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The development of a persistent luminescence system with long‐lived phosphorescence and color‐tunable afterglow at room temperature represents a challenge, largely due to the intensive non‐radiative deactivation pathway. In this study, an ultralong‐lived room temperature phosphorescence (RTP) system has been achieved using a hydrogen‐bonding strategy where poly(vinyl alcohol) (PVA) matrices were doped with tryptophan (Trp) derivatives. The PVA film doped with N‐α‐(9‐Fluorenylmethoxycarbonyl)‐L‐tryptophan (Fmoc‐L‐Trp) exhibited a long‐lived phosphorescence emission of up to 3859.70 ms, and a blue afterglow for a duration greater than 34 s, under ambient conditions. The introduction of two other fluorescent dyes (i. e. Rhodamine B and Basicred14) to the PVA film facilitates adjustment to the color of the afterglow from blue to orange, and pink, by a triplet‐to‐singlet Förster‐resonance energy transfer (TS‐FRET) process. These films have been successfully applied in silk‐screen printing and in multicolor afterglow light‐emitting diode (LED) arrays. [ABSTRACT FROM AUTHOR]

A novel coumarin hydrozone compound which exhibits piezochromic luminescence upon grinding was prepared. The piezofluorochromic properties were reversible upon fuming or heating. The intermolecular hydrogen bonds have been observed by single-crystal X-ray structural analysis, which are believed to make a major contribution to the piezofluorochromic properties. [ABSTRACT FROM AUTHOR]

It is challenging and desirable to develop an effective molecular design strategy to tune mechanofluorochromic (MFC) activity in organic molecules. Herein, three triphenylamine (TPA) derivatives were synthesized to investigate the MFC properties. The inclusion of iminodibenzyl, diphenylamine and carbazolyl units into the molecules causes some changes in the molecular conformation and packing pattern, which can lead to the variation of MFC activities. Among three TPA derivatives, T 1 exhibits excellent MFC performance upon grinding. In addition, the color change induced by grinding is revisable upon heating. In consideration of the good repeatability and sensitivity of MFC process, T 1 is chosen to prepare the rewritable papers and can be achieved in inkless writing technology. [Display omitted] [ABSTRACT FROM AUTHOR]

Mechanofluorochromic (MFC) materials display a photoluminescence color change in response to mechanical grinding and pressing. Development of an effective molecular design strategy to tune MFC activity is still challenging. Herein, seven 9, 10-distyrylanthracene (DSA)-based molecules are designed and synthesized as promising MFC materials. These molecules adopt a five-plane twisted spatial conformation that are composed of an anthryl ring and four phenyl rings. The inclusion of cyano groups and different substituents in this five-plane system causes some changes in the intramolecular charge transfer (ICT) and molecular conformation, which can directly induce new MFC activities. Among seven DSA derivatives, DSA-CN 5 exhibits the highest MFC activity upon grinding. Based on the good sensitivity and repeatability of MFC process as well as suitable stability of the ground state, DSA-CN 5 is selected to fabricate the rewritable papers and can be achieved in inkless printing technologies. [Display omitted] ● Seven new DSA derivatives are designed and successfully synthesized. ● Photophysical properties of DSA derivatives can be easily adjusted. ● DSA-CN 5 was selected to fabricate efficient rewritable papers and can be used in inkless printing technology. ● The printed content can be read distinctly both by the naked eyes and under UV lamp irradiation. [ABSTRACT FROM AUTHOR]