An ESIPT fluorophore with a switchable intramolecular hydrogen bond for applications in solid-state fluorochromism and white light generation

Abstract

Acid/base-switched solid-state fluorochromism and excitation-wavelength-dependent fluorescence color tuning have been demonstrated using an ESIPT fluorophore with a switchable intramolecular hydrogen bond.

A quantum-chemical insight into the tunable fluorescence color and distinct photoisomerization mechanisms between a novel ESIPT fluorophore and its protonated form

“…Previous spectroscopic experiments revealed that BTImP could emit green fluorescence with an emission maximum at 542 nm in tetrahydrofuran (THF) solution; however, the fluorescence color was remarkably changed to orange in acetic acid (AcOH) solution, exhibiting a large red shift of 1379 cm −1 in comparison with that in the THF solution [1]. The green fluorescence was unambiguously ascribed to the emission of BTImP, while the orange fluorescence was speculated to originate from the emission of its protonated form at the Im side [1].…”

“…They observed that the fluorescence color of BTImP was tunable from green to orange on the basis of the switching of intramolecular hydrogen-bonding sites by acid/base stimuli. What is more, such a phenomenon could be achieved in a BTImP-doped Nafion film by writing a letter on it with acidic or basic water as ink, which provides a new possibility for applications such as rewritable data recording using water as ink [1].…”

“…Recently, Sakai et al reported the synthesis and comprehensive optical properties of a novel ESIPT fluorophore bearing the imidazole (Im) and benzothiazole (BT) moieties, 2-(1,3-benzothiazol-2-yl)-4-methoxy-6-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (BTImP) [1]. They observed that the fluorescence color of BTImP was tunable from green to orange on the basis of the switching of intramolecular hydrogen-bonding sites by acid/base stimuli.…”

“…This work was motivated by the report of a switchable fluorescence color based upon the switching of the excited-state intramolecular proton transfer (ESIPT) sites by means of acidic stimuli and the desire to theoretically shed light on the underlying mechanisms [1]. It is wellknown that an ESIPT molecule possesses both proton-donating and proton-accepting groups, thereby forming a five-, six-or even seven-membered-ring intramolecular hydrogen bond (H-bond) [2][3][4][5][6][7][8][9].…”

“…Owing to such important applications, organic dyes undergoing ESIPT continue to receive wide attention from the experimental and theoretical aspects [1,[22][23][24][25][26][27][28][29][30][31][32][33][34]. Recently, Sakai et al reported the synthesis and comprehensive optical properties of a novel ESIPT fluorophore bearing the imidazole (Im) and benzothiazole (BT) moieties, 2-(1,3-benzothiazol-2-yl)-4-methoxy-6-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (BTImP) [1].…”