Functional Polymers as Artificial Solid Electrolyte Interfaces for Stabilizing Lithium Metal Anode.

The practical implementation of the lithium metal anode (LMA) has long been pursued due to its extremely high specific capacity and low electrochemical equilibrium potential. However, the unstable interfaces resulting from lithium ultrahigh reactivity have significantly hindered the use of LMA. This instability directly leads to dendrite growth behavior, dead lithium, low Coulombic efficiency, and even safety concerns. Therefore, artificial solid electrolyte interfaces (ASEI) with enhanced physicochemical and electrochemistry properties have been explored to stabilize LMA. Polymer materials, with their flexible structures and multiple functional groups, offer a promising way for structurally designing ASEIs to address the challenges faced by LMA. This Concept demonstrates an overview of polymer ASEIs with different functionalities, such as providing uniform lithium ion and single-ion transportation, inhibiting side reactions, possessing self-healing ability, and improving air stability. Furthermore, challenges and prospects for the future application of polymeric ASEIs in commercial lithium metal batteries (LMBs) are also discussed.

Stabilizing Lithium Metal Batteries by Synergistic Effect of High Ionic Transfer Separator and Lithium-Boron Composite Material Anode.

The development of lithium (Li) metal batteries (LMBs) has been limited by problems, such as severe dendrite growth, drastic interfacial reactions, and large volume change. Herein, an LMB (8AP@LiB) combining agraphene oxide-poly(ethylene oxide) (PEO) functionalized polypropylene separator (8AP) with a lithium-boron (LiB) anode is designed to overcome these problems. Raman results demonstrate that the PEO chain on 8AP can influence the Li+ solvation structure in the electrolyte, resulting in Li+ homogeneous diffusion and Li+ deposition barrier reduction. 8AP exhibits good ionic conductivity (4.9 × 10-4 S cm-1), a high Li+ migration number (0.88), and a significant electrolyte uptake (293%). The 3D LiB skeleton can significantly reduce the anode volume changes and local current density during the charging/discharging process. Therefore, 8AP@LiB effectively regulates the Li+ flux and promotes the uniform Li deposition without dendrites. The Li||Li symmetrical cells of 8AP@LiB exhibit a high electrochemical stability of up to 1000 h at 1 mA cm-2 and 5 mAh cm-2. Importantly, the Li||LiFePO4 full cells of 8AP@LiB achieve an impressive 2000 cycles at 2C, while maintaining a high-capacity retention of 86%. The synergistic effect of the functionalized separator and LiB anode might provide a direction for the development of high-performance LMBs.

Near-Infrared BODIPY Photosensitizer for Modulating Mitochondrial Fusion Proteins and Inhibiting Choroidal Neovascularization.

Photosensitizers have emerged as cytotoxic reactive oxygen species (ROS) activators in photodynamic therapy (PDT), which induced cell apoptosis. As the major contributors to ROS and oxidative stress, mitochondria play an important role in cell apoptosis. Although there are many reports about near-infrared 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) as photosensitizers (PSs) for PDT, this kind of PS has rarely been used for treating mitochondrial function and choroidal neovascularization application at the same time. Herein, a novel near-infrared PS (BDP2) characterized by good water solubility, long wavelength excitation, and high ROS quantum yield has been made. Under near-infrared light irradiation, BDP2 would generate ROS with high yield, induce a mitochondrial morphology change, and trigger cell apoptosis by changing the fusion protein level. Deep investigation revealed that BDP2 can cause oxidative stress, break the balance between fusion and fission of mitochondrial dynamics protein through decreasing fusion protein MFN2 and OPA1 expression, and finally cause cell apoptosis. Due to these characteristics, the BDP2 PS was used to treat choroidal neovascularization in animal models and can inhibit neovascularization.

Building Sustainable Saturated Fatty Acid-Zinc Interfacial Layer toward Ultra-Stable Zinc Metal Anodes.

The commercialization pace of aqueous zinc batteries (AZBs) is seriously limited due to the uncontrolled dendrite growth and severe corrosion reaction of the zinc anode. Herein, a universal and extendable saturated fatty acid-zinc interfacial layer strategy for modulating the interfacial redox process of zinc toward ultrastable Zn metal anodes is proposed. The in situ complexing of saturated fatty acid-zinc interphases could construct an extremely thin zinc compound layer with continuously constructed zincophilic sites which kinetically regulates Zn nucleation and deposition behaviors. Furthermore, the multifunctional interfacial layer with internal hydrophobic carbon chains as a protective layer is efficient to exclude active water molecules from the surface and efficiently inhibit the surface corrosion of zinc. Consequently, the modified anode shows a long cycle life of over 4000 h at 5 mA cm-2. In addition, the assembled Zn||V2O5 full cells based on modified zinc anodes have excellent rate performance and long cycle stability.

