Theoretical Study on the Sensing Mechanism of Novel Hydrazine Sensor TAPHP and Its ESIPT and ICT Processes

Abstract

The photophysical and photochemical properties of the novel hydrazine sensor TAPHP and the TAPDP generated by the cyclization reaction of TAPHP with hydrazine are investigated using the density functional theory and time-dependent density functional theory. The results show that both the excited-state intramolecular proton transfer and intramolecular charge transfer can occur for TAPHP and TAPDP. Analysis of bond parameters and infrared vibrational spectra indicate that hydrogen bonds are enhanced in the first excited state, which is beneficial to excited-state intramolecular proton transfer. The strength of hydrogen bonds is also visualized by using the independent gradient model and topological analysis. The core-valence bifurcation index and bond critical point parameters are further employed to measure hydrogen bonds. The reaction path of proton transfer is obtained through the potential energy curves. The excitation of TAPHP and TAPDP is attributed to the charge transfer excitation, which is determined by the characteristics of the hole-electron distribution. The reaction site and product configuration are verified by atomic charge and 1 H-NMR spectra. The negative free energy difference indicates that the reaction between TAPHP and hydrazine can proceed spontaneously. In addition, the absorption and fluorescence spectra agree well with the experimental results, confirming that TAPHP is an excellent sensor of hydrazine.

Fluoride anion sensing mechanism of 2‐(quinolin‐2‐yl)‐3‐hydroxy‐4H‐chromen‐4‐one chemosensor based on inhibition of excited state intramolecular ultrafast proton transfer

“…As far as we know, even though the TDDFT/B3LYP theoretical level might not become accurately sufficient to surmount the accurate ordering of the closely spaced excited states, previous theoretical works have revealed the reliability as far as the shape of ESIPT potential energy curves is concerned. [ 71–84 ] That is to say, the theoretical constructed potential energy curves could provide reasonable explanations about excited state dynamical processes. Thus, in this work, we adopt this manner to explore the ESIPT reaction and mechanism for Qu3HC system.…”

“…Similar with discussing the ESIPT mechanism of Qu3HC itself above, the investigation about potential energy curve should be a good manner to explore protonated and deprotonated reactions in both ground and excited states. [ 71–84 ] In fact, it could be clearly seen that the potential energy curve decreases along with the shortening of H and F atoms until the length of H–F reaches 1.0 Å. That is to say, the fluoride‐triggered deprotonation reaction happens spontaneously forming the Qu3HC‐A structure in the ground state.…”

π‐Extended Push‐Pull‐Type Bicyclic Fluorophores Based on Quinoline and Naphthyridine Frameworks with an Iminophosphorane Fragment

“…This indicates that charge separation might correspond mainly between the HOMO!LUMO transition in both derivatives. To evaluate the relationship between the amplitude of charge separation and the molecular structures, using the Multiwfn program, [29] S r and t indices [29,30] were calculated: 0.645 a.u. and À 0.325 Å for 1 and 0.682 a.u.…”

Accurate Analysis of Anisotropic Carrier Mobility and Structure–property Relationships in Organic BOXD Crystalline Materials

“…However, even for the simplest single crystalline materials, it is difficult to find a precise connection between the crystal structures and their micromechanisms such as anisotropic practical transport, structural deformation, and mechanical properties of anisotropy ( Zhang et al, 2016 ; Ji et al, 2017 ; and Lin et al, 2020 ). There are enormous applications of organic crystals, such as OFET and OLET ( Wise et al, 2018 ; Liu S. et al, 2020 ; Bi et al, 2021 ; and Wang et al, 2021 ). In particular, their requirements for crystal quality and high mobility have prompted the development of more crystal materials ( Cho et al, 2020 ; Sharma et al, 2020 ; and Chen et al, 2021 ).…”