Latest ArticlesHerein, the nanoscaled ATP-responsive upconversion metal-organic frameworks (UCMOFs) are aqueous-phase synthesized for co-delivery of therapeutic protein cytochrome c (Cyt c) and chemodrugs doxorubicin (DOX), achieving targeted combinational therapy of human cervical cancer. The UCMOFs are rationally fabricated by growing ZIF-90 on mesoporous silica-coated upconversion nanoparticles (UCNPs), in which the ZIF-90 layer attenuates the upconversion luminescence (UCL) and the rigid frameworks increase the stability of encapsulated proteins. Once the UCMOF@DOX/Cyt c are internalized into HeLa cells via specific recognition of sgc8 aptamers, the intracellular ATP triggers the dissolution of ZIF-90 into Zn2+, which facilitates not only the release of Cyt c and DOX but also the restoration of UCL for real-time monitoring of drug release. It has been demonstrated that the therapeutic efficacy is greatly improved by the combination of caspase-mediated apoptosis activated by Cyt c (protein therapeutics), DNA fragmentation induced by DOX (chemotherapy), and Zn2+-promoted generation of reactive oxygen species (ROS) (oxidative stress). Overall, our proposed multifunctional UCMOFs provide an effective platform for targeted combinational cancer therapy and in situ imaging, which hold great promise in biomedical and clinical applications.
A new micro-spherical conjugated macrocycle polymer (P[5]-TFB-CMP) was prepared by the condensation reaction between dihydrazide functionalized pillar[5]arene and 1, 3, 5-triformylbenzene under ambient conditions. P[5]-TFB-CMP exhibits large surface area with excellent thermal stability and has been used as additive to prepare composite PMMA film of photochromic naphthopyrans. The results showed that the addition of P[5]-TFB-CMP could dramatically accelerate the thermal fading rate of the photochromic composite film by up to 12 times. This is a new strategy to overcome the drawback of the matrix effect.
A palladium-catalyzed 2-alkylation of indoles with α-bromo esters is developed by employing a P, P=O ligand. The method features excellent regioselectivities, mild reaction conditions, and good functional group compatibility. The employment of the P, P=O ligand as well as 4 Å molecular sieves were crucial for the success of the transformation. Mechanistic studies indicate the reaction proceed through a radical pathway.
Over the last decade, numerous research efforts have been devoted to pillar [n]arenes since their debut. The popularity of pillararenes is a reflection of current research trend in supramolecular and macrocyclic chemistry in general. Among the vast applications (such as chemosensors, drug delivery, transmembrance channels, and separation) of pillararenes, their utilization in catalysis is a relatively less explored area. However, soaring attention has been paid by researchers in recent years and this field has seen gradual increasing publications. Therefore, in this review we will discuss progress in the emerging applications of pillararene architectures in catalysis based on various reaction genre including reduction, oxidation, coupling, decomposition and others. Furthermore, this review not only focuses on the pillararenes based current progress in catalysis, but also provides the signs for future development in this research field.
Pyridinium 1, 4-zwitterionic thiolates were applied to a formal [3 + 2] annulation reaction with modified activated alkynes, affording various tetrasubstituted thiophenes with aryl, alkenyl, alkyl or silyl group at the special position. The structural modification of alkyne substrates enabled the synthesis of diverse thiophenes to be achieved using the pyridinium 1, 4-zwitterionic thiolates as the sulfur-containing building blocks. This approach is metal-free and catalyst-free.
Carbon dots (CDs) are novel fluorescent nanomaterials with good water solubility, high resistance to photobleaching and low toxicity. While, there are few studies elaborate on the relationship among reaction conditions, properties and applications of CDs. In this study, a series of CDs are synthesized through a one-pot hydrothermal method, and different reaction conditions are carried out to study the influencing factors of CDs properties. As a result, with the increase of temperature and reaction time, the particle size and zeta potential of CDs increased, the maximum emission wavelength red-shifted and the fluorescence quantum yield (QY) improved. Among them, CD3006 has good water solubility and highest QY of 81.4%, which is beneficial for its applications in bioimaging and ion detection. CD3006 is almost nontoxic in cells at a concentration of 500 μg/mL. In addition, the positive charged CD3006 shows nuclear targeting potential because of its combination with DNA through electrostatic interaction in nucleus. The properties of CDs can be greatly enhanced by controlling reaction conditions, and it provides great application prospects.
In situ formation of composite micro-mesoporous dendritic fibrous nano-silica (DFNS) and Al-DFNS was prepared using a cetylpyridinium bromide (CPB) template synthetic system. Dealumination is induced by impregnation of zirconium with flux followed by a sulfuric acid treatment. This procedure results in a series of highly uniform nano-spheres, which exhibit stronger acid property than that of Al-MCM-41. In the selective alkylation of anthracene with tert‑amyl alcohol, SO42− modified Zr-contained dealuminated Al-DFNS (SZ-DeAl-DFNS) shows great catalytic activity and higher conversion (60.8%). The DFNS samples were characterized with XRD, SEM, TEM, NH3-TPD and other techniques. The results reveal that DFNSs consist of center-radial micro-mesopores and that the acid contribution of SZ-DeAl-DFNS is much broader, as compared with amorphous aluminosilicate
Palladium-catalyzed oxidative formal [4 + 1] annulation of pyridine-substituted acrylonitriles toward divergent fused N-heterocycles synthesis is reported. The heterodifunctionalization reaction with Cu(OAc)2 and urea as the nitrogen source accesses to nitrile-substituted pyrazolo[1, 5-a]pyridines in moderate to good yields, while the homodifunctionalization reaction with FeBr3 leads to synthesis of nitrile-substituted indolizines in excellent yields.
The development of ultra-sensitive methods for detecting anions is limited by their low charge to radius ratios, microenvironment sensitivity, and pH sensitivity. In this paper, a magnetic sensor is devised that exploits the controllable and selective coordination that occurs between a magnetic graphene quantum dot (GQD) and fluoride anion (F–). The sensor is used to measure the change in relaxation time of aqueous solutions of magnetic GQDs in the presence of F‒ using ultra-low-field (118 µT) nuclear magnetic resonance relaxometry. The method was optimized to produce a limit of detection of 10 nmol/L and then applied to quantitatively detect F– in domestic water samples. More importantly, the key factors responsible for the change in relaxation time of the magnetic GQDs in the presence of F‒ are revealed to be the selective coordination that occurs between the GQDs and F‒ as well as the localized polarization of the water protons. This striking finding is not only significant for the development of other magnetic probes for sensing anions but also has important ramifications for the design of contrast agents with enhanced relaxivity for use in magnetic resonance imaging.
Carbon dots (CDs) with fluorescence (FL) and room-temperature phosphorescence (RTP) optical properties have attracted dramatically growing interest in anti-counterfeiting application. Herein, color-tunable and stable FL and ultralong RTP (to naked eyes ~14 s) are successfully achieved in CDs system. Encoding information and patterns fabricated by directly screen-printing method are invisible to eyes under natural light. Interestingly, clear and multicolor patterns with tunable FL and RTP emissions are identified under the 365 nm, 395 nm and 465 nm excitation and removal of them, indicating potential application of carbon dots with different FL and RTP outputs in the high-level photonic anti-counterfeiting field.
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