Excited-state intramolecular proton transfer of 2-acetylindan-1,3-dione studied by ultrafast absorption and fluorescence spectroscopy

Abstract

We employ transient absorption from the deep-UV to the visible region and fluorescence upconversion to investigate the photoinduced excited-state intramolecular proton-transfer dynamics in a biologically relevant drug molecule, 2-acetylindan-1,3-dione. The molecule is a ß-diketone which in the electronic ground state exists as exocyclic enol with an intramolecular H-bond. Upon electronic excitation at 300 nm, the first excited state of the exocyclic enol is initially populated, followed by ultrafast proton transfer (≈160 fs) to form the vibrationally hot endocyclic enol. Subsequently, solvent-induced vibrational relaxation takes place (≈10 ps) followed by decay (≈390 ps) to the corresponding ground state.

Exploring the Ultrafast Excited-State Intramolecular Proton Transfer (ESIPT) of β-Diketones in the deep-UV

“…Yet, in all cases the same relaxation model could be applied. Recently, we could apply this scheme also to 2-acetylindan-1,3-dione, a biologically relevant β-diketone [7].…”

GPU‐Accelerated Large‐Scale Excited‐State Simulation Based on Divide‐and‐Conquer Time‐Dependent Density‐Functional Tight‐Binding

“…As a potential bio‐active drug molecule, AID was studied by various experimental and theoretical methods. Steady‐state measurements of AID reveal that the fluorescence spectrum does not demonstrate a mirror image and is largely red‐shifted compared with its absorption spectrum. It suggests that the intramolecular proton transfer occurs from AID‐enol to AID‐keto in the excited state, as shown in Figure .…”

“…It suggests that the intramolecular proton transfer occurs from AID‐enol to AID‐keto in the excited state, as shown in Figure . The experimental study reported that the time‐scale of the intramolecular proton transfer in the excited state was estimated to be ~160 fs.…”

“…Finally, the time‐course changes of the excitation energies are shown in Figure c. The dotted lines indicate the experimental values corresponding to absorption and fluorescence. At the intramolecular proton transfer, ~300 fs, excitation energy changed greatly.…”

Preface to Special Topic: Invited Papers of the 3rd International Conference on Ultrafast Structural Dynamics

“…Here, developments in the brightness and tunability of femtosecond pulsed high energy photons have also pushed the frontier for progress in developing such applications. 12 More generally, time-resolved linear spectroscopy is widely applicable to a variety of systems, ranging from chemicals in a solution 13,14 to warm dense matter. 15 …”