Hydrogen bonding interactions induced excited state proton transfer and fluoride anion sensing mechanism for 2‐(3,5‐dichloro‐2,6‐dihydroxy‐phenyl)‐benzoxazole‐5‐carboxylicacid

Abstract

The present work explores and reports photo-induced behavior and excited state intramolecular proton transfer (ESIPT) process for the novel 2-(3,5-dichloro-2,6-dihydroxy-phenyl)-benzoxazole-5-carboxylicacid (DICH) compound. Our theoretical investigation implies that two intramolecular hydrogen bonds (O1─H2ÁÁÁN3 or O4─H5ÁÁÁO6) of DICH form are strengthening in the first excited state by comparing bond lengths, bond angles, and infrared (IR) spectra, which may facilitate the ESIPT process effectively. Particularly, the changes of O1─H2ÁÁÁN3 are bigger than O4─H5ÁÁÁO6, which demonstrates that the ESIPT is more likely to happen along with O1─H2ÁÁÁN3.Within the framework of MOs analysis, intramolecular charge transfer phenomenon can be found, which could be a reasonable evidence for confirming the occurrence of the ESPT process in the S 1 state. We theoretically construct the potential energy curves for DICH system based on fixing both O1─H2 and O4─H5 bond lengths and optimizing structures in both S 0 and S 1 states.Through the comparisons of potential barriers among stable configurations, we confirm the S 1 -state DICH-PT1 (proton-transfer tautomer along with O1─H2ÁÁÁN3) should be the most reasonable configuration ascribed to previous experimental emission peak. Furthermore, we also predict and explain the fluoride-sensing mechanism for DICH system that the deprotonation reaction bringing from fluoride anion inhibits the initial ESIPT process of DICH, which results in the novel changes of ultraviolet-visible (UV-Vis) spectra that plays the roles in fluorescence response. We sincerely hope this work could provide essential insights into the design and function of ESIPT as well as florescence sensor for optoelectronic applications. K E Y W O R D SAIM, ESIPT, fluoride-triggered fluorescence response, MOs, potential energy surfaces

Benzothiazole‐based chemosensor: a quick dip into its anion sensing mechanism

“…[ 22 ] Moreover, the anion sensing mechanism of ESIPT‐based fluorescent probes has been investigated theoretically with the aid of computational methods. [ 22,27–29 ]…”

Intramolecular Proton Transfer in the Isomerization of Hydroxyacetone: A Detailed Characterization Based on Reaction Force Analysis and the Bond Fragility Spectrum

“…In spite of the simplicity implied by this superficial explanation, PT reactions have been the subject F I G U R E 1 Reaction mechanism for isomerization of hydroxyacetone to 2-hydroxypropanal of numerous experimental [15][16][17][18][19] and theoretical [20][21][22][23] studies for decades. This fascination with PT reactions stems from the many unique scenarios they are involved in, for instance they occur in both intermolecular [24] and intramolecular [25] reactions, ground state thermal-induced processes, [26][27][28] excited state photoinduced processes, [29][30][31][32] and even processes coupled with electron transfer. [33] Each scenario presenting a unique set of physical challenges.…”

Intramolecular proton transfer in the isomerization of hydroxyacetone: Characterization based on reaction force analysis and the bond fragility spectrum

“…Reaction mechanism for isomerization of hydroxyacetone to 2-hydroxypropanal of numerous experimental [15][16][17][18][19] and theoretical [20][21][22][23] studies for decades. This fascination with PT reactions stems from the many unique scenarios they are involved in, for instance they occur in both intermolecular [24] and intramolecular [25] reactions, ground state thermal-induced processes, [26][27][28] excited state photoinduced processes, [29][30][31][32] and even processes coupled with electron transfer. [33] Each scenario presenting a unique set of physical challenges.…”