ISSN / EISSN : 2692-4560 / 2692-4560
Published by: Wiley-Blackwell (10.1002)
Total articles ≅ 95
Latest articles in this journal
A functional fabric with hierarchical structure consisting of basalt fibre fabric as a substrate and polyvinyl alcohol as a coating was developed, aiming at providing a low cost and high-performance way to separate highly emulsified oil in water. The coating functioned as a hydrophilic gate for the penetration of water in the emulsion, whereas the micro-channels formed in the fabric offered capillary force for the continuous flow of water. The synergy of these two materials led to the increase on the oil concentration in the liquid, which in turn enhanced the collision of emulsified oil droplets to aggregate into large ones in the emulsion and resulted separation from the water. Based on these findings, an aggregation-induced demulsification process was proposed to explain the above phenomenon, and the mechanism was confirmed by studying the distribution of oil droplets in emulsion with a controlled separation degree.
Collecting both enantiomorphs with high optical purity and yield in a single crystallization process can be achieved by adding aggregated polymeric “tailor-made” additives, known as nano-splitters. Inefficient preparation and large addition amount have hindered the practical application of such amazing nanoparticles. Herein, we report the first nano-splitters containing aggregation-induced emission luminogens prepared via polymerization-induced self-assembly of block copolymer, poly[(S)-2-(tert-butoxycarbonylamino)-6-(methacrylamido)hexanoic acid]-b-polystyrene, followed by the removal of tert-butoxycarbonyl groups. When added into the supersaturated solution of racemic amino acids (a.a.) with seeds, the fluorescent labeled nano-assemblies enantioselectivity dyed the crystals of S-a.a. and enabled the separation from colorless R-a.a. crystals in terms of fluorescent difference. Both enantiomers were obtained with high optical purity and yield (e.g., R- asparagine monohydrate, >99 ee%; S- asparagine monohydrate, ∼94 ee%; 88% total yield). Owing to a low detection limit of fluorescence, the addition amount was reduced to 0.03 wt% without remarkably compromising the ee values of both enantiomorphs. Due to the low addition amount and efficient synthesis, the output–input ratio was increased greatly.
The design of efficient aggregation-induced emission materials requires an improved understanding of photophysical processes in aggregated materials. Herein, the photophysical behavior of an Au(I) complex (R6) that exhibits intense room-temperature phosphorescence (RTP) in crystals is described. In addition, the photophysical processes related to RTP are discussed based on the structure of the molecular aggregates and the primary structure of the molecule. An extremely efficient S0–Tn direct transition is found to occur in the R6 crystal. Furthermore, intermolecular Au–Au interactions and the internal/external heavy-atom effects of Au atoms are demonstrated to enhance the electronic transitions involving intersystem crossing, namely, direct S0–Tn excitation, radiative T1–S0 transition (phosphorescence), and S1–Tn intersystem crossing. Because of the dense molecular packing, both Au–Au interactions and heavy-atom effects play important roles in the crystals. As a result, R6 shows more efficient RTP in crystals than in solution. These insights into the mechanism of highly efficient RTP in Au(I)-complex crystals are expected to advance the development of new luminogens for a variety of sensing and imaging applications.
The development and enrichment of high-performance organic fluorophores that simultaneously possess thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) properties is going pursued but remains a great challenge due to severe exciton quenching. Herein, a systematical investigation on imidazole moiety has successfully given rise to a series of highly efficient imidazole-based TADF-AIE luminogens for the first time. The attachment of two cyano functionalities on imidazole moiety can significantly increase the electron-withdrawing ability, so as to realize TADF emissions with small singlet-triplet energy gaps (ΔEST) values. Meanwhile, the installation of a steric hindrance group at N1 position of imidazole moiety can twist the geometry between imidazole and phenyl bridge, thus transforming imidazole derivative from an aggregation-caused quenching emitter into an AIE luminogen. Consequently, the non-doped organic light-emitting diodes (OLEDs) utilizing these TADF-AIE luminogens as emitters exhibit outstanding sky-blue and green emissions, with external quantum efficiency (EQE) as high as 20.0% and low efficiency roll-off (EQE at 1000 cd m−2, 16.1%). These values represent the state-of-the-art performance for all imidazole-based OLED devices, which illustrates the significant potential of imidazole derivatives in assembling high-performance OLEDs.
Since the discovery of the triphenylmethyl (trityl) cation 120 years ago, a variety of aromatic cations having various colors and luminescence properties have been rigorously studied. Many, differently substituted trityl cations have been synthesized, and their optical properties have been elucidated. However, the optical properties of the parent, non-substituted and highly reactive trityl cation, which was observed to be very weakly luminescent, have not been subjected to detailed investigation. In the effort described herein, we explored the optical nature of non-substituted trityl hexafluorophosphate (PF6) in the crystalline state. Trityl PF6 was found to exist as two crystal polymorphs including a yellow (Y) and an orange (O) form. Moreover, we observed that these crystalline forms display crystalline-state emission with different colors. The results of X-ray crystallographic analysis showed that the two polymorphs have totally different molecular packing arrangements. Furthermore, an investigation of their optical properties revealed that the O-crystal undergoes a distinct color change to yellow upon cooling as a consequence of a change in the nature of the charge transfer interaction between the cation and PF6 anion, and that both the Y- and O-crystal exhibit phosphorescence.
