Multi Stimuli-Responsive Aggregation-Induced Emission Active Polymer Platform Based on Tetraphenylethylene-Appended Maleic Anhydride Terpolymers

Time-Encoded Information Encryption with pH Clock Guided Broad-Spectrum Emission by Dynamic Assemblies

With growing threats from counterfeiting-based security breaches, multi-level and specific stimuli-responsive anti-counterfeiting devices and message encryption methods have attracted immense research interest. Fluorescence-based encryption from aggregation-induced emission (AIE)-based materials solves the problems to a considerable extent. However, the development of smarter patterns with hierarchical security levels alongside dynamic display is still challenging. To screen out this complication, we bring forward a pH-switchable fluorescent assembly of an AIEgen and an aliphatic acid. We later temporally direct the molecular assembly with the aid of a chemical trigger-regulated pH clock, generating a transitory multicolor emission, including transient white light generation. The pH-dependent emissions were further implemented in constructing smart multi-input fluorescent chemical AND gates. Subsequently, we integrate the time-gated emissive system to develop an advanced multi-dimensionally secure data encryption strategy. This novel approach enhances anti-counterfeiting measures by introducing an additional layer of security based on temporal characteristics.

Free radical copolymerization of 1,3-cyclooctadiene with maleic anhydride or N-substituted maleimides: a simple way to obtain high-performance transparent plastics

Herein, we report the free radical copolymerization of 1,3-cyclooctadiene and maleic anhydride or N-substituted maleimides. The obtained alternating copolymers have a fine-tuned Tg (ranging from 62 °C to 300 °C) and excellent thermal resistance and optical properties (up to 90% transmissivity).

Molecular engineering to enhance the reactive oxygen species generation of AIEgens and exploration of their versatile applications

Fluorescent dyes with aggregation-induced emission (AIE) characteristics have shown potential applications in the fields of biological imaging, photodynamic therapy and photothermal therapy, in which photosensitizers (PSs) play a crucial role. However, how to design high-quality PSs with high reactive oxygen species (ROS) generation efficiency remains unclear. In this contribution, an effective molecular design strategy to improve the ROS generation efficiency of AIE PSs was proposed. A series of tetraphenylethylene derivatives containing the pyridine ring or pyridinium with different substituents were designed and synthesized. All the molecules were weakly emissive when molecularly dissolved in solution but displayed intense emission upon aggregation, demonstrating a phenomenon of AIE characteristic. Pyridinium molecules could be used as visualization agents to specifically stain the mitochondria in living cells, while most of the molecules failed to generate ROS upon white light irradiation. In contrast, TPE-Pys-BP containing benzophenone produced ˙OH and 1O2 efficiently in the presence of light due to its large spin-orbit coupling constant to promote efficient intersystem crossing. Such a property allowed TPE-Pys-BP to serve as a PS to kill cancer cells using photodynamic therapy. TPE-Pys-BP also exhibited mechanochromic luminescence (ML), and its emission could be reversibly switched between two distinct colors through repeated grinding and fuming processes. A security paper was fabricated using the ML properties of TPE-Pys-BP.

Synthesis and Characterization of Tetraphenylethene AIEgen-Based Push-Pull Chromophores for Photothermal Applications: Could the Cycloaddition-Retroelectrocyclization Click Reaction Make Any Molecule Photothermally Active?

Three new tetraphenylethene (TPE) push-pull chromophores exhibiting strong intramolecular charge transfer (ICT) are described. They were obtained via [2 + 2] cycloaddition-retroelectrocyclization (CA-RE) click reactions on an electron-rich alkyne-tetrafunctionalized TPE (TPE-alkyne) using both 1,1,2,2-tetracyanoethene (TCNE), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F₄-TCNQ) as electron-deficient alkenes. Only the starting TPE-alkyne displayed significant AIE behavior, whereas for TPE-TCNE, a faint effect was observed, and for TPE-TCNQ and TPE-F₄-TCNQ, no fluorescence was observed in any conditions. The main ICT bands that dominate the UV-Visible absorption spectra underwent a pronounced red-shift beyond the near-infrared (NIR) region for TPE-F₄-TCNQ. Based on TD-DFT calculations, it was shown that the ICT character shown by the compounds exclusively originated from the clicked moieties independently of the nature of the central molecular platform. Photothermal (PT) studies conducted on both TPE-TCNQ and TPE-F4-TCNQ in the solid state revealed excellent properties, especially for TPE-F4-TCNQ. These results indicated that CA-RE reaction of TCNQ or F₄-TCNQ with donor-substituted are promising candidates for PT applications.