Latest ArticlesAcidification of paper-based relics is a common problem, leading to their degradation and eventual loss. Paper deacidification is highly dependent on a limited variety of alkaline materials, and the development of new materials that are safe, efficient and easy-to-prepare is highly demanded to ensure a high level of safety and effective protection of paper-based relic. This study proposes the introduction of layered double hydroxide (LDH) and its calcined product, mixed metal oxide (layered double oxide (LDO)), as innovative protective materials for the deacidification of paper with varying levels of acidity. The results demonstrate that treatment with Mg-Al LDH/LDO can effectively modify the pH of acidic paper (e.g., pH ~ 4.0–6.4) to a neutral or weakly basic state, maintaining this desirable pH range even under long-term accelerated aging condition. Remarkably, LDH proves to be well-suited for the protection of slightly acidified paper (e.g., pH > 5.5), while LDO serves as an especially option for the deacidification of severely acidified paper (e.g., pH ≤ 5.5). During aqueous deacidification, due to the memory effect of the LDH-based materials, LDO is converted to rehydrated LDH, which creates a mild and appropriate alkaline retention in the paper, avoiding damage caused by strong alkalinity such as cellulose degradation and pigment fading during subsequent long-term natural preservation of the paper. Furthermore, Mg-Al LDH/LDO materials also exhibit flame-retardant and bacteriostatic properties. This opens up opportunities for the safe, efficient and multifunctional protection of acidified paper-based relics.
Owing to the spread of COVID-19, it is difficult to ignore the existence and importance of antimicrobial polymers (AMPs) because most protective appliances are made of polymers. Generally, bacteria prefer hydrophilic compounds, while fungi prefer hydrophobic ones. In recent decades, AMPs have made significant strides due to the versatile design of the functional groups or units for hydrophilic, hydrophobic, or amphiphilic performances. This review summarizes the advances of AMPs itself from the perspective of their wettability. Moreover, this study aims to clarify how the functional groups determine the interaction between the polymer and microorganisms directly affects the antimicrobial efficacy of the designed polymers. Based on the advances, the challenges and outlooks of AMPs from the perspective of wettability are systematically discussed to build a bridge between the structural design of AMPs and the requirements of practical applications.
Thermoelectric (TE) materials enable effective and direct energy conversions between heat and electricity, displaying wide applications including waste/low-grade heat harvesting, local cooling, sensing and wearable electronics. Among the recently-developed organic and composite TE materials, poly(3,4-ethylenedioxythiophene) (PEDOT) is perhaps the most successful and frequently reported type. Herein, we aim to review the recent advances of the synthesis, mechanism and applications of PEDOT-based TE composites. First, the research background and the history of TE materials are briefly introduced. Next, the synthesis and TE performance of PEDOT-based composites are summarized according to the sequence of films, hydrogels/aerogels and fibers/yarns. Then, the mechanism, structure and property are elucidated. After that, the recent development and its applications of power generation and sensing are highlighted. Finally, we provide an outlook on the prospects and the challenges of PEDOT-based TE composites.
Biomass absorbing materials have received increasing attention for electromagnetic wave (EMW) absorption field absorbing materials due to its low density and high dielectric loss. However, the biomass EMW absorbing materials often suffer from the insufficient magnetic loss and impedance matching. In this work, a facile ZIF-8/ZIF-67-derived biomass composites (CoZnO@BPC) was prepared for high-performance EMW absorption based on multi-component micro, nano structures metal particles and xanthoce sorbifolia bunge shells-derived biomass porous carbon (BPC). The dielectric loss and/or magnetic loss abilities of CoZnO@BPC composites were adjusted by changing the mass ratio of Zn2+ to Co2+ ions. Under the filled amount of 20 wt%, CoZnO@BPC exhibited excellent EMW absorption with the minimum reflection loss (RL) at 15.84 GHz is -50.2 dB, and the matching thickness is only 1.7 mm. By adjusting the ZIFs mass ratio, the effective absorption bandwidth (EAB) can be up to 5.92 GHz (from 12.08 GHz to 18 GHz), and the matching thickness is only 1.9 mm. The results provide a new insight for the economical and efficient preparation of lightweight and advanced microwave absorbing materials.
An efficient and scalable electrochemical asymmetric protocol with metal-free catalysts and even without additional oxidants for the cross-dehydrogenative coupling reaction (CDC) of two C(sp3)-H bonds is reported. A series of aldehydes including natural products and various substrates containing C(sp3)-H bonds including xanthenes, acridines, cycloheptatrienes and even diarylmethane have been shown to undergo asymmetric CDC to afford a series of carbon-carbon bond coupling products with up to 94% yield and 98% ee. Mechanistic studies such as radical clock experiment suggest that the reaction proceeds via nucleophilic attack by enamine under electrochemical conditions.
