellent electrochromic properties, showing good reversibility in air and a specific color change response toward amine vapors. This work aims to develop stimuli-responsive materials that combine structural stability with functional diversity, thereby enriching the range of materials available in this field.

Multistimuli-responsive crystalline materials have a wide range of application prospects. However, development of new multistimuli-responsive materials remains full of challenge. In this work, taking a symmetrical modified extended viologen (ExV)-based carboxylate 1,1-bis(4-carboxybenzyl)-2,5-bipyridyl thiophene dichloride (H2LCl-2) as a ligand and terephthalic acid (PTA) as an auxiliary ligand, a multistimuli-responsive crystalline 3D MOF material {[Cd-2(L)(PTA)(2)]3H(2)O}(n) (Cd-MOF-1) was constructed successfully. Cd-MOF-1 shows distinctive photochromic and electrochromic properties, which can be attributed to the formation of viologen radicals induced by electron transfer (ET) under external photo/electricity stimuli. Furthermore, the title compound also displays photomodulable fluorescence and sensitive and distinguishable color response to propylamine (PA) vapor relative to other amine molecules. The distinguishable selectivity toward volatile amine vapors may be caused by the differences in the size or electron propelling capacity of the amines. In addition, the photochromic character of the title compound makes it suitable for ink-free erasable printing. This excellent multistimuli-responsive material may have more potential application values in the areas of photoelectric devices, light printing, volatile amine detection, etc. It is also helpful for us to further explore and develop MOF-based multistimuli responsive materials constructed by ExV derivatives.

Green ammonia synthesis through electrocatalytic nitrate reduction reaction (eNO3RR) can serve as an effective alternative to the traditional energy-intensive Haber-Bosch process. However, achieving high Faradaic efficiency (FE) at industrially relevant current density in neutral medium poses significant challenges in eNO3RR. Herein, with the guidance of theoretical calculation, a metallic CoNi-terminated catalyst is successfully designed and constructed on copper foam, which achieves an ammonia FE of up to 100% under industrial-level current density and very low overpotential (-0.15 V versus reversible hydrogen electrode) in a neutral medium. Multiple characterization results have confirmed that the maintained metal atom-terminated surface through interaction with copper atoms plays a crucial role in reducing overpotential and achieving high current density. By constructing a homemade gas stripping and absorption device, the complete conversion process for high-purity ammonium nitrate products is demonstrated, displaying the potential for practical application. This work suggests a sustainable and promising process toward directly converting nitrate-containing pollutant solutions into practical nitrogen fertilizers.

Capacitive deionization (CDI) is a promising desalination technology, and metal-organic framework (MOF)-derived carbon as an electrode material has received more and more attention due to its designable structure. However, MOF-derived carbon materials with single-pore structures have been difficult to meet the technical needs of related fields. In this work, the ordered hierarchical porous carbon framework (OMCF) was prepared by the template method using zeolitic imidazolate frameworks-8 (ZIF-8) as a precursor. The pore structures, surface properties, electrochemical properties, and CDI performances of the OMCF were investigated and compared with the microporous carbon framework (MCF), also derived from ZIF-8. The results show that the hierarchical porous carbon OMCF possessed a higher specific surface area, better hydrophilic surface (with a contact angle of 13.45°), and higher specific capacitance and ion diffusion rate than those of the MCF, which made the OMCF exhibit excellent CDI performances. The adsorption capacity and salt adsorption rate of the OMCF in a 500 mg·L-1 NaCl solution at 1.2 V and a 20 mL·min-1 flow rate were 12.17 mg·g-1 and 3.34 mg·g-1·min-1, respectively, higher than those of the MCF. The deionization processes of the OMCF and MCF closely follow the pseudo-first-order kinetics, indicating the double-layer capacitance control. This work serves as a valuable reference for the CDI application of N-doped hierarchical porous carbon derived from MOFs.

