A novel fluorescent film was fabricated by doping the aggregates of hexaphenylsilole (HPS) into a chitosan film. It was demonstrated that the fluorescence emission of the film is stable, sensitive and highly selective to the presence of picric acid (PA). The detection limit for PA is about 2.1 Â 10 À8 mol/L. Introduction of 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), nitrobenzene (NB), phenol, benzene, toluene, methanol, ethanol, and zinc nitrate (Zn(NO 3 ) 2 ) had little effect upon the fluorescence emission of the film. The selectivity of the film was attributed to the specific electrostatic association effect of the protonated substrate film to picrate anion and the screening effect of the film to the interferents. The network structure of the substrate film is also favourable for the stabilization of the fluorescence emission of the hybrid film, by preventing the further aggregation of silole aggregates. Fluorescence lifetime measurements revealed that the quenching is static in nature. Furthermore, the quenching process is fully reversible. Considering the simplicity of the preparation and the outstanding performance of the hybrid film, it is anticipated that it could be developed into a real-life PA sensor.

Current treatments for chronic diabetic wounds remain unsatisfactory due to the lack of ideal wound dressings that can integrate matching mechanical strength, fast self‐healability, facile dressing change, and multiple therapeutic effects into one system. In this work, benefiting from the catechol groups and therapeutic effect of epigallocatechin‐3‐gallate (EGCG, green tea derivative), a smart hydrogel dressing can be conveniently obtained through copolymerization of the complex formed by EGCG and 3‐acrylamido phenylboronic acid (APBA) (the formation of boronate ester bond) and acrylamide. The resulting hydrogel features adequate mechanical properties, self‐healing capability, and tissue adhesiveness. Otherwise, the substantial release of EGCG can not only realize anti‐oxidation, antibacterial, anti‐inflammatory and proangiogenic effect, and modulation of macrophage polarization to accelerate wound healing, but also facilitate easy dressing change. This advanced hydrogel provides a facile and effective way for diabetic chronic wound management and may be extended for the therapy of other complicated wound healings.

Smart materials are highly desirable over the recent decade due to the growing demand of complicated nature. Stable stimuli-responsive smart materials exhibit widespread potential for applications in smart windows, sensors, separators, chemical valves, and release platforms but are rare. Despite being good candidates, viologen-based multifunctional smart materials are still a challenging task for chemists. To obtain such materials, the judicious strategy is to introduce polynuclear metal−carboxylate clusters as electron donors into a stable framework to increase chromic sensitivity. Toward this endeavor, we have synthesized a novel viologen-based polymer with a unique Anderson-like metal−carboxylate cluster, [Zn 7 (bpybc) 1), which is a particular 7-fold interpenetrated framework with a 3D pcu network in which bpybc ligand as the linker and Zn 7 O 30 C 12 as the second building unit (Zn 7 SBU) were used as 6-connected nodes. More importantly, it shows excellent chromic behavior in response to multiple external stimuli especially soft X-ray and UV dual light, temperature, electricity, and organic amines, which stand out in the viologenbased polymers. Interestingly, the coloration process of 1 from "core" to "edge" is observed upon heating at the appropriate temperature, which has not yet been found in other reported thermochromic materials. Of particular interest for 1 is the couple of quaternary stimuli-sensitive abilities because it simultaneously meets the following conditions: (i) the capability of withstanding high light, higher temperature, extreme pH, and other harsh conditions; and (ii) the high sensitivity to external stimuli keeping away from photodegradation, thermal relaxation, side reactions, and so on. To be noted, 1 has high thermal stability and chemical stability, which are excellent advantages as smart materials. To further develop possible practical utilization, 1 has been doped into the polymer matrixes to construct a hybrid film, which not only keeps the response to external stimuli but also significantly improves the repeatability of the photochromic process, indicating that a new smart device with multi-stimuli-responsive functions will emerge successively in the future.

