Latest ArticlesThe selective oxidative esterification of aldehydes with alcohols to the corresponding esters has been one of the hot spots in scientific research and industrial synthesis. However, the application of precious metal catalytic systems is limited by their complicated synthetic steps and high cost. Thus a highly efficient, green, recyclable selective synthesis method of esters catalyzed by polyoxovanadate (POV)-based molecular catalysts has been developed in this paper. The results show that supramolecular interaction between POV and 1,3-dibenzylimidazolium bromide (Act2Im) can efficiently convert alcohols and aldehydes to the corresponding esters in high yield under much milder conditions. Mechanistic insight is also provided based on the control experiments, single crystal X-ray diffraction and cyclic voltammetry studies.
We report here the synthesis and characterization of two new members of the M2E12 family of endohedral Zintl clusters, [Fe2Sn4Bi8]3– and [Cr2Sb12]3–, both of which contain open-shell metal dimers encapsulated inside a triple-decker cluster of main-group atoms. The 75-electron [Fe2Sn4Bi8]3– cluster has a D4h-symmetric structure, while [Cr2Sb12]3–, despite having the same 75-electron count, is strongly distorted to a geometry that resembles a CrSb8 crown capped by a CrSb4 unit. The structural differences between the two are driven by the increasing availability of 3d electron density in the earlier transition metal, which leads, ultimately, to different electronic configurations in the two clusters. The trends precisely mirror those observed in the ME10 and ME12 families containing a single transition metal ion.
Concise chemistry leads to a family of heptanuclear CoⅡ-clusters, [Co7(N3)12(CH3CN)12] [Y2(NO3)4(piv)4]·2CH3CN (DC1) (pivH = pivalic acid), [Co7(N3)12(CH3CN)10(NO3)0.4 (Cl)1.6]·4CH3CN (DC2) and [Co7(N3)12(CH3CN)10(NO3)2]·4CH3CN (DC3), in which the metal ions are exclusively bridged by end-on azido ligands to stabilize a beautiful disk-like topology. The resulting clusters exhibit interesting structural transformations and thermodynamically-distinct steady states verified by theoretical calculations. Magnetic studies reveal the first observation of zero-field SMM behaviour in disk-like heptanuclear CoⅡ complexes.
Electron-deficient viologens are widely used as ligands or structure-directing agents (SDAs) to synthesize crystalline X-ray induced photochromic materials. Here, a new rational strategy of anion-directed folding a flexible cation (H2imb)2+ ((H2imb)2+ = di-protonated 2,3-bis(imidazolin-2-yl)-2,3-dimethylbutane) has been developed. Electron-donating Cl− and (ZnCl4)2− are used to direct folding a flexible electron-deficient (H2imb)2+ cation. Three complexes (H2imb)(NO3)2 (1), (H2imb)Cl2·H2O (2), and (H2imb)ZnCl4 (3) have been synthesized in which (H2imb)2+ crystallize in an anti-conformation, 88.8°-gauche, and 51.8°-gauche, respectively. In contrary to X-ray silent complex 1, X-ray induced photochromism has been achieved in both complex 2 and 3. An intermolecular charge-transfer mechanism has been elucidated and the anion directed folding of (H2imb)2+ has been validated to be critical to yield colored long-lived charge-separated states.
Metal-organic frameworks (MOFs) functionalized with open metal sites (OMSs) have received widespread attention in various applications due to their fascinating electronic properties and unique interactions with guest molecules. However, rational tailoring of the coordination environment of metal nodes during the synthesis of MOFs remains a great challenge due to their tendency of saturated coordination with linkers. Herein, we reported the construction of three new MOFs featuring unsaturated Cu(Ⅱ) sites, namely [Cu(HCOO)(pzta)]n (HL-1), {[Cu(PTA)0.5(pzta)(H2O)]·2H2O}n (HL-2) and [Cu(NA)0.5(pzta)]n (HL-3) (Hpzta = 3-pyrazinyl-1,2,4-triazole; PTA = terephthalic acid; NA = 1,4-naphthalene dicarboxylic acid), based on the mixed-linker strategy via specific selection of versatile Hpzta ligand and carboxylate ligands. Remarkably, the obtained MOFs exhibited excellent activity and good recyclability for the catalytic reduction of nitroaromatics under mild conditions (25 ℃ and 1 atm). In particular, the complete conversion of 4-nitrophenol (4-NP) took only 30 s on HL-2, reaching a record-high TOF value compared with previously reported metal catalysts. The combined experimental and theoretical studies on HL-2 revealed that the open Cu site with positive-charged nature could improve the adsorption and subsequent electron transport between the substrates, and was responsible for the outstanding performance. This work shined lights on the further enhancement of performance for MOFs through rational OMSs construction.