Reactive Polymer as Artificial Solid Electrolyte Interface for Stable Lithium Metal Batteries.

Lithium (Li) metal anodes have the highest theoretical capacity and lowest electrochemical potential making them ideal for Li metal batteries (LMBs). However, Li dendrite formation on the anode impedes the proper discharge capacity and practical cycle life of LMBs, particularly in carbonate electrolytes. Herein, we developed a reactive alternative polymer named P(St-MaI) containing carboxylic acid and cyclic ether moieties which would in situ form artificial polymeric solid electrolyte interface (SEI) with Li. This SEI can accommodate volume changes and maintain good interfacial contact. The presence of carboxylic acid and cyclic ether pendant groups greatly contribute to the induction of uniform Li ion deposition. In addition, the presence of benzyl rings makes the polymer have a certain mechanical strength and plays a key role in inhibiting the growth of Li dendrites. As a result, the symmetric Li||Li cell with P(St-MaI)@Li layer can stably cycle for over 900 h under 1 mA cm-2 without polarization voltage increasing, while their Li||LiFePO4 full batteries maintain high capacity retention of 96 % after 930 cycles at 1C in carbonate electrolytes. The innovative strategy of artificial SEI is broadly applicable in designing new materials to inhibit Li dendrite growth on Li metal anodes.

Supramolecular Engineering Strategy to Construct BODIPY-Based White Light Emission Materials.

Two kinds of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyads BDP-OH containing 4-hydroxystyrene groups and BDP-PY bearing pyridinyl units were prepared. In addition, a naphthalene derivative NAP-PY modified by pyridinyl moieties substituent was made. The above three dyads could be used to construct white-light emission (WLE) material by a supramolecular engineering strategy due to their three primary colors of blue, green and red. The supramolecular correlations between the hydroxyl group of BDP-OH and the pyridinyl groups of NAP-PY and BDP-PY were confirmed by 1 H NMR titration, 2D NOESY and FTIR. A fluorescence monitor application was carried out based on the realization of WLE. This work might be useful for designing other WLE supramolecular systems and image display.

Chemical anchoring of SeS2 on a fluoro-substituted covalent organic framework as a high-performance cathode material.

In this work, a high-performance cathode material was achieved by using SeS2 post-functionalization of a fluorinated covalent organic framework (COF) through SNAr chemistry. The chemical and physical confinement of polysulfides and polyselenides combined with enhanced conductivity boosted its electrochemical performance as a cathode material for lithium-sulfur batteries (LSBs). COF-F-SeS2 delivered a discharge capacity of 1633 mA h g-1 at 0.1C, an excellent C-rate performance of 1163 mA h g-1 at 1C and favorable long cycle performance. This work provides a feasible strategy to overcome the bottlenecks of LSBs for high capacity, excellent C-rate performance and enhanced cycle performance.

Morphologies Transformation of BODIPY-Based Main Chain Supramolecular Polymers Amphiphiles: From Helical Nanowires to Nanosheets.

The aggregate morphologies of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) main chain supramolecular polymer amphiphiles (SPA) are tunable by a fine balance of different non-covalent interactions. When the BODIPY segments and sodium cholate are mixed in aqueous solution, they form SPA by electrostatic attraction and hydrogen-bonds. This SPA displays helical nanowires' morphology. After the third component dimeric ß-cyclodextrin (ß-CD-C) is added, the hydrogen bonds between the cholate are substituted by the host-guest interaction between cholate and ß-CD-C. Therefore, these SPA transform their aggregate morphologies into nanosheets' architecture. Therefore, a simple and effective way to regulate self-assembly by non-covalent forces is developed. This supramolecular method may provide an effective way to prepare various nanostructures in aqueous solution and show promising application in the future.

Photoresponsive, Water-Soluble Supramolecular Dendronized Polymer with Specific Lysosome-Targetable Bioimaging Application in Living Cells.

A novel photoresponsive, water-soluble supramolecular dendronized polymer (SDP) is prepared through a γ -cyclodextrin (γ -CD)-coumarin host-guest interaction. The supramolecular formation, photoresponsive process, and fluorescence properties are investigated by nuclear magnetic resonance (NMR) techniques and spectrometric measurements. Upon different-wavelength light irradiation, this supramolecular polymer undergoes noncovalent polymer and covalent polymer conversion due to coumarin cycloaddition and cleavage reactions. In addition, SDP for bioimaging in Michigan Cancer Foundation-7 (MCF-7) cells is performed and results show that the obtained SDP has good biocompatibility and is lysosome-targetable. This research enriches the field of supramolecular dendrimers and the photo-stimulation response material may have application prospects in organelle-targeting applications.

Highly Fluoro-Substituted Covalent Organic Framework and Its Application in Lithium-Sulfur Batteries.