A simple and additive-free protocol has been developed for the preparation of β-keto phosphorodithioates through the three-component reaction of easily available sulfoxonium ylides, P4S10, and alcohols. The present geminal hydro-phosphorodithiolation reaction was performed at room temperature to construct a series of β-keto phosphorodithioates in the absence of any metal reagents, bases, or additives.
Stimuli-triggered release and alleviating resistance of iridium(Ⅲ)-based drugs at tumor sites remains challengeable for clinical hepatoma therapy. Herein, a doxorubicin@iridium-transferrin (DOX@Ir-TF) nanovesicle was synthesized by carboxylated-transferrin (TF) and doxorubicin-loaded amphiphilic iridium-amino with quaternary ammonium (QA) groups and disulfide bonds. The QA groups enhanced photophysical properties and broadened production capacity of photoinduced-reactive oxygen species (ROS), while the disulfide-bridged bonds regulated oxidative stress levels through reacting with glutathione (GSH); simultaneously, modification of TF improved recognition and endocytosis of the nanovesicle for tumor cells. Based on in-vitro results, a controlled-release behavior of DOX upon a dual-responsiveness of GSH and near-infrared ray (NIR) irradiation was presented, along with high-efficiency generation of ROS. After an intravenous injection, the nanovesicle was targeted at tumor sites, realizing TF-navigated photoacoustic imaging guidance and synergistic chemotherapy-photodynamic therapy under NIR/GSH stimulations. Overall, newly-synthesized DOX@Ir-TF nanovesicle provided a potential in subcutaneous hepatocellular carcinoma therapy due to integrations of targeting delivery, dual-stimuli responsive release, synergistic therapy strategy, and real-time monitoring.
Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery. The development of synthetic strategies for highly efficient preparation of enones thereby receives intense attention, in particular through the transition metal-catalyzed coupling reactions. Here, we describe a carbene-catalyzed cross dehydrogenative coupling (CDC) reaction that enables effective assembly of simple aldehydes and alkenes to afford a diverse set of enone derivatives. Mechanistically, the in situ generated aryl radical is pivotal to "activate" the alkene by forming an allyl radical through intermolecular hydrogen atom transfer (HAT) pathway and thus forging the carbon-carbon bond formation with aldehyde as the acyl synthon. Notably, our method represents the first example on the enone synthesis through coupling of "non-functionalized" aldehydes and alkenes as coupling partners, and offers a distinct organocatalytic pathway to the transition metal-catalyzed coupling transformations.
Multicharged supramolecular assemblies based on luminescent macrocycle play an important role in extending their optical properties and functions. Herein, we reported macrocyclic supramolecular assemblies based on luminescent terphen[3]arene sulfate (TP[3]AS) and tetraphenylethylene pyridinium (TPE-4Py) through electrostatic interactions, host-guest encapsulation and π-π stacking interactions. Förster resonance energy transfer (FRET) process from TP[3]AS to TPE-4Py was achieved with the energy transfer efficiency of 99.9%, accompanied by TPE-4Py fluorescence emission bathochromic shifted of 15 nm and enhanced by 1.68 times in PBS solution. In contrast, other non-luminescent sulfato-β-cyclodextrin and sulfobutylether-β-cyclodextrin only can enhance the fluorescence intensity of TPE-4Py without bathochromic shift. Due to the strong fluorescence and good stability of TPE-4Py@TP[3]AS, it can be used for optical imaging in living cells, which provided an effective approach for the construction of assembling-confined luminescent biomaterials.
Semiconductor-molecule surface-enhanced Raman scattering (SERS), especially the stronger interfacial charge transfer process (ICTP), represents a frontier in the field of SERS with spectral reproducibility and unparalleled selectivity. Herein, through a laser microfabrication method in situ, the free-standing, super hydrophilic and vacancy-rich TiO2-x/Ti is successfully synthesized. Using blue TiOx/Ti (B-TiOx/Ti) as pre-concentrated substrate, a nanomolar-level limit of detection of 12 nmol/L at 1385 cm–1, is confirmed using crystal violet (CV) bacteriostat as a model under 532 nm excitation. Furthermore, the results demonstrate that the SERS enhancement mechanism is via the moderate adulteration of oxygen vacancy, which leads to a narrow value of band gap and increases the ICTP of substrate to molecules. Using a hand-held extractor assembled with B-TiOx/Ti microfiber, the operando analysis of mixtures distributed information excited in different parts of Asian carp is facilely achieved. This work guides the controlled synthesis of vacancy-rich TiO2-x/Ti nanostructure and its application in ultrasensitive extraction-SERS detection. It also provides the direction for the rapid and operando transmission of biological information with temporal and spatial concentration distribution in human tissues by highly sensitized materials.
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