Fluorescence and solvent-dependent phosphorescence studies of o-nitrobenzaldehyde: A combined experimental and theoretical investigation

Abstract

The fluorescence and phosphorescence emission studies have been performed to understand the photochemistry of o-nitrobenzaldehyde in solution upon photoexcitation to the first excited singlet state (S(1)). The presence of an energy barrier in the S(1)-state hydrogen transfer potential energy surface is determined experimentally through the observed dual fluorescence emission, and the barrier height is estimated to be about 84-87 kcal mol(-1) by gradually decreasing the excitation energy. The phosphorescence spectra of o-NBA in five different solvents are observed for the first time, providing direct experimental evidence on the existence of triplet manifold in the photoexcitation of o-NBA. Furthermore, the relative phosphorescence quantum yield is found to be solvent dependent. To get further insights into the dynamic process involved in the photochemistry of o-NBA, excited state calculations at the TD-B3LYP/6-311+G(d,p) level of theory with the PCM model are accomplished, which strongly support our experimental findings.

UV-irradiation of self-assembled triphenylamines affords persistent and regenerable radicals

“…3B and C). Solvent dependent phosphorescence has been observed before when S 1 and T n were similar in energy 33. In this situation, different solvents stabilized either state in varying degrees resulting in different phosphorescent quantum yields for each solvent, which may be the case here as well.…”

A non-adiabatic quantum-classical dynamics study of the intramolecular excited state hydrogen transfer in ortho-nitrobenzaldehyde

“…The passage through the (S 1 /S 0 ) X-HT crossing explains the formation of the product in the ground state on the femtosecond scale, in agreement with the experiment. In contrast to this, recent DFT based calculations by Cheng et al 49 propose that the hydrogen transfer takes place only on the S 1 surface and leads to the excited-state ketene. The latter mechanism was obtained by optimizing the hydrogen transfer coordinate in the ground state and calculating the excited-state energy profile with single point calculations on the ground state structures.…”

Different mechanisms of ultrafast excited state deactivation of coumarin 500 in dioxane and methanol solvents: experimental and theoretical study

“…Vertical singletstate excitation energy calculations and excited state geometry optimizations were performed using the time-dependent density functional (TDDFT) method and the same exchange correlation potential that was used for the ground state calculations. [50][51][52][53][54][55][56][57][58][59][60][61] The resolution of the identity (RI) approximation was also used to improve the efficiency without sacricing the accuracy of the results. [51][52][53] Previous electronic structure computations were performed with the Turbomole program suite.…”