Many highly ordered structures with smart functions are generated by self-assembly with stimuli responsiveness. Despite that electron microscopes enable us to directly observe the end products, it is ...hard to visualize the initial step and the kinetic stimuli-responsive behavior of self-assembly. Here, we report the design and synthesis of stereogenic amphiphiles, namely, (Z)-TPE-OEG and (E)-TPE-OEG, with aggregation-induced emission (AIE) characteristics from the hydrophobic tetraphenylethene core and thermoresponsive behavior from the hydrophilic oligoethylene glycol monomethyl ether chain. The two isomers can be easily isolated by high-performance liquid chromatography and characterized by 2D NMR spectroscopy. While (Z)-TPE-OEG self-assembles into vesicles, its (E)-cousin forms micelles in water. The initial step of their self-assembly processes can be visualized based on AIE characteristics, with a sensitivity much higher than the method based on transmittance measurement. The entrapment and release capabilities of the (Z)-stereogenic amphiphile are demonstrated by employing pyrene as a guest. The thermoresponsive behavior of the (Z)-amphiphile results in its continuous phase transition from microscopic self-assembly to macroscopic aggregation, which is successfully visualized in situ by confocal laser scanning microscopy accompanied by the AIE technique. Such a kinetic process shows different stages according to the microscopic visualization, and these stages have never been monitored through roughly observing the appearance of precipitates. It is anticipated that this study can deepen the understanding of the self-assembly processes for better monitoring and controlling them in different systems.
Catalytically inactive Zn2+ is incorporated into cobalt hydroxide to synthesize hierarchical ZnCo-layered double hydroxide nanosheet networks supported on carbon fiber (ZnCo-LDH/CF). The ...incorporation of Zn2+ is revealed to endow ZnCo-LDH/CF with significantly superior performance in the aspects of the activity and selectivity for methanol electrooxidation to formic acid and the boosting effect for cathodic hydrogen production compared with the counterpart without Zn2+. Density functional theory (DFT) calculation reveals that the incorporation of nonactive Zn2+ can increase the density of states near the Fermi level of LDH (i.e., elevate electrical conductivity to form favorable charge transportation during electrocatalysis) and promote the adsorption and subsequent cleavage of methanol, thus leading to the enhanced methanol electrooxidation performance.
Efficient photoisomerization of chromophores is important in living systems, and structural constraints of protein pocket on chromophores are the probable reason for moving their dynamic reaction ...equilibrium forward. On the other hand, photochemical reaction to switch a molecule from one isomer to the other with different geometry and property in a high yield will continue to play a vital role in the synthetic chemistry and material science. Because of the important role of efficient photoisomerization, a biomimetic approach for “seeing” and controlling the photoisomerization is developed by using the technology of aggregation-induced emission (AIE) with supramolecular chemistry. It is revealed that a (Z)-isomer of a 2-ureido-41H-pyrimidinone-containing tetraphenylethene (TPE-UPy) can be photoisomerized into supramolecular polymer form of its (E)-counterpart in chloroform in a high reaction yield of 68.1%. The yield is further enhanced to 100% in THF as aggregates of supramolecular polymers of (E)-TPE-UPy are formed, which completely inhibits the reverse photoreaction to form (Z)-TPE-UPy. In chloroform with organic acid, a mixture of equal amounts of (E)- and (Z)-isomers was obtained due to the disruption of the formation of intermolecular hydrogen bonds. The AIE characteristics of the isomers allow us to directly “see” the “turn-on” photoisomerization process by distinct fluorescence color changes, and the photoisomerization observed here may enable the development of a promising generation of optical power limiting materials.
Indium-based materials (e.g., In
2
O
3
) are a class of promising non-noble metal-based catalysts for electroreduction of carbon dioxide (CO
2
). However, competitive hydrogen reduction reaction ...(HER) on indium-based catalysts hampers CO
2
reduction reaction (CO
2
RR) process. We herein tune the interfacial microenvironment of In
2
O
3
through chemical graft of alkyl phosphoric acid molecules using a facile solution-processed strategy for the first time, which is distinguished from other researches that tailor intrinsic activity of In
2
O
3
themselves. The surface functionalization of alkyl phosphoric acids over In
2
O
3
is demonstrated to remarkably boost CO
2
conversion. For example, octadecylphosphonic acid modified In
2
O
3
exhibits Faraday efficiency for H
2
(
FE
H
2
) of as low as 6.6% and FE
HCOOH
of 86.5% at −0.67 V vs. RHE, which are far superior to parent In
2
O
3
counterparts (
FE
H
2
of 24.0% and FE
HCOOH
of 63.1%). Moreover, the enhancing effect of alkyl phosphoric acid functionalization is found to be closely related to the length of alkyl chains. By virtue of comprehensive experimental characterizations and molecular dynamics simulations, it is revealed that the modification of alkyl phosphoric acids significantly alters the interface microenvironment of the electrocatalyst, which changes the electrocatalyst surface from hydrophilic and aerophobic to hydrophobic and aerophilic. In this case, the water molecules are pushed away and more CO
2
molecules are trapped, increasing local CO
2
concentration at In
2
O
3
active sites, thus leading to the significantly enhanced CO
2
RR and suppressed HER. This work highlights the importance of regulating the interfacial microenvironment of inorganic catalysts by molecular surface functionalization as a means for promoting the electrochemical performance in electrosynthesis and beyond.
