Latest ArticlesGeneration of multi-substituted pyrroles is accomplished through an unexpected iron(Ⅱ)-promoted reaction of N-arylprop-2-yn-1-imines with water. This transformation proceeds smoothly with excellent chemoselectivity and regioselectivity. A stoichiometric amount of Fe(OTf)2 is necessary for the successful conversion. A Lewis acid-promoted tandem reaction pathway is proposed.
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.
Both racemate and enantiomer of a novel double helix, binaphthylcyclooctaterthiophene (BN—COTh), which is a DNA-like molecule constructed by two single helices intertwined with each other via covalent bonds, have been synthesized with two building blocks, cycloocta-tetrathiophene (COTh) and cyclooctadinaphthyldithiophene (CONT) fused together via Negishi coupling reaction. Another homologue, dinaphthylcyclooctaterthiophene (DN-COTh) has been employed together as a model compound. Besides the synthetic work, BN—COTh and DN-COTh have been investigated by studying their crystal structures, spectroscopic behaviors, chiral resolution and chiral characteristics, including circular dichroism (CD) spectra and optical rotations. In addition, the novel crystal of enantiomer of (R, R, R)-BN—COTh has been explored. The enantiomer molecules packing along b-axis to form a larger and extended assembly packing due to intermolecular interactions between the enantiomer molecules and chloroform molecules in crystal.
In this communication, a new supramolecualr amphiphile was successfully constructed based on water soluble pillar[5]arene and a unique guest which contain a CO2 responsive tertiary amine unit and a UV responsive coumarin group. When guest molecule 1 dispersed in water, it self-assembled into sheet-like structures. Upon bubbling CO2, 1 transformed into 1H due to the tertiary amine unit was protonated, accompany the nano-sheets transformed into vesicles. Further irradiation of 1H with 365 nm light for 3 h, the coumarin group reacted with each other to form bola-type amphiphie 2H. In this case, vesicles collapsed and re-assembled into nano-tubes. However, when addition of WP5 into the solution of 1H, the vesicles transformed into micelles, this is due to the formation of supramolecular amphiphile WP5&1H. Upon irradiation of WP5&1H with 365 nm light for 3 h, nano-ribbons observed instead of micelles in the solution. Notably, nanotubes from 2H could also transform into nano-ribbons after adding WP5. The self-assembly process and the resultant assemblies were characterized by TEM, SEM, DLS, SAXS and NMR technologies. Due to both CO2 and light are pgreenq for living organisms, we anticipated our system can offer the possibilities in pon demandq drug absorption and release.
Multi-bond network (MBN) hydrogels contain hierarchical dynamic bonds with different bond association energy as energy dissipation units, enabling super-tough mechanical properties. In this work, we copolymerize a protonated 2-ureido-4[1H]-pyrimidone (UPy)-contained monomer with acrylic acid in HCl solution. After removing excess HCl, UPy motifs are deprotonated and from dimers, thus generating an UPy-contained MBN hydrogel. The obtained MBN hydrogels (75 wt% water content) exhibit super-tough mechanical properties (0.39 MPa to 2.51 MPa tensile strength), with tremendous amount of energy (1.68 MJ/m3 to 11.1 MJ/m3) dissipated by the dissociation of UPy dimers. The introduction of ionic bonds can further improve the mechanical properties. Moreover, owing to their dynamic nature, both UPy dimers and ionic bonds can re-associate after being dissociated, resulting in excellent self-recovery ability (around 90% recovery efficiency within only 1 h). The excellent self-recovery ability mainly originates from the re-association of UPy dimers based on the high dimerization constant of UPy motifs.
As a novel family of macrocyclic molecules, cucurbit[n]urils (CB[n]s) have emerged as promising building blocks of supramolecular nano drug delivery systems (SNDDS) in recent years. Direct encapsulation of amphiphilic guests by CB[6] and CB[7] can modulate their amphiphilicity, resulting in formation of supramolecular amphiphiles that self-assemble into supramolecular nanoparticles for drug delivery. Additionally, CB[n]'s host-guest chemistry on the surface of mesoporous nanoparticles makes CB[n] an ideal blocking agent to control drug release from delivery vehicles. These SNDDS possess intrinsic stimuli responsiveness towards external guest or host, which can further incorporate responsiveness to a variety of other stimuli including pH, thermal, redox, photo and enzyme, to realize multiple stimuli-responsive drug release. Moreover, the recent breakthrough in direct functionalization of CB[n]s has provided a feasible method for preparing superior CB[6] and CB[7] derivatives that can be employed to build multifunctional SNDDS with unoccupied macrocycles located on surface, which could be decorated with various functional "tags" through host-guest chemistry. In this review, we summarized the recent progress of CB[6] and CB[7] based SNDDS through formation of supramolecular amphiphiles, supramolecular nanovalves as well as supramolecularly tailorable surface, which we hope to further promote the development of CB[n]s family as building blocks for advanced SNDDS.
Two fluoride sulfates, K2Mn3(SO4)3F2·4H2O (I) and Rb2Mn3(SO4)3F2·2H2O (Π) are obtained by water solution method. Single-crystal X-ray diffraction analysis indicated that they crystallize in space groups of Cmc21. Their structures feature a pseudo-KTP structure consisting of interconnecting [Mn3(SO4)3F2(H2O)2]∞ layers, which are further packing along the a axis with alkali metal cations balancing the charges. The structure relationships between the two compounds are discussed. Second-harmonic generation measurements manifest that I and Π have similar second-harmonic generation responses of about 0.2 and 0.25 times that of KH2PO4.
A facile and metal-free visible-light-enabled three-component reaction of quinoxalin-2(1H)-ones, alkenes and CF3SO2Na has been developed under air at room temperature. This photocatalytic tandem reaction using 4CzIPN as the photocatalyst and air as the green oxidant, provides a mild and environmentally friendly approach to access a series of 3-trifluoroalkylated quinoxalin-2(1H)-ones.
A hierarchically structured MnOx-NiCo2O4 monolithic catalyst with rich phase interfaces was designed by a simple, eco-friendly and time-saving in-situ electro-deposition method. The abundance of active oxygen species due to this rich phase interfaces contributed to the excellent benzene combustion performance of MnOx-NiCo2O4-2:2 sample, oxidizing about 90% of benzene (T90) at 198 ℃ under 12000 h-1 gaseous hourly space velocity. This work shed new light on the design of excellent monolithic catalysts, which might pave the way for the industrialization of benzene combustion.
Series of azobenzene-bridged pillar[5]arene-based [3]rotaxanes with different alkyl chain length of guest molecules were constructed by threading-endcapping method with alkylenetriazole as axile and tetrahydrochromene as endcapping group. The encapsulation of pillar[5]arenes were proved by high-resolution mass, 1H NMR and NOESY spectra. The photo-responsive property were examined by irradiation of the synthesized [3]rotaxanes with 365 nm and blue light LED, which caused trans to cis and cis to trans isomerization, respectively. Irradiation of corresponding model guest compounds without pillar[5]arene encapsulation resulted in near completely trans to cis and cis to trans isomerization, indicating the existence of pillar[5]arenes is the determining factor for the comprised photo isomerization efficiency.
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