An AIE-ESIPT-active compound was rationally designed and facilely developed, which exhibits multifunctional applications in inkless rewritable paper, a colorimetric/fluorescent dual-channel sensor for Zn²⁺ ions and fluorescence imaging of Zn²⁺ ions in living cells.

Two different polymorphs of a new tetraphenylethene-based Schiff base 4-methoxy-2-(((4-(1,2,2-triphenylvinyl)phenyl)imino)methyl)phenol (TPENOMe) were obtained, which exhibit totally different photochromic and fluorescence properties. The square block-like crystal (TPENOMe-a) exhibits very weak fluorescence and reversible photochromic behavior, while the needle-like crystal (TPENOMe-b) emits relatively stronger orange fluorescence without photochromism. Detailed investigations of the crystal structures, fluorescence spectra and femtosecond transient absorption spectra of the two different polymorphs demonstrate that the different photoinactivation ways resulting from significantly different crystal packing styles may be responsible for the unprecedented various properties. Moreover, TPENOMe-a can be applied as visible light responsive rewritable paper with inkless writing and self-erasing properties. For the rewritable paper, 450 nm blue light can serve as the pen, while 460 to 570 nm light and white light are employed as the eraser. TPENOMe-b combined with TPENOMe-a can be used as a reusable data encryption material with both static and dynamic encryption–decryption processes.

A new tetraphenylethene-based Schiff base N-5-nitrosalicylidene-4-tetraphenylethenylamine (NSTPE) was synthesized based on 4-tetraphenylethenylamine and 5-nitrosalicylaldehyde, and its structure was fully characterized by ¹H NMR, ¹³C NMR, MS and single crystal X-ray diffraction analysis. The study of optical properties shows that the emission exhibits an interesting “on–off–on” switching property with a U-shaped tendency when adding water into the tetrahydrofuran solution of NSTPE, showing twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) characteristics. Moreover, the compound exhibits reversible piezofluorochromic properties.

It is important to develop fluorescent probes for rapid, selective, and sensitive detection of highly toxic hydrazine in both environmental and biological science. In this text, under mild conditions, a novel near-infrared (NIR) ratiometric and on–off fluorescent probe 1 was synthesized based on hemicyanine and coumarin derivatives, which can detect hydrazine with high selectivity and anti-interference over other amines, biological species, anions and metal ions. The limit of quantification (LOQ) value was 0–400 μM and the detection limit could be as low as 560 nM.