Type-I photosensitizers (PSs) can generate free radical anions with a broad diffusion range and powerful damage effect, rendering them highly desirable in various areas. However, it still remains a ...recognized challenge to develop pure Type-I PSs due to the inefficiency in producing oxygen radical anions through the collision of PSs with nearby substrates. In addition, regulating the generation of oxygen radical anions is also of great importance toward the control of photosensitizer (PS) activities on demand. Herein, a piperazine-based cationic Type-I PS (PPE-DPI) that exhibits efficient intersystem crossing and subsequently captures oxygen molecules through binding O
to the lone pair of nitrogen in piperazine is reported. The close spatial vicinity between O
and PPE-DPI strongly promotes the electron transfer reaction, ensuring the exclusive superoxide radical (O
) generation via Type-I process. Particularly, PPE-DPI with cationic pyridine groups is able to associate with cucurbit7uril (CB7) through host-guest interactions. Thus, supramolecular assembly and disassembly are easily utilized to realize switchable O
generation. This switchable Type-I PS is successfully employed in photodynamic antibacterial control.
Synthetic polymerization and supramolecular polymerization with sequence control are far from an easy task. Herein, a narcissistic self-sorting supramolecular polymer is prepared with a sequence of ...(−AA–BB−) n by using cucurbit8uril (CB8)-based ternary complexes as supramolecular monomers, which are spontaneously formed from heteroditopic AB-type guest and CB8. Supramolecular polymerization and the structural changes at each stage of polymerization have been successfully demonstrated by NMR, UV–vis, and fluorescence spectra. The self-sorting starts from the second step of polymerization after the formation of different ternary complexes as supra-monomers. The dynamic supramolecular interactions and the thermodynamic stability of the host–guest complexes are found to be the crucial factors to drive the sequence control of the supramolecular polymers. Furthermore, the water-soluble supramolecular polymer is red-emissive and can serve as a fluorescent sensor to detect morphine in artificial urine with considerable stability, sensitivity, and accuracy. And it can also distinguish heroin and morphine, two kinds of opioids with similar structures.
Attrition scrubbing was used to remediate lead contaminated-site soil, and the main purpose was to remove fine particles and lead contaminants from the surface of sand. The optimal parameters of ...attrition scrubbing were determined by orthogonal experiment, and three soil samples with different lead concentration were subjected to attrition scrubbing experiments. The results showed that the optimal scrubbing parameters were: a solid ratio of 70% dry matter, a temperature of 25 degrees C, an attrition time of 30 min, and an attrition speed of 1200 r x min(-1). Before attrition scrubbing, the screening and analysis of soil showed that in all three soil samples, lead was mainly enriched on sand and fine particles, and the distribution of lead was highly correlated to the organic matter. After attrition scrubbing, the washing efficiency of the original state lead contaminated sand soil in triplicates was 67.61%, 31.71% and 41.01%, respectively, which indicates that attrition scrubbing can remove part of the fine s
In article number 1803144, Huijun Zhao, Wenjun Zhang, and co‐workers synthesize ultrathin δ‐FeOOH nanosheets with rich Fe‐vacancies grown on Ni foam, and propose an iron‐vacancy‐based catalyst ...activation principle to induce water‐splitting bifunctionality. The formation of the second neighboring Fe to the Fe vacancies in the δ‐FeOOH nanosheets can create active centers for both the hydrogen and the oxygen evolution reaction.
In article number 1901545, Wenjun Zhang and co‐workers synthesize a novel nanoflower‐like electrocatalyst comprising of few‐layer nitrogen‐doped graphene encapsulated nickel copper alloy on porous ...graphic carbon framework by a facile and scalable method, and it exhibits high activity and excellent stability for hydrogen evolution.
Excitation energy transfer (EET) as a fundamental photophysical process is well-explored for developing functional materials with tunable photophysical properties. Compared to traditional ...fluorophores, aggregation-induced emission luminogens (AIEgens) exhibit unique advantages for building EET systems, especially serving as energy donors, due to their outstanding photophysical properties such as bright fluorescence in aggregation state, broad absorption and emission spectra, large Stokes shift, and high photobleaching resistance. In addition, the photophysical properties of AIEgens can be modulated by energy transfer for improved luminescence performance. Therefore, a variety of EET systems based on AIEgens have been constructed and their applications in different areas have been explored. In this review, we summarize recent progress in the design strategy of AIE-based energy transfer systems for light-harvesting, fluorescent probes and theranostic systems, with an emphasis on design strategies to achieve desirable properties. The limitations, challenges and future opportunities of AIE–EET systems are briefly outlined.
Graphic Abstract
Design strategies and applications (light-harvesting, fluorescent probe and theranostics) of AIEgen-based excitation energy systems are discussed in this review.
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