Ultrafast Excited State Relaxation Dynamics of New Fuchsine‐ a Triphenylmethane Derivative Dye

Abstract

An all-inclusive investigation of the ultrafast excited state relaxation dynamics of a triphenylmethane derivative molecule, New Fuchsine (NF), using a combined approach of density functional theory (DFT), femtosecond transient absorption spectroscopy (fs-TAS), and photoluminescence spectroscopy is presented in this work. The DFT calculations confirmed the formation of twisted molecular structure in the excited state of NF in ethanol solution with bond rotation of � 86°. TAS measurements of NF solution exhibited ultrafast ground staterecovery pathway via a conical intersection confirming an ultrafast structural reorientation. On the contrary, TAS measurements of NF thin-film exhibited a longer excited-state lifetime suggesting a hindered molecular twisted state formed as an intermediate step. Photophysical kinetic models are proposed to globally fit the fs-TAS data establishing the twisted intramolecular charge transfer (TICT) state mediated ground state recovery for NF in solution and thin film, respectively. Temperature-dependent photoluminescence study of NF film provided a clear insight into the effect of rotational motion of phenyl rings in NF molecules over the TICT mediated emission.

Theoretical insights into the impact of hydrogen bonding interactions and proton‐transfer phenomena on the excited state of HBT‐TMS fluorophore: Solvent‐induced effects

“…Typically, this phenomenon is observed in fluorophores that exhibit a suitable conformation featuring both a protic acid group and a basic site [8][9][10]. The successful ESIPT reactions can lead to an increase in the related basicity and acidity of these moieties upon photoexcitation, thereby enabling a wide range of potential applications including laser dyes, UV-light polymer stabilizers, fluorescent sensors, molecular switches, and organic light emitting diodes, among others [11][12][13][14][15][16][17][18][19][20].…”