Latest ArticlesFluorescent supramolecular nucleoside-based organogels or hydrogels have attracted increasing attention owing to their tunable stability, drug delivery, tissue engineering, and inherent biocompatibility for applications in designing sensors. As the temperature of a constant TPE-Octa-dU gelator at MGC as low as 0.2 wt% was increased with gel to sol transition, a progressive decrease in the fluorescence intensity was observed. 1H NMR study in ethanol-d6/H2O revealed the existence of intermolecular hydrogen-bond interaction between uridine nucleobase and triazole moieties. Based on these experiments, thus organogels induced by hydrogen bonding can promote an aggregation-induced emission (AIE) of TPE moiety. Thermoreversible gelation properties have been investigated systematically, including AIE-shapemorphing architecture owing to their unique solid-liquid interface and easy processability. At the same line, the related TPE-EdU derivative which was synthesized from 5-ethynyl-2'-deoxyuridine does not deliver organogels or hydrogels, and under similar circumstances TPE moiety of TPE-EdU does not efficiently exhibit AIE phenomenon either.
A purely organic D-π-A-π-D type emitter showing thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) was designed and synthesized by utilizing the benzophenone as an acceptor and the N-phenyl-2-napthylamine as a donor moiety. It exhibits considerable TADF character in doped PMMA film and room temperature phosphorescence with a long lifetime of 74 ms at 466 nm in solid state. The devices with the configuration of ITO/Mo2O3 (4 nm)/mCP (30 nm)/mCP: x wt% NP2BP/TmTyPB (60 nm)/LiF (1.5 nm)/Al (100 nm) were prepared by vacuum evaporation to explore their electroluminescent performance. Interestingly, the non-doped device has obtained near-white emission with a fluorescence emission peak at 475 nm and a phosphorescence emission peak at 563 nm having the CIE coordinate of (0.23, 0.32) and the maximum external quantum efficiency of 1.09%.
With excellent color purity (full-width half maximum (FWHM) < 40 nm) and high quantum yield, multi-resonance (MR) molecules can harvest both singlet and triplet excitons for highly efficient narrowband organic light-emitting diodes (OLEDs) owing to their thermally activated delayed fluorescence (TADF) nature. However, the highly rigid molecular skeleton with the oppositely positioned boron and nitrogen in generating MR effects results in the intrinsic difficulties in the solution-processing of MR-OLEDs. Here, we demonstrate a facile strategy to increase the solubility, enhance the efficiencies and modulate emission color of MR-TADF molecules by extending aromatic rings and introducing tert-butyls into the MR backbone. Two MR-TADF emitters with smaller singlet-triplet splitting energies (ΔEST) and larger oscillator strengths were prepared conveniently, and the solution-processed MR-OLEDs were fabricated for the first time, exhibiting efficient bluish-green electroluminescence with narrow FWHM of 32 nm and external quantum efficiency of 16.3%, which are even comparable to the state-of-the-art performances of the vacuum-evaporated devices. These results prove the feasibility of designing efficient solution-processible MR molecules, offering important clues in developing high-performance solution-processed MR-OLEDs with high efficiency and color purity.
Benzo-21-crown-7 (B21C7) is one of the most important crown ethers, which not only shows excellent physicochemical properties but also exhibits promising binding capability with dialkylammonium salts. In this paper, we designed and synthesized a fixed-tetraphenylethylene (FTPE) motif bridged ditopic benzo-21-crown-7 molecule (H). The fixed tetraphenylethylene motif endows H with aggregation induced emission (AIE) property. In the presence of a ditopic dialkylammonium salt guest molecule (G), a fluorescent supramolecular polymer with golden luminescent property could be fabricated. This B21C7-based host-guest supramolecular polymer with golden fluorescence may have potential application in dynamic luminescent materials.
