Latest ArticlesOne-step assembly of organic-ligand modified Pd-Keggin-POMs has been rarely reported, so as for their applications in catalytic benzothiadiazole generation and derived cell-imaging probing. Herein, three Pd-Keggin-POMs (compounds 1–3) have been successfully synthesized via a one-step assembly strategy. Thus-obtained Pd-Keggin-POMs with well-defined structures and heterogeneous properties enable highly efficient catalytic benzothiadiazole generation. Specifically, compound 3 showed outstanding catalytic activities in Suzuki-Miyaura coupling reactions for the generation of benzothiadiazole derivatives (yields, 90%-97%) and was represented as one of the best catalysts reported to date. Consequently, the obtained benzothiadiazoles were used as the bio-probe for tracking lipid droplets in living-cells and exhibited large Stokes shifts (130 nm), low cytotoxicity and good targeting, which could be also applied to mark the distribution of LDs in living HeLa cells. Systematic investigations clearly decipher the functions of Pd-Keggin-POMs toward finding novel bio-probe materials, highlighting a new insight into the generation of sustainable materials in life-science.
A series of linear poly(ethylene oxide)-b-poly(4-vinylbenzyl chloride)-b-poly(4-tert-butylstyrene) (PEO113-b-PVBC130-b-PtBSx or E113V130Tx) triblock terpolymers with various lengths x (=20, 33, 66, 104, 215) of PtBS block were synthesized via a two-step reversible addition-fragmentation chain transfer (RAFT) polymerization. The E113V130T triblock terpolymers were non-crystalline because the PVBC and PtBS blocks strongly hindered the crystallization of PEO block. The effects of PtBS block length x on the phase structures of E113V130Tx triblock terpolymers were investigated by combined techniques of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). It was found that with increasing x from 20 to 215, the phase structure of E113V130Tx triblock terpolymers became more ordered and changed from disordered structure, hexagonally-packed cylinder (HEX), hexagonally perforated layer (HPL), to lamellar (LAM) phase structures. Temperature-variable SAXS measurements showed that the HEX, HPL and LAM phase structures obtained for E113V130T66, E113V130T104 and E113V130T215 by thermal annealing, respectively, were thermodynamically stable in the temperature range of 30–170 ℃.
The electrochemical CO2 reduction reaction (CO2ER) is an emerging process that involves utilizing CO2 to produce valuable chemicals and fuels by consuming excess electricity from renewable sources. Recently, Cu and Cu-based nanoparticles, as earth-abundant and economical metal sources, have been attracting significant interest. The chemical and physical properties of Cu-based nanoparticles are modified by different strategies, and CO2 can be converted into multicarbon products. Among various Cu-based nanoparticles, Cu-based metal-organic frameworks (MOFs) are gaining increasing interest in the field of catalysis because of their textural, topological, and electrocatalytic properties. In this minireview, we summarized and highlighted the main achievements in the research on Cu-based MOFs and their advantages in the CO2ER as electrocatalysts, supports, or precursors.
Increasing the charging cut-off potential of lithium cobalt oxide (LiCoO2, LCO) can effectively improve the energy density of the lithium-ion batteries, which are the mainstream energy storage devices used in 3C electronic products. However, the continuous decomposition of the electrolyte and dissolution of Co from the electrode will occur at high-potential operation, which deteriorate the performances of LCO. Here, a cathode-electrolyte interface (CEI) layer containing MgF2 is constructed to enhance the electrochemical stability of LCO at 4.6 V (vs. Li+/Li). The Mg2+ added to the cathode gradually releases into the electrolyte during cycling, which forms a stable MgF2-rich protective layer. In addition, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether (TTE) is added to the electrolyte acting as a F source to increase the content of MgF2 in the CEI layer. The MgF2-rich CEI layer effectively suppresses the decomposition of electrolyte components and the dissolution of Co of LCO, which makes the Li||LiCoO2 (Li||LCO) cell cycled stably at 3~4.6 V (vs. Li+/Li) in 200 cycles with a retention of 83.9%.
Suzuki coupling reactions between symmetrical monomers were conducted in various mesoporous silica nanoreactors grafted with palladium catalysts, enabling the selective formation of [12]cycloparaphenylene precursor with separate yield up to 25% in one-pot reactions, much higher than that in homogeneous reaction. The spatial nanoconfinement of the nanoreactors promotes the macrocyclization while limits the concomitant linear oligomer formation, offering more possibilities for the synthesis of macrocycles from symmetrical monomers in one-pot reaction.
