Latest ArticlesA visible-light-induced spirocyclizative hydroarylation via reductive dearomatization of a series of non-activated arenes including 2-phenyl indoles and naphthalene derivatives under mild conditions is described. An intriguing chemoselective dearomative hydroarylation of 2-phenyl indoles is presented. This dearomative hydroarylation protocol rapidly delivers valuable spirocycles with carbon−carbon double bonds from readily accessible aromatic precursors in a single step.
The synthesis, structure, and properties of pyrene-based conformationally adaptive macrocycles are described. This new type of conformationally adaptive macrocycle was constructed through Perkin reaction, followed by imidization. By changing the condensation partner as the linking unit, a family of conjugated macrocycles with different sizes of the cavity was synthesized, which provide a simple and modular synthetic strategy towards the conformationally adaptive macrocycles. Furthermore, the macrocycles provide two well-defined conformations through flipping pyrene subunit, which were unambiguously determined by single-crystal X-ray diffraction analysis. The conformational interconversion barrier was determined by density functional theory (DFT) calculations. This new macrocycle also demonstrated unique properties, such as vapochromic behavior and aggregation emission enhancement effect. Furthermore, we have also investigated the effect of the linker on the shape and photophysical properties of the resulting macrocyclic products.
Catalytic hydrodeoxygenation (HDO) is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons. Herein, an efficient bimetallic catalyst Pt1Ni4/MgO was prepared and applied in the HDO of dibenzofuran (DBF). High yield (95%) of the desired product bicyclohexane (BCH) was achieved at 240 ℃ and 1.2 MPa of H2. Superior catalytic performance could be ascribed to the "relay catalysis" of Pt sites and Ni sites, and the reaction pathway is proposed as well. Scale-up experiment and recyclability test were also performed, which demonstrated the recyclability and promising potential application of Pt1Ni4/MgO.
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.
Room temperature phosphorescent (RTP) materials have a variety of applications ranging from bio-imaging, optoelectronic devices to information security protection. However, the preparation procedures for these materials are always tedious and time-consuming. Here, we report a micro-wave approach to prepare RTP carbon dots (CDs) in only 8 min. The micro-wave promoted the carbon and boron bond formation using natural compounds glucose and boric acids. This result has been confirmed using TEM, FTIR, XPS and XRD measurements. The C-B hetero atomized material presented a long afterglow property. With the irradiation with UV light, we observed an eight-second RTP by naked eyes after the lamp was turned off, and the phosphorescence lifetime was 487 ms. This excellent performance was mainly due to the formation of B-C bonds that promoted the intersystem crossings (ISC) and non-radiation transition of triplet states. Moreover, the glass state of the materials also helped to stabilize the triplet states of B-CDs and made its non-irradiation inactivated, which resulted in the characteristics of yellow green RTP. These results have demonstrated that micro-wave is a convenient and effective strategy to make hetero atomized RTP material, providing new possibilities for their industrial productions.
Star-shaped small molecules have attracted great attention for organic solar cells (OSCs) because they have three-dimensional charge-transport characteristics, strong light absorption capacities and easily tunable energy levels. Herein, three- and four-armed star-shaped small molecule donors, namely BDT-3Th and BDT-4Th, respectively, have been successfully designed and synthesized, which used benzodithiophene (BDT) as the central unit. The two star-shaped intermediates (2a and 2b) could be simultaneously obtained by one-step of Suzuki coupling, and 1, 2-dimethoxyethane played a key role in the Suzuki coupling. Both of them have excellent thermal stability, good solubility and broad absorption. Four-armed BDT-4Th shows a slightly higher extinction coefficient, a deeper HOMO energy level and an obviously better phase separation morphology when blended with Y6 than three-armed BDT-3Th. As a result, increased power conversion efficiency (PCE) of 5.83% is obtained in the BDT-4Th: Y6-based OSC devices, which is obviously higher than that of the BDT-3Th: Y6-based devices (PCE = 3.78%). To the best of our knowledge, this is the highest PCE among the BDT-based star-shaped donors-based OSCs. This result provides an effective strategy to obtain star-shaped small molecule donor materials for high efficient organic solar cells.
Two amphiphilic TPE E/Z isomers with aggregation induced emission (AIE) property have been synthesized and characterized. The logarithmic fluorescent intensity of the two molecules was in positive relationship with logarithmic viscosity of liquid. To note, the Z-TPE isomer exhibited more sensitivity in the viscosity of liquid sensing in comparison with the corresponding E-TPE counterpart (around 1.80 folds). Furthermore, two molecules could be used as fluorescent sensors for mechanical properties (viscosity and storage modulus) of hydrogel as well. In addition, two sensors displayed low cytotoxicity in normal tissue cell line (L929) within the concentration range of 2-10 μmol/L. These results potentially promised their applications as fluorescent sensors for mechanical properties in the fields of biological and biomedical.
Five hybrid tetrapeptides, each consisting a central dipeptide segment of α-amino acid residues flanked by two aromatic γ-amino acid residues, are found to fold into well-defined β-hairpin conformations as shown by NMR, computational study, and X-ray structures. The turn loop of this β-hairpin motif accommodates different two-residue α-amino acid sequences from the highly flexible Gly-Gly, to the more restricted d-Pro-Gly. The presence of α-amino acid side chains enhances the stabilities of the β-hairpins with the exception of d-Pro-Gly-which results in destabilization. Based on this hairpin/turn motif, a variety of different dipeptide sequences of α-amino acids which rarely occur in β-turns can be introduced and presented as two-residue loops.
Electronic tuning by para substitutions was explored to achieve a highly active manganese N-heterocyclic carbene pincer complex for the selective electrocatalytic reduction of CO2 to CO. [MnCNCOMe]BF4 (L2-Mn) bearing an electron-donating group (-OMe) showed high activity with 63×catalytic current enhancement, average Faradaic efficiency of 104%, and a TOFmax value of 26, 127 s-1, which is 127 times higher than that of unsubstituted [MnCNCH]Br (L1-Mn) reported previously. In contrast, the electron-withdrawing group (-COOMe) in [MnCNCCOOMe]PF6 (L3-Mn) inhibited the electrocatalytic activity. Ambient Brønstic acid, however, suppressed the activity of L2-Mn probably due to the protonation of the -OMe group. These findings indicate a potential electronic tuning strategy to improved manganese N-heterocyclic carbene catalysts for CO2 reduction.
Earth abundant metals are much less expensive, promising, valuable metals and could be served as catalysts for the borrowing hydrogen reaction, dehydrogenation and heterocycles synthesis, instead of noble metals. The uniformly dispersed zinc composites were designed, synthesized and carefully characterized by means of XPS, EDS, TEM and XRD. The resulting zinc composite showed good catalytic activity for the N-alkylation of amines with amines, ketones with alcohols in water under base-free conditions, while unsaturated carbonyl compounds could also be synthesized by tuning the reaction conditions. Importantly, it was the first time to realize the synthesis of 2-aryl-1H-benzo[d]imidazole derivatives by using this zinc composite under green conditions. Meanwhile, this zinc catalyst could be easily recovered and reused for at least five times.
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