Recently, the utilization of nonsteroidal anti-inflammatory drugs (NSAIDs) to sensitize cisplatin (CDDP) has gained substantial traction in the treatment of ovarian cancer (OC). However, even widely employed NSAIDs such as celecoxib and naproxen carry an elevated risk of cardiovascular events, notably thrombosis. Furthermore, the diminished sensitivity to CDDP therapy in OC is multifactorial, rendering the application of NSAIDs only partially effective due to their cyclooxygenase-2 (COX-2) inhibiting mechanism. Hence, in this study, reactive oxygen species (ROS)-responsive composite nano-hydrangeas loaded with the Chinese medicine small molecule allicin and platinum(Ⅳ) prodrug (DTP@AP NPs) were prepared to achieve comprehensive chemosensitization. On one front, allicin achieved COX-2 blocking therapy, encompassing the inhibition of proliferation, angiogenesis and endothelial mesenchymal transition (EMT), thereby mitigating the adverse impacts of CDDP chemotherapy. Simultaneously, synergistic chemosensitization was achieved from multifaceted mechanisms by decreasing CDDP inactivation, damaging mitochondria and inhibiting DNA repair. In essence, these findings provided an optimized approach for synergizing CDDP with COX-2 inhibitors, offering a promising avenue for enhancing OC treatment outcomes.
Under the guidance of the approach which integrates molecular networking, MolNetEnhancer and Network Annotation Propagation (NAP), daphnaltaicanoids A and B (1 and 2) with unprecedented 9-oxa-tetracyclo[6.6.1.02,6.08,13]pentadecane and tetracyclo[5.3.0.12,5.24,11]tridecane central frameworks were isolated from Daphne altaica Pall., representing two types of unparalleled meroterpenoid cores. Their structures were elucidated by extensive spectroscopic analysis, nuclear magnetic resonance (NMR) calculations, DP4+ analysis and electronic circular dichroism (ECD) calculations. The plausible biosynthetic pathways for 1 and 2 were postulated. Biologically, 2 exerted potent neuroprotective activities which were superior to trolox at 12.5 and 25 µmol/L. Moreover, 1 and 2 exhibited more noticeable acetylcholinesterase inhibitory activities than donepezil. Molecular docking simulations were performed to explore the intermolecular interaction of compounds 1 and 2 with acetylcholinesterase. The bioactivity evaluation results highlight the prospects of 1 and 2 as a novel category of neurological agents.
Recently, a novel 2-electron oxygen reduction reaction (ORR) based electro-oxidation (EO) system was developed, which utilizes a H2O2 generation cathode instead of H2 evolution cathode. A Ti-based Ni-Sb co-doped SnO2 (Ti/NATO) anode was selected for efficient degradation of refractory organics and O3 production. The synergistic reaction of O3/H2O2 further accelerated the generation of hydroxyl radicals (•OH) in the ORR-EO system. However, the catalytic activity and long-term effectiveness of the Ti/NATO anode limited the large-scale application of the ORR-EO process. In this study, a blue TiO2 nanotube array (blue-TiO2-NTA) inter-layer was introduced into the fabrication process between the Ti substrate and NATO catalyst layer. Compared to the Ti/NATO anode, the Ti/blue-TiO2-NTA/NATO anode achieved higher efficiency of organic removal and O3 generation. Additionally, the accelerated lifetime of the Ti/blue-TiO2-NTA/NATO anode was increased by 7 times compared to the Ti/NATO anode. When combined with CNTs-C/PTFE air cathode in ORR-EO system, all anodic oxidation and O3/H2O2 processes achieved higher •OH production. Over 92% of TOC in leachate bio-effluent was effectively eliminated with a relatively low energy cost of 45 kWh/t.
Traditional therapies such as surgery and endocrine therapy no longer meet the clinical needs in prostate cancer treatment, and more effective treatments are urgently required. Recent studies have reported that targeted inhibition of the transcription factor cyclin dependent kinase 7 (CDK7) could effectively suppress prostate cancer progression. However, the toxicity of CDK7 inhibitors such as THZ1 is the main limitation of the clinical application. In this work, we synthesized Cys8E (C8E) nanoparticles (NPs) loaded with THZ1 (C8E@THZ1), a novel GSH-targeting and stimuli-responsive nano-delivery platform, and investigated its anti-tumor potential and biosafety properties. In vitro, C8E@THZ1 potently inhibited the proliferation and promoted the apoptosis of prostate cancer cells. On tumor-bearing mice, C8E@THZ1 inhibited tumors by up to 85%, while the damage of THZ1 to liver function was effectively avoided. These results confirmed that inhibition of CDK7 can effectively block the progression of prostate cancer, and that Cys8E NPs is a highly prospective delivery platform to promote the clinical application of CDK7 inhibitors.
Bioprinting is emerging as an advanced tool in tissue engineering. However, there is still a lack of bioinks able to form hydrogels with desirable bioactivities that support positive cell behaviors. In this study, modified plasma proteins capable of forming hydrogels with multiple biological functions are developed as bioinks for digital light processing (DLP) printing. The Plasma-MA (BM) was synthesized via a one-pot method through the reaction between the fresh frozen plasma and methacrylic anhydride. The methacrylated levels were observed to influence the physical properties of BM hydrogels including mechanical properties, swelling, and degradation. The photo-crosslinked BM hydrogels can sustainedly release vascular endothelial growth factor (VEGF) and exhibit positive biological effects on cell adhesion and proliferation, and cell functionality such as tube formation of human umbilical vein endothelial cells (HUVECs), and neurite elongation of rat pheochromocytoma cells (PC12). Meanwhile, BM hydrogels can also induce cell infiltration, modulate immune response, and promote angiogenesis in vivo. Moreover, the plasma bioinks can be used to fabricate customized scaffolds with complex structures through a DLP printing process. These findings implicate that the modified plasma with growth factor release is a promising candidate for bioprinting in autologous and personalized tissue engineering.
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