Butterfly-like molecules of oxacalix[2]arene[2]pyrazine (OAP) are reported, which exhibit the typical characteristics of aggregation-induced emission (AIE) via the restriction of intramolecular vibration (RIV) mechanism. Unlike any of the reported RIV-type AIE molecules, the synthetic procedures of which are complicated and have associated high costs, OAP AIEgens can be synthesized in a facile manner by a one-step catalyst-free reaction using commercially available materials. Notably, OAP AIEgens are ideal ligands for constructing metal-organic frameworks (MOFs) due to their built-in pyrazine coordination sites. OAP-based MOFs exhibit multiple potential applications in reversible gas response, encrypted information storage, and construction of white light-emitting devices. This work builds on RIV-type AIEgens, offers additional selections of bridging ligands for constructing luminescent MOFs and provides a visualized prototype to understand the effect of the RIV process on the luminescence properties of MOFs.

Restriction of Intramolecular Vibration in Aggregation-Induced Emission Luminogens: Applications in Multifunctional Luminescent Metal-Organic Frameworks.

In recent years, the use of aggregation-induced emission luminogens (AIEgens) for biological imaging and phototherapy has become an area of intense research. However, most traditional AIEgens suffer from undesired aggregation in aqueous media with “always on” fluorescence, or their targeting effects cannot be maintained accurately in live cells with the microenvironment changes. These drawbacks seriously impede their application in the fields of bio-imaging and antitumor therapy, which require a high signal-to-noise ratio. Herein, we propose a molecular design strategy to tune the dispersity of AIEgens in both lipophilic and hydrophilic systems to obtain the novel near-infrared (NIR, ∼737 nm) amphiphilic AIE photosensitizer (named TPA-S-TPP) with two positive charges as well as a triplet lifetime of 11.43 μs. The synergistic effects of lipophilicity, electrostatic interaction, and structure-anchoring enable the wider dynamic range of AIEgen TPA-S-TPP for mitochondrial targeting with tolerance to the changes of mitochondrial membrane potential (ΔΨm). Intriguingly, TPA-S-TPP was difficult for normal cells to be taken up, indicative of low inherent toxicity for normal cells and tissues. Deeper insight into the changes of mitochondrial membrane potential and cleaved caspase 3 levels further revealed the mechanism of tumor cell apoptosis activated by AIEgen TPA-S-TPP under light irradiation. With its advantages of low dark toxicity and good biocompatibility, acting as an efficient theranostic agent, TPA-S-TPP was successfully applied to kill cancer cells and to efficiently inhibit tumor growth in mice. This study will provide a new avenue for researchers to design more ideal amphiphilic AIE photosensitizers with NIR fluorescence.

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Activation of apoptosis by rationally constructing NIR amphiphilic AIEgens: surmounting the shackle of mitochondrial membrane potential for amplified tumor ablation

The strong emission in the solid state and the feasibility of introducing stimuli responsiveness make aggregation-induced-emission luminogens promising for optical information encryption. Yet, the vast majority of previous reports rely on subtle changes in the molecular conformation or intermolecular interactions, limiting the robustness, multiplicity, capacity, and security of the resulting cryptosystems. Herein, a versatile cryptographic system is presented based on three interconnected and orthogonal covalent transformations concerning a tetraphenylethylene-maleimide conjugate. The cryptosystem is adapted into four configurations with different functionalities by organizing the reactions and molecules in different ways. These variants either balance the accessibility and security of the encrypted information or improve the security and density in data encryption. Significantly, they allow variable decryption from a single encryption and reconstruction of the chemical nature hidden in the fluorescent pattern can only be accessed through given algorithms. These results highlight the importance of multi-component synergies in advancing information encryption systems, which is enabled by the robustness and diversity stemming from the covalent nature of these transformations.

An Adaptable Cryptosystem Enabled by Synergies of Luminogens with Aggregation-Induced-Emission Character.

Rationally developing an intelligent tool for high-contrast fluorescence imaging of latent fingerprints (LFPs) is gaining much concern in many applications such as medical diagnostics and forensic investigations. Herein, the off-on fluorescent polymer micelles (PMs) have been rationally designed and synthesized for high-contrast fluorescence imaging of LFPs through the cross-linking reaction of hydrazine (N2H4) and aldehyde group of polymer. Excitingly, the cross-linking (N2H4) induced emission of PMs has the property of aggregation-induced emission (AIE) and excited state intramolecular proton transfer (ESIPT), which could effectively address the notorious aggregation-caused quenching (ACQ) effects of conventional organic dyes. In addition, the cross-linking strategy can not only improve structural stability of PMs but also enhance its fluorescence brightness. The experiment results demonstrated that PMs showed high water dispersibility (100% aqueous solution), high selectivity, large Stokes shift (∼150 nm), good photostability, and excellent long-term stability. Because of the hydrophobic interaction between the PMs and fingerprint components, the PMs preferentially adhered onto the ridges of fingerprint, and then cross-linking (N2H4) induced emission properties endowed the PMs for high-contrast imaging of LFPs in different substrates, especially the levels 1-3 details of LFPs. We expect that this strategy will provide vital support for LFPs technology.

Cross-Linking Induced Emission of Polymer Micelles for High-Contrast Visualization Level 3 Details of Latent Fingerprints.

Fluorescent probes in public health and public safety

A water-soluble probe, TPA-1OH, with aggregation-induced emission activity is synthesized and used for expedient real-time fluorescence in situ visualization of latent fingerprints (LFPs). A TPA-1O...

Real-Time Fluorescence in Situ Visualization of Latent Fingerprints Exceeding Level 3 Details Based on Aggregation-Induced Emission

The invention relates to the field of new material fluorescence probes, and more particularly to the application of an aggregation-induced fluorescence probe in fingerprint fluorescence imaging. The fluorescence probe has a general structural formula shown in formula (1): wherein R1 and R2 are substituent groups at any position of Ar1 and Ar2, and at least one of R1 and R2 is a hydrophilic group;and Ar1 and Ar2 are aromatic rings. By using the fluorescent probe provided by the invention and by using an ordinary digital single lens reflex camera, a potential fingerprint on the surface of a smooth object can be displayed by an ultraviolet light exciting method. Fluorescence fingerprint imaging with low background noise, high brightness and high definition is obtained more conveniently and directly.

Tian Rui

Papers

Real-Time Fluorescence in Situ Visualization of Latent Fingerprints Exceeding Level 3 Details Based on Aggregation-Induced Emission

Application of aggregation-induced fluorescence probe in fingerprint fluorescence imaging