Halochromic Isoquinoline with Mechanochromic Triphenylamine: Smart Fluorescent Material for Rewritable and Self-Erasable Fluorescent Platform

Abstract

Halochromic isoquinoline attached mechanochromic triphenylamine, N-phenyl-N-(4-(quinolin-2-yl)phenyl)benzenamine (PQPBA) and tris(4-(quinolin-2-yl)phenyl)amine (TQPA), smart fluorescent materials exhibit thermo/mechanochromism and tunable solid state fluorescence and their unusual halochromic response in PMMA matrix have been used for fabricating rewritable and self-erasable fluorescent platforms. PQPBA and TQPA showed strong fluorescence in solution (Φ = 0.9290 (PQPBA) and 0.9160 (TQPA)) and moderate solid state fluorescence (Φ = 20 (PQPBA) and 17% (TQPA). Interestingly, they exhibited a rare temperature (0-100 °C) dependent positive fluorescence enhancement via activating radiative vibrational transition. The deaggregation of PQPBA and TQPA in PMMA polymer matrix lead to the enhancement of fluorescence intensity strongly and fabricated strong blue fluorescent thin films (Φ = 58% (PQPBA) and 54% (TQPA). The halochromic isoquinoline has been exploited for demonstrating reversible off-on fluorescence switching by acid (TFA (trifluoroacetic acid)/HCl) and base (NH) treatment in both solids as well as PMMA thin films. Importantly, rewritable and self-erasable fluorescent platform has been achieved by make use of unusual fluorescence responses of PQPBA/TQPA with TFA/HCl after exposing NH. Single crystal and powder X-ray diffraction (PXRD) studies provided the insight on the solid-state fluorescence and external stimuli-induced fluorescence changes.

Hybrid Chloroantimonates(III): Thermally Induced Triple‐Mode Reversible Luminescent Switching and Laser‐Printable Rewritable Luminescent Paper

“…The invisibility of the letters on paper under visible light reminds us that the paper coated with polycrystals of 1 can be applied as rewritable PL paper. To date, research on rewritable paper was mainly focused on the mechanochromism, solvatochromism, and photochromism, and so on, while the application of PL materials in rewritable PL paper was seldom reported. Owing to the competition between kinetic and thermodynamic crystallization processes during the cooling process of the molten of 1 , heating the designated area on the paper above T m1 would melt the polycrystals, and IL@2 with red emission would be formed after natural cooling the molten to RT.…”

Molecular Conformation‐ and Packing‐Controlled Excited State Intramolecular Proton Transfer Induced Solid‐State Fluorescence and Reversible Mechanofluorochromism

“…The incorporation of non-planar carbazole triarylamine unit coupled with solid state fluorescence of 2 and 4 is expected to exhibit stimuli-induced fluorescence switching since such non- 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 planar triphenylamine based derivatives are known to show AEE and mechanofluorochromism (MFC). [46][47][48][49][50][51][52] Crystalline materials of 2 and 4 showed fluorescence l max at 533 and 550 nm, respectively ( Figure 5, F f = 3.06, 2.26). The fluorescence spectra of 2 also showed a small hump at 550 nm.…”

Hybrid Chloroantimonates(III): Thermally Induced Triple‐Mode Reversible Luminescent Switching and Laser‐Printable Rewritable Luminescent Paper

“…Thei nvisibility of the letters on paper under visible light reminds us that the paper coated with polycrystals of 1 can be applied as rewritable PL paper.T od ate,r esearch on rewritable paper was mainly focused on the mechanochromism, [16] solvatochromism, [17] and photochromism, [18] and so on, [19] while the application of PL materials in rewritable PL paper was seldom reported. Owing to the competition between kinetic and thermodynamic crystallization processes during the cooling process of the molten of 1,h eating the designated area on the paper above T m1 would melt the polycrystals,a nd IL@2 with red emission would be formed after natural cooling the molten to RT.T he written contents can hardly be photocopied, which provides the opportunity for high-level anti-counterfeiting technology.T .A ida et al firstly reported the Cu I pyrazolate complexes with thermally tunable dichroic emission and their application in thermally rewritable phosphorescent paper as next-generation security technology.…”