Latest ArticlesFragrances are widely used in cosmetics, apparel and detergents. However, the rapid evaporation of the aroma shortens the useful life of the aromatic product. Therefore, improving the fragrance retention time of aromatic products and prolonging the service life of aromatic products are the key scientific problems that need to be solved in current aromatic products. In this study, zwitterionic comb-like lipid polymers were synthesized to encapsulate the fragrance molecule linalool. The results showed that the zwitterionic comb lipid molecules were capable of encapsulating more linalool than linear lipid molecules. At the same time, the zwitterionic comb-like lipid molecules also limited the slow release rate of the aroma, thereby increasing the fragrance retention time of the nano-fragrance.
Water-soluble thermoresponsive polymers present either upper critical solution temperature (UCST) or lower critical solution temperature (LCST) depending on the location of their miscibility range with water at high temperatures or at low temperatures. Compared with LCST polymers, the water-soluble UCST polymers are still less explored until now. In this work three copolymers of P(AAm-co-GAA) were synthesized by copolymerizing two acrylamide monomers, acrylamide (AAm) and acrylamide functionalized with natural glycyrrhetinic acid (GAA), using reversible addition-fragmentation chain transfer (RAFT) polymerization. These copolymers exhibited the typical UCST thermoresponsive behavior, and their phase transition temperatures could be easily tuned to around 37 ℃ for potential biological applications. Moreover, the UCST of P(AAm-co-GAA) can be adjusted not only by the content of glycyrrhetinic acid (GA) and polymer concentrations, but also by the host-guest interactions between GA and cyclodextrins (β- and γ-CD). The suitable value of UCST and the biocompatible nature of GA and CDs may endow these copolymers with practical applications in biomedical chemistry
Metal organic frameworks (MOFs) are a kind of promising materials in many applications, while the fast and controllable synthesis of MOFs is still challenging. Here, taking HKUST-1 as illustration, a micro-plasma electrochemistry (MIPEC) strategy was developed to accelerate the synthesis process of MOFs with micro-plasma acting as cathode. Treating the HKUST-1 precursor solution with micro-plasma cathode could not only transfer the electrons into the solution leading to the deprotonation effect, but also generate radical species to trigger and accelerate the nucleation and growth of MOFs at the plasma-liquid interface. Thus, uniform and nanosize MOFs could be prepared within minutes. The obtained MOFs show similar excellent uranium adsorption properties compared with those obtained by other method, with a highly adsorption capability of uranium with 550 mg/g in minutes. The novel MIPEC strategy developed in this work provides an alternative for controllable synthesis of MOFs, and especially has potential application in accelerating traditional organic synthesis.
A cascade carbonylative ring expansion and [2 + 2]/[4 + 2] cycloaddition of strained 1-iminylphosphirane complexes with aryl allenes were reported. The carbonylative ring expansion of 1-iminylphosphirane complexes provides an azaphosphacyclohexone complex intermediate with a C＝P double bond. The following [2 + 2] or dearomatic [4 + 2] cycloaddition of this intermediate with allenes is modulated by the aryl substituents on the imino carbon. The regioselective [2 + 2] cycloaddition with 1, 1-diarylallene provides an entry to bicyclo[4.2.0]octan-4-one skeletons featuring a four-membered phosphacyclobu-tane moiety. While dearomatic [4 + 2] cycloaddition was preferred with less aromatic naphthalene and yielded octahydrochrysene skeleton containing heteroatoms.
Metal-nitrogen-carbon materials (M-N-C) are non-noble-metal-based alternatives to platinum-based catalysts and have attracted tremendous attention due to their low-cost, high abundance, and efficient catalytic performance towards the oxygen reduction reaction (ORR). Among them, Fe-based materials show remarkable ORR activity, but they are limited by low selectivity and low stability. To address these issues, herein, we have synthesized FeCu-based M-N-C catalysts, inspired by the bimetal center of cytochrome c oxidase (CcO). In acidic media, the selectivity was notably improved compared with Fe-based materials, with peroxide yields less than 1.2% (< 1/3 of the hydrogen peroxide yields of Fe-N-C catalysts). In addition to Cu-N-C catalysts which can catalytically reduce hydrogen peroxide, the reduction current of hydrogen peroxide using FeCu-N-C-20 exceeded that of Fe-N-C by about 6% when the potential was greater than 0.4 V. Furthermore, FeCu-based M-N-C catalysts suffered from only a 15 mV attenuation in their half-wave potentials after 10, 000 cycles of accelerated degradation tests (ADT), while there was a 30 mV negative shift for Fe-N-C. Therefore, we propose that the H2O2 released from Fe-Nx sites or N-doped carbon sites would be reduced by adjacent Cu-Nx sites, resulting in low H2O2 yields and high stability.