The design of supramolecular systems with efficient singlet oxygen generation has attracted considerable interests. Herein, an AIE-based singlet oxygen generation system with chemiluminescence properties is reported in aqueous media based on supramolecular host-guest assembly between a water-soluble pillar[5]arene (WP5) and an AIE photosensitizer (TPEDM). The formed supramolecular nanoparticles exhibit significant singlet oxygen generation ability as well as enhanced fluorescence. In addition, by introducing catalase, this H2O2-responsive supramolecular system shows increased 1O2 generation efficiency compared with the blank nanoparticles. An efficient chemiluminescence system can also be achieved by entrapping an energy donor adamantane derivative (AMPPD). Moreover, the present system can function as nanoreactors to perform the photooxidation of dopamine to form polydopamine with visible light irradiation. This work provides a new strategy for the construction of 1O2 generation system based on supramolecular nanomaterials, which has potential applications in the fields such as chemiluminescence imaging and controlled photocatalysis.
Fluorescent sensing for specific detection of berberine is an important issue in view of its potential jeopardization to food safety and human health, but remains less investigated. To the best of our knowledge, there is no fluorescence turn-on and ratiometric sensors available for specific detection of berberine. In this study, calix[4]carbazole (3) has been synthesized and its property of recognizing berberine has been evaluated by UV–vis, fluorescence, NMR, DLS and TEM techniques. The results show that 3 selectively recognizes berberine among the tested drugs and detects it with turn-on and ratiometric fluorescence due to their co-assembly nature. Moreover, 3 is not only low toxic and can reduce toxicity of berberine to human normal liver L02 cell, but also can release berberine to tumor HepG2 cells at acid micro-environment. It therefore holds a great potential for further exploration
Helix structures at atomic/molecular level have not been found in self-assembled peptide sequence with less than three residues. As β-sheet supramolecular secondary structures have been discovered in solid-state amino acids, we here report the conjugation of simple N-terminal aryl protecting group could give rise to helical supramolecular secondary structures in solid-state, which determines the optical activities of the adjacent aryl groups. The carboxylic acid-involved asymmetric H-bonds in N-terminal aryl amino acids induce the emergence of super-helical structures of amino acid residues and aryl groups. In most cases, supramolecular tilted chirality of aryl groups is opposite to that of amino acid sequences, of which handedness and helical pitch are determined by the H-bond modalities. Determining correlation between supramolecular tilted chirality of aryl segments and their chiroptical activities is firstly unveiled, which was verified by the computational results based on density functional theory. Most aryl amino acids self-assembled by nanoprecipitation method via crystallization induced self-assembly into rigid one-dimensional microstructures with ultra-high Young's modulus. This study reveals the generic existence of chiral supramolecular structures in aggregated amino acid derivatives and gives an in-depth investigation into the structural-property relationships, which could guide the rational design and screening of chiroptical supramolecular materials.
An interlocked M4L8 coordination cage was synthesized by coordination-driven self-assembly of palladium(Ⅱ) ions with aromatic amide bidentate ligands. The reaction of the ligand and the metal at 2:1 ratio led to the monomeric M2L4 cage as the kinetic product, while the thermodynamic product M4L8 cage was obtained by prolongating the reaction. This conversion and the interlocked structure was clearly revealed by using 1H NMR, mass spectrometry and X-ray crystallography. The driving force of interlocking was mainly attributed to the interactions (hydrogen bonding, aromatic stacking and electrostatic interaction) arising from the aptitude of flexibility of the amide ligand.
Studies on the synthesis of antifungal and anticancer natural product, pseudolaric acid B, have led to the enantioselective synthesis of di-epi-trans-fused [5–7]-bicyclic core skeleton. The synthesis was achieved in 10 linear steps, which features the Sharpless asymmetric epoxidation, cyanide-opening reaction of epoxide, and intramolecular [5+2] cycloaddition reaction as the key transformations. The stereochemistry was determined by the X-ray crystallographic analysis.
The recent Ir/Pd co-catalyzed photo carboxylation of aromatic halides with CO2 has shown high efficiency and excellent functional group tolerance for preparing aromatic carboxylic acids and esters. With the aid of density functional theory (DFT) calculations, the carboxylation starts with two parallel steps, i.e., oxidative addition of aromatic halides on Pd0 and reductive quenching of the photocatalyst Ir(ppy)2(dtbpy)+ with amine. Thereafter, a successive oxidation of PdⅡ with the amine radical (generated by the reaction of cationic radical amine and Cs2CO3) and IrⅡ species occurs to generate Pd0, from which the carboxylation occurs easily via a coordination, Pd-C insertion step. The release of the carboxylate product then regenerates the catalyst.
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