Capacitive deionization(CDI)is a promising technology for removing salt from brackish water,and the desalination performance greatly depends on the structures and properties of electrode materials.In this work,the ZIF-67 was used as a precursor to obtain three ZIF-67-derived porous carbon nanomaterials including carbon nano-box(ZCNB),carbon nanotubes(ZCNT),and carbon nano-box and carbon nanotube hybrids(ZCNH).The pore structures,surface properties,electrochemical properties,CDI performances of three porous carbon nanomaterials and constitutive relationships were investigated.The results show that among three ZIF-67-derived nanostructured carbon materials,ZCNB has the highest adsorption capacity because of its high specific surface area,good wettability,high surface charge,and suitable pore sizes.Though the carbon nanotubes in the ZCNH and ZCNT could improve the electrical conductivity of the material,it leads to a decrease in the specific surface area and wettability,thereby reducing the adsorption capacity.This work would provide a reference for the design of MOFs-derived CDI electrode materials.

A one-dimensional Cd(II) chain coordination polymer constructed by an electron-deficient viologen-anchored carboxylate ligand was successfully synthesized. Owing to the favorable stimuli-chromic properties of viologen, the title compound shows reversible photochromism, thermochromism, electrochromism, and naked-eye-detectable differentiable vapochromic response to different volatile amines. The chromic behaviors of it are ascribed to the formation of viologen radicals triggered by external stimuli. And the differentiated response to volatile amines is attributed to the size effect of the amines as well as the steric hindrance effect of forming α/β Cv-H···Namines interactions of the viologen unit to further affect the occurrence of electron transfer. Such an all-in-one crystalline material might have more practical applications in photoelectric, erasable inkless printing, light printing, and volatile amine detection fields.

Various research groups around the globe are focusing on the design and development of innovative luminescent systems, because of their multiple and unique features such as remarkable sensitivity, rapid signal response time, and ease of operation. In particular, aggregation-induced emission (AIE) based luminescent frameworks have emerged as potential candidates for sensing applications owing to the distinct emission property of AIE luminogens (AIEgens). Thus, numerous AIEgen-based porous materials like metal organic frameworks (MOFs), covalent organic frameworks (COFs), porous organic polymers (POPs), and metal organic cages (MOCs) have been established over the past decade for sensing applications with exceptional performances that surpass the conventional luminescent probes. This review provides systematic information on the fundamentals of AIE, the operating mechanism involved, and finally sheds light on recent advancements in AIE-based luminescent porous materials (MOFs, COFs, POPs, and MOCs) for potential sensing applications with special emphasis on environmental safety. The important detection parameters such as sensitivity, response time, selectivity, etc., of such AIE porous materials are highlighted for the detection of a variety of chemical compounds. (c) 2022 Elsevier B.V. All rights reserved.

Stable stimulus-responsive materials are highly desirable due to their widespread potential applications and growing demand in recent decades. Despite the fact that viologen derivatives have long been known as excellent photochromic and electrochromic materials, the development of stable viologen-based multifunctional smart materials with short coloration times remains an exciting topic. To obtain photochromic and electrochromic dual responsive materials, embedding the viologen ligand into a robust metal oxide cluster to increase its stability and sensitivity is an effective strategy. Herein, a viologen-based metal-organic polyhedron (MOP) {[Zr6L3(μ3-O)2(μ2-OH)6Cp6]·8Cl·CH3OH·DMF} [Zr-MOP-1; H2L·2Cl = 1,1'-bis(4-carboxyphenyl)-4,4'-bipyridinium dichloride, and Cp = η5-C5H5] was successfully prepared and characterized. It consists of trinuclear Zr-oxygen secondary building units and exhibits reversible photochromic and electrochromic dual responsive behaviors. As expected, the designed robust viologen-based nanocage with a V2E3 (V = vertex, and E = edge) topology can maintain its stability and rapid photo/electrochromic behaviors with an obvious reversible change in color from purple (brown) to green, mainly due to the enclosed cluster structure and the abundant free viologen radicals that originate from the effective Cl → N and O → N electron transfers. Spectroelectrochemistry and theoretical calculations of this Zr-MOP were also performed to verify the chromic mechanism.

教学过程中从所要讲授的知识点着手,通过各种手段引导学生实现教学目标.通过行动导向教学,教师在教学过程中把大任务分解成小任务,然后分层次地给学生下达行动导向,通过多种教学方法的结合从而达到学习、认知、理解、掌握知识的目的.

