Photo-induced proton transfer in fluorene- and carbazole-based compounds as red- and orange-light-emitting molecules: A TD-DFT study

Tuning the photophysical properties of ESIPT active unsymmetrical azine dyes by the change in the substituent and solvent: TD-PBE0 and TD-CAM-B3LYP studies

“…56 To further investigate the ESIPT process, the potential energy curves (PECs) along the proton transfer path were constructed by freezing the O-H coordinate to a series of values and then optimizing the rest of the coordinates using the PBE0 method at the S 0 state and the TD-PBE0 method at the S 1 state. 42,57,58 To characterize the hydrogen bonds with different strengths, the quantum theory of atoms in molecules (QTAIM) analysis 59,60 was performed at the Fig. 1 The PBE0 optimized structures of L1-L5 at S 0 and S 1 states (the key bond lengths in Å are also shown).…”

“…56 To further investigate the ESIPT process, the potential energy curves (PECs) along the proton transfer path were constructed by freezing the O–H coordinate to a series of values and then optimizing the rest of the coordinates using the PBE0 method at the S 0 state and the TD-PBE0 method at the S 1 state. 42,57,58 To characterize the hydrogen bonds with different strengths, the quantum theory of atoms in molecules (QTAIM) analysis 59,60 was performed at the PBE0/6-31++G(d,p) level of theory by using the AIM2000 program package. 61 Besides, for revealing the intramolecular hydrogen bonding interactions in real space and to compare the hydrogen bond strength, the reduced density gradient (RDG) isosurfaces 62 were calculated using Multiwfn software 63 and plotted using the (VMD) program.…”

TD-DFT study of the excited state intramolecular proton transfer (ESIPT) mechanism and photophysical properties in coumarin–benzothiazole derivatives: substitution and solvent effects

“…74 The electronic excited state S 1 was optimized at the TD-DFT/6-311++G(d,p) level of theory. [75][76][77][78] The potential energy curves (PECs) related to the proton transfer of studied molecules at the S 0 and S 1 states were calculated to investigate the proton transfer barriers and understand the ESIPT mechanism. For the construction of PE curves, all degrees of freedom are relaxed without any symmetry constraints during the proton transfer, except for the reaction coordinate (O-H bond length).…”

Modulating excited‐state intramolecular proton transfer of 2‐(5‐(4‐carboxyphenyl)‐2‐hydroxyphenyl)benzothiazole depending on substituents: A DFT/TD‐DFT study

“…The proton driven by the intramolecular H‐bond can exchange from the acid group (e.g., NH 2 , OH, and SH) to the basic site (e.g., O, N, and S) via forming a five‐, six‐, or seven‐membered ring. [ 27–34 ] Compared with the amino‐type ESIPT systems, [ 35–42 ] numerous studies on OH‐type H‐bonding molecules are much more reported. [ 17,43–56 ] This is mainly because the H‐bond in the OH‐type system is stronger than that in the NH‐type, which leads to a smaller or no barrier of ESIPT in OH‐type molecules.…”