We report the preparation of a highly fluoro-substituted crystalline covalent organic framework (COF) and its application as a cathode material in lithium-sulfur batteries (LSBs) upon sulfur confinement. A sulfur-functionalized COF with high sulfur content (60 wt %) was obtained through physisorption of elemental sulfur and subsequent SNAr reaction of sulfur with aromatic fluorides on the COF backbone. After such physical and chemical confinement of sulfur through a postfunctionalization approach, the COF material still shows some structural order, allowing us to investigate the structure-property relationship of such COF materials in LSB application. We compared the electrochemical performances of the two cathode materials prepared from a crystalline COF and its amorphous counterpart and studied the important factors that affect battery capacity, reaction kinetics, and cycling stability.

Synthesis and Morphology Evolution of Ultrahigh Content Nitrogen-Doped, Micropore-Dominated Carbon Materials as High-Performance Supercapacitors.

Nitrogen-doped carbon-based materials including nanocarbons, graphene, and conductive polymers are impressive as supercapacitor electrodes. However, ultrahigh nitrogen contents, micropore dominated, and morphology evolving carbonaceous electrodes have not achieved until now which are crucial for supercapacitor. Herein, we prepare a novel fumaronitrile (FUM) derived covalent triazine framework (FUM-CTF) and activated it by using KOH at different temperatures to obtain the corresponding carbon materials, which were used as supercapacitor electrode materials. Specially, the FUM-700 (sample activated at 700 °C) possesses an excellent specific capacitance of 400 F g-1 at a current density of 1 A g-1 and considerable energy density over 18 Wh kg-1 in KOH (6 m) aqueous electrolyte. In addition, this electrode shows 260 F g-1 at a current density of 20 A g-1 for charge/discharge operation. Furthermore, the FUM-700 electrode demonstrates extraordinary electrochemical stability with 97 % retention after 10 000 cycles at 10 A g-1 . Ultrahigh nitrogen contents, the microporous structure, and the inner nanoparticle morphology work in concert to contribute to the superior electrochemical performance of FUM-700. Our work might give some hints to help design other high-performance nitrogen-containing supercapacitor electrode materials.

BODIPY-based Carbonaceous Materials for High Performance Electrical Capacitive Energy Storage.

Incorporation of heteroatoms into carbon materials is crucial to tailor carbon materials' donor-acceptor properties and consequently tune their chemical and electrical performance. However, doping carbon materials with multi-heteroatoms (three or more, especially the light elements) has been rarely payed attention until now. In this work, we develop a porous organic polymer containing boron, nitrogen, fluorine elements and realize its corresponding carbonaceous materials by subsequent carbonation or KOH activation process. Electrochemical measurements results reveal that KOH activation sample (BPOP-700A) is endowed with excellent specific capacitance of 408 F g-1 in three-electrode system and an energy density over 19.2 Wh kg-1 in two-electrode system at aqueous electrolyte, which can be attributed to multi light elements (boron, nitrogen and trace fluorine) doping, favorable morphology and rational pore size distribution architecture. In addition, BPOP-700A displays well rate ability and outstanding cycle performance (10 A g-1 , 10 000 cycles, 95 % retention). Our work might give some hints in designing multi light element doping carbon materials in supercapacitor applications.

BODIPY-Based Conjugated Porous Polymer and Its Derived Porous Carbon for Lithium-Ion Storage.

Conjugated porous polymers (CPPs) possess great potential in the energy storage aspect. In this work, a boron-dipyrromethene (BODIPY)-conjugated porous polymer (CPP-1) is achieved by a traditional organic synthesis route. Following this, a carbonization process is employed to obtain the carbonized porous material (CPP-1-C). The two as-prepared samples, which are characterized by doping with heteroatoms and their porous structure, are able to shorten the lithium-ion pathways and improve the lithium-ion storage property. Then, CPP-1 and CPP-1-C are applied as anode materials in lithium-ion batteries. As expected, long-term cyclic performances at 0.1 and 1 A g-1 are achieved with maintaining the specific capacity at 273.2 mA h g-1 after 100 cycles at 0.1 A g-1 and 250.8 mA h g-1 after 300 cycles at 1 A g-1. The carbonized sample exhibits a better electrochemical performance with a reversible specific capacity of 675 mA h g-1 at 0.2 A g-1. Moreover, the capacity is still stabilized at 437 mA h g-1 after 500 cycles at 0.5 A g-1. These results demonstrate that BODIPY-based CPPs are capable of being exploited as promising candidates for electrode materials in the fields of energy storage and conversion.

Near-Infrared-Emissive Amphiphilic BODIPY Assemblies Manipulated by Charge-Transfer Interaction: From Nanofibers to Nanorods and Nanodisks.