The design and development of carbon materials with high-efficiency oxygen reduction activity is still a problem. Folic acid (FA) has unique structural characteristics, and it can provide multiple coordination sites for metal ions. Here, folic acid (FA) was used as a metal complex ligand, and Cu-Co-based N-doped porous carbon nanosheets (Cu-CoNCNs) were synthesized by the solvothermal method, the molten salt template-assisted calcination method, and the chemical etching method. The Cu-CoNCNs synthesized by this method have highly efficient oxygen reduction reaction (ORR) activity. In 0.1 mol/L KOH electrolytes, the catalyst exhibits excellent ORR activity and has a fairly high half-wave potential (0.905 V vs reversible hydrogen electrode (RHE)). X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, infrared spectroscopy, and X-ray diffraction (XRD) were used to investigate the reasons why the catalyst has excellent catalytic activity and long-life stability. It was proved that the impressive ORR activity of Cu-CoNCNs comes from Cu doping, which can regulate the surface electronic structure of the catalyst, thereby optimizing the binding ability between the intermediate and adsorbed species and improving the catalytic activity.

Metal nitrogen-carbon catalysts have become a promising alternative to platinum-based catalysts in fuel cells due to their high stability and platinum-like activity. However, the corrosion and deactivation of active sites in the solution still restrict the inherent reaction kinetic rate. For this reason, it is important to stabilize the catalyst through a controllable doping strategy to obtain high activity catalysts for oxygen reduction reactions (ORR). Herein, the pyrolysis strategy is demonstrated in the synthesis of iron-based catalysts co-doped with nitrogen and biomass-derived phosphorus (denoted as N, P-Fe/C), and the pore size of the catalyst is mostly distributed at 1 nm or 50 nm, respectively. The half-wave potential (0.893 V) and the current density (4.05 mA cm−2) at 0.85 V of the catalyst exceed those of the commercial Pt/C. The remarkable ORR performance can be attributed to its distinct hierarchical pore structure, the modulation effect of nitrogen and phosphorus co-doping on the carbon matrix, and the combined effect of the FeNx active sites, which improves the accessibility of reactants and accelerating the absorption/desorption of the reaction intermediate, thereby increasing reaction rates. And N, P-Fe/C has great potential as a promising substitute for platinum-based catalysts.

Two lanthanide coordination polymers (CPs) {[Er(Hmtbd)(H2mtbd)(H2O)3]·2H2O}n (1) and [Yb(Hmtbd)(H2mtbd)(H2O)3]n (2) carrying an N-heterocyclic carboxylate ligand 5-(3-methylformate-1H-1,2,4-triazole-1-methyl)benzen-1,3-dicarboxylate (H3mtbd) were prepared under solvothermal conditions. The single-crystal X-ray diffraction data demonstrate that 1 and 2 are isostructural and display 1D chain structure. Alternating current (AC) impedance measurements illustrate that the highest proton conductivities of 1 and 2 can attain 5.09 × 10-3 and 3.09 × 10-3 S·cm-1 at 100 °C and 98% relative humidity (RH), respectively. The value of 1 exceeds those of most reported lanthanide-based crystalline materials and ranks second among the described Er-CPs under similar conditions, whereas the value for 2 is the highest proton conductivity among the previous Yb-CPs. Coupled with the structural analyses of the two CPs and H2O vapor adsorption, the calculated Ea values help to deduce their proton conductive mechanisms. Notably, the N-heterocyclic units (triazole), carboxyl, and hydrogen-bonding network all play key roles in the proton-transfer process. The prominent proton conductive abilities of both CPs show great promise as efficient proton conductors.

A novel 0D organic-inorganic metal halide hybrid (C13H16N2O2)2InCl6·Cl (1) has been obtained by integrating the mono-viologen derivative with InCl3. Compound 1 exhibits reversible and ultrafast UV/sunlight/X-ray induced photochromic properties, as well as excellent electrochromic performance, which is the first example of an indium-based organic-inorganic chromic hybrid.

As one of the important subclasses of MOFs, Alkaline earth (group II) metal-organic frameworks (AEMOFs) in recent years also have caught much attention not only because of their fascinating structures but also because of their nontoxicity, relatively low densities, low cost and stability, etc. These merits make them have many potential applications in implementation and industrial fields. In this review, we will give a succinct description of the recent development on the AEMOFs (including the homometallic and heterometallic AEMOFs): some representative structures and physicochemical properties, such as proton conductivity, magnetism, gas or guest adsorption/separation, chromism, heterogeneous catalysis, biomedical applications, as well as luminescent sensing, are presented in this review. Fully understanding the structure-property relationship of the AEMOFs is still a long way, we hope this review could give some inspirations and help to chemists to explore the syntheses and applications of the AEMOFs in much more fields. (C) 2021 Elsevier B.V. All rights reserved.

