Time‐dependent density functional theory study on the electronic excited‐state hydrogen‐bonding dynamics of 4‐aminophthalimide (4AP) in aqueous solution: 4AP and 4AP–(H₂O)_1,2 clusters

Abstract

The time-dependent density functional theory (TDDFT) method has been carried out to investigate the excited-state hydrogen-bonding dynamics of 4-aminophthalimide (4AP) in hydrogen-donating water solvent. The infrared spectra of the hydrogen-bonded solute-solvent complexes in electronically excited state have been calculated using the TDDFT method. We have demonstrated that the intermolecular hydrogen bond C= O...H-O and N-H...O-H in the hydrogen-bonded 4AP-(H(2)O)(2) trimer are significantly strengthened in the electronically excited state by theoretically monitoring the changes of the bond lengths of hydrogen bonds and hydrogen-bonding groups in different electronic states. The hydrogen bonds strengthening in the electronically excited state are confirmed because the calculated stretching vibrational modes of the hydrogen bonding C=O, amino N-H, and H-O groups are markedly red-shifted upon photoexcitation. The calculated results are consistent with the mechanism of the hydrogen bond strengthening in the electronically excited state, while contrast with mechanism of hydrogen bond cleavage. Furthermore, we believe that the transient hydrogen bond strengthening behavior in electroniclly excited state of chromophores in hydrogen-donating solvents exists in many other systems in solution.

Analytical nuclear excited‐state gradients for the Tamm–Dancoff approximation using uncoupled frozen‐density embedding

“…4‐aminophthalimide (4AP) has been used for a range of applications since the fluorescence energies and lifetimes are sensitive to the environment, see Ref. [ ] and references therein. Wang et al have reported a 4AP–(H 2 O) 2 cluster, see Figure , which exhibits a solvatochromic red shift of about −0.29 eV in vertical excitation energies (VEEs) and −0.35 eV in vertical fluorescence energies for the S state in TDDFT calculations .…”

Investigating the molecular and aggregated states of a drug molecule rutaecarpine using spectroscopy, microscopy, crystallography and computational studies

“…Excited state calculations were done using the time-dependent DFT (TD-DFT) 54 formalism. 57,58 3. All the calculations were performed by using Gaussian09 programming package.…”

Hydrogen-bonding dynamics of photoexcited coumarin 138 and 339 in protic methanol solution: Time-dependent density functional theory study

“…The theoretical calculations are useful to describe the early time hydrogen bond response to the electronic excitation and explain the mechanism of photophysical processes. In the past years, the time-dependent density functional theory (TDDFT) method is extensively employed to investigate the excited-state dynamics, which have been demonstrated a reliable tool to study the ultrafast photophysical phenomenon [20,[28][29][30][31][32][33].…”