Sensing mechanism for a fluoride chemosensor: invalidity of excited-state proton transfer mechanism

Abstract

Our density functional theory (DFT)/time-dependent DFT calculations for the fluoride anion sensor, 5,7-dibromo-8-tert-butyldimethylsilyloxy-2-methylquinoline (DBM), suggested a different sensing mechanism from the experimentally proposed one (Chem. Commun., 2011, 47, 7098). Instead of the formation of fluoridehydrogen-bond complex (DBMOHF) and excited-state proton transfer mechanism, the theoretical results predicted a sensing mechanism based on desilylation reaction and intramolecular charge transfer (ICT). The fluoride anion reacted with DBM and formed an anion (DBMO), with the ICT causing a red shift in the absorbance and emission spectra of the latter. The calculated vertical excitation energies in the ground and first excited states of both DBM and DBMO, as well as the calculated 1 H NMR spectra, significantly reproduced the experimental measurements, providing additional proofs for our proposed sensing mechanism for DBM.

Elaboration and controlling excited state double proton transfer mechanism of 2,5-bis(benzoxazol-2-yl)thiophene-3,4-diol

“…The relaxation of keto* results in the ground-state keto structure that undergoes a reverse ground state proton transfer back to enol species. It is the primary changes about electronic structures and charge distributions under the photoexcitation, ESPT processes own obviously different photophysical and photochemical properties providing various applications, such as chemical sensing11, fluorescence probes1213, while light LED14, cell imaging, and so forth151617.…”

First principle simulation on oxidation mechanism of diethyl ether by nitrogen dioxide

“…CCSD(T)), and may underestimate the reaction barrier, 11,12 DFT has been widely used in studying the molecular properties, the reaction mechanism such as oxidation reaction [13][14][15] and the binding energy because of the less computational intensity and moderate accuracy. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] In the present work, all of the electronic structure calculations were performed using the Gaussian 09 suite.…”

The investigation of excited state proton transfer mechanism in water-bridged 7-azaindole

“…Then, the investigation of the photo-induced proton transfer (PT) reaction involved in the inter-and intra-molecular hydrogen bond has attracted vast attentions based on both theoretical and experimental techniques . The strong and fast recombination of the charge distribution originated from the transferred tautomerization leads these molecules very fascinating towards the design and application of fluorescence chemosensors, laser dyes and LEDs, ultraviolet ray (UV) filters, molecular switches, and photostabilizers [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. In a word, due to the wide range of applications, more and more spectroscopic techniques have been employed to investigate PT reaction in recent years.…”

“…In order to clarify the mechanism of 7Al-2H 2 O ESIPT process in detail, density functional theory (DFT) and time dependent density functional theory (TDDFT) methods can be adopted to elaborate basic aspects involving in different electronic excited states and corresponding structures nowadays [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50].…”