Photosynthesis is ap rocess wherein the chromophores in plants and bacteria absorb light and convert it into chemical energy.T om imic this process,a ne missive poly(ethylene glycol)-decorated tetragonal prismatic platinum(II) cage was prepared and used as the donor molecule to construct al ight-harvesting system in water.E osin Yw as chosen as the acceptor because of its good spectral overlap with that of the metallacage,w hich is essential for the preparation of lightharvesting systems.S uchacombination showed enhanced catalytic activity in catalyzing the cross-coupling hydrogen evolution reaction, as compared with eosin Yalone.This study offers ap athway for using the output energy from the lightharvesting system to mimic the whole photosynthetic process.Photosynthesis, [1] as the primary source for the fuel on earth, is ap rocess by which living plants and bacteria absorb, capture,t ransfer, and store energy from the sun. In this process,the energy from sunlight is captured and funneled by adense array of chlorophyll molecules to the reaction center, and then converted into chemical energy. [2] So far, many artificial light-harvesting systems mimicking this process have been developed by using aF çster resonance energy-transfer (FRET) process,w ith the aim of developing clean and sustainable energy. [3][4][5] Among them, supramolecular systems [5] have received considerable attention not only because of their tunable and functionable molecular structures but also because the energy transfer between chlorophyll and protein in natural systems also relies on supramolecular selfassembly.F or example,Y ang et al. developed ah ighly efficient light-harvesting system based on the self-assembly of organic nanocrystals. [5b] Wang, Hu, and co-workers reported light-harvesting systems formed by water-soluble pillar[6]arene-based host-guest interactions. [5g] However, most of these systems just mimicked the FRET process of natural systems.T he use of the output energy for photocatalytic reactions has been rarely addressed. As natural photosynthetic systems also use the transferred energy for chemical reactions,artificial light-harvesting systems with the ability to catalyze chemical reactions for storing and releasing chemical energy are urgently needed.Metal-organic cages and metallacages [6] represent threedimensional cagelike structures formed by metal-coordination-driven self-assembly.W ith precisely controlled inner cavities,such fascinating structures have been widely studied in the past three decades for guest encapsulation, catalysis, and stabilizing reactive intermediates,e tc. [7] Recently,S tang et al. developed as eries of emissive metallacages [8] through the incorporation of tetraphenylethylene (TPE) derivatives as the building blocks.T hese metallacages exhibited aggregation-induced emission (AIE) properties [9] because of the restriction of molecular motions that decrease the nonradiative decay.Inartificial light-harvesting systems,thousands of donor molecules are generally used for asingle acceptor,...

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Two poly(pyrene-co-phenyleneethynylene)s of different compositions (PyPE-1 and PyPE-2) were synthesized and characterized. The two polymers had been casted, separately, onto glass plate surfaces to fabricate films (film 1, film 2) for sensing performance studies. It has been demonstrated that the fluorescence emissions of the two films are sensitive to the presence of 2,4,6-trinitrotoluene (TNT) in aqueous phase. Interestingly, TNT shows little effect upon the emission of the parent polymer, poly(phenyleneethynylene) (PPE). The difference was explained by considering (1) the π–π interaction between pyrene moieties contained in the copolymers and the analyte, TNT, molecules, and (2) more suitable matching of the LUMOs (lowest unoccupied molecular orbital) of the pyrene-containing conjugated polymers with that of TNT molecules. Further experiments demonstrated that the sensing is reversible and rarely encounters interference from commonly found compounds, including other nitroaromatics (NACs). Fluorescence lifetime measurements revealed that the quenching is static in nature. The smart performance of the films and the easiness of their preparation guarantee that the films may be developed into sensor devices for the supersensitive detection of TNT in groundwater or seawater.

It is quite challenging to realize fluorescence resonance energy transfer (FRET) between two chromophores with specific positions and directions. Herein, through the self-assembly of two carefully selected fluorescent ligands via metal-coordination interactions, we prepared two tetragonal prismatic platinum(II) cages with a reverse FRET process between their faces and pillars. Bearing different responses to external stimuli, these two emissive ligands are able to tune the FRET process, thus making the cages sensitive to solvents, pressure, and temperature. First, these cages could distinguish structurally similar alcohols such as n-butanol, t-butanol, and ibutanol. Furthermore, they showed decreased emission with bathochromic shifts under high pressure. Finally, they exhibited a remarkable ratiometric response to temperature over a wide range (223-353 K) with high sensitivity. For example, by plotting the ratio of the maximum emission (I 600 /I 480 ) of metallacage 4b against the temperature, the slope reaches 0.072, which is among the highest values for ratiometric fluorescent thermometers reported so far. This work not only offers a strategy to manipulate the FRET efficiency in emissive supramolecular coordination complexes but also paves the way for the future design and preparation of smart emissive materials with external stimuli responsiveness.

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are well-established therapeutics for gastrointestinal neoplasias, but complications after EMR/ESD, including bleeding and perforation, result in additional treatment morbidity and even threaten the lives of patients. Thus, designing biomaterials to treat gastric bleeding and wound healing after endoscopic treatment is highly desired and remains a challenge. Herein, a series of injectable pH-responsive self-healing adhesive hydrogels based on acryloyl-6-aminocaproic acid (AA) and AA-g-N-hydroxysuccinimide (AA-NHS) were developed, and their great potential as endoscopic sprayable bioadhesive materials to efficiently stop hemorrhage and promote the wound healing process was further demonstrated in a swine gastric hemorrhage/wound model. The hydrogels showed a suitable gelation time, an autonomous and efficient self-healing capacity, hemostatic properties, and good biocompatibility. With the introduction of AA-NHS as a micro-cross-linker, the hydrogels exhibited enhanced adhesive strength. A swine gastric hemorrhage in vivo model demonstrated that the hydrogels showed good hemostatic performance by stopping acute arterial bleeding and preventing delayed bleeding. A gastric wound model indicated that the hydrogels showed excellent treatment effects with significantly enhanced wound healing with type I collagen deposition, α-SMA expression, and blood vessel formation. These injectable self-healing adhesive hydrogels exhibited great potential to treat gastric wounds after endoscopic treatment.