Triplet excitons in organic molecules underscore a variety of processes and technologies as a result of their long lifetime and spin multiplicity Organic phosphorescence, which originates from triplet excitons, has potential for the development of a new generation of organic optoelectronic materials and biomedical agents However, organic phosphorescence is typically only observed at cryogenic temperatures and under inert conditions in solution, which severely restricts its practical applications In the past few years, room-temperature-phosphorescent systems have been obtained based on organic aggregates Rapid advances in molecular-structure design and aggregation-behaviour modulation have enabled substantial progress, but the mechanistic picture is still not fully understood because of the high sensitivity and complexity of triplet-exciton behaviour This Review analyses key photophysical processes related to triplet excitons, including intersystem crossing, radiative and non-radiative decay, and quenching processes, to illustrate the intrinsic structure–property relationships and draw clear and integrated design principles The resulting strategies for the development of efficient and persistent room-temperature-phosphorescent systems are discussed, and newly emerged applications based on these materials are highlighted Advances in molecular-structure design and modulation of the aggregation behaviour have enabled much progress in the observation of room-temperature phosphorescence from organic aggregates This Review analyses key photophysical processes related to triplet excitons, illustrating the intrinsic structure–property relationships and identifying strategies to design efficient and persistent room-temperature-phosphorescent systems

Room-temperature phosphorescence from organic aggregates

Metal-organic frameworks (MOFs) are an interesting and useful class of coordination polymers, constructed from metal ion/cluster nodes and functional organic ligands through coordination bonds, and have attracted extensive research interest during the past decades. Due to the unique features of diverse compositions, facile synthesis, easy surface functionalization, high surface areas, adjustable porosity, and tunable biocompatibility, MOFs have been widely used in hydrogen/methane storage, catalysis, biological imaging and sensing, drug delivery, desalination, gas separation, magnetic and electronic devices, nonlinear optics, water vapor capture, etc. Notably, with the rapid development of synthetic methods and surface functionalization strategies, smart MOF-based nanocomposites with advanced bio-related properties have been designed and fabricated to meet the growing demands of MOF materials for biomedical applications. This work outlines the synthesis and functionalization and the recent advances of MOFs in biomedical fields, including cargo (drugs, nucleic acids, proteins, and dyes) delivery for cancer therapy, bioimaging, antimicrobial, biosensing, and biocatalysis. The prospects and challenges in the field of MOF-based biomedical materials are also discussed.

Metal-Organic Frameworks for Biomedical Applications.

Materials exhibiting long-lived, persistent luminescence in the visible spectrum are useful for applications in the display, information encryption and bioimaging sectors1–4. Herein, we report the development of several organic phosphors that provide colour-tunable, ultra-long organic phosphorescence (UOP). The emission colour can be tuned by varying the excitation wavelength, allowing dynamic colour tuning from the violet to the green part of the visible spectrum. Our experimental data reveal that these organic phosphors can have an ultra-long lifetime of 2.45 s and a maximum phosphorescence efficiency of 31.2%. Furthermore, we demonstrate the applications of colour-tunable UOP for use in a multicolour display and visual sensing of ultraviolet light in the range from 300 to 360 nm. The findings open the opportunity for the development of smart luminescent materials and sensors with dynamically controlled phosphorescence. Organic phosphors with ultra-long lifetimes and an emission colour that can be tuned by the excitation wavelength are reported.

Colour-tunable ultra-long organic phosphorescence of a single-component molecular crystal

Once considered the exclusive property of metal complexes, the phenomenon of room-temperature phosphorescence (RTP) has been increasingly realized in pure organic luminophores recently. Using precise molecular design and synthetic approaches to modulate their weak spin-orbit coupling, highly active triplet excitons, and ultrafast deactivation, organic luminophores can be endowed with long-lived and bright RTP characteristics. This has sparked intense explorations into organic luminophores with enhanced RTP features for different applications. This Review discusses the fundamental mechanism of RTP in pure organic luminophores, followed by design principles, enhancement strategies, and formulation methods to achieve highly phosphorescent and long-lived organic RTP luminophores even in aqueous media. The current challenges and future directions of this field are also discussed in the summary and outlook.