The introduction of sulfur is beneficial to regulate the electronic structure of M-Nx active site, thus improving oxygen reduction reactions (ORR) catalytic activity. Herein, we adopted a hydrogel method to synthesize ORR catalyst of Co metal atom dispersed on N and S co-doped tremelliform carbon (Co/NSTFC). The as-synthesized catalyst was characterized by TEM, XRD and BET, and results demonstrated that cobalt atoms are highly dispersed on porous N and S co-doped tremelliform carbon, and the specific surface area is as high as 1613 m2 g−1. And XPS analysis confirms the formation Co-Nx coordination bond, while the sulfur atom is successfully doped on the carbon support. The XPS analysis of N 1s and Co 2p prove that the introduction of sulfur atoms can improve the efficiency of electron transferring to graphite nitrogen, and to the vicinity of Co-Nx, thus increasing d-band center of Co metal atoms, consequently improving the oxygen reduction activity. The Co/NSTFC catalyst exhibits high-efficient ORR activity with half-wave potential (E1/2) of 0.882 V in 0.1 M KOH. Furthermore, the measured number of electron transfer is close to 4, and a low yield of hydrogen peroxide and superior stability were confirmed with the Co/NSTFC catalyst. This study provides new insights into the design and synthesis of high the performant ORR catalysts and promoting the development of energy conversion.

Developing promising luminescent probes for the selective sensing of nitro-explosives remains a challenging issue. Porous luminescent covalent-organic polymers are one of the excellent sensing probes for trace hazardous materials. Herein, fluorescent monomers 1,1,2,2-tetrakis(4-formyl-(1,1'-biphenyl))ethane (TFBE) and 1,3,5-benzenetricarboxylic acid trihydrazide (BTCH) were selected to build a novel hydrazone connected stable luminescent covalent-organic polymer (H-COP) of high stability by typical Schiff-base reaction. The N2 sorption study, BET surface area analysis, and TGA profile indicate the porosity and stability of this H-COP material. Such properties of the H-COP material enable a unique sensing platform for nitro-explosives with great sensitivity (Ksv ∼ 106 M) and selectivity up to μM. This polymer material shows attractive selectivity and sensitivity towards phenolic nitro-explosives and other common explosives among earlier reported COP-based sensors.

A novel Cd-based MOF shows high sensitivity (Ksv ∼ 106 M−1) and selectivity (μM level) towards antibiotics was presented.

"头脑风暴法"教学改变了传统的"填鸭式"教学模式,重视学生在《普通化学》学习过程中的主动性,通过开放式思考、讨论的方式,提高学生学习《普通化学》的趣味性、积极性,激发学生在化学学习过程中的兴趣,拓宽学生的视野与知识面,加深学生的学习印象,改变他们的学习方法,让学生在学习的过程中享受探索知识的乐趣.将"头脑风暴法"引入教学过程中能够激发学生的学习热情,有利于学生分析解决问题能力和创新思维能力的培养.

Metal-organic framework (MOF) derived hybrid materials have been developed as an efficient non-noblemetal electrocatalysts for clean energy conversion systems. In this work, a Co-based MOF containing nitrogen and oxygen heteroatoms (Co-NOMOF) mixed with the thiomolybdate [Mo3S13](2-) nanoclusters was used to prepare the N, S, O-doped carbon encapsulating Co9S8 and MoS2 (Co9S8/MoS2@NSOC) nanocomposite by one-step pyrolysis. The Co9S8/MoS2@NSOC nanocomposite exhibited remarkable catalytic performance for hydrogen evolution reaction (HER) with overpotential of 194 and 233 mV in 1 M KOH and 0.5 M H2SO4 solution under 10 mA cm(-2), respectively, which was ascribed to the multiheteroatom-doped hierarchical porous carbon matrix and the synergistic effect of intrinsic activity of Co9S8 and MoS2. This work provides new opportunity for developing highly efficient non-precious metal electrochemical catalysts. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.