Hydrolyzation-Triggered Ultralong Room-Temperature Phosphorescence in Biobased Nonconjugated Polymers

Recent Progress in Nonconventional Luminescent Macromolecules and their Applications

Traditional π-conjugated luminescent macromolecules typically suffer from aggregation-caused quenching (ACQ) and high cytotoxicity, and they require complex synthetic processes. In contrast, nonconventional luminescent macromolecules (NCLMs) with nonconjugated structures possess excellent biocompatibility, ease of preparation, unique luminescence behavior, and emerging applications in optoelectronics, biology, and medicine. NCLMs are currently believed to produce inherent luminescence due to through-space conjugation of overlapping electron orbitals in solid/aggregate states. However, as experimental facts continue to exceed expectations or even overturn some previous assumptions, there is still controversy about the detailed luminous mechanism of NCLMs, and extensive studies are needed to further explore the mechanism. This Perspective highlights recent progress in NCLMs and classifies and summarizes these advances from the viewpoint of molecular design, mechanism exploration, applications, and challenges and prospects. The aim is to provide guidance and inspiration for the huge fundamental and practical potential of NCLMs.

Recent Advances in Room-Temperature Phosphorescence Metal-Organic Hybrids: Structures, Properties, and Applications

Metal-organic hybrid (MOH) materials with room-temperature phosphorescence (RTP) have drawn attention in recent years due to their superior RTP properties of high phosphorescence efficiency and ultralong emission lifetime. Great achievement has been realized in developing MOH materials with high-performance RTP, but a systematic study on MOH materials with RTP feature is lacking. This review highlights recent advances in metal-organic hybrid RTP materials. The molecular packing, the photophysical properties, and their applications of metal-organic hybrid RTP materials are discussed in detail. Metal-organic hybrid RTP materials can be divided into six parts: coordination polymers, metal-organic frameworks (MOFs), metal-halide hybrids, organic ionic crystals, organic ionic polymers, and organic-inorganic hybrid perovskites. These RTP materials have been successfully applied in time-resolved data encryption, fingerprint recognition, information logic gates, X-ray imaging, and photomemory. This review not only provides the basic principles of designing RTP metal-organic hybrids, but also propounds the future research prospects of RTP metal-organic hybrids. This review offers many effective strategies for developing metal-organic hybrids with excellent RTP properties, thus satisfying practical applications.

Recent progress in ion-regulated organic room-temperature phosphorescence

Organic room-temperature phosphorescence (RTP) materials have attracted considerable attention for their extended afterglow at ambient conditions, eco-friendliness, and wide-ranging applications in bio-imaging, data storage, security inks, and emergency illumination. Significant advancements have been achieved in recent years in developing highly efficient RTP materials by manipulating the intermolecular interactions. In this perspective, we have summarized recent advances in ion-regulated organic RTP materials based on the roles and interactions of ions, including the ion-π interactions, electrostatic interactions, and coordinate interactions. Subsequently, the current challenges and prospects of utilizing ionic interactions for inducing and modulating the phosphorescent properties are presented. It is anticipated that this perspective will provide basic guidelines for fabricating novel ionic RTP materials and further extend their application potential.

Amphiphilic Polyurethane with Cluster-Induced Emission for Multichannel Bioimaging in Living Cell Systems

The development of single-component materials with low cytotoxicity and multichannel fluorescence imaging capability is a research hotspot. In the present work, highly electron-deficient pyrazine monomers were covalently connected into a polyurethane backbone using addition polymerization with terminal poly(ethylene glycol) monomethyl ether units containing a high density of electron pairs. Thereby, an amphiphilic polyurethane-pyrazine (PUP) derivative has been synthesized. The polymer displays cluster-induced emission through compact inter- and/or intramolecular noncovalent interactions and extensive through-space electron coupling and delocalization. Molecular rigidity facilitates red-shifted emission. Based on hydrophilic/hydrophobic interactions and excitation dependence emission at low concentrations, PUP has been self-assembled into fluorescent nanoparticles (PUP NPs) without additional surfactant. PUP NPs have been used for cellular multicolor imaging to provide a variety of switchable colors on demand. This work provides a simple molecular design for environmentally sustainable, luminescent materials with excellent photophysical properties, biocompatibility, low cytotoxicity, and color modulation.

A processable, scalable, and stable full-color ultralong afterglow system based on heteroatom-free hydrocarbon doped polymers

Although room-temperature phosphorescence (RTP) organic materials are a widely-studied topic especially popular in recent decades, long-lived RTP able to fulfil broad time-resolved application requirements reliably, are still rare. Polymeric materials doped with phosphorescent chromophores generally feature high productivity and diverse applications, compared with their crystalline counterparts. This study proves that pure polycyclic aromatic hydrocarbons (PAHs) may even outperform chromophores containing hetero- or heavy-atoms. Full-color (blue, green, orange and red) polymer-PAHs with lifetimes >5000 ms under ambient conditions are constructed, which provide impressive values compared to the widely reported polymer-based RTP materials in the respective color regions. The polymer-PAHs could be fabricated on a large-scale using various methods (solution, melt and in situ polymerization), be processed into diverse forms (writing ink, fibers, films, and complex 3D architectures), and be used in a range of applications (anti-counterfeiting, information storage, and oxygen sensors). Plus their environmental (aqueous) stability makes the polymer-PAHs a promising option to expand the portfolio of organic RTPs.

Chiral Luminescent Liquid Crystal with Multi-State-Reversibility: Breakthrough in Advanced Anti-Counterfeiting Materials

Creating a security material that carries distinct information in reflective color, fluorescence, and chiroptical property will enhance anti-counterfeiting levels to deter counterfeits ranging from currencies to pharmaceuticals, but is proven extremely challenging. In this work, an advanced anti-counterfeiting material, with three-state of each mode reversibly converted into multi-mode materials including reflective color, fluorescence, and circularly polarized luminescence signal, is constructed by loading photofluorochromic spiropyran (SP) and zinc ion (Zn²⁺ ) into the chiral liquid crystal. Under UV irradiation, the complexes of SP and Zn²⁺ will be transformed into merocyanine (MC) and MC-Zn²⁺ , while the energy transfer occurs from MC-Zn²⁺ to MC. Upon heating, MC is easy to recover to SP, while the MC-Zn²⁺ remains unchanged. The MC and MC-Zn²⁺ can be transformed into the SP and Zn²⁺ under visible light irradiation. The three states of each mode can reversibly convert. Furthermore, the reflective color or fluorescence of each state shows different intensities under left- and right-handed circular polarized filters, enabling easy distinguishing by naked eyes. The advanced anti-counterfeiting method with multi-state of each mode for multi-mode encryption information output will provide a new concept for designing and fabricating multi-mode anti-counterfeiting materials, improving the security level for practical application.