Harnessing Excited-State Intramolecular Proton-Transfer Reaction via a Series of Amino-Type Hydrogen-Bonding Molecules

Abstract

A series of new amino (NH)-type hydrogen-bonding (H-bonding) compounds comprising 2-(2'-aminophenyl)benzothiazole and its extensive derivatives were designed and synthesized. Unlike in the hydroxyl (OH)-type H-bonding systems, one of the amino hydrogens can be replaced with electron-donating/withdrawing groups. This, together with a versatile capability for modifying the parent moiety, makes feasible the comprehensive spectroscopy and dynamics studies of amino-type excited-state intramolecular proton transfer (ESIPT), which was previously inaccessible in the hydroxyl-type ESIPT systems. Empirical correlations were observed among the hydrogen-bonding strength (the N-H bond distances and proton acidity), ESIPT kinetics, and thermodynamics, demonstrating a trend that the stronger N-H···N hydrogen bond leads to a faster ESIPT, as experimentally observed, and a more exergonic reaction thermodynamics. Accordingly, ESIPT reaction can be harnessed for the first time from a highly endergonic type (i.e., prohibition) toward equilibrium with a measurable ESIPT rate and then to the highly exergonic, ultrafast ESIPT reaction within the same series of amino-type intramolecular H-bond system.

A functional applied material on recognition of metal ion zinc based on the double azine compound

“…8). 27, 28, 29, 30, 31, 32 And the ESI-MS spectrum for the strong florescent complex also shown an obvious peak at m/z 452.3257 assignable to [ L  + Zn 2+  + H + ](Fig. S10).…”

Dormant acceptor activation of 10-hydroxybenzoquinline derivatives by excited-state intramolecular proton transfer

“…In recent articles [13,42,43] Chou et al [17] studied a new class of compounds where the ESIPT process occurs between two nitrogen atoms. The model compound 2-(2 0 -tosylaminophenyl) benzothiazole (PBT-NHTs) shows that the ESIPT rate strongly depends on the electron withdrawing power of the side groups R and R 0 .…”

“…The model compound 2-(2 0 -tosylaminophenyl) benzothiazole (PBT-NHTs) shows that the ESIPT rate strongly depends on the electron withdrawing power of the side groups R and R 0 . [13,42,43] when a Tosyl group is attached to the proton donor amino group the ESIPT process is ultrafast t PT < 150 fs. For other side groups the ESIPT process is rather slow or even not detected.…”

A theoretical investigation about the excited state behavior for 2‐(6'‐hydroxy‐2'‐pyridyl)benzimidazole: The water‐assisted excited state proton transfer process

“…To the best of our knowledge, molecules having a proton donor (OH or NH) or an acceptor (aromatic N or carbonyl O) may undergo the ESPT reaction upon electronic excitation along a pre‐existing hydrogen bond. Usually, the differences between the initial structure and the proton‐transferred form can result in novel photophysical and photochemical properties, based on which novel photoelectric applications have been developed, such as UV filters, molecular switches, fluorescence sensors, and so on.…”