Chiral structures not only exist in nature widely, they also emerge in artificial systems, attracting myriad attentions due to their excellent mechanical, optical, electrical, and magnetic properties. Self-assembly of chiral block copolymers (BCPs*), where at least one block consists of chiral centers, represents a facile strategy to form helical/spiral/network structures with a controlled chirality. Usually, morphological chirality of BCP* assemblies was closely associated with molecular and conformational chirality of the chiral block. Generally, chiral assemblies arose from molecular chirality of BCPs*, transferring up in the assembly process and dictated the chirality at a higher hierarchical level. In contrast, notwithstanding similar assemblies could be observed from achiral BCPs under certain conditions, both left- and right-handed ones were usually observed simultaneously without a preference. Moreover, unique feature of BCPs* to access to controllable chiral assemblies affords an opportunity to prepare advanced functional materials. Herein, we dedicated a review on assembly of BCPs* into chiral assemblies in bulk/films, selective solvents, and confined spaces. The chiral transfer process in these assembly scenarios were discussed and highlighted as a key contributor to morphological chirality. Functionalities and representative applications of BCP* assemblies were also described, followed by present challenges and future prospects of BCP* self-assembly.
Spherical nucleic acids (SNAs) are composed of a nanoparticle core and a layer of densely arranged oligonucleotide shells. After the first report of SNA by Mirkin and coworkers in 1996, it has created a significant interest by offering new possibilities in the field of gene and drug delivery. The controlled aggregation of oligonucleotides on the surface of organic/inorganic nanoparticles improves the delivery of genes and nucleic acid–based drugs and alters and regulates the biological profiles of the nanoparticle core within living organisms. Here in this review, we present an overview of the recent progress of SNAs that has speeded up their biomedical application and their potential transition to clinical use. We start with introducing the concept and characteristics of SNAs as drug/gene delivery systems and highlight recent efforts of bioengineering SNA by imaging and treatmenting various diseases. Finally, we discuss potential challenges and opportunities of SNAs, their ongoing clinical trials, and future translation, and how they may affect the current landscape of clinical practices. We hope that this review will update our current understanding of SNA, organized oligonucleotide aggregates, for disease diagnosis and treatment.
In organic compounds, room temperature phosphorescence (RTP) is a rare, yet highly desirable, property that is important for a wide variety of applications, including tissue imaging, anticounterfeiting technologies, photodynamic therapy, and organic light-emitting devices. While most organic RTP molecules rely on heavy atoms or carbonyl functional groups to accelerate singlet-to-triplet intersystem crossing, in the past few years there have been several reports of RTP induced by boron-containing functional groups. This minireview covers the recent literature on RTP of crystalline boroorganic compounds and analyzes the connections between molecular structure, intermolecular interactions, and the resulting phosphorescence.
Fluorescent silica organic–inorganic nanohybrids which combine designable luminescence performance of organic fluorescent dyes and various outstanding advantages of silica nanomaterials have attracted increasing research interests in these fascinating areas. Optical transparency and facile functional modification properties of silica material provide great opportunities to integrate desired fluorescent molecules for various frontier luminous applications. However, conventional organic dyes are typically subject to aggregation-caused quenching due to their aggregation in silica matrix, which could be detrimental for their performance in sensing and biomedical applications. The appearance of aggregation-induced emission luminogens (AIEgens) paves a new way for developing highly efficient fluorescent silica nanohybrids (FSNs). FSNs with intensive luminescence could be obtained due to the formation of aggregates and the restricted intramolecular motion of AIEgens in silica inorganic matrix. In this review, the reported fabrication methodologies of various FSNs based on colloidal silica nanoparticles (SNs) and mesoporous SNs including physical entrapment and covalent strategies are summarized. Especially, the AIEgens-functionalized silica hybrid nanomaterials are introduced in detail. Furthermore, chemical sensing, biosensing, and bioimaging applications of resultant FSNs are also discussed.
Within the past two decades, chromophores, which show aggregation-induced emission (AIE), have gained considerable attention with respect to the development of luminescent liquid crystals. In contrast to common luminogens, AIE emitters do not suffer from aggregation-caused quenching of the emission in the solid state. In this review, we summarize the recent development in the field of AIE-active liquid crystals and show first model devices, which already prove the application potential of these materials. Currently, three different approaches are followed, to get access to luminescent liquid crystals––namely the synthetic approach yielding luminescent mesogens, the doping approach, and the supramolecular approach, which will be described and discussed in detail in this review.