.png){kind=icon}
.png){kind=icon}
Return
Role of hydroxy substitution on the conformation and excited state dynamics of chalcone
.png){kind=icon}
PRE
AI
S
B
N
DOI：10.1039/D6CP00585C.png)
.png){kind=icon}
Original request for help.png){kind=icon}
Share.png){kind=icon}
Save
Abstract
En 中文
Chalcones; a class of α; β-unsaturated carbonyl compounds with rich photophysical properties; were investigated together with an ortho-hydroxy-substituted analogue (2-hydroxychalcone) using a combination of steady-state and ultrafast spectroscopy supported by quantum chemical calculations. Steady-state absorption measurements reveal that 2-hydroxychalcone exists as an equilibrium mixture of ground-state conformers in solution; giving rise to two distinct absorption bands with pronounced solvent dependence. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations provide a conformer-resolved interpretation of the electronic spectra and indicate enhanced charge-transfer character for the lower-energy absorbing conformer in polar solvents. Femtosecond transient absorption spectroscopy uncovers a striking contrast in the excited-state relaxation pathways of unsubstituted chalcone and 2-hydroxychalcone. Photoexcitation of the unsubstituted chalcone to the ππ* (S2) state leads to the formation of a transient absorption band centered near 460 nm; which decays on a picosecond timescale to yield the triplet state. In contrast; excitation of 2-hydroxychalcone to the ππ* state reveals two distinct transient species: a short-lived absorption band centered around 600 nm; assigned to the nπ* (S1) singlet state; and a longer-lived transient near 490 nm; attributed to a twisted S1 singlet state formed within approximately 2 ps of optical excitation. The excited-state relaxation of 2-hydroxychalcone is dominated by barrierless dihedral twisting; which drives structural reorganization within the singlet manifold. The observation of coherent low-frequency vibrational wavepacket motion provides direct spectroscopic evidence for this torsion-driven relaxation pathway. These results highlight how ortho-hydroxy substitution fundamentally alters excited-state dynamics by suppressing triplet formation and promoting structurally driven; coherent relaxation; offering new insights into the photophysics of chalcone-based systems.
Journal
P
IF:
0
Papers:
964
Citations:
0
Organization
Cited Papers