The revelation of ESIPT behavior and fluoride response mechanism for (E)‐2‐(((1H‐benzo[d]imidazol‐2‐yl)‐imino)methyl)‐5‐(dimethylamino)‐phenol

Abstract

Given the tremendous potential of fluorescence sensors in recent years, in this work, as a kind of novel and few studied sensor containing both NH and OH binding sites, (E)-2- (((1H-benzo[d]imidazol-2-yl)-imino)methyl)-5-(dimethylamino)-phenol (bip) has been investigated on the excited state intramolecular proton transfer (ESIPT) based on time-dependent density functional theory (TDDFT) method. Our simulated absorption and fluorescence spectra based on the TDDFT method are in agreement with the experimental results.Two kinds of bip structures could found in the S 1 state, which could be attributed to the ESIPT reaction. Hydrogen bond strengthening has been testified in the S 1 state based on comparing staple bond lengths and bond angles involved in hydrogen bond between S 0 and S 1 states. The calculated infrared (IR) vibrational spectra at the O-H stretching vibrational region and theoretical hydrogen bonding energy also declare the phenomenon of hydrogen bond strengthening. The frontier molecular orbitals (MOs) analysis and Natural bond orbital (NBO) manifest the intramolecular charge transfer (ICT) characteristic for bip chromophore, which reveals the tendency of proton transfer.The potential energy curvess of the S 0 and S 1 states are constructed to explain the mechanism of the proton transfer in excited state in detail. Further, given fluorescence sensing mechanism, we present the addition of fluoride anion can spontaneously capture the hydrogen proton of hydroxyl forming intermolecular hydrogen bond O-H···F, which results in the formation of anion product with response fluoride anion.

The influence of amino substituents on the signal‐output, selectivity, and sensitivity of a hydroxyaromatic 1,2,3‐triazolyl chemosensor for anions—A structure–property relationship investigation

“…For small molecule chemosensors, the mechanism of anion detection often involves hydrogen bonding with NH, [1][2][3][4] OH, [4][5][6][7] and sp 2 CH [8] groups. These interactions give rise to distinct emission color changes via processes such as excited state proton transfer (ESPT), [4,7] photoinduced electron transfer (PET), [3] excimer/exciplex formation, [1] and intramolecular charge transfer (ICT). [2,9] Chemosensors for fluoride (F − ) can be beneficial in different areas.…”

Sensing of fluoride anion based on desilylation and intramolecular charge transfer of 2‐[2‐(tert‐butyl‐diphenyl‐silanyloxy)‐phenyl]‐4,5‐diphenyl‐1H‐imidazole

“…[ 1–6 ] Particularly, the fluoride anion chemosensors have been focused on by researchers due to the considerable fundamental and significant roles of fluoride to environment, health and industrial behaviors, and so on. [ 7–18 ] It is well known that fluoride anion should be useful for human health, which could prevent and cure dental care and osteoporosis to some extent. One thing should be noticed that fluoride anion possesses its unique chemical and physical characteristics.…”

Spectroscopic and mechanistic insights into solvent mediated excited-state proton transfer and aggregation-induced emission: introduction of methyl group onto 2-(o-hydroxyphenyl)benzoxazole

“…Previously, highly reactive and non-emissive chargeseparated species exhibited aggregated-induced emission (AIE) in specific environments. [47][48][49][50][51] Therefore, the prohibited TICT structure was usually used to explain the mechanism of AIE enhancement. Excited-state photophysical and photochemical processes were simulated at the TD-B3LYP-D3/6-311+G(d,p) level of theory to explain the AIE enhancement of HBO-pCH 3 .…”