Force‐Induced Turn‐On Persistent Room‐Temperature Phosphorescence in Purely Organic Luminogen

Abstract

Research of purely organic room‐temperature phosphorescence (RTP) materials has been a hot topic, especially for those with stimulus response character. Herein, an abnormal stimulus‐responsive RTP effect is reported, in which, purely organic luminogen of Czs‐ph‐3F shows turn‐on persistent phosphorescence under grinding. Careful analyses of experimental results, coupled with the theoretical calculations, show that the transition of molecular conformation from quasi‐axial to quasi‐equatorial of the phenothiazine group should be mainly responsible for this exciting result. Furthermore, the applications of stylus printing and thermal printing are both successfully realized, based on the unique RTP effect of Czs‐ph‐3F.

Mechanochromic, thermoresponsive and triboluminescence behaviors of one divinyl thioxanthene based AIE luminogen with variable conformations

“…The introduction of a conformation variable moiety into chromophores is an efficient strategy to design dynamic materials, which may generate multiple thermodynamically metastable states through conformational change under external stimuli. [19][20][21] In fact, a variety of smart luminescent materials have been achieved by Minakata, 22 Li 23 and Xu 24 by virtue of saddle-shaped phenothiazine building blocks bearing two distinct quasi-axial and quasi-equatorial conformers. However, conformation flexible chromophores are still limited and underdeveloped.…”

The influence of π–π stacking on the room temperature phosphorescence of phenothiazine 5,5-dioxide derivatives

“…For these target compounds, the 1,2,3-trifluorophenyl group was introduced to all of them to strengthen the intermolecular hydrogen bonding and inhibit the non-radiative transition, while the substituents in the 2-position of the phenothiazine 5,5-dioxide group were changed from each other, with the aim to accurately adjust the molecular packing and investigate the structure–packing–RTP property relationship. 26–28…”

“…was introduced to all of them to strengthen the intermolecular hydrogen bonding and inhibit the non-radiative transition, while the substituents in the 2-position of the phenothiazine 5,5-dioxide group were changed from each other, with the aim to accurately adjust the molecular packing and investigate the structure-packing-RTP property relationship. [26][27][28] Excitingly, accompanying the adjustment of the substituent groups on the 2-position of the phenothiazine 5,5-dioxide ring from the methoxyl group to a bromine atom, and then to hydrogen, fluorine and chlorine atoms, the RTP lifetimes in crystals of the corresponding luminogens increased from 144 ms (PTZO-CH 3 O) and 179 ms (PTZO-Br) to 332 ms (PTZO-H), and then to 446 ms (PTZO-F) and 745 ms (PTZO-Cl). Single crystal analyses indicated that the minor differences in the substituents could lead to much different intermolecular p-p interactions, thus resulting in the changed RTP properties.…”