Transition metal phosphide (TMP) based electrocatalysts possessing special crystal and electronic structures attract broad attention in the field of electrocatalysis. Immense effort is made to optimize TMP catalysts aiming to satisfy the electrochemical catalysis performance. In this work, an environmentally friendly in situ green phosphating strategy and spatial limiting effect of the RuCo precursor is employed to fabricate the ruthenium nanoclusters anchored on cobalt phosphide hollow microspheres (Ru NCs/Co2P HMs). The obtained Ru NCs/Co2P HMs electrocatalysts exhibit high hydrogen evolution reaction (HER) activity at wide pH ranges, which require an overpotential of 77 mV to achieve the current density of 10 mA/cm2 in 0.5 mol/L H2SO4 and 118 mV in 1.0 mol/L KOH. Besides, the multifunctional Ru NCs/Co2P HMs exhibit good oxygen evolution reaction (OER) activity with an overpotential of 197 mV to reach the current density of 10 mA/cm2 in 0.5 mol/L H2SO4, which is below that of the commercial RuO2 electrocatalyst (248 mV). A two-electrode electrolyzer is assembled as well, in acid electrolyte, it achieves a current density of 10 mA/cm2 at a voltage of 1.53 V, which is superior to that of the benchmark of precious metal-based electrolyzer (1.58 V).
An eco-friendly, sustainable and practical method for the efficient preparation of 5-organylselanyl uracils through the electrochemical selenylation of uracils and diorganyl diselenides at room temperature under oxidant- and external electrolyte-free conditions was developed.
Curcurbit[n]uril (Q[n])-based supramolecular frameworks (QSFs) constructed from the outer surface interaction of Q[n]s (OSIQ) have the characteristic of simplicity, diversity and modulability. Their simplicity is reflected in their simple composition and preparation methods used for QSFs. The diversity of supramolecular organic frameworks (SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs, as well as the variety of structural directing agents and basic building blocks used to prepare QSFs. The modulability is reflected by the controllable channel size in the QSFs, which can be adjusted using different sizes of Q[n]s. In this work, the first reported cucurbituril Q[6] was selected as the basic building block and three Q[6]-based supramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl4]2- respectively. The OSIQs are the main driving forces for the formation of these frameworks. This study shows the diversity of the QSFs.
Star shape bridged pillar[5]arene trimer (C3-PLT) based on benzene-1,3,5-tricarboxamide (BTAs) was successfully synthesized, which exhibited outstanding guest responsive morphology transition properties. The morphology tuning studies was efficiently achieved with the addition of competitive guest molecules G1 and G2 by various self-assembly mechanisms. C3-PLT itself displays nanofiber morphology through H-type π-π stacking, and this nanofiber morphology can be completely transformed into spherical vesicles by host-guest interaction G1, while upon addition of G2 into C3-PLT by means of "exo-wall" electron-transfer interactions, sheet superstructures can be observed. SEM, 1H NMR, DOSY, fluorescence spectroscopy, and viscosity have verified the formation of supramolecular polymers and morphological transitions between C3-PLT with both guests.
The demand for injectable dermal filler has undergone significant growth with the rapid development of the beauty industry. Poly(lactic acid) (PLA) as a benefit of excellent biocompatibility and long-term promotion of collagen regeneration has been favored as a commonly used filler. However, the effects of chirality and particle size of PLA on the efficacy of dermal filler have not been studied. In this study, we prepared three kinds of microspheres (MSs) consisting of poly(D-lactic acid) (PDLA MS), poly(L-lactic acid) (PLLA MS), or meso-PLA (PDLLA MS) at 5, 10 and 20 μm to reveal the different biological functions as dermal filler. Following intradermal injection into guinea pig, it was found that PLLA MS induced the slightest inflammation, and the level of pro-inflammatory cytokine IL-1β induced by PLLA MS is only 0.3 or 0.7-fold of that induced by PDLA or PDLLA MS, respectively. More importantly, PLLA MS significantly stimulated the regeneration of collagen, which was 1.4 or 1.1 times higher than those stimulated by PDLA MS or PDLLA MS, respectively. The size of PLA MSs did not affect the levels of inflammation and collagen regeneration. The results confirmed the superiority of PLLA as a dermal filler.
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