/pdf/enhancing-the-performance-of-pure-organic-room-temperature-5b503whsan.pdf

Enhancing the performance of pure organic room-temperature phosphorescent luminophores

Confining molecules can fundamentally change their chemical and physical properties. Confinement effects are considered instrumental at various stages of the origins of life, and life continues to rely on layers of compartmentalization to maintain an out-of-equilibrium state and efficiently synthesize complex biomolecules under mild conditions. As interest in synthetic confined systems grows, we are realizing that the principles governing reactivity under confinement are the same in abiological systems as they are in nature. In this Review, we categorize the ways in which nanoconfinement effects impact chemical reactivity in synthetic systems. Under nanoconfinement, chemical properties can be modulated to increase reaction rates, enhance selectivity and stabilize reactive species. Confinement effects also lead to changes in physical properties. The fluorescence of light emitters, the colours of dyes and electronic communication between electroactive species can all be tuned under confinement. Within each of these categories, we elucidate design principles and strategies that are widely applicable across a range of confined systems, specifically highlighting examples of different nanocompartments that influence reactivity in similar ways.

Chemical reactivity under nanoconfinement

In 2008, our group reported on pillar[n]arenes as novel-shaped macrocyclic compounds. Owing to the para-bridge connection between 1,4-dialkoxybenzene units, pillar[n]arenes adopt a highly symmetrical pillar and polygonal-shaped structure, which is different from typical host molecules. Because pillar[n]arenes exhibit these highly symmetrical structures with high functionality, many chemists have used pillar[n]arenes as building blocks to construct supramolecular assemblies. Therefore, pillar[n]arenes have applications in various fields such as material science and biochemistry. We discuss the host–guest ability of pillar[n]arenes, application of pillar[5]arenes as catalysts and reductants, and assembly of pillar[n]arenes on surfaces based on their pillar-shaped structures. The highly ordered assembled structures, based on their highly symmetrical polygonal prism shape, are also discussed.

Molecular Space Chemistry Based on Pillar[n]arenes

Colloidally stable polystyrene (PS)–polyhedral oligomeric silsesquioxane (POSS) element-block polymer particles were fabricated by heterocoagulation method using negatively charged POSS and positively charged PS seed particles in water. POSS was adsorbed to the PS particle surface via electrostatic interaction and the resulting particles had PS core and POSS shell morphology.

Polystyrene–Polyhedral Oligomeric Silsesquioxane Core–Shell Element-block Polymer Particles Fabricated via Heterocoagulation Method

Regulation of dynamic chirality and conversion of the regulated dynamic chirality to static chirality is challenging and important for their applications. In their Research Article (e202217971), Tomoki Ogoshi and co-workers report the control and amplification of dynamic planar chirality of pillar[5]arene by guest solvents and crystallization, respectively. The regulated dynamic chirality was changed to static chirality by introducing bulky stoppers. The image shows the conversion of the dynamic-to-static planar chirality in pillar[5]arenes (cars) by introducing bulky stoppers (pit stop). 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/ange.202304371

Innenrücktitelbild: Dynamic‐to‐Static Planar Chirality Conversion in Pillar[5]arenes Regulated by Guest Solvents or Amplified by Crystallization (Angew. Chem. 19/2023)

Ca2+/calmodulin-dependent protein kinase II (CaMKII) has long been central in synaptic plasticity research. CaMKII is a dodecameric serine/threonine kinase that has been essentially conserved across metazoans for over a million years. While the mechanisms of CaMKII activation are well studied, its “behavior” at the molecular level has remained unobserved. Here, high-speed atomic force microscopy was used to visualize the activity-dependent structural dynamics of rat/hydra/C. elegans CaMKII in various states at nanometer resolution. Among the species, rat CaMKII underwent internal kinase domain aggregation in an activity-dependent manner and showed a higher tolerance to dephosphorylation by phosphatase. Our findings suggest that mammalian CaMKII has evolutionarily acquired a new structural form and a tolerance to phosphatase to maintain robust CaMKII activity for proper neuronal function. One-Sentence Summary High-speed atomic force microscopy reveals the activity-dependent structural dynamics of rat/hydra/C. elegans CaMKII

/pdf/evolutionarily-acquired-activity-dependent-transformation-of-16amom9m.pdf

Evolutionarily acquired activity-dependent transformation of the CaMKII holoenzyme

Preparation of Nano-Sized Silver Particles and Organic-Inorganic Hybrid Material from Phenolic Polymer

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