A novel near-infrared (NIR)-emissive amphiphilic BODIPY derivative, BBDP, was successfully prepared and thoroughly characterized. The photophysical properties in various organic solvents and THF/H2 O mixtures with different fractions of water were investigated. BBDP self-assembled into nanofibers in a water environment owing to its amphiphilic properties. Through charge-transfer interactions, BBDP co-assembled with a perylene bisimide derivative, PBI, and a viologen derivative, MV, to generate two superamphiphiles. These two superamphiphiles were able to aggregate in water media at appropriate concentrations. The BBDP-PBI charge-transfer complex formed nanorods, whereas the BBDP-MV aggregates expressed a disk-like morphology. This research paves the way for us to manipulate the morphology of dye assemblies.

Cucurbit[8]uril-Based Water-Soluble Supramolecular Dendronized Polymer: Evidence from Single Polymer Chain Morphology and Force Spectroscopy.

A novel water-soluble supramolecular dendronized polymer (SDP) was prepared through cucurbit[8]uril (CB[8])-naphthalene host-guest interaction. The composition ratio between BDP and CB[8] of as-prepared luminescent supramolecular polymer was confirmed by 1H NMR technique and mass spectrometry. In addition, atomic force microscopy (AFM) images showing the polymer chain length up to 150 nm and height up to 1.75 nm unambiguously demonstrate the supramolecular polymer formation. This work might be useful for designing other main chain supramolecular dendronized polymers.

Amphiphilic BODIPY derivatives: the solvophobic effect on their photophysical properties and bioimaging in living cells.

Three novel amphiphilic BODIPY derivatives were prepared and their photophysical properties in THF/water mixtures with varying fractions of water were investigated. BDP-1 could self-assemble into different vesicle architectures in aqueous solution, while BDP-2 and BDP-3 with more hydrophilic abilities formed spherical and worm-like micelles. The BODIPY derivatives could be absorbed by HeLa cells and showed no apparent toxicity during the course of the test. In particular, unlike traditional amines or morpholinyl functionalized lysosome fluorescent probes, BDP-1 nanovesicles without targeted groups exhibit red emission and show effective lysosome biological imaging. Co-staining experiments with lysosome specific trackers further confirmed the disassembly of BDP-1 nanovesicles in lysosomes. This research provides a new avenue of using probes without targeting the structural unit to stain special organelles and shows potential applications in cell imaging fields.

A ferrocene-azobenzene derivative showing unprecedented phase transition and better solubility upon UV irradiation.

The ferrocene-aspartic acid-azobenzene derivative 1 showing an unprecedented photoinduced crystal-liquid phase transition at an elevated temperature and better solubility in organic solvents has been successfully reported.

BODIPY-based fluorescent thermometer as a lysosome-targetable probe: how the oligo(ethylene glycols) compete photoinduced electron transfer.

A novel BODIPY-based fluorescent thermometer, which shows a lysosome-targeting property, was successfully prepared. Due to the electron-donating ability of the oligo(ethylene glycols), the photoinduced electron-transfer pathway from morpholine to BODIPY dye is blocked. The fluorescence of the thermometer quenched by intramolecular rotation at room temperature was progressively enhanced during heating due to the increased microviscosity around the fluorophore.

BODIPY-based oligo(ethylene glycol) dendrons as fluorescence thermometers: when thermoresponsiveness meets intramolecular electron/charge transfer.

The temperature-dependent photophysical properties of a series of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives with different oligo(ethylene glycol) (OEG) dendrons were investigated. Weak fluorescence emission was observed for these BODIPY derivatives in dilute solution with low viscosity. BDP-G0 and BDP-G1-TEG exhibit a high quantum yield in viscous glycerol solutions, contrary to the moderate and little fluorescence enhancement for BDP-G1 and BDP-G2 under the same conditions. The photoinduced electron transfer (PET) may have quenched the fluorescence, as supported by calculation. Interestingly, the thermoresponsive BODIPY derivatives show heat-induced luminescence enhancement with a high signal-to-noise ratio and their emission maxima are dependent on the structures of branched tri(ethylene glycol) moieties. Finally, preliminary studies on the BODIPY derivatives as intracellular fluorescence indicators in living HeLa cells were carried out.

Chemoselective sequential "click" ligation using unsymmetrical bisazides.

Unsymmetrical bisazides containing chelating and nonchelating azido groups undergo chemoselective three-component copper(I)-catalyzed azide-alkyne conjugation reactions with two different alkyne molecules. In conjunction with the reactivity gap between aromatic and aliphatic alkynes, a bistriazole molecule can be generated with excellent regioselectivity by mixing two alkynes and a bisazide in a single reaction container. This method is applicable in aqueous solutions at neutral pH, which may lend utilities in bioconjugation applications.