MOF-based composites have aroused widespread concern due to their controllable morphology and pore characteristics. Nevertheless, the poor conductivity and volume expansion hinder its practical application in LIBs. Herein a classical structure HKUST-1, as the precursor, was used to fabricate quasi-Cu-MOF composite through a facile thermal decomposition strategy. The results showed that quasi-Cu-MOF composite had superior reversible specific capacity (627.5 mAh/g at 100 mA/g) and outstanding cycle stability (514.6 mAh/g at 500 mA/g after 400 cycles) as anodes for LIBs. The results demonstrated that the low-temperature calcination strategy played a significant role in morphology retaining during cycling and the derived copper framework play a crucial part in conductivity improvement. This work is helpful to the design of high-performance electrodes with advanced three-dimensional hierarchical structures.
Twenty-four novel neonicotinoid analogues with nitromethylene and five-membered aromatic heterocycles were designed and synthesized. All target molecular structures have been confirmed by analytical and spectral data. Some compounds exhibited notable insecticidal activities against aphid (Aphis medicaginis) and brown planthopper (Nilaparvata lugens). The aqueous stability test confirmed that the stabilities of those compounds were superior to the leading compound, and the photostability was even better than that of imidacloprid.
Organic-inorganic hybrid perovskites (OIHPs) materials with high phase transition temperature (Tp) have been widely studied in the field of molecular switches, solar energy and electric power. At present, the OIHPs with high Tp are generally constructed through molecular design, which can be applied to a wide temperature range. Here, three one-dimensional (1D) OIHPs [R-ClEQ]PbCl3 (Tp = 442 K), [R-ClEQ]PbBr3 (Tp= 499 K) and [R-ClEQ]PbI3 (Tp above m.p.) (R-ClEQ = (R)-N-chloroethyl-3-quinuclidinol) with different Tp are obtained by regulating the halogen-halogen interaction and hydrogen bonding in the system. Especially in [R-ClEQ]PbX3 (X = Cl, Br and I) crystal system, all the halogen bonds tend to form at approximately 180°angles and the strength of halogen bonding is found to be increased from 1.59 × 10–3 Hartree to 2.35 × 10–3 Hartree with increased atom number from Cl to I. The synergistic effect of halogen bonding and hydrogen bonding provide a useful strategy for the design OIHPs phase transition materials with high Tp.
Single atom catalysts (SACs) with atomically dispersed transition metals on nitrogen-doped carbon supports have recently emerged as highly active non-noble metal electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), showing great application potential in Zn-air batteries. However, because of the complex structure-performance relationships of carbon-based SACs in the oxygen electrocatalytic reactions, the contribution of different metal atoms to the catalytic activity of SACs in Zn-air batteries still remains ambiguous. In this study, SACs with atomically dispersed transition metals on nitrogen-doped graphene sheets (M-N@Gs, M = Co, Fe and Ni), featured with similar physicochemical properties and M-N@C configurations, are obtained. By comparing the on-set potentials and the maximum current, we observed that the ORR activity is in the order of Co-N@G > Fe-N@G > Ni-N@G, while the OER activity is in the order of Co-N@G > Ni-N@G > Fe-N@G. The Zn-air batteries with Co-N@G as the air cathode catalysts outperform those with the Fe-N@G and Ni-N@G. This is due to the accelerated charge transfer between Co-N@C active sites and the oxygen-containing reactants. This study could improve our understanding of the design of more efficient bifunctional electrocatalysts for Zn-air batteries at the atomic level.
It is greatly desired to develop novel gadolinium-based contrast agents (GBCAs) as improved platforms for magnetic resonance imaging (MRI). Herein, we report the syntheses of a series of nonionic cyclen-based GBCAs by precisely tuning carboxylate group on DO3A-pyridine scaffold. [Gd-DO3A-4cp] is isolated which adopts an octadentate coordination mode with a free carboxylate group at 4-position of pyridine. It shows the r1 relaxivity of 5.8 (mmol/L)−1 s-1 (3 T, 25 ℃), which is 75% higher than 3.3 (mmol/L)−1 s-1 of the clinic used [Gd-DOTA]. The possible mechanisms behind the enhanced relaxivity are investigated and proposed by structure-property relationship studies. After validation of low cytotoxicity and considerable kinetic inertness, in-vivo studies are further examined, demonstrating its good MRI performance, biodistribution as well as the way of excretion.